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ARROW-14917: [C++] Implement GcsFileSystem::CreateDir#11842

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ARROW-14917: [C++] Implement GcsFileSystem::CreateDir #11842

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ARROW-14917: [C++] GcsFileSystem can create directories
coryan Dec 2, 2021
e74fb5b
Address review comments
coryan Dec 7, 2021
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94 changes: 79 additions & 15 deletions cpp/src/arrow/filesystem/gcsfs.cc
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Open in desktop
Original file line numberDiff line numberDiff line change
Expand Up@@ -34,7 +34,6 @@ namespace {

namespace gcs = google::cloud::storage;

auto constexpr kSep = '/';
// Change the default upload buffer size. In general, sending larger buffers is more
// efficient with GCS, as each buffer requires a roundtrip to the service. With formatted
// output (when using `operator<<`), keeping a larger buffer in memory before uploading
Expand All@@ -49,18 +48,17 @@ struct GcsPath {
std::string object;

static Result<GcsPath> FromString(const std::string& s) {
const auto src = internal::RemoveTrailingSlash(s);
auto const first_sep = src.find_first_of(kSep);
auto const first_sep = s.find_first_of(internal::kSep);
if (first_sep == 0) {
return Status::Invalid("Path cannot start with a separator ('", s, "')");
}
if (first_sep == std::string::npos) {
return GcsPath{std::string(src), std::string(src), ""};
return GcsPath{s, internal::RemoveTrailingSlash(s).to_string(), ""};
}
GcsPath path;
path.full_path = std::string(src);
path.bucket = std::string(src.substr(0, first_sep));
path.object = std::string(src.substr(first_sep + 1));
path.full_path = s;
path.bucket = s.substr(0, first_sep);
path.object = s.substr(first_sep + 1);
return path;
}

Expand DownExpand Up@@ -275,12 +273,73 @@ class GcsFileSystem::Impl {
const GcsOptions& options() const { return options_; }

Result<FileInfo> GetFileInfo(const GcsPath& path) {
if (!path.object.empty()) {
auto meta = client_.GetObjectMetadata(path.bucket, path.object);
return GetFileInfoImpl(path, std::move(meta).status(), FileType::File);
if (path.object.empty()) {
auto meta = client_.GetBucketMetadata(path.bucket);
return GetFileInfoImpl(path, std::move(meta).status(), FileType::Directory);
}
auto meta = client_.GetBucketMetadata(path.bucket);
return GetFileInfoImpl(path, std::move(meta).status(), FileType::Directory);
auto meta = client_.GetObjectMetadata(path.bucket, path.object);
return GetFileInfoImpl(
path, std::move(meta).status(),
path.object.back() == '/' ? FileType::Directory : FileType::File);
}

// GCS does not have directories or folders. But folders can be emulated (with some
// limitations) using marker objects. That and listing with prefixes creates the
// illusion of folders.
google::cloud::Status CreateDirMarker(const std::string& bucket,
util::string_view name) {
// Make the name canonical.
const auto canonical = internal::EnsureTrailingSlash(name);
return client_
.InsertObject(bucket, canonical, std::string(),
gcs::WithObjectMetadata(gcs::ObjectMetadata().upsert_metadata(
"arrow/gcsfs", "directory")))
.status();
}

google::cloud::Status CreateDirMarkerRecursive(const std::string& bucket,
const std::string& object) {
using GcsCode = google::cloud::StatusCode;
auto get_parent = [](std::string const& path) {
return std::move(internal::GetAbstractPathParent(path).first);
};
// Maybe counterintuitively we create the markers from the most nested and up. Because
// GCS does not have directories creating `a/b/c` will succeed, even if `a/` or `a/b/`
// does not exist. In the common case, where `a/b/` may already exist, it is more
// efficient to just create `a/b/c/` and then find out that `a/b/` was already there.
// In the case where none exists, it does not matter which order we follow.
auto status = CreateDirMarker(bucket, object);
if (status.code() == GcsCode::kAlreadyExists) return {};
if (status.code() == GcsCode::kNotFound) {
// Missing bucket, create it first ...
status = client_.CreateBucket(bucket, gcs::BucketMetadata()).status();
if (status.code() != GcsCode::kOk && status.code() != GcsCode::kAlreadyExists) {
return status;
}
}

for (auto parent = get_parent(object); !parent.empty(); parent = get_parent(parent)) {
status = CreateDirMarker(bucket, parent);
if (status.code() == GcsCode::kAlreadyExists) {
break;
}
if (!status.ok()) {
return status;
}
}
return {};
}

Status CreateDir(const GcsPath& p) {
if (p.object.empty()) {
return internal::ToArrowStatus(
client_.CreateBucket(p.bucket, gcs::BucketMetadata()).status());
}
return internal::ToArrowStatus(CreateDirMarker(p.bucket, p.object));
}

Status CreateDirRecursive(const GcsPath& p) {
return internal::ToArrowStatus(CreateDirMarkerRecursive(p.bucket, p.object));
}

Status DeleteFile(const GcsPath& p) {
Expand DownExpand Up@@ -332,12 +391,15 @@ class GcsFileSystem::Impl {
static Result<FileInfo> GetFileInfoImpl(const GcsPath& path,
const google::cloud::Status& status,
FileType type) {
const auto& canonical = type == FileType::Directory
? internal::EnsureTrailingSlash(path.full_path)
: path.full_path;
Comment thread
pitrou marked this conversation as resolved.
if (status.ok()) {
return FileInfo(path.full_path, type);
return FileInfo(canonical, type);
}
using ::google::cloud::StatusCode;
if (status.code() == StatusCode::kNotFound) {
return FileInfo(path.full_path, FileType::NotFound);
return FileInfo(canonical, FileType::NotFound);
}
return internal::ToArrowStatus(status);
}
Expand DownExpand Up@@ -373,7 +435,9 @@ Result<FileInfoVector> GcsFileSystem::GetFileInfo(const FileSelector& select) {
}

Status GcsFileSystem::CreateDir(const std::string& path, bool recursive) {
return Status::NotImplemented("The GCS FileSystem is not fully implemented");
ARROW_ASSIGN_OR_RAISE(auto p, GcsPath::FromString(path));
if (!recursive) return impl_->CreateDir(p);
return impl_->CreateDirRecursive(p);
}

Status GcsFileSystem::DeleteDir(const std::string& path) {
Expand Down
52 changes: 36 additions & 16 deletions cpp/src/arrow/filesystem/gcsfs.h
View file
Open in desktop
Original file line numberDiff line numberDiff line change
Expand Up@@ -40,24 +40,43 @@ struct ARROW_EXPORT GcsOptions {
bool Equals(const GcsOptions& other) const;
};

// - TODO(ARROW-1231) - review this documentation before closing the bug.
/// \brief GCS-backed FileSystem implementation.
///
/// Some implementation notes:
/// - TODO(ARROW-1231) - review all the notes once completed.
/// - buckets are treated as top-level directories on a "root".
/// - GCS buckets are in a global namespace, only one bucket
/// named `foo` exists in Google Cloud.
/// - Creating new top-level directories is implemented by creating
/// a bucket, this may be a slower operation than usual.
/// - A principal (service account, user, etc) can only list the
/// buckets for a single project, but can access the buckets
/// for many projects. It is possible that listing "all"
/// the buckets returns fewer buckets than you have access to.
/// - GCS does not have directories, they are emulated in this
/// library by listing objects with a common prefix.
/// - In general, GCS has much higher latency than local filesystems.
/// The throughput of GCS is comparable to the throughput of
/// a local file system.
/// GCS (Google Cloud Storage - https://cloud.google.com/storage) is a scalable object
/// storage system for any amount of data. The main abstractions in GCS are buckets and
/// objects. A bucket is a namespace for objects, buckets can store any number of objects,
/// tens of millions and even billions is not uncommon. Each object contains a single
/// blob of data, up to 5TiB in size. Buckets are typically configured to keep a single
/// version of each object, but versioning can be enabled. Versioning is important because
/// objects are immutable, once created one cannot append data to the object or modify the
/// object data in any way.
///
/// GCS buckets are in a global namespace, if a Google Cloud customer creates a bucket
/// named `foo` no other customer can create a bucket with the same name. Note that a
/// principal (a user or service account) may only list the buckets they are entitled to,
/// and then only within a project. It is not possible to list "all" the buckets.
///
/// Within each bucket objects are in flat namespace. GCS does not have folders or
/// directories. However, following some conventions it is possible to emulate
/// directories. To this end, this class:
///
/// - All buckets are treated as directories at the "root"
/// - Creating a root directory results in a new bucket being created, this may be slower
/// than most GCS operations.
/// - Any object with a name ending with a slash (`/`) character is treated as a
/// directory.
/// - The class creates marker objects for a directory, using a trailing slash in the
/// marker names. For debugging purposes, the metadata of these marker objects indicate
/// that they are markers created by this class. The class does not rely on this
/// annotation.
/// - GCS can list all the objects with a given prefix, this is used to emulate listing
/// of directories.
/// - In object lists GCS can summarize all the objects with a common prefix as a single
/// entry, this is used to emulate non-recursive lists. Note that GCS list time is
/// proportional to the number of objects in the prefix. Listing recursively takes
/// almost the same time as non-recursive lists.
///
class ARROW_EXPORT GcsFileSystem : public FileSystem {
public:
~GcsFileSystem() override = default;
Expand All@@ -75,6 +94,7 @@ class ARROW_EXPORT GcsFileSystem : public FileSystem {

Status DeleteDirContents(const std::string& path) override;

/// This is not implemented in GcsFileSystem, as it would be too dangerous.
Status DeleteRootDirContents() override;

Status DeleteFile(const std::string& path) override;
Expand Down
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ARROW-14917: [C++] Implement GcsFileSystem::CreateDir by coryan · Pull Request #11842 · apache/arrow · GitHub
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ARROW-14917: [C++] Implement GcsFileSystem::CreateDir#11842

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ARROW-14917: [C++] Implement GcsFileSystem::CreateDir
#11842
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ARROW-14917: [C++] GcsFileSystem can create directories


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e74fb5b

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coryan Dec 7, 2021

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94 changes: 79 additions & 15 deletions
cpp/src/arrow/filesystem/gcsfs.cc

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -34,7 +34,6 @@ namespace {

namespace gcs = google::cloud::storage;

auto constexpr kSep = '/';
// Change the default upload buffer size. In general, sending larger buffers is more
// efficient with GCS, as each buffer requires a roundtrip to the service. With formatted
// output (when using `operator<<`), keeping a larger buffer in memory before uploading
Expand All@@ -49,18 +48,17 @@ struct GcsPath {
 std::string object;

 static Result<GcsPath> FromString(const std::string& s) {
 const auto src = internal::RemoveTrailingSlash(s);
 auto const first_sep = src.find_first_of(kSep);
 auto const first_sep = s.find_first_of(internal::kSep);
 if (first_sep == 0) {
 return Status::Invalid("Path cannot start with a separator ('", s, "')");
 }
 if (first_sep == std::string::npos) {
 return GcsPath{std::string(src), std::string(src), ""};
 return GcsPath{s, internal::RemoveTrailingSlash(s).to_string(), ""};
 }
 GcsPath path;
 path.full_path = std::string(src);
 path.bucket = std::string(src.substr(0, first_sep));
 path.object = std::string(src.substr(first_sep + 1));
 path.full_path = s;
 path.bucket = s.substr(0, first_sep);
 path.object = s.substr(first_sep + 1);
 return path;
 }

Expand DownExpand Up@@ -275,12 +273,73 @@ class GcsFileSystem::Impl {
 const GcsOptions& options() const { return options_; }

 Result<FileInfo> GetFileInfo(const GcsPath& path) {
 if (!path.object.empty()) {
 auto meta = client_.GetObjectMetadata(path.bucket, path.object);
 return GetFileInfoImpl(path, std::move(meta).status(), FileType::File);
 if (path.object.empty()) {
 auto meta = client_.GetBucketMetadata(path.bucket);
 return GetFileInfoImpl(path, std::move(meta).status(), FileType::Directory);
 }
 auto meta = client_.GetBucketMetadata(path.bucket);
 return GetFileInfoImpl(path, std::move(meta).status(), FileType::Directory);
 auto meta = client_.GetObjectMetadata(path.bucket, path.object);
 return GetFileInfoImpl(
 path, std::move(meta).status(),
 path.object.back() == '/' ? FileType::Directory : FileType::File);
 }

 // GCS does not have directories or folders. But folders can be emulated (with some
 // limitations) using marker objects. That and listing with prefixes creates the
 // illusion of folders.
 google::cloud::Status CreateDirMarker(const std::string& bucket,
 util::string_view name) {
 // Make the name canonical.
 const auto canonical = internal::EnsureTrailingSlash(name);
 return client_
 .InsertObject(bucket, canonical, std::string(),
 gcs::WithObjectMetadata(gcs::ObjectMetadata().upsert_metadata(
 "arrow/gcsfs", "directory")))
 .status();
 }

 google::cloud::Status CreateDirMarkerRecursive(const std::string& bucket,
 const std::string& object) {
 using GcsCode = google::cloud::StatusCode;
 auto get_parent = [](std::string const& path) {
 return std::move(internal::GetAbstractPathParent(path).first);
 };
 // Maybe counterintuitively we create the markers from the most nested and up. Because
 // GCS does not have directories creating `a/b/c` will succeed, even if `a/` or `a/b/`
 // does not exist. In the common case, where `a/b/` may already exist, it is more
 // efficient to just create `a/b/c/` and then find out that `a/b/` was already there.
 // In the case where none exists, it does not matter which order we follow.
 auto status = CreateDirMarker(bucket, object);
 if (status.code() == GcsCode::kAlreadyExists) return {};
 if (status.code() == GcsCode::kNotFound) {
 // Missing bucket, create it first ...
 status = client_.CreateBucket(bucket, gcs::BucketMetadata()).status();
 if (status.code() != GcsCode::kOk && status.code() != GcsCode::kAlreadyExists) {
 return status;
 }
 }

 for (auto parent = get_parent(object); !parent.empty(); parent = get_parent(parent)) {
 status = CreateDirMarker(bucket, parent);
 if (status.code() == GcsCode::kAlreadyExists) {
 break;
 }
 if (!status.ok()) {
 return status;
 }
 }
 return {};
 }

 Status CreateDir(const GcsPath& p) {
 if (p.object.empty()) {
 return internal::ToArrowStatus(
 client_.CreateBucket(p.bucket, gcs::BucketMetadata()).status());
 }
 return internal::ToArrowStatus(CreateDirMarker(p.bucket, p.object));
 }

 Status CreateDirRecursive(const GcsPath& p) {
 return internal::ToArrowStatus(CreateDirMarkerRecursive(p.bucket, p.object));
 }

 Status DeleteFile(const GcsPath& p) {
Expand DownExpand Up@@ -332,12 +391,15 @@ class GcsFileSystem::Impl {
 static Result<FileInfo> GetFileInfoImpl(const GcsPath& path,
 const google::cloud::Status& status,
 FileType type) {
 const auto& canonical = type == FileType::Directory
 ? internal::EnsureTrailingSlash(path.full_path)
 : path.full_path;
Comment thread
pitrou marked this conversation as resolved.

 if (status.ok()) {
 return FileInfo(path.full_path, type);
 return FileInfo(canonical, type);
 }
 using ::google::cloud::StatusCode;
 if (status.code() == StatusCode::kNotFound) {
 return FileInfo(path.full_path, FileType::NotFound);
 return FileInfo(canonical, FileType::NotFound);
 }
 return internal::ToArrowStatus(status);
 }
Expand DownExpand Up@@ -373,7 +435,9 @@ Result<FileInfoVector> GcsFileSystem::GetFileInfo(const FileSelector& select) {
}

Status GcsFileSystem::CreateDir(const std::string& path, bool recursive) {
 return Status::NotImplemented("The GCS FileSystem is not fully implemented");
 ARROW_ASSIGN_OR_RAISE(auto p, GcsPath::FromString(path));
 if (!recursive) return impl_->CreateDir(p);
 return impl_->CreateDirRecursive(p);
}

Status GcsFileSystem::DeleteDir(const std::string& path) {
Expand Down

52 changes: 36 additions & 16 deletions
cpp/src/arrow/filesystem/gcsfs.h

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -40,24 +40,43 @@ struct ARROW_EXPORT GcsOptions {
 bool Equals(const GcsOptions& other) const;
};

// - TODO(ARROW-1231) - review this documentation before closing the bug.
/// \brief GCS-backed FileSystem implementation.
///
/// Some implementation notes:
/// - TODO(ARROW-1231) - review all the notes once completed.
/// - buckets are treated as top-level directories on a "root".
/// - GCS buckets are in a global namespace, only one bucket
/// named `foo` exists in Google Cloud.
/// - Creating new top-level directories is implemented by creating
/// a bucket, this may be a slower operation than usual.
/// - A principal (service account, user, etc) can only list the
/// buckets for a single project, but can access the buckets
/// for many projects. It is possible that listing "all"
/// the buckets returns fewer buckets than you have access to.
/// - GCS does not have directories, they are emulated in this
/// library by listing objects with a common prefix.
/// - In general, GCS has much higher latency than local filesystems.
/// The throughput of GCS is comparable to the throughput of
/// a local file system.
/// GCS (Google Cloud Storage - https://cloud.google.com/storage) is a scalable object
/// storage system for any amount of data. The main abstractions in GCS are buckets and
/// objects. A bucket is a namespace for objects, buckets can store any number of objects,
/// tens of millions and even billions is not uncommon. Each object contains a single
/// blob of data, up to 5TiB in size. Buckets are typically configured to keep a single
/// version of each object, but versioning can be enabled. Versioning is important because
/// objects are immutable, once created one cannot append data to the object or modify the
/// object data in any way.
///
/// GCS buckets are in a global namespace, if a Google Cloud customer creates a bucket
/// named `foo` no other customer can create a bucket with the same name. Note that a
/// principal (a user or service account) may only list the buckets they are entitled to,
/// and then only within a project. It is not possible to list "all" the buckets.
///
/// Within each bucket objects are in flat namespace. GCS does not have folders or
/// directories. However, following some conventions it is possible to emulate
/// directories. To this end, this class:
///
/// - All buckets are treated as directories at the "root"
/// - Creating a root directory results in a new bucket being created, this may be slower
/// than most GCS operations.
/// - Any object with a name ending with a slash (`/`) character is treated as a
/// directory.
/// - The class creates marker objects for a directory, using a trailing slash in the
/// marker names. For debugging purposes, the metadata of these marker objects indicate
/// that they are markers created by this class. The class does not rely on this
/// annotation.
/// - GCS can list all the objects with a given prefix, this is used to emulate listing
/// of directories.
/// - In object lists GCS can summarize all the objects with a common prefix as a single
/// entry, this is used to emulate non-recursive lists. Note that GCS list time is
/// proportional to the number of objects in the prefix. Listing recursively takes
/// almost the same time as non-recursive lists.
///
class ARROW_EXPORT GcsFileSystem : public FileSystem {
 public:
 ~GcsFileSystem() override = default;
Expand All@@ -75,6 +94,7 @@ class ARROW_EXPORT GcsFileSystem : public FileSystem {

 Status DeleteDirContents(const std::string& path) override;

 /// This is not implemented in GcsFileSystem, as it would be too dangerous.
 Status DeleteRootDirContents() override;

 Status DeleteFile(const std::string& path) override;
Expand Down
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ARROW-14917: [C++] Implement GcsFileSystem::CreateDir by coryan · Pull Request #11842 · apache/arrow · GitHub
Skip to content
ARROW-14917: [C++] Implement GcsFileSystem::CreateDir#11842

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ARROW-14917: [C++] Implement GcsFileSystem::CreateDir
#11842
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df24c4b

ARROW-14917: [C++] GcsFileSystem can create directories


coryan Dec 2, 2021
e74fb5b

Address review comments


coryan Dec 7, 2021

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94 changes: 79 additions & 15 deletions
cpp/src/arrow/filesystem/gcsfs.cc

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -34,7 +34,6 @@ namespace {

namespace gcs = google::cloud::storage;

auto constexpr kSep = '/';
// Change the default upload buffer size. In general, sending larger buffers is more
// efficient with GCS, as each buffer requires a roundtrip to the service. With formatted
// output (when using `operator<<`), keeping a larger buffer in memory before uploading
Expand All@@ -49,18 +48,17 @@ struct GcsPath {
 std::string object;

 static Result<GcsPath> FromString(const std::string& s) {
 const auto src = internal::RemoveTrailingSlash(s);
 auto const first_sep = src.find_first_of(kSep);
 auto const first_sep = s.find_first_of(internal::kSep);
 if (first_sep == 0) {
 return Status::Invalid("Path cannot start with a separator ('", s, "')");
 }
 if (first_sep == std::string::npos) {
 return GcsPath{std::string(src), std::string(src), ""};
 return GcsPath{s, internal::RemoveTrailingSlash(s).to_string(), ""};
 }
 GcsPath path;
 path.full_path = std::string(src);
 path.bucket = std::string(src.substr(0, first_sep));
 path.object = std::string(src.substr(first_sep + 1));
 path.full_path = s;
 path.bucket = s.substr(0, first_sep);
 path.object = s.substr(first_sep + 1);
 return path;
 }

Expand DownExpand Up@@ -275,12 +273,73 @@ class GcsFileSystem::Impl {
 const GcsOptions& options() const { return options_; }

 Result<FileInfo> GetFileInfo(const GcsPath& path) {
 if (!path.object.empty()) {
 auto meta = client_.GetObjectMetadata(path.bucket, path.object);
 return GetFileInfoImpl(path, std::move(meta).status(), FileType::File);
 if (path.object.empty()) {
 auto meta = client_.GetBucketMetadata(path.bucket);
 return GetFileInfoImpl(path, std::move(meta).status(), FileType::Directory);
 }
 auto meta = client_.GetBucketMetadata(path.bucket);
 return GetFileInfoImpl(path, std::move(meta).status(), FileType::Directory);
 auto meta = client_.GetObjectMetadata(path.bucket, path.object);
 return GetFileInfoImpl(
 path, std::move(meta).status(),
 path.object.back() == '/' ? FileType::Directory : FileType::File);
 }

 // GCS does not have directories or folders. But folders can be emulated (with some
 // limitations) using marker objects. That and listing with prefixes creates the
 // illusion of folders.
 google::cloud::Status CreateDirMarker(const std::string& bucket,
 util::string_view name) {
 // Make the name canonical.
 const auto canonical = internal::EnsureTrailingSlash(name);
 return client_
 .InsertObject(bucket, canonical, std::string(),
 gcs::WithObjectMetadata(gcs::ObjectMetadata().upsert_metadata(
 "arrow/gcsfs", "directory")))
 .status();
 }

 google::cloud::Status CreateDirMarkerRecursive(const std::string& bucket,
 const std::string& object) {
 using GcsCode = google::cloud::StatusCode;
 auto get_parent = [](std::string const& path) {
 return std::move(internal::GetAbstractPathParent(path).first);
 };
 // Maybe counterintuitively we create the markers from the most nested and up. Because
 // GCS does not have directories creating `a/b/c` will succeed, even if `a/` or `a/b/`
 // does not exist. In the common case, where `a/b/` may already exist, it is more
 // efficient to just create `a/b/c/` and then find out that `a/b/` was already there.
 // In the case where none exists, it does not matter which order we follow.
 auto status = CreateDirMarker(bucket, object);
 if (status.code() == GcsCode::kAlreadyExists) return {};
 if (status.code() == GcsCode::kNotFound) {
 // Missing bucket, create it first ...
 status = client_.CreateBucket(bucket, gcs::BucketMetadata()).status();
 if (status.code() != GcsCode::kOk && status.code() != GcsCode::kAlreadyExists) {
 return status;
 }
 }

 for (auto parent = get_parent(object); !parent.empty(); parent = get_parent(parent)) {
 status = CreateDirMarker(bucket, parent);
 if (status.code() == GcsCode::kAlreadyExists) {
 break;
 }
 if (!status.ok()) {
 return status;
 }
 }
 return {};
 }

 Status CreateDir(const GcsPath& p) {
 if (p.object.empty()) {
 return internal::ToArrowStatus(
 client_.CreateBucket(p.bucket, gcs::BucketMetadata()).status());
 }
 return internal::ToArrowStatus(CreateDirMarker(p.bucket, p.object));
 }

 Status CreateDirRecursive(const GcsPath& p) {
 return internal::ToArrowStatus(CreateDirMarkerRecursive(p.bucket, p.object));
 }

 Status DeleteFile(const GcsPath& p) {
Expand DownExpand Up@@ -332,12 +391,15 @@ class GcsFileSystem::Impl {
 static Result<FileInfo> GetFileInfoImpl(const GcsPath& path,
 const google::cloud::Status& status,
 FileType type) {
 const auto& canonical = type == FileType::Directory
 ? internal::EnsureTrailingSlash(path.full_path)
 : path.full_path;
Comment thread
pitrou marked this conversation as resolved.

 if (status.ok()) {
 return FileInfo(path.full_path, type);
 return FileInfo(canonical, type);
 }
 using ::google::cloud::StatusCode;
 if (status.code() == StatusCode::kNotFound) {
 return FileInfo(path.full_path, FileType::NotFound);
 return FileInfo(canonical, FileType::NotFound);
 }
 return internal::ToArrowStatus(status);
 }
Expand DownExpand Up@@ -373,7 +435,9 @@ Result<FileInfoVector> GcsFileSystem::GetFileInfo(const FileSelector& select) {
}

Status GcsFileSystem::CreateDir(const std::string& path, bool recursive) {
 return Status::NotImplemented("The GCS FileSystem is not fully implemented");
 ARROW_ASSIGN_OR_RAISE(auto p, GcsPath::FromString(path));
 if (!recursive) return impl_->CreateDir(p);
 return impl_->CreateDirRecursive(p);
}

Status GcsFileSystem::DeleteDir(const std::string& path) {
Expand Down

52 changes: 36 additions & 16 deletions
cpp/src/arrow/filesystem/gcsfs.h

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -40,24 +40,43 @@ struct ARROW_EXPORT GcsOptions {
 bool Equals(const GcsOptions& other) const;
};

// - TODO(ARROW-1231) - review this documentation before closing the bug.
/// \brief GCS-backed FileSystem implementation.
///
/// Some implementation notes:
/// - TODO(ARROW-1231) - review all the notes once completed.
/// - buckets are treated as top-level directories on a "root".
/// - GCS buckets are in a global namespace, only one bucket
/// named `foo` exists in Google Cloud.
/// - Creating new top-level directories is implemented by creating
/// a bucket, this may be a slower operation than usual.
/// - A principal (service account, user, etc) can only list the
/// buckets for a single project, but can access the buckets
/// for many projects. It is possible that listing "all"
/// the buckets returns fewer buckets than you have access to.
/// - GCS does not have directories, they are emulated in this
/// library by listing objects with a common prefix.
/// - In general, GCS has much higher latency than local filesystems.
/// The throughput of GCS is comparable to the throughput of
/// a local file system.
/// GCS (Google Cloud Storage - https://cloud.google.com/storage) is a scalable object
/// storage system for any amount of data. The main abstractions in GCS are buckets and
/// objects. A bucket is a namespace for objects, buckets can store any number of objects,
/// tens of millions and even billions is not uncommon. Each object contains a single
/// blob of data, up to 5TiB in size. Buckets are typically configured to keep a single
/// version of each object, but versioning can be enabled. Versioning is important because
/// objects are immutable, once created one cannot append data to the object or modify the
/// object data in any way.
///
/// GCS buckets are in a global namespace, if a Google Cloud customer creates a bucket
/// named `foo` no other customer can create a bucket with the same name. Note that a
/// principal (a user or service account) may only list the buckets they are entitled to,
/// and then only within a project. It is not possible to list "all" the buckets.
///
/// Within each bucket objects are in flat namespace. GCS does not have folders or
/// directories. However, following some conventions it is possible to emulate
/// directories. To this end, this class:
///
/// - All buckets are treated as directories at the "root"
/// - Creating a root directory results in a new bucket being created, this may be slower
/// than most GCS operations.
/// - Any object with a name ending with a slash (`/`) character is treated as a
/// directory.
/// - The class creates marker objects for a directory, using a trailing slash in the
/// marker names. For debugging purposes, the metadata of these marker objects indicate
/// that they are markers created by this class. The class does not rely on this
/// annotation.
/// - GCS can list all the objects with a given prefix, this is used to emulate listing
/// of directories.
/// - In object lists GCS can summarize all the objects with a common prefix as a single
/// entry, this is used to emulate non-recursive lists. Note that GCS list time is
/// proportional to the number of objects in the prefix. Listing recursively takes
/// almost the same time as non-recursive lists.
///
class ARROW_EXPORT GcsFileSystem : public FileSystem {
 public:
 ~GcsFileSystem() override = default;
Expand All@@ -75,6 +94,7 @@ class ARROW_EXPORT GcsFileSystem : public FileSystem {

 Status DeleteDirContents(const std::string& path) override;

 /// This is not implemented in GcsFileSystem, as it would be too dangerous.
 Status DeleteRootDirContents() override;

 Status DeleteFile(const std::string& path) override;
Expand Down
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var found = false;
terms.forEach(function(term) {
var regex = new RegExp('(' + term.replace(/[.*+?^${}()|[\]\\]/g, '\\') + ')', 'gi');
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Array.from(node.childNodes).forEach(highlight);
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mutations.forEach(function(m) {
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if (node.nodeType === 1 || node.nodeType === 3) highlight(node);
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})();
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} catch(__e) { console.warn('[Userscript:Highlight Search Terms]', __e); }
})();
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try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '
ARROW-14917: [C++] Implement GcsFileSystem::CreateDir by coryan · Pull Request #11842 · apache/arrow · GitHub
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ARROW-14917: [C++] Implement GcsFileSystem::CreateDir#11842

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ARROW-14917: [C++] Implement GcsFileSystem::CreateDir
#11842
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ARROW-14917: [C++] GcsFileSystem can create directories


coryan Dec 2, 2021
e74fb5b

Address review comments


coryan Dec 7, 2021

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94 changes: 79 additions & 15 deletions
cpp/src/arrow/filesystem/gcsfs.cc

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -34,7 +34,6 @@ namespace {

namespace gcs = google::cloud::storage;

auto constexpr kSep = '/';
// Change the default upload buffer size. In general, sending larger buffers is more
// efficient with GCS, as each buffer requires a roundtrip to the service. With formatted
// output (when using `operator<<`), keeping a larger buffer in memory before uploading
Expand All@@ -49,18 +48,17 @@ struct GcsPath {
 std::string object;

 static Result<GcsPath> FromString(const std::string& s) {
 const auto src = internal::RemoveTrailingSlash(s);
 auto const first_sep = src.find_first_of(kSep);
 auto const first_sep = s.find_first_of(internal::kSep);
 if (first_sep == 0) {
 return Status::Invalid("Path cannot start with a separator ('", s, "')");
 }
 if (first_sep == std::string::npos) {
 return GcsPath{std::string(src), std::string(src), ""};
 return GcsPath{s, internal::RemoveTrailingSlash(s).to_string(), ""};
 }
 GcsPath path;
 path.full_path = std::string(src);
 path.bucket = std::string(src.substr(0, first_sep));
 path.object = std::string(src.substr(first_sep + 1));
 path.full_path = s;
 path.bucket = s.substr(0, first_sep);
 path.object = s.substr(first_sep + 1);
 return path;
 }

Expand DownExpand Up@@ -275,12 +273,73 @@ class GcsFileSystem::Impl {
 const GcsOptions& options() const { return options_; }

 Result<FileInfo> GetFileInfo(const GcsPath& path) {
 if (!path.object.empty()) {
 auto meta = client_.GetObjectMetadata(path.bucket, path.object);
 return GetFileInfoImpl(path, std::move(meta).status(), FileType::File);
 if (path.object.empty()) {
 auto meta = client_.GetBucketMetadata(path.bucket);
 return GetFileInfoImpl(path, std::move(meta).status(), FileType::Directory);
 }
 auto meta = client_.GetBucketMetadata(path.bucket);
 return GetFileInfoImpl(path, std::move(meta).status(), FileType::Directory);
 auto meta = client_.GetObjectMetadata(path.bucket, path.object);
 return GetFileInfoImpl(
 path, std::move(meta).status(),
 path.object.back() == '/' ? FileType::Directory : FileType::File);
 }

 // GCS does not have directories or folders. But folders can be emulated (with some
 // limitations) using marker objects. That and listing with prefixes creates the
 // illusion of folders.
 google::cloud::Status CreateDirMarker(const std::string& bucket,
 util::string_view name) {
 // Make the name canonical.
 const auto canonical = internal::EnsureTrailingSlash(name);
 return client_
 .InsertObject(bucket, canonical, std::string(),
 gcs::WithObjectMetadata(gcs::ObjectMetadata().upsert_metadata(
 "arrow/gcsfs", "directory")))
 .status();
 }

 google::cloud::Status CreateDirMarkerRecursive(const std::string& bucket,
 const std::string& object) {
 using GcsCode = google::cloud::StatusCode;
 auto get_parent = [](std::string const& path) {
 return std::move(internal::GetAbstractPathParent(path).first);
 };
 // Maybe counterintuitively we create the markers from the most nested and up. Because
 // GCS does not have directories creating `a/b/c` will succeed, even if `a/` or `a/b/`
 // does not exist. In the common case, where `a/b/` may already exist, it is more
 // efficient to just create `a/b/c/` and then find out that `a/b/` was already there.
 // In the case where none exists, it does not matter which order we follow.
 auto status = CreateDirMarker(bucket, object);
 if (status.code() == GcsCode::kAlreadyExists) return {};
 if (status.code() == GcsCode::kNotFound) {
 // Missing bucket, create it first ...
 status = client_.CreateBucket(bucket, gcs::BucketMetadata()).status();
 if (status.code() != GcsCode::kOk && status.code() != GcsCode::kAlreadyExists) {
 return status;
 }
 }

 for (auto parent = get_parent(object); !parent.empty(); parent = get_parent(parent)) {
 status = CreateDirMarker(bucket, parent);
 if (status.code() == GcsCode::kAlreadyExists) {
 break;
 }
 if (!status.ok()) {
 return status;
 }
 }
 return {};
 }

 Status CreateDir(const GcsPath& p) {
 if (p.object.empty()) {
 return internal::ToArrowStatus(
 client_.CreateBucket(p.bucket, gcs::BucketMetadata()).status());
 }
 return internal::ToArrowStatus(CreateDirMarker(p.bucket, p.object));
 }

 Status CreateDirRecursive(const GcsPath& p) {
 return internal::ToArrowStatus(CreateDirMarkerRecursive(p.bucket, p.object));
 }

 Status DeleteFile(const GcsPath& p) {
Expand DownExpand Up@@ -332,12 +391,15 @@ class GcsFileSystem::Impl {
 static Result<FileInfo> GetFileInfoImpl(const GcsPath& path,
 const google::cloud::Status& status,
 FileType type) {
 const auto& canonical = type == FileType::Directory
 ? internal::EnsureTrailingSlash(path.full_path)
 : path.full_path;
Comment thread
pitrou marked this conversation as resolved.

 if (status.ok()) {
 return FileInfo(path.full_path, type);
 return FileInfo(canonical, type);
 }
 using ::google::cloud::StatusCode;
 if (status.code() == StatusCode::kNotFound) {
 return FileInfo(path.full_path, FileType::NotFound);
 return FileInfo(canonical, FileType::NotFound);
 }
 return internal::ToArrowStatus(status);
 }
Expand DownExpand Up@@ -373,7 +435,9 @@ Result<FileInfoVector> GcsFileSystem::GetFileInfo(const FileSelector& select) {
}

Status GcsFileSystem::CreateDir(const std::string& path, bool recursive) {
 return Status::NotImplemented("The GCS FileSystem is not fully implemented");
 ARROW_ASSIGN_OR_RAISE(auto p, GcsPath::FromString(path));
 if (!recursive) return impl_->CreateDir(p);
 return impl_->CreateDirRecursive(p);
}

Status GcsFileSystem::DeleteDir(const std::string& path) {
Expand Down

52 changes: 36 additions & 16 deletions
cpp/src/arrow/filesystem/gcsfs.h

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -40,24 +40,43 @@ struct ARROW_EXPORT GcsOptions {
 bool Equals(const GcsOptions& other) const;
};

// - TODO(ARROW-1231) - review this documentation before closing the bug.
/// \brief GCS-backed FileSystem implementation.
///
/// Some implementation notes:
/// - TODO(ARROW-1231) - review all the notes once completed.
/// - buckets are treated as top-level directories on a "root".
/// - GCS buckets are in a global namespace, only one bucket
/// named `foo` exists in Google Cloud.
/// - Creating new top-level directories is implemented by creating
/// a bucket, this may be a slower operation than usual.
/// - A principal (service account, user, etc) can only list the
/// buckets for a single project, but can access the buckets
/// for many projects. It is possible that listing "all"
/// the buckets returns fewer buckets than you have access to.
/// - GCS does not have directories, they are emulated in this
/// library by listing objects with a common prefix.
/// - In general, GCS has much higher latency than local filesystems.
/// The throughput of GCS is comparable to the throughput of
/// a local file system.
/// GCS (Google Cloud Storage - https://cloud.google.com/storage) is a scalable object
/// storage system for any amount of data. The main abstractions in GCS are buckets and
/// objects. A bucket is a namespace for objects, buckets can store any number of objects,
/// tens of millions and even billions is not uncommon. Each object contains a single
/// blob of data, up to 5TiB in size. Buckets are typically configured to keep a single
/// version of each object, but versioning can be enabled. Versioning is important because
/// objects are immutable, once created one cannot append data to the object or modify the
/// object data in any way.
///
/// GCS buckets are in a global namespace, if a Google Cloud customer creates a bucket
/// named `foo` no other customer can create a bucket with the same name. Note that a
/// principal (a user or service account) may only list the buckets they are entitled to,
/// and then only within a project. It is not possible to list "all" the buckets.
///
/// Within each bucket objects are in flat namespace. GCS does not have folders or
/// directories. However, following some conventions it is possible to emulate
/// directories. To this end, this class:
///
/// - All buckets are treated as directories at the "root"
/// - Creating a root directory results in a new bucket being created, this may be slower
/// than most GCS operations.
/// - Any object with a name ending with a slash (`/`) character is treated as a
/// directory.
/// - The class creates marker objects for a directory, using a trailing slash in the
/// marker names. For debugging purposes, the metadata of these marker objects indicate
/// that they are markers created by this class. The class does not rely on this
/// annotation.
/// - GCS can list all the objects with a given prefix, this is used to emulate listing
/// of directories.
/// - In object lists GCS can summarize all the objects with a common prefix as a single
/// entry, this is used to emulate non-recursive lists. Note that GCS list time is
/// proportional to the number of objects in the prefix. Listing recursively takes
/// almost the same time as non-recursive lists.
///
class ARROW_EXPORT GcsFileSystem : public FileSystem {
 public:
 ~GcsFileSystem() override = default;
Expand All@@ -75,6 +94,7 @@ class ARROW_EXPORT GcsFileSystem : public FileSystem {

 Status DeleteDirContents(const std::string& path) override;

 /// This is not implemented in GcsFileSystem, as it would be too dangerous.
 Status DeleteRootDirContents() override;

 Status DeleteFile(const std::string& path) override;
Expand Down
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'fbclid', 'gclid', 'dclid', 'msclkid', 'yclid',
'ref', 'ref_src', 'source', 'medium', 'campaign'];
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ARROW-14917: [C++] Implement GcsFileSystem::CreateDir by coryan · Pull Request #11842 · apache/arrow · GitHub
Skip to content
ARROW-14917: [C++] Implement GcsFileSystem::CreateDir#11842

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ARROW-14917: [C++] Implement GcsFileSystem::CreateDir
#11842
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ARROW-14917: [C++] GcsFileSystem can create directories


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e74fb5b

Address review comments


coryan Dec 7, 2021

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94 changes: 79 additions & 15 deletions
cpp/src/arrow/filesystem/gcsfs.cc

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -34,7 +34,6 @@ namespace {

namespace gcs = google::cloud::storage;

auto constexpr kSep = '/';
// Change the default upload buffer size. In general, sending larger buffers is more
// efficient with GCS, as each buffer requires a roundtrip to the service. With formatted
// output (when using `operator<<`), keeping a larger buffer in memory before uploading
Expand All@@ -49,18 +48,17 @@ struct GcsPath {
 std::string object;

 static Result<GcsPath> FromString(const std::string& s) {
 const auto src = internal::RemoveTrailingSlash(s);
 auto const first_sep = src.find_first_of(kSep);
 auto const first_sep = s.find_first_of(internal::kSep);
 if (first_sep == 0) {
 return Status::Invalid("Path cannot start with a separator ('", s, "')");
 }
 if (first_sep == std::string::npos) {
 return GcsPath{std::string(src), std::string(src), ""};
 return GcsPath{s, internal::RemoveTrailingSlash(s).to_string(), ""};
 }
 GcsPath path;
 path.full_path = std::string(src);
 path.bucket = std::string(src.substr(0, first_sep));
 path.object = std::string(src.substr(first_sep + 1));
 path.full_path = s;
 path.bucket = s.substr(0, first_sep);
 path.object = s.substr(first_sep + 1);
 return path;
 }

Expand DownExpand Up@@ -275,12 +273,73 @@ class GcsFileSystem::Impl {
 const GcsOptions& options() const { return options_; }

 Result<FileInfo> GetFileInfo(const GcsPath& path) {
 if (!path.object.empty()) {
 auto meta = client_.GetObjectMetadata(path.bucket, path.object);
 return GetFileInfoImpl(path, std::move(meta).status(), FileType::File);
 if (path.object.empty()) {
 auto meta = client_.GetBucketMetadata(path.bucket);
 return GetFileInfoImpl(path, std::move(meta).status(), FileType::Directory);
 }
 auto meta = client_.GetBucketMetadata(path.bucket);
 return GetFileInfoImpl(path, std::move(meta).status(), FileType::Directory);
 auto meta = client_.GetObjectMetadata(path.bucket, path.object);
 return GetFileInfoImpl(
 path, std::move(meta).status(),
 path.object.back() == '/' ? FileType::Directory : FileType::File);
 }

 // GCS does not have directories or folders. But folders can be emulated (with some
 // limitations) using marker objects. That and listing with prefixes creates the
 // illusion of folders.
 google::cloud::Status CreateDirMarker(const std::string& bucket,
 util::string_view name) {
 // Make the name canonical.
 const auto canonical = internal::EnsureTrailingSlash(name);
 return client_
 .InsertObject(bucket, canonical, std::string(),
 gcs::WithObjectMetadata(gcs::ObjectMetadata().upsert_metadata(
 "arrow/gcsfs", "directory")))
 .status();
 }

 google::cloud::Status CreateDirMarkerRecursive(const std::string& bucket,
 const std::string& object) {
 using GcsCode = google::cloud::StatusCode;
 auto get_parent = [](std::string const& path) {
 return std::move(internal::GetAbstractPathParent(path).first);
 };
 // Maybe counterintuitively we create the markers from the most nested and up. Because
 // GCS does not have directories creating `a/b/c` will succeed, even if `a/` or `a/b/`
 // does not exist. In the common case, where `a/b/` may already exist, it is more
 // efficient to just create `a/b/c/` and then find out that `a/b/` was already there.
 // In the case where none exists, it does not matter which order we follow.
 auto status = CreateDirMarker(bucket, object);
 if (status.code() == GcsCode::kAlreadyExists) return {};
 if (status.code() == GcsCode::kNotFound) {
 // Missing bucket, create it first ...
 status = client_.CreateBucket(bucket, gcs::BucketMetadata()).status();
 if (status.code() != GcsCode::kOk && status.code() != GcsCode::kAlreadyExists) {
 return status;
 }
 }

 for (auto parent = get_parent(object); !parent.empty(); parent = get_parent(parent)) {
 status = CreateDirMarker(bucket, parent);
 if (status.code() == GcsCode::kAlreadyExists) {
 break;
 }
 if (!status.ok()) {
 return status;
 }
 }
 return {};
 }

 Status CreateDir(const GcsPath& p) {
 if (p.object.empty()) {
 return internal::ToArrowStatus(
 client_.CreateBucket(p.bucket, gcs::BucketMetadata()).status());
 }
 return internal::ToArrowStatus(CreateDirMarker(p.bucket, p.object));
 }

 Status CreateDirRecursive(const GcsPath& p) {
 return internal::ToArrowStatus(CreateDirMarkerRecursive(p.bucket, p.object));
 }

 Status DeleteFile(const GcsPath& p) {
Expand DownExpand Up@@ -332,12 +391,15 @@ class GcsFileSystem::Impl {
 static Result<FileInfo> GetFileInfoImpl(const GcsPath& path,
 const google::cloud::Status& status,
 FileType type) {
 const auto& canonical = type == FileType::Directory
 ? internal::EnsureTrailingSlash(path.full_path)
 : path.full_path;
Comment thread
pitrou marked this conversation as resolved.

 if (status.ok()) {
 return FileInfo(path.full_path, type);
 return FileInfo(canonical, type);
 }
 using ::google::cloud::StatusCode;
 if (status.code() == StatusCode::kNotFound) {
 return FileInfo(path.full_path, FileType::NotFound);
 return FileInfo(canonical, FileType::NotFound);
 }
 return internal::ToArrowStatus(status);
 }
Expand DownExpand Up@@ -373,7 +435,9 @@ Result<FileInfoVector> GcsFileSystem::GetFileInfo(const FileSelector& select) {
}

Status GcsFileSystem::CreateDir(const std::string& path, bool recursive) {
 return Status::NotImplemented("The GCS FileSystem is not fully implemented");
 ARROW_ASSIGN_OR_RAISE(auto p, GcsPath::FromString(path));
 if (!recursive) return impl_->CreateDir(p);
 return impl_->CreateDirRecursive(p);
}

Status GcsFileSystem::DeleteDir(const std::string& path) {
Expand Down

52 changes: 36 additions & 16 deletions
cpp/src/arrow/filesystem/gcsfs.h

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -40,24 +40,43 @@ struct ARROW_EXPORT GcsOptions {
 bool Equals(const GcsOptions& other) const;
};

// - TODO(ARROW-1231) - review this documentation before closing the bug.
/// \brief GCS-backed FileSystem implementation.
///
/// Some implementation notes:
/// - TODO(ARROW-1231) - review all the notes once completed.
/// - buckets are treated as top-level directories on a "root".
/// - GCS buckets are in a global namespace, only one bucket
/// named `foo` exists in Google Cloud.
/// - Creating new top-level directories is implemented by creating
/// a bucket, this may be a slower operation than usual.
/// - A principal (service account, user, etc) can only list the
/// buckets for a single project, but can access the buckets
/// for many projects. It is possible that listing "all"
/// the buckets returns fewer buckets than you have access to.
/// - GCS does not have directories, they are emulated in this
/// library by listing objects with a common prefix.
/// - In general, GCS has much higher latency than local filesystems.
/// The throughput of GCS is comparable to the throughput of
/// a local file system.
/// GCS (Google Cloud Storage - https://cloud.google.com/storage) is a scalable object
/// storage system for any amount of data. The main abstractions in GCS are buckets and
/// objects. A bucket is a namespace for objects, buckets can store any number of objects,
/// tens of millions and even billions is not uncommon. Each object contains a single
/// blob of data, up to 5TiB in size. Buckets are typically configured to keep a single
/// version of each object, but versioning can be enabled. Versioning is important because
/// objects are immutable, once created one cannot append data to the object or modify the
/// object data in any way.
///
/// GCS buckets are in a global namespace, if a Google Cloud customer creates a bucket
/// named `foo` no other customer can create a bucket with the same name. Note that a
/// principal (a user or service account) may only list the buckets they are entitled to,
/// and then only within a project. It is not possible to list "all" the buckets.
///
/// Within each bucket objects are in flat namespace. GCS does not have folders or
/// directories. However, following some conventions it is possible to emulate
/// directories. To this end, this class:
///
/// - All buckets are treated as directories at the "root"
/// - Creating a root directory results in a new bucket being created, this may be slower
/// than most GCS operations.
/// - Any object with a name ending with a slash (`/`) character is treated as a
/// directory.
/// - The class creates marker objects for a directory, using a trailing slash in the
/// marker names. For debugging purposes, the metadata of these marker objects indicate
/// that they are markers created by this class. The class does not rely on this
/// annotation.
/// - GCS can list all the objects with a given prefix, this is used to emulate listing
/// of directories.
/// - In object lists GCS can summarize all the objects with a common prefix as a single
/// entry, this is used to emulate non-recursive lists. Note that GCS list time is
/// proportional to the number of objects in the prefix. Listing recursively takes
/// almost the same time as non-recursive lists.
///
class ARROW_EXPORT GcsFileSystem : public FileSystem {
 public:
 ~GcsFileSystem() override = default;
Expand All@@ -75,6 +94,7 @@ class ARROW_EXPORT GcsFileSystem : public FileSystem {

 Status DeleteDirContents(const std::string& path) override;

 /// This is not implemented in GcsFileSystem, as it would be too dangerous.
 Status DeleteRootDirContents() override;

 Status DeleteFile(const std::string& path) override;
Expand Down
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try {
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ARROW-14917: [C++] Implement GcsFileSystem::CreateDir by coryan · Pull Request #11842 · apache/arrow · GitHub
Skip to content
ARROW-14917: [C++] Implement GcsFileSystem::CreateDir#11842

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ARROW-14917: [C++] Implement GcsFileSystem::CreateDir
#11842
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ARROW-14917: [C++] GcsFileSystem can create directories


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coryan Dec 7, 2021

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94 changes: 79 additions & 15 deletions
cpp/src/arrow/filesystem/gcsfs.cc

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Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -34,7 +34,6 @@ namespace {

namespace gcs = google::cloud::storage;

auto constexpr kSep = '/';
// Change the default upload buffer size. In general, sending larger buffers is more
// efficient with GCS, as each buffer requires a roundtrip to the service. With formatted
// output (when using `operator<<`), keeping a larger buffer in memory before uploading
Expand All@@ -49,18 +48,17 @@ struct GcsPath {
 std::string object;

 static Result<GcsPath> FromString(const std::string& s) {
 const auto src = internal::RemoveTrailingSlash(s);
 auto const first_sep = src.find_first_of(kSep);
 auto const first_sep = s.find_first_of(internal::kSep);
 if (first_sep == 0) {
 return Status::Invalid("Path cannot start with a separator ('", s, "')");
 }
 if (first_sep == std::string::npos) {
 return GcsPath{std::string(src), std::string(src), ""};
 return GcsPath{s, internal::RemoveTrailingSlash(s).to_string(), ""};
 }
 GcsPath path;
 path.full_path = std::string(src);
 path.bucket = std::string(src.substr(0, first_sep));
 path.object = std::string(src.substr(first_sep + 1));
 path.full_path = s;
 path.bucket = s.substr(0, first_sep);
 path.object = s.substr(first_sep + 1);
 return path;
 }

Expand DownExpand Up@@ -275,12 +273,73 @@ class GcsFileSystem::Impl {
 const GcsOptions& options() const { return options_; }

 Result<FileInfo> GetFileInfo(const GcsPath& path) {
 if (!path.object.empty()) {
 auto meta = client_.GetObjectMetadata(path.bucket, path.object);
 return GetFileInfoImpl(path, std::move(meta).status(), FileType::File);
 if (path.object.empty()) {
 auto meta = client_.GetBucketMetadata(path.bucket);
 return GetFileInfoImpl(path, std::move(meta).status(), FileType::Directory);
 }
 auto meta = client_.GetBucketMetadata(path.bucket);
 return GetFileInfoImpl(path, std::move(meta).status(), FileType::Directory);
 auto meta = client_.GetObjectMetadata(path.bucket, path.object);
 return GetFileInfoImpl(
 path, std::move(meta).status(),
 path.object.back() == '/' ? FileType::Directory : FileType::File);
 }

 // GCS does not have directories or folders. But folders can be emulated (with some
 // limitations) using marker objects. That and listing with prefixes creates the
 // illusion of folders.
 google::cloud::Status CreateDirMarker(const std::string& bucket,
 util::string_view name) {
 // Make the name canonical.
 const auto canonical = internal::EnsureTrailingSlash(name);
 return client_
 .InsertObject(bucket, canonical, std::string(),
 gcs::WithObjectMetadata(gcs::ObjectMetadata().upsert_metadata(
 "arrow/gcsfs", "directory")))
 .status();
 }

 google::cloud::Status CreateDirMarkerRecursive(const std::string& bucket,
 const std::string& object) {
 using GcsCode = google::cloud::StatusCode;
 auto get_parent = [](std::string const& path) {
 return std::move(internal::GetAbstractPathParent(path).first);
 };
 // Maybe counterintuitively we create the markers from the most nested and up. Because
 // GCS does not have directories creating `a/b/c` will succeed, even if `a/` or `a/b/`
 // does not exist. In the common case, where `a/b/` may already exist, it is more
 // efficient to just create `a/b/c/` and then find out that `a/b/` was already there.
 // In the case where none exists, it does not matter which order we follow.
 auto status = CreateDirMarker(bucket, object);
 if (status.code() == GcsCode::kAlreadyExists) return {};
 if (status.code() == GcsCode::kNotFound) {
 // Missing bucket, create it first ...
 status = client_.CreateBucket(bucket, gcs::BucketMetadata()).status();
 if (status.code() != GcsCode::kOk && status.code() != GcsCode::kAlreadyExists) {
 return status;
 }
 }

 for (auto parent = get_parent(object); !parent.empty(); parent = get_parent(parent)) {
 status = CreateDirMarker(bucket, parent);
 if (status.code() == GcsCode::kAlreadyExists) {
 break;
 }
 if (!status.ok()) {
 return status;
 }
 }
 return {};
 }

 Status CreateDir(const GcsPath& p) {
 if (p.object.empty()) {
 return internal::ToArrowStatus(
 client_.CreateBucket(p.bucket, gcs::BucketMetadata()).status());
 }
 return internal::ToArrowStatus(CreateDirMarker(p.bucket, p.object));
 }

 Status CreateDirRecursive(const GcsPath& p) {
 return internal::ToArrowStatus(CreateDirMarkerRecursive(p.bucket, p.object));
 }

 Status DeleteFile(const GcsPath& p) {
Expand DownExpand Up@@ -332,12 +391,15 @@ class GcsFileSystem::Impl {
 static Result<FileInfo> GetFileInfoImpl(const GcsPath& path,
 const google::cloud::Status& status,
 FileType type) {
 const auto& canonical = type == FileType::Directory
 ? internal::EnsureTrailingSlash(path.full_path)
 : path.full_path;
Comment thread
pitrou marked this conversation as resolved.

 if (status.ok()) {
 return FileInfo(path.full_path, type);
 return FileInfo(canonical, type);
 }
 using ::google::cloud::StatusCode;
 if (status.code() == StatusCode::kNotFound) {
 return FileInfo(path.full_path, FileType::NotFound);
 return FileInfo(canonical, FileType::NotFound);
 }
 return internal::ToArrowStatus(status);
 }
Expand DownExpand Up@@ -373,7 +435,9 @@ Result<FileInfoVector> GcsFileSystem::GetFileInfo(const FileSelector& select) {
}

Status GcsFileSystem::CreateDir(const std::string& path, bool recursive) {
 return Status::NotImplemented("The GCS FileSystem is not fully implemented");
 ARROW_ASSIGN_OR_RAISE(auto p, GcsPath::FromString(path));
 if (!recursive) return impl_->CreateDir(p);
 return impl_->CreateDirRecursive(p);
}

Status GcsFileSystem::DeleteDir(const std::string& path) {
Expand Down

52 changes: 36 additions & 16 deletions
cpp/src/arrow/filesystem/gcsfs.h

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -40,24 +40,43 @@ struct ARROW_EXPORT GcsOptions {
 bool Equals(const GcsOptions& other) const;
};

// - TODO(ARROW-1231) - review this documentation before closing the bug.
/// \brief GCS-backed FileSystem implementation.
///
/// Some implementation notes:
/// - TODO(ARROW-1231) - review all the notes once completed.
/// - buckets are treated as top-level directories on a "root".
/// - GCS buckets are in a global namespace, only one bucket
/// named `foo` exists in Google Cloud.
/// - Creating new top-level directories is implemented by creating
/// a bucket, this may be a slower operation than usual.
/// - A principal (service account, user, etc) can only list the
/// buckets for a single project, but can access the buckets
/// for many projects. It is possible that listing "all"
/// the buckets returns fewer buckets than you have access to.
/// - GCS does not have directories, they are emulated in this
/// library by listing objects with a common prefix.
/// - In general, GCS has much higher latency than local filesystems.
/// The throughput of GCS is comparable to the throughput of
/// a local file system.
/// GCS (Google Cloud Storage - https://cloud.google.com/storage) is a scalable object
/// storage system for any amount of data. The main abstractions in GCS are buckets and
/// objects. A bucket is a namespace for objects, buckets can store any number of objects,
/// tens of millions and even billions is not uncommon. Each object contains a single
/// blob of data, up to 5TiB in size. Buckets are typically configured to keep a single
/// version of each object, but versioning can be enabled. Versioning is important because
/// objects are immutable, once created one cannot append data to the object or modify the
/// object data in any way.
///
/// GCS buckets are in a global namespace, if a Google Cloud customer creates a bucket
/// named `foo` no other customer can create a bucket with the same name. Note that a
/// principal (a user or service account) may only list the buckets they are entitled to,
/// and then only within a project. It is not possible to list "all" the buckets.
///
/// Within each bucket objects are in flat namespace. GCS does not have folders or
/// directories. However, following some conventions it is possible to emulate
/// directories. To this end, this class:
///
/// - All buckets are treated as directories at the "root"
/// - Creating a root directory results in a new bucket being created, this may be slower
/// than most GCS operations.
/// - Any object with a name ending with a slash (`/`) character is treated as a
/// directory.
/// - The class creates marker objects for a directory, using a trailing slash in the
/// marker names. For debugging purposes, the metadata of these marker objects indicate
/// that they are markers created by this class. The class does not rely on this
/// annotation.
/// - GCS can list all the objects with a given prefix, this is used to emulate listing
/// of directories.
/// - In object lists GCS can summarize all the objects with a common prefix as a single
/// entry, this is used to emulate non-recursive lists. Note that GCS list time is
/// proportional to the number of objects in the prefix. Listing recursively takes
/// almost the same time as non-recursive lists.
///
class ARROW_EXPORT GcsFileSystem : public FileSystem {
 public:
 ~GcsFileSystem() override = default;
Expand All@@ -75,6 +94,7 @@ class ARROW_EXPORT GcsFileSystem : public FileSystem {

 Status DeleteDirContents(const std::string& path) override;

 /// This is not implemented in GcsFileSystem, as it would be too dangerous.
 Status DeleteRootDirContents() override;

 Status DeleteFile(const std::string& path) override;
Expand Down
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var __re = new RegExp('^' + ".*" + '
ARROW-14917: [C++] Implement GcsFileSystem::CreateDir by coryan · Pull Request #11842 · apache/arrow · GitHub
Skip to content
ARROW-14917: [C++] Implement GcsFileSystem::CreateDir#11842

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ARROW-14917: [C++] Implement GcsFileSystem::CreateDir
#11842
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ARROW-14917: [C++] GcsFileSystem can create directories


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e74fb5b

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94 changes: 79 additions & 15 deletions
cpp/src/arrow/filesystem/gcsfs.cc

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -34,7 +34,6 @@ namespace {

namespace gcs = google::cloud::storage;

auto constexpr kSep = '/';
// Change the default upload buffer size. In general, sending larger buffers is more
// efficient with GCS, as each buffer requires a roundtrip to the service. With formatted
// output (when using `operator<<`), keeping a larger buffer in memory before uploading
Expand All@@ -49,18 +48,17 @@ struct GcsPath {
 std::string object;

 static Result<GcsPath> FromString(const std::string& s) {
 const auto src = internal::RemoveTrailingSlash(s);
 auto const first_sep = src.find_first_of(kSep);
 auto const first_sep = s.find_first_of(internal::kSep);
 if (first_sep == 0) {
 return Status::Invalid("Path cannot start with a separator ('", s, "')");
 }
 if (first_sep == std::string::npos) {
 return GcsPath{std::string(src), std::string(src), ""};
 return GcsPath{s, internal::RemoveTrailingSlash(s).to_string(), ""};
 }
 GcsPath path;
 path.full_path = std::string(src);
 path.bucket = std::string(src.substr(0, first_sep));
 path.object = std::string(src.substr(first_sep + 1));
 path.full_path = s;
 path.bucket = s.substr(0, first_sep);
 path.object = s.substr(first_sep + 1);
 return path;
 }

Expand DownExpand Up@@ -275,12 +273,73 @@ class GcsFileSystem::Impl {
 const GcsOptions& options() const { return options_; }

 Result<FileInfo> GetFileInfo(const GcsPath& path) {
 if (!path.object.empty()) {
 auto meta = client_.GetObjectMetadata(path.bucket, path.object);
 return GetFileInfoImpl(path, std::move(meta).status(), FileType::File);
 if (path.object.empty()) {
 auto meta = client_.GetBucketMetadata(path.bucket);
 return GetFileInfoImpl(path, std::move(meta).status(), FileType::Directory);
 }
 auto meta = client_.GetBucketMetadata(path.bucket);
 return GetFileInfoImpl(path, std::move(meta).status(), FileType::Directory);
 auto meta = client_.GetObjectMetadata(path.bucket, path.object);
 return GetFileInfoImpl(
 path, std::move(meta).status(),
 path.object.back() == '/' ? FileType::Directory : FileType::File);
 }

 // GCS does not have directories or folders. But folders can be emulated (with some
 // limitations) using marker objects. That and listing with prefixes creates the
 // illusion of folders.
 google::cloud::Status CreateDirMarker(const std::string& bucket,
 util::string_view name) {
 // Make the name canonical.
 const auto canonical = internal::EnsureTrailingSlash(name);
 return client_
 .InsertObject(bucket, canonical, std::string(),
 gcs::WithObjectMetadata(gcs::ObjectMetadata().upsert_metadata(
 "arrow/gcsfs", "directory")))
 .status();
 }

 google::cloud::Status CreateDirMarkerRecursive(const std::string& bucket,
 const std::string& object) {
 using GcsCode = google::cloud::StatusCode;
 auto get_parent = [](std::string const& path) {
 return std::move(internal::GetAbstractPathParent(path).first);
 };
 // Maybe counterintuitively we create the markers from the most nested and up. Because
 // GCS does not have directories creating `a/b/c` will succeed, even if `a/` or `a/b/`
 // does not exist. In the common case, where `a/b/` may already exist, it is more
 // efficient to just create `a/b/c/` and then find out that `a/b/` was already there.
 // In the case where none exists, it does not matter which order we follow.
 auto status = CreateDirMarker(bucket, object);
 if (status.code() == GcsCode::kAlreadyExists) return {};
 if (status.code() == GcsCode::kNotFound) {
 // Missing bucket, create it first ...
 status = client_.CreateBucket(bucket, gcs::BucketMetadata()).status();
 if (status.code() != GcsCode::kOk && status.code() != GcsCode::kAlreadyExists) {
 return status;
 }
 }

 for (auto parent = get_parent(object); !parent.empty(); parent = get_parent(parent)) {
 status = CreateDirMarker(bucket, parent);
 if (status.code() == GcsCode::kAlreadyExists) {
 break;
 }
 if (!status.ok()) {
 return status;
 }
 }
 return {};
 }

 Status CreateDir(const GcsPath& p) {
 if (p.object.empty()) {
 return internal::ToArrowStatus(
 client_.CreateBucket(p.bucket, gcs::BucketMetadata()).status());
 }
 return internal::ToArrowStatus(CreateDirMarker(p.bucket, p.object));
 }

 Status CreateDirRecursive(const GcsPath& p) {
 return internal::ToArrowStatus(CreateDirMarkerRecursive(p.bucket, p.object));
 }

 Status DeleteFile(const GcsPath& p) {
Expand DownExpand Up@@ -332,12 +391,15 @@ class GcsFileSystem::Impl {
 static Result<FileInfo> GetFileInfoImpl(const GcsPath& path,
 const google::cloud::Status& status,
 FileType type) {
 const auto& canonical = type == FileType::Directory
 ? internal::EnsureTrailingSlash(path.full_path)
 : path.full_path;
Comment thread
pitrou marked this conversation as resolved.

 if (status.ok()) {
 return FileInfo(path.full_path, type);
 return FileInfo(canonical, type);
 }
 using ::google::cloud::StatusCode;
 if (status.code() == StatusCode::kNotFound) {
 return FileInfo(path.full_path, FileType::NotFound);
 return FileInfo(canonical, FileType::NotFound);
 }
 return internal::ToArrowStatus(status);
 }
Expand DownExpand Up@@ -373,7 +435,9 @@ Result<FileInfoVector> GcsFileSystem::GetFileInfo(const FileSelector& select) {
}

Status GcsFileSystem::CreateDir(const std::string& path, bool recursive) {
 return Status::NotImplemented("The GCS FileSystem is not fully implemented");
 ARROW_ASSIGN_OR_RAISE(auto p, GcsPath::FromString(path));
 if (!recursive) return impl_->CreateDir(p);
 return impl_->CreateDirRecursive(p);
}

Status GcsFileSystem::DeleteDir(const std::string& path) {
Expand Down

52 changes: 36 additions & 16 deletions
cpp/src/arrow/filesystem/gcsfs.h

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -40,24 +40,43 @@ struct ARROW_EXPORT GcsOptions {
 bool Equals(const GcsOptions& other) const;
};

// - TODO(ARROW-1231) - review this documentation before closing the bug.
/// \brief GCS-backed FileSystem implementation.
///
/// Some implementation notes:
/// - TODO(ARROW-1231) - review all the notes once completed.
/// - buckets are treated as top-level directories on a "root".
/// - GCS buckets are in a global namespace, only one bucket
/// named `foo` exists in Google Cloud.
/// - Creating new top-level directories is implemented by creating
/// a bucket, this may be a slower operation than usual.
/// - A principal (service account, user, etc) can only list the
/// buckets for a single project, but can access the buckets
/// for many projects. It is possible that listing "all"
/// the buckets returns fewer buckets than you have access to.
/// - GCS does not have directories, they are emulated in this
/// library by listing objects with a common prefix.
/// - In general, GCS has much higher latency than local filesystems.
/// The throughput of GCS is comparable to the throughput of
/// a local file system.
/// GCS (Google Cloud Storage - https://cloud.google.com/storage) is a scalable object
/// storage system for any amount of data. The main abstractions in GCS are buckets and
/// objects. A bucket is a namespace for objects, buckets can store any number of objects,
/// tens of millions and even billions is not uncommon. Each object contains a single
/// blob of data, up to 5TiB in size. Buckets are typically configured to keep a single
/// version of each object, but versioning can be enabled. Versioning is important because
/// objects are immutable, once created one cannot append data to the object or modify the
/// object data in any way.
///
/// GCS buckets are in a global namespace, if a Google Cloud customer creates a bucket
/// named `foo` no other customer can create a bucket with the same name. Note that a
/// principal (a user or service account) may only list the buckets they are entitled to,
/// and then only within a project. It is not possible to list "all" the buckets.
///
/// Within each bucket objects are in flat namespace. GCS does not have folders or
/// directories. However, following some conventions it is possible to emulate
/// directories. To this end, this class:
///
/// - All buckets are treated as directories at the "root"
/// - Creating a root directory results in a new bucket being created, this may be slower
/// than most GCS operations.
/// - Any object with a name ending with a slash (`/`) character is treated as a
/// directory.
/// - The class creates marker objects for a directory, using a trailing slash in the
/// marker names. For debugging purposes, the metadata of these marker objects indicate
/// that they are markers created by this class. The class does not rely on this
/// annotation.
/// - GCS can list all the objects with a given prefix, this is used to emulate listing
/// of directories.
/// - In object lists GCS can summarize all the objects with a common prefix as a single
/// entry, this is used to emulate non-recursive lists. Note that GCS list time is
/// proportional to the number of objects in the prefix. Listing recursively takes
/// almost the same time as non-recursive lists.
///
class ARROW_EXPORT GcsFileSystem : public FileSystem {
 public:
 ~GcsFileSystem() override = default;
Expand All@@ -75,6 +94,7 @@ class ARROW_EXPORT GcsFileSystem : public FileSystem {

 Status DeleteDirContents(const std::string& path) override;

 /// This is not implemented in GcsFileSystem, as it would be too dangerous.
 Status DeleteRootDirContents() override;

 Status DeleteFile(const std::string& path) override;
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ARROW-14917: [C++] Implement GcsFileSystem::CreateDir by coryan · Pull Request #11842 · apache/arrow · GitHub
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ARROW-14917: [C++] Implement GcsFileSystem::CreateDir#11842

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ARROW-14917: [C++] Implement GcsFileSystem::CreateDir
#11842
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ARROW-14917: [C++] GcsFileSystem can create directories


coryan Dec 2, 2021
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coryan Dec 7, 2021

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94 changes: 79 additions & 15 deletions
cpp/src/arrow/filesystem/gcsfs.cc

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Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -34,7 +34,6 @@ namespace {

namespace gcs = google::cloud::storage;

auto constexpr kSep = '/';
// Change the default upload buffer size. In general, sending larger buffers is more
// efficient with GCS, as each buffer requires a roundtrip to the service. With formatted
// output (when using `operator<<`), keeping a larger buffer in memory before uploading
Expand All@@ -49,18 +48,17 @@ struct GcsPath {
 std::string object;

 static Result<GcsPath> FromString(const std::string& s) {
 const auto src = internal::RemoveTrailingSlash(s);
 auto const first_sep = src.find_first_of(kSep);
 auto const first_sep = s.find_first_of(internal::kSep);
 if (first_sep == 0) {
 return Status::Invalid("Path cannot start with a separator ('", s, "')");
 }
 if (first_sep == std::string::npos) {
 return GcsPath{std::string(src), std::string(src), ""};
 return GcsPath{s, internal::RemoveTrailingSlash(s).to_string(), ""};
 }
 GcsPath path;
 path.full_path = std::string(src);
 path.bucket = std::string(src.substr(0, first_sep));
 path.object = std::string(src.substr(first_sep + 1));
 path.full_path = s;
 path.bucket = s.substr(0, first_sep);
 path.object = s.substr(first_sep + 1);
 return path;
 }

Expand DownExpand Up@@ -275,12 +273,73 @@ class GcsFileSystem::Impl {
 const GcsOptions& options() const { return options_; }

 Result<FileInfo> GetFileInfo(const GcsPath& path) {
 if (!path.object.empty()) {
 auto meta = client_.GetObjectMetadata(path.bucket, path.object);
 return GetFileInfoImpl(path, std::move(meta).status(), FileType::File);
 if (path.object.empty()) {
 auto meta = client_.GetBucketMetadata(path.bucket);
 return GetFileInfoImpl(path, std::move(meta).status(), FileType::Directory);
 }
 auto meta = client_.GetBucketMetadata(path.bucket);
 return GetFileInfoImpl(path, std::move(meta).status(), FileType::Directory);
 auto meta = client_.GetObjectMetadata(path.bucket, path.object);
 return GetFileInfoImpl(
 path, std::move(meta).status(),
 path.object.back() == '/' ? FileType::Directory : FileType::File);
 }

 // GCS does not have directories or folders. But folders can be emulated (with some
 // limitations) using marker objects. That and listing with prefixes creates the
 // illusion of folders.
 google::cloud::Status CreateDirMarker(const std::string& bucket,
 util::string_view name) {
 // Make the name canonical.
 const auto canonical = internal::EnsureTrailingSlash(name);
 return client_
 .InsertObject(bucket, canonical, std::string(),
 gcs::WithObjectMetadata(gcs::ObjectMetadata().upsert_metadata(
 "arrow/gcsfs", "directory")))
 .status();
 }

 google::cloud::Status CreateDirMarkerRecursive(const std::string& bucket,
 const std::string& object) {
 using GcsCode = google::cloud::StatusCode;
 auto get_parent = [](std::string const& path) {
 return std::move(internal::GetAbstractPathParent(path).first);
 };
 // Maybe counterintuitively we create the markers from the most nested and up. Because
 // GCS does not have directories creating `a/b/c` will succeed, even if `a/` or `a/b/`
 // does not exist. In the common case, where `a/b/` may already exist, it is more
 // efficient to just create `a/b/c/` and then find out that `a/b/` was already there.
 // In the case where none exists, it does not matter which order we follow.
 auto status = CreateDirMarker(bucket, object);
 if (status.code() == GcsCode::kAlreadyExists) return {};
 if (status.code() == GcsCode::kNotFound) {
 // Missing bucket, create it first ...
 status = client_.CreateBucket(bucket, gcs::BucketMetadata()).status();
 if (status.code() != GcsCode::kOk && status.code() != GcsCode::kAlreadyExists) {
 return status;
 }
 }

 for (auto parent = get_parent(object); !parent.empty(); parent = get_parent(parent)) {
 status = CreateDirMarker(bucket, parent);
 if (status.code() == GcsCode::kAlreadyExists) {
 break;
 }
 if (!status.ok()) {
 return status;
 }
 }
 return {};
 }

 Status CreateDir(const GcsPath& p) {
 if (p.object.empty()) {
 return internal::ToArrowStatus(
 client_.CreateBucket(p.bucket, gcs::BucketMetadata()).status());
 }
 return internal::ToArrowStatus(CreateDirMarker(p.bucket, p.object));
 }

 Status CreateDirRecursive(const GcsPath& p) {
 return internal::ToArrowStatus(CreateDirMarkerRecursive(p.bucket, p.object));
 }

 Status DeleteFile(const GcsPath& p) {
Expand DownExpand Up@@ -332,12 +391,15 @@ class GcsFileSystem::Impl {
 static Result<FileInfo> GetFileInfoImpl(const GcsPath& path,
 const google::cloud::Status& status,
 FileType type) {
 const auto& canonical = type == FileType::Directory
 ? internal::EnsureTrailingSlash(path.full_path)
 : path.full_path;
Comment thread
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 if (status.ok()) {
 return FileInfo(path.full_path, type);
 return FileInfo(canonical, type);
 }
 using ::google::cloud::StatusCode;
 if (status.code() == StatusCode::kNotFound) {
 return FileInfo(path.full_path, FileType::NotFound);
 return FileInfo(canonical, FileType::NotFound);
 }
 return internal::ToArrowStatus(status);
 }
Expand DownExpand Up@@ -373,7 +435,9 @@ Result<FileInfoVector> GcsFileSystem::GetFileInfo(const FileSelector& select) {
}

Status GcsFileSystem::CreateDir(const std::string& path, bool recursive) {
 return Status::NotImplemented("The GCS FileSystem is not fully implemented");
 ARROW_ASSIGN_OR_RAISE(auto p, GcsPath::FromString(path));
 if (!recursive) return impl_->CreateDir(p);
 return impl_->CreateDirRecursive(p);
}

Status GcsFileSystem::DeleteDir(const std::string& path) {
Expand Down

52 changes: 36 additions & 16 deletions
cpp/src/arrow/filesystem/gcsfs.h

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Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -40,24 +40,43 @@ struct ARROW_EXPORT GcsOptions {
 bool Equals(const GcsOptions& other) const;
};

// - TODO(ARROW-1231) - review this documentation before closing the bug.
/// \brief GCS-backed FileSystem implementation.
///
/// Some implementation notes:
/// - TODO(ARROW-1231) - review all the notes once completed.
/// - buckets are treated as top-level directories on a "root".
/// - GCS buckets are in a global namespace, only one bucket
/// named `foo` exists in Google Cloud.
/// - Creating new top-level directories is implemented by creating
/// a bucket, this may be a slower operation than usual.
/// - A principal (service account, user, etc) can only list the
/// buckets for a single project, but can access the buckets
/// for many projects. It is possible that listing "all"
/// the buckets returns fewer buckets than you have access to.
/// - GCS does not have directories, they are emulated in this
/// library by listing objects with a common prefix.
/// - In general, GCS has much higher latency than local filesystems.
/// The throughput of GCS is comparable to the throughput of
/// a local file system.
/// GCS (Google Cloud Storage - https://cloud.google.com/storage) is a scalable object
/// storage system for any amount of data. The main abstractions in GCS are buckets and
/// objects. A bucket is a namespace for objects, buckets can store any number of objects,
/// tens of millions and even billions is not uncommon. Each object contains a single
/// blob of data, up to 5TiB in size. Buckets are typically configured to keep a single
/// version of each object, but versioning can be enabled. Versioning is important because
/// objects are immutable, once created one cannot append data to the object or modify the
/// object data in any way.
///
/// GCS buckets are in a global namespace, if a Google Cloud customer creates a bucket
/// named `foo` no other customer can create a bucket with the same name. Note that a
/// principal (a user or service account) may only list the buckets they are entitled to,
/// and then only within a project. It is not possible to list "all" the buckets.
///
/// Within each bucket objects are in flat namespace. GCS does not have folders or
/// directories. However, following some conventions it is possible to emulate
/// directories. To this end, this class:
///
/// - All buckets are treated as directories at the "root"
/// - Creating a root directory results in a new bucket being created, this may be slower
/// than most GCS operations.
/// - Any object with a name ending with a slash (`/`) character is treated as a
/// directory.
/// - The class creates marker objects for a directory, using a trailing slash in the
/// marker names. For debugging purposes, the metadata of these marker objects indicate
/// that they are markers created by this class. The class does not rely on this
/// annotation.
/// - GCS can list all the objects with a given prefix, this is used to emulate listing
/// of directories.
/// - In object lists GCS can summarize all the objects with a common prefix as a single
/// entry, this is used to emulate non-recursive lists. Note that GCS list time is
/// proportional to the number of objects in the prefix. Listing recursively takes
/// almost the same time as non-recursive lists.
///
class ARROW_EXPORT GcsFileSystem : public FileSystem {
 public:
 ~GcsFileSystem() override = default;
Expand All@@ -75,6 +94,7 @@ class ARROW_EXPORT GcsFileSystem : public FileSystem {

 Status DeleteDirContents(const std::string& path) override;

 /// This is not implemented in GcsFileSystem, as it would be too dangerous.
 Status DeleteRootDirContents() override;

 Status DeleteFile(const std::string& path) override;
Expand Down
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