cwThread.cpp : Made stateId and doFlags atomic.

cwThread.cpp

@@ -21,10 +21,12 @@ namespace cw
     typedef struct thread_str
     {
       pthread_t pThreadH;
-      stateId_t stateId;
+      
+      std::atomic<stateId_t> stateId;
+      std::atomic<unsigned>  doFlags;
+      
       cbFunc_t  func;
       void*     funcArg;
-      unsigned  doFlags;
       unsigned  stateMicros;
       unsigned  pauseMicros;
       unsigned  sleepMicros = 15000;
@@ -34,22 +36,29 @@ namespace cw
 
     inline thread_t* _handleToPtr(handle_t h) { return handleToPtr<handle_t,thread_t>(h); }
 
+    // Called from client thread to wait for the internal thread to transition to a specified state.
     rc_t _waitForState( thread_t* p, unsigned stateId )
     {
       unsigned waitTimeMicroSecs = 0;
-
-      while( p->stateId != stateId && waitTimeMicroSecs < p->stateMicros )
+      stateId_t curStateId;
+      
+      do
       {
-        sleepUs( p->sleepMicros );
-        waitTimeMicroSecs += p->sleepMicros;
-      }
+        curStateId = p->stateId.load(std::memory_order_acquire);
 
-      return p->stateId==stateId ? kOkRC :  kTimeOutRC;
+        if(curStateId == stateId )
+          break;
+        
+        sleepUs( p->sleepMicros );
+
+      }while( waitTimeMicroSecs < p->stateMicros );
+      
+      return curStateId==stateId ? kOkRC :  kTimeOutRC;
     }
 
     void _threadCleanUpCallback(void* p)
     {
-      ((thread_t*)p)->stateId = kExitedThId;
+      ((thread_t*)p)->stateId.store(kExitedThId,std::memory_order_release);
     }
   
 
@@ -61,36 +70,43 @@ namespace cw
       // thread terminates unexpectedly or pthread_cleanup_pop() is called.
       pthread_cleanup_push(_threadCleanUpCallback,p);
 
-      while( cwIsFlag(p->doFlags,kDoExitThFl) == false )
+      unsigned curDoFlags = 0;
+      
+      do
       {
+        // get the current thread state (running or paused)
+        stateId_t curStateId = p->stateId.load(std::memory_order_relaxed);
 
         // if we are in the pause state
-        if( p->stateId == kPausedThId )
+        if( curStateId == kPausedThId )
         {
         
           sleepUs( p->pauseMicros );
 
+          curDoFlags = p->doFlags.load(std::memory_order_acquire);
+
           // check if we have been requested to leave the pause state
-          if( cwIsFlag(p->doFlags,kDoRunThFl) )
+          if( cwIsFlag(curDoFlags,kDoRunThFl) )
           {
-            p->doFlags = cwClrFlag(p->doFlags,kDoRunThFl);
-            p->stateId   = kRunningThId;
+            p->stateId.store(kRunningThId,std::memory_order_release);
           }
         }
-        else
+        else // ... we are in running state
         {
           // call the user-defined function
           if( p->func(p->funcArg)==false )
             break;
 
+          curDoFlags = p->doFlags.load(std::memory_order_acquire);
+          
           // check if we have been requested to enter the pause state
-          if( cwIsFlag(p->doFlags,kDoPauseThFl) )
+          if( cwIsFlag(curDoFlags,kDoPauseThFl) )
           {
-            p->doFlags = cwClrFlag(p->doFlags,kDoPauseThFl);
-            p->stateId   = kPausedThId;        
+            p->stateId.store(kPausedThId,std::memory_order_release);
           }
         }
-      }
+        
+      }while( cwIsFlag(curDoFlags,kDoExitThFl) == false );
 
       pthread_cleanup_pop(1);
 	
@@ -157,7 +173,7 @@ cw::rc_t cw::thread::destroy( handle_t& hRef )
   thread_t* p  = _handleToPtr(hRef);
 
   // tell the thread to exit
-  p->doFlags = cwSetFlag(p->doFlags,kDoExitThFl);
+  p->doFlags.store(kDoExitThFl,std::memory_order_release);
 
   // wait for the thread to exit and then deallocate the thread object
   if((rc = _waitForState(p,kExitedThId)) != kOkRC )
@@ -184,7 +200,8 @@ cw::rc_t cw::thread::pause( handle_t h, unsigned cmdFlags )
   bool      pauseFl    = cwIsFlag(cmdFlags,kPauseFl);
   bool      waitFl     = cwIsFlag(cmdFlags,kWaitFl);
   thread_t* p          = _handleToPtr(h);
-  bool      isPausedFl = p->stateId == kPausedThId;
+  stateId_t curStateId = p->stateId.load(std::memory_order_acquire);
+  bool      isPausedFl = curStateId == kPausedThId;
   unsigned  waitId;
  
   if( isPausedFl == pauseFl )
@@ -192,12 +209,12 @@ cw::rc_t cw::thread::pause( handle_t h, unsigned cmdFlags )
 
   if( pauseFl )
   {
-    p->doFlags = cwSetFlag(p->doFlags,kDoPauseThFl);
+    p->doFlags.store(kDoPauseThFl,std::memory_order_release);
     waitId = kPausedThId;
   }
   else
   {
-    p->doFlags = cwSetFlag(p->doFlags,kDoRunThFl);
+    p->doFlags.store(kDoRunThFl,std::memory_order_release);
     waitId = kRunningThId;
   }
 
@@ -217,7 +234,7 @@ cw::rc_t cw::thread::unpause( handle_t h )
 cw::thread::stateId_t cw::thread::state( handle_t h )
 {
   thread_t* p = _handleToPtr(h);
-  return p->stateId;
+  return p->stateId.load(std::memory_order_acquire);
 }
 
 cw::thread::thread_id_t cw::thread::id()