Re: dispatch_source does not work
Re: dispatch_source does not work
- Subject: Re: dispatch_source does not work
- From: "Gerriet M. Denkmann" <email@hidden>
- Date: Wed, 05 Nov 2014 16:28:20 +0700
> On 5 Nov 2014, at 14:08, Peter <email@hidden> wrote:
>
> http://stackoverflow.com/questions/12343833/cocoa-monitor-a-file-for-modifications/26304208#26304208
>
> has some info on this.
Thanks a lot. Got it working now.
Mit freundlichen Grüßen
Gerriet.
>
> ___ Peter Hartmann ________
>
> mailto:email@hidden
>
>
> Am 05.11.2014 um 07:50 schrieb Gerriet M. Denkmann <email@hidden>:
>
>> I want to monitor a file for changed content.
>> Polling is generally not a good idea, so I tried dispatch_source.
>>
>> But it does not work.
>>
>> Here the code:
>>
>> static NSString *const kTestPath = @"/tmp/a.test";
>>
>> - (void)applicationDidFinishLaunching:(NSNotification *)aNotification
>> {
>> const char *filename = kTestPath.fileSystemRepresentation;
>> int fd = open(filename, O_RDONLY);
>> fcntl(fd, F_SETFL, O_NONBLOCK);
>> uintptr_t fD = (uintptr_t)fd;
>> dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
>> const uint64_t flags = DISPATCH_VNODE_WRITE | DISPATCH_VNODE_LINK;
>> dispatch_source_t my_source = dispatch_source_create(DISPATCH_SOURCE_TYPE_VNODE, fD, flags, queue);
>> dispatch_source_set_event_handler(my_source, ^{ [self fileDidChange]; } );
>> dispatch_resume(my_source);
>> }
>>
>> - (void)fileDidChange
>> {
>> NSLog(@"%s",__FUNCTION__); // never seen
>> }
>>
>> - (IBAction)buttonClicked: sender
>> {
>> static NSUInteger seqq = 0;
>> seqq++;
>>
>> const char *stats_temp_file = "/tmp/a.temp";
>> FILE *fp = fopen(stats_temp_file, "w");
>> fprintf(fp, "%lu\n", seqq);
>> (void)fclose(fp);
>>
>> const char *filename = kTestPath.fileSystemRepresentation;
>> int a = rename(stats_temp_file, filename);
>> }
>>
>> What am I doing wrong? (Writing directly to kTestPath without rename() also does not work).
>>
>> Gerriet.
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