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+// -*- Mode: C++; c-basic-offset: 2; indent-tabs-mode: nil -*-
+// 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 <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 PERFTOOLS_DLL_DECL 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.central_cache_free_bytes"
+  //      Number of free bytes in the central cache that have been
+  //      assigned to size classes. 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.transfer_cache_free_bytes"
+  //      Number of free bytes that are waiting to be transfered between
+  //      the central cache and a thread cache. 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.thread_cache_free_bytes"
+  //      Number of free bytes in thread caches. 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_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);
+
+  // 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_