diff options
Diffstat (limited to 'src/objective-c/RxLibrary')
-rw-r--r-- | src/objective-c/RxLibrary/GRXBufferedPipe.h | 3 | ||||
-rw-r--r-- | src/objective-c/RxLibrary/GRXBufferedPipe.m | 21 | ||||
-rw-r--r-- | src/objective-c/RxLibrary/GRXConcurrentWriteable.h | 21 | ||||
-rw-r--r-- | src/objective-c/RxLibrary/GRXConcurrentWriteable.m | 102 | ||||
-rw-r--r-- | src/objective-c/RxLibrary/GRXForwardingWriter.h | 6 | ||||
-rw-r--r-- | src/objective-c/RxLibrary/GRXForwardingWriter.m | 55 | ||||
-rw-r--r-- | src/objective-c/RxLibrary/GRXImmediateSingleWriter.h | 2 | ||||
-rw-r--r-- | src/objective-c/RxLibrary/GRXImmediateSingleWriter.m | 30 | ||||
-rw-r--r-- | src/objective-c/RxLibrary/GRXWriter.h | 4 |
9 files changed, 130 insertions, 114 deletions
diff --git a/src/objective-c/RxLibrary/GRXBufferedPipe.h b/src/objective-c/RxLibrary/GRXBufferedPipe.h index a871ea895a..ae08cc315b 100644 --- a/src/objective-c/RxLibrary/GRXBufferedPipe.h +++ b/src/objective-c/RxLibrary/GRXBufferedPipe.h @@ -36,8 +36,7 @@ * crash. If you want to react to flow control signals to prevent that, instead of using this class * you can implement an object that conforms to GRXWriter. * - * Thread-safety: - * The methods of an object of this class should not be called concurrently from different threads. + * Thread-safety: the methods of this class are thread-safe. */ @interface GRXBufferedPipe : GRXWriter<GRXWriteable> diff --git a/src/objective-c/RxLibrary/GRXBufferedPipe.m b/src/objective-c/RxLibrary/GRXBufferedPipe.m index 546d46cba3..74e2f03da6 100644 --- a/src/objective-c/RxLibrary/GRXBufferedPipe.m +++ b/src/objective-c/RxLibrary/GRXBufferedPipe.m @@ -51,16 +51,22 @@ // We need a copy, so that it doesn't mutate before it's written at the other end of the pipe. value = [value copy]; } - __weak GRXBufferedPipe *weakSelf = self; dispatch_async(_writeQueue, ^(void) { - [weakSelf.writeable writeValue:value]; + @synchronized(self) { + if (self->_state == GRXWriterStateFinished) { + return; + } + [self.writeable writeValue:value]; + } }); } - (void)writesFinishedWithError:(NSError *)errorOrNil { - __weak GRXBufferedPipe *weakSelf = self; dispatch_async(_writeQueue, ^{ - [weakSelf finishWithError:errorOrNil]; + if (self->_state == GRXWriterStateFinished) { + return; + } + [self finishWithError:errorOrNil]; }); } @@ -100,14 +106,15 @@ } - (void)startWithWriteable:(id<GRXWriteable>)writeable { - self.writeable = writeable; - _state = GRXWriterStateStarted; + @synchronized(self) { + self.writeable = writeable; + _state = GRXWriterStateStarted; + } dispatch_resume(_writeQueue); } - (void)finishWithError:(NSError *)errorOrNil { [self.writeable writesFinishedWithError:errorOrNil]; - self.state = GRXWriterStateFinished; } - (void)dealloc { diff --git a/src/objective-c/RxLibrary/GRXConcurrentWriteable.h b/src/objective-c/RxLibrary/GRXConcurrentWriteable.h index abb831e6fb..5beca9d41e 100644 --- a/src/objective-c/RxLibrary/GRXConcurrentWriteable.h +++ b/src/objective-c/RxLibrary/GRXConcurrentWriteable.h @@ -23,10 +23,10 @@ /** * 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 + * 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. @@ -43,21 +43,22 @@ - (instancetype)initWithWriteable:(id<GRXWriteable>)writeable; /** - * Enqueues writeValue: to be sent to the writeable in the main thread. - * The passed handler is invoked from the main thread after writeValue: returns. + * 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 main thread. After that - * message is sent to the writeable, all other methods of this object are effectively noops. + * 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 main thread, and cancel all other pending messages to the writeable - * enqueued by this object (both past and future). + * 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; diff --git a/src/objective-c/RxLibrary/GRXConcurrentWriteable.m b/src/objective-c/RxLibrary/GRXConcurrentWriteable.m index 81ccc3fbce..115195463d 100644 --- a/src/objective-c/RxLibrary/GRXConcurrentWriteable.m +++ b/src/objective-c/RxLibrary/GRXConcurrentWriteable.m @@ -27,8 +27,15 @@ @implementation GRXConcurrentWriteable { dispatch_queue_t _writeableQueue; - // This ensures that writesFinishedWithError: is only sent once to the writeable. + + // This ivar ensures that writesFinishedWithError: is only sent once to the writeable. Protected + // by _writeableQueue. BOOL _alreadyFinished; + + // This ivar ensures that a cancelWithError: call prevents further values to be sent to + // self.writeable. It must support manipulation outside of _writeableQueue and thus needs to be + // protected by self lock. + BOOL _cancelled; } - (instancetype)init { @@ -41,6 +48,8 @@ if (self = [super init]) { _writeableQueue = queue; _writeable = writeable; + _alreadyFinished = NO; + _cancelled = NO; } return self; } @@ -51,78 +60,63 @@ - (void)enqueueValue:(id)value completionHandler:(void (^)(void))handler { dispatch_async(_writeableQueue, ^{ - // We're racing a possible cancellation performed by another thread. To turn all already- - // enqueued messages into noops, cancellation nillifies the writeable property. If we get it - // before it's nil, we won the race. - id<GRXWriteable> writeable = self.writeable; - if (writeable) { - [writeable writeValue:value]; - handler(); + if (self->_alreadyFinished) { + return; + } + + @synchronized(self) { + if (self->_cancelled) { + return; + } } + + [self.writeable writeValue:value]; + handler(); }); } - (void)enqueueSuccessfulCompletion { - __weak typeof(self) weakSelf = self; dispatch_async(_writeableQueue, ^{ - typeof(self) strongSelf = weakSelf; - if (strongSelf) { - BOOL finished = NO; - @synchronized(strongSelf) { - if (!strongSelf->_alreadyFinished) { - strongSelf->_alreadyFinished = YES; - } else { - finished = YES; - } - } - if (!finished) { - // Cancellation is now impossible. None of the other three blocks can run concurrently with - // this one. - [strongSelf.writeable writesFinishedWithError:nil]; - // Skip any possible message to the wrapped writeable enqueued after this one. - strongSelf.writeable = nil; + if (self->_alreadyFinished) { + return; + } + @synchronized(self) { + if (self->_cancelled) { + return; } } + [self.writeable writesFinishedWithError:nil]; + + // Skip any possible message to the wrapped writeable enqueued after this one. + self->_alreadyFinished = YES; + self.writeable = nil; }); } - (void)cancelWithError:(NSError *)error { - NSAssert(error, @"For a successful completion, use enqueueSuccessfulCompletion."); - BOOL finished = NO; + NSAssert(error != nil, @"For a successful completion, use enqueueSuccessfulCompletion."); @synchronized(self) { - if (!_alreadyFinished) { - _alreadyFinished = YES; - } else { - finished = YES; - } + self->_cancelled = YES; } - if (!finished) { - // Skip any of the still-enqueued messages to the wrapped writeable. We use the atomic setter to - // nillify writeable because we might be running concurrently with the blocks in - // _writeableQueue, and assignment with ARC isn't atomic. - id<GRXWriteable> writeable = self.writeable; - self.writeable = nil; + dispatch_async(_writeableQueue, ^{ + if (self->_alreadyFinished) { + // a cancel or a successful completion is already issued + return; + } + [self.writeable writesFinishedWithError:error]; - dispatch_async(_writeableQueue, ^{ - [writeable writesFinishedWithError:error]; - }); - } + // Skip any possible message to the wrapped writeable enqueued after this one. + self->_alreadyFinished = YES; + self.writeable = nil; + }); } - (void)cancelSilently { - BOOL finished = NO; - @synchronized(self) { - if (!_alreadyFinished) { - _alreadyFinished = YES; - } else { - finished = YES; + dispatch_async(_writeableQueue, ^{ + if (self->_alreadyFinished) { + return; } - } - if (!finished) { - // Skip any of the still-enqueued messages to the wrapped writeable. We use the atomic setter to - // nillify writeable because we might be running concurrently with the blocks in - // _writeableQueue, and assignment with ARC isn't atomic. self.writeable = nil; - } + }); } @end diff --git a/src/objective-c/RxLibrary/GRXForwardingWriter.h b/src/objective-c/RxLibrary/GRXForwardingWriter.h index 3814ff8831..00366b6416 100644 --- a/src/objective-c/RxLibrary/GRXForwardingWriter.h +++ b/src/objective-c/RxLibrary/GRXForwardingWriter.h @@ -25,11 +25,7 @@ * input writer, and for classes that represent objects with input and * output sequences of values, like an RPC. * - * Thread-safety: - * All messages sent to this object need to be serialized. When it is started, the writer it wraps - * is started in the same thread. Manual state changes are propagated to the wrapped writer in the - * same thread too. Importantly, all messages the wrapped writer sends to its writeable need to be - * serialized with any message sent to this object. + * Thread-safety: the methods of this class are thread safe. */ @interface GRXForwardingWriter : GRXWriter - (instancetype)initWithWriter:(GRXWriter *)writer NS_DESIGNATED_INITIALIZER; diff --git a/src/objective-c/RxLibrary/GRXForwardingWriter.m b/src/objective-c/RxLibrary/GRXForwardingWriter.m index 3e522ef24e..27ac0acdff 100644 --- a/src/objective-c/RxLibrary/GRXForwardingWriter.m +++ b/src/objective-c/RxLibrary/GRXForwardingWriter.m @@ -54,48 +54,65 @@ [writeable writesFinishedWithError:errorOrNil]; } -// This is used to stop the input writer. It nillifies our reference to it -// to release it. -- (void)finishInput { - GRXWriter *writer = _writer; - _writer = nil; - writer.state = GRXWriterStateFinished; -} - #pragma mark GRXWriteable implementation - (void)writeValue:(id)value { - [_writeable writeValue:value]; + @synchronized(self) { + [_writeable writeValue:value]; + } } - (void)writesFinishedWithError:(NSError *)errorOrNil { - _writer = nil; - [self finishOutputWithError:errorOrNil]; + @synchronized(self) { + _writer = nil; + [self finishOutputWithError:errorOrNil]; + } } #pragma mark GRXWriter implementation - (GRXWriterState)state { - return _writer ? _writer.state : GRXWriterStateFinished; + GRXWriter *copiedWriter; + @synchronized(self) { + copiedWriter = _writer; + } + return copiedWriter ? copiedWriter.state : GRXWriterStateFinished; } - (void)setState:(GRXWriterState)state { + GRXWriter *copiedWriter = nil; if (state == GRXWriterStateFinished) { - _writeable = nil; - [self finishInput]; + @synchronized(self) { + _writeable = nil; + copiedWriter = _writer; + _writer = nil; + } + copiedWriter.state = GRXWriterStateFinished; } else { - _writer.state = state; + @synchronized(self) { + copiedWriter = _writer; + } + copiedWriter.state = state; } } - (void)startWithWriteable:(id<GRXWriteable>)writeable { - _writeable = writeable; - [_writer startWithWriteable:self]; + GRXWriter *copiedWriter = nil; + @synchronized(self) { + _writeable = writeable; + copiedWriter = _writer; + } + [copiedWriter startWithWriteable:self]; } - (void)finishWithError:(NSError *)errorOrNil { - [self finishOutputWithError:errorOrNil]; - [self finishInput]; + GRXWriter *copiedWriter = nil; + @synchronized(self) { + [self finishOutputWithError:errorOrNil]; + copiedWriter = _writer; + _writer = nil; + } + copiedWriter.state = GRXWriterStateFinished; } @end diff --git a/src/objective-c/RxLibrary/GRXImmediateSingleWriter.h b/src/objective-c/RxLibrary/GRXImmediateSingleWriter.h index 601abdc6b9..2fa38b3dce 100644 --- a/src/objective-c/RxLibrary/GRXImmediateSingleWriter.h +++ b/src/objective-c/RxLibrary/GRXImmediateSingleWriter.h @@ -23,6 +23,8 @@ /** * Utility to construct GRXWriter instances from values that are immediately available when * required. + * + * Thread safety: the methods of this class are thread safe. */ @interface GRXImmediateSingleWriter : GRXImmediateWriter diff --git a/src/objective-c/RxLibrary/GRXImmediateSingleWriter.m b/src/objective-c/RxLibrary/GRXImmediateSingleWriter.m index 3126ae4bd1..079c11b94f 100644 --- a/src/objective-c/RxLibrary/GRXImmediateSingleWriter.m +++ b/src/objective-c/RxLibrary/GRXImmediateSingleWriter.m @@ -20,7 +20,6 @@ @implementation GRXImmediateSingleWriter { id _value; - id<GRXWriteable> _writeable; } @synthesize state = _state; @@ -38,17 +37,16 @@ } - (void)startWithWriteable:(id<GRXWriteable>)writeable { - _state = GRXWriterStateStarted; - _writeable = writeable; - [writeable writeValue:_value]; - [self finish]; -} - -- (void)finish { - _state = GRXWriterStateFinished; - _value = nil; - id<GRXWriteable> writeable = _writeable; - _writeable = nil; + id copiedValue = nil; + @synchronized(self) { + if (_state != GRXWriterStateNotStarted) { + return; + } + copiedValue = _value; + _value = nil; + _state = GRXWriterStateFinished; + } + [writeable writeValue:copiedValue]; [writeable writesFinishedWithError:nil]; } @@ -65,9 +63,11 @@ // the original \a map function returns a new Writer of another type. So we // need to override this function here. - (GRXWriter *)map:(id (^)(id))map { - // Since _value is available when creating the object, we can simply - // apply the map and store the output. - _value = map(_value); + @synchronized(self) { + // Since _value is available when creating the object, we can simply + // apply the map and store the output. + _value = map(_value); + } return self; } diff --git a/src/objective-c/RxLibrary/GRXWriter.h b/src/objective-c/RxLibrary/GRXWriter.h index 5d99583a92..df4c80c28d 100644 --- a/src/objective-c/RxLibrary/GRXWriter.h +++ b/src/objective-c/RxLibrary/GRXWriter.h @@ -80,9 +80,9 @@ typedef NS_ENUM(NSInteger, GRXWriterState) { * This property can be used to query the current state of the writer, which determines how it might * currently use its writeable. Some state transitions can be triggered by setting this property to * the corresponding value, and that's useful for advanced use cases like pausing an writer. For - * more details, see the documentation of the enum further down. + * more details, see the documentation of the enum further down. The property is thread safe. */ -@property(nonatomic) GRXWriterState state; +@property GRXWriterState state; /** * Transition to the Started state, and start sending messages to the writeable (a reference to it |