第32月第30天 runloop阻塞线程 超时 cmake

1. runloop阻塞线程 超时

bool CvCaptureCAM::grabFrame(double timeOut) {

    NSAutoreleasePool* localpool = [[NSAutoreleasePool alloc] init];
    double sleepTime = 0.005;
    double total = 0;

    // If the capture is launched in a separate thread, then
    // [NSRunLoop currentRunLoop] is not the same as in the main thread, and has no timer.
    //see https://developer.apple.com/library/mac/#documentation/Cocoa/Reference/Foundation/Classes/nsrunloop_Class/Reference/Reference.html
    // "If no input sources or timers are attached to the run loop, this
    // method exits immediately"
    // using usleep() is not a good alternative, because it may block the GUI.
    // Create a dummy timer so that runUntilDate does not exit immediately:
    [NSTimer scheduledTimerWithTimeInterval:100 target:nil selector:@selector(doFireTimer:) userInfo:nil repeats:YES];
    while (![capture updateImage] && (total += sleepTime)<=timeOut) {
        [[NSRunLoop currentRunLoop] runUntilDate:[NSDate dateWithTimeIntervalSinceNow:sleepTime]];
    }

    [localpool drain];

    return total <= timeOut;
}

 2.cmake

、cmake编译

cd opencv-3.4.1
mkdir build
cd build

# 注意，下面是一条指令，部分环境下可能显示成两行，看起来像两行
cmake -D CMAKE_BUILD_TYPE=RELEASE -D CMAKE_INSTALL_PREFIX=/home/pascal/software/opencv341 ..

得到结果

-- Configuring done
-- Generating done
-- Build files have been written to: /home/pascal/downloads/opencv-3.4.1/build

4、make编译

make