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454 lines
15 KiB
454 lines
15 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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#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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private: |
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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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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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