Objective-C: AtomicQueue

atomic_queue.m

#import <Foundation/Foundation.h>

@interface AtomicQueue : NSObject
- (id)init;
- (id)dequeue;
- (void)enqueue:(id)data;
@end

@implementation AtomicQueue {
    NSMutableArray *queue;
    id lock;
}

- (id)init {
    queue = [NSMutableArray new];

    return self;
}

- (id)dequeue {
    id data = nil;
    @synchronized (lock) {
        if ([queue count] > 0) {
            data = [queue objectAtIndex:0];
            [queue removeObjectAtIndex:0];
        }
    }
    return data;
}

- (void)enqueue:(id)data {
    @synchronized (lock) {
        [queue addObject:data];
    }
}

@end

int main() {
    AtomicQueue *queue = [AtomicQueue new];

    [queue enqueue:(id)5];
    [queue :(id)7];

    NSInteger j = (NSInteger)[queue dequeue];
    NSLog(@"%lu", j);

    [queue enqueue:(id)9];

    [queue dequeue];

    j = (NSInteger)[queue dequeue];
    NSLog(@"%lu", j);

    j = (NSInteger)[queue dequeue];
    NSLog(@"%lu", j);

    j = (NSInteger)[queue dequeue];
    NSLog(@"%lu", j);

    return 0;
}