Implement Shuffle, GetString, and GetItems on Random{NumberGenerator}

[vcsjones]

Implements:

• Random.GetItems
• Random.Shuffle
• RandomNumberGenerator.GetString
• RandomNumberGenerator.GetHexString
• RandomNumberGenerator.Shuffle

This does both RandomNumberGenerator and Random in one go. If folks prefer I can split the PR.

Closes#73864.

[ghost]

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[ghost]

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Issue Details

---

Implements:

• Random.GetItems
• Random.Shuffle
• RandomNumberGenerator.GetString
• RandomNumberGenerator.GetHexString
• RandomNumberGenerator.Shuffle

This does both RandomNumberGenerator and Random in one go. If folks prefer I can split the PR.

Closes #73864.

Author:	vcsjones
Assignees:	vcsjones
Labels:	area-System.Security
Milestone:	-

[stephentoub]

Can you search around the repo and use these where it makes sense, e.g.

runtime/src/libraries/System.Text.RegularExpressions/src/System/Text/RegularExpressions/Symbolic/SymbolicRegexMatcher.Sample.cs

Line 179 in 6251d49

staticT[]Shuffle<T>(Randomrandom,T[]array)

runtime/src/libraries/Common/tests/System/RandomExtensions.cs

Line 10 in 57bfe47

publicstaticvoidShuffle<T>(thisRandomrandom,T[]array)

etc?

[stephentoub]

Use where possible

A quick search suggests other opportunities, e.g.

d:\repos\runtime\src\libraries\System.Net.Sockets\tests\FunctionalTests\UnixDomainSocketTest.cs(545):result = Path.Combine(Path.GetTempPath(), Path.GetRandomFileName() + new string('A', Random.Shared.Next(1, 32)));
d:\repos\runtime\src\libraries\System.Net.WebClient\tests\WebClientTest.cs(664):new string(Enumerable.Range(0, 512 * 1024).Select(_ => (char)('a' + Random.Shared.Next(0, 26))).ToArray());
d:\repos\runtime\src\libraries\Common\tests\System\Net\Http\PostScenarioTest.cs(151):var rand = new Random(42);
d:\repos\runtime\src\libraries\Common\tests\Tests\System\StringTests.cs(3776):Random rand = new Random(42);
d:\repos\runtime\src\libraries\Common\tests\Tests\System\StringTests.cs(3810):Random rand = new Random(42);
d:\repos\runtime\src\libraries\Common\tests\Tests\System\StringTests.cs(3832):Random rand = new Random(42);
d:\repos\runtime\src\libraries\Common\tests\TestUtilities\System\IO\FileCleanupTestBase.cs(178):Random random = new Random();
d:\repos\runtime\src\libraries\Common\tests\TestUtilities\System\IO\PathGenerator.cs(11):private static Random _rand = new Random();
d:\repos\runtime\src\libraries\Common\tests\TestUtilities\RandomTestCaseOrderer.cs(59):static List<T> Randomize(List<T> tests)
d:\repos\runtime\src\libraries\Common\tests\System\Net\Http\PostScenarioTest.cs(155):sb.Append((char)(rand.Next(0, 26) + 'a'));
d:\repos\runtime\src\libraries\Common\tests\TestUtilities\System\IO\FileCleanupTestBase.cs(181):sb.Append((char)('a' + random.Next(0, 26)));
d:\repos\runtime\src\libraries\System.IO\tests\StreamReader\StreamReaderTests.cs(407):data[i] = (char)('a' + r.Next(0, 26));
d:\repos\runtime\src\libraries\System.IO\tests\StreamReader\StreamReaderTests.cs(438):data[i] = (char)('a' + r.Next(0, 26));
d:\repos\runtime\src\libraries\System.IO\tests\StreamReader\StreamReaderTests.cs(469):data[i] = (char)('a' + r.Next(0, 26));
d:\repos\runtime\src\libraries\System.IO\tests\StreamReader\StreamReaderTests.cs(500):data[i] = (char)('a' + r.Next(0, 26));
d:\repos\runtime\src\libraries\System.IO\tests\StreamWriter\StreamWriter.WriteTests.cs(257):data[i] = (char)(rand.Next(0, 26) + 'a');
d:\repos\runtime\src\libraries\System.IO\tests\StreamWriter\StreamWriter.WriteTests.cs(290):data[i] = (char)(rand.Next(0, 26) + 'a');
d:\repos\runtime\src\libraries\System.IO\tests\StreamWriter\StreamWriter.WriteTests.cs(323):data[i] = (char)(rand.Next(0, 26) + 'a');
d:\repos\runtime\src\libraries\System.IO\tests\StreamWriter\StreamWriter.WriteTests.cs(356):data[i] = (char)(rand.Next(0, 26) + 'a');
d:\repos\runtime\src\libraries\System.Net.HttpListener\tests\HttpRequestStreamTests.cs(234):.Select(_ => (byte)('a' + rand.Next(0, 26)))
d:\repos\runtime\src\libraries\System.Net.HttpListener\tests\HttpRequestStreamTests.cs(274):.Select(_ => (byte)('a' + rand.Next(0, 26)))
d:\repos\runtime\src\libraries\System.Net.WebClient\tests\WebClientTest.cs(664):new string(Enumerable.Range(0, 512 * 1024).Select(_ => (char)('a' + Random.Shared.Next(0, 26))).ToArray());

[vcsjones]

A quick search suggests other opportunities, e.g.

I excluded searching in /tests/, but if we want to, that's fine. I'm generally risk-adverse touching tests purely for refactoring / using new APIs, but this seems simple enough.

[vcsjones]

A quick search suggests other opportunities, e.g.

I checked in a few more. Several of them I left unchanged because they have configurations that build for NetCoreAppMinimum or NetFramework. It didn't make sense to #ifdef in tests to me.

[vcsjones]

Sorry for the force push. I goofed on Co-authored-by and did not want to leave Michał out.

[stephentoub]

@vcsjones, when you get a chance, could you take a look at the pending comments/questions? Then we can get this merged. Thanks.

[bartonjs]

Similar to the N virtual calls concern in System.Random, it might be useful to change this to do something like

Span<byte>randomBytes=stackallocbyte[128];Span<int>randomIntStorage=stackallocint[randomBytes.Length/sizeof(int)];intrandomInts=0;for(inti=destination.Length-1;i>=0;i--){while(randomInts<=0){if(i<randomIntStorage.Length){randomBytes=randomBytes.Slice(0,i*sizeof(int));}Fill(randomBytes);randomInts=FilterInt32(randomBytes,randomIntStorage);}randomInts--;destination[i]=choices[randomInts[randomInts]];}

to reduce P/Invokes by a factor of randomIntStorage.Length.

Though that requires writing FilterInt32, and the complexity of above, so it should be checked to see if the perf justifies it.

(This is an idea for later, not a "right now")

[davidfowl]

Very nice APIs! I wonder if we should have T PickRandom(this IReadOnlyList<T> source)

[stephentoub]

Very nice APIs! I wonder if we should have T PickRandom(this IReadOnlyList source)

Concept seems reasonable, though to nit pick, to match the other APIs we'd probably want it to be called GetItem rather than PickRandom. Can you open a separate issue? Are there places it would be used in ASP.NET? I assume this is essentially shorthand for: source[RandomNumberGenerator.GetInt32(source.Count)]?

[davidfowl]

Can you open a separate issue?

I can.

Are there places it would be used in ASP.NET?

Not sure, I was building something with YARP when this came up.

Also would be used here

I assume this is essentially shorthand for: source[RandomNumberGenerator.GetInt32(source.Count)]?

Yep!

[davidfowl]

Filed an issue here