Disk cache: Switch the disk cache to use the cache_thread.

Add an InFlightBackendIO class that handles posting of
cacheoperations back and forth between the IO thread and
the cachethread.

BUG=26730
TEST=unit tests

Review URL: http://codereview.chromium.org/2945002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@52185 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 73 insertions, 0 deletions

diff --git a/net/disk_cache/in_flight_io.cc b/net/disk_cache/in_flight_io.cc
new file mode 100644
index 0000000..24b0e9c
--- /dev/null
+++ b/net/disk_cache/in_flight_io.cc
@@ -0,0 +1,73 @@
+// Copyright (c) 2006-2010 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 "net/disk_cache/in_flight_io.h"
+
+#include "base/logging.h"
+
+namespace disk_cache {
+
+// Runs on the primary thread.
+void BackgroundIO::OnIOSignalled() {
+  if (controller_)
+    controller_->InvokeCallback(this, false);
+}
+
+void BackgroundIO::Cancel() {
+  DCHECK(controller_);
+  controller_ = NULL;
+}
+
+// Runs on the background thread.
+void BackgroundIO::NotifyController() {
+  controller_->OnIOComplete(this);
+}
+
+// ---------------------------------------------------------------------------
+
+void InFlightIO::WaitForPendingIO() {
+  while (!io_list_.empty()) {
+    // Block the current thread until all pending IO completes.
+    IOList::iterator it = io_list_.begin();
+    InvokeCallback(*it, true);
+  }
+}
+
+// Runs on a background thread.
+void InFlightIO::OnIOComplete(BackgroundIO* operation) {
+#ifndef NDEBUG
+  if (callback_thread_ == MessageLoop::current()) {
+    DCHECK(single_thread_ || !running_);
+    single_thread_ = true;
+  }
+  running_ = true;
+#endif
+
+  callback_thread_->PostTask(FROM_HERE,
+                             NewRunnableMethod(operation,
+                                               &BackgroundIO::OnIOSignalled));
+  operation->io_completed()->Signal();
+}
+
+// Runs on the primary thread.
+void InFlightIO::InvokeCallback(BackgroundIO* operation, bool cancel_task) {
+  operation->io_completed()->Wait();
+
+  if (cancel_task)
+    operation->Cancel();
+
+  // Make sure that we remove the operation from the list before invoking the
+  // callback (so that a subsequent cancel does not invoke the callback again).
+  DCHECK(io_list_.find(operation) != io_list_.end());
+  io_list_.erase(operation);
+  OnOperationComplete(operation, cancel_task);
+}
+
+// Runs on the primary thread.
+void InFlightIO::OnOperationPosted(BackgroundIO* operation) {
+  DCHECK(callback_thread_ == MessageLoop::current());
+  io_list_.insert(operation);
+}
+
+}  // namespace disk_cache