/thirdparty/breakpad/third_party/protobuf/protobuf/java/src/main/java/com/google/protobuf/RpcUtil.java
http://github.com/tomahawk-player/tomahawk · Java · 135 lines · 56 code · 10 blank · 69 comment · 1 complexity · 25ee19f03ac22a00a670f324cb267725 MD5 · raw file
- // Protocol Buffers - Google's data interchange format
- // Copyright 2008 Google Inc. All rights reserved.
- // http://code.google.com/p/protobuf/
- //
- // Redistribution and use in source and binary forms, with or without
- // modification, are permitted provided that the following conditions are
- // met:
- //
- // * Redistributions of source code must retain the above copyright
- // notice, this list of conditions and the following disclaimer.
- // * Redistributions in binary form must reproduce the above
- // copyright notice, this list of conditions and the following disclaimer
- // in the documentation and/or other materials provided with the
- // distribution.
- // * Neither the name of Google Inc. nor the names of its
- // contributors may be used to endorse or promote products derived from
- // this software without specific prior written permission.
- //
- // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
- // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
- // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
- // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- package com.google.protobuf;
- /**
- * Grab-bag of utility functions useful when dealing with RPCs.
- *
- * @author kenton@google.com Kenton Varda
- */
- public final class RpcUtil {
- private RpcUtil() {}
- /**
- * Take an {@code RpcCallback<Message>} and convert it to an
- * {@code RpcCallback} accepting a specific message type. This is always
- * type-safe (parameter type contravariance).
- */
- @SuppressWarnings("unchecked")
- public static <Type extends Message> RpcCallback<Type>
- specializeCallback(final RpcCallback<Message> originalCallback) {
- return (RpcCallback<Type>)originalCallback;
- // The above cast works, but only due to technical details of the Java
- // implementation. A more theoretically correct -- but less efficient --
- // implementation would be as follows:
- // return new RpcCallback<Type>() {
- // public void run(Type parameter) {
- // originalCallback.run(parameter);
- // }
- // };
- }
- /**
- * Take an {@code RpcCallback} accepting a specific message type and convert
- * it to an {@code RpcCallback<Message>}. The generalized callback will
- * accept any message object which has the same descriptor, and will convert
- * it to the correct class before calling the original callback. However,
- * if the generalized callback is given a message with a different descriptor,
- * an exception will be thrown.
- */
- public static <Type extends Message>
- RpcCallback<Message> generalizeCallback(
- final RpcCallback<Type> originalCallback,
- final Class<Type> originalClass,
- final Type defaultInstance) {
- return new RpcCallback<Message>() {
- public void run(final Message parameter) {
- Type typedParameter;
- try {
- typedParameter = originalClass.cast(parameter);
- } catch (ClassCastException ignored) {
- typedParameter = copyAsType(defaultInstance, parameter);
- }
- originalCallback.run(typedParameter);
- }
- };
- }
- /**
- * Creates a new message of type "Type" which is a copy of "source". "source"
- * must have the same descriptor but may be a different class (e.g.
- * DynamicMessage).
- */
- @SuppressWarnings("unchecked")
- private static <Type extends Message> Type copyAsType(
- final Type typeDefaultInstance, final Message source) {
- return (Type)typeDefaultInstance.newBuilderForType()
- .mergeFrom(source)
- .build();
- }
- /**
- * Creates a callback which can only be called once. This may be useful for
- * security, when passing a callback to untrusted code: most callbacks do
- * not expect to be called more than once, so doing so may expose bugs if it
- * is not prevented.
- */
- public static <ParameterType>
- RpcCallback<ParameterType> newOneTimeCallback(
- final RpcCallback<ParameterType> originalCallback) {
- return new RpcCallback<ParameterType>() {
- private boolean alreadyCalled = false;
- public void run(final ParameterType parameter) {
- synchronized(this) {
- if (alreadyCalled) {
- throw new AlreadyCalledException();
- }
- alreadyCalled = true;
- }
- originalCallback.run(parameter);
- }
- };
- }
- /**
- * Exception thrown when a one-time callback is called more than once.
- */
- public static final class AlreadyCalledException extends RuntimeException {
- private static final long serialVersionUID = 5469741279507848266L;
- public AlreadyCalledException() {
- super("This RpcCallback was already called and cannot be called " +
- "multiple times.");
- }
- }
- }