unix, windows: add semaphore functions

include/uv-private/uv-unix.h

@@ -35,6 +35,8 @@
 #include <netdb.h>
 #include <pwd.h>
 #include <termios.h>
+
+#include <semaphore.h>
 #include <pthread.h>
 
 #if __sun
@@ -58,6 +60,7 @@ typedef pthread_once_t uv_once_t;
 typedef pthread_t uv_thread_t;
 typedef pthread_mutex_t uv_mutex_t;
 typedef pthread_rwlock_t uv_rwlock_t;
+typedef sem_t uv_sem_t;
 
 /* Platform-specific definitions for uv_spawn support. */
 typedef gid_t uv_gid_t;

include/uv-private/uv-win.h

@@ -169,6 +169,8 @@ typedef SOCKET uv_os_sock_t;
 
 typedef HANDLE uv_thread_t;
 
+typedef HANDLE uv_sem_t;
+
 typedef CRITICAL_SECTION uv_mutex_t;
 
 typedef union {

include/uv.h

@@ -1624,6 +1624,15 @@ UV_EXTERN void uv_rwlock_wrlock(uv_rwlock_t* rwlock);
 UV_EXTERN int uv_rwlock_trywrlock(uv_rwlock_t* rwlock);
 UV_EXTERN void uv_rwlock_wrunlock(uv_rwlock_t* rwlock);
 
+/*
+ * Same goes for the semaphore functions.
+ */
+UV_EXTERN int uv_sem_init(uv_sem_t* sem, unsigned int value);
+UV_EXTERN void uv_sem_destroy(uv_sem_t* sem);
+UV_EXTERN void uv_sem_post(uv_sem_t* sem);
+UV_EXTERN void uv_sem_wait(uv_sem_t* sem);
+UV_EXTERN int uv_sem_trywait(uv_sem_t* sem);
+
 /* Runs a function once and only once. Concurrent calls to uv_once() with the
  * same guard will block all callers except one (it's unspecified which one).
  * The guard should be initialized statically with the UV_ONCE_INIT macro.

src/unix/thread.c

@@ -166,3 +166,46 @@ void uv_once(uv_once_t* guard, void (*callback)(void)) {
   if (pthread_once(guard, callback))
     abort();
 }
+
+
+int uv_sem_init(uv_sem_t* sem, unsigned int value) {
+  return sem_init(sem, 0, value);
+}
+
+
+void uv_sem_destroy(uv_sem_t* sem) {
+  if (sem_destroy(sem))
+    abort();
+}
+
+
+void uv_sem_post(uv_sem_t* sem) {
+  if (sem_post(sem))
+    abort();
+}
+
+
+void uv_sem_wait(uv_sem_t* sem) {
+  int r;
+
+  do
+    r = sem_wait(sem);
+  while (r == -1 && errno == EINTR);
+
+  if (r)
+    abort();
+}
+
+
+int uv_sem_trywait(uv_sem_t* sem) {
+  int r;
+
+  do
+    r = sem_trywait(sem);
+  while (r == -1 && errno == EINTR);
+
+  if (r && errno != EAGAIN)
+    abort();
+
+  return r;
+}

src/win/thread.c

@@ -20,6 +20,7 @@
  */
 
 #include <assert.h>
+#include <limits.h>
 
 #include "uv.h"
 #include "internal.h"
@@ -207,6 +208,43 @@ void uv_rwlock_wrunlock(uv_rwlock_t* rwlock) {
 }
 
 
+int uv_sem_init(uv_sem_t* sem, unsigned int value) {
+  *sem = CreateSemaphore(NULL, value, INT_MAX, NULL);
+  return *sem ? 0 : -1;
+}
+
+
+void uv_sem_destroy(uv_sem_t* sem) {
+  if (!CloseHandle(*sem))
+    abort();
+}
+
+
+void uv_sem_post(uv_sem_t* sem) {
+  if (!ReleaseSemaphore(*sem, 1, NULL))
+    abort();
+}
+
+
+void uv_sem_wait(uv_sem_t* sem) {
+  if (WaitForSingleObject(*sem, INFINITE) != WAIT_OBJECT_0)
+    abort();
+}
+
+
+int uv_sem_trywait(uv_sem_t* sem) {
+  DWORD r = WaitForSingleObject(*sem, 0);
+
+  if (r == WAIT_OBJECT_0)
+    return 0;
+
+  if (r == WAIT_TIMEOUT)
+    return -1;
+
+  abort();
+}
+
+
 inline static int uv__rwlock_srwlock_init(uv_rwlock_t* rwlock) {
   pInitializeSRWLock(&rwlock->srwlock_);
   return 0;

test/test-list.h

@@ -22,6 +22,9 @@
 TEST_DECLARE   (platform_output)
 TEST_DECLARE   (callback_order)
 TEST_DECLARE   (run_once)
+TEST_DECLARE   (semaphore_1)
+TEST_DECLARE   (semaphore_2)
+TEST_DECLARE   (semaphore_3)
 TEST_DECLARE   (tty)
 TEST_DECLARE   (stdio_over_pipes)
 TEST_DECLARE   (ipc_listen_before_write)
@@ -193,6 +196,9 @@ TASK_LIST_START
   TEST_ENTRY  (callback_order)
 #endif
   TEST_ENTRY  (run_once)
+  TEST_ENTRY  (semaphore_1)
+  TEST_ENTRY  (semaphore_2)
+  TEST_ENTRY  (semaphore_3)
 
   TEST_ENTRY  (pipe_connect_bad_name)
   TEST_ENTRY  (pipe_connect_to_file)

test/test-semaphore.c

@@ -0,0 +1,111 @@
+/* Copyright Joyent, Inc. and other Node contributors. All rights reserved.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to
+ * deal in the Software without restriction, including without limitation the
+ * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+ * sell copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+
+#include "uv.h"
+#include "task.h"
+
+#include <stdlib.h>
+#include <string.h>
+
+typedef struct {
+  uv_mutex_t mutex;
+  uv_sem_t sem;
+  int delay;
+  volatile int posted;
+} worker_config;
+
+
+static void worker(void* arg) {
+  worker_config* c = arg;
+
+  if (c->delay)
+    uv_sleep(c->delay);
+
+  uv_mutex_lock(&c->mutex);
+  ASSERT(c->posted == 0);
+  uv_sem_post(&c->sem);
+  c->posted = 1;
+  uv_mutex_unlock(&c->mutex);
+}
+
+
+TEST_IMPL(semaphore_1) {
+  uv_thread_t thread;
+  worker_config wc;
+
+  memset(&wc, 0, sizeof(wc));
+
+  ASSERT(0 == uv_sem_init(&wc.sem, 0));
+  ASSERT(0 == uv_mutex_init(&wc.mutex));
+  ASSERT(0 == uv_thread_create(&thread, worker, &wc));
+
+  uv_sleep(100);
+  uv_mutex_lock(&wc.mutex);
+  ASSERT(wc.posted == 1);
+  uv_sem_wait(&wc.sem); /* should not block */
+  uv_mutex_unlock(&wc.mutex); /* ergo, it should be ok to unlock after wait */
+
+  ASSERT(0 == uv_thread_join(&thread));
+  uv_mutex_destroy(&wc.mutex);
+  uv_sem_destroy(&wc.sem);
+
+  return 0;
+}
+
+
+TEST_IMPL(semaphore_2) {
+  uv_thread_t thread;
+  worker_config wc;
+
+  memset(&wc, 0, sizeof(wc));
+  wc.delay = 100;
+
+  ASSERT(0 == uv_sem_init(&wc.sem, 0));
+  ASSERT(0 == uv_mutex_init(&wc.mutex));
+  ASSERT(0 == uv_thread_create(&thread, worker, &wc));
+
+  uv_sem_wait(&wc.sem);
+
+  ASSERT(0 == uv_thread_join(&thread));
+  uv_mutex_destroy(&wc.mutex);
+  uv_sem_destroy(&wc.sem);
+
+  return 0;
+}
+
+
+TEST_IMPL(semaphore_3) {
+  uv_sem_t sem;
+
+  ASSERT(0 == uv_sem_init(&sem, 3));
+  uv_sem_wait(&sem); /* should not block */
+  uv_sem_wait(&sem); /* should not block */
+  ASSERT(0 == uv_sem_trywait(&sem));
+  ASSERT(-1 == uv_sem_trywait(&sem));
+
+  uv_sem_post(&sem);
+  ASSERT(0 == uv_sem_trywait(&sem));
+  ASSERT(-1 == uv_sem_trywait(&sem));
+
+  uv_sem_destroy(&sem);
+
+  return 0;
+}

uv.gyp

@@ -333,6 +333,7 @@
         'test/test-process-title.c',
         'test/test-ref.c',
         'test/test-run-once.c',
+        'test/test-semaphore.c',
         'test/test-shutdown-close.c',
         'test/test-shutdown-eof.c',
         'test/test-spawn.c',