123 lines
3.6 KiB
Java
123 lines
3.6 KiB
Java
/*
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* MicroRange.java
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*
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* This source file is part of the FoundationDB open source project
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*
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* Copyright 2013-2018 Apple Inc. and the FoundationDB project authors
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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import java.util.ArrayList;
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import com.foundationdb.*;
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import com.foundationdb.async.Function;
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import com.foundationdb.subspace.Subspace;
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import com.foundationdb.tuple.Tuple;
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public class MicroRange {
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private static final FDB fdb;
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private static final Database db;
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private static final Subspace range;
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private static final int LIMIT = 10;
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static {
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fdb = FDB.selectAPIVersion(300);
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db = fdb.open();
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range = new Subspace(Tuple.from("R"));
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}
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private static boolean haltingCondition(byte[] key, byte[] value){
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return true;
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}
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public static void stopRangeSoon(TransactionContext tcx, final Range r){
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tcx.run(new Function<Transaction,Void>() {
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public Void apply(Transaction tr){
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// TODO This loop in recipe book.
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for(KeyValue kv : tr.getRange(r, ReadTransaction.ROW_LIMIT_UNLIMITED,
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false, StreamingMode.SMALL)){
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if(haltingCondition(kv.getKey(), kv.getValue())){
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break;
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}
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System.out.println(Tuple.fromBytes(kv.getKey()).toString()
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+ " " + Tuple.fromBytes(kv.getValue()).toString());
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}
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return null;
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}
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});
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}
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// TODO This method in recipe book.
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public static void getRangeLimited(TransactionContext tcx, final KeySelector begin, final KeySelector end){
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tcx.run(new Function<Transaction,Void>() {
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public Void apply(Transaction tr){
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boolean keysToCheck = true;
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ArrayList<Tuple> keysFound = new ArrayList<Tuple>();
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KeySelector n_begin = new KeySelector(begin.getKey(),true,begin.getOffset());
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while(keysToCheck){
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keysToCheck = false;
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for(KeyValue kv : tr.getRange(n_begin, end, LIMIT)){
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keysToCheck = true;
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Tuple t = Tuple.fromBytes(kv.getKey());
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if(keysFound.size() == 0
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|| !t.equals(keysFound.get(keysFound.size()-1))){
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keysFound.add(t);
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}
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}
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if(keysToCheck){
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n_begin = KeySelector.firstGreaterThan(keysFound.get(keysFound.size()-1).pack());
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ArrayList<Object> readableFound = new ArrayList<Object>();
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for(Tuple t : keysFound){
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readableFound.add(t.get(1));
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}
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System.out.println(readableFound);
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keysFound = new ArrayList<Tuple>();
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}
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}
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return null;
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}
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});
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}
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public static void clearSubspace(TransactionContext tcx, final Subspace s){
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tcx.run(new Function<Transaction,Void>() {
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public Void apply(Transaction tr){
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tr.clear(s.range());
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return null;
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}
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});
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}
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public static void populate(TransactionContext tcx, final Subspace s){
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tcx.run(new Function<Transaction,Void>() {
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public Void apply(Transaction tr){
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for(int i = 0; i < 10*LIMIT + LIMIT/2; i++){
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tr.set(s.pack(Tuple.from(i)), Tuple.from().pack());
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}
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return null;
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}
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});
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}
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public static void main(String[] args) {
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clearSubspace(db, range);
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populate(db, range);
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Range r = range.range();
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getRangeLimited(db, new KeySelector(r.begin,true,1), new KeySelector(r.end,true,1));
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}
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}
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