PHP 中的 stream_select()、信号和标准输入

Question

I am trying to write a native PHP CLI application which reads data (log data) from stdin and does some handling after.

I got a first working version with a simple while-Loop:

while ($line = fgets(STDIN)) {
    // Do my stuff here
}

When installing signal handling via

function signal_handler(int $signo, mixed $siginfo) {
    // ...
}

pcntl_async_signals(TRUE);
pcntl_signal(SIGHUP, 'signal_handler');

this works partly: The signals are only processed after each fgets() .

I tried to use stream_select() with NULL as timeout and some other stuff, but this lead to a massive system load:-)

Is there any best practice to use stream_select() and fgets() on stdin to read data until it's "ready" and wait/pause indefinitely else but let signals being processed?

Answer 1

You can use stream_set_blocking(STDIN, 0); to remove the blocking.

Example:

function signal_handler(int $signo,  $siginfo) {
    exit("signal caught\n");
}

stream_set_blocking(STDIN, 0);
pcntl_async_signals(TRUE);
pcntl_signal(SIGHUP, 'signal_handler');

echo "pid=" . posix_getpid() . "\n";

echo "Listening input...\n";
while (true) {
    while ($line = fgets(STDIN)) {
        echo "Input: '$line'\n";
    }
}

Possible output:

Pid=46834
Listening input...
Input: 'test'
signal caught

See stream_set_blocking()