mirror of https://github.com/grpc/grpc.git
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/*
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* |
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* Copyright 2015, Google Inc. |
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* All rights reserved. |
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* |
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* Redistribution and use in source and binary forms, with or without |
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* modification, are permitted provided that the following conditions are |
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* met: |
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* |
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* * Redistributions of source code must retain the above copyright |
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* notice, this list of conditions and the following disclaimer. |
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* * Redistributions in binary form must reproduce the above |
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* copyright notice, this list of conditions and the following disclaimer |
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* in the documentation and/or other materials provided with the |
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* distribution. |
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* * Neither the name of Google Inc. nor the names of its |
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* contributors may be used to endorse or promote products derived from |
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* this software without specific prior written permission. |
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* |
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR |
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* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT |
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* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
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* |
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*/ |
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#import <Foundation/Foundation.h> |
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#import "GRXWriteable.h" |
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#import "GRXWriter.h" |
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// A buffered pipe is a Writeable that also acts as a Writer (to whichever other writeable is passed
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// to -startWithWriteable:).
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// Once it is started, whatever values are written into it (via -didReceiveValue:) will be
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// propagated immediately, unless flow control prevents it.
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// If it is throttled and keeps receiving values, as well as if it receives values before being
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// started, it will buffer them and propagate them in order as soon as its state becomes
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// GRXWriterStateStarted.
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// If it receives an error (via -didFinishWithError:), it will drop any buffered values and
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// propagate the error immediately.
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@interface GRXBufferedPipe : NSObject<GRXWriteable, GRXWriter> |
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// Convenience constructor.
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+ (instancetype)pipe; |
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@end |
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/* |
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* |
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* Copyright 2015, Google Inc. |
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* All rights reserved. |
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* |
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* Redistribution and use in source and binary forms, with or without |
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* modification, are permitted provided that the following conditions are |
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* met: |
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* |
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* * Redistributions of source code must retain the above copyright |
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* notice, this list of conditions and the following disclaimer. |
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* * Redistributions in binary form must reproduce the above |
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* copyright notice, this list of conditions and the following disclaimer |
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* in the documentation and/or other materials provided with the |
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* distribution. |
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* * Neither the name of Google Inc. nor the names of its |
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* contributors may be used to endorse or promote products derived from |
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* this software without specific prior written permission. |
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* |
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR |
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* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT |
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* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
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* |
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*/ |
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#import "GRXBufferedPipe.h" |
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@implementation GRXBufferedPipe { |
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id<GRXWriteable> _writeable; |
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NSMutableArray *_queue; |
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BOOL _inputIsFinished; |
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NSError *_errorOrNil; |
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} |
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@synthesize state = _state; |
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+ (instancetype)pipe { |
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return [[self alloc] init]; |
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} |
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- (instancetype)init { |
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if (self = [super init]) { |
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_queue = [NSMutableArray array]; |
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_state = GRXWriterStateNotStarted; |
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} |
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return self; |
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} |
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- (id)popValue { |
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id value = _queue[0]; |
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[_queue removeObjectAtIndex:0]; |
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return value; |
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} |
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- (void)writeBufferUntilPausedOrStopped { |
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while (_state == GRXWriterStateStarted && _queue.count > 0) { |
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[_writeable didReceiveValue:[self popValue]]; |
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} |
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if (_inputIsFinished && _queue.count == 0) { |
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// Our writer finished normally while we were paused or not-started-yet. |
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[self finishWithError:_errorOrNil]; |
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} |
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} |
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#pragma mark GRXWriteable implementation |
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// Returns whether events can be simply propagated to the other end of the pipe. |
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- (BOOL)shouldFastForward { |
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return _state == GRXWriterStateStarted && _queue.count == 0; |
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} |
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- (void)didReceiveValue:(id)value { |
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if (self.shouldFastForward) { |
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// Skip the queue. |
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[_writeable didReceiveValue:value]; |
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} else { |
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// Even if we're paused and with enqueued values, we can't excert back-pressure to our writer. |
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// So just buffer the new value. |
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[_queue addObject:value]; |
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} |
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} |
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- (void)didFinishWithError:(NSError *)errorOrNil { |
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_inputIsFinished = YES; |
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_errorOrNil = errorOrNil; |
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if (errorOrNil || self.shouldFastForward) { |
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// No need to write pending values. |
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[self finishWithError:_errorOrNil]; |
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} |
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} |
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#pragma mark GRXWriter implementation |
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- (void)setState:(GRXWriterState)newState { |
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// Manual transitions are only allowed from the started or paused states. |
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if (_state == GRXWriterStateNotStarted || _state == GRXWriterStateFinished) { |
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return; |
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} |
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switch (newState) { |
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case GRXWriterStateFinished: |
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_state = newState; |
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_queue = nil; |
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// Per GRXWriter's contract, setting the state to Finished manually means one doesn't wish the |
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// writeable to be messaged anymore. |
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_writeable = nil; |
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return; |
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case GRXWriterStatePaused: |
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_state = newState; |
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return; |
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case GRXWriterStateStarted: |
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if (_state == GRXWriterStatePaused) { |
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_state = newState; |
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[self writeBufferUntilPausedOrStopped]; |
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} |
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return; |
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case GRXWriterStateNotStarted: |
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return; |
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} |
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} |
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- (void)startWithWriteable:(id<GRXWriteable>)writeable { |
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_state = GRXWriterStateStarted; |
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_writeable = writeable; |
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[self writeBufferUntilPausedOrStopped]; |
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} |
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- (void)finishWithError:(NSError *)errorOrNil { |
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id<GRXWriteable> writeable = _writeable; |
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self.state = GRXWriterStateFinished; |
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[writeable didFinishWithError:errorOrNil]; |
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} |
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@end |
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