cfexample.cpp

// This is a snippet from https://github.com/SeijiEmery/GLSandbox/blob/master/fsevents-test/main.cpp

void fsEventCallback (
    ConstFSEventStreamRef streamRef,
    void *clientCallBackInfo,
    size_t numEvents,
    void *eventPaths,
    const FSEventStreamEventFlags eventFlags[],
    const FSEventStreamEventId eventIds[]
) {
    char **paths = (char **)eventPaths;
    for (auto i = 0; i < numEvents; ++i) {
        printf("Change %llu in %s, flags %d\n", eventIds[i], paths[i], eventFlags[i]);
        
        // GlobalFileChangeWatcher is a c++ class that does further processing (recursively scans local files, etc)
        // This code just uses osx services to determine when _something_ changed (ie. a directory path), and determine
        // _what_ changed and how to handle that (file type, extensions, are we using it, etc) is done by GFCW and uses
        // recursive stat calls.
        GlobalFileChangeWatcher::getInstance().update_dir(paths[i]);
    }
}

struct FSDirWatcher {
    CFStringRef dir_path;
    FSEventStreamRef stream;
    CFAbsoluteTime latency = 3.0;
    
    FSDirWatcher (const char * path) {
        printf("setup event stream listener on '%s'\n", path);
        GlobalFileChangeWatcher::getInstance().add_dir(path);
        
        dir_path = CFStringCreateWithCString(kCFAllocatorDefault, path, kCFStringEncodingUTF8);
        CFArrayRef pathsToWatch = CFArrayCreate(kCFAllocatorDefault, (const void**)&dir_path, 1, nullptr);
        
        stream = FSEventStreamCreate(kCFAllocatorDefault,
                (FSEventStreamCallback)&fsEventCallback,
                nullptr,
                pathsToWatch,
                kFSEventStreamEventIdSinceNow,
                latency,
                kFSEventStreamCreateFlagNone);
        CFRelease(pathsToWatch);
        
        FSEventStreamScheduleWithRunLoop(stream, CFRunLoopGetCurrent(), kCFRunLoopDefaultMode);
        FSEventStreamStart(stream);
    }
    ~FSDirWatcher () {
        FSEventStreamStop(stream);
        CFRelease(dir_path);
    }
};
typedef std::shared_ptr<FSDirWatcher> FSDirWatcherRef;

int main(int argc, const char * argv[]) {
    CFRunLoopGetCurrent();
    
    std::vector<FSDirWatcherRef> watchers {
        std::make_shared<FSDirWatcher> ( "/Users/semery/misc-projects/GLSandbox/" ),
        std::make_shared<FSDirWatcher> ( "/Users/semery/Library/Application Support/GLSandbox/" )
    };
    
    CFRunLoopRun();
    return 0;
}