PHP using flock to implement file Lock method _php Tutorial

PHP uses flock to implement file lock method

The example in this paper describes how PHP uses flock to implement file locking. Share to everyone for your reference. The specific analysis is as follows:

Flock's explanation in the official documentation is that flock () allows you to perform a simple read/write model that can be used on any platform (including most Unix-derived versions and even Windows). If the lock is blocked (ewouldblock error code case), set the optional third parameter to TRUE. The lock operation can also be released by Fclose (), which is also automatically called when the code is finished executing.

In simple terms, locking a file allows multiple processes to restrict access to the file, preventing collisions. As an example:

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$file = fopen ("Test.txt", "w+"); if (Flock ($file, LOCK_EX)) { Fwrite ($file, "Write something"); Flock ($file, lock_un); } Else { echo "Error locking file!"; } Fclose ($file); ?>

Description

1. This code means to open the file Test.txt read-write, when a user calls the PHP page, that is, the Test.txt file operation, then the Flock ($file, LOCK_EX) code is executed, the Test.txt file will be exclusive lock ( The file can only be read and written by that user, and if any other new user wants to access the file, it will be blocked until the file is closed (releasing the lock).

2. If the code is changed to flock ($file, LOCK_EX+LOCK_NB) to indicate that the error is returned directly when locked, then the "Error locking file!" will be output if a new user accesses the file

3. The syntax of the function is flock (file,lock,block), where file is required. Specifies the open files to lock or release. Lock required. Specifies which type of lock to use. Block is optional. If set to 1 or true, the other process is blocked when the lock is made.

For example: Write a PHP code to ensure that multiple processes write to the same file successfully

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function WriteData ($path, $mode, $data) { $fp = fopen ($path, $mode); $retries = 0; $max _retries = 100; do{ if ($retries > 0) { Usleep (rand (1, 10000)); } $retries + = 1; }while (!flock ($FP, LOCK_EX) and $retries <= $max _retries); if ($retries = = $max _retries) { return false; } Fwrite ($fp, "$data \ n"); Flock ($FP, lock_un); Fclose ($FP); return true; }

I hope this article is helpful to everyone's PHP programming.

http://www.bkjia.com/PHPjc/1025313.html www.bkjia.com true http://www.bkjia.com/PHPjc/1025313.html techarticle PHP using flock to implement file lock method in this paper, we describe the way PHP uses flock to implement file lock. Share to everyone for your reference. The specific analysis is as follows: Flock in official documents ...

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