Line data Source code
1 : // Copyright 2013 the V8 project authors. All rights reserved.
2 : // Use of this source code is governed by a BSD-style license that can be
3 : // found in the LICENSE file.
4 :
5 : #ifndef V8_V8_PLATFORM_H_
6 : #define V8_V8_PLATFORM_H_
7 :
8 : #include <stddef.h>
9 : #include <stdint.h>
10 : #include <stdlib.h> // For abort.
11 : #include <memory>
12 : #include <string>
13 :
14 : #include "v8config.h" // NOLINT(build/include)
15 :
16 : namespace v8 {
17 :
18 : class Isolate;
19 :
20 : /**
21 : * A Task represents a unit of work.
22 : */
23 1932562 : class Task {
24 : public:
25 1930311 : virtual ~Task() = default;
26 :
27 : virtual void Run() = 0;
28 : };
29 :
30 : /**
31 : * An IdleTask represents a unit of work to be performed in idle time.
32 : * The Run method is invoked with an argument that specifies the deadline in
33 : * seconds returned by MonotonicallyIncreasingTime().
34 : * The idle task is expected to complete by this deadline.
35 : */
36 3755 : class IdleTask {
37 : public:
38 3753 : virtual ~IdleTask() = default;
39 : virtual void Run(double deadline_in_seconds) = 0;
40 : };
41 :
42 : /**
43 : * A TaskRunner allows scheduling of tasks. The TaskRunner may still be used to
44 : * post tasks after the isolate gets destructed, but these tasks may not get
45 : * executed anymore. All tasks posted to a given TaskRunner will be invoked in
46 : * sequence. Tasks can be posted from any thread.
47 : */
48 : class TaskRunner {
49 : public:
50 : /**
51 : * Schedules a task to be invoked by this TaskRunner. The TaskRunner
52 : * implementation takes ownership of |task|.
53 : */
54 : virtual void PostTask(std::unique_ptr<Task> task) = 0;
55 :
56 : /**
57 : * Schedules a task to be invoked by this TaskRunner. The TaskRunner
58 : * implementation takes ownership of |task|. The |task| cannot be nested
59 : * within other task executions.
60 : *
61 : * Requires that |TaskRunner::NonNestableTasksEnabled()| is true.
62 : */
63 0 : virtual void PostNonNestableTask(std::unique_ptr<Task> task) {}
64 :
65 : /**
66 : * Schedules a task to be invoked by this TaskRunner. The task is scheduled
67 : * after the given number of seconds |delay_in_seconds|. The TaskRunner
68 : * implementation takes ownership of |task|.
69 : */
70 : virtual void PostDelayedTask(std::unique_ptr<Task> task,
71 : double delay_in_seconds) = 0;
72 :
73 : /**
74 : * Schedules a task to be invoked by this TaskRunner. The task is scheduled
75 : * after the given number of seconds |delay_in_seconds|. The TaskRunner
76 : * implementation takes ownership of |task|. The |task| cannot be nested
77 : * within other task executions.
78 : *
79 : * Requires that |TaskRunner::NonNestableDelayedTasksEnabled()| is true.
80 : */
81 0 : virtual void PostNonNestableDelayedTask(std::unique_ptr<Task> task,
82 0 : double delay_in_seconds) {}
83 :
84 : /**
85 : * Schedules an idle task to be invoked by this TaskRunner. The task is
86 : * scheduled when the embedder is idle. Requires that
87 : * |TaskRunner::IdleTasksEnabled()| is true. Idle tasks may be reordered
88 : * relative to other task types and may be starved for an arbitrarily long
89 : * time if no idle time is available. The TaskRunner implementation takes
90 : * ownership of |task|.
91 : */
92 : virtual void PostIdleTask(std::unique_ptr<IdleTask> task) = 0;
93 :
94 : /**
95 : * Returns true if idle tasks are enabled for this TaskRunner.
96 : */
97 : virtual bool IdleTasksEnabled() = 0;
98 :
99 : /**
100 : * Returns true if non-nestable tasks are enabled for this TaskRunner.
101 : */
102 28197 : virtual bool NonNestableTasksEnabled() const { return false; }
103 :
104 : /**
105 : * Returns true if non-nestable delayed tasks are enabled for this TaskRunner.
106 : */
107 5326 : virtual bool NonNestableDelayedTasksEnabled() const { return false; }
108 :
109 122814 : TaskRunner() = default;
110 118444 : virtual ~TaskRunner() = default;
111 :
112 : private:
113 : TaskRunner(const TaskRunner&) = delete;
114 : TaskRunner& operator=(const TaskRunner&) = delete;
115 : };
116 :
117 : /**
118 : * The interface represents complex arguments to trace events.
119 : */
120 3449 : class ConvertableToTraceFormat {
121 : public:
122 3449 : virtual ~ConvertableToTraceFormat() = default;
123 :
124 : /**
125 : * Append the class info to the provided |out| string. The appended
126 : * data must be a valid JSON object. Strings must be properly quoted, and
127 : * escaped. There is no processing applied to the content after it is
128 : * appended.
129 : */
130 : virtual void AppendAsTraceFormat(std::string* out) const = 0;
131 : };
132 :
133 : /**
134 : * V8 Tracing controller.
135 : *
136 : * Can be implemented by an embedder to record trace events from V8.
137 : */
138 61129 : class TracingController {
139 : public:
140 58041 : virtual ~TracingController() = default;
141 :
142 : /**
143 : * Called by TRACE_EVENT* macros, don't call this directly.
144 : * The name parameter is a category group for example:
145 : * TRACE_EVENT0("v8,parse", "V8.Parse")
146 : * The pointer returned points to a value with zero or more of the bits
147 : * defined in CategoryGroupEnabledFlags.
148 : **/
149 0 : virtual const uint8_t* GetCategoryGroupEnabled(const char* name) {
150 : static uint8_t no = 0;
151 0 : return &no;
152 : }
153 :
154 : /**
155 : * Adds a trace event to the platform tracing system. These function calls are
156 : * usually the result of a TRACE_* macro from trace_event_common.h when
157 : * tracing and the category of the particular trace are enabled. It is not
158 : * advisable to call these functions on their own; they are really only meant
159 : * to be used by the trace macros. The returned handle can be used by
160 : * UpdateTraceEventDuration to update the duration of COMPLETE events.
161 : */
162 0 : virtual uint64_t AddTraceEvent(
163 : char phase, const uint8_t* category_enabled_flag, const char* name,
164 : const char* scope, uint64_t id, uint64_t bind_id, int32_t num_args,
165 : const char** arg_names, const uint8_t* arg_types,
166 : const uint64_t* arg_values,
167 : std::unique_ptr<ConvertableToTraceFormat>* arg_convertables,
168 : unsigned int flags) {
169 0 : return 0;
170 : }
171 0 : virtual uint64_t AddTraceEventWithTimestamp(
172 : char phase, const uint8_t* category_enabled_flag, const char* name,
173 : const char* scope, uint64_t id, uint64_t bind_id, int32_t num_args,
174 : const char** arg_names, const uint8_t* arg_types,
175 : const uint64_t* arg_values,
176 : std::unique_ptr<ConvertableToTraceFormat>* arg_convertables,
177 : unsigned int flags, int64_t timestamp) {
178 0 : return 0;
179 : }
180 :
181 : /**
182 : * Sets the duration field of a COMPLETE trace event. It must be called with
183 : * the handle returned from AddTraceEvent().
184 : **/
185 0 : virtual void UpdateTraceEventDuration(const uint8_t* category_enabled_flag,
186 0 : const char* name, uint64_t handle) {}
187 :
188 123450 : class TraceStateObserver {
189 : public:
190 122296 : virtual ~TraceStateObserver() = default;
191 : virtual void OnTraceEnabled() = 0;
192 : virtual void OnTraceDisabled() = 0;
193 : };
194 :
195 : /** Adds tracing state change observer. */
196 0 : virtual void AddTraceStateObserver(TraceStateObserver*) {}
197 :
198 : /** Removes tracing state change observer. */
199 0 : virtual void RemoveTraceStateObserver(TraceStateObserver*) {}
200 : };
201 :
202 : /**
203 : * A V8 memory page allocator.
204 : *
205 : * Can be implemented by an embedder to manage large host OS allocations.
206 : */
207 125009 : class PageAllocator {
208 : public:
209 121906 : virtual ~PageAllocator() = default;
210 :
211 : /**
212 : * Gets the page granularity for AllocatePages and FreePages. Addresses and
213 : * lengths for those calls should be multiples of AllocatePageSize().
214 : */
215 : virtual size_t AllocatePageSize() = 0;
216 :
217 : /**
218 : * Gets the page granularity for SetPermissions and ReleasePages. Addresses
219 : * and lengths for those calls should be multiples of CommitPageSize().
220 : */
221 : virtual size_t CommitPageSize() = 0;
222 :
223 : /**
224 : * Sets the random seed so that GetRandomMmapAddr() will generate repeatable
225 : * sequences of random mmap addresses.
226 : */
227 : virtual void SetRandomMmapSeed(int64_t seed) = 0;
228 :
229 : /**
230 : * Returns a randomized address, suitable for memory allocation under ASLR.
231 : * The address will be aligned to AllocatePageSize.
232 : */
233 : virtual void* GetRandomMmapAddr() = 0;
234 :
235 : /**
236 : * Memory permissions.
237 : */
238 : enum Permission {
239 : kNoAccess,
240 : kRead,
241 : kReadWrite,
242 : // TODO(hpayer): Remove this flag. Memory should never be rwx.
243 : kReadWriteExecute,
244 : kReadExecute
245 : };
246 :
247 : /**
248 : * Allocates memory in range with the given alignment and permission.
249 : */
250 : virtual void* AllocatePages(void* address, size_t length, size_t alignment,
251 : Permission permissions) = 0;
252 :
253 : /**
254 : * Frees memory in a range that was allocated by a call to AllocatePages.
255 : */
256 : virtual bool FreePages(void* address, size_t length) = 0;
257 :
258 : /**
259 : * Releases memory in a range that was allocated by a call to AllocatePages.
260 : */
261 : virtual bool ReleasePages(void* address, size_t length,
262 : size_t new_length) = 0;
263 :
264 : /**
265 : * Sets permissions on pages in an allocated range.
266 : */
267 : virtual bool SetPermissions(void* address, size_t length,
268 : Permission permissions) = 0;
269 :
270 : /**
271 : * Frees memory in the given [address, address + size) range. address and size
272 : * should be operating system page-aligned. The next write to this
273 : * memory area brings the memory transparently back.
274 : */
275 0 : virtual bool DiscardSystemPages(void* address, size_t size) { return true; }
276 : };
277 :
278 : /**
279 : * V8 Platform abstraction layer.
280 : *
281 : * The embedder has to provide an implementation of this interface before
282 : * initializing the rest of V8.
283 : */
284 61306 : class Platform {
285 : public:
286 58203 : virtual ~Platform() = default;
287 :
288 : /**
289 : * Allows the embedder to manage memory page allocations.
290 : */
291 0 : virtual PageAllocator* GetPageAllocator() {
292 : // TODO(bbudge) Make this abstract after all embedders implement this.
293 0 : return nullptr;
294 : }
295 :
296 : /**
297 : * Enables the embedder to respond in cases where V8 can't allocate large
298 : * blocks of memory. V8 retries the failed allocation once after calling this
299 : * method. On success, execution continues; otherwise V8 exits with a fatal
300 : * error.
301 : * Embedder overrides of this function must NOT call back into V8.
302 : */
303 0 : virtual void OnCriticalMemoryPressure() {
304 : // TODO(bbudge) Remove this when embedders override the following method.
305 : // See crbug.com/634547.
306 0 : }
307 :
308 : /**
309 : * Enables the embedder to respond in cases where V8 can't allocate large
310 : * memory regions. The |length| parameter is the amount of memory needed.
311 : * Returns true if memory is now available. Returns false if no memory could
312 : * be made available. V8 will retry allocations until this method returns
313 : * false.
314 : *
315 : * Embedder overrides of this function must NOT call back into V8.
316 : */
317 0 : virtual bool OnCriticalMemoryPressure(size_t length) { return false; }
318 :
319 : /**
320 : * Gets the number of worker threads used by
321 : * Call(BlockingTask)OnWorkerThread(). This can be used to estimate the number
322 : * of tasks a work package should be split into. A return value of 0 means
323 : * that there are no worker threads available. Note that a value of 0 won't
324 : * prohibit V8 from posting tasks using |CallOnWorkerThread|.
325 : */
326 : virtual int NumberOfWorkerThreads() = 0;
327 :
328 : /**
329 : * Returns a TaskRunner which can be used to post a task on the foreground.
330 : * This function should only be called from a foreground thread.
331 : */
332 : virtual std::shared_ptr<v8::TaskRunner> GetForegroundTaskRunner(
333 : Isolate* isolate) = 0;
334 :
335 : /**
336 : * Schedules a task to be invoked on a worker thread.
337 : */
338 : virtual void CallOnWorkerThread(std::unique_ptr<Task> task) = 0;
339 :
340 : /**
341 : * Schedules a task that blocks the main thread to be invoked with
342 : * high-priority on a worker thread.
343 : */
344 297001 : virtual void CallBlockingTaskOnWorkerThread(std::unique_ptr<Task> task) {
345 : // Embedders may optionally override this to process these tasks in a high
346 : // priority pool.
347 891003 : CallOnWorkerThread(std::move(task));
348 297001 : }
349 :
350 : /**
351 : * Schedules a task to be invoked with low-priority on a worker thread.
352 : */
353 10224 : virtual void CallLowPriorityTaskOnWorkerThread(std::unique_ptr<Task> task) {
354 : // Embedders may optionally override this to process these tasks in a low
355 : // priority pool.
356 30672 : CallOnWorkerThread(std::move(task));
357 10224 : }
358 :
359 : /**
360 : * Schedules a task to be invoked on a worker thread after |delay_in_seconds|
361 : * expires.
362 : */
363 : virtual void CallDelayedOnWorkerThread(std::unique_ptr<Task> task,
364 : double delay_in_seconds) = 0;
365 :
366 : /**
367 : * Schedules a task to be invoked on a foreground thread wrt a specific
368 : * |isolate|. Tasks posted for the same isolate should be execute in order of
369 : * scheduling. The definition of "foreground" is opaque to V8.
370 : */
371 : V8_DEPRECATE_SOON(
372 : "Use a taskrunner acquired by GetForegroundTaskRunner instead.",
373 : virtual void CallOnForegroundThread(Isolate* isolate, Task* task)) = 0;
374 :
375 : /**
376 : * Schedules a task to be invoked on a foreground thread wrt a specific
377 : * |isolate| after the given number of seconds |delay_in_seconds|.
378 : * Tasks posted for the same isolate should be execute in order of
379 : * scheduling. The definition of "foreground" is opaque to V8.
380 : */
381 : V8_DEPRECATE_SOON(
382 : "Use a taskrunner acquired by GetForegroundTaskRunner instead.",
383 : virtual void CallDelayedOnForegroundThread(Isolate* isolate, Task* task,
384 : double delay_in_seconds)) = 0;
385 :
386 : /**
387 : * Schedules a task to be invoked on a foreground thread wrt a specific
388 : * |isolate| when the embedder is idle.
389 : * Requires that SupportsIdleTasks(isolate) is true.
390 : * Idle tasks may be reordered relative to other task types and may be
391 : * starved for an arbitrarily long time if no idle time is available.
392 : * The definition of "foreground" is opaque to V8.
393 : */
394 0 : V8_DEPRECATE_SOON(
395 : "Use a taskrunner acquired by GetForegroundTaskRunner instead.",
396 : virtual void CallIdleOnForegroundThread(Isolate* isolate,
397 : IdleTask* task)) {
398 : // This must be overriden if |IdleTasksEnabled()|.
399 0 : abort();
400 : }
401 :
402 : /**
403 : * Returns true if idle tasks are enabled for the given |isolate|.
404 : */
405 0 : virtual bool IdleTasksEnabled(Isolate* isolate) {
406 0 : return false;
407 : }
408 :
409 : /**
410 : * Monotonically increasing time in seconds from an arbitrary fixed point in
411 : * the past. This function is expected to return at least
412 : * millisecond-precision values. For this reason,
413 : * it is recommended that the fixed point be no further in the past than
414 : * the epoch.
415 : **/
416 : virtual double MonotonicallyIncreasingTime() = 0;
417 :
418 : /**
419 : * Current wall-clock time in milliseconds since epoch.
420 : * This function is expected to return at least millisecond-precision values.
421 : */
422 : virtual double CurrentClockTimeMillis() = 0;
423 :
424 : typedef void (*StackTracePrinter)();
425 :
426 : /**
427 : * Returns a function pointer that print a stack trace of the current stack
428 : * on invocation. Disables printing of the stack trace if nullptr.
429 : */
430 0 : virtual StackTracePrinter GetStackTracePrinter() { return nullptr; }
431 :
432 : /**
433 : * Returns an instance of a v8::TracingController. This must be non-nullptr.
434 : */
435 : virtual TracingController* GetTracingController() = 0;
436 :
437 : /**
438 : * Tells the embedder to generate and upload a crashdump during an unexpected
439 : * but non-critical scenario.
440 : */
441 0 : virtual void DumpWithoutCrashing() {}
442 :
443 : protected:
444 : /**
445 : * Default implementation of current wall-clock time in milliseconds
446 : * since epoch. Useful for implementing |CurrentClockTimeMillis| if
447 : * nothing special needed.
448 : */
449 : V8_EXPORT static double SystemClockTimeMillis();
450 : };
451 :
452 : } // namespace v8
453 :
454 : #endif // V8_V8_PLATFORM_H_
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