小编Dau*_*kas的帖子

我正在尝试创建一个视频库.

要显示我正在使用的视频UICollectionView.每个UICollectionViewCell都有一个背景与视频缩略图.要生成视频缩略图,我使用的是逻辑方法:

AVURLAsset *asset = [[AVURLAsset alloc] initWithURL:url options:nil];

AVAssetImageGenerator *generator = [[AVAssetImageGenerator alloc] initWithAsset:asset];

generator.appliesPreferredTrackTransform = YES;

CMTime time = CMTimeMakeWithSeconds(0,15);

AVAssetImageGeneratorCompletionHandler handler = ^(CMTime timeRequested, CGImageRef image, CMTime timeActual, AVAssetImageGeneratorResult result, NSError *error)
{
    NSLog(@"handler^()");

    if (result == AVAssetImageGeneratorSucceeded)
    {
        thumbnail = [UIImage imageWithCGImage: image];

        success(thumbnail);
    }

    else
    {
        failure(error);
    }
};

CGSize maximumSize = CGSizeMake(CLIPBOARD_COLLECTION_VIEW_CELL_WIDTH, CLIPBOARD_COLLECTION_VIEW_CELL_HEIGHT);

generator.maximumSize = maximumSize;

NSLog(@"generateCGImagesAsynchronouslyForTimes:");
[generator generateCGImagesAsynchronouslyForTimes:[NSArray arrayWithObject:[NSValue valueWithCMTime:time]] completionHandler:handler];

我注意到generateCGImagesAsynchronouslyForTimes它不能完全异步工作.此方法调用之间有一个时间空间.当我加载表格视图单元格时,这会导致很大的延迟.如果我评论行[generator generateCGImagesAsynchronouslyForTimes:[NSArray arrayWithObject:[NSValue valueWithCMTime:time]] completionHandler:handler] …

我试图通过访问ETS模块创建一个简单的Erlang进程.

我的源代码包括:

1. 流程创建:

   start_message_channel() ->
       Table = ets:new(messages, [ordered_set, named_table]),
       Channel = spawn(?MODULE, channel, []),
       {Channel, {table, Table}}.
   

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2. 流程逻辑:

   channel() ->
       receive
           {Sender, {send_message, {Message, Table}}} ->
               ets:insert(Table, {message, Message}),
               Sender ! {self(), {status, success}};
           {Sender, {receive_message, Table}} ->
               {message, Message} = ets:first(Table),
               Sender ! {self(), {status, {success, Message}}};
           _ ->
               throw(incorrect_protocol_exception)
   end.
   

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3. 与流程沟通

   send_message_to_message_channel({Channel, {table, Table}}, Message) ->
       Channel ! {self(), {send_message, {Message, Table}}},
       receive
           {Channel, {status, success}} ->
               io:format("Message sent!~n");
           {Channel, {status, failure}} ->
               io:format("Message failed to send!~n"); …

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