v8  10.1.124 (node 18.2.0)
V8 is Google's open source JavaScript engine
libplatform.h
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1 // Copyright 2014 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_LIBPLATFORM_LIBPLATFORM_H_
6 #define V8_LIBPLATFORM_LIBPLATFORM_H_
7 
8 #include <memory>
9 
10 #include "libplatform/libplatform-export.h"
11 #include "libplatform/v8-tracing.h"
12 #include "v8-platform.h" // NOLINT(build/include_directory)
13 #include "v8config.h" // NOLINT(build/include_directory)
14 
15 namespace v8 {
16 namespace platform {
17 
20 
21 enum class MessageLoopBehavior : bool {
22  kDoNotWait = false,
23  kWaitForWork = true
24 };
25 
26 /**
27  * Returns a new instance of the default v8::Platform implementation.
28  *
29  * The caller will take ownership of the returned pointer. |thread_pool_size|
30  * is the number of worker threads to allocate for background jobs. If a value
31  * of zero is passed, a suitable default based on the current number of
32  * processors online will be chosen.
33  * If |idle_task_support| is enabled then the platform will accept idle
34  * tasks (IdleTasksEnabled will return true) and will rely on the embedder
35  * calling v8::platform::RunIdleTasks to process the idle tasks.
36  * If |tracing_controller| is nullptr, the default platform will create a
37  * v8::platform::TracingController instance and use it.
38  */
40  int thread_pool_size = 0,
41  IdleTaskSupport idle_task_support = IdleTaskSupport::kDisabled,
42  InProcessStackDumping in_process_stack_dumping =
44  std::unique_ptr<v8::TracingController> tracing_controller = {});
45 
46 /**
47  * The same as NewDefaultPlatform but disables the worker thread pool.
48  * It must be used with the --single-threaded V8 flag.
49  */
50 V8_PLATFORM_EXPORT std::unique_ptr<v8::Platform>
52  IdleTaskSupport idle_task_support = IdleTaskSupport::kDisabled,
53  InProcessStackDumping in_process_stack_dumping =
55  std::unique_ptr<v8::TracingController> tracing_controller = {});
56 
57 /**
58  * Returns a new instance of the default v8::JobHandle implementation.
59  *
60  * The job will be executed by spawning up to |num_worker_threads| many worker
61  * threads on the provided |platform| with the given |priority|.
62  */
64  v8::Platform* platform, v8::TaskPriority priority,
65  std::unique_ptr<v8::JobTask> job_task, size_t num_worker_threads);
66 
67 /**
68  * Pumps the message loop for the given isolate.
69  *
70  * The caller has to make sure that this is called from the right thread.
71  * Returns true if a task was executed, and false otherwise. If the call to
72  * PumpMessageLoop is nested within another call to PumpMessageLoop, only
73  * nestable tasks may run. Otherwise, any task may run. Unless requested through
74  * the |behavior| parameter, this call does not block if no task is pending. The
75  * |platform| has to be created using |NewDefaultPlatform|.
76  */
78  v8::Platform* platform, v8::Isolate* isolate,
80 
81 /**
82  * Runs pending idle tasks for at most |idle_time_in_seconds| seconds.
83  *
84  * The caller has to make sure that this is called from the right thread.
85  * This call does not block if no task is pending. The |platform| has to be
86  * created using |NewDefaultPlatform|.
87  */
89  v8::Isolate* isolate,
90  double idle_time_in_seconds);
91 
92 /**
93  * Notifies the given platform about the Isolate getting deleted soon. Has to be
94  * called for all Isolates which are deleted - unless we're shutting down the
95  * platform.
96  *
97  * The |platform| has to be created using |NewDefaultPlatform|.
98  *
99  */
101  Isolate* isolate);
102 
103 } // namespace platform
104 } // namespace v8
105 
106 #endif // V8_LIBPLATFORM_LIBPLATFORM_H_