PostgreSQL source code learning (26) -- windows vscode remote debugging PostgreSQL on Linux

This article commemorates Xiaobai's success in debugging the source code with development tools for the first time ~

       gdb There are still many inconveniences in using command line debugging , Originally, I wanted to find a simple way to debug directly Windows Under the pg Source code , I've been looking for it for a long time vs, Too heavy and complicated . Most actual environments still run in Linux Of , So it's better to debug Linux Under the pg Source code .

• Target end ：centos 7+postgresql 14
• Source end ：Windows 10 + vscode

 

One 、 postgresql 14 Source code compilation and installation

•       Before written pg Source code installation method for debugging , It's the same here （ So if you have installed it before, you can use this environment ）. Special attention should be paid to adding --enable-debug, Otherwise, it is impossible to debug .

postgresql Source code learning （ One ）—— Source code compilation and installation gdb Introduction to debugging _Hehuyi_In The blog of -CSDN Blog _postgresql The source code to debug

        Try the inside after installation gdb Examples of debugging , Because the later tools will also rely on gdb. If the execution is OK , Then we can go on .

Two 、 install vscode

Download link ：Visual Studio Code - Code Editing. Redefined

If it's too slow , There are also a large number of websites in China that provide downloads , The next step in the installation process is the next step .

1. Local installation vscode plug-in unit

Under it 3 individual ：

• C/C++
• C/C++ Runner： compile 、 function 、debug
• Remote Development： Remote development . It has three plug-ins installed ：Remote-SSH,Remote-Container,Remote-WSL, If you only need ssh Connect , Only install Remote-SSH Can .

2. Test remote connection

        stay Remote Development After the plug-in is installed , There will be a small computer icon in the lower left corner , Click it , Then build ssh Connect . Fill in the box as prompted  ssh [email protected]

Click the small plus sign next to it after matching , A new interface will pop up to let you enter the password

The first time you go in, it will install vscode, It will be slow , It's in /root Now create a hidden Directory vscode.

If an error is reported during installation Resolver error: Error: XHR failed, It could be a network problem , hold linux Upper .vscode Delete the table of contents , Just try again a few times .

    After the connection is successful, you can see Linux The command line

3、 ... and 、 Configure remote debugging pg

Open source src Catalog , establish .vscode Catalog , as well as launch.json file . Direct use Linux The command line can also , adopt vscode It's OK to build

launch.json The contents of the document are as follows

{
    "version": "0.2.0",
    "configurations": [
        {
            "name": "postgresql",
            "type": "cppdbg",
            "request": "attach",
            "program": "/data/postgres/base/14.4/bin/postgres",
            "processId": "${command:pickProcess}",
            "MIMode": "gdb",
            "setupCommands": [
                {
                    "description": "Enable pretty-printing for gdb",
                    "text": "-enable-pretty-printing",
                    "ignoreFailures": true
                },
                {
                    "description":  "Set Disassembly Flavor to Intel",
                    "text": "-gdb-set disassembly-flavor intel",
                    "ignoreFailures": true
                }
          ]
        }
    ]
}

The only thing to change is "program": "/data/postgres/base/14.4/bin/postgres", Change to the actual path .

in addition Distal vscode Need to install json plug-in unit , Otherwise, an error will be reported and the file cannot be parsed .

By the way, I looked at the plug-ins installed on the remote end , except json and C/C++ Extension Pack, Others seem to be installed automatically .

If you encounter this error , Say you can't recognize cppdbg, It's not installed C/C++ Runner plug-in unit , Just install it .

Four 、 Remote debugging test

We use the simplest begin Operation as an example , track StartTransactionCommand Function execution . This function is in the /root/postgresql-14.4/src/backend/access/transam/xact.c In file

vscode End ：

find xact.c In the document StartTransactionCommand function , Set a breakpoint

linux End ：

psql Create connection , Query process number

select pg_backend_pid();

vscode End ：

Start debug, Shortcut key F5

attach Corresponding process

You will see this output in the lower right corner

linux End ：

Execute one begin command , It will get stuck

vscode End ：

The cursor jumps to the corresponding function , It indicates that debugging has started , You can click the small arrow above , Step by step .

The main areas of the debugging interface are as follows ：

• variable： The variable value corresponding to the execution of each step , This is very useful
• call stack： The call stack , Look from the bottom up
• The line that lights up in the code is the currently executed line

Through the comparison of code and variable value , It's easy to see what to do next case, And then do something .

thus , Our debugging test is successful , Stepped out pg The first step in learning the source code of the long march ~

Reference resources

https://blog.csdn.net/loveoobaby/article/details/123765071?spm=1001.2014.3001.5501

https://blog.csdn.net/loveoobaby/article/details/123766468

https://blog.csdn.net/Hehuyi_In/article/details/110729822

https://blog.csdn.net/Hehuyi_In/article/details/124524307

https://blog.csdn.net/wangyjfrecky/article/details/124681577

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