package water;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Map;
import java.util.TreeMap;
/**
* Convenience class for easy access to user-visible keys in the cloud with enabled caching.
*
* This class represents snapshot of user keys currently stored in the cloud and contains methods to retrieve it.
* It contains all user keys stored in the cloud at one particular point in time (marked by timestamp member variable).
* Snapshot does not contain the actual values and no values are fetched from remote by requesting new snapshot.
*
* KeySnapshot itself is a set of user keys with some additional info (e.g. type and size) and some convenience functions
* supporting filtering and instantiating of classes pointed to by the keys
*
* @author tomas
*/
public class KeySnapshot {
/** Class to filter keys from the snapshot. */
public abstract static class KVFilter {
/** @param k KeyInfo to be filtered
* @return true if the key should be included in the new (filtered) set. */
public abstract boolean filter(KeyInfo k);
}
/** Class containing information about user keys.
* Contains the actual key and all interesting information except the data itself. */
public static final class KeyInfo extends Iced implements Comparable<KeyInfo>{
public final Key _key;
public final int _type;
public final int _sz;
public final byte _backEnd;
public KeyInfo(Key k, Value v){
_key = k;
_type = v.type();
_sz = v._max;
_backEnd = v.backend();
}
@Override public int compareTo(KeyInfo ki) { return _key.compareTo(ki._key);}
public boolean isFrame() { return _type == TypeMap.FRAME; }
public boolean isLockable(){ return TypeMap.theFreezable(_type) instanceof Lockable; }
}
private static final long _updateInterval = 1000;
private static volatile KeySnapshot _cache;
public final KeyInfo [] _keyInfos;
/** (local) Time of creation. */
public final long timestamp;
/** @return cached version of KeySnapshot */
public static KeySnapshot cache(){return _cache;}
/** Filter the snapshot providing custom filter.
* Only the keys for which filter returns true will be present in the new snapshot.
* @param kvf The filter
* @return filtered snapshot
*/
public KeySnapshot filter(KVFilter kvf){
ArrayList<KeyInfo> res = new ArrayList<>();
for(KeyInfo kinfo: _keyInfos)
if(kvf.filter(kinfo))res.add(kinfo);
return new KeySnapshot(res.toArray(new KeyInfo[res.size()]));
}
KeySnapshot(KeyInfo[] snapshot){
_keyInfos = snapshot;
timestamp = System.currentTimeMillis();
}
/**
@return array of all keys in this snapshot.
*/
public Key[] keys(){
Key [] res = new Key[_keyInfos.length];
for(int i = 0; i < _keyInfos.length; ++i)
res[i] = _keyInfos[i]._key;
return res;
}
/** Return all the keys of the given class.
* @param clz Class
* @return array of keys in this snapshot with the given class */
public static Key[] globalKeysOfClass(final Class clz) {
return KeySnapshot.globalSnapshot().filter(new KeySnapshot.KVFilter() {
@Override public boolean filter(KeySnapshot.KeyInfo k) { return Value.isSubclassOf(k._type, clz); }
}).keys();
}
/** @param c Class objects of which should be instantiated
* @param <T> Generic class being fetched
* @return all objects (of the proper class) pointed to by this key snapshot (and still present in the K/V at the time of invocation). */
public <T extends Iced> Map<String, T> fetchAll(Class<T> c) { return fetchAll(c,false,0,Integer.MAX_VALUE);}
/** @param c Class objects of which should be instantiated
* @param <T> Generic class being fetched
* @param exact - subclasses will not be included if set.
* @return all objects (of the proper class) pointed to by this key snapshot (and still present in the K/V at the time of invocation). */
public <T extends Iced> Map<String, T> fetchAll(Class<T> c, boolean exact) { return fetchAll(c,exact,0,Integer.MAX_VALUE);}
/** @param c Class objects of which should be instantiated
* @param <T> Generic class being fetched
* @param exact - subclasses will not be included if set.
* @param offset - skip first offset values matching the given type
* @param limit - produce only up to the limit objects.
* @return all objects (of the proper class) pointed to by this key snapshot (and still present in the K/V at the time of invocation). */
public <T extends Iced> Map<String, T> fetchAll(Class<T> c, boolean exact, int offset, int limit) {
TreeMap<String, T> res = new TreeMap<>();
final int typeId = TypeMap.onIce(c.getName());
for (KeyInfo kinfo : _keyInfos) {
if (kinfo._type == typeId || (!exact && Value.isSubclassOf(kinfo._type, c))) {
if (offset > 0) {
--offset;
continue;
}
Value v = DKV.get(kinfo._key);
if (v != null) {
T t = v.get();
res.put(kinfo._key.toString(), t);
if (res.size() == limit)
break;
}
}
}
return res;
}
/**
* Get the user keys from this node only.
* Includes non-local keys which are cached locally.
* @return KeySnapshot containing keys from the local K/V.
*/
public static KeySnapshot localSnapshot(){return localSnapshot(false);}
/**
* Get the user keys from this node only.
* @param homeOnly - exclude the non-local (cached) keys if set
* @return KeySnapshot containing keys from the local K/V.
*/
public static KeySnapshot localSnapshot(boolean homeOnly){
Object [] kvs = H2O.STORE.raw_array();
ArrayList<KeyInfo> res = new ArrayList<>();
for(int i = 2; i < kvs.length; i+= 2){
Object ok = kvs[i];
if( !(ok instanceof Key ) ) continue; // Ignore tombstones and Primes and null's
Key key = (Key )ok;
if(!key.user_allowed())continue;
if(homeOnly && !key.home())continue;
// Raw array can contain regular and also wrapped values into Prime marker class:
// - if we see Value object, create instance of KeyInfo
// - if we do not see Value object directly (it can be wrapped in Prime marker class),
// try to unwrap it via calling STORE.get (~H2O.get) and then
// look at wrapped value again.
Value val = Value.STORE_get(key);
if( val == null ) continue;
res.add(new KeyInfo(key,val));
}
final KeyInfo [] arr = res.toArray(new KeyInfo[res.size()]);
Arrays.sort(arr);
return new KeySnapshot(arr);
}
/**
* @return KeySnapshot containing user keys from all the nodes.
*/
public static KeySnapshot globalSnapshot(){ return globalSnapshot(-1);}
/**
* Cache-enabled call to get global key snapshot.
* User can provide time tolerance to indicate a how old the snapshot can be.
* @param timeTolerance - tolerated age of the cache in millis.
* If the last snapshot is bellow this value, cached version will be returned immediately.
* Otherwise new snapshot must be obtained by from all nodes.
* @return KeySnapshot containing user keys from all the nodes.
*/
public static KeySnapshot globalSnapshot(long timeTolerance){
KeySnapshot res = _cache;
final long t = System.currentTimeMillis();
if(res == null || (t - res.timestamp) > timeTolerance)
res = new KeySnapshot((new GlobalUKeySetTask().doAllNodes()._res));
else if(t - res.timestamp > _updateInterval)
H2O.submitTask(new H2O.H2OCountedCompleter() {
@Override
public void compute2() {
new GlobalUKeySetTask().doAllNodes();
}
});
return res;
}
// task to grab all user keys (+ info) form all around the cloud
// updates the cache when done
private static class GlobalUKeySetTask extends MRTask<GlobalUKeySetTask> {
KeyInfo [] _res;
GlobalUKeySetTask() { super(H2O.MIN_HI_PRIORITY); }
@Override public void setupLocal(){ _res = localSnapshot(true)._keyInfos;}
@Override public void reduce(GlobalUKeySetTask gbt){
if(_res == null)_res = gbt._res;
else if(gbt._res != null){ // merge sort keys together
KeyInfo [] res = new KeyInfo[_res.length + gbt._res.length];
int j = 0, k = 0;
for(int i = 0; i < res.length; ++i)
res[i] = j < gbt._res.length && (k == _res.length || gbt._res[j].compareTo(_res[k]) < 0)?gbt._res[j++]:_res[k++];
_res = res;
}
}
@Override public void postGlobal(){
_cache = new KeySnapshot(_res);
}
}
}