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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
#ifndef DMD_h___
#define DMD_h___
#include <stdarg.h>
#include <string.h>
#include <utility>
#include "mozilla/DebugOnly.h"
#include "mozilla/Types.h"
#include "mozilla/UniquePtr.h"
#include "replace_malloc_bridge.h"
namespace mozilla {
class JSONWriteFunc;
namespace dmd {
struct Sizes {
size_t mStackTracesUsed;
size_t mStackTracesUnused;
size_t mStackTraceTable;
size_t mLiveBlockTable;
size_t mDeadBlockTable;
Sizes() { Clear(); }
void Clear() { memset(this, 0, sizeof(Sizes)); }
};
// See further below for a description of each method. The DMDFuncs class
// should contain a virtual method for each of them (except IsRunning,
// which can be inferred from the DMDFuncs singleton existing).
struct DMDFuncs {
virtual void Report(const void*);
virtual void ReportOnAlloc(const void*);
virtual void ClearReports();
virtual void Analyze(UniquePtr<JSONWriteFunc>);
virtual void SizeOf(Sizes*);
virtual void StatusMsg(const char*, va_list) MOZ_FORMAT_PRINTF(2, 0);
virtual void ResetEverything(const char*);
#ifndef REPLACE_MALLOC_IMPL
// We deliberately don't use ReplaceMalloc::GetDMDFuncs here, because if we
// did, the following would happen.
// - The code footprint of each call to Get() larger as GetDMDFuncs ends
// up inlined.
// - When no replace-malloc library is loaded, the number of instructions
// executed is equivalent, but don't necessarily fit in the same cache
// line.
// - When a non-DMD replace-malloc library is loaded, the overhead is
// higher because there is first a check for the replace malloc bridge
// and then for the DMDFuncs singleton.
// Initializing the DMDFuncs singleton on the first access makes the
// overhead even worse. Either Get() is inlined and massive, or it isn't
// and a simple value check becomes a function call.
static DMDFuncs* Get() { return sSingleton.Get(); }
private:
// Wrapper class keeping a pointer to the DMD functions. It is statically
// initialized because it needs to be set early enough.
// Debug builds also check that it's never accessed before the static
// initialization actually occured, which could be the case if some other
// static initializer ended up calling into DMD.
class Singleton {
public:
Singleton()
: mValue(ReplaceMalloc::GetDMDFuncs())
# ifdef DEBUG
,
mInitialized(true)
# endif
{
}
DMDFuncs* Get() {
MOZ_ASSERT(mInitialized);
return mValue;
}
private:
DMDFuncs* mValue;
# ifdef DEBUG
bool mInitialized;
# endif
};
// This singleton pointer must be defined on the program side. In Gecko,
// this is done in xpcom/base/nsMemoryInfoDumper.cpp.
static /* DMDFuncs:: */ Singleton sSingleton;
#endif
};
#ifndef REPLACE_MALLOC_IMPL
// Mark a heap block as reported by a memory reporter.
inline void Report(const void* aPtr) {
DMDFuncs* funcs = DMDFuncs::Get();
if (funcs) {
funcs->Report(aPtr);
}
}
// Mark a heap block as reported immediately on allocation.
inline void ReportOnAlloc(const void* aPtr) {
DMDFuncs* funcs = DMDFuncs::Get();
if (funcs) {
funcs->ReportOnAlloc(aPtr);
}
}
// Clears existing reportedness data from any prior runs of the memory
// reporters. The following sequence should be used.
// - ClearReports()
// - run the memory reporters
// - Analyze()
// This sequence avoids spurious twice-reported warnings.
inline void ClearReports() {
DMDFuncs* funcs = DMDFuncs::Get();
if (funcs) {
funcs->ClearReports();
}
}
// Determines which heap blocks have been reported, and dumps JSON output
// (via |aWriter|) describing the heap.
//
// The following sample output contains comments that explain the format and
// design choices. The output files can be quite large, so a number of
// decisions were made to minimize size, such as using short property names and
// omitting properties whenever possible.
//
// {
// // The version number of the format, which will be incremented each time
// // backwards-incompatible changes are made. A mandatory integer.
// //
// // Version history:
// "version": 5,
//
// // Information about how DMD was invoked. A mandatory object.
// "invocation": {
// // The contents of the $DMD environment variable. A string, or |null| if
// // $DMD is undefined.
// "dmdEnvVar": "--mode=dark-matter",
//
// // The profiling mode. A mandatory string taking one of the following
// // values: "live", "dark-matter", "cumulative", "scan".
// "mode": "dark-matter",
// },
//
// // Details of all analyzed heap blocks. A mandatory array.
// "blockList": [
// // An example of a heap block.
// {
// // Requested size, in bytes. This is a mandatory integer.
// "req": 3584,
//
// // Requested slop size, in bytes. This is mandatory if it is non-zero,
// // but omitted otherwise.
// "slop": 512,
//
// // The stack trace at which the block was allocated. An optional
// // string that indexes into the "traceTable" object. If omitted, no
// // allocation stack trace was recorded for the block.
// "alloc": "A",
//
// // One or more stack traces at which this heap block was reported by a
// // memory reporter. An optional array that will only be present in
// // "dark-matter" mode. The elements are strings that index into
// // the "traceTable" object.
// "reps": ["B"]
//
// // The number of heap blocks with exactly the above properties. This
// // is mandatory if it is greater than one, but omitted otherwise.
// // (Blocks with identical properties don't have to be aggregated via
// // this property, but it can greatly reduce output file size.)
// "num": 5,
//
// // The address of the block. This is mandatory in "scan" mode, but
// // omitted otherwise.
// "addr": "4e4e4e4e",
//
// // The contents of the block, read one word at a time. This is
// // mandatory in "scan" mode for blocks at least one word long, but
// // omitted otherwise.
// "contents": ["0", "6", "7f7f7f7f", "0"]
// }
// ],
//
// // The stack traces referenced by elements of the "blockList" array. This
// // could be an array, but making it an object makes it easier to see
// // which stacks correspond to which references in the "blockList" array.
// "traceTable": {
// // Each property corresponds to a stack trace mentioned in the "blocks"
// // object. Each element is an index into the "frameTable" object.
// "A": ["D", "E"],
// "B": ["F", "G"]
// },
//
// // The stack frames referenced by the "traceTable" object. The
// // descriptions can be quite long, so they are stored separately from the
// // "traceTable" object so that each one only has to be written once.
// // This could also be an array, but again, making it an object makes it
// // easier to see which frames correspond to which references in the
// // "traceTable" object.
// "frameTable": {
// // Each property key is a frame key mentioned in the "traceTable" object.
// // Each property value is a string containing a frame description. Each
// // frame description must be in a format recognized by `fix_stacks.py`,
// // which requires a frame number at the start. Because each stack frame
// // description in this table can be shared between multiple stack
// // traces, we use a dummy value of #00. The proper frame number can be
// // reconstructed later by scripts that output stack traces in a
// // conventional non-shared format.
// "D": "#00: foo (Foo.cpp:123)",
// "E": "#00: bar (Bar.cpp:234)",
// "F": "#00: baz (Baz.cpp:345)",
// "G": "#00: quux (Quux.cpp:456)"
// }
// }
//
// Implementation note: normally, this function wouldn't be templated, but in
// that case, the function is compiled, which makes the destructor for the
// UniquePtr fire up, and that needs JSONWriteFunc to be fully defined. That,
// in turn, requires to include JSONWriter.h, which includes
// double-conversion.h, which ends up breaking various things built with
// -Werror for various reasons.
//
template <typename JSONWriteFunc>
inline void Analyze(UniquePtr<JSONWriteFunc> aWriteFunc) {
DMDFuncs* funcs = DMDFuncs::Get();
if (funcs) {
funcs->Analyze(std::move(aWriteFunc));
}
}
// Gets the size of various data structures. Used to implement a memory
// reporter for DMD.
inline void SizeOf(Sizes* aSizes) {
DMDFuncs* funcs = DMDFuncs::Get();
if (funcs) {
funcs->SizeOf(aSizes);
}
}
// Prints a status message prefixed with "DMD[<pid>]". Use sparingly.
MOZ_FORMAT_PRINTF(1, 2)
inline void StatusMsg(const char* aFmt, ...) {
DMDFuncs* funcs = DMDFuncs::Get();
if (funcs) {
va_list ap;
va_start(ap, aFmt);
funcs->StatusMsg(aFmt, ap);
va_end(ap);
}
}
// Indicates whether or not DMD is running.
inline bool IsRunning() { return !!DMDFuncs::Get(); }
// Resets all DMD options and then sets new ones according to those specified
// in |aOptions|. Also clears all recorded data about allocations. Only used
// for testing purposes.
inline void ResetEverything(const char* aOptions) {
DMDFuncs* funcs = DMDFuncs::Get();
if (funcs) {
funcs->ResetEverything(aOptions);
}
}
#endif
} // namespace dmd
} // namespace mozilla
#endif /* DMD_h___ */