IndexedDB: Ensure transactions without requests commit in the same order

content/browser/indexed_db/indexed_db_transaction.cc

 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/indexed_db/indexed_db_transaction.h"
 
 #include "base/bind.h"
 #include "base/location.h"
 #include "base/logging.h"
 #include "base/single_thread_task_runner.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "content/browser/indexed_db/indexed_db_backing_store.h"
 #include "content/browser/indexed_db/indexed_db_cursor.h"
 #include "content/browser/indexed_db/indexed_db_database.h"
 #include "content/browser/indexed_db/indexed_db_database_callbacks.h"
 #include "content/browser/indexed_db/indexed_db_tracing.h"
 #include "content/browser/indexed_db/indexed_db_transaction_coordinator.h"
 #include "third_party/WebKit/public/platform/modules/indexeddb/WebIDBDatabaseException.h"
 #include "third_party/leveldatabase/env_chromium.h"
 
 namespace content {
 
+namespace {
+
 const int64_t kInactivityTimeoutPeriodSeconds = 60;
 
+// Helper for posting a task to call IndexedDBTransaction::Commit when we know
+// the transaction had no requests and therefore the commit must succeed.
+void CommitUnused(scoped_refptr<IndexedDBTransaction> transaction) {
+  leveldb::Status status = transaction->Commit();
+  DCHECK(status.ok());
+}
+
+}  // namespace
+
 IndexedDBTransaction::TaskQueue::TaskQueue() {}
 IndexedDBTransaction::TaskQueue::~TaskQueue() { clear(); }
 
 void IndexedDBTransaction::TaskQueue::clear() {
   while (!queue_.empty())
     queue_.pop();
 }
 
 IndexedDBTransaction::Operation IndexedDBTransaction::TaskQueue::pop() {
   DCHECK(!queue_.empty());
@@ skipping 161 matching lines @@
 void IndexedDBTransaction::UnregisterOpenCursor(IndexedDBCursor* cursor) {
   open_cursors_.erase(cursor);
 }
 
 void IndexedDBTransaction::Start() {
   // TransactionCoordinator has started this transaction.
   DCHECK_EQ(CREATED, state_);
   state_ = STARTED;
   diagnostics_.start_time = base::Time::Now();
 
-  if (!used_)
+  if (!used_) {
+    if (commit_pending_) {
+      // The transaction has never had requests issued against it, but the
+      // front-end previously requested a commit; do the commit now, but not
+      // re-entrantly as that may renter the coordinator.
+      base::ThreadTaskRunnerHandle::Get()->PostTask(
+          FROM_HERE, base::Bind(&CommitUnused, make_scoped_refptr(this)));
+    }
     return;
+  }
 
   RunTasksIfStarted();
 }
 
 class BlobWriteCallbackImpl : public IndexedDBBackingStore::BlobWriteCallback {
  public:
   explicit BlobWriteCallbackImpl(
       scoped_refptr<IndexedDBTransaction> transaction)
       : transaction_(transaction) {}
   void Run(bool succeeded) override {
@@ skipping 27 matching lines @@
   // In multiprocess ports, front-end may have requested a commit but
   // an abort has already been initiated asynchronously by the
   // back-end.
   if (state_ == FINISHED)
     return leveldb::Status::OK();
   DCHECK_NE(state_, COMMITTING);
 
   DCHECK(!used_ || state_ == STARTED);
   commit_pending_ = true;
 
+  // Front-end has requested a commit, but this transaction is blocked by
+  // other transactions. The commit will be initiated when the transaction
+  // coordinator unblocks this transaction.
+  if (state_ != STARTED)
+    return leveldb::Status::OK();
+
   // Front-end has requested a commit, but there may be tasks like
   // create_index which are considered synchronous by the front-end
   // but are processed asynchronously.
   if (HasPendingTasks())
     return leveldb::Status::OK();
 
   state_ = COMMITTING;
 
   leveldb::Status s;
   if (!used_) {
@@ skipping 148 matching lines @@
 }
 
 void IndexedDBTransaction::CloseOpenCursors() {
   IDB_TRACE1("IndexedDBTransaction::CloseOpenCursors", "txn.id", id());
   for (auto* cursor : open_cursors_)
     cursor->Close();
   open_cursors_.clear();
 }
 
 }  // namespace content