From d4e1ecc72c5ac47bbeb1f6e1447bb9486b8427fe Mon Sep 17 00:00:00 2001
From: Cyrus Najmabadi <cyrus.najmabadi@gmail.com>
Date: Tue, 28 Nov 2017 13:03:19 -0800
Subject: [PATCH] Avoid IEnumerable allocations when flusing data to sqlite.

---
 .../SQLite/SQLitePersistentStorage_WriteBatching.cs      | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/src/Workspaces/Core/Desktop/Workspace/SQLite/SQLitePersistentStorage_WriteBatching.cs b/src/Workspaces/Core/Desktop/Workspace/SQLite/SQLitePersistentStorage_WriteBatching.cs
index 0301a327e4855..5a09447b90a50 100644
--- a/src/Workspaces/Core/Desktop/Workspace/SQLite/SQLitePersistentStorage_WriteBatching.cs
+++ b/src/Workspaces/Core/Desktop/Workspace/SQLite/SQLitePersistentStorage_WriteBatching.cs
@@ -129,8 +129,13 @@ private async Task FlushSpecificWritesAsync<TKey>(
                 // performed by FlushAllPendingWritesAsync.
                 using (await _writeQueueGate.DisposableWaitAsync(cancellationToken).ConfigureAwait(false))
                 {
-                    // Get the writes we need to process.
-                    writesToProcess.AddRange(keyToWriteActions[key]);
+                    // Get the writes we need to process. 
+                    // Note: explicitly foreach so we operate on the struct enumerator for
+                    // MultiDictionary.ValueSet.
+                    foreach (var action in keyToWriteActions[key])
+                    {
+                        writesToProcess.Add(action);
+                    }
 
                     // and clear them from the queues so we don't process things multiple times.
                     keyToWriteActions.Remove(key);