LCOV - code coverage report
Current view: top level - include - v8-platform.h (source / functions) Hit Total Coverage
Test: app.info Lines: 9 27 33.3 %
Date: 2017-04-26 Functions: 0 21 0.0 %

          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 <memory>
      11             : #include <string>
      12             : 
      13             : namespace v8 {
      14             : 
      15             : class Isolate;
      16             : 
      17             : /**
      18             :  * A Task represents a unit of work.
      19             :  */
      20      803229 : class Task {
      21             :  public:
      22      803004 :   virtual ~Task() = default;
      23             : 
      24             :   virtual void Run() = 0;
      25             : };
      26             : 
      27             : /**
      28             :  * An IdleTask represents a unit of work to be performed in idle time.
      29             :  * The Run method is invoked with an argument that specifies the deadline in
      30             :  * seconds returned by MonotonicallyIncreasingTime().
      31             :  * The idle task is expected to complete by this deadline.
      32             :  */
      33        9156 : class IdleTask {
      34             :  public:
      35        9156 :   virtual ~IdleTask() = default;
      36             :   virtual void Run(double deadline_in_seconds) = 0;
      37             : };
      38             : 
      39             : /**
      40             :  * The interface represents complex arguments to trace events.
      41             :  */
      42        1747 : class ConvertableToTraceFormat {
      43             :  public:
      44        1747 :   virtual ~ConvertableToTraceFormat() = default;
      45             : 
      46             :   /**
      47             :    * Append the class info to the provided |out| string. The appended
      48             :    * data must be a valid JSON object. Strings must be properly quoted, and
      49             :    * escaped. There is no processing applied to the content after it is
      50             :    * appended.
      51             :    */
      52             :   virtual void AppendAsTraceFormat(std::string* out) const = 0;
      53             : };
      54             : 
      55             : /**
      56             :  * V8 Platform abstraction layer.
      57             :  *
      58             :  * The embedder has to provide an implementation of this interface before
      59             :  * initializing the rest of V8.
      60             :  */
      61             : class Platform {
      62             :  public:
      63             :   /**
      64             :    * This enum is used to indicate whether a task is potentially long running,
      65             :    * or causes a long wait. The embedder might want to use this hint to decide
      66             :    * whether to execute the task on a dedicated thread.
      67             :    */
      68             :   enum ExpectedRuntime {
      69             :     kShortRunningTask,
      70             :     kLongRunningTask
      71             :   };
      72             : 
      73       58750 :   virtual ~Platform() = default;
      74             : 
      75             :   /**
      76             :    * Gets the number of threads that are used to execute background tasks. Is
      77             :    * used to estimate the number of tasks a work package should be split into.
      78             :    * A return value of 0 means that there are no background threads available.
      79             :    * Note that a value of 0 won't prohibit V8 from posting tasks using
      80             :    * |CallOnBackgroundThread|.
      81             :    */
      82           0 :   virtual size_t NumberOfAvailableBackgroundThreads() { return 0; }
      83             : 
      84             :   /**
      85             :    * Schedules a task to be invoked on a background thread. |expected_runtime|
      86             :    * indicates that the task will run a long time. The Platform implementation
      87             :    * takes ownership of |task|. There is no guarantee about order of execution
      88             :    * of tasks wrt order of scheduling, nor is there a guarantee about the
      89             :    * thread the task will be run on.
      90             :    */
      91             :   virtual void CallOnBackgroundThread(Task* task,
      92             :                                       ExpectedRuntime expected_runtime) = 0;
      93             : 
      94             :   /**
      95             :    * Schedules a task to be invoked on a foreground thread wrt a specific
      96             :    * |isolate|. Tasks posted for the same isolate should be execute in order of
      97             :    * scheduling. The definition of "foreground" is opaque to V8.
      98             :    */
      99             :   virtual void CallOnForegroundThread(Isolate* isolate, Task* task) = 0;
     100             : 
     101             :   /**
     102             :    * Schedules a task to be invoked on a foreground thread wrt a specific
     103             :    * |isolate| after the given number of seconds |delay_in_seconds|.
     104             :    * Tasks posted for the same isolate should be execute in order of
     105             :    * scheduling. The definition of "foreground" is opaque to V8.
     106             :    */
     107             :   virtual void CallDelayedOnForegroundThread(Isolate* isolate, Task* task,
     108             :                                              double delay_in_seconds) = 0;
     109             : 
     110             :   /**
     111             :    * Schedules a task to be invoked on a foreground thread wrt a specific
     112             :    * |isolate| when the embedder is idle.
     113             :    * Requires that SupportsIdleTasks(isolate) is true.
     114             :    * Idle tasks may be reordered relative to other task types and may be
     115             :    * starved for an arbitrarily long time if no idle time is available.
     116             :    * The definition of "foreground" is opaque to V8.
     117             :    */
     118           0 :   virtual void CallIdleOnForegroundThread(Isolate* isolate, IdleTask* task) {
     119             :     // TODO(ulan): Make this function abstract after V8 roll in Chromium.
     120           0 :   }
     121             : 
     122             :   /**
     123             :    * Returns true if idle tasks are enabled for the given |isolate|.
     124             :    */
     125           0 :   virtual bool IdleTasksEnabled(Isolate* isolate) {
     126             :     // TODO(ulan): Make this function abstract after V8 roll in Chromium.
     127           0 :     return false;
     128             :   }
     129             : 
     130             :   /**
     131             :    * Monotonically increasing time in seconds from an arbitrary fixed point in
     132             :    * the past. This function is expected to return at least
     133             :    * millisecond-precision values. For this reason,
     134             :    * it is recommended that the fixed point be no further in the past than
     135             :    * the epoch.
     136             :    **/
     137             :   virtual double MonotonicallyIncreasingTime() = 0;
     138             : 
     139             :   /**
     140             :    * Called by TRACE_EVENT* macros, don't call this directly.
     141             :    * The name parameter is a category group for example:
     142             :    * TRACE_EVENT0("v8,parse", "V8.Parse")
     143             :    * The pointer returned points to a value with zero or more of the bits
     144             :    * defined in CategoryGroupEnabledFlags.
     145             :    **/
     146           0 :   virtual const uint8_t* GetCategoryGroupEnabled(const char* name) {
     147             :     static uint8_t no = 0;
     148           0 :     return &no;
     149             :   }
     150             : 
     151             :   /**
     152             :    * Gets the category group name of the given category_enabled_flag pointer.
     153             :    * Usually used while serliazing TRACE_EVENTs.
     154             :    **/
     155           0 :   virtual const char* GetCategoryGroupName(
     156             :       const uint8_t* category_enabled_flag) {
     157             :     static const char dummy[] = "dummy";
     158           0 :     return dummy;
     159             :   }
     160             : 
     161             :   /**
     162             :    * Adds a trace event to the platform tracing system. This function call is
     163             :    * usually the result of a TRACE_* macro from trace_event_common.h when
     164             :    * tracing and the category of the particular trace are enabled. It is not
     165             :    * advisable to call this function on its own; it is really only meant to be
     166             :    * used by the trace macros. The returned handle can be used by
     167             :    * UpdateTraceEventDuration to update the duration of COMPLETE events.
     168             :    */
     169           0 :   virtual uint64_t AddTraceEvent(
     170             :       char phase, const uint8_t* category_enabled_flag, const char* name,
     171             :       const char* scope, uint64_t id, uint64_t bind_id, int32_t num_args,
     172             :       const char** arg_names, const uint8_t* arg_types,
     173             :       const uint64_t* arg_values, unsigned int flags) {
     174           0 :     return 0;
     175             :   }
     176             : 
     177             :   /**
     178             :    * Adds a trace event to the platform tracing system. This function call is
     179             :    * usually the result of a TRACE_* macro from trace_event_common.h when
     180             :    * tracing and the category of the particular trace are enabled. It is not
     181             :    * advisable to call this function on its own; it is really only meant to be
     182             :    * used by the trace macros. The returned handle can be used by
     183             :    * UpdateTraceEventDuration to update the duration of COMPLETE events.
     184             :    */
     185           0 :   virtual uint64_t AddTraceEvent(
     186             :       char phase, const uint8_t* category_enabled_flag, const char* name,
     187             :       const char* scope, uint64_t id, uint64_t bind_id, int32_t num_args,
     188             :       const char** arg_names, const uint8_t* arg_types,
     189             :       const uint64_t* arg_values,
     190             :       std::unique_ptr<ConvertableToTraceFormat>* arg_convertables,
     191             :       unsigned int flags) {
     192             :     return AddTraceEvent(phase, category_enabled_flag, name, scope, id, bind_id,
     193           0 :                          num_args, arg_names, arg_types, arg_values, flags);
     194             :   }
     195             : 
     196             :   /**
     197             :    * Sets the duration field of a COMPLETE trace event. It must be called with
     198             :    * the handle returned from AddTraceEvent().
     199             :    **/
     200           0 :   virtual void UpdateTraceEventDuration(const uint8_t* category_enabled_flag,
     201           0 :                                         const char* name, uint64_t handle) {}
     202             : 
     203       59467 :   class TraceStateObserver {
     204             :    public:
     205       58750 :     virtual ~TraceStateObserver() = default;
     206             :     virtual void OnTraceEnabled() = 0;
     207             :     virtual void OnTraceDisabled() = 0;
     208             :   };
     209             : 
     210             :   /** Adds tracing state change observer. */
     211           0 :   virtual void AddTraceStateObserver(TraceStateObserver*) {}
     212             : 
     213             :   /** Removes tracing state change observer. */
     214           0 :   virtual void RemoveTraceStateObserver(TraceStateObserver*) {}
     215             : 
     216             :   typedef void (*StackTracePrinter)();
     217             : 
     218             :   /**
     219             :    * Returns a function pointer that print a stack trace of the current stack
     220             :    * on invocation. Disables printing of the stack trace if nullptr.
     221             :    */
     222           0 :   virtual StackTracePrinter GetStackTracePrinter() { return nullptr; }
     223             : };
     224             : 
     225             : }  // namespace v8
     226             : 
     227             : #endif  // V8_V8_PLATFORM_H_

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