Initial commit of sync engine code to browser/sync....

chrome/browser/sync/notifier/base/signal_thread_task.h

+// Copyright (c) 2009 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.
+
+#ifndef CHROME_BROWSER_SYNC_NOTIFIER_BASE_SIGNAL_THREAD_TASK_H_
+#define CHROME_BROWSER_SYNC_NOTIFIER_BASE_SIGNAL_THREAD_TASK_H_
+
+#include "talk/base/common.h"
+#include "talk/base/signalthread.h"
+#include "talk/base/sigslot.h"
+#include "talk/base/task.h"
+
+namespace notifier {
+
+template<class T>
+class SignalThreadTask : public talk_base::Task,
+                         public sigslot::has_slots<> {
+ public:
+  // Takes ownership of signal_thread.
+  SignalThreadTask(talk_base::Task* task_parent, T** signal_thread)
+    : talk_base::Task(task_parent),
+      signal_thread_(NULL),
+      finished_(false) {
+    SetSignalThread(signal_thread);
+  }
+
+  virtual ~SignalThreadTask() {
+    ClearSignalThread();
+  }
+
+  virtual void Stop() {
+    Task::Stop();
+    ClearSignalThread();
+  }
+
+  virtual int ProcessStart() {
+    ASSERT(GetState() == talk_base::Task::STATE_START);
+    signal_thread_->SignalWorkDone.connect(
+        this,
+        &SignalThreadTask<T>::OnWorkDone);
+    signal_thread_->Start();
+    return talk_base::Task::STATE_RESPONSE;
+  }
+
+  int ProcessResponse() {
+    if (!finished_) {
+      return talk_base::Task::STATE_BLOCKED;
+    }
+    SignalWorkDone(signal_thread_);
+    ClearSignalThread();
+    return talk_base::Task::STATE_DONE;
+  }
+
+  sigslot::signal1<T*> SignalWorkDone;
+
+ private:
+  // Takes ownership of signal_thread
+  void SetSignalThread(T** signal_thread) {
+    ASSERT(!signal_thread_ && signal_thread && *signal_thread);
+    // Verify that no one is listening to the signal thread
+    // for work done.  They should be using this class instead.
+    ASSERT((*signal_thread)->SignalWorkDone.is_empty());
+
+    signal_thread_ = *signal_thread;
+
+    // Helps callers not to use signal thread after this point
+    // since this class has taken ownership (and avoid the
+    // error of doing signal_thread->Start()).
+    *signal_thread = NULL;
+  }
+
+  void OnWorkDone(talk_base::SignalThread* signal_thread) {
+    ASSERT(signal_thread == signal_thread_);
+    finished_ = true;
+    Wake();
+  }
+
+  void ClearSignalThread() {
+    if (signal_thread_) {
+      signal_thread_->Destroy();
+      signal_thread_ = NULL;
+    }
+  }
+
+  T* signal_thread_;
+  bool finished_;
+  DISALLOW_COPY_AND_ASSIGN(SignalThreadTask);
+};
+
+}  // namespace notifier
+
+#endif  // CHROME_BROWSER_SYNC_NOTIFIER_BASE_SIGNAL_THREAD_TASK_H_