Source code analysis and debugging technology in PHP

PHP is a very popular server-side scripting language. Whether it is a large enterprise application or a small website, PHP can be used to complete development. However, in actual development, we will inevitably encounter various problems, such as server performance degradation, slow page access, and even bugs that are difficult to locate. At this time, source code analysis and debugging technology become very important. This article will give you a detailed introduction to source code analysis and debugging technology in PHP.

1. Source code view

In PHP, the source code is divided into two parts: the Zend engine part and the PHP language part. Zend engine is the core part of PHP, which implements the parsing, compilation and execution of PHP code. The PHP language part is the specific business logic code written by developers.

To view the Zend engine source code, you can use the following methods:

1. Download the source code from the official website

The PHP official website provides source code downloads for various versions, we can directly Download the latest or specified version of the source code from the official website. The download address is: http://www.php.net/downloads.php

2. Read the online documentation

PHP officially provides a complete Zend engine documentation, which can be viewed through the following link : https://www.php.net/manual/en/internals2.php

3. Use Zend Studio

Zend Studio is an IDE specially used for PHP development, which can be directly View PHP source code. Zend Studio makes it easy to view the inner workings of PHP and debug it.

2. Debugging Tools

PHP provides a variety of debugging tools, including Zend Debugger, XDebug, DBG, etc. We can choose the appropriate debugging tool based on the actual situation.

1.Zend Debugger

Zend Debugger is a debugging tool developed by Zend Technologies and has been integrated into Zend Studio. Local and remote debugging can be easily performed, and PHP4 and PHP5 are supported. To use Zend Debugger, you need to enable the extension in the PHP configuration file and add the following configuration:

zend_extension=/path/to/ZendDebugger.so
zend_debugger.allow_hosts=127.0.0.1/32,zend_debugger.expose_remotely=always

After enabling, you need to configure the connection in Zend Studio. After the configuration is completed, you can start debugging.

2.XDebug

XDebug can provide performance analysis, tracking and debugging functions for PHP. It can generate code coverage reports and view function calls, variable contents, etc. Unlike Zend Debugger, the following configuration needs to be added to the PHP configuration file to activate the XDebug extension:

zend_extension = /path/to/xdebug.so
xdebug.remote_enable = 1
xdebug.remote_handler = dbgp
xdebug.remote_host = "localhost"
xdebug.remote_port = 9000

Modify the above configuration according to the actual situation. After the configuration is completed, you need to connect in the debugging tool. After the connection is successful, you can proceed with the code Analysis and debugging.

3.DBG

DBG is a debugging tool developed based on Zend technology and can be used in IDEs such as Zend Studio, Eclipse, and Vim. Compared with the above two debugging tools, DBG is slightly more complicated to use, but it can achieve more personalized debugging needs.

After installing DBG, you need to add the following configuration to the PHP configuration file:

extension=php_dbg.dll # Windows
extension=php_dbg.so # Linux
[debugger]
debugger.enabled=on
debugger.profiler_enabled=off
debugger.hosts_allow=127.0.0.1
debugger.hosts_deny=all
debugger.ports=7869

After enabled By configuring information such as the connection port and IP in the IDE, DBG-based source code analysis and debugging can be achieved.

3. Debugging skills

1. Use echo, print or var_dump to print content

This is the most commonly used debugging method. You can know what the current program is by printing the output. The location and status of variables can help us quickly implement source code analysis and debugging.

2. Use XDebug to generate a code coverage report

XDebug can generate a code coverage report for us, and you can see which parts of the program have been executed and which parts have not been executed. During the debugging process, you can use the generated report to judge the current program execution status and quickly locate problems.

3. Use Zend Debugger to implement remote debugging

Zend Debugger can implement remote debugging and is suitable for debugging operations in test environments and production environments. Through the remote debugging function, you can quickly locate the error location and solve the problem.

4. Use breakpoints

Set breakpoints in the program to pause the execution of the program when it reaches the breakpoint. This way you can step through a program, inspect the values ​​of variables, and watch the program run.

Summary

PHP source code analysis and debugging technology is one of the necessary skills for developers. This article introduces source code viewing and common debugging tools in PHP, as well as some common debugging techniques. In actual development, we should choose appropriate tools and technologies for source code analysis and debugging to improve development efficiency and accuracy.

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