changeset 458:f60360209e5c

* Fix race condition in FFTFileCache when reading from the same FFT model
  from multiple threads (e.g. when applying more than one plugin at once)

--- a/data/fft/FFTFileCache.cpp	Tue Oct 14 16:36:35 2008 +0000
+++ b/data/fft/FFTFileCache.cpp	Wed Oct 15 12:08:02 2008 +0000
@@ -72,16 +72,21 @@
     MutexLocker locker(&m_writeMutex, "FFTFileCache::resize::m_writeMutex");
 
     m_mfc->resize(width, height * 2 + m_factorSize);
-    if (m_readbuf) {
-        delete[] m_readbuf;
-        m_readbuf = 0;
+
+    {
+        MutexLocker locker(&m_readbufMutex, "FFTFileCache::resize::m_readMutex");
+        if (m_readbuf) {
+            delete[] m_readbuf;
+            m_readbuf = 0;
+        }
     }
+
     if (m_writebuf) {
         delete[] m_writebuf;
     }
     m_writebuf = new char[(height * 2 + m_factorSize) * m_mfc->getCellSize()];
 }
-
+    
 void
 FFTFileCache::reset()
 {
@@ -302,7 +307,7 @@
 }
 
 void
-FFTFileCache::populateReadBuf(size_t x) const
+FFTFileCache::populateReadBuf(size_t x) const // m_readbufMutex already held
 {
     Profiler profiler("FFTFileCache::populateReadBuf", false);
 

--- a/data/fft/FFTFileCache.h	Tue Oct 14 16:36:35 2008 +0000
+++ b/data/fft/FFTFileCache.h	Wed Oct 15 12:08:02 2008 +0000
@@ -62,31 +62,43 @@
     mutable size_t m_readbufWidth;
 
     float getFromReadBufStandard(size_t x, size_t y) const {
+        m_readbufMutex.lock();
         if (m_readbuf &&
             (m_readbufCol == x || (m_readbufWidth > 1 && m_readbufCol+1 == x))) {
-            return ((float *)m_readbuf)[(x - m_readbufCol) * m_mfc->getHeight() + y];
+            float v = ((float *)m_readbuf)[(x - m_readbufCol) * m_mfc->getHeight() + y];
+            m_readbufMutex.unlock();
+            return v;
         } else {
             populateReadBuf(x);
+            m_readbufMutex.unlock();
             return getFromReadBufStandard(x, y);
         }
     }
 
     float getFromReadBufCompactUnsigned(size_t x, size_t y) const {
+        m_readbufMutex.lock();
         if (m_readbuf &&
             (m_readbufCol == x || (m_readbufWidth > 1 && m_readbufCol+1 == x))) {
-            return ((uint16_t *)m_readbuf)[(x - m_readbufCol) * m_mfc->getHeight() + y];
+            float v = ((uint16_t *)m_readbuf)[(x - m_readbufCol) * m_mfc->getHeight() + y];
+            m_readbufMutex.unlock();
+            return v;
         } else {
             populateReadBuf(x);
+            m_readbufMutex.unlock();
             return getFromReadBufCompactUnsigned(x, y);
         }
     }
 
     float getFromReadBufCompactSigned(size_t x, size_t y) const {
+        m_readbufMutex.lock();
         if (m_readbuf &&
             (m_readbufCol == x || (m_readbufWidth > 1 && m_readbufCol+1 == x))) {
-            return ((int16_t *)m_readbuf)[(x - m_readbufCol) * m_mfc->getHeight() + y];
+            float v = ((int16_t *)m_readbuf)[(x - m_readbufCol) * m_mfc->getHeight() + y];
+            m_readbufMutex.unlock();
+            return v;
         } else {
             populateReadBuf(x);
+            m_readbufMutex.unlock();
             return getFromReadBufCompactSigned(x, y);
         }
     }
@@ -99,6 +111,7 @@
         if (m_storageType != Compact) {
             return getFromReadBufStandard(col, h - 1);
         } else {
+            m_readbufMutex.lock();
             union {
                 float f;
                 uint16_t u[2];
@@ -111,6 +124,7 @@
             size_t ix = (col - m_readbufCol) * m_mfc->getHeight() + h;
             factor.u[0] = ((uint16_t *)m_readbuf)[ix - 2];
             factor.u[1] = ((uint16_t *)m_readbuf)[ix - 1];
+            m_readbufMutex.unlock();
             return factor.f;
         }
     }
@@ -133,6 +147,7 @@
 
     MatrixFile *m_mfc;
     QMutex m_writeMutex;
+    mutable QMutex m_readbufMutex;
     StorageType m_storageType;
     size_t m_factorSize;
 };