mirror of
https://github.com/oxen-io/lokinet.git
synced 2024-11-03 23:15:52 +00:00
b4440094b0
- 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:🧵:TimerQueue
- llarp::util::Stopwatch
47 lines
1.0 KiB
C++
47 lines
1.0 KiB
C++
#pragma once
|
|
#include <mutex>
|
|
#include <condition_variable>
|
|
|
|
namespace llarp
|
|
{
|
|
namespace util
|
|
{
|
|
/// Barrier class that blocks all threads until the high water mark of
|
|
/// threads (set during construction) is reached, then releases them all.
|
|
class Barrier
|
|
{
|
|
std::mutex mutex;
|
|
std::condition_variable cv;
|
|
unsigned pending;
|
|
|
|
public:
|
|
Barrier(unsigned threads) : pending{threads}
|
|
{
|
|
}
|
|
|
|
/// Returns true if *this* Block call is the one that releases all of
|
|
/// them; returns false (i.e. after unblocking) if some other thread
|
|
/// triggered the released.
|
|
bool
|
|
Block()
|
|
{
|
|
std::unique_lock< std::mutex > lock{mutex};
|
|
if(pending == 1)
|
|
{
|
|
pending = 0;
|
|
lock.unlock();
|
|
cv.notify_all();
|
|
return true;
|
|
}
|
|
else if(pending > 1)
|
|
{
|
|
pending--;
|
|
}
|
|
cv.wait(lock, [this] { return !pending; });
|
|
return false;
|
|
}
|
|
};
|
|
|
|
} // namespace util
|
|
} // namespace llarp
|