Java tutorial
/** * Licensed to the Apache Software Foundation (ASF) under one * or more contributor license agreements. See the NOTICE file * distributed with this work for additional information * regarding copyright ownership. The ASF licenses this file * to you under the Apache License, Version 2.0 (the * "License"); you may not use this file except in compliance * with the License. You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package com.twitter.distributedlog.acl; import com.google.common.base.Objects; import com.twitter.distributedlog.ZooKeeperClient; import com.twitter.distributedlog.thrift.AccessControlEntry; import com.twitter.util.Future; import com.twitter.util.Promise; import org.apache.thrift.TException; import org.apache.thrift.protocol.TJSONProtocol; import org.apache.thrift.transport.TMemoryBuffer; import org.apache.thrift.transport.TMemoryInputTransport; import org.apache.zookeeper.AsyncCallback; import org.apache.zookeeper.CreateMode; import org.apache.zookeeper.KeeperException; import org.apache.zookeeper.Watcher; import org.apache.zookeeper.data.Stat; import java.io.IOException; import java.io.UnsupportedEncodingException; import static com.google.common.base.Charsets.UTF_8; public class ZKAccessControl { private static final int BUFFER_SIZE = 4096; public static final AccessControlEntry DEFAULT_ACCESS_CONTROL_ENTRY = new AccessControlEntry(); public static class CorruptedAccessControlException extends IOException { private static final long serialVersionUID = 5391285182476211603L; public CorruptedAccessControlException(String zkPath, Throwable t) { super("Access Control @ " + zkPath + " is corrupted.", t); } } protected final AccessControlEntry accessControlEntry; protected final String zkPath; private int zkVersion; public ZKAccessControl(AccessControlEntry ace, String zkPath) { this(ace, zkPath, -1); } private ZKAccessControl(AccessControlEntry ace, String zkPath, int zkVersion) { this.accessControlEntry = ace; this.zkPath = zkPath; this.zkVersion = zkVersion; } @Override public int hashCode() { return Objects.hashCode(zkPath, accessControlEntry); } @Override public boolean equals(Object obj) { if (!(obj instanceof ZKAccessControl)) { return false; } ZKAccessControl other = (ZKAccessControl) obj; return Objects.equal(zkPath, other.zkPath) && Objects.equal(accessControlEntry, other.accessControlEntry); } @Override public String toString() { StringBuilder sb = new StringBuilder(); sb.append("entry(path=").append(zkPath).append(", acl=").append(accessControlEntry).append(")"); return sb.toString(); } public String getZKPath() { return zkPath; } public AccessControlEntry getAccessControlEntry() { return accessControlEntry; } public Future<ZKAccessControl> create(ZooKeeperClient zkc) { final Promise<ZKAccessControl> promise = new Promise<ZKAccessControl>(); try { zkc.get().create(zkPath, serialize(accessControlEntry), zkc.getDefaultACL(), CreateMode.PERSISTENT, new AsyncCallback.StringCallback() { @Override public void processResult(int rc, String path, Object ctx, String name) { if (KeeperException.Code.OK.intValue() == rc) { ZKAccessControl.this.zkVersion = 0; promise.setValue(ZKAccessControl.this); } else { promise.setException(KeeperException.create(KeeperException.Code.get(rc))); } } }, null); } catch (ZooKeeperClient.ZooKeeperConnectionException e) { promise.setException(e); } catch (InterruptedException e) { promise.setException(e); } catch (IOException e) { promise.setException(e); } return promise; } public Future<ZKAccessControl> update(ZooKeeperClient zkc) { final Promise<ZKAccessControl> promise = new Promise<ZKAccessControl>(); try { zkc.get().setData(zkPath, serialize(accessControlEntry), zkVersion, new AsyncCallback.StatCallback() { @Override public void processResult(int rc, String path, Object ctx, Stat stat) { if (KeeperException.Code.OK.intValue() == rc) { ZKAccessControl.this.zkVersion = stat.getVersion(); promise.setValue(ZKAccessControl.this); } else { promise.setException(KeeperException.create(KeeperException.Code.get(rc))); } } }, null); } catch (ZooKeeperClient.ZooKeeperConnectionException e) { promise.setException(e); } catch (InterruptedException e) { promise.setException(e); } catch (IOException e) { promise.setException(e); } return promise; } public static Future<ZKAccessControl> read(final ZooKeeperClient zkc, final String zkPath, Watcher watcher) { final Promise<ZKAccessControl> promise = new Promise<ZKAccessControl>(); try { zkc.get().getData(zkPath, watcher, new AsyncCallback.DataCallback() { @Override public void processResult(int rc, String path, Object ctx, byte[] data, Stat stat) { if (KeeperException.Code.OK.intValue() == rc) { try { AccessControlEntry ace = deserialize(zkPath, data); promise.setValue(new ZKAccessControl(ace, zkPath, stat.getVersion())); } catch (IOException ioe) { promise.setException(ioe); } } else { promise.setException(KeeperException.create(KeeperException.Code.get(rc))); } } }, null); } catch (ZooKeeperClient.ZooKeeperConnectionException e) { promise.setException(e); } catch (InterruptedException e) { promise.setException(e); } return promise; } public static Future<Void> delete(final ZooKeeperClient zkc, final String zkPath) { final Promise<Void> promise = new Promise<Void>(); try { zkc.get().delete(zkPath, -1, new AsyncCallback.VoidCallback() { @Override public void processResult(int rc, String path, Object ctx) { if (KeeperException.Code.OK.intValue() == rc || KeeperException.Code.NONODE.intValue() == rc) { promise.setValue(null); } else { promise.setException(KeeperException.create(KeeperException.Code.get(rc))); } } }, null); } catch (ZooKeeperClient.ZooKeeperConnectionException e) { promise.setException(e); } catch (InterruptedException e) { promise.setException(e); } return promise; } static byte[] serialize(AccessControlEntry ace) throws IOException { TMemoryBuffer transport = new TMemoryBuffer(BUFFER_SIZE); TJSONProtocol protocol = new TJSONProtocol(transport); try { ace.write(protocol); transport.flush(); return transport.toString(UTF_8.name()).getBytes(UTF_8); } catch (TException e) { throw new IOException("Failed to serialize access control entry : ", e); } catch (UnsupportedEncodingException uee) { throw new IOException("Failed to serialize acesss control entry : ", uee); } } static AccessControlEntry deserialize(String zkPath, byte[] data) throws IOException { if (data.length == 0) { return DEFAULT_ACCESS_CONTROL_ENTRY; } AccessControlEntry ace = new AccessControlEntry(); TMemoryInputTransport transport = new TMemoryInputTransport(data); TJSONProtocol protocol = new TJSONProtocol(transport); try { ace.read(protocol); } catch (TException e) { throw new CorruptedAccessControlException(zkPath, e); } return ace; } }