Merge pull request #11 from julsal/master

casting bugs and minor optimization

src/main/java/com/spotify/annoy/ANNIndex.java

@@ -23,10 +23,11 @@ public class ANNIndex implements AnnoyIndex {
 
   // size of C structs in bytes (initialized in init)
   private final int K_NODE_HEADER_STYLE;
-  private final int NODE_SIZE;
+  private final long NODE_SIZE;
 
   private final int INT_SIZE = 4;
   private final int FLOAT_SIZE = 4;
+  private final int MAX_NODES_IN_BUFFER;
   private final int BLOCK_SIZE;
   private RandomAccessFile memoryMappedFile;
 
@@ -69,9 +70,9 @@ public ANNIndex(final int dimension,
     // them where the separating plane normally goes)
     this.MIN_LEAF_SIZE = DIMENSION + 2;
     this.NODE_SIZE = K_NODE_HEADER_STYLE + FLOAT_SIZE * DIMENSION;
-    this.BLOCK_SIZE = blockSize == 0 ?
-            Integer.MAX_VALUE / NODE_SIZE : blockSize * NODE_SIZE;
-
+    this.MAX_NODES_IN_BUFFER = (int) (blockSize == 0 ?
+            Integer.MAX_VALUE / NODE_SIZE : blockSize * NODE_SIZE);
+    BLOCK_SIZE = (int) (this.MAX_NODES_IN_BUFFER * NODE_SIZE);
     roots = new ArrayList<>();
     load(filename);
   }
@@ -83,7 +84,8 @@ private void load(final String filename) throws IOException {
       throw new IOException("Index is a 0-byte file?");
     }
 
-    int buffIndex =  (int) ((fileSize - 1) / BLOCK_SIZE);
+    int numNodes = (int) (fileSize / NODE_SIZE);
+    int buffIndex =  (numNodes - 1) / MAX_NODES_IN_BUFFER;
     int rest = (int) (fileSize % BLOCK_SIZE);
     int blockSize = (rest > 0 ? rest : BLOCK_SIZE);
     long position = fileSize - blockSize;
@@ -99,7 +101,7 @@ private void load(final String filename) throws IOException {
 
       buffers[buffIndex--] = annBuf;
 
-      for (int i = blockSize - NODE_SIZE; process && i >= 0; i -= NODE_SIZE) {
+      for (int i = blockSize - (int) NODE_SIZE; process && i >= 0; i -= NODE_SIZE) {
         index -= NODE_SIZE;
         int k = annBuf.getInt(i);  // node[i].n_descendants
         if (m == -1 || k == m) {
@@ -115,21 +117,21 @@ private void load(final String filename) throws IOException {
   }
 
   private float getFloatInAnnBuf(long pos) {
-    int b = (int) pos / BLOCK_SIZE;
-    int f = (int) pos % BLOCK_SIZE;
+    int b = (int) (pos / BLOCK_SIZE);
+    int f = (int) (pos % BLOCK_SIZE);
     return buffers[b].getFloat(f);
   }
 
   private int getIntInAnnBuf(long pos) {
-    int b = (int) pos / BLOCK_SIZE;
-    int i = (int) pos % BLOCK_SIZE;
+    int b = (int) (pos / BLOCK_SIZE);
+    int i = (int) (pos % BLOCK_SIZE);
     return buffers[b].getInt(i);
   }
 
   @Override
   public void getNodeVector(final long nodeOffset, float[] v) {
-    MappedByteBuffer nodeBuf = buffers[(int) nodeOffset / BLOCK_SIZE];
-    int offset = (int) (nodeOffset % BLOCK_SIZE) + K_NODE_HEADER_STYLE;
+    MappedByteBuffer nodeBuf = buffers[(int) (nodeOffset / BLOCK_SIZE)];
+    int offset = (int) ((nodeOffset % BLOCK_SIZE) + K_NODE_HEADER_STYLE);
     for (int i = 0; i < DIMENSION; i++) {
       v[i] = nodeBuf.getFloat(offset + i * FLOAT_SIZE);
     }