CSHARP-1378 BulkWrite enumerates requests argument multiple times

src/MongoDB.Driver/BulkWriteResult.cs

@@ -113,10 +113,10 @@ public abstract class BulkWriteResult<TDocument> : BulkWriteResult
         /// <param name="processedRequests">The processed requests.</param>
         protected BulkWriteResult(
             int requestCount,
-            IEnumerable<WriteModel<TDocument>> processedRequests)
+            List<WriteModel<TDocument>> processedRequests)
             : base(requestCount)
         {
-            _processedRequests = processedRequests.ToList();
+            _processedRequests = processedRequests;
         }
 
         // public properties
@@ -148,7 +148,7 @@ internal static BulkWriteResult<TDocument> FromCore(Core.Operations.BulkWriteOpe
                 result.ProcessedRequests.Select(r => WriteModel<TDocument>.FromCore(r)));
         }
 
-        internal static BulkWriteResult<TDocument> FromCore(Core.Operations.BulkWriteOperationResult result, IEnumerable<WriteModel<TDocument>> requests)
+        internal static BulkWriteResult<TDocument> FromCore(Core.Operations.BulkWriteOperationResult result, List<WriteModel<TDocument>> requests)
         {
             if (result.IsAcknowledged)
             {
@@ -202,6 +202,23 @@ public Acknowledged(
                 long? modifiedCount,
                 IEnumerable<WriteModel<TDocument>> processedRequests,
                 IEnumerable<BulkWriteUpsert> upserts)
+                : base(requestCount, processedRequests.ToList())
+            {
+                _matchedCount = matchedCount;
+                _deletedCount = deletedCount;
+                _insertedCount = insertedCount;
+                _modifiedCount = modifiedCount;
+                _upserts = upserts.ToList();
+            }
+
+            internal Acknowledged(
+                int requestCount,
+                long matchedCount,
+                long deletedCount,
+                long insertedCount,
+                long? modifiedCount,
+                List<WriteModel<TDocument>> processedRequests,
+                IEnumerable<BulkWriteUpsert> upserts)
                 : base(requestCount, processedRequests)
             {
                 _matchedCount = matchedCount;
@@ -279,6 +296,13 @@ public class Unacknowledged : BulkWriteResult<TDocument>
             public Unacknowledged(
                 int requestCount,
                 IEnumerable<WriteModel<TDocument>> processedRequests)
+                : base(requestCount, processedRequests.ToList())
+            {
+            }
+
+            internal Unacknowledged(
+                int requestCount,
+                List<WriteModel<TDocument>> processedRequests)
                 : base(requestCount, processedRequests)
             {
             }

src/MongoDB.Driver/MongoBulkWriteException.cs

@@ -223,7 +223,8 @@ internal static MongoBulkWriteException<TDocument> FromCore(MongoBulkWriteOperat
             var processedRequests = ex.Result.ProcessedRequests
                 .Select(r => new { CorrelationId = r.CorrelationId.Value, Request = requests[r.CorrelationId.Value] })
                 .OrderBy(x => x.CorrelationId)
-                .Select(x => x.Request);
+                .Select(x => x.Request)
+                .ToList();
 
             var unprocessedRequests = ex.UnprocessedRequests
                 .Select(r => new { CorrelationId = r.CorrelationId.Value, Request = requests[r.CorrelationId.Value] })

src/MongoDB.Driver/MongoCollectionImpl.cs

@@ -169,21 +169,24 @@ public override MongoCollectionSettings Settings
         {
             Ensure.IsNotNull(session, nameof(session));
             Ensure.IsNotNull(requests, nameof(requests));
-            if (!requests.Any())
+
+            var requestList = requests.ToList();
+
+            if (requestList.Count==0)
             {
                 throw new ArgumentException("Must contain at least 1 request.", "requests");
             }
             options = options ?? new BulkWriteOptions();
 
-            var operation = CreateBulkWriteOperation(requests, options);
+            var operation = CreateBulkWriteOperation(requestList, options);
             try
             {
                 var result = ExecuteWriteOperation(session, operation, cancellationToken);
-                return BulkWriteResult<TDocument>.FromCore(result, requests);
+                return BulkWriteResult<TDocument>.FromCore(result, requestList);
             }
             catch (MongoBulkWriteOperationException ex)
             {
-                throw MongoBulkWriteException<TDocument>.FromCore(ex, requests.ToList());
+                throw MongoBulkWriteException<TDocument>.FromCore(ex, requestList);
             }
         }
 
@@ -196,21 +199,24 @@ public override MongoCollectionSettings Settings
         {
             Ensure.IsNotNull(session, nameof(session));
             Ensure.IsNotNull(requests, nameof(requests));
-            if (!requests.Any())
+
+            var requestList = requests.ToList();
+
+            if (requestList.Count==0)
             {
                 throw new ArgumentException("Must contain at least 1 request.", "requests");
             }
             options = options ?? new BulkWriteOptions();
 
-            var operation = CreateBulkWriteOperation(requests, options);
+            var operation = CreateBulkWriteOperation(requestList, options);
             try
             {
                 var result = await ExecuteWriteOperationAsync(session, operation, cancellationToken).ConfigureAwait(false);
-                return BulkWriteResult<TDocument>.FromCore(result, requests);
+                return BulkWriteResult<TDocument>.FromCore(result, requestList);
             }
             catch (MongoBulkWriteOperationException ex)
             {
-                throw MongoBulkWriteException<TDocument>.FromCore(ex, requests.ToList());
+                throw MongoBulkWriteException<TDocument>.FromCore(ex, requestList);
             }
         }
 

tests/MongoDB.Driver.Tests/BulkWriteResultTests.cs

@@ -42,7 +42,7 @@ public void Should_convert_from_core_acknowledged_result_when_original_models_ex
                 processedRequests: new[] { new InsertRequest(new BsonDocument("b", 1)) },
                 upserts: new List<BulkWriteOperationUpsert>());
 
-            var models = new[] 
+            var models = new List<WriteModel<BsonDocument>>
             {
                 new InsertOneModel<BsonDocument>(new BsonDocument("a", 1))
             };
@@ -70,7 +70,7 @@ public void Should_convert_from_core_unacknowledged_result_when_original_models_
                 requestCount: 1,
                 processedRequests: new[] { new InsertRequest(new BsonDocument("b", 1)) });
 
-            var models = new[] 
+            var models = new List<WriteModel<BsonDocument>>
             {
                 new InsertOneModel<BsonDocument>(new BsonDocument("a", 1))
             };

tests/MongoDB.Driver.Tests/MongoCollectionImplTests.cs

@@ -398,6 +398,39 @@ public void BulkWrite_should_execute_a_BulkMixedWriteOperation(
             }
         }
 
+        [Theory]
+        [ParameterAttributeData]
+        public void BulkWrite_should_enum_once(
+            [Values(false, true)] bool async)
+        {
+            var subject = CreateSubject<BsonDocument>();
+            var options = new BulkWriteOptions
+            {
+                BypassDocumentValidation = false,
+                IsOrdered = false
+            };
+            var cancellationToken = new CancellationTokenSource().Token;
+            var operationResult = new BulkWriteOperationResult.Unacknowledged(9, new[] { new InsertRequest(new BsonDocument("b", 1)) });
+            _operationExecutor.EnqueueResult<BulkWriteOperationResult>(operationResult);
+            var count = 0;
+            var requests = Enumerable.Range(0,4).Select(n => {
+                    ++count;
+                    return new ReplaceOneModel<BsonDocument>(new BsonDocument("_id",n),new BsonDocument("_id",n));
+                });
+            BulkWriteResult<BsonDocument> result;
+            if (async)
+            {
+                result = subject.BulkWriteAsync(requests, options, cancellationToken).GetAwaiter().GetResult();
+            }
+            else
+            {
+                result = subject.BulkWrite(requests, options, cancellationToken);
+            }
+            var call = _operationExecutor.GetWriteCall<BulkWriteOperationResult>();
+            VerifySessionAndCancellationToken(call, null, cancellationToken);
+            count.Should().Be(4);
+        }
+
         [Theory]
         [ParameterAttributeData]
         public void Count_should_execute_a_CountOperation(