1 files changed, 167 insertions, 0 deletions
diff --git a/abseil-cpp/absl/synchronization/internal/pthread_waiter.cc b/abseil-cpp/absl/synchronization/internal/pthread_waiter.cc
new file mode 100644
index 0000000..bf700e9
--- /dev/null
+++ b/abseil-cpp/absl/synchronization/internal/pthread_waiter.cc
@@ -0,0 +1,167 @@
+// Copyright 2023 The Abseil Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "absl/synchronization/internal/pthread_waiter.h"
+
+#ifdef ABSL_INTERNAL_HAVE_PTHREAD_WAITER
+
+#include <pthread.h>
+#include <sys/time.h>
+#include <unistd.h>
+
+#include <cassert>
+#include <cerrno>
+
+#include "absl/base/config.h"
+#include "absl/base/internal/raw_logging.h"
+#include "absl/base/internal/thread_identity.h"
+#include "absl/base/optimization.h"
+#include "absl/synchronization/internal/kernel_timeout.h"
+
+namespace absl {
+ABSL_NAMESPACE_BEGIN
+namespace synchronization_internal {
+
+namespace {
+class PthreadMutexHolder {
+ public:
+  explicit PthreadMutexHolder(pthread_mutex_t *mu) : mu_(mu) {
+    const int err = pthread_mutex_lock(mu_);
+    if (err != 0) {
+      ABSL_RAW_LOG(FATAL, "pthread_mutex_lock failed: %d", err);
+    }
+  }
+
+  PthreadMutexHolder(const PthreadMutexHolder &rhs) = delete;
+  PthreadMutexHolder &operator=(const PthreadMutexHolder &rhs) = delete;
+
+  ~PthreadMutexHolder() {
+    const int err = pthread_mutex_unlock(mu_);
+    if (err != 0) {
+      ABSL_RAW_LOG(FATAL, "pthread_mutex_unlock failed: %d", err);
+    }
+  }
+
+ private:
+  pthread_mutex_t *mu_;
+};
+}  // namespace
+
+#ifdef ABSL_INTERNAL_NEED_REDUNDANT_CONSTEXPR_DECL
+constexpr char PthreadWaiter::kName[];
+#endif
+
+PthreadWaiter::PthreadWaiter() : waiter_count_(0), wakeup_count_(0) {
+  const int err = pthread_mutex_init(&mu_, 0);
+  if (err != 0) {
+    ABSL_RAW_LOG(FATAL, "pthread_mutex_init failed: %d", err);
+  }
+
+  const int err2 = pthread_cond_init(&cv_, 0);
+  if (err2 != 0) {
+    ABSL_RAW_LOG(FATAL, "pthread_cond_init failed: %d", err2);
+  }
+}
+
+#ifdef __APPLE__
+#define ABSL_INTERNAL_HAS_PTHREAD_COND_TIMEDWAIT_RELATIVE_NP 1
+#endif
+
+#if defined(__GLIBC__) && \
+    (__GLIBC__ > 2 || (__GLIBC__ == 2 && __GLIBC_MINOR__ >= 30))
+#define ABSL_INTERNAL_HAVE_PTHREAD_COND_CLOCKWAIT 1
+#elif defined(__ANDROID_API__) && __ANDROID_API__ >= 30
+#define ABSL_INTERNAL_HAVE_PTHREAD_COND_CLOCKWAIT 1
+#endif
+
+// Calls pthread_cond_timedwait() or possibly something else like
+// pthread_cond_timedwait_relative_np() depending on the platform and
+// KernelTimeout requested. The return value is the same as the return
+// value of pthread_cond_timedwait().
+int PthreadWaiter::TimedWait(KernelTimeout t) {
+  assert(t.has_timeout());
+  if (KernelTimeout::SupportsSteadyClock() && t.is_relative_timeout()) {
+#ifdef ABSL_INTERNAL_HAS_PTHREAD_COND_TIMEDWAIT_RELATIVE_NP
+    const auto rel_timeout = t.MakeRelativeTimespec();
+    return pthread_cond_timedwait_relative_np(&cv_, &mu_, &rel_timeout);
+#elif defined(ABSL_INTERNAL_HAVE_PTHREAD_COND_CLOCKWAIT) && \
+    defined(CLOCK_MONOTONIC)
+    const auto abs_clock_timeout = t.MakeClockAbsoluteTimespec(CLOCK_MONOTONIC);
+    return pthread_cond_clockwait(&cv_, &mu_, CLOCK_MONOTONIC,
+                                  &abs_clock_timeout);
+#endif
+  }
+
+  const auto abs_timeout = t.MakeAbsTimespec();
+  return pthread_cond_timedwait(&cv_, &mu_, &abs_timeout);
+}
+
+bool PthreadWaiter::Wait(KernelTimeout t) {
+  PthreadMutexHolder h(&mu_);
+  ++waiter_count_;
+  // Loop until we find a wakeup to consume or timeout.
+  // Note that, since the thread ticker is just reset, we don't need to check
+  // whether the thread is idle on the very first pass of the loop.
+  bool first_pass = true;
+  while (wakeup_count_ == 0) {
+    if (!first_pass) MaybeBecomeIdle();
+    // No wakeups available, time to wait.
+    if (!t.has_timeout()) {
+      const int err = pthread_cond_wait(&cv_, &mu_);
+      if (err != 0) {
+        ABSL_RAW_LOG(FATAL, "pthread_cond_wait failed: %d", err);
+      }
+    } else {
+      const int err = TimedWait(t);
+      if (err == ETIMEDOUT) {
+        --waiter_count_;
+        return false;
+      }
+      if (err != 0) {
+        ABSL_RAW_LOG(FATAL, "PthreadWaiter::TimedWait() failed: %d", err);
+      }
+    }
+    first_pass = false;
+  }
+  // Consume a wakeup and we're done.
+  --wakeup_count_;
+  --waiter_count_;
+  return true;
+}
+
+void PthreadWaiter::Post() {
+  PthreadMutexHolder h(&mu_);
+  ++wakeup_count_;
+  InternalCondVarPoke();
+}
+
+void PthreadWaiter::Poke() {
+  PthreadMutexHolder h(&mu_);
+  InternalCondVarPoke();
+}
+
+void PthreadWaiter::InternalCondVarPoke() {
+  if (waiter_count_ != 0) {
+    const int err = pthread_cond_signal(&cv_);
+    if (ABSL_PREDICT_FALSE(err != 0)) {
+      ABSL_RAW_LOG(FATAL, "pthread_cond_signal failed: %d", err);
+    }
+  }
+}
+
+}  // namespace synchronization_internal
+ABSL_NAMESPACE_END
+}  // namespace absl
+
+#endif  // ABSL_INTERNAL_HAVE_PTHREAD_WAITER