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// Copyright (c) 2005, 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
//
// Routine that uses sbrk/mmap to allocate memory from the system.
// Useful for implementing malloc.
#ifndef TCMALLOC_SYSTEM_ALLOC_H_
#define TCMALLOC_SYSTEM_ALLOC_H_
#include <config.h>
#include "internal_logging.h"
// REQUIRES: "alignment" is a power of two or "0" to indicate default alignment
//
// Allocate and return "N" bytes of zeroed memory.
//
// If actual_bytes is NULL then the returned memory is exactly the
// requested size. If actual bytes is non-NULL then the allocator
// may optionally return more bytes than asked for (i.e. return an
// entire "huge" page if a huge page allocator is in use).
//
// The returned pointer is a multiple of "alignment" if non-zero.
//
// Returns NULL when out of memory.
extern void* TCMalloc_SystemAlloc(size_t bytes, size_t *actual_bytes,
size_t alignment = 0);
// This call is a hint to the operating system that the pages
// contained in the specified range of memory will not be used for a
// while, and can be released for use by other processes or the OS.
// Pages which are released in this way may be destroyed (zeroed) by
// the OS. The benefit of this function is that it frees memory for
// use by the system, the cost is that the pages are faulted back into
// the address space next time they are touched, which can impact
// performance. (Only pages fully covered by the memory region will
// be released, partial pages will not.)
extern void TCMalloc_SystemRelease(void* start, size_t length);
// Interface to a pluggable system allocator.
class SysAllocator {
public:
SysAllocator()
: usable_(true),
failed_(false) {
};
virtual ~SysAllocator() {};
virtual void* Alloc(size_t size, size_t *actual_size, size_t alignment) = 0;
// Populate the map with whatever properties the specified allocator finds
// useful for debugging (such as number of bytes allocated and whether the
// allocator has failed). The callee is responsible for any necessary
// locking (and avoiding deadlock).
virtual void DumpStats(TCMalloc_Printer* printer) = 0;
// So the allocator can be turned off at compile time
bool usable_;
// Did this allocator fail? If so, we don't need to retry more than twice.
bool failed_;
};
// Register a new system allocator. The priority determines the order in
// which the allocators will be invoked. Allocators with numerically lower
// priority are tried first. To keep things simple, the priority of various
// allocators is known at compile time.
//
// Valid range of priorities: [0, kMaxDynamicAllocators)
//
// Please note that we can't use complex data structures and cause
// recursive calls to malloc within this function. So all data structures
// are statically allocated.
//
// Returns true on success. Does nothing on failure.
extern PERFTOOLS_DLL_DECL bool RegisterSystemAllocator(SysAllocator *allocator,
int priority);
// Number of SysAllocators known to call RegisterSystemAllocator
static const int kMaxDynamicAllocators = 2;
// Retrieve the current state of various system allocators.
extern PERFTOOLS_DLL_DECL void DumpSystemAllocatorStats(TCMalloc_Printer* printer);
#endif /* TCMALLOC_SYSTEM_ALLOC_H_ */
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