| // Copyright (C) 2009 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.httpd.rpc; |
| |
| import com.google.gerrit.common.errors.CorruptEntityException; |
| import com.google.gerrit.common.errors.NoSuchEntityException; |
| import com.google.gerrit.server.project.NoSuchChangeException; |
| import com.google.gerrit.server.project.NoSuchProjectException; |
| import com.google.gerrit.server.project.NoSuchRefException; |
| import com.google.gwtjsonrpc.common.AsyncCallback; |
| import com.google.gwtjsonrpc.common.VoidResult; |
| import com.google.gwtorm.server.OrmException; |
| |
| import java.util.concurrent.Callable; |
| |
| /** |
| * Base class for RPC service implementations. |
| * <p> |
| * Typically an RPC service implementation will extend this class and use Guice |
| * injection to manage its state. For example: |
| * |
| * <pre> |
| * class Foo extends Handler<Result> { |
| * interface Factory { |
| * Foo create(... args ...); |
| * } |
| * @Inject |
| * Foo(state, @Assisted args) { ... } |
| * Result get() throws Exception { ... } |
| * } |
| * </pre> |
| * |
| * @param <T> type of result for {@link AsyncCallback#onSuccess(Object)} if the |
| * operation completed successfully. |
| */ |
| public abstract class Handler<T> implements Callable<T> { |
| public static <T> Handler<T> wrap(final Callable<T> r) { |
| return new Handler<T>() { |
| @Override |
| public T call() throws Exception { |
| return r.call(); |
| } |
| }; |
| } |
| |
| /** |
| * Run the operation and pass the result to the callback. |
| * |
| * @param callback callback to receive the result of {@link #call()}. |
| */ |
| public final void to(final AsyncCallback<T> callback) { |
| try { |
| final T r = call(); |
| if (r != null) { |
| callback.onSuccess(r); |
| } |
| } catch (NoSuchProjectException e) { |
| callback.onFailure(new NoSuchEntityException()); |
| |
| } catch (NoSuchRefException e) { |
| callback.onFailure(new NoSuchEntityException()); |
| |
| } catch (NoSuchChangeException e) { |
| callback.onFailure(new NoSuchEntityException()); |
| |
| } catch (OrmException e) { |
| if (e.getCause() instanceof BaseServiceImplementation.Failure) { |
| callback.onFailure(e.getCause().getCause()); |
| |
| } else if (e.getCause() instanceof CorruptEntityException) { |
| callback.onFailure(e.getCause()); |
| |
| } else if (e.getCause() instanceof NoSuchEntityException) { |
| callback.onFailure(e.getCause()); |
| |
| } else { |
| callback.onFailure(e); |
| } |
| } catch (BaseServiceImplementation.Failure e) { |
| callback.onFailure(e.getCause()); |
| } catch (Exception e) { |
| callback.onFailure(e); |
| } |
| } |
| |
| /** |
| * Compute the operation result. |
| * |
| * @return the result of the operation. Return {@link VoidResult#INSTANCE} if |
| * there is no meaningful return value for the operation. |
| * @throws Exception the operation failed. The caller will log the exception |
| * and the stack trace, if it is worth logging on the server side. |
| */ |
| public abstract T call() throws Exception; |
| } |