comparison data/fft/FFTDataServer.h @ 335:02d2ad95ea52 spectrogram-cache-rejig

* Get storage advice for each cache in an FFT data server.  Allows us to be
  more confident about the actual memory situation and cut over from memory
  to disc part way through an FFT calculation if necessary.  StorageAdviser
  is now a bit too optimistic though (it's too keen to allocate large numbers
  of small blocks in memory).

     size_t m_width;
     size_t m_height;
     size_t m_cacheWidth;
     size_t m_cacheWidthPower;
     size_t m_cacheWidthMask;
-    bool m_memoryCache;
-    bool m_compactCache;
+
+    int m_lastUsedCache;
+    FFTCache *getCache(size_t x, size_t &col) {
+        col   = x & m_cacheWidthMask;
+        int c = x >> m_cacheWidthPower;
+        // The only use of m_lastUsedCache without a lock is to
+        // establish whether a cache has been created at all (they're
+        // created on demand, but not destroyed until the server is).
+        if (c == m_lastUsedCache) return m_caches[c];
+        else return getCacheAux(c);
+    }
+    bool haveCache(size_t x) {
+        int c = x >> m_cacheWidthPower;
+        if (c == m_lastUsedCache) return true;
+        else return (m_caches[c] != 0);
+    }
 
     typedef std::vector<FFTCache *> CacheVector;
     CacheVector m_caches;
     
     typedef std::deque<int> IntQueue;
     IntQueue m_dormantCaches;
 
-    int m_lastUsedCache;
-    FFTCache *getCache(size_t x, size_t &col) {
-        col   = x % m_cacheWidth;
-        int c = x / m_cacheWidth;
-        // The only use of m_lastUsedCache without a lock is to
-        // establish whether a cache has been created at all (they're
-        // created on demand, but not destroyed until the server is).
-        if (c == m_lastUsedCache) return m_caches[c];
-        else return getCacheAux(c);
-    }
-    bool haveCache(size_t x) {
-        int c = x / m_cacheWidth;
-        if (c == m_lastUsedCache) return true;
-        else return (m_caches[c] != 0);
-    }
+    StorageAdviser::Criteria m_criteria;
+
+    void getStorageAdvice(size_t w, size_t h, bool &memory, bool &compact);
         
     FFTCache *getCacheAux(size_t c);
     QMutex m_writeMutex;
     QWaitCondition m_condition;