| // Copyright (C) 2013 The Android Open Source Project |
| // |
| // Licensed 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.google.gerrit.client.rpc; |
| |
| import com.google.gwt.user.client.rpc.AsyncCallback; |
| |
| import java.util.ArrayList; |
| import java.util.HashMap; |
| import java.util.List; |
| import java.util.Map; |
| |
| /** |
| * Class for grouping together callbacks and calling them in order. |
| * <p> |
| * Callbacks are added to the group with {@link #add(AsyncCallback)}, which |
| * returns a wrapped callback suitable for passing to an asynchronous RPC call. |
| * The enclosing group buffers returned results and ensures that |
| * {@code onSuccess} is called exactly once for each callback in the group, in |
| * the same order that callbacks were added. This allows callers to, for |
| * example, use a {@link ScreenLoadCallback} as the last callback in the list |
| * and only display the screen once all callbacks have succeeded. |
| * <p> |
| * In the event of a failure, the <em>first</em> caught exception is sent to |
| * <em>all</em> callbacks' {@code onFailure} methods, in order; subsequent |
| * successes or failures are all ignored. Note that this means |
| * {@code onFailure} may be called with an exception unrelated to the callback |
| * processing it. |
| */ |
| public class CallbackGroup { |
| private final List<Object> callbacks; |
| private final Map<Object, Object> results; |
| private boolean failed; |
| |
| public CallbackGroup() { |
| callbacks = new ArrayList<Object>(); |
| results = new HashMap<Object, Object>(); |
| } |
| |
| public <T> AsyncCallback<T> add(final AsyncCallback<T> cb) { |
| callbacks.add(cb); |
| return new AsyncCallback<T>() { |
| @Override |
| public void onSuccess(T result) { |
| results.put(cb, result); |
| CallbackGroup.this.onSuccess(); |
| } |
| |
| @Override |
| public void onFailure(Throwable caught) { |
| CallbackGroup.this.onFailure(caught); |
| } |
| }; |
| } |
| |
| public <T> com.google.gwtjsonrpc.common.AsyncCallback<T> addGwtjsonrpc( |
| final com.google.gwtjsonrpc.common.AsyncCallback<T> cb) { |
| callbacks.add(cb); |
| return new com.google.gwtjsonrpc.common.AsyncCallback<T>() { |
| @Override |
| public void onSuccess(T result) { |
| results.put(cb, result); |
| CallbackGroup.this.onSuccess(); |
| } |
| |
| @Override |
| public void onFailure(Throwable caught) { |
| CallbackGroup.this.onFailure(caught); |
| } |
| }; |
| } |
| |
| private void onSuccess() { |
| if (results.size() < callbacks.size()) { |
| return; |
| } |
| for (Object o : callbacks) { |
| Object result = results.get(o); |
| if (o instanceof AsyncCallback) { |
| @SuppressWarnings("unchecked") |
| AsyncCallback<Object> cb = (AsyncCallback<Object>) o; |
| cb.onSuccess(result); |
| } else { |
| @SuppressWarnings("unchecked") |
| com.google.gwtjsonrpc.common.AsyncCallback<Object> cb = |
| (com.google.gwtjsonrpc.common.AsyncCallback<Object>) o; |
| cb.onSuccess(result); |
| } |
| } |
| } |
| |
| private void onFailure(Throwable caught) { |
| if (failed) { |
| return; |
| } |
| failed = true; |
| for (Object o : callbacks) { |
| if (o instanceof AsyncCallback) { |
| @SuppressWarnings("unchecked") |
| AsyncCallback<Object> cb = (AsyncCallback<Object>) o; |
| cb.onFailure(caught); |
| } else { |
| @SuppressWarnings("unchecked") |
| com.google.gwtjsonrpc.common.AsyncCallback<Object> cb = |
| (com.google.gwtjsonrpc.common.AsyncCallback<Object>) o; |
| cb.onFailure(caught); |
| } |
| } |
| } |
| } |