From f93074a43019927a6aefc607bcd77172f5a03e08 Mon Sep 17 00:00:00 2001
From: Pavel Roskin <plroskin@gmail.com>
Date: Sat, 23 Apr 2016 00:26:46 -0700
Subject: [PATCH] Add unnamed semaphore support on Mac OS

sem_init() is not functional on Mac OS. Use the Grand Central Dispatch
implementation.

Make libscp_lock.c use semaphores through the thread_calls wrapper.
---
 common/thread_calls.c       | 15 +++++++++++++++
 sesman/libscp/libscp_lock.c | 22 +++++++++++-----------
 2 files changed, 26 insertions(+), 11 deletions(-)

diff --git a/common/thread_calls.c b/common/thread_calls.c
index a68e902a..d828b353 100644
--- a/common/thread_calls.c
+++ b/common/thread_calls.c
@@ -20,6 +20,10 @@
 
 #if defined(_WIN32)
 #include <windows.h>
+#elif defined(__APPLE__)
+#include <pthread.h>
+#include <dispatch/dispatch.h>
+#include <dispatch/time.h>
 #else
 #include <pthread.h>
 #include <semaphore.h>
@@ -159,6 +163,9 @@ tc_sem_create(int init_count)
 
     sem = CreateSemaphore(0, init_count, init_count + 10, 0);
     return (tbus)sem;
+#elif defined(__APPLE__)
+    dispatch_semaphore_t sem = dispatch_semaphore_create(init_count);
+    return (tbus)sem;
 #else
     sem_t *sem = (sem_t *)NULL;
 
@@ -174,6 +181,8 @@ tc_sem_delete(tbus sem)
 {
 #if defined(_WIN32)
     CloseHandle((HANDLE)sem);
+#elif defined(__APPLE__)
+    dispatch_release((dispatch_semaphore_t)sem);
 #else
     sem_t *lsem;
 
@@ -190,6 +199,9 @@ tc_sem_dec(tbus sem)
 #if defined(_WIN32)
     WaitForSingleObject((HANDLE)sem, INFINITE);
     return 0;
+#elif defined(__APPLE__)
+    dispatch_semaphore_wait((dispatch_semaphore_t)sem, DISPATCH_TIME_FOREVER);
+    return 0;
 #else
     sem_wait((sem_t *)sem);
     return 0;
@@ -203,6 +215,9 @@ tc_sem_inc(tbus sem)
 #if defined(_WIN32)
     ReleaseSemaphore((HANDLE)sem, 1, 0);
     return 0;
+#elif defined(__APPLE__)
+    dispatch_semaphore_signal((dispatch_semaphore_t)sem);
+    return 0;
 #else
     sem_post((sem_t *)sem);
     return 0;
diff --git a/sesman/libscp/libscp_lock.c b/sesman/libscp/libscp_lock.c
index bd3ff771..848c1966 100644
--- a/sesman/libscp/libscp_lock.c
+++ b/sesman/libscp/libscp_lock.c
@@ -20,14 +20,14 @@
  */
 
 #include "libscp_lock.h"
+#include "thread_calls.h"
 
-#include <semaphore.h>
 #include <pthread.h>
 
 pthread_mutex_t lock_fork;            /* this lock protects the counters */
 pthread_mutexattr_t lock_fork_attr;   /* mutex attributes */
-sem_t lock_fork_req;                  /* semaphore on which the process that are going to fork suspend on */
-sem_t lock_fork_wait;                 /* semaphore on which the suspended process wait on */
+tbus lock_fork_req;                   /* semaphore on which the process that are going to fork suspend on */
+tbus lock_fork_wait;                  /* semaphore on which the suspended process wait on */
 int lock_fork_forkers_count;          /* threads that want to fork */
 int lock_fork_blockers_count;         /* threads thar are blocking fork */
 int lock_fork_waiting_count;          /* threads suspended until the fork finishes */
@@ -38,8 +38,8 @@ scp_lock_init(void)
     /* initializing fork lock */
     pthread_mutexattr_init(&lock_fork_attr);
     pthread_mutex_init(&lock_fork, &lock_fork_attr);
-    sem_init(&lock_fork_req, 0, 0);
-    sem_init(&lock_fork_wait, 0, 0);
+    lock_fork_req = tc_sem_create(0);
+    lock_fork_wait = tc_sem_create(0);
 
     /* here we don't use locking because lock_init() should be called BEFORE */
     /* any thread is created                                                 */
@@ -58,14 +58,14 @@ scp_lock_fork_request(void)
     if (lock_fork_blockers_count == 0)
     {
         /* if no one is blocking fork(), then we're allowed to fork */
-        sem_post(&lock_fork_req);
+        tc_sem_inc(lock_fork_req);
     }
 
     lock_fork_forkers_count++;
     pthread_mutex_unlock(&lock_fork);
 
     /* we wait to be allowed to fork() */
-    sem_wait(&lock_fork_req);
+    tc_sem_dec(lock_fork_req);
 }
 
 /******************************************************************************/
@@ -78,13 +78,13 @@ scp_lock_fork_release(void)
     /* if there's someone else that want to fork, we let him fork() */
     if (lock_fork_forkers_count > 0)
     {
-        sem_post(&lock_fork_req);
+        tc_sem_inc(lock_fork_req);
     }
 
     for (; lock_fork_waiting_count > 0; lock_fork_waiting_count--)
     {
         /* waking up the other processes */
-        sem_post(&lock_fork_wait);
+        tc_sem_inc(lock_fork_wait);
     }
 
     pthread_mutex_unlock(&lock_fork);
@@ -107,7 +107,7 @@ scp_lock_fork_critical_section_end(int blocking)
     /* then we let him go */
     if ((lock_fork_blockers_count == 0) && (lock_fork_forkers_count > 0))
     {
-        sem_post(&lock_fork_req);
+        tc_sem_inc(lock_fork_req);
     }
 
     pthread_mutex_unlock(&lock_fork);
@@ -129,7 +129,7 @@ scp_lock_fork_critical_section_start(void)
             pthread_mutex_unlock(&lock_fork);
 
             /* we wait until the fork finishes */
-            sem_wait(&lock_fork_wait);
+            tc_sem_dec(lock_fork_wait);
 
         }
         else