PARQUET-400: Replace CompatibilityUtil with SeekableInputStream. #349
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| /* | ||
| * Licensed to the Apache Software Foundation (ASF) under one | ||
| * or more contributor license agreements. See the NOTICE file | ||
| * distributed with this work for additional information | ||
| * regarding copyright ownership. The ASF licenses this file | ||
| * to you under the Apache License, Version 2.0 (the | ||
| * "License"); you may not use this file except in compliance | ||
| * with the License. You may obtain a copy of the License at | ||
| * | ||
| * http://www.apache.org/licenses/LICENSE-2.0 | ||
| * | ||
| * Unless required by applicable law or agreed to in writing, | ||
| * software distributed under the License is distributed on an | ||
| * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY | ||
| * KIND, either express or implied. See the License for the | ||
| * specific language governing permissions and limitations | ||
| * under the License. | ||
| */ | ||
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| package org.apache.parquet.io; | ||
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| import java.io.EOFException; | ||
| import java.io.IOException; | ||
| import java.io.InputStream; | ||
| import java.nio.ByteBuffer; | ||
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| /** | ||
| * {@code SeekableInputStream} is an interface with the methods needed by | ||
| * Parquet to read data from a file or Hadoop data stream. | ||
| */ | ||
| public abstract class SeekableInputStream extends InputStream { | ||
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Member
There was a problem hiding this comment. Let's add getLength() as well.
Contributor
Author
There was a problem hiding this comment. A seekable stream is a fairly normal construct, while a stream that knows its own length is irregular. I think we are probably better off having a slightly higher-level concept of a stream provider that knows the length of streams it opens. That would basically encapsulate FileStatus and FileSystem so you can pass a single object that can open parallel streams for a single Parquet file. How about doing this as a follow up? This issue is a blocker for 1.9.0 so I'd like to get it in. We can discuss the right way to pass around the length but also work toward getting 1.9.0 out. I'll open an issue for this. |
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| /** | ||
| * Return the current position in the InputStream. | ||
| * | ||
| * @return current position in bytes from the start of the stream | ||
| * @throws IOException If the underlying stream throws IOException | ||
| */ | ||
| public abstract long getPos() throws IOException; | ||
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| /** | ||
| * Seek to a new position in the InputStream. | ||
| * | ||
| * @param newPos the new position to seek to | ||
| * @throws IOException If the underlying stream throws IOException | ||
| */ | ||
| public abstract void seek(long newPos) throws IOException; | ||
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| /** | ||
| * Read a byte array of data, from position 0 to the end of the array. | ||
| * <p> | ||
| * This method is equivalent to {@code read(bytes, 0, bytes.length)}. | ||
| * <p> | ||
| * This method will block until len bytes are available to copy into the | ||
| * array, or will throw {@link EOFException} if the stream ends before the | ||
| * array is full. | ||
| * | ||
| * @param bytes a byte array to fill with data from the stream | ||
| * @throws IOException If the underlying stream throws IOException | ||
| * @throws EOFException If the stream has fewer bytes left than are needed to | ||
| * fill the array, {@code bytes.length} | ||
| */ | ||
| public abstract void readFully(byte[] bytes) throws IOException; | ||
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There was a problem hiding this comment. lets document the contract of this method a bit - I did that here: https://github.com/apache/parquet-mr/pull/346/files#diff-8c94893b24edb4a7971eb0cbd167754aR41. We can either reuse that or tweak it..
Member
There was a problem hiding this comment. agreed. We should document this class.
Contributor
Author
There was a problem hiding this comment. Added javadoc for the whole class. |
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| /** | ||
| * Read {@code len} bytes of data into an array, at position {@code start}. | ||
| * <p> | ||
| * This method will block until len bytes are available to copy into the | ||
| * array, or will throw {@link EOFException} if the stream ends before the | ||
| * array is full. | ||
| * | ||
| * @param bytes a byte array to fill with data from the stream | ||
| * @throws IOException If the underlying stream throws IOException | ||
| * @throws EOFException If the stream has fewer than {@code len} bytes left | ||
| */ | ||
| public abstract void readFully(byte[] bytes, int start, int len) throws IOException; | ||
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| /** | ||
| * Read {@code buf.remaining()} bytes of data into a {@link ByteBuffer}. | ||
| * <p> | ||
| * This method will copy available bytes into the buffer, reading at most | ||
| * {@code buf.remaining()} bytes. The number of bytes actually copied is | ||
| * returned by the method, or -1 is returned to signal that the end of the | ||
| * underlying stream has been reached. | ||
| * | ||
| * @param buf a byte array to fill with data from the stream | ||
| * @return the number of bytes read or -1 if the stream ended | ||
| * @throws IOException If the underlying stream throws IOException | ||
| */ | ||
| public abstract int read(ByteBuffer buf) throws IOException; | ||
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| /** | ||
| * Read {@code buf.remaining()} bytes of data into a {@link ByteBuffer}. | ||
| * <p> | ||
| * This method will block until {@code buf.remaining()} bytes are available | ||
| * to copy into the buffer, or will throw {@link EOFException} if the stream | ||
| * ends before the buffer is full. | ||
| * | ||
| * @param buf a byte array to fill with data from the stream | ||
| * @throws IOException If the underlying stream throws IOException | ||
| * @throws EOFException If the stream has fewer bytes left than are needed to | ||
| * fill the buffer, {@code buf.remaining()} | ||
| */ | ||
| public abstract void readFully(ByteBuffer buf) throws IOException; | ||
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| } | ||
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Member
There was a problem hiding this comment. this is a great addition, this should please people who want more decoupling from hadoop as well. |
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Lets add some javadoc on this abstract class and its purpose etc.
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Wondering if SeekableInputStream is the right name? Maybe ParquetInputStream?
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This api is not really Parquet specific. It allows to seek and read blocks of the file.
Being in a parquet package is enough "parquet" in the name I think.