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/*
*
* Copyright 2015 gRPC authors.
*
* 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.
*
*/
#import <Foundation/Foundation.h>
#import "GRXWriteable.h"
#import "GRXWriter.h"
/**
* This is a thread-safe wrapper over a GRXWriteable instance. It lets one enqueue calls to a
* GRXWriteable instance for the thread user provided, guaranteeing that writesFinishedWithError: is
* the last message sent to it (no matter what messages are sent to the wrapper, in what order, nor
* from which thread). It also guarantees that, if cancelWithError: is called (e.g. by the app
* cancelling the writes), no further messages are sent to the writeable except
* writesFinishedWithError:.
*
* TODO(jcanizales): Let the user specify another queue for the writeable callbacks.
*/
@interface GRXConcurrentWriteable : NSObject
/**
* The GRXWriteable passed is the wrapped writeable.
* The GRXWriteable instance is retained until writesFinishedWithError: is sent to it, and released
* after that.
*/
- (instancetype)initWithWriteable:(id<GRXWriteable>)writeable
dispatchQueue:(dispatch_queue_t)queue NS_DESIGNATED_INITIALIZER;
- (instancetype)initWithWriteable:(id<GRXWriteable>)writeable;
/**
* Enqueues writeValue: to be sent to the writeable from the designated dispatch queue.
* The passed handler is invoked from designated dispatch queue after writeValue: returns.
*/
- (void)enqueueValue:(id)value completionHandler:(void (^)(void))handler;
/**
* Enqueues writesFinishedWithError:nil to be sent to the writeable in the designated dispatch
* queue. After that message is sent to the writeable, all other methods of this object are
* effectively noops.
*/
- (void)enqueueSuccessfulCompletion;
/**
* If the writeable has not yet received a writesFinishedWithError: message, this will enqueue one
* to be sent to it in the designated dispatch queue, and cancel all other pending messages to the
* writeable enqueued by this object (both past and future).
* The error argument cannot be nil.
*/
- (void)cancelWithError:(NSError *)error;
/**
* Cancels all pending messages to the writeable enqueued by this object (both past and future).
* Because the writeable won't receive writesFinishedWithError:, this also releases the writeable.
*/
- (void)cancelSilently;
@end
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