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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 "GRXBufferedPipe.h"
@interface GRXBufferedPipe ()
@property(atomic) id<GRXWriteable> writeable;
@end
@implementation GRXBufferedPipe {
NSError *_errorOrNil;
dispatch_queue_t _writeQueue;
}
@synthesize state = _state;
+ (instancetype)pipe {
return [[self alloc] init];
}
- (instancetype)init {
if (self = [super init]) {
_state = GRXWriterStateNotStarted;
_writeQueue = dispatch_queue_create(NULL, DISPATCH_QUEUE_SERIAL);
dispatch_suspend(_writeQueue);
}
return self;
}
#pragma mark GRXWriteable implementation
- (void)writeValue:(id)value {
if ([value respondsToSelector:@selector(copy)]) {
// Even if we're paused and with enqueued values, we can't excert back-pressure to our writer.
// So just buffer the new value.
// We need a copy, so that it doesn't mutate before it's written at the other end of the pipe.
value = [value copy];
}
dispatch_async(_writeQueue, ^(void) {
@synchronized(self) {
if (self->_state == GRXWriterStateFinished) {
return;
}
[self.writeable writeValue:value];
}
});
}
- (void)writesFinishedWithError:(NSError *)errorOrNil {
dispatch_async(_writeQueue, ^{
if (self->_state == GRXWriterStateFinished) {
return;
}
[self finishWithError:errorOrNil];
});
}
#pragma mark GRXWriter implementation
- (void)setState:(GRXWriterState)newState {
@synchronized(self) {
// Manual transitions are only allowed from the started or paused states.
if (_state == GRXWriterStateNotStarted || _state == GRXWriterStateFinished) {
return;
}
switch (newState) {
case GRXWriterStateFinished:
self.writeable = nil;
if (_state == GRXWriterStatePaused) {
dispatch_resume(_writeQueue);
}
_state = newState;
return;
case GRXWriterStatePaused:
if (_state == GRXWriterStateStarted) {
_state = newState;
dispatch_suspend(_writeQueue);
}
return;
case GRXWriterStateStarted:
if (_state == GRXWriterStatePaused) {
_state = newState;
dispatch_resume(_writeQueue);
}
return;
case GRXWriterStateNotStarted:
return;
}
}
}
- (void)startWithWriteable:(id<GRXWriteable>)writeable {
@synchronized(self) {
self.writeable = writeable;
_state = GRXWriterStateStarted;
}
dispatch_resume(_writeQueue);
}
- (void)finishWithError:(NSError *)errorOrNil {
[self.writeable writesFinishedWithError:errorOrNil];
}
- (void)dealloc {
GRXWriterState state = self.state;
if (state == GRXWriterStateNotStarted || state == GRXWriterStatePaused) {
dispatch_resume(_writeQueue);
}
}
@end
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