LCOV - code coverage report
Current view: top level - include - v8-profiler.h (source / functions) Hit Total Coverage
Test: app.info Lines: 15 23 65.2 %
Date: 2017-04-26 Functions: 3 20 15.0 %

          Line data    Source code
       1             : // Copyright 2010 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_PROFILER_H_
       6             : #define V8_V8_PROFILER_H_
       7             : 
       8             : #include <unordered_set>
       9             : #include <vector>
      10             : #include "v8.h"  // NOLINT(build/include)
      11             : 
      12             : /**
      13             :  * Profiler support for the V8 JavaScript engine.
      14             :  */
      15             : namespace v8 {
      16             : 
      17             : class HeapGraphNode;
      18             : struct HeapStatsUpdate;
      19             : 
      20             : typedef uint32_t SnapshotObjectId;
      21             : 
      22             : 
      23             : struct CpuProfileDeoptFrame {
      24             :   int script_id;
      25             :   size_t position;
      26             : };
      27             : 
      28             : }  // namespace v8
      29             : 
      30             : #ifdef V8_OS_WIN
      31             : template class V8_EXPORT std::vector<v8::CpuProfileDeoptFrame>;
      32             : #endif
      33             : 
      34             : namespace v8 {
      35             : 
      36          29 : struct V8_EXPORT CpuProfileDeoptInfo {
      37             :   /** A pointer to a static string owned by v8. */
      38             :   const char* deopt_reason;
      39             :   std::vector<CpuProfileDeoptFrame> stack;
      40             : };
      41             : 
      42             : }  // namespace v8
      43             : 
      44             : #ifdef V8_OS_WIN
      45             : template class V8_EXPORT std::vector<v8::CpuProfileDeoptInfo>;
      46             : #endif
      47             : 
      48             : namespace v8 {
      49             : 
      50             : /**
      51             :  * TracingCpuProfiler monitors tracing being enabled/disabled
      52             :  * and emits CpuProfile trace events once v8.cpu_profiler tracing category
      53             :  * is enabled. It has no overhead unless the category is enabled.
      54             :  */
      55             : class V8_EXPORT TracingCpuProfiler {
      56             :  public:
      57             :   static std::unique_ptr<TracingCpuProfiler> Create(Isolate*);
      58           6 :   virtual ~TracingCpuProfiler() = default;
      59             : 
      60             :  protected:
      61           6 :   TracingCpuProfiler() = default;
      62             : };
      63             : 
      64             : // TickSample captures the information collected for each sample.
      65             : struct TickSample {
      66             :   // Internal profiling (with --prof + tools/$OS-tick-processor) wants to
      67             :   // include the runtime function we're calling. Externally exposed tick
      68             :   // samples don't care.
      69             :   enum RecordCEntryFrame { kIncludeCEntryFrame, kSkipCEntryFrame };
      70             : 
      71             :   TickSample()
      72             :       : state(OTHER),
      73             :         pc(nullptr),
      74             :         external_callback_entry(nullptr),
      75             :         frames_count(0),
      76             :         has_external_callback(false),
      77     1269967 :         update_stats(true) {}
      78             : 
      79             :   /**
      80             :    * Initialize a tick sample from the isolate.
      81             :    * \param isolate The isolate.
      82             :    * \param state Execution state.
      83             :    * \param record_c_entry_frame Include or skip the runtime function.
      84             :    * \param update_stats Whether update the sample to the aggregated stats.
      85             :    * \param use_simulator_reg_state When set to true and V8 is running under a
      86             :    *                                simulator, the method will use the simulator
      87             :    *                                register state rather than the one provided
      88             :    *                                with |state| argument. Otherwise the method
      89             :    *                                will use provided register |state| as is.
      90             :    */
      91             :   void Init(Isolate* isolate, const v8::RegisterState& state,
      92             :             RecordCEntryFrame record_c_entry_frame, bool update_stats,
      93             :             bool use_simulator_reg_state = true);
      94             :   /**
      95             :    * Get a call stack sample from the isolate.
      96             :    * \param isolate The isolate.
      97             :    * \param state Register state.
      98             :    * \param record_c_entry_frame Include or skip the runtime function.
      99             :    * \param frames Caller allocated buffer to store stack frames.
     100             :    * \param frames_limit Maximum number of frames to capture. The buffer must
     101             :    *                     be large enough to hold the number of frames.
     102             :    * \param sample_info The sample info is filled up by the function
     103             :    *                    provides number of actual captured stack frames and
     104             :    *                    the current VM state.
     105             :    * \param use_simulator_reg_state When set to true and V8 is running under a
     106             :    *                                simulator, the method will use the simulator
     107             :    *                                register state rather than the one provided
     108             :    *                                with |state| argument. Otherwise the method
     109             :    *                                will use provided register |state| as is.
     110             :    * \note GetStackSample is thread and signal safe and should only be called
     111             :    *                      when the JS thread is paused or interrupted.
     112             :    *                      Otherwise the behavior is undefined.
     113             :    */
     114             :   static bool GetStackSample(Isolate* isolate, v8::RegisterState* state,
     115             :                              RecordCEntryFrame record_c_entry_frame,
     116             :                              void** frames, size_t frames_limit,
     117             :                              v8::SampleInfo* sample_info,
     118             :                              bool use_simulator_reg_state = true);
     119             :   StateTag state;  // The state of the VM.
     120             :   void* pc;        // Instruction pointer.
     121             :   union {
     122             :     void* tos;  // Top stack value (*sp).
     123             :     void* external_callback_entry;
     124             :   };
     125             :   static const unsigned kMaxFramesCountLog2 = 8;
     126             :   static const unsigned kMaxFramesCount = (1 << kMaxFramesCountLog2) - 1;
     127             :   void* stack[kMaxFramesCount];                 // Call stack.
     128             :   unsigned frames_count : kMaxFramesCountLog2;  // Number of captured frames.
     129             :   bool has_external_callback : 1;
     130             :   bool update_stats : 1;  // Whether the sample should update aggregated stats.
     131             : };
     132             : 
     133             : /**
     134             :  * CpuProfileNode represents a node in a call graph.
     135             :  */
     136             : class V8_EXPORT CpuProfileNode {
     137             :  public:
     138             :   struct LineTick {
     139             :     /** The 1-based number of the source line where the function originates. */
     140             :     int line;
     141             : 
     142             :     /** The count of samples associated with the source line. */
     143             :     unsigned int hit_count;
     144             :   };
     145             : 
     146             :   /** Returns function name (empty string for anonymous functions.) */
     147             :   Local<String> GetFunctionName() const;
     148             : 
     149             :   /**
     150             :    * Returns function name (empty string for anonymous functions.)
     151             :    * The string ownership is *not* passed to the caller. It stays valid until
     152             :    * profile is deleted. The function is thread safe.
     153             :    */
     154             :   const char* GetFunctionNameStr() const;
     155             : 
     156             :   /** Returns id of the script where function is located. */
     157             :   int GetScriptId() const;
     158             : 
     159             :   /** Returns resource name for script from where the function originates. */
     160             :   Local<String> GetScriptResourceName() const;
     161             : 
     162             :   /**
     163             :    * Returns resource name for script from where the function originates.
     164             :    * The string ownership is *not* passed to the caller. It stays valid until
     165             :    * profile is deleted. The function is thread safe.
     166             :    */
     167             :   const char* GetScriptResourceNameStr() const;
     168             : 
     169             :   /**
     170             :    * Returns the number, 1-based, of the line where the function originates.
     171             :    * kNoLineNumberInfo if no line number information is available.
     172             :    */
     173             :   int GetLineNumber() const;
     174             : 
     175             :   /**
     176             :    * Returns 1-based number of the column where the function originates.
     177             :    * kNoColumnNumberInfo if no column number information is available.
     178             :    */
     179             :   int GetColumnNumber() const;
     180             : 
     181             :   /**
     182             :    * Returns the number of the function's source lines that collect the samples.
     183             :    */
     184             :   unsigned int GetHitLineCount() const;
     185             : 
     186             :   /** Returns the set of source lines that collect the samples.
     187             :    *  The caller allocates buffer and responsible for releasing it.
     188             :    *  True if all available entries are copied, otherwise false.
     189             :    *  The function copies nothing if buffer is not large enough.
     190             :    */
     191             :   bool GetLineTicks(LineTick* entries, unsigned int length) const;
     192             : 
     193             :   /** Returns bailout reason for the function
     194             :     * if the optimization was disabled for it.
     195             :     */
     196             :   const char* GetBailoutReason() const;
     197             : 
     198             :   /**
     199             :     * Returns the count of samples where the function was currently executing.
     200             :     */
     201             :   unsigned GetHitCount() const;
     202             : 
     203             :   /** Returns function entry UID. */
     204             :   V8_DEPRECATE_SOON(
     205             :       "Use GetScriptId, GetLineNumber, and GetColumnNumber instead.",
     206             :       unsigned GetCallUid() const);
     207             : 
     208             :   /** Returns id of the node. The id is unique within the tree */
     209             :   unsigned GetNodeId() const;
     210             : 
     211             :   /** Returns child nodes count of the node. */
     212             :   int GetChildrenCount() const;
     213             : 
     214             :   /** Retrieves a child node by index. */
     215             :   const CpuProfileNode* GetChild(int index) const;
     216             : 
     217             :   /** Retrieves deopt infos for the node. */
     218             :   const std::vector<CpuProfileDeoptInfo>& GetDeoptInfos() const;
     219             : 
     220             :   static const int kNoLineNumberInfo = Message::kNoLineNumberInfo;
     221             :   static const int kNoColumnNumberInfo = Message::kNoColumnInfo;
     222             : };
     223             : 
     224             : 
     225             : /**
     226             :  * CpuProfile contains a CPU profile in a form of top-down call tree
     227             :  * (from main() down to functions that do all the work).
     228             :  */
     229             : class V8_EXPORT CpuProfile {
     230             :  public:
     231             :   /** Returns CPU profile title. */
     232             :   Local<String> GetTitle() const;
     233             : 
     234             :   /** Returns the root node of the top down call tree. */
     235             :   const CpuProfileNode* GetTopDownRoot() const;
     236             : 
     237             :   /**
     238             :    * Returns number of samples recorded. The samples are not recorded unless
     239             :    * |record_samples| parameter of CpuProfiler::StartCpuProfiling is true.
     240             :    */
     241             :   int GetSamplesCount() const;
     242             : 
     243             :   /**
     244             :    * Returns profile node corresponding to the top frame the sample at
     245             :    * the given index.
     246             :    */
     247             :   const CpuProfileNode* GetSample(int index) const;
     248             : 
     249             :   /**
     250             :    * Returns the timestamp of the sample. The timestamp is the number of
     251             :    * microseconds since some unspecified starting point.
     252             :    * The point is equal to the starting point used by GetStartTime.
     253             :    */
     254             :   int64_t GetSampleTimestamp(int index) const;
     255             : 
     256             :   /**
     257             :    * Returns time when the profile recording was started (in microseconds)
     258             :    * since some unspecified starting point.
     259             :    */
     260             :   int64_t GetStartTime() const;
     261             : 
     262             :   /**
     263             :    * Returns time when the profile recording was stopped (in microseconds)
     264             :    * since some unspecified starting point.
     265             :    * The point is equal to the starting point used by GetStartTime.
     266             :    */
     267             :   int64_t GetEndTime() const;
     268             : 
     269             :   /**
     270             :    * Deletes the profile and removes it from CpuProfiler's list.
     271             :    * All pointers to nodes previously returned become invalid.
     272             :    */
     273             :   void Delete();
     274             : };
     275             : 
     276             : /**
     277             :  * Interface for controlling CPU profiling. Instance of the
     278             :  * profiler can be created using v8::CpuProfiler::New method.
     279             :  */
     280             : class V8_EXPORT CpuProfiler {
     281             :  public:
     282             :   /**
     283             :    * Creates a new CPU profiler for the |isolate|. The isolate must be
     284             :    * initialized. The profiler object must be disposed after use by calling
     285             :    * |Dispose| method.
     286             :    */
     287             :   static CpuProfiler* New(Isolate* isolate);
     288             : 
     289             :   /**
     290             :    * Disposes the CPU profiler object.
     291             :    */
     292             :   void Dispose();
     293             : 
     294             :   /**
     295             :    * Changes default CPU profiler sampling interval to the specified number
     296             :    * of microseconds. Default interval is 1000us. This method must be called
     297             :    * when there are no profiles being recorded.
     298             :    */
     299             :   void SetSamplingInterval(int us);
     300             : 
     301             :   /**
     302             :    * Starts collecting CPU profile. Title may be an empty string. It
     303             :    * is allowed to have several profiles being collected at
     304             :    * once. Attempts to start collecting several profiles with the same
     305             :    * title are silently ignored. While collecting a profile, functions
     306             :    * from all security contexts are included in it. The token-based
     307             :    * filtering is only performed when querying for a profile.
     308             :    *
     309             :    * |record_samples| parameter controls whether individual samples should
     310             :    * be recorded in addition to the aggregated tree.
     311             :    */
     312             :   void StartProfiling(Local<String> title, bool record_samples = false);
     313             : 
     314             :   /**
     315             :    * Stops collecting CPU profile with a given title and returns it.
     316             :    * If the title given is empty, finishes the last profile started.
     317             :    */
     318             :   CpuProfile* StopProfiling(Local<String> title);
     319             : 
     320             :   /**
     321             :    * Force collection of a sample. Must be called on the VM thread.
     322             :    * Recording the forced sample does not contribute to the aggregated
     323             :    * profile statistics.
     324             :    */
     325             :   void CollectSample();
     326             : 
     327             :   /**
     328             :    * Tells the profiler whether the embedder is idle.
     329             :    */
     330             :   void SetIdle(bool is_idle);
     331             : 
     332             :  private:
     333             :   CpuProfiler();
     334             :   ~CpuProfiler();
     335             :   CpuProfiler(const CpuProfiler&);
     336             :   CpuProfiler& operator=(const CpuProfiler&);
     337             : };
     338             : 
     339             : 
     340             : /**
     341             :  * HeapSnapshotEdge represents a directed connection between heap
     342             :  * graph nodes: from retainers to retained nodes.
     343             :  */
     344             : class V8_EXPORT HeapGraphEdge {
     345             :  public:
     346             :   enum Type {
     347             :     kContextVariable = 0,  // A variable from a function context.
     348             :     kElement = 1,          // An element of an array.
     349             :     kProperty = 2,         // A named object property.
     350             :     kInternal = 3,         // A link that can't be accessed from JS,
     351             :                            // thus, its name isn't a real property name
     352             :                            // (e.g. parts of a ConsString).
     353             :     kHidden = 4,           // A link that is needed for proper sizes
     354             :                            // calculation, but may be hidden from user.
     355             :     kShortcut = 5,         // A link that must not be followed during
     356             :                            // sizes calculation.
     357             :     kWeak = 6              // A weak reference (ignored by the GC).
     358             :   };
     359             : 
     360             :   /** Returns edge type (see HeapGraphEdge::Type). */
     361             :   Type GetType() const;
     362             : 
     363             :   /**
     364             :    * Returns edge name. This can be a variable name, an element index, or
     365             :    * a property name.
     366             :    */
     367             :   Local<Value> GetName() const;
     368             : 
     369             :   /** Returns origin node. */
     370             :   const HeapGraphNode* GetFromNode() const;
     371             : 
     372             :   /** Returns destination node. */
     373             :   const HeapGraphNode* GetToNode() const;
     374             : };
     375             : 
     376             : 
     377             : /**
     378             :  * HeapGraphNode represents a node in a heap graph.
     379             :  */
     380             : class V8_EXPORT HeapGraphNode {
     381             :  public:
     382             :   enum Type {
     383             :     kHidden = 0,         // Hidden node, may be filtered when shown to user.
     384             :     kArray = 1,          // An array of elements.
     385             :     kString = 2,         // A string.
     386             :     kObject = 3,         // A JS object (except for arrays and strings).
     387             :     kCode = 4,           // Compiled code.
     388             :     kClosure = 5,        // Function closure.
     389             :     kRegExp = 6,         // RegExp.
     390             :     kHeapNumber = 7,     // Number stored in the heap.
     391             :     kNative = 8,         // Native object (not from V8 heap).
     392             :     kSynthetic = 9,      // Synthetic object, usualy used for grouping
     393             :                          // snapshot items together.
     394             :     kConsString = 10,    // Concatenated string. A pair of pointers to strings.
     395             :     kSlicedString = 11,  // Sliced string. A fragment of another string.
     396             :     kSymbol = 12         // A Symbol (ES6).
     397             :   };
     398             : 
     399             :   /** Returns node type (see HeapGraphNode::Type). */
     400             :   Type GetType() const;
     401             : 
     402             :   /**
     403             :    * Returns node name. Depending on node's type this can be the name
     404             :    * of the constructor (for objects), the name of the function (for
     405             :    * closures), string value, or an empty string (for compiled code).
     406             :    */
     407             :   Local<String> GetName() const;
     408             : 
     409             :   /**
     410             :    * Returns node id. For the same heap object, the id remains the same
     411             :    * across all snapshots.
     412             :    */
     413             :   SnapshotObjectId GetId() const;
     414             : 
     415             :   /** Returns node's own size, in bytes. */
     416             :   size_t GetShallowSize() const;
     417             : 
     418             :   /** Returns child nodes count of the node. */
     419             :   int GetChildrenCount() const;
     420             : 
     421             :   /** Retrieves a child by index. */
     422             :   const HeapGraphEdge* GetChild(int index) const;
     423             : };
     424             : 
     425             : 
     426             : /**
     427             :  * An interface for exporting data from V8, using "push" model.
     428             :  */
     429          12 : class V8_EXPORT OutputStream {  // NOLINT
     430             :  public:
     431             :   enum WriteResult {
     432             :     kContinue = 0,
     433             :     kAbort = 1
     434             :   };
     435          12 :   virtual ~OutputStream() {}
     436             :   /** Notify about the end of stream. */
     437             :   virtual void EndOfStream() = 0;
     438             :   /** Get preferred output chunk size. Called only once. */
     439           0 :   virtual int GetChunkSize() { return 1024; }
     440             :   /**
     441             :    * Writes the next chunk of snapshot data into the stream. Writing
     442             :    * can be stopped by returning kAbort as function result. EndOfStream
     443             :    * will not be called in case writing was aborted.
     444             :    */
     445             :   virtual WriteResult WriteAsciiChunk(char* data, int size) = 0;
     446             :   /**
     447             :    * Writes the next chunk of heap stats data into the stream. Writing
     448             :    * can be stopped by returning kAbort as function result. EndOfStream
     449             :    * will not be called in case writing was aborted.
     450             :    */
     451           0 :   virtual WriteResult WriteHeapStatsChunk(HeapStatsUpdate* data, int count) {
     452           0 :     return kAbort;
     453             :   }
     454             : };
     455             : 
     456             : 
     457             : /**
     458             :  * HeapSnapshots record the state of the JS heap at some moment.
     459             :  */
     460             : class V8_EXPORT HeapSnapshot {
     461             :  public:
     462             :   enum SerializationFormat {
     463             :     kJSON = 0  // See format description near 'Serialize' method.
     464             :   };
     465             : 
     466             :   /** Returns the root node of the heap graph. */
     467             :   const HeapGraphNode* GetRoot() const;
     468             : 
     469             :   /** Returns a node by its id. */
     470             :   const HeapGraphNode* GetNodeById(SnapshotObjectId id) const;
     471             : 
     472             :   /** Returns total nodes count in the snapshot. */
     473             :   int GetNodesCount() const;
     474             : 
     475             :   /** Returns a node by index. */
     476             :   const HeapGraphNode* GetNode(int index) const;
     477             : 
     478             :   /** Returns a max seen JS object Id. */
     479             :   SnapshotObjectId GetMaxSnapshotJSObjectId() const;
     480             : 
     481             :   /**
     482             :    * Deletes the snapshot and removes it from HeapProfiler's list.
     483             :    * All pointers to nodes, edges and paths previously returned become
     484             :    * invalid.
     485             :    */
     486             :   void Delete();
     487             : 
     488             :   /**
     489             :    * Prepare a serialized representation of the snapshot. The result
     490             :    * is written into the stream provided in chunks of specified size.
     491             :    * The total length of the serialized snapshot is unknown in
     492             :    * advance, it can be roughly equal to JS heap size (that means,
     493             :    * it can be really big - tens of megabytes).
     494             :    *
     495             :    * For the JSON format, heap contents are represented as an object
     496             :    * with the following structure:
     497             :    *
     498             :    *  {
     499             :    *    snapshot: {
     500             :    *      title: "...",
     501             :    *      uid: nnn,
     502             :    *      meta: { meta-info },
     503             :    *      node_count: nnn,
     504             :    *      edge_count: nnn
     505             :    *    },
     506             :    *    nodes: [nodes array],
     507             :    *    edges: [edges array],
     508             :    *    strings: [strings array]
     509             :    *  }
     510             :    *
     511             :    * Nodes reference strings, other nodes, and edges by their indexes
     512             :    * in corresponding arrays.
     513             :    */
     514             :   void Serialize(OutputStream* stream,
     515             :                  SerializationFormat format = kJSON) const;
     516             : };
     517             : 
     518             : 
     519             : /**
     520             :  * An interface for reporting progress and controlling long-running
     521             :  * activities.
     522             :  */
     523           0 : class V8_EXPORT ActivityControl {  // NOLINT
     524             :  public:
     525             :   enum ControlOption {
     526             :     kContinue = 0,
     527             :     kAbort = 1
     528             :   };
     529           0 :   virtual ~ActivityControl() {}
     530             :   /**
     531             :    * Notify about current progress. The activity can be stopped by
     532             :    * returning kAbort as the callback result.
     533             :    */
     534             :   virtual ControlOption ReportProgressValue(int done, int total) = 0;
     535             : };
     536             : 
     537             : 
     538             : /**
     539             :  * AllocationProfile is a sampled profile of allocations done by the program.
     540             :  * This is structured as a call-graph.
     541             :  */
     542          30 : class V8_EXPORT AllocationProfile {
     543             :  public:
     544             :   struct Allocation {
     545             :     /**
     546             :      * Size of the sampled allocation object.
     547             :      */
     548             :     size_t size;
     549             : 
     550             :     /**
     551             :      * The number of objects of such size that were sampled.
     552             :      */
     553             :     unsigned int count;
     554             :   };
     555             : 
     556             :   /**
     557             :    * Represents a node in the call-graph.
     558             :    */
     559        1596 :   struct Node {
     560             :     /**
     561             :      * Name of the function. May be empty for anonymous functions or if the
     562             :      * script corresponding to this function has been unloaded.
     563             :      */
     564             :     Local<String> name;
     565             : 
     566             :     /**
     567             :      * Name of the script containing the function. May be empty if the script
     568             :      * name is not available, or if the script has been unloaded.
     569             :      */
     570             :     Local<String> script_name;
     571             : 
     572             :     /**
     573             :      * id of the script where the function is located. May be equal to
     574             :      * v8::UnboundScript::kNoScriptId in cases where the script doesn't exist.
     575             :      */
     576             :     int script_id;
     577             : 
     578             :     /**
     579             :      * Start position of the function in the script.
     580             :      */
     581             :     int start_position;
     582             : 
     583             :     /**
     584             :      * 1-indexed line number where the function starts. May be
     585             :      * kNoLineNumberInfo if no line number information is available.
     586             :      */
     587             :     int line_number;
     588             : 
     589             :     /**
     590             :      * 1-indexed column number where the function starts. May be
     591             :      * kNoColumnNumberInfo if no line number information is available.
     592             :      */
     593             :     int column_number;
     594             : 
     595             :     /**
     596             :      * List of callees called from this node for which we have sampled
     597             :      * allocations. The lifetime of the children is scoped to the containing
     598             :      * AllocationProfile.
     599             :      */
     600             :     std::vector<Node*> children;
     601             : 
     602             :     /**
     603             :      * List of self allocations done by this node in the call-graph.
     604             :      */
     605             :     std::vector<Allocation> allocations;
     606             :   };
     607             : 
     608             :   /**
     609             :    * Returns the root node of the call-graph. The root node corresponds to an
     610             :    * empty JS call-stack. The lifetime of the returned Node* is scoped to the
     611             :    * containing AllocationProfile.
     612             :    */
     613             :   virtual Node* GetRootNode() = 0;
     614             : 
     615          30 :   virtual ~AllocationProfile() {}
     616             : 
     617             :   static const int kNoLineNumberInfo = Message::kNoLineNumberInfo;
     618             :   static const int kNoColumnNumberInfo = Message::kNoColumnInfo;
     619             : };
     620             : 
     621             : 
     622             : /**
     623             :  * Interface for controlling heap profiling. Instance of the
     624             :  * profiler can be retrieved using v8::Isolate::GetHeapProfiler.
     625             :  */
     626             : class V8_EXPORT HeapProfiler {
     627             :  public:
     628             :   enum SamplingFlags {
     629             :     kSamplingNoFlags = 0,
     630             :     kSamplingForceGC = 1 << 0,
     631             :   };
     632             : 
     633             :   typedef std::unordered_set<const v8::PersistentBase<v8::Value>*>
     634             :       RetainerChildren;
     635             :   typedef std::vector<std::pair<v8::RetainedObjectInfo*, RetainerChildren>>
     636             :       RetainerGroups;
     637             :   typedef std::vector<std::pair<const v8::PersistentBase<v8::Value>*,
     638             :                                 const v8::PersistentBase<v8::Value>*>>
     639             :       RetainerEdges;
     640             : 
     641         730 :   struct RetainerInfos {
     642             :     RetainerGroups groups;
     643             :     RetainerEdges edges;
     644             :   };
     645             : 
     646             :   /**
     647             :    * Callback function invoked to retrieve all RetainerInfos from the embedder.
     648             :    */
     649             :   typedef RetainerInfos (*GetRetainerInfosCallback)(v8::Isolate* isolate);
     650             : 
     651             :   /**
     652             :    * Callback function invoked for obtaining RetainedObjectInfo for
     653             :    * the given JavaScript wrapper object. It is prohibited to enter V8
     654             :    * while the callback is running: only getters on the handle and
     655             :    * GetPointerFromInternalField on the objects are allowed.
     656             :    */
     657             :   typedef RetainedObjectInfo* (*WrapperInfoCallback)(uint16_t class_id,
     658             :                                                      Local<Value> wrapper);
     659             : 
     660             :   /** Returns the number of snapshots taken. */
     661             :   int GetSnapshotCount();
     662             : 
     663             :   /** Returns a snapshot by index. */
     664             :   const HeapSnapshot* GetHeapSnapshot(int index);
     665             : 
     666             :   /**
     667             :    * Returns SnapshotObjectId for a heap object referenced by |value| if
     668             :    * it has been seen by the heap profiler, kUnknownObjectId otherwise.
     669             :    */
     670             :   SnapshotObjectId GetObjectId(Local<Value> value);
     671             : 
     672             :   /**
     673             :    * Returns heap object with given SnapshotObjectId if the object is alive,
     674             :    * otherwise empty handle is returned.
     675             :    */
     676             :   Local<Value> FindObjectById(SnapshotObjectId id);
     677             : 
     678             :   /**
     679             :    * Clears internal map from SnapshotObjectId to heap object. The new objects
     680             :    * will not be added into it unless a heap snapshot is taken or heap object
     681             :    * tracking is kicked off.
     682             :    */
     683             :   void ClearObjectIds();
     684             : 
     685             :   /**
     686             :    * A constant for invalid SnapshotObjectId. GetSnapshotObjectId will return
     687             :    * it in case heap profiler cannot find id  for the object passed as
     688             :    * parameter. HeapSnapshot::GetNodeById will always return NULL for such id.
     689             :    */
     690             :   static const SnapshotObjectId kUnknownObjectId = 0;
     691             : 
     692             :   /**
     693             :    * Callback interface for retrieving user friendly names of global objects.
     694             :    */
     695          12 :   class ObjectNameResolver {
     696             :    public:
     697             :     /**
     698             :      * Returns name to be used in the heap snapshot for given node. Returned
     699             :      * string must stay alive until snapshot collection is completed.
     700             :      */
     701             :     virtual const char* GetName(Local<Object> object) = 0;
     702             : 
     703             :    protected:
     704          12 :     virtual ~ObjectNameResolver() {}
     705             :   };
     706             : 
     707             :   /**
     708             :    * Takes a heap snapshot and returns it.
     709             :    */
     710             :   const HeapSnapshot* TakeHeapSnapshot(
     711             :       ActivityControl* control = NULL,
     712             :       ObjectNameResolver* global_object_name_resolver = NULL);
     713             : 
     714             :   /**
     715             :    * Starts tracking of heap objects population statistics. After calling
     716             :    * this method, all heap objects relocations done by the garbage collector
     717             :    * are being registered.
     718             :    *
     719             :    * |track_allocations| parameter controls whether stack trace of each
     720             :    * allocation in the heap will be recorded and reported as part of
     721             :    * HeapSnapshot.
     722             :    */
     723             :   void StartTrackingHeapObjects(bool track_allocations = false);
     724             : 
     725             :   /**
     726             :    * Adds a new time interval entry to the aggregated statistics array. The
     727             :    * time interval entry contains information on the current heap objects
     728             :    * population size. The method also updates aggregated statistics and
     729             :    * reports updates for all previous time intervals via the OutputStream
     730             :    * object. Updates on each time interval are provided as a stream of the
     731             :    * HeapStatsUpdate structure instances.
     732             :    * If |timestamp_us| is supplied, timestamp of the new entry will be written
     733             :    * into it. The return value of the function is the last seen heap object Id.
     734             :    *
     735             :    * StartTrackingHeapObjects must be called before the first call to this
     736             :    * method.
     737             :    */
     738             :   SnapshotObjectId GetHeapStats(OutputStream* stream,
     739             :                                 int64_t* timestamp_us = NULL);
     740             : 
     741             :   /**
     742             :    * Stops tracking of heap objects population statistics, cleans up all
     743             :    * collected data. StartHeapObjectsTracking must be called again prior to
     744             :    * calling GetHeapStats next time.
     745             :    */
     746             :   void StopTrackingHeapObjects();
     747             : 
     748             :   /**
     749             :    * Starts gathering a sampling heap profile. A sampling heap profile is
     750             :    * similar to tcmalloc's heap profiler and Go's mprof. It samples object
     751             :    * allocations and builds an online 'sampling' heap profile. At any point in
     752             :    * time, this profile is expected to be a representative sample of objects
     753             :    * currently live in the system. Each sampled allocation includes the stack
     754             :    * trace at the time of allocation, which makes this really useful for memory
     755             :    * leak detection.
     756             :    *
     757             :    * This mechanism is intended to be cheap enough that it can be used in
     758             :    * production with minimal performance overhead.
     759             :    *
     760             :    * Allocations are sampled using a randomized Poisson process. On average, one
     761             :    * allocation will be sampled every |sample_interval| bytes allocated. The
     762             :    * |stack_depth| parameter controls the maximum number of stack frames to be
     763             :    * captured on each allocation.
     764             :    *
     765             :    * NOTE: This is a proof-of-concept at this point. Right now we only sample
     766             :    * newspace allocations. Support for paged space allocation (e.g. pre-tenured
     767             :    * objects, large objects, code objects, etc.) and native allocations
     768             :    * doesn't exist yet, but is anticipated in the future.
     769             :    *
     770             :    * Objects allocated before the sampling is started will not be included in
     771             :    * the profile.
     772             :    *
     773             :    * Returns false if a sampling heap profiler is already running.
     774             :    */
     775             :   bool StartSamplingHeapProfiler(uint64_t sample_interval = 512 * 1024,
     776             :                                  int stack_depth = 16,
     777             :                                  SamplingFlags flags = kSamplingNoFlags);
     778             : 
     779             :   /**
     780             :    * Stops the sampling heap profile and discards the current profile.
     781             :    */
     782             :   void StopSamplingHeapProfiler();
     783             : 
     784             :   /**
     785             :    * Returns the sampled profile of allocations allocated (and still live) since
     786             :    * StartSamplingHeapProfiler was called. The ownership of the pointer is
     787             :    * transfered to the caller. Returns nullptr if sampling heap profiler is not
     788             :    * active.
     789             :    */
     790             :   AllocationProfile* GetAllocationProfile();
     791             : 
     792             :   /**
     793             :    * Deletes all snapshots taken. All previously returned pointers to
     794             :    * snapshots and their contents become invalid after this call.
     795             :    */
     796             :   void DeleteAllHeapSnapshots();
     797             : 
     798             :   /** Binds a callback to embedder's class ID. */
     799             :   void SetWrapperClassInfoProvider(
     800             :       uint16_t class_id,
     801             :       WrapperInfoCallback callback);
     802             : 
     803             :   void SetGetRetainerInfosCallback(GetRetainerInfosCallback callback);
     804             : 
     805             :   /**
     806             :    * Default value of persistent handle class ID. Must not be used to
     807             :    * define a class. Can be used to reset a class of a persistent
     808             :    * handle.
     809             :    */
     810             :   static const uint16_t kPersistentHandleNoClassId = 0;
     811             : 
     812             :   /** Returns memory used for profiler internal data and snapshots. */
     813             :   size_t GetProfilerMemorySize();
     814             : 
     815             :  private:
     816             :   HeapProfiler();
     817             :   ~HeapProfiler();
     818             :   HeapProfiler(const HeapProfiler&);
     819             :   HeapProfiler& operator=(const HeapProfiler&);
     820             : };
     821             : 
     822             : /**
     823             :  * Interface for providing information about embedder's objects
     824             :  * held by global handles. This information is reported in two ways:
     825             :  *
     826             :  *  1. When calling AddObjectGroup, an embedder may pass
     827             :  *     RetainedObjectInfo instance describing the group.  To collect
     828             :  *     this information while taking a heap snapshot, V8 calls GC
     829             :  *     prologue and epilogue callbacks.
     830             :  *
     831             :  *  2. When a heap snapshot is collected, V8 additionally
     832             :  *     requests RetainedObjectInfos for persistent handles that
     833             :  *     were not previously reported via AddObjectGroup.
     834             :  *
     835             :  * Thus, if an embedder wants to provide information about native
     836             :  * objects for heap snapshots, it can do it in a GC prologue
     837             :  * handler, and / or by assigning wrapper class ids in the following way:
     838             :  *
     839             :  *  1. Bind a callback to class id by calling SetWrapperClassInfoProvider.
     840             :  *  2. Call SetWrapperClassId on certain persistent handles.
     841             :  *
     842             :  * V8 takes ownership of RetainedObjectInfo instances passed to it and
     843             :  * keeps them alive only during snapshot collection. Afterwards, they
     844             :  * are freed by calling the Dispose class function.
     845             :  */
     846             : class V8_EXPORT RetainedObjectInfo {  // NOLINT
     847             :  public:
     848             :   /** Called by V8 when it no longer needs an instance. */
     849             :   virtual void Dispose() = 0;
     850             : 
     851             :   /** Returns whether two instances are equivalent. */
     852             :   virtual bool IsEquivalent(RetainedObjectInfo* other) = 0;
     853             : 
     854             :   /**
     855             :    * Returns hash value for the instance. Equivalent instances
     856             :    * must have the same hash value.
     857             :    */
     858             :   virtual intptr_t GetHash() = 0;
     859             : 
     860             :   /**
     861             :    * Returns human-readable label. It must be a null-terminated UTF-8
     862             :    * encoded string. V8 copies its contents during a call to GetLabel.
     863             :    */
     864             :   virtual const char* GetLabel() = 0;
     865             : 
     866             :   /**
     867             :    * Returns human-readable group label. It must be a null-terminated UTF-8
     868             :    * encoded string. V8 copies its contents during a call to GetGroupLabel.
     869             :    * Heap snapshot generator will collect all the group names, create
     870             :    * top level entries with these names and attach the objects to the
     871             :    * corresponding top level group objects. There is a default
     872             :    * implementation which is required because embedders don't have their
     873             :    * own implementation yet.
     874             :    */
     875           0 :   virtual const char* GetGroupLabel() { return GetLabel(); }
     876             : 
     877             :   /**
     878             :    * Returns element count in case if a global handle retains
     879             :    * a subgraph by holding one of its nodes.
     880             :    */
     881           0 :   virtual intptr_t GetElementCount() { return -1; }
     882             : 
     883             :   /** Returns embedder's object size in bytes. */
     884           0 :   virtual intptr_t GetSizeInBytes() { return -1; }
     885             : 
     886             :  protected:
     887          12 :   RetainedObjectInfo() {}
     888          12 :   virtual ~RetainedObjectInfo() {}
     889             : 
     890             :  private:
     891             :   RetainedObjectInfo(const RetainedObjectInfo&);
     892             :   RetainedObjectInfo& operator=(const RetainedObjectInfo&);
     893             : };
     894             : 
     895             : 
     896             : /**
     897             :  * A struct for exporting HeapStats data from V8, using "push" model.
     898             :  * See HeapProfiler::GetHeapStats.
     899             :  */
     900             : struct HeapStatsUpdate {
     901             :   HeapStatsUpdate(uint32_t index, uint32_t count, uint32_t size)
     902          60 :     : index(index), count(count), size(size) { }
     903             :   uint32_t index;  // Index of the time interval that was changed.
     904             :   uint32_t count;  // New value of count field for the interval with this index.
     905             :   uint32_t size;  // New value of size field for the interval with this index.
     906             : };
     907             : 
     908             : 
     909             : }  // namespace v8
     910             : 
     911             : 
     912             : #endif  // V8_V8_PROFILER_H_

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