// 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 <vector>
#include "v8.h" // NOLINT(build/include)
/**
* Profiler support for the V8 JavaScript engine.
*/
namespace v8 {
class HeapGraphNode;
struct HeapStatsUpdate;
typedef uint32_t SnapshotObjectId;
struct CpuProfileDeoptFrame {
int script_id;
size_t position;
};
} // 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;
};
/** Returns function name (empty string for anonymous functions.) */
Local<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. */
Local<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 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 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;
/** 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 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();
};
/**
* 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);
/**
* 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 StartProfiling(Local<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.
*/
CpuProfile* StopProfiling(Local<String> title);
/**
* Force collection of a sample. Must be called on the VM thread.
* Recording the forced sample does not contribute to the aggregated
* profile statistics.
*/
void CollectSample();
/**
* Tells the profiler whether the embedder is idle.
*/
void SetIdle(bool is_idle);
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, 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.
kSymbol = 12, // A Symbol (ES6).
kSimdValue = 13 // A SIMD value stored in the heap (Proposed ES7).
};
/** 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 { // NOLINT
public:
enum WriteResult {
kContinue = 0,
kAbort = 1
};
virtual ~OutputStream() {}
/** 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 { // NOLINT
public:
enum ControlOption {
kContinue = 0,
kAbort = 1
};
virtual ~ActivityControl() {}
/**
* Notify about current progress. The activity can be stopped by
* returning kAbort as the callback result.
*/
virtual ControlOption ReportProgressValue(int done, int 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;
/**
* 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;
};
/**
* 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 ~AllocationProfile() {}
static const int kNoLineNumberInfo = Message::kNoLineNumberInfo;
static const int kNoColumnNumberInfo = Message::kNoColumnInfo;
};
/**
* 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 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,
Local<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(Local<Value> 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() {}
};
/**
* Takes a heap snapshot and returns it.
*/
const HeapSnapshot* TakeHeapSnapshot(
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.
*
* |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 = NULL);
/**
* 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
* transfered 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();
/** 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);
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, it 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_