IndexedDB: Don't timeout read-only transactions

Chrome introduced a transaction timeout to deal with potentially wedged
renderers (e.g. JS execution halted, etc) failing to complete transactions,
leaving the browser's transaction queue in a bad state. This was done
for all transactions, but since read-only transactions don't hold up
the queue it's safe to ignore them, which can reduce false-positives.

BUG=339229

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=254846

Review URL: https://codereview.chromium.org/180163010

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@255673 0039d316-1c4b-4281-b951-d872f2087c98

content/browser/indexed_db/indexed_db_transaction.cc

@@ -318,11 +318,14 @@ void IndexedDBTransaction::ProcessTaskQueue() {
     return;
 
   // Otherwise, start a timer in case the front-end gets wedged and
-  // never requests further activity.
-  timeout_timer_.Start(
-      FROM_HERE,
-      base::TimeDelta::FromSeconds(kInactivityTimeoutPeriodSeconds),
-      base::Bind(&IndexedDBTransaction::Timeout, this));
+  // never requests further activity. Read-only transactions don't
+  // block other transactions, so don't time those out.
+  if (mode_ != indexed_db::TRANSACTION_READ_ONLY) {
+    timeout_timer_.Start(
+        FROM_HERE,
+        base::TimeDelta::FromSeconds(kInactivityTimeoutPeriodSeconds),
+        base::Bind(&IndexedDBTransaction::Timeout, this));
+  }
 }
 
 void IndexedDBTransaction::Timeout() {

content/browser/indexed_db/indexed_db_transaction_unittest.cc

@@ -48,7 +48,7 @@ TEST_F(IndexedDBTransactionTest, Timeout) {
       id,
       new MockIndexedDBDatabaseCallbacks(),
       scope,
-      indexed_db::TRANSACTION_READ_ONLY,
+      indexed_db::TRANSACTION_READ_WRITE,
       db_,
       new IndexedDBFakeBackingStore::FakeTransaction(commit_success));
   db_->TransactionCreated(transaction);
@@ -77,6 +77,38 @@ TEST_F(IndexedDBTransactionTest, Timeout) {
   EXPECT_FALSE(transaction->IsTimeoutTimerRunning());
 }
 
+TEST_F(IndexedDBTransactionTest, NoTimeoutReadOnly) {
+  const int64 id = 0;
+  const std::set<int64> scope;
+  const bool commit_success = true;
+  scoped_refptr<IndexedDBTransaction> transaction = new IndexedDBTransaction(
+      id,
+      new MockIndexedDBDatabaseCallbacks(),
+      scope,
+      indexed_db::TRANSACTION_READ_ONLY,
+      db_,
+      new IndexedDBFakeBackingStore::FakeTransaction(commit_success));
+  db_->TransactionCreated(transaction);
+
+  // No conflicting transactions, so coordinator will start it immediately:
+  EXPECT_EQ(IndexedDBTransaction::STARTED, transaction->state());
+  EXPECT_FALSE(transaction->IsTimeoutTimerRunning());
+
+  // Schedule a task - timer won't be started until it's processed.
+  transaction->ScheduleTask(base::Bind(
+      &IndexedDBTransactionTest::DummyOperation, base::Unretained(this)));
+  EXPECT_FALSE(transaction->IsTimeoutTimerRunning());
+
+  // Transaction is read-only, so no need to time it out.
+  RunPostedTasks();
+  EXPECT_FALSE(transaction->IsTimeoutTimerRunning());
+
+  // Clean up to avoid leaks.
+  transaction->Abort();
+  EXPECT_EQ(IndexedDBTransaction::FINISHED, transaction->state());
+  EXPECT_FALSE(transaction->IsTimeoutTimerRunning());
+}
+
 class AbortObserver {
  public:
   AbortObserver() : abort_task_called_(false) {}