zynaddsubfx

commit 13b0f975482722ac8802755349359bf2f64b6610
parent bf04e520c6142471ffe4e8f740ec007a007a245f
Author: fundamental <mark.d.mccurry@gmail.com>
Date:   Tue, 11 May 2010 08:46:00 -0400

Nio: Thread Safety

Converting SafeQueue to use semaphores

Diffstat:
M
src/Nio/SafeQueue.cpp
 | 
43
+++++++++++++++++++++----------------------
M
src/Nio/SafeQueue.h
 | 
12
+++++++++---
M
src/Nio/WavEngine.cpp
 | 
20
++++++++++++--------

3 files changed, 42 insertions(+), 33 deletions(-)
diff --git a/src/Nio/SafeQueue.cpp b/src/Nio/SafeQueue.cpp
@@ -3,12 +3,16 @@ template<class T>
 SafeQueue<T>::SafeQueue(size_t maxlen)
     :writePtr(0),readPtr(0),bufSize(maxlen)
 {
+    sem_init(&w_space, PTHREAD_PROCESS_PRIVATE, maxlen-1);
+    sem_init(&r_space, PTHREAD_PROCESS_PRIVATE, 0);
     buffer = new T[maxlen];
 }
 
 template<class T>
 SafeQueue<T>::~SafeQueue()
 {
+    sem_destroy(&w_space);
+    sem_destroy(&r_space);
     delete[] buffer;
 }
 
@@ -21,33 +25,17 @@ unsigned int SafeQueue<T>::size() const
 template<class T>
 unsigned int SafeQueue<T>::rSpace() const
 {
-  size_t w, r;
-
-  w = writePtr;
-  r = readPtr;
-
-  if (w > r) {
-    return w - r;
-  }
-  else {
-    return (w - r + bufSize) % bufSize;
-  }
+    int space = 0;
+    sem_getvalue(&r_space, &space);
+    return space;
 }
 
 template<class T>
 unsigned int SafeQueue<T>::wSpace() const
 {
-  size_t w, r;
-
-  w = writePtr;
-  r = readPtr - 1;
-
-  if (r > w) {
-    return r - w;
-  }
-  else {
-    return (r - w + bufSize) % bufSize;
-  }
+    int space = 0;
+    sem_getvalue(&w_space, &space);
+    return space;
 }
 
 template<class T>
@@ -60,6 +48,10 @@ int SafeQueue<T>::push(const T &in)
     size_t w = (writePtr + 1) % bufSize;
     buffer[w] = in;
     writePtr = w;
+
+    //adjust ranges
+    sem_wait(&w_space);//guaranteed not to wait
+    sem_post(&r_space);
     return 0;
 }
 
@@ -73,11 +65,18 @@ int SafeQueue<T>::pop(T &out)
     size_t r = (readPtr + 1) % bufSize;
     out = buffer[r];
     readPtr = r;
+
+    //adjust ranges
+    sem_wait(&r_space);//guaranteed not to wait
+    sem_post(&w_space);
     return 0;
 }
 
 template<class T>
 void SafeQueue<T>::clear()
 {
+    //thread unsafe
+    while(!sem_trywait(&r_space))
+        sem_post(&w_space);
     readPtr = writePtr;
 }
diff --git a/src/Nio/SafeQueue.h b/src/Nio/SafeQueue.h
@@ -2,6 +2,7 @@
 #ifndef SAFEQUEUE_H
 #define SAFEQUEUE_H
 #include <cstdlib>
+#include <semaphore.h>
 
 /**
  * C++ thread safe lockless queue
@@ -28,10 +29,15 @@ class SafeQueue
         unsigned int wSpace() const;
         unsigned int rSpace() const;
 
-        //next writting spot
-        volatile size_t writePtr;
+        //write space
+        mutable sem_t w_space;
+        //read space
+        mutable sem_t r_space;
+
+        //next writing spot
+        size_t writePtr;
         //next reading spot
-        volatile size_t readPtr;
+        size_t readPtr;
         const size_t bufSize;
         T *buffer;
 };
diff --git a/src/Nio/WavEngine.cpp b/src/Nio/WavEngine.cpp
@@ -80,8 +80,8 @@ void WavEngine::push(Stereo<REALTYPE *> smps, size_t len)
     for(size_t i = 0; i < len; ++i) {
         buffer.push(*smps.l()++);
         buffer.push(*smps.r()++);
-        sem_post(&work);
     }
+    sem_post(&work);
 }
 
 void WavEngine::newFile(WavFile *_file)
@@ -104,17 +104,21 @@ void *WavEngine::_AudioThread(void *arg)
 
 void *WavEngine::AudioThread()
 {
-    short int recordbuf_16bit[2];
+    short *recordbuf_16bit = new short[2*SOUND_BUFFER_SIZE];
 
     while(!sem_wait(&work) && pThread)
     {
-        float left=0.0f, right=0.0f;
-        buffer.pop(left);
-        buffer.pop(right);
-        recordbuf_16bit[0] = limit((int)(left  * 32767.0), -32768, 32767);
-        recordbuf_16bit[1] = limit((int)(right * 32767.0), -32768, 32767);
-        file->writeStereoSamples(1, recordbuf_16bit);
+        for(int i = 0; i < SOUND_BUFFER_SIZE; ++i) {
+            float left=0.0f, right=0.0f;
+            buffer.pop(left);
+            buffer.pop(right);
+            recordbuf_16bit[2*i]   = limit((int)(left  * 32767.0), -32768, 32767);
+            recordbuf_16bit[2*i+1] = limit((int)(right * 32767.0), -32768, 32767);
+            file->writeStereoSamples(SOUND_BUFFER_SIZE, recordbuf_16bit);
+        }
     }
+
+    delete[] recordbuf_16bit;
     pthread_exit(NULL);
 }