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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=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
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
// Internal Base Profiler utilities.
#ifndef BaseProfilerDetail_h
#define BaseProfilerDetail_h
#include "mozilla/Atomics.h"
#include "mozilla/Maybe.h"
#include "mozilla/PlatformMutex.h"
#ifndef MOZ_GECKO_PROFILER
# error Do not #include this header when MOZ_GECKO_PROFILER is not #defined.
#endif
namespace mozilla {
namespace baseprofiler {
// Implemented in platform.cpp
MFBT_API int profiler_current_thread_id();
namespace detail {
// Thin shell around mozglue PlatformMutex, for Base Profiler internal use.
class BaseProfilerMutex : private ::mozilla::detail::MutexImpl {
public:
BaseProfilerMutex() : ::mozilla::detail::MutexImpl() {}
explicit BaseProfilerMutex(const char* aName)
: ::mozilla::detail::MutexImpl(), mName(aName) {}
BaseProfilerMutex(const BaseProfilerMutex&) = delete;
BaseProfilerMutex& operator=(const BaseProfilerMutex&) = delete;
BaseProfilerMutex(BaseProfilerMutex&&) = delete;
BaseProfilerMutex& operator=(BaseProfilerMutex&&) = delete;
#ifdef DEBUG
~BaseProfilerMutex() { MOZ_ASSERT(mOwningThreadId == 0); }
#endif // DEBUG
[[nodiscard]] bool IsLockedOnCurrentThread() const {
return mOwningThreadId == baseprofiler::profiler_current_thread_id();
}
void AssertCurrentThreadOwns() const {
MOZ_ASSERT(IsLockedOnCurrentThread());
}
void Lock() {
const int tid = baseprofiler::profiler_current_thread_id();
MOZ_ASSERT(tid != 0);
MOZ_ASSERT(!IsLockedOnCurrentThread(), "Recursive locking");
::mozilla::detail::MutexImpl::lock();
MOZ_ASSERT(mOwningThreadId == 0, "Not unlocked properly");
mOwningThreadId = tid;
}
[[nodiscard]] bool TryLock() {
const int tid = baseprofiler::profiler_current_thread_id();
MOZ_ASSERT(tid != 0);
MOZ_ASSERT(!IsLockedOnCurrentThread(), "Recursive locking");
if (!::mozilla::detail::MutexImpl::tryLock()) {
// Failed to lock, nothing more to do.
return false;
}
MOZ_ASSERT(mOwningThreadId == 0, "Not unlocked properly");
mOwningThreadId = tid;
return true;
}
void Unlock() {
MOZ_ASSERT(IsLockedOnCurrentThread(), "Unlocking when not locked here");
// We're still holding the mutex here, so it's safe to just reset
// `mOwningThreadId`.
mOwningThreadId = 0;
::mozilla::detail::MutexImpl::unlock();
}
const char* GetName() const { return mName; }
private:
// Thread currently owning the lock, or 0.
// Atomic because it may be read at any time independent of the mutex.
// Relaxed because threads only need to know if they own it already, so:
// - If it's their id, only *they* wrote that value with a locked mutex.
// - If it's different from their thread id it doesn't matter what other
// number it is (0 or another id) and that it can change again at any time.
Atomic<int, MemoryOrdering::Relaxed> mOwningThreadId{0};
const char* mName = nullptr;
};
// RAII class to lock a mutex.
class MOZ_RAII BaseProfilerAutoLock {
public:
explicit BaseProfilerAutoLock(BaseProfilerMutex& aMutex) : mMutex(aMutex) {
mMutex.Lock();
}
BaseProfilerAutoLock(const BaseProfilerAutoLock&) = delete;
BaseProfilerAutoLock& operator=(const BaseProfilerAutoLock&) = delete;
BaseProfilerAutoLock(BaseProfilerAutoLock&&) = delete;
BaseProfilerAutoLock& operator=(BaseProfilerAutoLock&&) = delete;
~BaseProfilerAutoLock() { mMutex.Unlock(); }
private:
BaseProfilerMutex& mMutex;
};
// Thin shell around mozglue PlatformMutex, for Base Profiler internal use.
// Actual mutex may be disabled at construction time.
class BaseProfilerMaybeMutex : private ::mozilla::detail::MutexImpl {
public:
explicit BaseProfilerMaybeMutex(bool aActivate) {
if (aActivate) {
mMaybeMutex.emplace();
}
}
BaseProfilerMaybeMutex(const BaseProfilerMaybeMutex&) = delete;
BaseProfilerMaybeMutex& operator=(const BaseProfilerMaybeMutex&) = delete;
BaseProfilerMaybeMutex(BaseProfilerMaybeMutex&&) = delete;
BaseProfilerMaybeMutex& operator=(BaseProfilerMaybeMutex&&) = delete;
~BaseProfilerMaybeMutex() = default;
bool IsActivated() const { return mMaybeMutex.isSome(); }
[[nodiscard]] bool IsActivatedAndLockedOnCurrentThread() const {
if (!IsActivated()) {
// Not activated, so we can never be locked.
return false;
}
return mMaybeMutex->IsLockedOnCurrentThread();
}
void AssertCurrentThreadOwns() const {
#ifdef DEBUG
if (IsActivated()) {
mMaybeMutex->AssertCurrentThreadOwns();
}
#endif // DEBUG
}
void Lock() {
if (IsActivated()) {
mMaybeMutex->Lock();
}
}
void Unlock() {
if (IsActivated()) {
mMaybeMutex->Unlock();
}
}
private:
Maybe<BaseProfilerMutex> mMaybeMutex;
};
// RAII class to lock a mutex.
class MOZ_RAII BaseProfilerMaybeAutoLock {
public:
explicit BaseProfilerMaybeAutoLock(BaseProfilerMaybeMutex& aMaybeMutex)
: mMaybeMutex(aMaybeMutex) {
mMaybeMutex.Lock();
}
BaseProfilerMaybeAutoLock(const BaseProfilerMaybeAutoLock&) = delete;
BaseProfilerMaybeAutoLock& operator=(const BaseProfilerMaybeAutoLock&) =
delete;
BaseProfilerMaybeAutoLock(BaseProfilerMaybeAutoLock&&) = delete;
BaseProfilerMaybeAutoLock& operator=(BaseProfilerMaybeAutoLock&&) = delete;
~BaseProfilerMaybeAutoLock() { mMaybeMutex.Unlock(); }
private:
BaseProfilerMaybeMutex& mMaybeMutex;
};
} // namespace detail
} // namespace baseprofiler
} // namespace mozilla
#endif // BaseProfilerDetail_h
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