@Override
public synchronized void close() throws IOException {
super.close();
DataOutputStream out = fs.create(new Path(dir, BLOOM_FILE_NAME), true);
bloomFilter.write(out);
out.flush();
out.close();
}
@Override
public synchronized void append(WritableComparable key, Writable val) throws IOException {
super.append(key, val);
buf.reset();
key.write(buf);
bloomKey.set(byteArrayForBloomKey(buf), 1.0);
bloomFilter.add(bloomKey);
}
/**
* Checks if this MapFile has the indicated key. The membership test is performed using a Bloom
* filter, so the result has always non-zero probability of false positives.
*
* @param key key to check
* @return false iff key doesn't exist, true if key probably exists.
* @throws IOException
*/
public boolean probablyHasKey(WritableComparable key) throws IOException {
if (bloomFilter == null) {
return true;
}
buf.reset();
key.write(buf);
bloomKey.set(byteArrayForBloomKey(buf), 1.0);
return bloomFilter.membershipTest(bloomKey);
}
private void initBloomFilter(Path dirName, Configuration conf) {
try {
FileSystem fs = dirName.getFileSystem(conf);
DataInputStream in = fs.open(new Path(dirName, BLOOM_FILE_NAME));
bloomFilter = new DynamicBloomFilter();
bloomFilter.readFields(in);
in.close();
} catch (IOException ioe) {
LOG.warn("Can't open BloomFilter: " + ioe + " - fallback to MapFile.");
bloomFilter = null;
}
}
