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/*
*
* Copyright 2015, Google Inc.
* All rights reserved.
*
* 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.
*
*/
#import <Foundation/Foundation.h>
#import "GRXWriter.h"
#import "GRXWriteable.h"
/**
* This is a thread-safe wrapper over a GRXWriteable instance. It lets one enqueue calls to a
* GRXWriteable instance for the main thread, 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 from the main thread (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 NS_DESIGNATED_INITIALIZER;
/**
* Enqueues writeValue: to be sent to the writeable in the main thread.
* The passed handler is invoked from the main thread after writeValue: returns.
*/
- (void)enqueueValue:(id)value completionHandler:(void (^)())handler;
/**
* Enqueues writesFinishedWithError:nil to be sent to the writeable in the main thread. 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 main thread, 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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