Make psemaphore similar to C++20 std::counting_semaphore (#2569)

src/curl.h

@@ -34,6 +34,7 @@
 #include "common.h"
 #include "fdcache_page.h"
 #include "metaheader.h"
+#include "psemaphore.h"
 #include "s3fs_util.h"
 #include "types.h"
 
@@ -86,7 +87,6 @@ typedef std::unique_ptr<CURL, decltype(&curl_easy_cleanup)> CurlUniquePtr;
 class CurlHandlerPool;
 class S3fsCred;
 class S3fsCurl;
-class Semaphore;
 
 // Prototype function for lazy setup options for curl handle
 typedef bool (*s3fscurl_lazy_setup)(S3fsCurl* s3fscurl);

src/curl_multi.cpp

@@ -119,7 +119,8 @@ int S3fsMultiCurl::MultiPerform()
     std::map<std::thread::id, std::pair<std::thread, std::future<int>>> threads;
     int                      result = 0;
     bool                     isMultiHead = false;
-    Semaphore                sem(GetMaxParallelism());
+    int                      semCount = GetMaxParallelism();
+    Semaphore                sem(semCount);
 
     for(auto iter = clist_req.cbegin(); iter != clist_req.cend(); ++iter) {
         S3fsCurl*   s3fscurl = iter->get();
@@ -127,7 +128,7 @@ int S3fsMultiCurl::MultiPerform()
             continue;
         }
 
-        sem.wait();
+        sem.acquire();
 
         {
             const std::lock_guard<std::mutex> lock(completed_tids_lock);
@@ -155,8 +156,8 @@ int S3fsMultiCurl::MultiPerform()
         threads.emplace(std::piecewise_construct, std::forward_as_tuple(thread_id), std::forward_as_tuple(std::move(thread), std::move(future)));
     }
 
-    for(int i = 0; i < sem.get_value(); ++i){
+    for(int i = 0; i < semCount; ++i){
-        sem.wait();
+        sem.acquire();
     }
 
     const std::lock_guard<std::mutex> lock(completed_tids_lock);
@@ -355,7 +356,7 @@ void S3fsMultiCurl::RequestPerformWrapper(S3fsCurl* s3fscurl, std::promise<int>
 
     const std::lock_guard<std::mutex> lock(*s3fscurl->completed_tids_lock);
     s3fscurl->completed_tids->push_back(std::this_thread::get_id());
-    s3fscurl->sem->post();
+    s3fscurl->sem->release();
 
     promise.set_value(result);
 }

src/fdcache_fdinfo.cpp

@@ -646,7 +646,7 @@ int PseudoFdInfo::WaitAllThreadsExit()
 
     while(is_loop){
         // need to wait the worker exiting
-        uploaded_sem.wait();
+        uploaded_sem.acquire();
         {
             const std::lock_guard<std::mutex> lock(upload_list_lock);
             if(0 < completed_count){

src/psemaphore.h

@@ -24,6 +24,13 @@
 //-------------------------------------------------------------------
 // Class Semaphore
 //-------------------------------------------------------------------
+#if __cplusplus >= 202002L
+
+#include <semaphore>
+typedef std::counting_semaphore<INT_MAX> Semaphore;
+
+#else
+
 // portability wrapper for sem_t since macOS does not implement it
 #ifdef __APPLE__
 
@@ -36,8 +43,8 @@ class Semaphore
         ~Semaphore()
         {
             // macOS cannot destroy a semaphore with posts less than the initializer
-            for(int i = 0; i < get_value(); ++i){
+            for(int i = 0; i < value; ++i){
-                post();
+                release();
             }
             dispatch_release(sem);
         }
@@ -46,8 +53,8 @@ class Semaphore
         Semaphore& operator=(const Semaphore&) = delete;
         Semaphore& operator=(Semaphore&&) = delete;
 
-        void wait() { dispatch_semaphore_wait(sem, DISPATCH_TIME_FOREVER); }
+        void acquire() { dispatch_semaphore_wait(sem, DISPATCH_TIME_FOREVER); }
-        bool try_wait()
+        bool try_acquire()
         {
             if(0 == dispatch_semaphore_wait(sem, DISPATCH_TIME_NOW)){
                 return true;
@@ -55,8 +62,7 @@ class Semaphore
                 return false;
             }
         }
-        void post() { dispatch_semaphore_signal(sem); }
+        void release() { dispatch_semaphore_signal(sem); }
-        int get_value() const { return value; }
 
     private:
         int value;
@@ -71,16 +77,16 @@ class Semaphore
 class Semaphore
 {
     public:
-        explicit Semaphore(int value) : value(value) { sem_init(&mutex, 0, value); }
+        explicit Semaphore(int value) { sem_init(&mutex, 0, value); }
         ~Semaphore() { sem_destroy(&mutex); }
-        void wait()
+        void acquire()
         {
             int r;
             do {
                 r = sem_wait(&mutex);
             } while (r == -1 && errno == EINTR);
         }
-        bool try_wait()
+        bool try_acquire()
         {
             int result;
             do{
@@ -89,16 +95,16 @@ class Semaphore
 
             return (0 == result);
         }
-        void post() { sem_post(&mutex); }
+        void release() { sem_post(&mutex); }
-        int get_value() const { return value; }
 
     private:
-        int value;
         sem_t mutex;
 };
 
 #endif
 
+#endif
+
 #endif // S3FS_SEMAPHORE_H_
 
 /*

src/sighandlers.cpp

@@ -100,12 +100,12 @@ void S3fsSignals::CheckCacheWorker(Semaphore* pSem)
     // wait and loop
     while(S3fsSignals::enableUsr1){
         // wait
-        pSem->wait();
+        pSem->acquire();
 
         // cppcheck-suppress unmatchedSuppression
         // cppcheck-suppress knownConditionTrueFalse
         if(!S3fsSignals::enableUsr1){
-            break;    // assap
+            break;  // asap
         }
 
         // check all cache
@@ -114,7 +114,7 @@ void S3fsSignals::CheckCacheWorker(Semaphore* pSem)
         }
 
         // do not allow request queuing
-        while(pSem->try_wait());
+        while(pSem->try_acquire());
     }
 }
 
@@ -219,7 +219,7 @@ bool S3fsSignals::DestroyUsr1Handler()
     S3fsSignals::enableUsr1 = false;
 
     // wakeup thread
-    pSemUsr1->post();
+    pSemUsr1->release();
 
     // wait for thread exiting
     pThreadUsr1->join();
@@ -235,7 +235,7 @@ bool S3fsSignals::WakeupUsr1Thread()
         S3FS_PRN_ERR("The thread for SIGUSR1 is not setup.");
         return false;
     }
-    pSemUsr1->post();
+    pSemUsr1->release();
     return true;
 }
 

src/sighandlers.h

@@ -24,7 +24,7 @@
 #include <memory>
 #include <thread>
 
-class Semaphore;
+#include "psemaphore.h"
 
 //----------------------------------------------
 // class S3fsSignals

src/threadpoolman.cpp

@@ -76,7 +76,7 @@ void ThreadPoolMan::Worker(ThreadPoolMan* psingleton, std::promise<int> promise)
 
     while(!psingleton->IsExit()){
         // wait
-        psingleton->thpoolman_sem.wait();
+        psingleton->thpoolman_sem.acquire();
 
         if(psingleton->IsExit()){
             break;
@@ -101,7 +101,7 @@ void ThreadPoolMan::Worker(ThreadPoolMan* psingleton, std::promise<int> promise)
             S3FS_PRN_WARN("The instruction function returned with something error code(%ld).", reinterpret_cast<long>(retval));
         }
         if(param.psem){
-            param.psem->post();
+            param.psem->release();
         }
     }
 
@@ -156,7 +156,7 @@ bool ThreadPoolMan::StopThreads()
     // all threads to exit
     SetExitFlag(true);
     for(size_t waitcnt = thread_list.size(); 0 < waitcnt; --waitcnt){
-        thpoolman_sem.post();
+        thpoolman_sem.release();
     }
 
     // wait for threads exiting
@@ -168,7 +168,7 @@ bool ThreadPoolMan::StopThreads()
     thread_list.clear();
 
     // reset semaphore(to zero)
-    while(thpoolman_sem.try_wait()){
+    while(thpoolman_sem.try_acquire()){
     }
 
     return true;
@@ -212,7 +212,7 @@ void ThreadPoolMan::SetInstruction(const thpoolman_param& param)
     }
 
     // run thread
-    thpoolman_sem.post();
+    thpoolman_sem.release();
 }
 
 /*