[INTERNAL] SessionRetry: Adds support to yield immediately after the original attempt when READ_SESSION_NOT_AVAILABLE error is thrown

Microsoft.Azure.Cosmos/src/CosmosClientOptions.cs

@@ -753,6 +753,17 @@ public Func<HttpClient> HttpClientFactory
         /// </remarks>
         public AvailabilityStrategy AvailabilityStrategy { get; set; }
 
+        /// <summary>
+        /// Provides access to the maximum number of in-region retries for session retry policy.
+        /// If a value of less than or equal to 0 is provided we will not retry and yield after the original attempt, otherwise default is going to be 1
+        /// use value of less than or equal to for this parameter with care as this will have negative consequences for multi-master and some other scenerios.
+        /// </summary>
+        internal int MaxInRegionRetryCountForSessionRetry
+        {
+            get => this.SessionRetryOptions.MaxInRegionRetryCount;
+            set => this.SessionRetryOptions.MaxInRegionRetryCount = value;
+        }
+
         /// <summary>
         /// Provides SessionTokenMismatchRetryPolicy optimization through customer supplied region switch hints,
         /// which guide SDK-internal retry policies on how early to fallback to the next applicable region.

Microsoft.Azure.Cosmos/src/Fluent/CosmosClientBuilder.cs

@@ -583,6 +583,18 @@ public CosmosClientBuilder WithSerializerOptions(CosmosSerializationOptions cosm
             return this;
         }
 
+        /// <summary>
+        /// Sets the maximum number of in-region retries for session retry policy.
+        /// </summary>
+        /// <param name="maxInRegionRetryCount">The maximum number of retries within each region for read and write operations.
+        /// use value of less than or equal to 0 for this parameter with care as this will have negative consequences for multi-master and some other scenerios.</param>
+        /// <returns>The <see cref="CosmosClientBuilder"/> object</returns>
+        internal CosmosClientBuilder WithMaxInRegionRetryCountForSessionRetry(int maxInRegionRetryCount)
+        {
+            this.clientOptions.MaxInRegionRetryCountForSessionRetry = maxInRegionRetryCount;
+            return this;
+        }
+
         /// <summary>
         /// Provides SessionTokenMismatchRetryPolicy optimization through customer supplied region switch hints,
         /// which guide SDK-internal retry policies on how early to fallback to the next applicable region.

Microsoft.Azure.Cosmos/src/SessionRetryOptions.cs

@@ -26,12 +26,12 @@ public SessionRetryOptions()
         /// replication latency between the regions you chose
         /// </summary>
         public TimeSpan MinInRegionRetryTime { get; private set; }
-
+        
         /// <summary>
-        /// Sets the maximum number of retries within each region for read and write operations. The minimum value is 1 - the backoff time for the last in-region retry will ensure that the total retry time within the
+        /// Sets the maximum number of retries within each region for read and write operations - the backoff time for the last in-region retry will ensure that the total retry time within the
         /// region is at least the min. in-region retry time.
         /// </summary>
-        public int MaxInRegionRetryCount { get; private set; }
+        public int MaxInRegionRetryCount { get; internal set; }
 
         /// <summary>
         /// hints which guide SDK-internal retry policies on how early to switch retries to a different region. If true, will retry all replicas once and add a minimum delay before switching to the next region.If false, it will

Microsoft.Azure.Cosmos/src/Util/ConfigurationManager.cs

@@ -80,11 +80,10 @@ internal static class ConfigurationManager
         internal static readonly int MinMinInRegionRetryTimeForWritesInMs = 100;
 
         /// <summary>
-        /// intent is If a client specify a value, we will force it to be atleast 1, otherwise default is going to be 1(right now both the values are 1 but we have the provision to change them in future).
+        /// If a client specify a value  less than or equal to 0 we will not retry and yield after the original attempt, otherwise default is going to be 1
         /// </summary>
         internal static readonly string MaxRetriesInLocalRegionWhenRemoteRegionPreferred = "AZURE_COSMOS_MAX_RETRIES_IN_LOCAL_REGION_WHEN_REMOTE_REGION_PREFERRED";
         internal static readonly int DefaultMaxRetriesInLocalRegionWhenRemoteRegionPreferred = 1;
-        internal static readonly int MinMaxRetriesInLocalRegionWhenRemoteRegionPreferred = 1;
 
         /// <summary>
         /// A read-only string containing the environment variable name for enabling binary encoding. This will eventually
@@ -112,12 +111,10 @@ public static T GetEnvironmentVariable<T>(string variable, T defaultValue)
 
         public static int GetMaxRetriesInLocalRegionWhenRemoteRegionPreferred()
         {
-            return Math.Max(
-                ConfigurationManager
-                    .GetEnvironmentVariable(
-                        variable: MaxRetriesInLocalRegionWhenRemoteRegionPreferred,
-                        defaultValue: DefaultMaxRetriesInLocalRegionWhenRemoteRegionPreferred),
-                MinMaxRetriesInLocalRegionWhenRemoteRegionPreferred);
+            return ConfigurationManager
+                 .GetEnvironmentVariable(
+                     variable: MaxRetriesInLocalRegionWhenRemoteRegionPreferred,
+                     defaultValue: DefaultMaxRetriesInLocalRegionWhenRemoteRegionPreferred);
         }
 
         public static TimeSpan GetMinRetryTimeInLocalRegionWhenRemoteRegionPreferred()

Microsoft.Azure.Cosmos/tests/Microsoft.Azure.Cosmos.EmulatorTests/SessionRetryOptionsTest.cs

@@ -39,13 +39,15 @@ public async Task TestInitAsync()
         [DataRow(FaultInjectionOperationType.QueryItem, 1, true, DisplayName = "Validate Query Item operation with remote region preferred.")]
         [DataRow(FaultInjectionOperationType.ReadItem, 2, false, DisplayName = "Validate Read Item operation with local region preferred.")]
         [DataRow(FaultInjectionOperationType.QueryItem, 2, false, DisplayName = "Validate Query Item operation with local region preferred.")]
+        [DataRow(FaultInjectionOperationType.ReadItem, 0, true, DisplayName = "Validate Read Item operation with 0 sessionTokenMismatchRetryAttempts.")]
+        [DataRow(FaultInjectionOperationType.QueryItem, -1, true, DisplayName = "Validate Query Item operation with negative sessionTokenMismatchRetryAttempts.")]
         [TestCategory("MultiMaster")]
         public async Task ReadOperationWithReadSessionUnavailableTest(FaultInjectionOperationType faultInjectionOperationType,
             int sessionTokenMismatchRetryAttempts, Boolean remoteRegionPreferred)
         {
             string[] preferredRegions = this.writeRegionMap.Keys.ToArray();
             Environment.SetEnvironmentVariable(ConfigurationManager.MinInRegionRetryTimeForWritesInMs, "100");
-            Environment.SetEnvironmentVariable(ConfigurationManager.MaxRetriesInLocalRegionWhenRemoteRegionPreferred, Convert.ToString(sessionTokenMismatchRetryAttempts));
+
             try
             {
                 // if I go to first region for reading an item, I should get a 404/2002 response for 10 minutes
@@ -71,6 +73,7 @@ public async Task ReadOperationWithReadSessionUnavailableTest(FaultInjectionOper
                     ConsistencyLevel = ConsistencyLevel.Session,
                     ApplicationPreferredRegions = preferredRegions,
                     ConnectionMode = ConnectionMode.Direct,
+                    MaxInRegionRetryCountForSessionRetry = sessionTokenMismatchRetryAttempts
                 };
 
                 using (CosmosClient faultInjectionClient = new CosmosClient(
@@ -106,14 +109,14 @@ public async Task ReadOperationWithReadSessionUnavailableTest(FaultInjectionOper
 
                     if (remoteRegionPreferred)
                     {
-                        Assert.IsTrue(hitCount >= sessionTokenMismatchRetryAttempts && hitCount <= (1 + sessionTokenMismatchRetryAttempts) * 4);
+                        int effectiveRetryAttempts = Math.Max(sessionTokenMismatchRetryAttempts, 0);
+                        Assert.IsTrue(hitCount >= effectiveRetryAttempts && hitCount <= (1 + effectiveRetryAttempts) * 4);
                     }
                 }
             }
             finally
             {
                 Environment.SetEnvironmentVariable(ConfigurationManager.MinInRegionRetryTimeForWritesInMs, null);
-                Environment.SetEnvironmentVariable(ConfigurationManager.MaxRetriesInLocalRegionWhenRemoteRegionPreferred, null);
             }
         }
 
@@ -128,14 +131,15 @@ public async Task ReadOperationWithReadSessionUnavailableTest(FaultInjectionOper
         [DataRow(FaultInjectionOperationType.DeleteItem, 2, false, DisplayName = "Validate Delete Item operation with local region preferred.")]
         [DataRow(FaultInjectionOperationType.UpsertItem, 1, false, DisplayName = "Validate Upsert Item operation with local region preferred.")]
         [DataRow(FaultInjectionOperationType.PatchItem, 1, false, DisplayName = "Validate Patch Item operation with remote region preferred.")]
+        [DataRow(FaultInjectionOperationType.CreateItem, 0, true, DisplayName = "Validate Write Item operation with 0 sessionTokenMismatchRetryAttempts.")]
+        [DataRow(FaultInjectionOperationType.ReplaceItem, -1, true, DisplayName = "Validate Replace Item operation with negative sessionTokenMismatchRetryAttempts.")]
         [TestCategory("MultiMaster")]
         public async Task WriteOperationWithReadSessionUnavailableTest(FaultInjectionOperationType faultInjectionOperationType,
            int sessionTokenMismatchRetryAttempts, Boolean remoteRegionPreferred)
         {
 
             string[] preferredRegions = this.writeRegionMap.Keys.ToArray();
             Environment.SetEnvironmentVariable(ConfigurationManager.MinInRegionRetryTimeForWritesInMs, "100");
-            Environment.SetEnvironmentVariable(ConfigurationManager.MaxRetriesInLocalRegionWhenRemoteRegionPreferred, Convert.ToString(sessionTokenMismatchRetryAttempts));
 
             try
             {
@@ -161,6 +165,7 @@ public async Task WriteOperationWithReadSessionUnavailableTest(FaultInjectionOpe
                     ConsistencyLevel = ConsistencyLevel.Session,
                     ApplicationPreferredRegions = preferredRegions,
                     ConnectionMode = ConnectionMode.Direct,
+                    MaxInRegionRetryCountForSessionRetry = sessionTokenMismatchRetryAttempts
                 };
 
                 using (CosmosClient faultInjectionClient = new CosmosClient(
@@ -193,7 +198,9 @@ public async Task WriteOperationWithReadSessionUnavailableTest(FaultInjectionOpe
                     if (remoteRegionPreferred)
                     {
                         // higher hit count is possible while in MinRetryWaitTimeWithinRegion
-                        Assert.IsTrue(hitCount >= sessionTokenMismatchRetryAttempts);
+                        int effectiveRetryAttempts = Math.Max(sessionTokenMismatchRetryAttempts, 0);
+                        // higher hit count is possible while in MinRetryWaitTimeWithinRegion
+                        Assert.IsTrue(hitCount >= effectiveRetryAttempts);
                     }
                 }
             }

Microsoft.Azure.Cosmos/tests/Microsoft.Azure.Cosmos.Tests/SessionRetryOptionsUnitTests.cs

@@ -35,6 +35,20 @@ public void SessionRetryOptionsValidValuesTest()
             }
 
         }
+        [TestMethod]
+        public void CosmosClientOptions_SetMaxInRegionRetryCountForSessionRetry_AllowsNonPositiveValues()
+        {
+            CosmosClientOptions options = new CosmosClientOptions
+            {
+                // Set to zero
+                MaxInRegionRetryCountForSessionRetry = 0
+            };
+            Assert.AreEqual(0, options.SessionRetryOptions.MaxInRegionRetryCount, "Should allow setting MaxInRegionRetryCount to 0 via CosmosClientOptions");
+
+            // Set to negative
+            options.MaxInRegionRetryCountForSessionRetry = -10;
+            Assert.AreEqual(-10, options.SessionRetryOptions.MaxInRegionRetryCount, "Should allow setting MaxInRegionRetryCount to negative value via CosmosClientOptions");
+        }
 
         [TestMethod]
         public void SessionRetryOptionsDefaultValuesTest()