From f5b0b9ceea456b019ae7d55f15f3496c3e270f2b Mon Sep 17 00:00:00 2001
From: Ben Turner <bent.mozilla@gmail.com>
Date: Tue, 2 Apr 2013 15:09:14 -0700
Subject: [PATCH] Bug 857283 - 'Smarter caching of index update queries'.
 r=khuey.

--HG--
extra : rebase_source : 489638cea833b32d05471188cf3a0b96947404cc
---
 dom/indexedDB/IDBObjectStore.cpp | 51 ++++++++++++++++++--------------
 1 file changed, 29 insertions(+), 22 deletions(-)

diff --git a/dom/indexedDB/IDBObjectStore.cpp b/dom/indexedDB/IDBObjectStore.cpp
index 9aca9b8dc516..9d753db74cc6 100644
--- a/dom/indexedDB/IDBObjectStore.cpp
+++ b/dom/indexedDB/IDBObjectStore.cpp
@@ -979,7 +979,6 @@ IDBObjectStore::UpdateIndexes(IDBTransaction* aTransaction,
                               int64_t aObjectDataId,
                               const nsTArray<IndexUpdateInfo>& aUpdateInfoArray)
 {
-  nsCOMPtr<mozIStorageStatement> stmt;
   nsresult rv;
 
   NS_ASSERTION(aObjectDataId != INT64_MIN, "Bad objectData id!");
@@ -987,41 +986,49 @@ IDBObjectStore::UpdateIndexes(IDBTransaction* aTransaction,
   NS_NAMED_LITERAL_CSTRING(objectDataId, "object_data_id");
 
   if (aOverwrite) {
-    stmt = aTransaction->GetCachedStatement(
-      "DELETE FROM unique_index_data "
-      "WHERE object_data_id = :object_data_id; "
-      "DELETE FROM index_data "
-      "WHERE object_data_id = :object_data_id");
-    NS_ENSURE_TRUE(stmt, NS_ERROR_FAILURE);
+    nsCOMPtr<mozIStorageStatement> deleteStmt =
+      aTransaction->GetCachedStatement(
+        "DELETE FROM unique_index_data "
+        "WHERE object_data_id = :object_data_id; "
+        "DELETE FROM index_data "
+        "WHERE object_data_id = :object_data_id");
+    NS_ENSURE_TRUE(deleteStmt, NS_ERROR_FAILURE);
 
-    mozStorageStatementScoper scoper(stmt);
+    mozStorageStatementScoper scoper(deleteStmt);
 
-    rv = stmt->BindInt64ByName(objectDataId, aObjectDataId);
+    rv = deleteStmt->BindInt64ByName(objectDataId, aObjectDataId);
     NS_ENSURE_SUCCESS(rv, rv);
 
-    rv = stmt->Execute();
+    rv = deleteStmt->Execute();
     NS_ENSURE_SUCCESS(rv, rv);
   }
 
+  // Avoid lots of hash lookups for objectStores with lots of indexes by lazily
+  // holding the necessary statements on the stack outside the loop.
+  nsCOMPtr<mozIStorageStatement> insertUniqueStmt;
+  nsCOMPtr<mozIStorageStatement> insertStmt;
+
   uint32_t infoCount = aUpdateInfoArray.Length();
   for (uint32_t i = 0; i < infoCount; i++) {
     const IndexUpdateInfo& updateInfo = aUpdateInfoArray[i];
 
-    // Insert new values.
-
-    stmt = updateInfo.indexUnique ?
-      aTransaction->GetCachedStatement(
-        "INSERT INTO unique_index_data "
-          "(index_id, object_data_id, object_data_key, value) "
-        "VALUES (:index_id, :object_data_id, :object_data_key, :value)") :
-      aTransaction->GetCachedStatement(
-        "INSERT OR IGNORE INTO index_data ("
-          "index_id, object_data_id, object_data_key, value) "
-        "VALUES (:index_id, :object_data_id, :object_data_key, :value)");
+    nsCOMPtr<mozIStorageStatement>& stmt =
+      updateInfo.indexUnique ? insertUniqueStmt : insertStmt;
 
+    if (!stmt) {
+      stmt = updateInfo.indexUnique ?
+        aTransaction->GetCachedStatement(
+          "INSERT INTO unique_index_data "
+            "(index_id, object_data_id, object_data_key, value) "
+          "VALUES (:index_id, :object_data_id, :object_data_key, :value)") :
+        aTransaction->GetCachedStatement(
+          "INSERT OR IGNORE INTO index_data ("
+            "index_id, object_data_id, object_data_key, value) "
+          "VALUES (:index_id, :object_data_id, :object_data_key, :value)");
+    }
     NS_ENSURE_TRUE(stmt, NS_ERROR_FAILURE);
 
-    mozStorageStatementScoper scoper4(stmt);
+    mozStorageStatementScoper scoper(stmt);
 
     rv = stmt->BindInt64ByName(NS_LITERAL_CSTRING("index_id"),
                                updateInfo.indexId);