v8/include/v8-profiler.h
loislo@chromium.org f6b7ec4da0 HeapProfiler: very slow ~4min "take snapshot time" for 80MB gmail heap.
The reason of that is a number of cons strings in the app.
The app constructs a json string and as a result v8 heap has
a very long chain of cons strings.

Profiler counts all these strings as plain String objects and
assign the content of the strings as node names.

It required O(n^2) time and O(n^2) memory.

Solution: I introduced two new types, kConsString and kSliced string.
They do not use the content of the string for names. So the problem disappeared.

The heap profiler usability problem will be solved on Blink side.

BUG=285770
R=yangguo@chromium.org

Review URL: https://codereview.chromium.org/23460027

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@16611 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
2013-09-10 11:12:35 +00:00

575 lines
18 KiB
C++

// 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
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// 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"
/**
* 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 bailout reason for the function
* if the optimization was disabled for it.
*/
const char* GetBailoutReason() const;
/** DEPRECATED. Please use GetHitCount instead.
* Returns the count of samples where function was currently executing.
*/
V8_DEPRECATED(double GetSelfSamplesCount() 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;
};
/**
* 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);
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_