swarm
This commit is contained in:
marsal wang
@ -0,0 +1,461 @@
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// 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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#include <stddef.h>
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#include <stdint.h>
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#include <stdlib.h> // For abort.
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#include <memory>
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#include <string>
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#include "v8config.h" // NOLINT(build/include)
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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() = default;
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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() = default;
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virtual void Run(double deadline_in_seconds) = 0;
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};
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/**
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* A TaskRunner allows scheduling of tasks. The TaskRunner may still be used to
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* post tasks after the isolate gets destructed, but these tasks may not get
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* executed anymore. All tasks posted to a given TaskRunner will be invoked in
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* sequence. Tasks can be posted from any thread.
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*/
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class TaskRunner {
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public:
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/**
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* Schedules a task to be invoked by this TaskRunner. The TaskRunner
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* implementation takes ownership of |task|.
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*/
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virtual void PostTask(std::unique_ptr<Task> task) = 0;
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/**
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* Schedules a task to be invoked by this TaskRunner. The TaskRunner
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* implementation takes ownership of |task|. The |task| cannot be nested
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* within other task executions.
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*
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* Requires that |TaskRunner::NonNestableTasksEnabled()| is true.
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*/
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virtual void PostNonNestableTask(std::unique_ptr<Task> task) {}
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/**
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* Schedules a task to be invoked by this TaskRunner. The task is scheduled
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* after the given number of seconds |delay_in_seconds|. The TaskRunner
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* implementation takes ownership of |task|.
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*/
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virtual void PostDelayedTask(std::unique_ptr<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 by this TaskRunner. The task is scheduled
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* after the given number of seconds |delay_in_seconds|. The TaskRunner
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* implementation takes ownership of |task|. The |task| cannot be nested
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* within other task executions.
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*
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* Requires that |TaskRunner::NonNestableDelayedTasksEnabled()| is true.
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*/
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virtual void PostNonNestableDelayedTask(std::unique_ptr<Task> task,
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double delay_in_seconds) {}
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/**
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* Schedules an idle task to be invoked by this TaskRunner. The task is
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* scheduled when the embedder is idle. Requires that
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* |TaskRunner::IdleTasksEnabled()| is true. Idle tasks may be reordered
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* relative to other task types and may be starved for an arbitrarily long
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* time if no idle time is available. The TaskRunner implementation takes
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* ownership of |task|.
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*/
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virtual void PostIdleTask(std::unique_ptr<IdleTask> task) = 0;
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/**
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* Returns true if idle tasks are enabled for this TaskRunner.
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*/
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virtual bool IdleTasksEnabled() = 0;
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/**
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* Returns true if non-nestable tasks are enabled for this TaskRunner.
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*/
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virtual bool NonNestableTasksEnabled() const { return false; }
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/**
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* Returns true if non-nestable delayed tasks are enabled for this TaskRunner.
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*/
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virtual bool NonNestableDelayedTasksEnabled() const { return false; }
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TaskRunner() = default;
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virtual ~TaskRunner() = default;
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TaskRunner(const TaskRunner&) = delete;
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TaskRunner& operator=(const TaskRunner&) = delete;
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};
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/**
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* The interface represents complex arguments to trace events.
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*/
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class ConvertableToTraceFormat {
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public:
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virtual ~ConvertableToTraceFormat() = default;
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/**
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* Append the class info to the provided |out| string. The appended
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* data must be a valid JSON object. Strings must be properly quoted, and
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* escaped. There is no processing applied to the content after it is
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* appended.
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*/
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virtual void AppendAsTraceFormat(std::string* out) const = 0;
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};
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/**
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* V8 Tracing controller.
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*
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* Can be implemented by an embedder to record trace events from V8.
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*/
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class TracingController {
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public:
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virtual ~TracingController() = default;
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/**
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* Called by TRACE_EVENT* macros, don't call this directly.
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* The name parameter is a category group for example:
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* TRACE_EVENT0("v8,parse", "V8.Parse")
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* The pointer returned points to a value with zero or more of the bits
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* defined in CategoryGroupEnabledFlags.
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**/
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virtual const uint8_t* GetCategoryGroupEnabled(const char* name) {
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static uint8_t no = 0;
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return &no;
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}
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/**
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* Adds a trace event to the platform tracing system. These function calls are
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* usually the result of a TRACE_* macro from trace_event_common.h when
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* tracing and the category of the particular trace are enabled. It is not
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* advisable to call these functions on their own; they are really only meant
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* to be used by the trace macros. The returned handle can be used by
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* UpdateTraceEventDuration to update the duration of COMPLETE events.
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*/
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virtual uint64_t AddTraceEvent(
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char phase, const uint8_t* category_enabled_flag, const char* name,
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const char* scope, uint64_t id, uint64_t bind_id, int32_t num_args,
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const char** arg_names, const uint8_t* arg_types,
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const uint64_t* arg_values,
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std::unique_ptr<ConvertableToTraceFormat>* arg_convertables,
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unsigned int flags) {
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return 0;
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}
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virtual uint64_t AddTraceEventWithTimestamp(
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char phase, const uint8_t* category_enabled_flag, const char* name,
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const char* scope, uint64_t id, uint64_t bind_id, int32_t num_args,
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const char** arg_names, const uint8_t* arg_types,
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const uint64_t* arg_values,
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std::unique_ptr<ConvertableToTraceFormat>* arg_convertables,
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unsigned int flags, int64_t timestamp) {
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return 0;
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}
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/**
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* Sets the duration field of a COMPLETE trace event. It must be called with
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* the handle returned from AddTraceEvent().
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**/
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virtual void UpdateTraceEventDuration(const uint8_t* category_enabled_flag,
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const char* name, uint64_t handle) {}
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class TraceStateObserver {
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public:
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virtual ~TraceStateObserver() = default;
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virtual void OnTraceEnabled() = 0;
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virtual void OnTraceDisabled() = 0;
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};
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/** Adds tracing state change observer. */
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virtual void AddTraceStateObserver(TraceStateObserver*) {}
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/** Removes tracing state change observer. */
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virtual void RemoveTraceStateObserver(TraceStateObserver*) {}
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};
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/**
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* A V8 memory page allocator.
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*
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* Can be implemented by an embedder to manage large host OS allocations.
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*/
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class PageAllocator {
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public:
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virtual ~PageAllocator() = default;
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/**
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* Gets the page granularity for AllocatePages and FreePages. Addresses and
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* lengths for those calls should be multiples of AllocatePageSize().
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*/
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virtual size_t AllocatePageSize() = 0;
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/**
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* Gets the page granularity for SetPermissions and ReleasePages. Addresses
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* and lengths for those calls should be multiples of CommitPageSize().
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*/
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virtual size_t CommitPageSize() = 0;
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/**
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* Sets the random seed so that GetRandomMmapAddr() will generate repeatable
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* sequences of random mmap addresses.
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*/
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virtual void SetRandomMmapSeed(int64_t seed) = 0;
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/**
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* Returns a randomized address, suitable for memory allocation under ASLR.
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* The address will be aligned to AllocatePageSize.
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*/
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virtual void* GetRandomMmapAddr() = 0;
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/**
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* Memory permissions.
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*/
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enum Permission {
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kNoAccess,
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kRead,
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kReadWrite,
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// TODO(hpayer): Remove this flag. Memory should never be rwx.
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kReadWriteExecute,
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kReadExecute
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};
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/**
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* Allocates memory in range with the given alignment and permission.
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*/
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virtual void* AllocatePages(void* address, size_t length, size_t alignment,
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Permission permissions) = 0;
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/**
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* Frees memory in a range that was allocated by a call to AllocatePages.
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*/
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virtual bool FreePages(void* address, size_t length) = 0;
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/**
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* Releases memory in a range that was allocated by a call to AllocatePages.
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*/
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virtual bool ReleasePages(void* address, size_t length,
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size_t new_length) = 0;
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/**
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* Sets permissions on pages in an allocated range.
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*/
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virtual bool SetPermissions(void* address, size_t length,
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Permission permissions) = 0;
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/**
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* Frees memory in the given [address, address + size) range. address and size
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* should be operating system page-aligned. The next write to this
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* memory area brings the memory transparently back.
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*/
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virtual bool DiscardSystemPages(void* address, size_t size) { return true; }
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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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virtual ~Platform() = default;
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/**
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* Allows the embedder to manage memory page allocations.
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*/
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virtual PageAllocator* GetPageAllocator() {
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// TODO(bbudge) Make this abstract after all embedders implement this.
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return nullptr;
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}
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/**
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* Enables the embedder to respond in cases where V8 can't allocate large
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* blocks of memory. V8 retries the failed allocation once after calling this
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* method. On success, execution continues; otherwise V8 exits with a fatal
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* error.
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* Embedder overrides of this function must NOT call back into V8.
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*/
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virtual void OnCriticalMemoryPressure() {
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// TODO(bbudge) Remove this when embedders override the following method.
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// See crbug.com/634547.
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}
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/**
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* Enables the embedder to respond in cases where V8 can't allocate large
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* memory regions. The |length| parameter is the amount of memory needed.
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* Returns true if memory is now available. Returns false if no memory could
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* be made available. V8 will retry allocations until this method returns
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* false.
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*
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* Embedder overrides of this function must NOT call back into V8.
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*/
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virtual bool OnCriticalMemoryPressure(size_t length) { return false; }
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/**
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* Gets the number of worker threads used by
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* Call(BlockingTask)OnWorkerThread(). This can be used to estimate the number
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* of tasks a work package should be split into. A return value of 0 means
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* that there are no worker threads available. Note that a value of 0 won't
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* prohibit V8 from posting tasks using |CallOnWorkerThread|.
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*/
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virtual int NumberOfWorkerThreads() = 0;
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/**
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* Returns a TaskRunner which can be used to post a task on the foreground.
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* This function should only be called from a foreground thread.
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*/
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virtual std::shared_ptr<v8::TaskRunner> GetForegroundTaskRunner(
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Isolate* isolate) = 0;
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/**
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* Schedules a task to be invoked on a worker thread.
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*/
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virtual void CallOnWorkerThread(std::unique_ptr<Task> task) = 0;
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/**
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* Schedules a task that blocks the main thread to be invoked with
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* high-priority on a worker thread.
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*/
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virtual void CallBlockingTaskOnWorkerThread(std::unique_ptr<Task> task) {
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// Embedders may optionally override this to process these tasks in a high
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// priority pool.
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CallOnWorkerThread(std::move(task));
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}
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/**
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* Schedules a task to be invoked with low-priority on a worker thread.
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*/
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virtual void CallLowPriorityTaskOnWorkerThread(std::unique_ptr<Task> task) {
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// Embedders may optionally override this to process these tasks in a low
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// priority pool.
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CallOnWorkerThread(std::move(task));
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}
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/**
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* Schedules a task to be invoked on a worker thread after |delay_in_seconds|
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* expires.
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*/
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virtual void CallDelayedOnWorkerThread(std::unique_ptr<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|. 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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V8_DEPRECATE_SOON(
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"Use a taskrunner acquired by GetForegroundTaskRunner instead.",
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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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V8_DEPRECATE_SOON(
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"Use a taskrunner acquired by GetForegroundTaskRunner instead.",
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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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V8_DEPRECATE_SOON(
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"Use a taskrunner acquired by GetForegroundTaskRunner instead.",
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virtual void CallIdleOnForegroundThread(Isolate* isolate,
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IdleTask* task)) {
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// This must be overriden if |IdleTasksEnabled()|.
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abort();
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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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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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* Current wall-clock time in milliseconds since epoch.
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* This function is expected to return at least millisecond-precision values.
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*/
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virtual double CurrentClockTimeMillis() = 0;
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typedef void (*StackTracePrinter)();
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/**
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* Returns a function pointer that print a stack trace of the current stack
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* on invocation. Disables printing of the stack trace if nullptr.
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*/
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virtual StackTracePrinter GetStackTracePrinter() { return nullptr; }
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/**
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* Returns an instance of a v8::TracingController. This must be non-nullptr.
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*/
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virtual TracingController* GetTracingController() = 0;
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/**
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* Tells the embedder to generate and upload a crashdump during an unexpected
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* but non-critical scenario.
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*/
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virtual void DumpWithoutCrashing() {}
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/**
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* Lets the embedder to add crash keys.
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*/
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virtual void AddCrashKey(int id, const char* name, uintptr_t value) {
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// "noop" is a valid implementation if the embedder doesn't care to log
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// additional data for crashes.
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}
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protected:
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/**
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* Default implementation of current wall-clock time in milliseconds
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* since epoch. Useful for implementing |CurrentClockTimeMillis| if
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* nothing special needed.
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*/
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V8_EXPORT static double SystemClockTimeMillis();
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};
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} // namespace v8
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#endif // V8_V8_PLATFORM_H_
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||||
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