De-abseil, part 2: mutex, locks, (most) time
- util::Mutex is now a std::shared_timed_mutex, which is capable of
exclusive and shared locks.
- util::Lock is still present as a std::lock_guard<util::Mutex>.
- the locking annotations are preserved, but updated to the latest
supported by clang rather than using abseil's older/deprecated ones.
- ACQUIRE_LOCK macro is gone since we don't pass mutexes by pointer into
locks anymore (WTF abseil).
- ReleasableLock is gone. Instead there are now some llarp::util helper
methods to obtain unique and/or shared locks:
- `auto lock = util::unique_lock(mutex);` gets an RAII-but-also
unlockable object (std::unique_lock<T>, with T inferred from
`mutex`).
- `auto lock = util::shared_lock(mutex);` gets an RAII shared (i.e.
"reader") lock of the mutex.
- `auto lock = util::unique_locks(mutex1, mutex2, mutex3);` can be
used to atomically lock multiple mutexes at once (returning a
tuple of the locks).
This are templated on the mutex which makes them a bit more flexible
than using a concrete type: they can be used for any type of lockable
mutex, not only util::Mutex. (Some of the code here uses them for
getting locks around a std::mutex). Until C++17, using the RAII types
is painfully verbose:
```C++
// pre-C++17 - needing to figure out the mutex type here is annoying:
std::unique_lock<util::Mutex> lock(mutex);
// pre-C++17 and even more verbose (but at least the type isn't needed):
std::unique_lock<decltype(mutex)> lock(mutex);
// our compromise:
auto lock = util::unique_lock(mutex);
// C++17:
std::unique_lock lock(mutex);
```
All of these functions will also warn (under gcc or clang) if you
discard the return value. You can also do fancy things like
`auto l = util::unique_lock(mutex, std::adopt_lock)` (which lets a
lock take over an already-locked mutex).
- metrics code is gone, which also removes a big pile of code that was
only used by metrics:
- llarp::util::Scheduler
- llarp::thread::TimerQueue
- llarp::util::Stopwatch
5 years ago
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#pragma once
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#include <ciso646>
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De-abseil, part 2: mutex, locks, (most) time
- util::Mutex is now a std::shared_timed_mutex, which is capable of
exclusive and shared locks.
- util::Lock is still present as a std::lock_guard<util::Mutex>.
- the locking annotations are preserved, but updated to the latest
supported by clang rather than using abseil's older/deprecated ones.
- ACQUIRE_LOCK macro is gone since we don't pass mutexes by pointer into
locks anymore (WTF abseil).
- ReleasableLock is gone. Instead there are now some llarp::util helper
methods to obtain unique and/or shared locks:
- `auto lock = util::unique_lock(mutex);` gets an RAII-but-also
unlockable object (std::unique_lock<T>, with T inferred from
`mutex`).
- `auto lock = util::shared_lock(mutex);` gets an RAII shared (i.e.
"reader") lock of the mutex.
- `auto lock = util::unique_locks(mutex1, mutex2, mutex3);` can be
used to atomically lock multiple mutexes at once (returning a
tuple of the locks).
This are templated on the mutex which makes them a bit more flexible
than using a concrete type: they can be used for any type of lockable
mutex, not only util::Mutex. (Some of the code here uses them for
getting locks around a std::mutex). Until C++17, using the RAII types
is painfully verbose:
```C++
// pre-C++17 - needing to figure out the mutex type here is annoying:
std::unique_lock<util::Mutex> lock(mutex);
// pre-C++17 and even more verbose (but at least the type isn't needed):
std::unique_lock<decltype(mutex)> lock(mutex);
// our compromise:
auto lock = util::unique_lock(mutex);
// C++17:
std::unique_lock lock(mutex);
```
All of these functions will also warn (under gcc or clang) if you
discard the return value. You can also do fancy things like
`auto l = util::unique_lock(mutex, std::adopt_lock)` (which lets a
lock take over an already-locked mutex).
- metrics code is gone, which also removes a big pile of code that was
only used by metrics:
- llarp::util::Scheduler
- llarp::thread::TimerQueue
- llarp::util::Stopwatch
5 years ago
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// Clang thread safety analysis macros. Does nothing under non-clang compilers.
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// Enable thread safety attributes only with clang and libc++ (the latter
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// because we are using stl mutexes, which don't have the required annotations
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// under stdlibc++). The attributes can be safely erased when compiling with
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// other compilers.
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#if defined(__clang__) && defined(_LIBCPP_VERSION) && !defined(SWIG)
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De-abseil, part 2: mutex, locks, (most) time
- util::Mutex is now a std::shared_timed_mutex, which is capable of
exclusive and shared locks.
- util::Lock is still present as a std::lock_guard<util::Mutex>.
- the locking annotations are preserved, but updated to the latest
supported by clang rather than using abseil's older/deprecated ones.
- ACQUIRE_LOCK macro is gone since we don't pass mutexes by pointer into
locks anymore (WTF abseil).
- ReleasableLock is gone. Instead there are now some llarp::util helper
methods to obtain unique and/or shared locks:
- `auto lock = util::unique_lock(mutex);` gets an RAII-but-also
unlockable object (std::unique_lock<T>, with T inferred from
`mutex`).
- `auto lock = util::shared_lock(mutex);` gets an RAII shared (i.e.
"reader") lock of the mutex.
- `auto lock = util::unique_locks(mutex1, mutex2, mutex3);` can be
used to atomically lock multiple mutexes at once (returning a
tuple of the locks).
This are templated on the mutex which makes them a bit more flexible
than using a concrete type: they can be used for any type of lockable
mutex, not only util::Mutex. (Some of the code here uses them for
getting locks around a std::mutex). Until C++17, using the RAII types
is painfully verbose:
```C++
// pre-C++17 - needing to figure out the mutex type here is annoying:
std::unique_lock<util::Mutex> lock(mutex);
// pre-C++17 and even more verbose (but at least the type isn't needed):
std::unique_lock<decltype(mutex)> lock(mutex);
// our compromise:
auto lock = util::unique_lock(mutex);
// C++17:
std::unique_lock lock(mutex);
```
All of these functions will also warn (under gcc or clang) if you
discard the return value. You can also do fancy things like
`auto l = util::unique_lock(mutex, std::adopt_lock)` (which lets a
lock take over an already-locked mutex).
- metrics code is gone, which also removes a big pile of code that was
only used by metrics:
- llarp::util::Scheduler
- llarp::thread::TimerQueue
- llarp::util::Stopwatch
5 years ago
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#define THREAD_ANNOTATION_ATTRIBUTE__(x) __attribute__((x))
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#else
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#define THREAD_ANNOTATION_ATTRIBUTE__(x) // no-op
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#endif
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#define CAPABILITY(x) THREAD_ANNOTATION_ATTRIBUTE__(capability(x))
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#define SCOPED_CAPABILITY THREAD_ANNOTATION_ATTRIBUTE__(scoped_lockable)
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#define GUARDED_BY(x) THREAD_ANNOTATION_ATTRIBUTE__(guarded_by(x))
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#define PT_GUARDED_BY(x) THREAD_ANNOTATION_ATTRIBUTE__(pt_guarded_by(x))
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#define ACQUIRED_BEFORE(...) \
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THREAD_ANNOTATION_ATTRIBUTE__(acquired_before(__VA_ARGS__))
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#define ACQUIRED_AFTER(...) \
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THREAD_ANNOTATION_ATTRIBUTE__(acquired_after(__VA_ARGS__))
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#define REQUIRES(...) \
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THREAD_ANNOTATION_ATTRIBUTE__(requires_capability(__VA_ARGS__))
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#define REQUIRES_SHARED(...) \
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THREAD_ANNOTATION_ATTRIBUTE__(requires_shared_capability(__VA_ARGS__))
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#define ACQUIRE(...) \
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THREAD_ANNOTATION_ATTRIBUTE__(acquire_capability(__VA_ARGS__))
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#define ACQUIRE_SHARED(...) \
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THREAD_ANNOTATION_ATTRIBUTE__(acquire_shared_capability(__VA_ARGS__))
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#define RELEASE(...) \
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THREAD_ANNOTATION_ATTRIBUTE__(release_capability(__VA_ARGS__))
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#define RELEASE_SHARED(...) \
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THREAD_ANNOTATION_ATTRIBUTE__(release_shared_capability(__VA_ARGS__))
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#define TRY_ACQUIRE(...) \
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THREAD_ANNOTATION_ATTRIBUTE__(try_acquire_capability(__VA_ARGS__))
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#define TRY_ACQUIRE_SHARED(...) \
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THREAD_ANNOTATION_ATTRIBUTE__(try_acquire_shared_capability(__VA_ARGS__))
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#define EXCLUDES(...) THREAD_ANNOTATION_ATTRIBUTE__(locks_excluded(__VA_ARGS__))
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#define ASSERT_CAPABILITY(x) THREAD_ANNOTATION_ATTRIBUTE__(assert_capability(x))
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#define ASSERT_SHARED_CAPABILITY(x) \
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THREAD_ANNOTATION_ATTRIBUTE__(assert_shared_capability(x))
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#define RETURN_CAPABILITY(x) THREAD_ANNOTATION_ATTRIBUTE__(lock_returned(x))
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#define NO_THREAD_SAFETY_ANALYSIS \
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THREAD_ANNOTATION_ATTRIBUTE__(no_thread_safety_analysis)
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