[Audio Threads] Change workgroup system again

Now it allocates audio workgroups per thread, using work slices like the
Apple documentation describes for asynchronous threads.

Signed-off-by: Christopher Snowhill <kode54@gmail.com>

Audio/Chain/ConverterNode.mm

@@ -430,9 +430,11 @@ static void convert_be_to_le(uint8_t *buffer, size_t bitsPerSample, size_t bytes
 		while(paused) {
 			usleep(500);
 		}
+		[self startWorkslice];
 		@autoreleasepool {
 			amountConverted = [self convert:writeBuf amount:CHUNK_SIZE];
 		}
+		[self endWorkslice];
 		if(!amountConverted) {
 			if(paused) {
 				continue;

Audio/Chain/InputNode.m

@@ -178,9 +178,11 @@
 
 			int framesToRead = CHUNK_SIZE - amountInBuffer;
 			int framesRead;
+			[self startWorkslice];
 			@autoreleasepool {
 				framesRead = [decoder readAudio:((char *)inputBuffer) + bytesInBuffer frames:framesToRead];
 			}
+			[self endWorkslice];
 
 			if(framesRead > 0 && !seekError) {
 				amountInBuffer += framesRead;

Audio/Chain/Node.h

@@ -34,7 +34,8 @@
 	uint32_t nodeChannelConfig;
 	BOOL nodeLossless;
 
-	os_workgroup_t wg;
+	int64_t intervalMachLength;
+	os_workgroup_interval_t workgroup, wg;
 	os_workgroup_join_token_s wgToken;
 }
 - (id _Nullable)initWithController:(id _Nonnull)c previous:(id _Nullable)p;
@@ -49,6 +50,8 @@
 
 - (void)followWorkgroup;
 - (void)leaveWorkgroup;
+- (void)startWorkslice;
+- (void)endWorkslice;
 
 - (void)launchThread;
 

Audio/Chain/Node.m

@@ -13,6 +13,20 @@
 
 #import "OutputCoreAudio.h"
 
+#import <mach/mach_time.h>
+
+// This workgroup attribute isn't currently used. Set it to NULL.
+static os_workgroup_attr_t _Nullable attr = nil;
+
+// One nanosecond in seconds.
+static const double kOneNanosecond = 1.0e9;
+
+// The I/O interval time in seconds.
+static const double kIOIntervalTime = 0.020;
+
+// The clock identifier that specifies interval timestamps.
+static const os_clockid_t clockId = OS_CLOCK_MACH_ABSOLUTE_TIME;
+
 @implementation Node
 
 - (id)initWithController:(id)c previous:(id)p {
@@ -32,6 +46,21 @@
 		nodeChannelConfig = 0;
 		nodeLossless = NO;
 
+		if(@available(macOS 11, *)) {
+			workgroup = AudioWorkIntervalCreate("Node Work Interval", clockId, attr);
+
+			// Get the mach time info.
+			struct mach_timebase_info timeBaseInfo;
+			mach_timebase_info(&timeBaseInfo);
+
+			// The frequency of the clock is: (timeBaseInfo.denom / timeBaseInfo.numer) * kOneNanosecond
+			const double nanoSecFrequency = (double)(timeBaseInfo.denom) / (double)(timeBaseInfo.numer);
+			const double frequency = nanoSecFrequency * kOneNanosecond;
+
+			// Convert the interval time in seconds to mach time length.
+			intervalMachLength = (int64_t)(kIOIntervalTime * frequency);
+		}
+
 		[self setPreviousNode:p];
 	}
 
@@ -101,11 +130,8 @@
 
 - (void)followWorkgroup {
 	if(@available(macOS 11, *)) {
-		if(currentWorkgroup != wg) {
+		if(!wg) {
-			if(wg) {
+			wg = workgroup;
-				os_workgroup_leave(wg, &wgToken);
-			}
-			wg = currentWorkgroup;
 			if(wg) {
 				int result = os_workgroup_join(wg, &wgToken);
 				if(result == 0) return;
@@ -128,6 +154,30 @@
 	}
 }
 
+- (void)startWorkslice {
+	if(@available(macOS 11, *)) {
+		if(wg) {
+			const uint64_t currentTime = mach_absolute_time();
+			const uint64_t deadline = currentTime + intervalMachLength;
+			int result = os_workgroup_interval_start(wg, currentTime, deadline, nil);
+			if(result != 0) {
+				DLog(@"Deadline error = %d", result);
+			}
+		}
+	}
+}
+
+- (void)endWorkslice {
+	if(@available(macOS 11, *)) {
+		if(wg) {
+			int result = os_workgroup_interval_finish(wg, nil);
+			if(result != 0) {
+				DLog(@"Deadline end error = %d", result);
+			}
+		}
+	}
+}
+
 - (BOOL)peekFormat:(nonnull AudioStreamBasicDescription *)format channelConfig:(nonnull uint32_t *)config {
 	[accessLock lock];
 

Audio/Output/OutputCoreAudio.h

@@ -33,10 +33,6 @@ using std::atomic_long;
 #import <stdio.h>
 #endif
 
-#import <os/workgroup.h>
-
-extern volatile os_workgroup_t currentWorkgroup;
-
 @class OutputNode;
 
 @interface OutputCoreAudio : NSObject {

Audio/Output/OutputCoreAudio.m

@@ -17,8 +17,6 @@
 
 #import <Accelerate/Accelerate.h>
 
-volatile os_workgroup_t currentWorkgroup;
-
 extern void scale_by_volume(float *buffer, size_t count, float volume);
 
 static NSString *CogPlaybackDidBeginNotficiation = @"CogPlaybackDidBeginNotficiation";
@@ -263,21 +261,6 @@ default_device_changed(AudioObjectID inObjectID, UInt32 inNumberAddresses, const
 	NSMutableArray *delayedEvents = [[NSMutableArray alloc] init];
 	BOOL delayedEventsPopped = YES;
 
-	if(@available(macOS 11, *)) {
-		if(currentWorkgroup) {
-			wg = currentWorkgroup;
-			int result = os_workgroup_join(wg, &wgToken);
-			if(result != 0) {
-				if(result == EALREADY) {
-					DLog(@"Output thread already in workgroup");
-				} else {
-					DLog(@"Output thread could not be added to workgroup, error = %d", result);
-				}
-				wg = nil;
-			}
-		}
-	}
-
 	while(!stopping) {
 		if(++eventCount == 48) {
 			[self resetIfOutputChanged];
@@ -363,13 +346,6 @@ default_device_changed(AudioObjectID inObjectID, UInt32 inNumberAddresses, const
 		[writeSemaphore timedWait:5000];
 	}
 
-	if(@available(macOS 11, *)) {
-		if(wg) {
-			os_workgroup_leave(wg, &wgToken);
-			wg = nil;
-		}
-	}
-
 	stopped = YES;
 	if(!stopInvoked)
 		[self stop];
@@ -806,10 +782,6 @@ default_device_changed(AudioObjectID inObjectID, UInt32 inNumberAddresses, const
 
 	visController = [VisualizationController sharedController];
 
-	if(@available(macOS 11, *)) {
-		currentWorkgroup = _au.osWorkgroup;
-	}
-
 	[[NSUserDefaultsController sharedUserDefaultsController] addObserver:self forKeyPath:@"values.outputDevice" options:0 context:NULL];
 	[[NSUserDefaultsController sharedUserDefaultsController] addObserver:self forKeyPath:@"values.GraphicEQenable" options:0 context:NULL];
 	[[NSUserDefaultsController sharedUserDefaultsController] addObserver:self forKeyPath:@"values.eqPreamp" options:(NSKeyValueObservingOptionInitial | NSKeyValueObservingOptionNew) context:NULL];
@@ -839,10 +811,6 @@ default_device_changed(AudioObjectID inObjectID, UInt32 inNumberAddresses, const
 }
 
 - (void)stop {
-	if(@available(macOS 11, *)) {
-		currentWorkgroup = nil;
-	}
-
 	stopInvoked = YES;
 	if(observersapplied) {
 		observersapplied = NO;