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// Protocol Buffers - Google's data interchange format
// Copyright 2008 Google Inc. All rights reserved.
//
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file or at
// https://developers.google.com/open-source/licenses/bsd
package com.google.protobuf;
/**
* An {@code RpcController} mediates a single method call. The primary purpose of the controller is
* to provide a way to manipulate settings specific to the RPC implementation and to find out about
* RPC-level errors.
*
* Starting with version 2.3.0, RPC implementations should not try to build on this, but should
* instead provide code generator plugins which generate code specific to the particular RPC
* implementation. This way the generated code can be more appropriate for the implementation in use
* and can avoid unnecessary layers of indirection.
*
*
The methods provided by the {@code RpcController} interface are intended to be a "least common
* denominator" set of features which we expect all implementations to support. Specific
* implementations may provide more advanced features (e.g. deadline propagation).
*
* @author [email protected] Kenton Varda
*/
public interface RpcController {
// -----------------------------------------------------------------
// These calls may be made from the client side only. Their results
// are undefined on the server side (may throw RuntimeExceptions).
/**
* Resets the RpcController to its initial state so that it may be reused in a new call. This can
* be called from the client side only. It must not be called while an RPC is in progress.
*/
void reset();
/**
* After a call has finished, returns true if the call failed. The possible reasons for failure
* depend on the RPC implementation. {@code failed()} most only be called on the client side, and
* must not be called before a call has finished.
*/
boolean failed();
/** If {@code failed()} is {@code true}, returns a human-readable description of the error. */
String errorText();
/**
* Advises the RPC system that the caller desires that the RPC call be canceled. The RPC system
* may cancel it immediately, may wait awhile and then cancel it, or may not even cancel the call
* at all. If the call is canceled, the "done" callback will still be called and the RpcController
* will indicate that the call failed at that time.
*/
void startCancel();
// -----------------------------------------------------------------
// These calls may be made from the server side only. Their results
// are undefined on the client side (may throw RuntimeExceptions).
/**
* Causes {@code failed()} to return true on the client side. {@code reason} will be incorporated
* into the message returned by {@code errorText()}. If you find you need to return
* machine-readable information about failures, you should incorporate it into your response
* protocol buffer and should NOT call {@code setFailed()}.
*/
void setFailed(String reason);
/**
* If {@code true}, indicates that the client canceled the RPC, so the server may as well give up
* on replying to it. This method must be called on the server side only. The server should still
* call the final "done" callback.
*/
boolean isCanceled();
/**
* Asks that the given callback be called when the RPC is canceled. The parameter passed to the
* callback will always be {@code null}. The callback will always be called exactly once. If the
* RPC completes without being canceled, the callback will be called after completion. If the RPC
* has already been canceled when NotifyOnCancel() is called, the callback will be called
* immediately.
*
*
{@code notifyOnCancel()} must be called no more than once per request. It must be called on
* the server side only.
*/
void notifyOnCancel(RpcCallback