Firestore TransactionOptions added, to specify maxAttempts (#318)

Author: dconeybe

docs/readme.md

@@ -158,6 +158,9 @@ Release Notes
 ### 9.2.0
 - Changes
     - Crashlytics: Fix requiring user code to reference Crashlytics when using il2cpp.
+    - Firestore: Added `TransactionOptions` to control how many times a
+      transaction will retry commits before failing
+      ([#318](https://github.com/firebase/firebase-unity-sdk/pull/318)).
 
 ### 9.1.0
 - Changes

firestore/CMakeLists.txt

@@ -78,6 +78,7 @@ set(firebase_firestore_src
   src/Source.cs
   src/Timestamp.cs
   src/Transaction.cs
+  src/TransactionOptions.cs
   src/TransactionManager.cs
   src/UnknownPropertyHandling.cs
   src/ValueDeserializer.cs

firestore/src/FirebaseFirestore.cs

@@ -248,10 +248,7 @@ public WriteBatch StartBatch() {
     /// be invoked on the main thread.</param>
     /// <returns>A task which completes when the transaction has committed.</returns>
     public Task RunTransactionAsync(Func<Transaction, Task> callback) {
-      Preconditions.CheckNotNull(callback, nameof(callback));
-      // Just pass through to the overload where the callback returns a Task<T>.
-      return RunTransactionAsync(transaction =>
-                                     Util.MapResult<object>(callback(transaction), null));
+      return RunTransactionAsync(new TransactionOptions(), callback);
     }
 
     /// <summary>
@@ -276,8 +273,65 @@ public Task RunTransactionAsync(Func<Transaction, Task> callback) {
     /// <returns>A task which completes when the transaction has committed. The result of the task
     /// then contains the result of the callback.</returns>
     public Task<T> RunTransactionAsync<T>(Func<Transaction, Task<T>> callback) {
+      return RunTransactionAsync(new TransactionOptions(), callback);
+    }
+
+    /// <summary>
+    /// Runs a transaction asynchronously, with an asynchronous callback that returns a value.
+    /// The specified callback is executed for a newly-created transaction.
+    /// </summary>
+    /// <remarks>
+    /// <para><c>RunTransactionAsync</c> executes the given callback on the main thread and then
+    /// attempts to commit the changes applied within the transaction. If any document read within
+    /// the transaction has changed, the <paramref name="callback"/> will be retried. If it fails to
+    /// commit after the maximum number of attempts specified in the given <c>TransactionOptions</c>
+    /// object, the transaction will fail.</para>
+    ///
+    /// <para>The maximum number of writes allowed in a single transaction is 500, but note that
+    /// each usage of <see cref="FieldValue.ServerTimestamp"/>, <c>FieldValue.ArrayUnion</c>,
+    /// <c>FieldValue.ArrayRemove</c>, or <c>FieldValue.Increment</c> inside a transaction counts as
+    /// an additional write.</para>
+    /// </remarks>
+    ///
+    /// <typeparam name="T">The result type of the callback.</typeparam>
+    /// <param name="options">The transaction options for controlling execution. Must not be
+    /// <c>null</c>.</param>
+    /// <param name="callback">The callback to execute. Must not be <c>null</c>. The callback will
+    /// be invoked on the main thread.</param>
+    /// <returns>A task which completes when the transaction has committed. The result of the task
+    /// then contains the result of the callback.</returns>
+    public Task<T> RunTransactionAsync<T>(TransactionOptions options, Func<Transaction, Task<T>> callback) {
+      Preconditions.CheckNotNull(options, nameof(options));
+      Preconditions.CheckNotNull(callback, nameof(callback));
+      return WithFirestoreProxy(proxy => _transactionManager.RunTransactionAsync(options, callback));
+    }
+
+    /// <summary>
+    /// Runs a transaction asynchronously, with an asynchronous callback that doesn't return a
+    /// value. The specified callback is executed for a newly-created transaction.
+    /// </summary>
+    /// <remarks>
+    /// <para><c>RunTransactionAsync</c> executes the given callback on the main thread and then
+    /// attempts to commit the changes applied within the transaction. If any document read within
+    /// the transaction has changed, the <paramref name="callback"/> will be retried. If it fails to
+    /// commit after the maximum number of attempts specified in the given <c>TransactionOptions</c>
+    /// object, the transaction will fail.</para>
+    ///
+    /// <para>The maximum number of writes allowed in a single transaction is 500, but note that
+    /// each usage of <see cref="FieldValue.ServerTimestamp"/>, <c>FieldValue.ArrayUnion</c>,
+    /// <c>FieldValue.ArrayRemove</c>, or <c>FieldValue.Increment</c> inside a transaction counts as
+    /// an additional write.</para>
+    /// </remarks>
+    /// <param name="options">The transaction options for controlling execution. Must not be
+    /// <c>null</c>.</param>
+    /// <param name="callback">The callback to execute. Must not be <c>null</c>. The callback will
+    /// be invoked on the main thread.</param>
+    /// <returns>A task which completes when the transaction has committed.</returns>
+    public Task RunTransactionAsync(TransactionOptions options, Func<Transaction, Task> callback) {
+      Preconditions.CheckNotNull(options, nameof(options));
       Preconditions.CheckNotNull(callback, nameof(callback));
-      return WithFirestoreProxy(proxy => _transactionManager.RunTransactionAsync(callback));
+      // Just pass through to the overload where the callback returns a Task<T>.
+      return RunTransactionAsync(options, transaction => Util.MapResult<object>(callback(transaction), null));
     }
 
     private static SnapshotsInSyncCallbackMap snapshotsInSyncCallbacks = new SnapshotsInSyncCallbackMap();

firestore/src/TransactionManager.cs

@@ -67,9 +67,11 @@ public void Dispose() {
     /// <summary>
     /// Runs a transaction.
     /// </summary>
+    /// <param name="options">The transaction options to use.</param>.
     /// <param name="callback">The callback to run.</param>.
     /// <returns>A task that completes when the transaction has completed.</returns>
-    internal Task<T> RunTransactionAsync<T>(Func<Transaction, Task<T>> callback) {
+    internal Task<T> RunTransactionAsync<T>(TransactionOptions options,
+        Func<Transaction, Task<T>> callback) {
       // Store the result of the most recent invocation of the user-supplied callback.
       bool callbackWrapperInvoked = false;
       Task<T> lastCallbackTask = null;
@@ -118,7 +120,7 @@ internal Task<T> RunTransactionAsync<T>(Func<Transaction, Task<T>> callback) {
         }
       };
 
-      return _transactionManagerProxy.RunTransactionAsync(callbackId, ExecuteCallback)
+      return _transactionManagerProxy.RunTransactionAsync(callbackId, options.Proxy, ExecuteCallback)
           .ContinueWith<T>(overallCallback);
     }
 

firestore/src/TransactionOptions.cs

@@ -0,0 +1,82 @@
+// Copyright 2022 Google LLC
+//
+// 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
+//
+//     https://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;
+using System.Threading;
+
+namespace Firebase.Firestore {
+
+/// <summary>
+/// Options to customize transaction behavior for
+/// <see cref="FirebaseFirestore.RunTransactionAsync"/>.
+/// </summary>
+public sealed class TransactionOptions {
+
+  // The lock that must be held during all accesses to _proxy.
+  private readonly ReaderWriterLock _proxyLock = new ReaderWriterLock();
+
+  // The underlying C++ TransactionOptions object.
+  private TransactionOptionsProxy _proxy = new TransactionOptionsProxy();
+
+  internal TransactionOptionsProxy Proxy {
+    get {
+      _proxyLock.AcquireReaderLock(Int32.MaxValue);
+      try {
+        return new TransactionOptionsProxy(_proxy);
+      } finally {
+        _proxyLock.ReleaseReaderLock();
+      }
+    }
+  }
+
+  /// <summary>
+  /// Creates the default <c>TransactionOptions</c>.
+  /// </summary>
+  public TransactionOptions() {
+  }
+
+  /// <summary>
+  /// The maximum number of attempts to commit, after which the transaction fails.
+  /// </summary>
+  ///
+  /// <remarks>
+  /// The default value is 5, and must be greater than zero.
+  /// </remarks>
+  public Int32 MaxAttempts {
+    get {
+      _proxyLock.AcquireReaderLock(Int32.MaxValue);
+      try {
+        return _proxy.max_attempts();
+      } finally {
+        _proxyLock.ReleaseReaderLock();
+      }
+    }
+    set {
+      _proxyLock.AcquireWriterLock(Int32.MaxValue);
+      try {
+        _proxy.set_max_attempts(value);
+      } finally {
+        _proxyLock.ReleaseWriterLock();
+      }
+    }
+  }
+
+  /// <inheritdoc />
+  public override string ToString() {
+    return nameof(TransactionOptions) + "{" + nameof(MaxAttempts) + "=" + MaxAttempts + "}";
+  }
+
+}
+
+}

firestore/src/swig/firestore.i

@@ -411,6 +411,13 @@ SWIG_CREATE_PROXY(firebase::firestore::LoadBundleTaskProgress);
 %rename("%s") firebase::firestore::LoadBundleTaskProgress::state;
 %include "firestore/src/include/firebase/firestore/load_bundle_task_progress.h"
 
+// Generate a C# wrapper for TransactionOptions.
+SWIG_CREATE_PROXY(firebase::firestore::TransactionOptions);
+%rename("%s") firebase::firestore::TransactionOptions::TransactionOptions;
+%rename("%s") firebase::firestore::TransactionOptions::max_attempts;
+%rename("%s") firebase::firestore::TransactionOptions::set_max_attempts;
+%include "firestore/src/include/firebase/firestore/transaction_options.h"
+
 // Generate a C# wrapper for Firestore. Comes last because it refers to multiple
 // other classes (e.g. `CollectionReference`).
 SWIG_CREATE_PROXY(firebase::firestore::Firestore);

firestore/src/swig/transaction_manager.cc

@@ -177,23 +177,25 @@ class TransactionManagerInternal
   }
 
   Future<void> RunTransaction(int32_t callback_id,
+                              TransactionOptions options,
                               TransactionCallbackFn callback_fn) {
     std::lock_guard<std::mutex> lock(mutex_);
     if (is_disposed_) {
       return {};
     }
 
     auto shared_this = shared_from_this();
-    return firestore_->RunTransaction([shared_this, callback_id, callback_fn](
-                                          Transaction& transaction,
-                                          std::string& error_message) {
-      if (shared_this->ExecuteCallback(callback_id, callback_fn, transaction)) {
-        return Error::kErrorOk;
-      } else {
-        // Return a non-retryable error code.
-        return Error::kErrorInvalidArgument;
+    return firestore_->RunTransaction(
+      options,
+      [shared_this, callback_id, callback_fn](Transaction& transaction, std::string& error_message) {
+        if (shared_this->ExecuteCallback(callback_id, callback_fn, transaction)) {
+          return Error::kErrorOk;
+        } else {
+          // Return a non-retryable error code.
+          return Error::kErrorInvalidArgument;
+        }
       }
-    });
+    );
   }
 
  private:
@@ -271,14 +273,15 @@ void TransactionManager::Dispose() {
 }
 
 Future<void> TransactionManager::RunTransaction(
-    int32_t callback_id, TransactionCallbackFn callback_fn) {
+    int32_t callback_id, TransactionOptions options,
+    TransactionCallbackFn callback_fn) {
   // Make a local copy of `internal_` since it could be reset asynchronously
   // by a call to `Dispose()`.
   std::shared_ptr<TransactionManagerInternal> internal_local = internal_;
   if (!internal_local) {
     return {};
   }
-  return internal_local->RunTransaction(callback_id, callback_fn);
+  return internal_local->RunTransaction(callback_id, options, callback_fn);
 }
 
 void TransactionCallback::OnCompletion(bool callback_successful) {

firestore/src/swig/transaction_manager.h

@@ -198,6 +198,7 @@ class TransactionManager {
   // If `Dispose()` has been invoked, or the `Firestore` instance has been
   // destroyed, then this method will immediately return an invalid `Future`.
   Future<void> RunTransaction(int32_t callback_id,
+                              TransactionOptions options,
                               TransactionCallbackFn callback);
 
  private:

firestore/testapp/Assets/Firebase/Sample/Firestore/InvalidArgumentsTest.cs

@@ -171,6 +171,14 @@ public static InvalidArgumentsTestCase[] TestCases {
             name = "FirebaseFirestore_RunTransactionAsync_WithTypeParameter_NullCallback",
             action = FirebaseFirestore_RunTransactionAsync_WithTypeParameter_NullCallback
           },
+          new InvalidArgumentsTestCase {
+            name = "FirebaseFirestore_RunTransactionAsync_WithoutTypeParameter_WithOptions_NullCallback",
+            action = FirebaseFirestore_RunTransactionAsync_WithoutTypeParameter_WithOptions_NullCallback
+          },
+          new InvalidArgumentsTestCase {
+            name = "FirebaseFirestore_RunTransactionAsync_WithTypeParameter_WithOptions_NullCallback",
+            action = FirebaseFirestore_RunTransactionAsync_WithTypeParameter_WithOptions_NullCallback
+          },
           new InvalidArgumentsTestCase { name = "FirebaseFirestoreSettings_Host_Null",
                                          action = FirebaseFirestoreSettings_Host_Null },
           new InvalidArgumentsTestCase { name = "FirebaseFirestoreSettings_Host_EmptyString",
@@ -693,6 +701,36 @@ private static void FirebaseFirestore_RunTransactionAsync_WithTypeParameter_Null
                               () => handler.db.RunTransactionAsync<object>(null));
     }
 
+    private static void FirebaseFirestore_RunTransactionAsync_WithoutTypeParameter_WithOptions_NullCallback(
+        UIHandlerAutomated handler) {
+      var options = new TransactionOptions();
+      handler.AssertException(typeof(ArgumentNullException),
+                              () => handler.db.RunTransactionAsync(options, null));
+    }
+
+    private static void FirebaseFirestore_RunTransactionAsync_WithTypeParameter_WithOptions_NullCallback(
+        UIHandlerAutomated handler) {
+      var options = new TransactionOptions();
+      handler.AssertException(typeof(ArgumentNullException),
+                              () => handler.db.RunTransactionAsync<object>(options, null));
+    }
+
+    private static void FirebaseFirestore_RunTransactionAsync_WithoutTypeParameter_WithOptions_NullOptions(
+        UIHandlerAutomated handler) {
+      DocumentReference doc = handler.TestDocument();
+      handler.AssertException(typeof(ArgumentNullException),
+          () => handler.db.RunTransactionAsync(null, tx => tx.GetSnapshotAsync(doc)));
+    }
+
+    private static void FirebaseFirestore_RunTransactionAsync_WithTypeParameter_WithOptions_NullOptions(
+        UIHandlerAutomated handler) {
+      DocumentReference doc = handler.TestDocument();
+      handler.AssertException(typeof(ArgumentNullException),
+          () => handler.db.RunTransactionAsync<object>(null, tx => tx.GetSnapshotAsync(doc)
+              .ContinueWith(snapshot => new object()))
+      );
+    }
+
     private static void FirebaseFirestoreSettings_Host_Null(UIHandlerAutomated handler) {
       FirebaseFirestoreSettings settings = handler.db.Settings;
       handler.AssertException(typeof(ArgumentNullException), () => settings.Host = null);