text: // Copyright 2010 the V8 project authors. All rights reserved.
  // Redistribution and use in source and binary forms, with or without
  // modification, are permitted provided that the following conditions are
  // met:
  //
  //     * Redistributions of source code must retain the above copyright
  //       notice, this list of conditions and the following disclaimer.
  //     * Redistributions in binary form must reproduce the above
  //       copyright notice, this list of conditions and the following
  //       disclaimer in the documentation and/or other materials provided
  //       with the distribution.
  //     * Neither the name of Google Inc. nor the names of its
  //       contributors may be used to endorse or promote products derived
  //       from this software without specific prior written permission.
  //
  // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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  // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  
  #ifndef V8_V8_PROFILER_H_
  #define V8_V8_PROFILER_H_
  
  #include "v8.h"
  
  #ifdef _WIN32
  // Setup for Windows DLL export/import. See v8.h in this directory for
  // information on how to build/use V8 as a DLL.
  #if defined(BUILDING_V8_SHARED) && defined(USING_V8_SHARED)
  #error both BUILDING_V8_SHARED and USING_V8_SHARED are set - please check the\
    build configuration to ensure that at most one of these is set
  #endif
  
  #ifdef BUILDING_V8_SHARED
  #define V8EXPORT __declspec(dllexport)
  #elif USING_V8_SHARED
  #define V8EXPORT __declspec(dllimport)
  #else
  #define V8EXPORT
  #endif
  
  #else  // _WIN32
  
  // Setup for Linux shared library export. See v8.h in this directory for
  // information on how to build/use V8 as shared library.
  #if defined(__GNUC__) && (__GNUC__ >= 4) && defined(V8_SHARED)
  #define V8EXPORT __attribute__ ((visibility("default")))
  #else  // defined(__GNUC__) && (__GNUC__ >= 4)
  #define V8EXPORT
  #endif  // defined(__GNUC__) && (__GNUC__ >= 4)
  
  #endif  // _WIN32
  
  
  /**
   * Profiler support for the V8 JavaScript engine.
   */
  namespace v8 {
  
  typedef uint32_t SnapshotObjectId;
  
  /**
   * CpuProfileNode represents a node in a call graph.
   */
  class V8EXPORT CpuProfileNode {
   public:
    /** Returns function name (empty string for anonymous functions.) */
    Handle<String> GetFunctionName() 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 total (self + children) execution time of the function,
     * in milliseconds, estimated by samples count.
     */
    double GetTotalTime() const;
  
    /**
     * Returns self execution time of the function, in milliseconds,
     * estimated by samples count.
     */
    double GetSelfTime() const;
  
    /** Returns the count of samples where function exists. */
    double GetTotalSamplesCount() const;
  
    /** Returns the count of samples where function was currently executing. */
    double GetSelfSamplesCount() const;
  
    /** Returns function entry UID. */
    unsigned GetCallUid() 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;
  };
  
  
  /**
   * CpuProfile contains a CPU profile in a form of two call trees:
   *  - top-down (from main() down to functions that do all the work);
   *  - bottom-up call graph (in backward direction).
   */
  class V8EXPORT 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 bottom up call tree. */
    const CpuProfileNode* GetBottomUpRoot() const;
  
    /** Returns the root node of the top down call tree. */
    const CpuProfileNode* GetTopDownRoot() 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.
   */
  class V8EXPORT CpuProfiler {
   public:
    /**
     * A note on security tokens usage. As scripts from different
     * origins can run inside a single V8 instance, it is possible to
     * have functions from different security contexts intermixed in a
     * single CPU profile. To avoid exposing function names belonging to
     * other contexts, filtering by security token is performed while
     * obtaining profiling results.
     */
  
    /**
     * Returns the number of profiles collected (doesn't include
     * profiles that are being collected at the moment of call.)
     */
    static int GetProfilesCount();
  
    /** Returns a profile by index. */
    static const CpuProfile* GetProfile(
        int index,
        Handle<Value> security_token = Handle<Value>());
  
    /** Returns a profile by uid. */
    static const CpuProfile* FindProfile(
        unsigned uid,
        Handle<Value> security_token = Handle<Value>());
  
    /**
     * 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.
     */
    static void StartProfiling(Handle<String> title);
  
    /**
     * Stops collecting CPU profile with a given title and returns it.
     * If the title given is empty, finishes the last profile started.
     */
    static const CpuProfile* StopProfiling(
        Handle<String> title,
        Handle<Value> security_token = Handle<Value>());
  
    /**
     * Deletes all existing profiles, also cancelling all profiling
     * activity.  All previously returned pointers to profiles and their
     * contents become invalid after this call.
     */
    static void DeleteAllProfiles();
  };
  
  
  class HeapGraphNode;
  
  
  /**
   * HeapSnapshotEdge represents a directed connection between heap
   * graph nodes: from retainers to retained nodes.
   */
  class V8EXPORT 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 V8EXPORT 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.
    };
  
    /** 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 node's retained size, in bytes. That is, self + sizes of
     * the objects that are reachable only from this object. In other
     * words, the size of memory that will be reclaimed having this node
     * collected.
     */
    int GetRetainedSize() const;
  
    /** Returns child nodes count of the node. */
    int GetChildrenCount() const;
  
    /** Retrieves a child by index. */
    const HeapGraphEdge* GetChild(int index) const;
  
    /** Returns retainer nodes count of the node. */
    int GetRetainersCount() const;
  
    /** Returns a retainer by index. */
    const HeapGraphEdge* GetRetainer(int index) const;
  
    /**
     * Returns a dominator node. This is the node that participates in every
     * path from the snapshot root to the current node.
     */
    const HeapGraphNode* GetDominatorNode() 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 V8EXPORT HeapSnapshot {
   public:
    enum Type {
      kFull = 0  // Heap snapshot with all instances and references.
    };
    enum SerializationFormat {
      kJSON = 0  // See format description near 'Serialize' method.
    };
  
    /** Returns heap snapshot type. */
    Type GetType() const;
  
    /** 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.
   */
  class V8EXPORT 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. */
    static int GetSnapshotsCount();
  
    /** Returns a snapshot by index. */
    static const HeapSnapshot* GetSnapshot(int index);
  
    /** Returns a profile by uid. */
    static const HeapSnapshot* FindSnapshot(unsigned uid);
  
    /**
     * Returns SnapshotObjectId for a heap object referenced by |value| if
     * it has been seen by the heap profiler, kUnknownObjectId otherwise.
     */
    static SnapshotObjectId GetSnapshotObjectId(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;
  
    /**
     * Takes a heap snapshot and returns it. Title may be an empty string.
     * See HeapSnapshot::Type for types description.
     */
    static const HeapSnapshot* TakeSnapshot(
        Handle<String> title,
        HeapSnapshot::Type type = HeapSnapshot::kFull,
        ActivityControl* control = NULL);
  
    /**
     * Starts tracking of heap objects population statistics. After calling
     * this method, all heap objects relocations done by the garbage collector
     * are being registered.
     */
    static void StartHeapObjectsTracking();
  
    /**
     * 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.
     *
     * StartHeapObjectsTracking must be called before the first call to this
     * method.
     */
    static SnapshotObjectId PushHeapObjectsStats(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.
     */
    static void StopHeapObjectsTracking();
  
    /**
     * Deletes all snapshots taken. All previously returned pointers to
     * snapshots and their contents become invalid after this call.
     */
    static void DeleteAllSnapshots();
  
    /** Binds a callback to embedder's class ID. */
    static void DefineWrapperClass(
        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 the number of currently existing persistent handles. */
    static int GetPersistentHandleCount();
  
    /** Returns memory used for profiler internal data and snapshots. */
    static size_t GetMemorySizeUsedByProfiler();
  };
  
  
  /**
   * 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 DefineWrapperClass.
   *  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 V8EXPORT 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::PushHeapObjectsStats.
   */
  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
  
  
  #undef V8EXPORT
  
  
  #endif  // V8_V8_PROFILER_H_
  