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Eliminates potential cyclic entry into CSMachine during its -dealloc.

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Explicit cause: dealloc calls close_output(). That may decide to flush work, indiscriminately. Some of the flushed work might be audio generation. Audio generation might cause the audio queue to react with an out-of-data announcement. Which would cause a fresh attempt to update the CSMachine.
This commit is contained in:
Thomas Harte 2017-08-31 21:22:23 -04:00
parent c88d627b4e
commit f10be2a18a
1 changed files with 33 additions and 8 deletions
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41
OSBindings/Mac/Clock Signal/Machine/CSMachine.mm
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@ -19,26 +19,38 @@
- (void)machineDidChangeClockIsUnlimited;
@end
struct SpeakerDelegate: public Outputs::Speaker::Delegate {
__weak CSMachine *machine;
struct LockProtectedDelegate {
// Contractual promise is: machine — the pointer **and** the object ** — may be accessed only
// in sections protected by the machineAccessLock;
NSLock *machineAccessLock;
__unsafe_unretained CSMachine *machine;
};
struct SpeakerDelegate: public Outputs::Speaker::Delegate, public LockProtectedDelegate {
void speaker_did_complete_samples(Outputs::Speaker *speaker, const std::vector<int16_t> &buffer) {
[machineAccessLock lock];
[machine speaker:speaker didCompleteSamples:buffer.data() length:(int)buffer.size()];
[machineAccessLock unlock];
}
};
struct MachineDelegate: CRTMachine::Machine::Delegate {
__weak CSMachine *machine;
struct MachineDelegate: CRTMachine::Machine::Delegate, public LockProtectedDelegate {
void machine_did_change_clock_rate(CRTMachine::Machine *sender) {
[machineAccessLock lock];
[machine machineDidChangeClockRate];
[machineAccessLock unlock];
}
void machine_did_change_clock_is_unlimited(CRTMachine::Machine *sender) {
[machineAccessLock lock];
[machine machineDidChangeClockIsUnlimited];
[machineAccessLock unlock];
}
};
@implementation CSMachine {
SpeakerDelegate _speakerDelegate;
MachineDelegate _machineDelegate;
NSLock *_delegateMachineAccessLock;
CRTMachine::Machine *_machine;
}
@ -46,8 +58,12 @@ struct MachineDelegate: CRTMachine::Machine::Delegate {
self = [super init];
if(self) {
_machine = (CRTMachine::Machine *)machine;
_delegateMachineAccessLock = [[NSLock alloc] init];
_machineDelegate.machine = self;
_speakerDelegate.machine = self;
_machineDelegate.machineAccessLock = _delegateMachineAccessLock;
_speakerDelegate.machineAccessLock = _delegateMachineAccessLock;
_machine->set_delegate(&_machineDelegate);
}
@ -67,6 +83,17 @@ struct MachineDelegate: CRTMachine::Machine::Delegate {
}
- (void)dealloc {
// The two delegate's references to this machine are nilled out here because close_output may result
// in a data flush, which might cause an audio callback, which could cause the audio queue to decide
// that it's out of data, resulting in an attempt further to run the machine while it is dealloc'ing.
//
// They are nilled inside an explicit lock because that allows the delegates to protect their entire
// call into the machine, not just the pointer access.
[_delegateMachineAccessLock lock];
_machineDelegate.machine = nil;
_speakerDelegate.machine = nil;
[_delegateMachineAccessLock unlock];
[_view performWithGLContext:^{
@synchronized(self) {
_machine->close_output();
@ -77,8 +104,7 @@ struct MachineDelegate: CRTMachine::Machine::Delegate {
- (float)idealSamplingRateFromRange:(NSRange)range {
@synchronized(self) {
std::shared_ptr<Outputs::Speaker> speaker = _machine->get_speaker();
if(speaker)
{
if(speaker) {
return speaker->get_ideal_clock_rate_in_range((float)range.location, (float)(range.location + range.length));
}
return 0;
@ -94,8 +120,7 @@ struct MachineDelegate: CRTMachine::Machine::Delegate {
- (BOOL)setSpeakerDelegate:(Outputs::Speaker::Delegate *)delegate sampleRate:(float)sampleRate bufferSize:(NSUInteger)bufferSize {
@synchronized(self) {
std::shared_ptr<Outputs::Speaker> speaker = _machine->get_speaker();
if(speaker)
{
if(speaker) {
speaker->set_output_rate(sampleRate, (int)bufferSize);
speaker->set_delegate(delegate);
return YES;