CSHARP-5712: withTransaction API retries too frequently

src/MongoDB.Driver/Authentication/ScramSha/ScramShaFirstSaslStep.cs

@@ -25,13 +25,13 @@ internal sealed class ScramShaFirstSaslStep : ISaslStep
         private readonly IScramShaAlgorithm _algorithm;
         private readonly ScramCache _cache;
         private readonly UsernamePasswordCredential _credential;
-        private readonly IRandomStringGenerator _randomStringGenerator;
+        private readonly IRandom _random;
 
-        public ScramShaFirstSaslStep(IScramShaAlgorithm algorithm, UsernamePasswordCredential credential, IRandomStringGenerator randomStringGenerator, ScramCache cache)
+        public ScramShaFirstSaslStep(IScramShaAlgorithm algorithm, UsernamePasswordCredential credential, IRandom random, ScramCache cache)
         {
             _algorithm = algorithm;
             _credential = credential;
-            _randomStringGenerator = randomStringGenerator;
+            _random = random;
             _cache = cache;
         }
 
@@ -63,7 +63,7 @@ private string GenerateRandomString()
         {
             const string legalCharacters = "!\"#$%&'()*+-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`abcdefghijklmnopqrstuvwxyz{|}~";
 
-            return _randomStringGenerator.Generate(20, legalCharacters);
+            return _random.GenerateString(20, legalCharacters);
         }
 
         private string PrepUsername(string username)

src/MongoDB.Driver/Authentication/ScramSha/ScramShaSaslMechanism.cs

@@ -26,25 +26,25 @@ internal sealed class ScramShaSaslMechanism : ISaslMechanism
         public const string ScramSha256MechanismName = "SCRAM-SHA-256";
 
         public static ScramShaSaslMechanism CreateScramSha1Mechanism(SaslContext context)
-            => CreateScramSha1Mechanism(context, DefaultRandomStringGenerator.Instance);
+            => CreateScramSha1Mechanism(context, DefaultRandom.Instance);
 
-        internal static ScramShaSaslMechanism CreateScramSha1Mechanism(SaslContext context, IRandomStringGenerator randomStringGenerator)
-            => Create(context, ScramSha1MechanismName, new ScramSha1Algorithm(), randomStringGenerator);
+        internal static ScramShaSaslMechanism CreateScramSha1Mechanism(SaslContext context, IRandom random)
+            => Create(context, ScramSha1MechanismName, new ScramSha1Algorithm(), random);
 
         public static ScramShaSaslMechanism CreateScramSha256Mechanism(SaslContext context)
-            => CreateScramSha256Mechanism(context, DefaultRandomStringGenerator.Instance);
+            => CreateScramSha256Mechanism(context, DefaultRandom.Instance);
 
-        internal static ScramShaSaslMechanism CreateScramSha256Mechanism(SaslContext context, IRandomStringGenerator randomStringGenerator)
-            => Create(context, ScramSha256MechanismName, new ScramSha256Algorithm(), randomStringGenerator);
+        internal static ScramShaSaslMechanism CreateScramSha256Mechanism(SaslContext context, IRandom random)
+            => Create(context, ScramSha256MechanismName, new ScramSha256Algorithm(), random);
 
         private static ScramShaSaslMechanism Create(
             SaslContext context,
             string mechanismName,
             IScramShaAlgorithm algorithm,
-            IRandomStringGenerator randomStringGenerator)
+            IRandom random)
         {
             Ensure.IsNotNull(context, nameof(context));
-            Ensure.IsNotNull(randomStringGenerator, nameof(randomStringGenerator));
+            Ensure.IsNotNull(random, nameof(random));
             if (context.Mechanism != mechanismName)
             {
                 throw new InvalidOperationException($"Unexpected authentication mechanism: {context.Mechanism}");
@@ -63,25 +63,25 @@ private static ScramShaSaslMechanism Create(
                 throw new NotSupportedException($"{mechanismName} auth mechanism require password.");
             }
 
-            return new ScramShaSaslMechanism(mechanismName, algorithm, credential, randomStringGenerator, new ScramCache());
+            return new ScramShaSaslMechanism(mechanismName, algorithm, credential, random, new ScramCache());
         }
 
         private readonly IScramShaAlgorithm _algorithm;
         private readonly ScramCache _cache;
         private readonly UsernamePasswordCredential _credential;
-        private readonly IRandomStringGenerator _randomStringGenerator;
+        private readonly IRandom _random;
 
         private ScramShaSaslMechanism(
             string mechanismName,
             IScramShaAlgorithm algorithm,
             UsernamePasswordCredential credential,
-            IRandomStringGenerator randomStringGenerator,
+            IRandom random,
             ScramCache cache)
         {
             Name = mechanismName;
             _algorithm = algorithm;
             _credential = credential;
-            _randomStringGenerator = randomStringGenerator;
+            _random = random;
             _cache = cache;
         }
 
@@ -99,7 +99,7 @@ public BsonDocument CustomizeSaslStartCommand(BsonDocument startCommand)
         }
 
         public ISaslStep Initialize(SaslConversation conversation, ConnectionDescription description)
-            => new ScramShaFirstSaslStep(_algorithm, _credential, _randomStringGenerator, _cache);
+            => new ScramShaFirstSaslStep(_algorithm, _credential, _random, _cache);
 
         public void OnReAuthenticationRequired()
         {

src/MongoDB.Driver/ClientSessionHandle.cs

@@ -34,6 +34,7 @@ internal sealed class ClientSessionHandle : IClientSessionHandle, IClientSession
         private readonly ICoreSessionHandle _coreSession;
         private bool _disposed;
         private readonly ClientSessionOptions _options;
+        private readonly IRandom _random;
         private IServerSession _serverSession;
 
         // constructors
@@ -44,16 +45,17 @@ internal sealed class ClientSessionHandle : IClientSessionHandle, IClientSession
         /// <param name="options">The options.</param>
         /// <param name="coreSession">The wrapped session.</param>
         public ClientSessionHandle(IMongoClient client, ClientSessionOptions options, ICoreSessionHandle coreSession)
-            : this(client, options, coreSession, SystemClock.Instance)
+            : this(client, options, coreSession, SystemClock.Instance, DefaultRandom.Instance)
         {
         }
 
-        internal ClientSessionHandle(IMongoClient client, ClientSessionOptions options, ICoreSessionHandle coreSession, IClock clock)
+        internal ClientSessionHandle(IMongoClient client, ClientSessionOptions options, ICoreSessionHandle coreSession, IClock clock, IRandom random)
         {
             _client = client;
             _options = options;
             _coreSession = coreSession;
             _clock = clock;
+            _random = random;
         }
 
         // public properties
@@ -166,15 +168,15 @@ public void StartTransaction(TransactionOptions transactionOptions = null)
         {
             Ensure.IsNotNull(callback, nameof(callback));
 
-            return TransactionExecutor.ExecuteWithRetries(this, callback, transactionOptions, _clock, cancellationToken);
+            return TransactionExecutor.ExecuteWithRetries(this, callback, transactionOptions, _clock, _random, cancellationToken);
         }
 
         /// <inheritdoc />
         public Task<TResult> WithTransactionAsync<TResult>(Func<IClientSessionHandle, CancellationToken, Task<TResult>> callbackAsync, TransactionOptions transactionOptions = null, CancellationToken cancellationToken = default(CancellationToken))
         {
             Ensure.IsNotNull(callbackAsync, nameof(callbackAsync));
 
-            return TransactionExecutor.ExecuteWithRetriesAsync(this, callbackAsync, transactionOptions, _clock, cancellationToken);
+            return TransactionExecutor.ExecuteWithRetriesAsync(this, callbackAsync, transactionOptions, _clock, _random, cancellationToken);
         }
 
         private TransactionOptions GetEffectiveTransactionOptions(TransactionOptions transactionOptions)

src/MongoDB.Driver/Core/Misc/DefaultRandom.cs

@@ -0,0 +1,71 @@
+/* Copyright 2010-present MongoDB Inc.
+*
+* Licensed 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.
+*/
+
+using System.Security.Cryptography;
+
+namespace MongoDB.Driver.Core.Misc;
+
+internal sealed class DefaultRandom : IRandom
+{
+    public static DefaultRandom Instance { get; } = new DefaultRandom();
+
+    public string GenerateString(int length, string legalCharacters)
+    {
+        Ensure.IsGreaterThanOrEqualToZero(length, nameof(length));
+        Ensure.IsNotNullOrEmpty(legalCharacters, nameof(legalCharacters));
+
+        if (length == 0)
+        {
+            return string.Empty;
+        }
+
+#if NET472
+        var randomData = new byte[length];
+        using (var rng = RandomNumberGenerator.Create())
+        {
+            rng.GetBytes(randomData);
+        }
+
+        var sb = new System.Text.StringBuilder(length);
+        for (var i = 0; i < length; i++)
+        {
+            sb.Append(GetResultChar(legalCharacters, randomData[i]));
+        }
+
+        return sb.ToString();
+#else
+        return string.Create(length, legalCharacters, (buffer, charset) =>
+        {
+            var randomData = buffer.Length < 1024 ? stackalloc byte[buffer.Length] : new byte[buffer.Length];
+            RandomNumberGenerator.Fill(randomData);
+            for (var i = 0; i < buffer.Length; i++)
+            {
+                buffer[i] = GetResultChar(charset, randomData[i]);
+            }
+        });
+#endif
+
+        static char GetResultChar(string charset, byte randomValue) => charset[randomValue % charset.Length];
+    }
+
+    public double NextDouble()
+    {
+#if NET6_0_OR_GREATER
+        return System.Random.Shared.NextDouble();
+#else
+        return ThreadStaticRandom.NextDouble();
+#endif
+    }
+}

src/MongoDB.Driver/Core/Misc/IRandomStringGenerator.cs → src/MongoDB.Driver/Core/Misc/IRandom.cs

@@ -1,4 +1,4 @@
-/* Copyright 2013-present MongoDB Inc.
+/* Copyright 2010-present MongoDB Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
@@ -13,10 +13,12 @@
 * limitations under the License.
 */
 
-namespace MongoDB.Driver.Core.Misc
+namespace MongoDB.Driver.Core.Misc;
+
+internal interface IRandom
 {
-    internal interface IRandomStringGenerator
-    {
-        string Generate(int length, string legalCharacters);
-    }
+    string GenerateString(int length, string legalCharacters);
+
+    double NextDouble();
 }
+

src/MongoDB.Driver/Core/Misc/ThreadStaticRandom.cs

@@ -1,4 +1,4 @@
-/* Copyright 2013-present MongoDB Inc.
+/* Copyright 2010-present MongoDB Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
@@ -26,13 +26,14 @@ internal static class ThreadStaticRandom
         // static methods
         public static int Next(int maxValue)
         {
-            var random = __threadStaticRandom;
-            if (random == null)
-            {
-                random = __threadStaticRandom = new Random();
-            }
+            __threadStaticRandom ??= new Random();
+            return __threadStaticRandom.Next(maxValue);
+        }
 
-            return random.Next(maxValue);
+        public static double NextDouble()
+        {
+            __threadStaticRandom ??= new Random();
+            return __threadStaticRandom.NextDouble();
         }
     }
 }

src/MongoDB.Driver/Core/Operations/RetryabilityHelper.cs

@@ -108,6 +108,18 @@ public static void AddRetryableWriteErrorLabelIfRequired(MongoException exceptio
             }
         }
 
+        public static int GetRetryDelayMs(IRandom random, int attempt, double backoffBase, int backoffInitial, int backoffMax)
+        {
+            Ensure.IsNotNull(random, nameof(random));
+            Ensure.IsGreaterThanZero(attempt, nameof(attempt));
+            Ensure.IsGreaterThanZero(backoffBase, nameof(backoffBase));
+            Ensure.IsGreaterThanZero(backoffInitial, nameof(backoffInitial));
+            Ensure.IsGreaterThan(backoffMax, backoffInitial, nameof(backoffMax));
+
+            var j = random.NextDouble();
+            return (int)(j * Math.Min(backoffMax, backoffInitial * Math.Pow(backoffBase, attempt - 1)));
+        }
+
         public static bool IsCommandRetryable(BsonDocument command)
         {
             return