HttpClient: Adds optimization to avoid double buffering response (#1835)

* HttpClient: Adds optimization to avoid buffering response twice * Removed httpclient buffer setting.
Azure · Sep 11, 2020 · 8c31ca0 · 8c31ca0
1 parent ed0c8f0
commit 8c31ca0
Showing 1 changed file with 4 additions and 17 deletions.
diff --git a/Microsoft.Azure.Cosmos/src/HttpClient/CosmosHttpClientCore.cs b/Microsoft.Azure.Cosmos/src/HttpClient/CosmosHttpClientCore.cs
@@ -184,7 +184,6 @@ ValueTask<HttpRequestMessage> CreateRequestMessage()
 
             return this.SendHttpAsync(
                 CreateRequestMessage,
-                HttpCompletionOption.ResponseHeadersRead,
                 resourceType,
                 diagnosticsContext,
                 cancellationToken);
@@ -195,21 +194,6 @@ public override Task<HttpResponseMessage> SendHttpAsync(
             ResourceType resourceType,
             CosmosDiagnosticsContext diagnosticsContext,
             CancellationToken cancellationToken)
-        {
-            return this.SendHttpAsync(
-                createRequestMessageAsync,
-                HttpCompletionOption.ResponseContentRead,
-                resourceType,
-                diagnosticsContext,
-                cancellationToken);
-        }
-
-        private Task<HttpResponseMessage> SendHttpAsync(
-            Func<ValueTask<HttpRequestMessage>> createRequestMessageAsync,
-            HttpCompletionOption httpCompletionOption,
-            ResourceType resourceType,
-            CosmosDiagnosticsContext diagnosticsContext,
-            CancellationToken cancellationToken)
         {
             diagnosticsContext ??= new CosmosDiagnosticsContextCore();
             HttpRequestMessage requestMessage = null;
@@ -230,9 +214,12 @@ private Task<HttpResponseMessage> SendHttpAsync(
                             resourceType.ToResourceTypeString(),
                             requestMessage.Headers);
 
+                        // Only read the header initially. The content gets copied into a memory stream later
+                        // if we read the content http client will buffer the message and then it will get buffered
+                        // again when it is copied to the memory stream.
                         HttpResponseMessage responseMessage = await this.httpClient.SendAsync(
                                 requestMessage,
-                                httpCompletionOption,
+                                HttpCompletionOption.ResponseHeadersRead,
                                 cancellationToken);
 
                         DateTime receivedTimeUtc = DateTime.UtcNow;