92 lines
2.6 KiB
Java
92 lines
2.6 KiB
Java
/*
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* MicroBlob.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 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 MicroBlob {
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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 blob;
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private static final int CHUNK_SIZE = 5;
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static{
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fdb = FDB.selectAPIVersion(300);
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db = fdb.open();
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blob = new Subspace(Tuple.from("B"));
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}
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// Clears subspace.
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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(Range.startsWith(s.getKey()));
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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 is in the recipe book.
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// Writes to the blobs.
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public static void writeBlob(TransactionContext tcx, final String data){
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if(data.length() == 0) return;
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tcx.run(new Function<Transaction,Void>() {
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public Void apply(Transaction tr) {
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int numChunks = (data.length() + CHUNK_SIZE - 1)/CHUNK_SIZE;
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int chunkSize = (data.length() + numChunks)/numChunks;
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for(int i = 0; i*chunkSize < data.length(); i++){
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int start = i*chunkSize;
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int end = ((i+1)*chunkSize <= data.length()) ? ((i+1)*chunkSize) : (data.length());
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tr.set(blob.subspace(Tuple.from(start)).pack(),
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Tuple.from(data.substring(start, end)).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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// TODO This method is in the recipe book.
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// Reads from the blobs.
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public static String readBlob(TransactionContext tcx){
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return tcx.run(new Function<Transaction,String>() {
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public String apply(Transaction tr){
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StringBuilder value = new StringBuilder();
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for(KeyValue kv : tr.getRange(blob.range())){
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value.append(Tuple.fromBytes(kv.getValue()).getString(0));
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}
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return value.toString();
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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, blob);
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writeBlob(db, "ABCDEFGHIJKLMNOPQRSTUVWXYZ");
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System.out.println(readBlob(db));
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}
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}
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