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