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- // Copyright 2010 the V8 project authors. All rights reserved.
- // Use of this source code is governed by a BSD-style license that can be
- // found in the LICENSE file.
- #ifndef V8_V8_PROFILER_H_
- #define V8_V8_PROFILER_H_
- #include <limits.h>
- #include <memory>
- #include <unordered_set>
- #include <vector>
- #include "v8-local-handle.h" // NOLINT(build/include_directory)
- #include "v8-message.h" // NOLINT(build/include_directory)
- #include "v8-persistent-handle.h" // NOLINT(build/include_directory)
- /**
- * Profiler support for the V8 JavaScript engine.
- */
- namespace v8 {
- enum class EmbedderStateTag : uint8_t;
- class HeapGraphNode;
- struct HeapStatsUpdate;
- class Object;
- enum StateTag : int;
- using NativeObject = void*;
- using SnapshotObjectId = uint32_t;
- using ProfilerId = uint32_t;
- struct CpuProfileDeoptFrame {
- int script_id;
- size_t position;
- };
- namespace internal {
- class CpuProfile;
- } // namespace internal
- } // namespace v8
- #ifdef V8_OS_WIN
- template class V8_EXPORT std::vector<v8::CpuProfileDeoptFrame>;
- #endif
- namespace v8 {
- struct V8_EXPORT CpuProfileDeoptInfo {
- /** A pointer to a static string owned by v8. */
- const char* deopt_reason;
- std::vector<CpuProfileDeoptFrame> stack;
- };
- } // namespace v8
- #ifdef V8_OS_WIN
- template class V8_EXPORT std::vector<v8::CpuProfileDeoptInfo>;
- #endif
- namespace v8 {
- /**
- * CpuProfileNode represents a node in a call graph.
- */
- class V8_EXPORT CpuProfileNode {
- public:
- struct LineTick {
- /** The 1-based number of the source line where the function originates. */
- int line;
- /** The count of samples associated with the source line. */
- unsigned int hit_count;
- };
- // An annotation hinting at the source of a CpuProfileNode.
- enum SourceType {
- // User-supplied script with associated resource information.
- kScript = 0,
- // Native scripts and provided builtins.
- kBuiltin = 1,
- // Callbacks into native code.
- kCallback = 2,
- // VM-internal functions or state.
- kInternal = 3,
- // A node that failed to symbolize.
- kUnresolved = 4,
- };
- /** Returns function name (empty string for anonymous functions.) */
- Local<String> GetFunctionName() const;
- /**
- * Returns function name (empty string for anonymous functions.)
- * The string ownership is *not* passed to the caller. It stays valid until
- * profile is deleted. The function is thread safe.
- */
- const char* GetFunctionNameStr() const;
- /** Returns id of the script where function is located. */
- int GetScriptId() const;
- /** Returns resource name for script from where the function originates. */
- Local<String> GetScriptResourceName() const;
- /**
- * Returns resource name for script from where the function originates.
- * The string ownership is *not* passed to the caller. It stays valid until
- * profile is deleted. The function is thread safe.
- */
- const char* GetScriptResourceNameStr() const;
- /**
- * Return true if the script from where the function originates is flagged as
- * being shared cross-origin.
- */
- bool IsScriptSharedCrossOrigin() 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 the number of the function's source lines that collect the samples.
- */
- unsigned int GetHitLineCount() const;
- /** Returns the set of source lines that collect the samples.
- * The caller allocates buffer and responsible for releasing it.
- * True if all available entries are copied, otherwise false.
- * The function copies nothing if buffer is not large enough.
- */
- bool GetLineTicks(LineTick* entries, unsigned int length) 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 id of the node. The id is unique within the tree */
- unsigned GetNodeId() const;
- /**
- * Gets the type of the source which the node was captured from.
- */
- SourceType GetSourceType() const;
- /** Returns child nodes count of the node. */
- int GetChildrenCount() const;
- /** Retrieves a child node by index. */
- const CpuProfileNode* GetChild(int index) const;
- /** Retrieves the ancestor node, or null if the root. */
- const CpuProfileNode* GetParent() const;
- /** Retrieves deopt infos for the node. */
- const std::vector<CpuProfileDeoptInfo>& GetDeoptInfos() 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 title. */
- Local<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 the timestamp of the sample. The timestamp is the number of
- * microseconds since some unspecified starting point.
- * The point is equal to the starting point used by GetStartTime.
- */
- int64_t GetSampleTimestamp(int index) const;
- /**
- * Returns time when the profile recording was started (in microseconds)
- * since some unspecified starting point.
- */
- int64_t GetStartTime() const;
- /**
- * Returns state of the vm when sample was captured.
- */
- StateTag GetSampleState(int index) const;
- /**
- * Returns state of the embedder when sample was captured.
- */
- EmbedderStateTag GetSampleEmbedderState(int index) const;
- /**
- * Returns time when the profile recording was stopped (in microseconds)
- * since some unspecified starting point.
- * The point is equal to the starting point used by GetStartTime.
- */
- int64_t GetEndTime() const;
- /**
- * Deletes the profile and removes it from CpuProfiler's list.
- * All pointers to nodes previously returned become invalid.
- */
- void Delete();
- };
- enum CpuProfilingMode {
- // In the resulting CpuProfile tree, intermediate nodes in a stack trace
- // (from the root to a leaf) will have line numbers that point to the start
- // line of the function, rather than the line of the callsite of the child.
- kLeafNodeLineNumbers,
- // In the resulting CpuProfile tree, nodes are separated based on the line
- // number of their callsite in their parent.
- kCallerLineNumbers,
- };
- // Determines how names are derived for functions sampled.
- enum CpuProfilingNamingMode {
- // Use the immediate name of functions at compilation time.
- kStandardNaming,
- // Use more verbose naming for functions without names, inferred from scope
- // where possible.
- kDebugNaming,
- };
- enum CpuProfilingLoggingMode {
- // Enables logging when a profile is active, and disables logging when all
- // profiles are detached.
- kLazyLogging,
- // Enables logging for the lifetime of the CpuProfiler. Calls to
- // StartRecording are faster, at the expense of runtime overhead.
- kEagerLogging,
- };
- // Enum for returning profiling status. Once StartProfiling is called,
- // we want to return to clients whether the profiling was able to start
- // correctly, or return a descriptive error.
- enum class CpuProfilingStatus {
- kStarted,
- kAlreadyStarted,
- kErrorTooManyProfilers
- };
- /**
- * Result from StartProfiling returning the Profiling Status, and
- * id of the started profiler, or 0 if profiler is not started
- */
- struct CpuProfilingResult {
- const ProfilerId id;
- const CpuProfilingStatus status;
- };
- /**
- * Delegate for when max samples reached and samples are discarded.
- */
- class V8_EXPORT DiscardedSamplesDelegate {
- public:
- DiscardedSamplesDelegate() = default;
- virtual ~DiscardedSamplesDelegate() = default;
- virtual void Notify() = 0;
- ProfilerId GetId() const { return profiler_id_; }
- private:
- friend internal::CpuProfile;
- void SetId(ProfilerId id) { profiler_id_ = id; }
- ProfilerId profiler_id_;
- };
- /**
- * Optional profiling attributes.
- */
- class V8_EXPORT CpuProfilingOptions {
- public:
- // Indicates that the sample buffer size should not be explicitly limited.
- static const unsigned kNoSampleLimit = UINT_MAX;
- /**
- * \param mode Type of computation of stack frame line numbers.
- * \param max_samples The maximum number of samples that should be recorded by
- * the profiler. Samples obtained after this limit will be
- * discarded.
- * \param sampling_interval_us controls the profile-specific target
- * sampling interval. The provided sampling
- * interval will be snapped to the next lowest
- * non-zero multiple of the profiler's sampling
- * interval, set via SetSamplingInterval(). If
- * zero, the sampling interval will be equal to
- * the profiler's sampling interval.
- * \param filter_context If specified, profiles will only contain frames
- * using this context. Other frames will be elided.
- */
- CpuProfilingOptions(
- CpuProfilingMode mode = kLeafNodeLineNumbers,
- unsigned max_samples = kNoSampleLimit, int sampling_interval_us = 0,
- MaybeLocal<Context> filter_context = MaybeLocal<Context>());
- CpuProfilingMode mode() const { return mode_; }
- unsigned max_samples() const { return max_samples_; }
- int sampling_interval_us() const { return sampling_interval_us_; }
- private:
- friend class internal::CpuProfile;
- bool has_filter_context() const { return !filter_context_.IsEmpty(); }
- void* raw_filter_context() const;
- CpuProfilingMode mode_;
- unsigned max_samples_;
- int sampling_interval_us_;
- CopyablePersistentTraits<Context>::CopyablePersistent filter_context_;
- };
- /**
- * Interface for controlling CPU profiling. Instance of the
- * profiler can be created using v8::CpuProfiler::New method.
- */
- class V8_EXPORT CpuProfiler {
- public:
- /**
- * Creates a new CPU profiler for the |isolate|. The isolate must be
- * initialized. The profiler object must be disposed after use by calling
- * |Dispose| method.
- */
- static CpuProfiler* New(Isolate* isolate,
- CpuProfilingNamingMode = kDebugNaming,
- CpuProfilingLoggingMode = kLazyLogging);
- /**
- * Synchronously collect current stack sample in all profilers attached to
- * the |isolate|. The call does not affect number of ticks recorded for
- * the current top node.
- */
- static void CollectSample(Isolate* isolate);
- /**
- * Disposes the CPU profiler object.
- */
- void Dispose();
- /**
- * 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);
- /**
- * Sets whether or not the profiler should prioritize consistency of sample
- * periodicity on Windows. Disabling this can greatly reduce CPU usage, but
- * may result in greater variance in sample timings from the platform's
- * scheduler. Defaults to enabled. This method must be called when there are
- * no profiles being recorded.
- */
- void SetUsePreciseSampling(bool);
- /**
- * Starts collecting a CPU profile. Several profiles may be collected at once.
- * Generates an anonymous profiler, without a String identifier.
- */
- CpuProfilingResult Start(
- CpuProfilingOptions options,
- std::unique_ptr<DiscardedSamplesDelegate> delegate = nullptr);
- /**
- * Starts collecting a CPU profile. Title may be an empty string. Several
- * profiles may be collected at once. Attempts to start collecting several
- * profiles with the same title are silently ignored.
- */
- CpuProfilingResult Start(
- Local<String> title, CpuProfilingOptions options,
- std::unique_ptr<DiscardedSamplesDelegate> delegate = nullptr);
- /**
- * Starts profiling with the same semantics as above, except with expanded
- * parameters.
- *
- * |record_samples| parameter controls whether individual samples should
- * be recorded in addition to the aggregated tree.
- *
- * |max_samples| controls the maximum number of samples that should be
- * recorded by the profiler. Samples obtained after this limit will be
- * discarded.
- */
- CpuProfilingResult Start(
- Local<String> title, CpuProfilingMode mode, bool record_samples = false,
- unsigned max_samples = CpuProfilingOptions::kNoSampleLimit);
- /**
- * The same as StartProfiling above, but the CpuProfilingMode defaults to
- * kLeafNodeLineNumbers mode, which was the previous default behavior of the
- * profiler.
- */
- CpuProfilingResult Start(Local<String> title, bool record_samples = false);
- /**
- * Starts collecting a CPU profile. Title may be an empty string. Several
- * profiles may be collected at once. Attempts to start collecting several
- * profiles with the same title are silently ignored.
- */
- CpuProfilingStatus StartProfiling(
- Local<String> title, CpuProfilingOptions options,
- std::unique_ptr<DiscardedSamplesDelegate> delegate = nullptr);
- /**
- * Starts profiling with the same semantics as above, except with expanded
- * parameters.
- *
- * |record_samples| parameter controls whether individual samples should
- * be recorded in addition to the aggregated tree.
- *
- * |max_samples| controls the maximum number of samples that should be
- * recorded by the profiler. Samples obtained after this limit will be
- * discarded.
- */
- CpuProfilingStatus StartProfiling(
- Local<String> title, CpuProfilingMode mode, bool record_samples = false,
- unsigned max_samples = CpuProfilingOptions::kNoSampleLimit);
- /**
- * The same as StartProfiling above, but the CpuProfilingMode defaults to
- * kLeafNodeLineNumbers mode, which was the previous default behavior of the
- * profiler.
- */
- CpuProfilingStatus StartProfiling(Local<String> title,
- bool record_samples = false);
- /**
- * Stops collecting CPU profile with a given id and returns it.
- */
- CpuProfile* Stop(ProfilerId id);
- /**
- * Stops collecting CPU profile with a given title and returns it.
- * If the title given is empty, finishes the last profile started.
- */
- CpuProfile* StopProfiling(Local<String> title);
- /**
- * Generate more detailed source positions to code objects. This results in
- * better results when mapping profiling samples to script source.
- */
- static void UseDetailedSourcePositionsForProfiling(Isolate* isolate);
- private:
- CpuProfiler();
- ~CpuProfiler();
- CpuProfiler(const CpuProfiler&);
- CpuProfiler& operator=(const CpuProfiler&);
- };
- /**
- * 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.
- */
- Local<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, usually 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.
- kSymbol = 12, // A Symbol (ES6).
- kBigInt = 13 // BigInt.
- };
- /** 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).
- */
- Local<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. */
- size_t GetShallowSize() const;
- /** Returns child nodes count of the node. */
- int GetChildrenCount() const;
- /** Retrieves a child by index. */
- const HeapGraphEdge* GetChild(int index) const;
- };
- /**
- * An interface for exporting data from V8, using "push" model.
- */
- class V8_EXPORT OutputStream {
- public:
- enum WriteResult {
- kContinue = 0,
- kAbort = 1
- };
- virtual ~OutputStream() = default;
- /** Notify about the end of stream. */
- virtual void EndOfStream() = 0;
- /** Get preferred output chunk size. Called only once. */
- virtual int GetChunkSize() { return 1024; }
- /**
- * Writes the next chunk of snapshot data into the stream. Writing
- * can be stopped by returning kAbort as function result. EndOfStream
- * will not be called in case writing was aborted.
- */
- virtual WriteResult WriteAsciiChunk(char* data, int size) = 0;
- /**
- * Writes the next chunk of heap stats data into the stream. Writing
- * can be stopped by returning kAbort as function result. EndOfStream
- * will not be called in case writing was aborted.
- */
- virtual WriteResult WriteHeapStatsChunk(HeapStatsUpdate* data, int count) {
- return kAbort;
- }
- };
- /**
- * 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 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 = kJSON) const;
- };
- /**
- * An interface for reporting progress and controlling long-running
- * activities.
- */
- class V8_EXPORT ActivityControl {
- public:
- enum ControlOption {
- kContinue = 0,
- kAbort = 1
- };
- virtual ~ActivityControl() = default;
- /**
- * Notify about current progress. The activity can be stopped by
- * returning kAbort as the callback result.
- */
- virtual ControlOption ReportProgressValue(uint32_t done, uint32_t total) = 0;
- };
- /**
- * AllocationProfile is a sampled profile of allocations done by the program.
- * This is structured as a call-graph.
- */
- class V8_EXPORT AllocationProfile {
- public:
- struct Allocation {
- /**
- * Size of the sampled allocation object.
- */
- size_t size;
- /**
- * The number of objects of such size that were sampled.
- */
- unsigned int count;
- };
- /**
- * Represents a node in the call-graph.
- */
- struct Node {
- /**
- * Name of the function. May be empty for anonymous functions or if the
- * script corresponding to this function has been unloaded.
- */
- Local<String> name;
- /**
- * Name of the script containing the function. May be empty if the script
- * name is not available, or if the script has been unloaded.
- */
- Local<String> script_name;
- /**
- * id of the script where the function is located. May be equal to
- * v8::UnboundScript::kNoScriptId in cases where the script doesn't exist.
- */
- int script_id;
- /**
- * Start position of the function in the script.
- */
- int start_position;
- /**
- * 1-indexed line number where the function starts. May be
- * kNoLineNumberInfo if no line number information is available.
- */
- int line_number;
- /**
- * 1-indexed column number where the function starts. May be
- * kNoColumnNumberInfo if no line number information is available.
- */
- int column_number;
- /**
- * Unique id of the node.
- */
- uint32_t node_id;
- /**
- * List of callees called from this node for which we have sampled
- * allocations. The lifetime of the children is scoped to the containing
- * AllocationProfile.
- */
- std::vector<Node*> children;
- /**
- * List of self allocations done by this node in the call-graph.
- */
- std::vector<Allocation> allocations;
- };
- /**
- * Represent a single sample recorded for an allocation.
- */
- struct Sample {
- /**
- * id of the node in the profile tree.
- */
- uint32_t node_id;
- /**
- * Size of the sampled allocation object.
- */
- size_t size;
- /**
- * The number of objects of such size that were sampled.
- */
- unsigned int count;
- /**
- * Unique time-ordered id of the allocation sample. Can be used to track
- * what samples were added or removed between two snapshots.
- */
- uint64_t sample_id;
- };
- /**
- * Returns the root node of the call-graph. The root node corresponds to an
- * empty JS call-stack. The lifetime of the returned Node* is scoped to the
- * containing AllocationProfile.
- */
- virtual Node* GetRootNode() = 0;
- virtual const std::vector<Sample>& GetSamples() = 0;
- virtual ~AllocationProfile() = default;
- static const int kNoLineNumberInfo = Message::kNoLineNumberInfo;
- static const int kNoColumnNumberInfo = Message::kNoColumnInfo;
- };
- /**
- * An object graph consisting of embedder objects and V8 objects.
- * Edges of the graph are strong references between the objects.
- * The embedder can build this graph during heap snapshot generation
- * to include the embedder objects in the heap snapshot.
- * Usage:
- * 1) Define derived class of EmbedderGraph::Node for embedder objects.
- * 2) Set the build embedder graph callback on the heap profiler using
- * HeapProfiler::AddBuildEmbedderGraphCallback.
- * 3) In the callback use graph->AddEdge(node1, node2) to add an edge from
- * node1 to node2.
- * 4) To represent references from/to V8 object, construct V8 nodes using
- * graph->V8Node(value).
- */
- class V8_EXPORT EmbedderGraph {
- public:
- class Node {
- public:
- /**
- * Detachedness specifies whether an object is attached or detached from the
- * main application state. While unkown in general, there may be objects
- * that specifically know their state. V8 passes this information along in
- * the snapshot. Users of the snapshot may use it to annotate the object
- * graph.
- */
- enum class Detachedness : uint8_t {
- kUnknown = 0,
- kAttached = 1,
- kDetached = 2,
- };
- Node() = default;
- virtual ~Node() = default;
- virtual const char* Name() = 0;
- virtual size_t SizeInBytes() = 0;
- /**
- * The corresponding V8 wrapper node if not null.
- * During heap snapshot generation the embedder node and the V8 wrapper
- * node will be merged into one node to simplify retaining paths.
- */
- virtual Node* WrapperNode() { return nullptr; }
- virtual bool IsRootNode() { return false; }
- /** Must return true for non-V8 nodes. */
- virtual bool IsEmbedderNode() { return true; }
- /**
- * Optional name prefix. It is used in Chrome for tagging detached nodes.
- */
- virtual const char* NamePrefix() { return nullptr; }
- /**
- * Returns the NativeObject that can be used for querying the
- * |HeapSnapshot|.
- */
- virtual NativeObject GetNativeObject() { return nullptr; }
- /**
- * Detachedness state of a given object. While unkown in general, there may
- * be objects that specifically know their state. V8 passes this information
- * along in the snapshot. Users of the snapshot may use it to annotate the
- * object graph.
- */
- virtual Detachedness GetDetachedness() { return Detachedness::kUnknown; }
- Node(const Node&) = delete;
- Node& operator=(const Node&) = delete;
- };
- /**
- * Returns a node corresponding to the given V8 value. Ownership is not
- * transferred. The result pointer is valid while the graph is alive.
- */
- virtual Node* V8Node(const v8::Local<v8::Value>& value) = 0;
- /**
- * Adds the given node to the graph and takes ownership of the node.
- * Returns a raw pointer to the node that is valid while the graph is alive.
- */
- virtual Node* AddNode(std::unique_ptr<Node> node) = 0;
- /**
- * Adds an edge that represents a strong reference from the given
- * node |from| to the given node |to|. The nodes must be added to the graph
- * before calling this function.
- *
- * If name is nullptr, the edge will have auto-increment indexes, otherwise
- * it will be named accordingly.
- */
- virtual void AddEdge(Node* from, Node* to, const char* name = nullptr) = 0;
- virtual ~EmbedderGraph() = default;
- };
- /**
- * Interface for controlling heap profiling. Instance of the
- * profiler can be retrieved using v8::Isolate::GetHeapProfiler.
- */
- class V8_EXPORT HeapProfiler {
- public:
- enum SamplingFlags {
- kSamplingNoFlags = 0,
- kSamplingForceGC = 1 << 0,
- };
- /**
- * Callback function invoked during heap snapshot generation to retrieve
- * the embedder object graph. The callback should use graph->AddEdge(..) to
- * add references between the objects.
- * The callback must not trigger garbage collection in V8.
- */
- typedef void (*BuildEmbedderGraphCallback)(v8::Isolate* isolate,
- v8::EmbedderGraph* graph,
- void* data);
- /**
- * Callback function invoked during heap snapshot generation to retrieve
- * the detachedness state of an object referenced by a TracedReference.
- *
- * The callback takes Local<Value> as parameter to allow the embedder to
- * unpack the TracedReference into a Local and reuse that Local for different
- * purposes.
- */
- using GetDetachednessCallback = EmbedderGraph::Node::Detachedness (*)(
- v8::Isolate* isolate, const v8::Local<v8::Value>& v8_value,
- uint16_t class_id, void* data);
- /** 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(Local<Value> value);
- /**
- * Returns SnapshotObjectId for a native object referenced by |value| if it
- * has been seen by the heap profiler, kUnknownObjectId otherwise.
- */
- SnapshotObjectId GetObjectId(NativeObject value);
- /**
- * Returns heap object with given SnapshotObjectId if the object is alive,
- * otherwise empty handle is returned.
- */
- Local<Value> FindObjectById(SnapshotObjectId id);
- /**
- * Clears internal map from SnapshotObjectId to heap object. The new objects
- * will not be added into it unless a heap snapshot is taken or heap object
- * tracking is kicked off.
- */
- void ClearObjectIds();
- /**
- * 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(Local<Object> object) = 0;
- protected:
- virtual ~ObjectNameResolver() = default;
- };
- /**
- * Takes a heap snapshot and returns it.
- */
- const HeapSnapshot* TakeHeapSnapshot(
- ActivityControl* control = nullptr,
- ObjectNameResolver* global_object_name_resolver = nullptr,
- bool treat_global_objects_as_roots = true,
- bool capture_numeric_value = false);
- /**
- * Starts tracking of heap objects population statistics. After calling
- * this method, all heap objects relocations done by the garbage collector
- * are being registered.
- *
- * |track_allocations| parameter controls whether stack trace of each
- * allocation in the heap will be recorded and reported as part of
- * HeapSnapshot.
- */
- void StartTrackingHeapObjects(bool track_allocations = false);
- /**
- * 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.
- * If |timestamp_us| is supplied, timestamp of the new entry will be written
- * into it. 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,
- int64_t* timestamp_us = nullptr);
- /**
- * Stops tracking of heap objects population statistics, cleans up all
- * collected data. StartHeapObjectsTracking must be called again prior to
- * calling GetHeapStats next time.
- */
- void StopTrackingHeapObjects();
- /**
- * Starts gathering a sampling heap profile. A sampling heap profile is
- * similar to tcmalloc's heap profiler and Go's mprof. It samples object
- * allocations and builds an online 'sampling' heap profile. At any point in
- * time, this profile is expected to be a representative sample of objects
- * currently live in the system. Each sampled allocation includes the stack
- * trace at the time of allocation, which makes this really useful for memory
- * leak detection.
- *
- * This mechanism is intended to be cheap enough that it can be used in
- * production with minimal performance overhead.
- *
- * Allocations are sampled using a randomized Poisson process. On average, one
- * allocation will be sampled every |sample_interval| bytes allocated. The
- * |stack_depth| parameter controls the maximum number of stack frames to be
- * captured on each allocation.
- *
- * NOTE: This is a proof-of-concept at this point. Right now we only sample
- * newspace allocations. Support for paged space allocation (e.g. pre-tenured
- * objects, large objects, code objects, etc.) and native allocations
- * doesn't exist yet, but is anticipated in the future.
- *
- * Objects allocated before the sampling is started will not be included in
- * the profile.
- *
- * Returns false if a sampling heap profiler is already running.
- */
- bool StartSamplingHeapProfiler(uint64_t sample_interval = 512 * 1024,
- int stack_depth = 16,
- SamplingFlags flags = kSamplingNoFlags);
- /**
- * Stops the sampling heap profile and discards the current profile.
- */
- void StopSamplingHeapProfiler();
- /**
- * Returns the sampled profile of allocations allocated (and still live) since
- * StartSamplingHeapProfiler was called. The ownership of the pointer is
- * transferred to the caller. Returns nullptr if sampling heap profiler is not
- * active.
- */
- AllocationProfile* GetAllocationProfile();
- /**
- * Deletes all snapshots taken. All previously returned pointers to
- * snapshots and their contents become invalid after this call.
- */
- void DeleteAllHeapSnapshots();
- void AddBuildEmbedderGraphCallback(BuildEmbedderGraphCallback callback,
- void* data);
- void RemoveBuildEmbedderGraphCallback(BuildEmbedderGraphCallback callback,
- void* data);
- void SetGetDetachednessCallback(GetDetachednessCallback callback, void* data);
- /**
- * 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;
- private:
- HeapProfiler();
- ~HeapProfiler();
- HeapProfiler(const HeapProfiler&);
- HeapProfiler& operator=(const HeapProfiler&);
- };
- /**
- * 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.
- };
- #define CODE_EVENTS_LIST(V) \
- V(Builtin) \
- V(Callback) \
- V(Eval) \
- V(Function) \
- V(InterpretedFunction) \
- V(Handler) \
- V(BytecodeHandler) \
- V(LazyCompile) \
- V(RegExp) \
- V(Script) \
- V(Stub) \
- V(Relocation)
- /**
- * Note that this enum may be extended in the future. Please include a default
- * case if this enum is used in a switch statement.
- */
- enum CodeEventType {
- kUnknownType = 0
- #define V(Name) , k##Name##Type
- CODE_EVENTS_LIST(V)
- #undef V
- };
- /**
- * Representation of a code creation event
- */
- class V8_EXPORT CodeEvent {
- public:
- uintptr_t GetCodeStartAddress();
- size_t GetCodeSize();
- Local<String> GetFunctionName();
- Local<String> GetScriptName();
- int GetScriptLine();
- int GetScriptColumn();
- /**
- * NOTE (mmarchini): We can't allocate objects in the heap when we collect
- * existing code, and both the code type and the comment are not stored in the
- * heap, so we return those as const char*.
- */
- CodeEventType GetCodeType();
- const char* GetComment();
- static const char* GetCodeEventTypeName(CodeEventType code_event_type);
- uintptr_t GetPreviousCodeStartAddress();
- };
- /**
- * Interface to listen to code creation and code relocation events.
- */
- class V8_EXPORT CodeEventHandler {
- public:
- /**
- * Creates a new listener for the |isolate|. The isolate must be initialized.
- * The listener object must be disposed after use by calling |Dispose| method.
- * Multiple listeners can be created for the same isolate.
- */
- explicit CodeEventHandler(Isolate* isolate);
- virtual ~CodeEventHandler();
- /**
- * Handle is called every time a code object is created or moved. Information
- * about each code event will be available through the `code_event`
- * parameter.
- *
- * When the CodeEventType is kRelocationType, the code for this CodeEvent has
- * moved from `GetPreviousCodeStartAddress()` to `GetCodeStartAddress()`.
- */
- virtual void Handle(CodeEvent* code_event) = 0;
- /**
- * Call `Enable()` to starts listening to code creation and code relocation
- * events. These events will be handled by `Handle()`.
- */
- void Enable();
- /**
- * Call `Disable()` to stop listening to code creation and code relocation
- * events.
- */
- void Disable();
- private:
- CodeEventHandler();
- CodeEventHandler(const CodeEventHandler&);
- CodeEventHandler& operator=(const CodeEventHandler&);
- void* internal_listener_;
- };
- } // namespace v8
- #endif // V8_V8_PROFILER_H_
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