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UE热更新：基于HotPatcher的自动化流程

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HotPatcher is an open-source version management and resource packaging tool for UE4 hot updates that I developed earlier. It allows for convenient differential analysis between versions and pak packaging. Previous articles have visually introduced this based on manual configuration and packaging within the editor. In actual engineering practice, it’s preferable to automate repetitive operations to avoid manual involvement. I added commandlet support to the plugin earlier, and recently, I have fixed some issues and added many optimizations for commandlet. This article discusses the engineering practice of the automated hot update process based on HotPatcher.

In previous articles, I introduced the working mechanism of HotPatcher. More detailed information can be found in the following articles:

The process can be simply divided into the following steps:

  1. Use UE’s method to create a base package;
  2. Extract the paklist file from the base package and import it into HotPatcher for analysis;
  3. Generate release information for the base package (one release for multiple platforms);
  4. Compare hot update versions based on release information;
  5. Generate a patch;

Thus, the aim of this article is to realize a configurable automated process for these key steps, and this process and all configuration files should not be affected by non-critical factors such as differences in engine and project paths on different machines, achieving a truly generic configuration and process.

Automating the Base Package

When integrating into CI/CD for automated packaging, you can use UE’s BuildGraph to guide UBT and UAT work.

You can directly use the following command (modify the engine, project, and platform according to your actual situation):

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E:\UnrealEngine\Launcher\UE_4.25\Engine\Build\BatchFiles\RunUAT.bat BuildCookRun -nocompileeditor -installed -nop4 -project="E:/Examples/Blank425/Blank425.uproject" -cook -stage -archive -archivedirectory="E:/Examples/Blank425/Package" -package -pak -prereqs -nodebuginfo -targetplatform=Android -cookflavor=ASTC -build -target=Blank425 -clientconfig=Development -utf8output

Supported platform names are:

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Win32,Win64,HoloLens,Mac,XboxOne,PS4,IOS,Android,HTML5,Linux,LinuxAArch64,AllDesktop,TVOS,Switch,Lumin

You can also write your own BuildGraph script to more precisely control the packaging phases for better customization—this won’t be elaborated on here, but you can search online for related articles.

Using the above command, you can package UE projects through the command line and encapsulate it within a script to integrate into the CI/CD platform.

The focus of this section is not on the packaging itself but on immediately extracting the current paklist*.txt file generated by UE during the packaging process.

When UE creates the base package, it packages the resources configured in the project into pak files. During UE’s packaging process, a paklist*.txt file is also created to record which resources need to be turned into pak files. Hence, by extracting the paklist*.txt file, you can know which files are included in the current base package (note that it’s not only uassets).

HotPatcher provides two ways to generate the Release information for the base package (which records all resource information within the base package):

  1. By importing the paklist file generated during the base package creation.
  2. By specifying the packaging directory and adding external files.

I recommend the first method as it is more precise. It can accurately analyze any file in the base package (uasset/non-uasset), and it can analyze the difference files in the base packages across different platforms, achieving complete and precise extraction of base package information.

When UE creates the base package, it defaults to storing the paklist file in the following paths (the paths are different for the source version and the installed version):

Installed Engine:

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%AppData%\Unreal Engine\AutomationTool\Logs\engine_path_combination\PakList_*.txt

Where engine_path_combination rules are:

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# Engine Path
E:\UnrealEngine\Launcher\UE_4.25
# After Combination
E+UnrealEngine+Launcher+UE_4.25

Source Engine:

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Engine\Programs\AutomationTool\Saved\Logs\BuildCookRun\PakList_*.txt

Therefore, after finishing the base packaging, extract the paklist_*.txt files according to the path rules above. For the installed version, on Windows, you can use the following file copy command:

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echo f|xcopy /y/i/s/e "%AppData%\Unreal Engine\AutomationTool\Logs\E+UnrealEngine+Launcher+UE_4.25\PakList_*.txt" "E:\ClientVersion\0.0.1.0"

This command will copy all files in the current directory that match the paklist_*.txt rule to the specified directory.

To unify the source version and installed version paklist path differences, you can write a Python script:

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def GetPakListFileRules(target_platform,engine_root_dir):
    b_installed_engine = False
    installedbuild_txt_path = "%s\\Engine\\Build\\InstalledBuild.txt" % engine_root_dir
    if os.path.exists(InstalledBuild_txt_path):
        b_installed_engine = True

    ue_paklist_dir = ""
    if b_installed_engine:
        sys_appdata_dir = os.getenv("APPDATA")
        ue_aut_log_dir = "Unreal Engine\\AutomationTool\\Logs"
        engine_log_dir = engine_root_dir
        engine_log_dir = engine_log_dir.replace(':','')
        engine_log_dir = engine_log_dir.replace('\\','+')
        engine_log_dir = engine_log_dir.replace('/','+')
        ue_paklist_dir = "%s\\%s\\%s\\BuildCookRun" % (sys_appdata_dir,ue_aut_log_dir,engine_log_dir)
    else:
        ue_paklist_dir = "%s\\Engine\\Programs\\AutomationTool\\Saved\\Logs\\BuildCookRun" % engine_root_dir
    print(ue_paklist_dir)
    ue_pak_list_rule = "%s\\PakList_pakchunk*-%s.txt" % (ue_paklist_dir,GetRealPlatformName(target_platform))
    return ue_pak_list_rule

Usage:

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ue_paklist_rules = GetPakListFileRules("Android_ASTC","C:\\Program Files\\Epic Games\\UE_4.26")

You can modify it simply according to your project needs.

Note: Every time a platform is packaged, the paklist file for that platform must be extracted immediately, as when the next packaging task is executed, files in that directory will be cleaned.

Automating the Extraction of Base Package Information

In the previous step, the automation of two key points was realized:

  1. UE packaging
  2. Extracting the current platform’s base package paklist

The focus of this section is on how to generate multi-platform release processes after we have packaged 0.0.1.0 version base packages for multiple platforms and extracted the corresponding paklist files.

The extracted directory structure of several platforms’ Paklist is as follows:

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E:\ClientVersion\0.0.1.0>tree /a /f
Volume in folder Document is
Volume serial number is 0003-AEBB
E:.
+---Android_ASTC
|       PakList_pakchunk0-Android_ASTC.txt
|       PakList_pakchunk1-Android_ASTC.txt
|       PakList_pakchunk2-Android_ASTC.txt
|
+---IOS
|       PakList_pakchunk0-ios.txt
|       PakList_pakchunk1-ios.txt
|       PakList_pakchunk2-ios.txt
|
\---WindowsNoEditor
        PakList_pakchunk0-WindowsNoEditor.txt
        PakList_pakchunk1-WindowsNoEditor.txt
        PakList_pakchunk2-WindowsNoEditor.txt

The storage structure and file names of paklists across several platforms follow the same rule, and as long as there is a rule, they can be processed automatically.

HotPatcher provides the HotRelease commandlet, which can be used in the command line to export releases, and a configuration file can be specified:

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UE4Editor.exe PROJECT.uproject -run=HotRelease -config="release-config.json"

However, simply specifying a configuration file is not very user-friendly in the command line, because it first requires constructing the config file to specify it. Recently, I have enhanced the HotRelease commandlet to allow complete control of config parameters through the command line without specifying the config file.

As mentioned earlier, HotPatcher supports two modes to export release information. Thus, when using the import paklist, you only need to specify the following key parameters:

  1. VersionId Current release version number
  2. ByPakList Enable paklist mode
  3. PlatformsPakListFiles Specify the corresponding paklist*.txt files for each platform
  4. SavePath Path to save generated release

I used UE’s reflection mechanism to allow constructing real configuration information based on names defined in the command line specified parameter structure (arrays are not yet supported), which will let you specify the parameters above when executing the commandlet.

Therefore, the command to use the HotRelease commandlet is as follows (to facilitate viewing, I’ve broken down the parameters over multiple lines):

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E:\UnrealEngine\Launcher\UE_4.25\Engine\Binaries\UE4Editor-cmd.exe
E:\Examples\Blank425\Blank425.uproject
-run=HotRelease
-versionid="0.0.1.0"
-ByPakList=true
-AddPlatformPakList=WindowsNoEditor+E:\ClientVersion\0.0.1.0\WindowsNoEditor\PakList_pakchunk0-WindowsNoEditor.txt+E:\ClientVersion\0.0.1.0\WindowsNoEditor\PakList_pakchunk1-WindowsNoEditor.txt+E:\ClientVersion\0.0.1.0\WindowsNoEditor\PakList_pakchunk2-WindowsNoEditor.txt
-savepath.path="E:\ClientVersion\"

AddPlatformPakList is used to specify Platform-PaklistFiles parameters via the command line and is required to be in the format:

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PLATFORM_NAME+Paklist_0.txt+PakList_1.txt,PLATFORM_NAME+Paklist_0.txt+PakList_1.txt

Multiple platforms can be specified, separated by commas (,), with each platform’s section starting with the platform name followed by the + sign, allowing for any quantity of paklist files to be specified.

For example, to specify WindowsNoEditor/Android_ASTC/IOS for three platforms:

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-AddPlatformPakList=WindowsNoEditor+E:\Paklist_chunk01_WindowsNoEditor.txt+E:\Paklist_chunk02_WindowsNoEditor.txt,Android_ASTC+E:\Paklist_chunk01_Android_ASTC.txt+E:\Paklist_chunk02_Android_ASTC.txt,IOS+E:\Paklist_chunk01_IOS.txt+E:\Paklist_chunk02_IOS.txt

The specified platform and file paths are both systematic, allowing you to wrap it in a script using Python to suit your project management style, and finally execute the commandlet using os.system, replicating the behavior of manually executing ByRelease in the HotPatcher editor.

Note: Although the Release.json records the absolute paths of Non-uasset files, when performing version comparisons, the absolute paths of the files are not checked. Therefore, the Release.json file is universally applicable across machines (compared using resource paths and mount paths).

Automating Patch Generation

The previous section has already introduced how to automate the generation of Release information. The configuration options required for Release are few, but Patch has considerably more configurations; thus, completely discarding the config file would complicate matters. Therefore, I considered a compromise solution—specifying a common configuration file while allowing specific parameters to be specified via the command line.

So, what are the common configuration files?

  • Resource directories to scan for Patch
  • Files to add (ini/shaderbytecode/assetregistry)
  • Non-uasset files and directories
  • Chunk partitioning

What can be specified via the command line?

  • VersionID
  • Base version release file
  • Whether to cook the resources in the current patch
  • Platforms to generate patches for
  • Naming rules for pak files
  • Save directory

In older versions of HotPatcher, configuration files relied on various parameters’ absolute paths (for added Non-uasset files). Recently, I optimized it to support relative paths concerning the project directory.

For example, to add the Content/Script directory, previously, only absolute path folder selection was allowed:

Now it can be replaced with [PROJECT_CONTENT_DIR]:

During the execution of the patch, it will scan and replace with the current project’s absolute path.

Supported relative paths with [] markers include:

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[ENGINEDIR]
[ENGINE_CONTENT_DIR]
[PROJECTDIR]
[PROJECT_CONTENT_DIR]
[PROJECT_SAVED_DIR]
[PROJECT_CONFIG_DIR]

These can be used as needed, and this approach allows for exporting a generic configuration.

PatchTemplate.json
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{
	"bByBaseVersion": true,
	"baseVersion":
	{
		"filePath": ""
	},
	"versionId": "",
	"assetIncludeFilters": [
		{
			"path": "/Game"
		}
	],
	"assetIgnoreFilters": [],
	"bForceSkipContent": true,
	"forceSkipContentRules": [
		{
			"path": "/Engine/Editor"
		},
		{
			"path": "/Engine/VREditor"
		}
	],
	"forceSkipAssets": [],
	"bIncludeHasRefAssetsOnly": false,
	"bAnalysisFilterDependencies": true,
	"bRecursiveWidgetTree": true,
	"assetRegistryDependencyTypes": [
		"Packages"
	],
	"includeSpecifyAssets": [],
	"bIncludeAssetRegistry": true,
	"bIncludeGlobalShaderCache": false,
	"bIncludeShaderBytecode": false,
	"bIncludeEngineIni": false,
	"bIncludePluginIni": false,
	"bIncludeProjectIni": false,
	"bEnableExternFilesDiff": true,
	"ignoreDeletionModulesAsset": [],
	"addExternAssetsToPlatform": [
		{
			"targetPlatform": "AllPlatforms",
			"addExternFileToPak": [],
			"addExternDirectoryToPak": [
				{
					"directoryPath":
					{
						"path": "[PROJECT_CONTENT_DIR]/Script"
					},
					"mountPoint": "../../../Blank425/Content/Script"
				}
			]
		}
	],
	"bIncludePakVersionFile": false,
	"pakVersionFileMountPoint": "../../../Blank425/Versions/version.json",
	"bEnableChunk": false,
	"chunkInfos": [],
	"bCookPatchAssets": true,
	"pakCommandOptions": [],
	"replacePakCommandTexts": [],
	"unrealPakOptions": [
		"-compress",
		"-compressionformats=Zlib"
	],
	"pakTargetPlatforms": [],
	"bCustomPakNameRegular": false,
	"pakNameRegular": "{VERSION}_{CHUNKNAME}_{PLATFORM}_001_P",
	"bIgnoreDeleatedAssetsInfo": false,
	"bSaveDeletedAssetsToNewReleaseJson": true,
	"bSavePakList": true,
	"bSaveDiffAnalysis": true,
	"bSaveAssetRelatedInfo": false,
	"bSavePatchConfig": true,
	"savePath":
	{
		"path": ""
	}
}

This configuration can serve as a generic configuration file related to resources for generating patches; when we wish to modify packaging configurations, we only need to update this file.

All other version-related parameters can be specified through the HotPatcher commandlet command line:

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E:\UnrealEngine\Launcher\UE_4.25\Engine\Binaries\UE4Editor-cmd.exe
E:\Examples\Blank425\Blank425.uproject
-run=HotPatcher
-config="E:\ClientVersion\PatchTemplate.json"
-versionid="0.0.1.1"
-baseVersion.filePath="E:\ClientVersion\0.0.1.0\0.0.1.0_Release.json"
-AddPatchPlatforms="WindowsNoEditor,Android_ASTC,IOS"
-savePath.path="E:\ClientVersion\"

This command’s parameters also follow certain rules. When the directory structure is well-organized, by simply specifying the current patch’s base version and current version number, the packaging can be fully automated.

Likewise, the patch generation process can be encapsulated using scripts like Python, allowing CI/CD platforms to specify engine directory, project directory, baseline version, current version, and which platforms to generate patches for, facilitating control.

Conclusion

This article introduces the automation of hot update processes using HotPatcher, including UE’s automatic generation of base packages, extraction of paklists, release generation, and generic patch generation rules, allowing for easy integration into CI/CD platforms to avoid manual involvement.

In the future, I will write a Python script for automating the export of Release/Patch from HotPatcher for easy use.

The article is finished. If you have any questions, please comment and communicate.

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Title:UE热更新：基于HotPatcher的自动化流程
Author:LIPENGZHA
Publish Date:2021/01/24 12:47
World Count:8.4k Words
Link:https://en.imzlp.com/posts/10938/
License: CC BY-NC-SA 4.0
Reprinting of the full article is prohibited.
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