mirror of
https://github.com/XRPLF/rippled.git
synced 2026-06-04 09:16:47 +00:00
90 lines
2.1 KiB
C++
90 lines
2.1 KiB
C++
/**
|
|
*
|
|
* TODO: Remove xrpl::basic_semaphore (and this file) and use
|
|
* std::counting_semaphore.
|
|
*
|
|
* Background:
|
|
* - PR: https://github.com/XRPLF/rippled/pull/5512/files
|
|
* - std::counting_semaphore had a bug fixed in both GCC and Clang:
|
|
* * GCC PR 104928: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104928
|
|
* * LLVM PR 79265: https://github.com/llvm/llvm-project/pull/79265
|
|
*
|
|
* GCC:
|
|
* According to GCC Bugzilla PR104928
|
|
* (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104928#c15), the fix is
|
|
* scheduled for inclusion in GCC 16.0 (see comment #15, Target
|
|
* Milestone: 16.0). It is not included in GCC 14.x or earlier, and there is no
|
|
* indication that it will be backported to GCC 13.x or 14.x branches.
|
|
*
|
|
* Clang:
|
|
* The fix for is included in Clang 19.1.0+
|
|
*
|
|
* Once the minimum compiler version is updated to > GCC 16.0 or Clang 19.1.0,
|
|
* we can remove this file.
|
|
*
|
|
* WARNING: Avoid using std::counting_semaphore until the minimum compiler
|
|
* version is updated.
|
|
*/
|
|
|
|
#pragma once
|
|
|
|
#include <condition_variable>
|
|
#include <mutex>
|
|
|
|
namespace xrpl {
|
|
|
|
template <class Mutex, class CondVar>
|
|
class BasicSemaphore
|
|
{
|
|
private:
|
|
Mutex mutex_;
|
|
CondVar cond_;
|
|
std::size_t count_;
|
|
|
|
public:
|
|
using size_type = std::size_t;
|
|
|
|
/** Create the semaphore, with an optional initial count.
|
|
If unspecified, the initial count is zero.
|
|
*/
|
|
explicit BasicSemaphore(size_type count = 0) : count_(count)
|
|
{
|
|
}
|
|
|
|
/** Increment the count and unblock one waiting thread. */
|
|
void
|
|
notify()
|
|
{
|
|
std::scoped_lock const lock{mutex_};
|
|
++count_;
|
|
cond_.notify_one();
|
|
}
|
|
|
|
/** Block until notify is called. */
|
|
void
|
|
wait()
|
|
{
|
|
std::unique_lock lock{mutex_};
|
|
while (count_ == 0)
|
|
cond_.wait(lock);
|
|
--count_;
|
|
}
|
|
|
|
/** Perform a non-blocking wait.
|
|
@return `true` If the wait would be satisfied.
|
|
*/
|
|
bool
|
|
tryWait()
|
|
{
|
|
std::scoped_lock lock{mutex_};
|
|
if (count_ == 0)
|
|
return false;
|
|
--count_;
|
|
return true;
|
|
}
|
|
};
|
|
|
|
using semaphore = BasicSemaphore<std::mutex, std::condition_variable>;
|
|
|
|
} // namespace xrpl
|