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Standard log output overview
Command line arguments for logging

Configure a logging plug-in

Embedded platforms might have limitations on storing the log output to a file. As a result, these platforms collect log events in special logging environments, such as DLT and slogger2. To implement this functionality in Unity, you can create a logging plug-in using the API provided in a header file located at <UnityInstallPath>/Editor/Data/PlaybackEngines/<EmbeddedLinux|QNX>/PluginAPI/unity_logging_plugin.h.

#pragma once

#include <stdint.h>

#if __GNUC__
    #define UNITY_LOGGING_PLUGIN_API extern "C" __attribute__ ((visibility ("default")))
#else
    #error "Unsupported compiler/platform"
#endif

/// Increments on changes to the UnityLoggingPluginAPI structure
#define UNITY_LOGGING_PLUGIN_VERSION 1

enum UnityLoggingLevel
{
    kUnityLoggingLevelError = 0,
    kUnityLoggingLevelAssert = 1,
    kUnityLoggingLevelWarning = 2,
    kUnityLoggingLevelLog = 3,
    kUnityLoggingLevelException = 4,
    kUnityLoggingLevelDebug = 5,
    kUnityLoggingLevelNumLevels
};

enum UnityLoggingStatus
{
    kUnityLoggingStatusSuccess = 0,
    kUnityLoggingStatusUnsupportedVersion = 1,
    kUnityLoggingStatusLoadFailure = 2,
    kUnityLoggingStatusUnloadFailure = 3,
    kUnityLoggingStatusDependencyFailure = 4,
};

typedef struct {
    const char* (*const GetString)(const char* key, const char* defaultValue);
    uint64_t (*const GetUInt64)(const char* key, uint64_t defaultValue);
    int64_t (*const GetInt64)(const char* key, int64_t defaultValue);
    uint32_t (*const GetUInt32)(const char* key, uint32_t defaultValue);
    int32_t (*const GetInt32)(const char* key, int32_t defaultValue);
} UnityLoggingPluginConfig;

typedef struct {
    typedef UnityLoggingStatus (*UnityLoggingLoad)(UnityLoggingPluginConfig* config);
    typedef UnityLoggingStatus (*UnityLoggingUnload)();
    typedef void (*UnityLoggingLog)(UnityLoggingLevel, const char*, uint32_t);

    UnityLoggingLoad Load;
    UnityLoggingUnload Unload;
    UnityLoggingLog Log;
} UnityLoggingPluginAPI;

UNITY_LOGGING_PLUGIN_API UnityLoggingStatus unity_logging_plugin_get_api(UnityLoggingPluginAPI* api, uint32_t version);

You can enable the logging plug-inA set of code created outside of Unity that creates functionality in Unity. There are two kinds of plug-ins you can use in Unity: Managed plug-ins (managed .NET assemblies created with tools like Visual Studio) and Native plug-ins (platform-specific native code libraries). More info
See in Glossary by providing a Player argument -platform-hmi-log-plugin and specifying the path to the plug-in’s shared library. The shared library must be accessible to the dynamic loader allowing it to be loaded using dlopen and initialized. For more information, refer to Command line arguments for logging.

If you set the -logfile argument together with the logging plug-in argument, the plug-in initializes, logs a single test message, and always results in a plug-in error. These steps are logged to help identify possible issues.

If the plug-in fails to initialize, Unity returns an error exit code by default. In this case, you can use the -platform-hmi-log-disable-on-plugin-failure argument to keep the Player running without any log output.

Note: Logging plug-in samples are available on request with embedded platforms support contract. To request access, contact the embedded platforms support team.

Integrate the plug-in with Logging Player setting

You can configure the logging plug-in to integrate with the Logging Player setting available for the embedded Linux and QNX platforms. To do so, consider the following steps and refer to the following code example:

  1. Use the SettingsProvider class to add the Logging setting.
  2. Use a class name that ends with PluginBuildPostProcessor.
  3. Make sure the signature of the ProcessConfiguration method matches the format mentioned in the following code example.
  4. Set the plug-in library using the platform-hmi-log-plugin argument.
namespace MyPluginNamespace
{
    public static class MyPluginBuildPostProcessor
    {
        private const string LoggingPluginKey = "platform-hmi-log-plugin";
        public static void ProcessConfiguration(Action<string, string> setValue)
        {
            // Set the shared library name for the plugin
            setValue(LoggingPluginKey, "mylogplugin.so");

            // (Optional) Set specific key values for the plugin
            setValue("my-plugin-setting", "42");
        }
    }

}

Additional resources

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Standard log output overview
Command line arguments for logging
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