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CachedBatchReadsMap.java
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CachedBatchReadsMap.java
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package storm.trident.state.map;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import storm.trident.state.ValueUpdater;
public class CachedBatchReadsMap<T> {
public static class RetVal<T> {
public boolean cached;
public T val;
public RetVal(T v, boolean c) {
val = v;
cached = c;
}
}
Map<List<Object>, T> _cached = new HashMap<List<Object>, T>();
public IBackingMap<T> _delegate;
public CachedBatchReadsMap(IBackingMap<T> delegate) {
_delegate = delegate;
}
public void reset() {
_cached.clear();
}
public List<RetVal<T>> multiGet(List<List<Object>> keys) {
// TODO: can optimize further by only querying backing map for keys not in the cache
List<T> vals = _delegate.multiGet(keys);
List<RetVal<T>> ret = new ArrayList(vals.size());
for(int i=0; i<keys.size(); i++) {
List<Object> key = keys.get(i);
if(_cached.containsKey(key)) {
ret.add(new RetVal(_cached.get(key), true));
} else {
ret.add(new RetVal(vals.get(i), false));
}
}
return ret;
}
public void multiPut(List<List<Object>> keys, List<T> vals) {
_delegate.multiPut(keys, vals);
cache(keys, vals);
}
private void cache(List<List<Object>> keys, List<T> vals) {
for(int i=0; i<keys.size(); i++) {
List<Object> key = keys.get(i);
T val = vals.get(i);
_cached.put(key, val);
}
}
}