File operations in PHP8.0: file monitoring

With the continuous development of Web applications, PHP has become one of the most important programming languages ​​​​in Web development. As an extremely flexible programming language, each version of PHP brings new features and optimizations to meet different needs and application scenarios.

In PHP 8.0 version, a very practical file operation function has been added, namely file monitoring. This function is very suitable for application scenarios that require monitoring and processing of file changes, such as file backup, file synchronization, log monitoring, etc.

This article will give you an in-depth understanding of the file monitoring function in PHP 8.0 and how to apply it in actual projects.

1. Basic usage of PHP file monitoring

In PHP 8.0, file monitoring can be achieved by using the SplFileInfo class and SplFileObject class in the spl extension library.

1. Use the SplFileInfo class for file monitoring

$file = new SplFileInfo('/path/to/file');
while (true) {
    clearstatcache();
    if ($file->getSize() != $size) {
        // 文件大小已经改变，进行处理
    }
    sleep(1);
}

In the above example code, we use the SplFileInfo class to instantiate a file and monitor the file through a while loop. The advantage of using the SplFileInfo class is that it provides a large number of methods to obtain various information about the file, such as file size, file modification time, file type, etc. When the file content or size changes, we can perform corresponding operations.

2. Use the SplFileObject class for file monitoring

In addition to using the SplFileInfo class, we can also use the SplFileObject class to directly read and write files and monitor file changes. The following is a sample code:

$file = new SplFileObject('/path/to/file', 'r');
while (true) {
    clearstatcache();
    if ($file->getSize() != $size) {
        // 文件大小已经改变，进行处理
    }
    sleep(1);
}

In the above sample code, we created a SplFileObject instance and monitored file changes through a while loop. Different from the SplFileInfo class, we use the 'r' mode to read the file, so that the file can be read and manipulated in real time.

Another benefit of using the SplFileObject class is that you can lock the file by using the flock() function, thereby avoiding the problem of multiple processes operating on the same file at the same time.

2. Advanced usage of PHP file monitoring

In addition to the basic usage, file monitoring in PHP 8.0 version also provides some advanced usage.

1. Use the inotify extension library for file monitoring

In the Linux system, you can use the inotify extension library for file monitoring. In PHP 8.0, the inotify extension library has been built-in by default, so we can directly use the functions in this extension library for file monitoring.

Call the inotify_init() function to create an inotify object:

$inotify = inotify_init();

Then use the inotify_add_watch() function to add monitoring to the file:

$watch_descriptor = inotify_add_watch($inotify, '/path/to/file', IN_MODIFY);

In the above code, we Use the inotify_add_watch() function to add monitoring of the IN_MODIFY event to the file. This event is triggered when a file is modified.

Finally use the stream_select() function to wait for events to occur:

$read = array($inotify);
$write = $except = null;
stream_select($read, $write, $except, null);

In the above example code, we use the stream_select() function to wait for events on the inotify object. When the file is modified, it will Triggers the IN_MODIFY event.

2. Use ReactPHP for file monitoring

ReactPHP is a PHP framework based on an event-driven model, which can be used to build high-performance and highly scalable Web applications. In the ReactPHP framework, file monitoring is one of the very important functions. We can implement file monitoring by using the file monitoring component of ReactPHP.

First install the ReactPHP component:

composer require react/event-loop react/stream
composer require react/filesystem:^0.1.0

Then use the Monitor component for file monitoring:

$loop = ReactEventLoopFactory::create();
$monitor = new Monitor('/path/to/file', $loop);

$monitor->on(Monitor::EVENT_MODIFIED, function () {
    // 文件内容已经改变，进行处理
});

$loop->run();

In the above example code, we use the Monitor component of ReactPHP to monitor files monitor. When the file content is modified, the EVENT_MODIFIED event will be triggered, and then we can handle it accordingly.

3. Precautions for file monitoring

When using the file monitoring function, there are some things that need to be paid attention to:

1. Clear cache

In When performing file monitoring, you need to use the clearstatcache() function to clear the file cache. Otherwise, the program may not be able to correctly identify file changes.

2. Set the waiting time reasonably

When using a while loop to wait for file changes, you need to set the waiting time reasonably. If the waiting time is too short, system resources will be wasted; if the waiting time is too long, file changes will not be detected in time.

3. File locking

If multiple processes operate on the same file at the same time, it will cause file conflicts or overwriting. Therefore, when performing file operations, you need to use the flock() function to lock the file to avoid this problem.

4. Summary

File monitoring is a very practical function, especially in Web applications. It can be used to monitor file changes in real time and perform corresponding processing in a timely manner. In PHP 8.0, we can use SplFileInfo class, SplFileObject class, inotify extension library, ReactPHP and other tools to implement file monitoring. When using the file monitoring function, you need to pay attention to issues such as clearing the cache, setting reasonable waiting times, and file locking.

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