// Copyright (c) 2012, Google Inc.
// 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.
// ---
// Author: Sanjay Ghemawat <opensource@google.com>
//
// Extra extensions exported by some malloc implementations. These
// extensions are accessed through a virtual base class so an
// application can link against a malloc that does not implement these
// extensions, and it will get default versions that do nothing.
//
// NOTE FOR C USERS: If you wish to use this functionality from within
// a C program, see malloc_extension_c.h.
#ifndef BASE_MALLOC_EXTENSION_H_
#define BASE_MALLOC_EXTENSION_H_
#include <stddef.h>
// I can't #include config.h in this public API file, but I should
// really use configure (and make malloc_extension.h a .in file) to
// figure out if the system has stdint.h or not. But I'm lazy, so
// for now I'm assuming it's a problem only with MSVC.
#ifndef _MSC_VER
#include <stdint.h>
#endif
#include <string>
#include <vector>
// Annoying stuff for windows -- makes sure clients can import these functions
#ifndef PERFTOOLS_DLL_DECL
# ifdef _WIN32
# define PERFTOOLS_DLL_DECL __declspec(dllimport)
# else
# define PERFTOOLS_DLL_DECL
# endif
#endif
static const int kMallocHistogramSize = 64;
// One day, we could support other types of writers (perhaps for C?)
typedef std::string MallocExtensionWriter;
namespace base {
struct MallocRange;
}
// Interface to a pluggable system allocator.
class SysAllocator {
public:
SysAllocator() {
}
virtual ~SysAllocator();
// Allocates "size"-byte of memory from system aligned with "alignment".
// Returns NULL if failed. Otherwise, the returned pointer p up to and
// including (p + actual_size -1) have been allocated.
virtual void* Alloc(size_t size, size_t *actual_size, size_t alignment) = 0;
};
// The default implementations of the following routines do nothing.
// All implementations should be thread-safe; the current one
// (TCMallocImplementation) is.
class PERFTOOLS_DLL_DECL MallocExtension {
public:
virtual ~MallocExtension();
// Call this very early in the program execution -- say, in a global
// constructor -- to set up parameters and state needed by all
// instrumented malloc implemenatations. One example: this routine
// sets environemnt variables to tell STL to use libc's malloc()
// instead of doing its own memory management. This is safe to call
// multiple times, as long as each time is before threads start up.
static void Initialize();
// See "verify_memory.h" to see what these routines do
virtual bool VerifyAllMemory();
virtual bool VerifyNewMemory(const void* p);
virtual bool VerifyArrayNewMemory(const void* p);
virtual bool VerifyMallocMemory(const void* p);
virtual bool MallocMemoryStats(int* blocks, size_t* total,
int histogram[kMallocHistogramSize]);
// Get a human readable description of the current state of the malloc
// data structures. The state is stored as a null-terminated string
// in a prefix of "buffer[0,buffer_length-1]".
// REQUIRES: buffer_length > 0.
virtual void GetStats(char* buffer, int buffer_length);
// Outputs to "writer" a sample of live objects and the stack traces
// that allocated these objects. The format of the returned output
// is equivalent to the output of the heap profiler and can
// therefore be passed to "pprof". This function is equivalent to
// ReadStackTraces. The main difference is that this function returns
// serialized data appropriately formatted for use by the pprof tool.
// NOTE: by default, tcmalloc does not do any heap sampling, and this
// function will always return an empty sample. To get useful
// data from GetHeapSample, you must also set the environment
// variable TCMALLOC_SAMPLE_PARAMETER to a value such as 524288.
virtual void GetHeapSample(MallocExtensionWriter* writer);
// Outputs to "writer" the stack traces that caused growth in the
// address space size. The format of the returned output is
// equivalent to the output of the heap profiler and can therefore
// be passed to "pprof". This function is equivalent to
// ReadHeapGrowthStackTraces. The main difference is that this function
// returns serialized data appropriately formatted for use by the
// pprof tool. (This does not depend on, or require,
// TCMALLOC_SAMPLE_PARAMETER.)
virtual void GetHeapGrowthStacks(MallocExtensionWriter* writer);
// Invokes func(arg, range) for every controlled memory
// range. *range is filled in with information about the range.
//
// This is a best-effort interface useful only for performance
// analysis. The implementation may not call func at all.
typedef void (RangeFunction)(void*, const base::MallocRange*);
virtual void Ranges(void* arg, RangeFunction func);
// -------------------------------------------------------------------
// Control operations for getting and setting malloc implementation
// specific parameters. Some currently useful properties:
//
// generic
// -------
// "generic.current_allocated_bytes"
// Number of bytes currently allocated by application
// This property is not writable.
//
// "generic.heap_size"
// Number of bytes in the heap ==
// current_allocated_bytes +
// fragmentation +
// freed memory regions
// This property is not writable.
//
// tcmalloc
// --------
// "tcmalloc.max_total_thread_cache_bytes"
// Upper limit on total number of bytes stored across all
// per-thread caches. Default: 16MB.
//
// "tcmalloc.current_total_thread_cache_bytes"
// Number of bytes used across all thread caches.
// This property is not writable.
//
// "tcmalloc.pageheap_free_bytes"
// Number of bytes in free, mapped pages in page heap. These
// bytes can be used to fulfill allocation requests. They
// always count towards virtual memory usage, and unless the
// underlying memory is swapped out by the OS, they also count
// towards physical memory usage. This property is not writable.
//
// "tcmalloc.pageheap_unmapped_bytes"
// Number of bytes in free, unmapped pages in page heap.
// These are bytes that have been released back to the OS,
// possibly by one of the MallocExtension "Release" calls.
// They can be used to fulfill allocation requests, but
// typically incur a page fault. They always count towards
// virtual memory usage, and depending on the OS, typically
// do not count towards physical memory usage. This property
// is not writable.
// -------------------------------------------------------------------
// Get the named "property"'s value. Returns true if the property
// is known. Returns false if the property is not a valid property
// name for the current malloc implementation.
// REQUIRES: property != NULL; value != NULL
virtual bool GetNumericProperty(const char* property, size_t* value);
// Set the named "property"'s value. Returns true if the property
// is known and writable. Returns false if the property is not a
// valid property name for the current malloc implementation, or
// is not writable.
// REQUIRES: property != NULL
virtual bool SetNumericProperty(const char* property, size_t value);
// Mark the current thread as "idle". This routine may optionally
// be called by threads as a hint to the malloc implementation that
// any thread-specific resources should be released. Note: this may
// be an expensive routine, so it should not be called too often.
//
// Also, if the code that calls this routine will go to sleep for
// a while, it should take care to not allocate anything between
// the call to this routine and the beginning of the sleep.
//
// Most malloc implementations ignore this routine.
virtual void MarkThreadIdle();
// Mark the current thread as "busy". This routine should be
// called after MarkThreadIdle() if the thread will now do more
// work. If this method is not called, performance may suffer.
//
// Most malloc implementations ignore this routine.
virtual void MarkThreadBusy();
// Gets the system allocator used by the malloc extension instance. Returns
// NULL for malloc implementations that do not support pluggable system
// allocators.
virtual SysAllocator* GetSystemAllocator();
// Sets the system allocator to the specified.
//
// Users could register their own system allocators for malloc implementation
// that supports pluggable system allocators, such as TCMalloc, by doing:
// alloc = new MyOwnSysAllocator();
// MallocExtension::instance()->SetSystemAllocator(alloc);
// It's up to users whether to fall back (recommended) to the default
// system allocator (use GetSystemAllocator() above) or not. The caller is
// responsible to any necessary locking.
// See tcmalloc/system-alloc.h for the interface and
// tcmalloc/memfs_malloc.cc for the examples.
//
// It's a no-op for malloc implementations that do not support pluggable
// system allocators.
virtual void SetSystemAllocator(SysAllocator *a);
// Try to release num_bytes of free memory back to the operating
// system for reuse. Use this extension with caution -- to get this
// memory back may require faulting pages back in by the OS, and
// that may be slow. (Currently only implemented in tcmalloc.)
virtual void ReleaseToSystem(size_t num_bytes);
// Same as ReleaseToSystem() but release as much memory as possible.
virtual void ReleaseFreeMemory();
// Sets the rate at which we release unused memory to the system.
// Zero means we never release memory back to the system. Increase
// this flag to return memory faster; decrease it to return memory
// slower. Reasonable rates are in the range [0,10]. (Currently
// only implemented in tcmalloc).
virtual void SetMemoryReleaseRate(double rate);
// Gets the release rate. Returns a value < 0 if unknown.
virtual double GetMemoryReleaseRate();
// Returns the estimated number of bytes that will be allocated for
// a request of "size" bytes. This is an estimate: an allocation of
// SIZE bytes may reserve more bytes, but will never reserve less.
// (Currently only implemented in tcmalloc, other implementations
// always return SIZE.)
// This is equivalent to malloc_good_size() in OS X.
virtual size_t GetEstimatedAllocatedSize(size_t size);
// Returns the actual number N of bytes reserved by tcmalloc for the
// pointer p. The client is allowed to use the range of bytes
// [p, p+N) in any way it wishes (i.e. N is the "usable size" of this
// allocation). This number may be equal to or greater than the number
// of bytes requested when p was allocated.
// p must have been allocated by this malloc implementation,
// must not be an interior pointer -- that is, must be exactly
// the pointer returned to by malloc() et al., not some offset
// from that -- and should not have been freed yet. p may be NULL.
// (Currently only implemented in tcmalloc; other implementations
// will return 0.)
// This is equivalent to malloc_size() in OS X, malloc_usable_size()
// in glibc, and _msize() for windows.
virtual size_t GetAllocatedSize(const void* p);
// Returns kOwned if this malloc implementation allocated the memory
// pointed to by p, or kNotOwned if some other malloc implementation
// allocated it or p is NULL. May also return kUnknownOwnership if
// the malloc implementation does not keep track of ownership.
// REQUIRES: p must be a value returned from a previous call to
// malloc(), calloc(), realloc(), memalign(), posix_memalign(),
// valloc(), pvalloc(), new, or new[], and must refer to memory that
// is currently allocated (so, for instance, you should not pass in
// a pointer after having called free() on it).
enum Ownership {
// NOTE: Enum values MUST be kept in sync with the version in
// malloc_extension_c.h
kUnknownOwnership = 0,
kOwned,
kNotOwned
};
virtual Ownership GetOwnership(const void* p);
// The current malloc implementation. Always non-NULL.
static MallocExtension* instance();
// Change the malloc implementation. Typically called by the
// malloc implementation during initialization.
static void Register(MallocExtension* implementation);
// On the current thread, return the total number of bytes allocated.
// This function is added in Chromium for profiling.
// Currently only implemented in tcmalloc. Returns 0 if tcmalloc is not used.
// Note that malloc_extension can be used without tcmalloc if gperftools'
// heap-profiler is enabled without the tcmalloc memory allocator.
static unsigned int GetBytesAllocatedOnCurrentThread();
// Returns detailed information about malloc's freelists. For each list,
// return a FreeListInfo:
struct FreeListInfo {
size_t min_object_size;
size_t max_object_size;
size_t total_bytes_free;
const char* type;
};
// Each item in the vector refers to a different freelist. The lists
// are identified by the range of allocations that objects in the
// list can satisfy ([min_object_size, max_object_size]) and the
// type of freelist (see below). The current size of the list is
// returned in total_bytes_free (which count against a processes
// resident and virtual size).
//
// Currently supported types are:
//
// "tcmalloc.page{_unmapped}" - tcmalloc's page heap. An entry for each size
// class in the page heap is returned. Bytes in "page_unmapped"
// are no longer backed by physical memory and do not count against
// the resident size of a process.
//
// "tcmalloc.large{_unmapped}" - tcmalloc's list of objects larger
// than the largest page heap size class. Only one "large"
// entry is returned. There is no upper-bound on the size
// of objects in the large free list; this call returns
// kint64max for max_object_size. Bytes in
// "large_unmapped" are no longer backed by physical memory
// and do not count against the resident size of a process.
//
// "tcmalloc.central" - tcmalloc's central free-list. One entry per
// size-class is returned. Never unmapped.
//
// "debug.free_queue" - free objects queued by the debug allocator
// and not returned to tcmalloc.
//
// "tcmalloc.thread" - tcmalloc's per-thread caches. Never unmapped.
virtual void GetFreeListSizes(std::vector<FreeListInfo>* v);
// Get a list of stack traces of sampled allocation points. Returns
// a pointer to a "new[]-ed" result array, and stores the sample
// period in "sample_period".
//
// The state is stored as a sequence of adjacent entries
// in the returned array. Each entry has the following form:
// uintptr_t count; // Number of objects with following trace
// uintptr_t size; // Total size of objects with following trace
// uintptr_t depth; // Number of PC values in stack trace
// void* stack[depth]; // PC values that form the stack trace
//
// The list of entries is terminated by a "count" of 0.
//
// It is the responsibility of the caller to "delete[]" the returned array.
//
// May return NULL to indicate no results.
//
// This is an internal extension. Callers should use the more
// convenient "GetHeapSample(string*)" method defined above.
virtual void** ReadStackTraces(int* sample_period);
// Like ReadStackTraces(), but returns stack traces that caused growth
// in the address space size.
virtual void** ReadHeapGrowthStackTraces();
};
namespace base {
// Information passed per range. More fields may be added later.
struct MallocRange {
enum Type {
INUSE, // Application is using this range
FREE, // Range is currently free
UNMAPPED, // Backing physical memory has been returned to the OS
UNKNOWN,
// More enum values may be added in the future
};
uintptr_t address; // Address of range
size_t length; // Byte length of range
Type type; // Type of this range
double fraction; // Fraction of range that is being used (0 if !INUSE)
// Perhaps add the following:
// - stack trace if this range was sampled
// - heap growth stack trace if applicable to this range
// - age when allocated (for inuse) or freed (if not in use)
};
} // namespace base
#endif // BASE_MALLOC_EXTENSION_H_