obs-studio/plugins/mac-virtualcam/src/obs-plugin/OBSDALMachServer.mm

//
//  MachServer.m
//  mac-virtualcam
//
//  Created by John Boiles  on 5/5/20.
//

#import "OBSDALMachServer.h"
#include <obs-module.h>
#include "MachProtocol.h"
#include "Defines.h"

@interface OBSDALMachServer () <NSPortDelegate>
@property NSPort *port;
@property NSMutableSet *clientPorts;
@property NSRunLoop *runLoop;
@end

@implementation OBSDALMachServer

- (id)init
{
    if (self = [super init]) {
        self.clientPorts = [[NSMutableSet alloc] init];
    }
    return self;
}

- (void)dealloc
{
    blog(LOG_DEBUG, "tearing down MachServer");
    [self.runLoop removePort:self.port forMode:NSDefaultRunLoopMode];
    [self.port invalidate];
    self.port.delegate = nil;
}

- (void)run
{
    if (self.port != nil) {
        blog(LOG_DEBUG, "mach server already running!");
        return;
    }

// It's a bummer this is deprecated. The replacement, NSXPCConnection, seems to require
// an assistant process that lives inside the .app bundle. This would be more modern, but adds
// complexity and I think makes it impossible to just run the `obs` binary from the commandline.
// So let's stick with NSMachBootstrapServer at least until it fully goes away.
// At that point we can decide between NSXPCConnection and using the CoreFoundation versions of
// these APIs (which are, interestingly, not deprecated)
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wdeprecated-declarations"
    self.port = [[NSMachBootstrapServer sharedInstance] servicePortWithName:@MACH_SERVICE_NAME];
#pragma clang diagnostic pop
    if (self.port == nil) {
        // This probably means another instance is running.
        blog(LOG_ERROR, "Unable to open mach server port.");
        return;
    }

    self.port.delegate = self;

    self.runLoop = [NSRunLoop currentRunLoop];
    [self.runLoop addPort:self.port forMode:NSDefaultRunLoopMode];

    blog(LOG_DEBUG, "mach server running!");
}

- (void)handlePortMessage:(NSPortMessage *)message
{
    switch (message.msgid) {
        case MachMsgIdConnect:
            if (message.sendPort != nil) {
                blog(LOG_DEBUG, "mach server received connect message from port %d!",
                     ((NSMachPort *) message.sendPort).machPort);
                [self.clientPorts addObject:message.sendPort];
            }
            break;
        default:
            blog(LOG_ERROR, "Unexpected mach message ID %u", (unsigned) message.msgid);
            break;
    }
}

- (void)sendMessageToClientsWithMsgId:(uint32_t)msgId components:(nullable NSArray *)components
{
    if ([self.clientPorts count] <= 0) {
        return;
    }

    NSMutableSet *removedPorts = [NSMutableSet set];

    for (NSPort *port in self.clientPorts) {
        @try {
            NSPortMessage *message = [[NSPortMessage alloc] initWithSendPort:port receivePort:nil
                                                                  components:components];
            message.msgid = msgId;
            if (![port isValid] || ![message sendBeforeDate:[NSDate dateWithTimeIntervalSinceNow:1.0]]) {
                blog(LOG_DEBUG, "failed to send message to %d, removing it from the clients!",
                     ((NSMachPort *) port).machPort);

                [port invalidate];
                [removedPorts addObject:port];
            }
        } @catch (NSException *exception) {
            blog(LOG_DEBUG, "failed to send message (exception) to %d, removing it from the clients!",
                 ((NSMachPort *) port).machPort);

            [port invalidate];
            [removedPorts addObject:port];
        }
    }

    // Remove dead ports if necessary
    [self.clientPorts minusSet:removedPorts];
}

- (void)sendPixelBuffer:(CVPixelBufferRef)frame
              timestamp:(uint64_t)timestamp
           fpsNumerator:(uint32_t)fpsNumerator
         fpsDenominator:(uint32_t)fpsDenominator
{
    if ([self.clientPorts count] <= 0) {
        return;
    }

    @autoreleasepool {
        NSData *timestampData = [NSData dataWithBytes:&timestamp length:sizeof(timestamp)];
        NSData *fpsNumeratorData = [NSData dataWithBytes:&fpsNumerator length:sizeof(fpsNumerator)];
        NSData *fpsDenominatorData = [NSData dataWithBytes:&fpsDenominator length:sizeof(fpsDenominator)];

        IOSurfaceRef surface = CVPixelBufferGetIOSurface(frame);
#ifndef __aarch64__
        IOSurfaceLock(surface, 0, NULL);
#endif

        if (!surface) {
            blog(LOG_ERROR, "unable to access IOSurface associated with CVPixelBuffer");
            return;
        }

        mach_port_t framePort = IOSurfaceCreateMachPort(surface);

        if (!framePort) {
            blog(LOG_ERROR, "unable to allocate mach port for IOSurface");
            return;
        }

        [self sendMessageToClientsWithMsgId:MachMsgIdFrame components:@[
            [NSMachPort portWithMachPort:framePort options:NSMachPortDeallocateNone], timestampData, fpsNumeratorData,
            fpsDenominatorData
        ]];

        mach_port_deallocate(mach_task_self(), framePort);

#ifndef __aarch64__
        IOSurfaceUnlock(surface, 0, NULL);
#endif
    }
}

- (void)stop
{
    blog(LOG_DEBUG, "sending stop message to %lu clients", self.clientPorts.count);
    [self sendMessageToClientsWithMsgId:MachMsgIdStop components:nil];
}

@end