implement waiter_linux.h

src/platform/waiter_linux.h

@@ -1,32 +1,106 @@
 #pragma once
 
+#include <pthread.h>
+
+#include <cstring>
+#include <atomic>
+#include <memory>
+#include <type_traits>
+
+namespace std {
+
+// deduction guides for std::unique_ptr
+template <typename T, typename D>
+unique_ptr(T* p, D&& d) -> unique_ptr<T, std::decay_t<D>>;
+
+} // namespace std
+
 namespace ipc {
 namespace detail {
 
 class waiter {
+    pthread_mutex_t       mutex_ = PTHREAD_MUTEX_INITIALIZER;
+    pthread_cond_t        cond_  = PTHREAD_COND_INITIALIZER;
+    std::atomic<unsigned> counter_ { 0 };
+
 public:
     using handle_t = void*;
 
+private:
+    constexpr static waiter* waiter_cast(handle_t h) {
+        return static_cast<waiter*>(h);
+    }
+
+public:
     constexpr static handle_t invalid() {
         return nullptr;
     }
 
     handle_t open(char const * name) {
         if (name == nullptr || name[0] == '\0') return invalid();
+        if (counter_.fetch_add(1, std::memory_order_acq_rel) == 0) {
+            // init mutex
+            pthread_mutexattr_t mutex_attr;
+            if (::pthread_mutexattr_init(&mutex_attr) != 0) {
                 return invalid();
             }
-
-    static void close(handle_t /*h*/) {
+            [[maybe_unused]] auto guard_mutex_attr = std::unique_ptr { &mutex_attr, ::pthread_mutexattr_destroy };
+            if (::pthread_mutexattr_setpshared(&mutex_attr, PTHREAD_PROCESS_SHARED) != 0) {
+                return invalid();
+            }
+            if (::pthread_mutex_init(&mutex_, &mutex_attr) != 0) {
+                return invalid();
+            }
+            auto guard_mutex = std::unique_ptr { &mutex_, ::pthread_mutex_destroy };
+            // init condition
+            pthread_condattr_t cond_attr;
+            if (::pthread_condattr_init(&cond_attr) != 0) {
+                return invalid();
+            }
+            [[maybe_unused]] auto guard_cond_attr = std::unique_ptr { &cond_attr, ::pthread_condattr_destroy };
+            if (::pthread_condattr_setpshared(&cond_attr, PTHREAD_PROCESS_SHARED) != 0) {
+                return invalid();
+            }
+            if (::pthread_cond_init(&cond_, &cond_attr) != 0) {
+                return invalid();
+            }
+            // no need to guard condition
+            // release guards
+            guard_mutex.release();
+        }
+        return this;
     }
 
-    bool wait(handle_t /*h*/) {
+    void close(handle_t h) {
+        if (h == invalid()) return;
+        auto w = waiter_cast(h);
+        if (w->counter_.fetch_sub(1, std::memory_order_acq_rel) == 1) {
+            ::pthread_cond_destroy (&(w->cond_ ));
+            ::pthread_mutex_destroy(&(w->mutex_));
+        }
+    }
+
+    bool wait(handle_t h) {
+        if (h == invalid()) return false;
+        auto w = waiter_cast(h);
+        if (::pthread_mutex_lock(&(w->mutex_)) != 0) {
             return false;
         }
-
-    void notify(handle_t /*h*/) {
+        [[maybe_unused]] auto guard = std::unique_ptr { &(w->mutex_), ::pthread_mutex_unlock };
+        if (::pthread_cond_wait(&(w->cond_), &(w->mutex_)) != 0) {
+            return false;
+        }
+        return true;
     }
 
-    void broadcast(handle_t /*h*/) {
+    void notify(handle_t h) {
+        if (h == invalid()) return;
+        ::pthread_cond_signal(&(waiter_cast(h)->cond_));
+    }
+
+    void broadcast(handle_t h) {
+        if (h == invalid()) return;
+        ::pthread_cond_broadcast(&(waiter_cast(h)->cond_));
     }
 };
 

src/platform/waiter_win.h

@@ -27,7 +27,7 @@ public:
         return ::CreateSemaphore(NULL, 0, LONG_MAX, ipc::detail::to_tchar(name).c_str());
     }
 
-    static void close(handle_t h) {
+    void close(handle_t h) {
         ::CloseHandle(h);
     }