| // Copyright (C) 2012 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.server.util; |
| |
| import com.google.inject.OutOfScopeException; |
| import com.google.inject.Scope; |
| |
| import java.util.concurrent.Callable; |
| |
| /** |
| * {@link RequestScopePropagator} implementation for request scopes based on |
| * a {@link ThreadLocal} context. |
| * |
| * @param <C> "context" type stored in the {@link ThreadLocal}. |
| */ |
| public abstract class ThreadLocalRequestScopePropagator<C> |
| extends RequestScopePropagator { |
| |
| private final ThreadLocal<C> threadLocal; |
| |
| protected ThreadLocalRequestScopePropagator(Scope scope, |
| ThreadLocal<C> threadLocal, ThreadLocalRequestContext local) { |
| super(scope, local); |
| this.threadLocal = threadLocal; |
| } |
| |
| /** |
| * @see RequestScopePropagator#wrap(Callable) |
| */ |
| @Override |
| protected final <T> Callable<T> wrapImpl(final Callable<T> callable) { |
| final C ctx = continuingContext(requireContext()); |
| return new Callable<T>() { |
| @Override |
| public T call() throws Exception { |
| C old = threadLocal.get(); |
| threadLocal.set(ctx); |
| try { |
| return callable.call(); |
| } finally { |
| if (old != null) { |
| threadLocal.set(old); |
| } else { |
| threadLocal.remove(); |
| } |
| } |
| } |
| }; |
| } |
| |
| private C requireContext() { |
| C context = threadLocal.get(); |
| if (context == null) { |
| throw new OutOfScopeException("Cannot access scoped object"); |
| } |
| return context; |
| } |
| |
| /** |
| * Returns a new context object based on the passed in context that has no |
| * request scoped objects initialized. |
| * <p> |
| * Note that some code paths expect request-scoped objects like |
| * {@code CurrentUser} to be constructible starting from just the context |
| * object returned by this method. For example, in the SSH scope, the context |
| * includes the {@code SshSession}, which is used by |
| * {@code SshCurrentUserProvider} to construct a new {@code CurrentUser} in |
| * the new thread. |
| * |
| * @param ctx the context to continue. |
| * @return a new context. |
| */ |
| protected abstract C continuingContext(C ctx); |
| } |