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include/asio/detail/posix_event.hpp

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+//
+// detail/posix_event.hpp
+// ~~~~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2025 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef ASIO_DETAIL_POSIX_EVENT_HPP
+#define ASIO_DETAIL_POSIX_EVENT_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include "asio/detail/config.hpp"
+
+#if defined(ASIO_HAS_PTHREADS)
+
+#include <cstddef>
+#include <pthread.h>
+#include "asio/detail/assert.hpp"
+#include "asio/detail/noncopyable.hpp"
+
+#include "asio/detail/push_options.hpp"
+
+namespace asio {
+namespace detail {
+
+class posix_event
+  : private noncopyable
+{
+public:
+  // Constructor.
+  ASIO_DECL posix_event();
+
+  // Destructor.
+  ~posix_event()
+  {
+    ::pthread_cond_destroy(&cond_);
+  }
+
+  // Signal the event. (Retained for backward compatibility.)
+  template <typename Lock>
+  void signal(Lock& lock)
+  {
+    this->signal_all(lock);
+  }
+
+  // Signal all waiters.
+  template <typename Lock>
+  void signal_all(Lock& lock)
+  {
+    ASIO_ASSERT(lock.locked());
+    (void)lock;
+    state_ |= 1;
+    ::pthread_cond_broadcast(&cond_); // Ignore EINVAL.
+  }
+
+  // Unlock the mutex and signal one waiter.
+  template <typename Lock>
+  void unlock_and_signal_one(Lock& lock)
+  {
+    ASIO_ASSERT(lock.locked());
+    state_ |= 1;
+    bool have_waiters = (state_ > 1);
+    lock.unlock();
+    if (have_waiters)
+      ::pthread_cond_signal(&cond_); // Ignore EINVAL.
+  }
+
+  // Unlock the mutex and signal one waiter who may destroy us.
+  template <typename Lock>
+  void unlock_and_signal_one_for_destruction(Lock& lock)
+  {
+    ASIO_ASSERT(lock.locked());
+    state_ |= 1;
+    bool have_waiters = (state_ > 1);
+    if (have_waiters)
+      ::pthread_cond_signal(&cond_); // Ignore EINVAL.
+    lock.unlock();
+  }
+
+  // If there's a waiter, unlock the mutex and signal it.
+  template <typename Lock>
+  bool maybe_unlock_and_signal_one(Lock& lock)
+  {
+    ASIO_ASSERT(lock.locked());
+    state_ |= 1;
+    if (state_ > 1)
+    {
+      lock.unlock();
+      ::pthread_cond_signal(&cond_); // Ignore EINVAL.
+      return true;
+    }
+    return false;
+  }
+
+  // Reset the event.
+  template <typename Lock>
+  void clear(Lock& lock)
+  {
+    ASIO_ASSERT(lock.locked());
+    (void)lock;
+    state_ &= ~std::size_t(1);
+  }
+
+  // Wait for the event to become signalled.
+  template <typename Lock>
+  void wait(Lock& lock)
+  {
+    ASIO_ASSERT(lock.locked());
+    while ((state_ & 1) == 0)
+    {
+      state_ += 2;
+      ::pthread_cond_wait(&cond_, &lock.mutex().mutex_); // Ignore EINVAL.
+      state_ -= 2;
+    }
+  }
+
+  // Timed wait for the event to become signalled.
+  template <typename Lock>
+  bool wait_for_usec(Lock& lock, long usec)
+  {
+    ASIO_ASSERT(lock.locked());
+    if ((state_ & 1) == 0)
+    {
+      state_ += 2;
+      timespec ts;
+#if (defined(__MACH__) && defined(__APPLE__)) \
+      || (defined(__ANDROID__) && (__ANDROID_API__ < 21) \
+          && defined(HAVE_PTHREAD_COND_TIMEDWAIT_RELATIVE))
+      ts.tv_sec = usec / 1000000;
+      ts.tv_nsec = (usec % 1000000) * 1000;
+      ::pthread_cond_timedwait_relative_np(
+          &cond_, &lock.mutex().mutex_, &ts); // Ignore EINVAL.
+#else // (defined(__MACH__) && defined(__APPLE__))
+      // || (defined(__ANDROID__) && (__ANDROID_API__ < 21)
+      //     && defined(HAVE_PTHREAD_COND_TIMEDWAIT_RELATIVE))
+      if (::clock_gettime(CLOCK_MONOTONIC, &ts) == 0)
+      {
+        ts.tv_sec += usec / 1000000;
+        ts.tv_nsec += (usec % 1000000) * 1000;
+        ts.tv_sec += ts.tv_nsec / 1000000000;
+        ts.tv_nsec = ts.tv_nsec % 1000000000;
+        ::pthread_cond_timedwait(&cond_,
+            &lock.mutex().mutex_, &ts); // Ignore EINVAL.
+      }
+#endif // (defined(__MACH__) && defined(__APPLE__))
+       // || (defined(__ANDROID__) && (__ANDROID_API__ < 21)
+       //     && defined(HAVE_PTHREAD_COND_TIMEDWAIT_RELATIVE))
+      state_ -= 2;
+    }
+    return (state_ & 1) != 0;
+  }
+
+private:
+  ::pthread_cond_t cond_;
+  std::size_t state_;
+};
+
+} // namespace detail
+} // namespace asio
+
+#include "asio/detail/pop_options.hpp"
+
+#if defined(ASIO_HEADER_ONLY)
+# include "asio/detail/impl/posix_event.ipp"
+#endif // defined(ASIO_HEADER_ONLY)
+
+#endif // defined(ASIO_HAS_PTHREADS)
+
+#endif // ASIO_DETAIL_POSIX_EVENT_HPP