NCBC-932: BodyLength is zero when receive buffer tries read from it

Motivation
----------
Fixes a bug where the receive buffer length is the size of the last send.
In certain cases when the buffer is smaller than the header size, the
first receive will fail to read the entire document.

Modifications
-------------
Before the first receive is called in Connection.Send, the buffer is reset
back to the size specified in the config.

Results
-------
Documents that exceed the buffer length by less than 24 bytes will still
properly be inserted; ResponseStatus.None will not be returned.

Change-Id: I6b9f974cea267a5ba26ee48c94be81088aed79af
Reviewed-on: http://review.couchbase.org/52692
Reviewed-by: Simon Baslé <simon@couchbase.com>
Tested-by: Jeffry Morris <jeffrymorris@gmail.com>

Src/Couchbase.Tests/Core/Buckets/CouchbaseBucketTests.cs

@@ -1674,6 +1674,17 @@ public void When_Value_Is_Null_Get_Succeeds2()
             }
         }
 
+        [Test]
+        public void When_Document_Size_Exceeds_Buffer_Length_Upsert_Succeeds()
+        {
+            using (var bucket = _cluster.OpenBucket())
+            {
+                var json = File.ReadAllText(@"Data\\bigger-than-buffer-doc.json");
+                var result = bucket.Upsert("XyxyUserW4thPxrmiss1onInfa-10984", json);
+                Assert.AreEqual(ResponseStatus.Success, result.Status);
+            }
+        }
+
         [TestFixtureTearDown]
         public void TestFixtureTearDown()
         {

Src/Couchbase.Tests/Couchbase.Tests.csproj

@@ -268,6 +268,9 @@
     <None Include="Data\N1QL\prepared-statement.json">
       <CopyToOutputDirectory>Always</CopyToOutputDirectory>
     </None>
+    <None Include="Data\bigger-than-buffer-doc.json">
+      <CopyToOutputDirectory>Always</CopyToOutputDirectory>
+    </None>
     <None Include="packages.config" />
   </ItemGroup>
   <ItemGroup>

Src/Couchbase.Tests/CouchbaseBucket_Async_Tests.cs

@@ -835,5 +835,19 @@ public async void When_Expiration_Is_2_Decremented_Key_Expires_After_2_Seconds_A
                 }
             }
         }
+
+        [Test]
+        public async void When_Document_Size_Exceeds_Buffer_Length_Upsert_Succeeds()
+        {
+            using (var cluster = new Cluster())
+            {
+                using (var bucket = cluster.OpenBucket())
+                {
+                    var json = File.ReadAllText(@"Data\\bigger-than-buffer-doc.json");
+                    var result = await bucket.UpsertAsync("XyxyUserW4thPxrmiss1onInfa-10984_async", json);
+                    Assert.AreEqual(ResponseStatus.Success, result.Status);
+                }
+            }
+        }
     }
 }

Src/Couchbase/IO/Connection.cs

@@ -206,6 +206,7 @@ private void Send(Socket socket, SocketAsyncEventArgs e)
                 }
                 else
                 {
+                    e.SetBuffer(state.SendOffset, Configuration.BufferSize);
                     var willRaiseCompletedEvent = socket.ReceiveAsync(e);
                     if (!willRaiseCompletedEvent)
                     {