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external/v8/include/v8-platform.h

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+// Copyright 2013 the V8 project 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 V8_V8_PLATFORM_H_
+#define V8_V8_PLATFORM_H_
+
+namespace v8 {
+
+class Isolate;
+
+/**
+ * A Task represents a unit of work.
+ */
+class Task {
+ public:
+  virtual ~Task() {}
+
+  virtual void Run() = 0;
+};
+
+/**
+ * V8 Platform abstraction layer.
+ *
+ * The embedder has to provide an implementation of this interface before
+ * initializing the rest of V8.
+ */
+class Platform {
+ public:
+  /**
+   * This enum is used to indicate whether a task is potentially long running,
+   * or causes a long wait. The embedder might want to use this hint to decide
+   * whether to execute the task on a dedicated thread.
+   */
+  enum ExpectedRuntime {
+    kShortRunningTask,
+    kLongRunningTask
+  };
+
+  virtual ~Platform() {}
+
+  /**
+   * Schedules a task to be invoked on a background thread. |expected_runtime|
+   * indicates that the task will run a long time. The Platform implementation
+   * takes ownership of |task|. There is no guarantee about order of execution
+   * of tasks wrt order of scheduling, nor is there a guarantee about the
+   * thread the task will be run on.
+   */
+  virtual void CallOnBackgroundThread(Task* task,
+                                      ExpectedRuntime expected_runtime) = 0;
+
+  /**
+   * Schedules a task to be invoked on a foreground thread wrt a specific
+   * |isolate|. Tasks posted for the same isolate should be execute in order of
+   * scheduling. The definition of "foreground" is opaque to V8.
+   */
+  virtual void CallOnForegroundThread(Isolate* isolate, Task* task) = 0;
+
+  /**
+   * Monotonically increasing time in seconds from an arbitrary fixed point in
+   * the past. This function is expected to return at least
+   * millisecond-precision values. For this reason,
+   * it is recommended that the fixed point be no further in the past than
+   * the epoch.
+   **/
+  virtual double MonotonicallyIncreasingTime() = 0;
+};
+
+}  // namespace v8
+
+#endif  // V8_V8_PLATFORM_H_