com.google.gerrit.server.util.ThreadLocalRequestScopePropagator Maven / Gradle / Ivy
// 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.gerrit.server.config.RequestScopedReviewDbProvider;
import com.google.inject.OutOfScopeException;
import com.google.inject.Provider;
import com.google.inject.Scope;
import java.util.concurrent.Callable;
/**
* {@link RequestScopePropagator} implementation for request scopes based on a {@link ThreadLocal}
* context.
*
* @param "context" type stored in the {@link ThreadLocal}.
*/
public abstract class ThreadLocalRequestScopePropagator extends RequestScopePropagator {
private final ThreadLocal threadLocal;
protected ThreadLocalRequestScopePropagator(
Scope scope,
ThreadLocal threadLocal,
ThreadLocalRequestContext local,
Provider dbProviderProvider) {
super(scope, local, dbProviderProvider);
this.threadLocal = threadLocal;
}
/** @see RequestScopePropagator#wrap(Callable) */
@Override
protected final Callable wrapImpl(Callable callable) {
C ctx = continuingContext(requireContext());
return () -> {
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.
*
* 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);
}