CSE2410 Fall 2014 Bounce

// Copyright 2010 the V8 project authors. All rights reserved.

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// modification, are permitted provided that the following conditions are

// met:

//

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#ifndef V8_V8_PROFILER_H_

#define V8_V8_PROFILER_H_

#include "v8.h"

/**

 * Profiler support for the V8 JavaScript engine.

 */

namespace v8 {

typedef uint32_t SnapshotObjectId;

/**

 * CpuProfileNode represents a node in a call graph.

 */

class V8_EXPORT CpuProfileNode {

 public:

  /** Returns function name (empty string for anonymous functions.) */

  Handle<String> GetFunctionName() const;

  /** Returns id of the script where function is located. */

  int GetScriptId() const;

  /** Returns resource name for script from where the function originates. */

  Handle<String> GetScriptResourceName() const;

  /**

   * Returns the number, 1-based, of the line where the function originates.

   * kNoLineNumberInfo if no line number information is available.

   */

  int GetLineNumber() const;

  /**

   * Returns 1-based number of the column where the function originates.

   * kNoColumnNumberInfo if no column number information is available.

   */

  int GetColumnNumber() const;

  /** Returns bailout reason for the function

    * if the optimization was disabled for it.

    */

  const char* GetBailoutReason() const;

  /**

    * Returns the count of samples where the function was currently executing.

    */

  unsigned GetHitCount() const;

  /** Returns function entry UID. */

  unsigned GetCallUid() const;

  /** Returns id of the node. The id is unique within the tree */

  unsigned GetNodeId() const;

  /** Returns child nodes count of the node. */

  int GetChildrenCount() const;

  /** Retrieves a child node by index. */

  const CpuProfileNode* GetChild(int index) const;

  static const int kNoLineNumberInfo = Message::kNoLineNumberInfo;

  static const int kNoColumnNumberInfo = Message::kNoColumnInfo;

};

/**

 * CpuProfile contains a CPU profile in a form of top-down call tree

 * (from main() down to functions that do all the work).

 */

class V8_EXPORT CpuProfile {

 public:

  /** Returns CPU profile UID (assigned by the profiler.) */

  unsigned GetUid() const;

  /** Returns CPU profile title. */

  Handle<String> GetTitle() const;

  /** Returns the root node of the top down call tree. */

  const CpuProfileNode* GetTopDownRoot() const;

  /**

    * Returns number of samples recorded. The samples are not recorded unless

    * |record_samples| parameter of CpuProfiler::StartCpuProfiling is true.

    */

  int GetSamplesCount() const;

  /**

    * Returns profile node corresponding to the top frame the sample at

    * the given index.

    */

  const CpuProfileNode* GetSample(int index) const;

  /**

    * Returns time when the profile recording started (in microseconds

    * since the Epoch).

    */

  int64_t GetStartTime() const;

  /**

    * Returns time when the profile recording was stopped (in microseconds

    * since the Epoch).

    */

  int64_t GetEndTime() const;

  /**

   * Deletes the profile and removes it from CpuProfiler's list.

   * All pointers to nodes previously returned become invalid.

   * Profiles with the same uid but obtained using different

   * security token are not deleted, but become inaccessible

   * using FindProfile method. It is embedder's responsibility

   * to call Delete on these profiles.

   */

  void Delete();

};

/**

 * Interface for controlling CPU profiling. Instance of the

 * profiler can be retrieved using v8::Isolate::GetCpuProfiler.

 */

class V8_EXPORT CpuProfiler {

 public:

  /**

   * Changes default CPU profiler sampling interval to the specified number

   * of microseconds. Default interval is 1000us. This method must be called

   * when there are no profiles being recorded.

   */

  void SetSamplingInterval(int us);

  /**

   * Returns the number of profiles collected (doesn't include

   * profiles that are being collected at the moment of call.)

   */

  int GetProfileCount();

  /** Returns a profile by index. */

  const CpuProfile* GetCpuProfile(int index);

  /**

   * Starts collecting CPU profile. Title may be an empty string. It

   * is allowed to have several profiles being collected at

   * once. Attempts to start collecting several profiles with the same

   * title are silently ignored. While collecting a profile, functions

   * from all security contexts are included in it. The token-based

   * filtering is only performed when querying for a profile.

   *

   * |record_samples| parameter controls whether individual samples should

   * be recorded in addition to the aggregated tree.

   */

  void StartCpuProfiling(Handle<String> title, bool record_samples = false);

  /**

   * Stops collecting CPU profile with a given title and returns it.

   * If the title given is empty, finishes the last profile started.

   */

  const CpuProfile* StopCpuProfiling(Handle<String> title);

  /**

   * Deletes all existing profiles, also cancelling all profiling

   * activity.  All previously returned pointers to profiles and their

   * contents become invalid after this call.

   */

  void DeleteAllCpuProfiles();

  /**

   * Tells the profiler whether the embedder is idle.

   */

  void SetIdle(bool is_idle);

 private:

  CpuProfiler();

  ~CpuProfiler();

  CpuProfiler(const CpuProfiler&);

  CpuProfiler& operator=(const CpuProfiler&);

};

class HeapGraphNode;

/**

 * HeapSnapshotEdge represents a directed connection between heap

 * graph nodes: from retainers to retained nodes.

 */

class V8_EXPORT HeapGraphEdge {

 public:

  enum Type {

    kContextVariable = 0,  // A variable from a function context.

    kElement = 1,          // An element of an array.

    kProperty = 2,         // A named object property.

    kInternal = 3,         // A link that can't be accessed from JS,

                           // thus, its name isn't a real property name

                           // (e.g. parts of a ConsString).

    kHidden = 4,           // A link that is needed for proper sizes

                           // calculation, but may be hidden from user.

    kShortcut = 5,         // A link that must not be followed during

                           // sizes calculation.

    kWeak = 6              // A weak reference (ignored by the GC).

  };

  /** Returns edge type (see HeapGraphEdge::Type). */

  Type GetType() const;

  /**

   * Returns edge name. This can be a variable name, an element index, or

   * a property name.

   */

  Handle<Value> GetName() const;

  /** Returns origin node. */

  const HeapGraphNode* GetFromNode() const;

  /** Returns destination node. */

  const HeapGraphNode* GetToNode() const;

};

/**

 * HeapGraphNode represents a node in a heap graph.

 */

class V8_EXPORT HeapGraphNode {

 public:

  enum Type {

    kHidden = 0,        // Hidden node, may be filtered when shown to user.

    kArray = 1,         // An array of elements.

    kString = 2,        // A string.

    kObject = 3,        // A JS object (except for arrays and strings).

    kCode = 4,          // Compiled code.

    kClosure = 5,       // Function closure.

    kRegExp = 6,        // RegExp.

    kHeapNumber = 7,    // Number stored in the heap.

    kNative = 8,        // Native object (not from V8 heap).

    kSynthetic = 9,     // Synthetic object, usualy used for grouping

                        // snapshot items together.

    kConsString = 10,   // Concatenated string. A pair of pointers to strings.

    kSlicedString = 11  // Sliced string. A fragment of another string.

  };

  /** Returns node type (see HeapGraphNode::Type). */

  Type GetType() const;

  /**

   * Returns node name. Depending on node's type this can be the name

   * of the constructor (for objects), the name of the function (for

   * closures), string value, or an empty string (for compiled code).

   */

  Handle<String> GetName() const;

  /**

   * Returns node id. For the same heap object, the id remains the same

   * across all snapshots.

   */

  SnapshotObjectId GetId() const;

  /** Returns node's own size, in bytes. */

  int GetSelfSize() const;

  /** Returns child nodes count of the node. */

  int GetChildrenCount() const;

  /** Retrieves a child by index. */

  const HeapGraphEdge* GetChild(int index) const;

  /**

   * Finds and returns a value from the heap corresponding to this node,

   * if the value is still reachable.

   */

  Handle<Value> GetHeapValue() const;

};

/**

 * HeapSnapshots record the state of the JS heap at some moment.

 */

class V8_EXPORT HeapSnapshot {

 public:

  enum SerializationFormat {

    kJSON = 0  // See format description near 'Serialize' method.

  };

  /** Returns heap snapshot UID (assigned by the profiler.) */

  unsigned GetUid() const;

  /** Returns heap snapshot title. */

  Handle<String> GetTitle() const;

  /** Returns the root node of the heap graph. */

  const HeapGraphNode* GetRoot() const;

  /** Returns a node by its id. */

  const HeapGraphNode* GetNodeById(SnapshotObjectId id) const;

  /** Returns total nodes count in the snapshot. */

  int GetNodesCount() const;

  /** Returns a node by index. */

  const HeapGraphNode* GetNode(int index) const;

  /** Returns a max seen JS object Id. */

  SnapshotObjectId GetMaxSnapshotJSObjectId() const;

  /**

   * Deletes the snapshot and removes it from HeapProfiler's list.

   * All pointers to nodes, edges and paths previously returned become

   * invalid.

   */

  void Delete();

  /**

   * Prepare a serialized representation of the snapshot. The result

   * is written into the stream provided in chunks of specified size.

   * The total length of the serialized snapshot is unknown in

   * advance, it can be roughly equal to JS heap size (that means,

   * it can be really big - tens of megabytes).

   *

   * For the JSON format, heap contents are represented as an object

   * with the following structure:

   *

   *  {

   *    snapshot: {

   *      title: "...",

   *      uid: nnn,

   *      meta: { meta-info },

   *      node_count: nnn,

   *      edge_count: nnn

   *    },

   *    nodes: [nodes array],

   *    edges: [edges array],

   *    strings: [strings array]

   *  }

   *

   * Nodes reference strings, other nodes, and edges by their indexes

   * in corresponding arrays.

   */

  void Serialize(OutputStream* stream, SerializationFormat format) const;

};

class RetainedObjectInfo;

/**

 * Interface for controlling heap profiling. Instance of the

 * profiler can be retrieved using v8::Isolate::GetHeapProfiler.

 */

class V8_EXPORT HeapProfiler {

 public:

  /**

   * Callback function invoked for obtaining RetainedObjectInfo for

   * the given JavaScript wrapper object. It is prohibited to enter V8

   * while the callback is running: only getters on the handle and

   * GetPointerFromInternalField on the objects are allowed.

   */

  typedef RetainedObjectInfo* (*WrapperInfoCallback)

      (uint16_t class_id, Handle<Value> wrapper);

  /** Returns the number of snapshots taken. */

  int GetSnapshotCount();

  /** Returns a snapshot by index. */

  const HeapSnapshot* GetHeapSnapshot(int index);

  /**

   * Returns SnapshotObjectId for a heap object referenced by |value| if

   * it has been seen by the heap profiler, kUnknownObjectId otherwise.

   */

  SnapshotObjectId GetObjectId(Handle<Value> value);

  /**

   * A constant for invalid SnapshotObjectId. GetSnapshotObjectId will return

   * it in case heap profiler cannot find id  for the object passed as

   * parameter. HeapSnapshot::GetNodeById will always return NULL for such id.

   */

  static const SnapshotObjectId kUnknownObjectId = 0;

  /**

   * Callback interface for retrieving user friendly names of global objects.

   */

  class ObjectNameResolver {

   public:

    /**

     * Returns name to be used in the heap snapshot for given node. Returned

     * string must stay alive until snapshot collection is completed.

     */

    virtual const char* GetName(Handle<Object> object) = 0;

   protected:

    virtual ~ObjectNameResolver() {}

  };

  /**

   * Takes a heap snapshot and returns it. Title may be an empty string.

   */

  const HeapSnapshot* TakeHeapSnapshot(

      Handle<String> title,

      ActivityControl* control = NULL,

      ObjectNameResolver* global_object_name_resolver = NULL);

  /**

   * Starts tracking of heap objects population statistics. After calling

   * this method, all heap objects relocations done by the garbage collector

   * are being registered.

   */

  void StartTrackingHeapObjects();

  /**

   * Adds a new time interval entry to the aggregated statistics array. The

   * time interval entry contains information on the current heap objects

   * population size. The method also updates aggregated statistics and

   * reports updates for all previous time intervals via the OutputStream

   * object. Updates on each time interval are provided as a stream of the

   * HeapStatsUpdate structure instances.

   * The return value of the function is the last seen heap object Id.

   *

   * StartTrackingHeapObjects must be called before the first call to this

   * method.

   */

  SnapshotObjectId GetHeapStats(OutputStream* stream);

  /**

   * Stops tracking of heap objects population statistics, cleans up all

   * collected data. StartHeapObjectsTracking must be called again prior to

   * calling PushHeapObjectsStats next time.

   */

  void StopTrackingHeapObjects();

  /**

   * Deletes all snapshots taken. All previously returned pointers to

   * snapshots and their contents become invalid after this call.

   */

  void DeleteAllHeapSnapshots();

  /** Binds a callback to embedder's class ID. */

  void SetWrapperClassInfoProvider(

      uint16_t class_id,

      WrapperInfoCallback callback);

  /**

   * Default value of persistent handle class ID. Must not be used to

   * define a class. Can be used to reset a class of a persistent

   * handle.

   */

  static const uint16_t kPersistentHandleNoClassId = 0;

  /** Returns memory used for profiler internal data and snapshots. */

  size_t GetProfilerMemorySize();

  /**

   * Sets a RetainedObjectInfo for an object group (see V8::SetObjectGroupId).

   */

  void SetRetainedObjectInfo(UniqueId id, RetainedObjectInfo* info);

  /**

   * Starts recording JS allocations immediately as they arrive and tracking of

   * heap objects population statistics.

   */

  void StartRecordingHeapAllocations();

  /**

   * Stops recording JS allocations and tracking of heap objects population

   * statistics, cleans all collected heap objects population statistics data.

   */

  void StopRecordingHeapAllocations();

 private:

  HeapProfiler();

  ~HeapProfiler();

  HeapProfiler(const HeapProfiler&);

  HeapProfiler& operator=(const HeapProfiler&);

};

/**

 * Interface for providing information about embedder's objects

 * held by global handles. This information is reported in two ways:

 *

 *  1. When calling AddObjectGroup, an embedder may pass

 *     RetainedObjectInfo instance describing the group.  To collect

 *     this information while taking a heap snapshot, V8 calls GC

 *     prologue and epilogue callbacks.

 *

 *  2. When a heap snapshot is collected, V8 additionally

 *     requests RetainedObjectInfos for persistent handles that

 *     were not previously reported via AddObjectGroup.

 *

 * Thus, if an embedder wants to provide information about native

 * objects for heap snapshots, he can do it in a GC prologue

 * handler, and / or by assigning wrapper class ids in the following way:

 *

 *  1. Bind a callback to class id by calling SetWrapperClassInfoProvider.

 *  2. Call SetWrapperClassId on certain persistent handles.

 *

 * V8 takes ownership of RetainedObjectInfo instances passed to it and

 * keeps them alive only during snapshot collection. Afterwards, they

 * are freed by calling the Dispose class function.

 */

class V8_EXPORT RetainedObjectInfo {  // NOLINT

 public:

  /** Called by V8 when it no longer needs an instance. */

  virtual void Dispose() = 0;

  /** Returns whether two instances are equivalent. */

  virtual bool IsEquivalent(RetainedObjectInfo* other) = 0;

  /**

   * Returns hash value for the instance. Equivalent instances

   * must have the same hash value.

   */

  virtual intptr_t GetHash() = 0;

  /**

   * Returns human-readable label. It must be a null-terminated UTF-8

   * encoded string. V8 copies its contents during a call to GetLabel.

   */

  virtual const char* GetLabel() = 0;

  /**

   * Returns human-readable group label. It must be a null-terminated UTF-8

   * encoded string. V8 copies its contents during a call to GetGroupLabel.

   * Heap snapshot generator will collect all the group names, create

   * top level entries with these names and attach the objects to the

   * corresponding top level group objects. There is a default

   * implementation which is required because embedders don't have their

   * own implementation yet.

   */

  virtual const char* GetGroupLabel() { return GetLabel(); }

  /**

   * Returns element count in case if a global handle retains

   * a subgraph by holding one of its nodes.

   */

  virtual intptr_t GetElementCount() { return -1; }

  /** Returns embedder's object size in bytes. */

  virtual intptr_t GetSizeInBytes() { return -1; }

 protected:

  RetainedObjectInfo() {}

  virtual ~RetainedObjectInfo() {}

 private:

  RetainedObjectInfo(const RetainedObjectInfo&);

  RetainedObjectInfo& operator=(const RetainedObjectInfo&);

};

/**

 * A struct for exporting HeapStats data from V8, using "push" model.

 * See HeapProfiler::GetHeapStats.

 */

struct HeapStatsUpdate {

  HeapStatsUpdate(uint32_t index, uint32_t count, uint32_t size)

    : index(index), count(count), size(size) { }

  uint32_t index;  // Index of the time interval that was changed.

  uint32_t count;  // New value of count field for the interval with this index.

  uint32_t size;  // New value of size field for the interval with this index.

};

}  // namespace v8

#endif  // V8_V8_PROFILER_H_