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114 lines
3.6 KiB
114 lines
3.6 KiB
// Copyright 2013 the V8 project authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#ifndef V8_V8_PLATFORM_H_
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#define V8_V8_PLATFORM_H_
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namespace v8 {
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class Isolate;
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/**
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* A Task represents a unit of work.
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*/
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class Task {
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public:
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virtual ~Task() {}
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virtual void Run() = 0;
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};
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/**
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* An IdleTask represents a unit of work to be performed in idle time.
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* The Run method is invoked with an argument that specifies the deadline in
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* seconds returned by MonotonicallyIncreasingTime().
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* The idle task is expected to complete by this deadline.
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*/
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class IdleTask {
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public:
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virtual ~IdleTask() {}
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virtual void Run(double deadline_in_seconds) = 0;
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};
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/**
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* V8 Platform abstraction layer.
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*
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* The embedder has to provide an implementation of this interface before
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* initializing the rest of V8.
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*/
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class Platform {
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public:
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/**
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* This enum is used to indicate whether a task is potentially long running,
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* or causes a long wait. The embedder might want to use this hint to decide
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* whether to execute the task on a dedicated thread.
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*/
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enum ExpectedRuntime {
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kShortRunningTask,
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kLongRunningTask
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};
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virtual ~Platform() {}
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/**
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* Schedules a task to be invoked on a background thread. |expected_runtime|
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* indicates that the task will run a long time. The Platform implementation
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* takes ownership of |task|. There is no guarantee about order of execution
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* of tasks wrt order of scheduling, nor is there a guarantee about the
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* thread the task will be run on.
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*/
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virtual void CallOnBackgroundThread(Task* task,
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ExpectedRuntime expected_runtime) = 0;
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/**
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* Schedules a task to be invoked on a foreground thread wrt a specific
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* |isolate|. Tasks posted for the same isolate should be execute in order of
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* scheduling. The definition of "foreground" is opaque to V8.
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*/
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virtual void CallOnForegroundThread(Isolate* isolate, Task* task) = 0;
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/**
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* Schedules a task to be invoked on a foreground thread wrt a specific
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* |isolate| after the given number of seconds |delay_in_seconds|.
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* Tasks posted for the same isolate should be execute in order of
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* scheduling. The definition of "foreground" is opaque to V8.
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*/
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virtual void CallDelayedOnForegroundThread(Isolate* isolate, Task* task,
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double delay_in_seconds) = 0;
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/**
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* Schedules a task to be invoked on a foreground thread wrt a specific
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* |isolate| when the embedder is idle.
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* Requires that SupportsIdleTasks(isolate) is true.
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* Idle tasks may be reordered relative to other task types and may be
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* starved for an arbitrarily long time if no idle time is available.
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* The definition of "foreground" is opaque to V8.
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*/
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virtual void CallIdleOnForegroundThread(Isolate* isolate, IdleTask* task) {
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// TODO(ulan): Make this function abstract after V8 roll in Chromium.
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}
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/**
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* Returns true if idle tasks are enabled for the given |isolate|.
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*/
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virtual bool IdleTasksEnabled(Isolate* isolate) {
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// TODO(ulan): Make this function abstract after V8 roll in Chromium.
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return false;
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}
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/**
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* Monotonically increasing time in seconds from an arbitrary fixed point in
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* the past. This function is expected to return at least
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* millisecond-precision values. For this reason,
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* it is recommended that the fixed point be no further in the past than
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* the epoch.
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**/
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virtual double MonotonicallyIncreasingTime() = 0;
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};
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} // namespace v8
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#endif // V8_V8_PLATFORM_H_
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