dgtvan / BridgeLogger

BridgeLogger

This is a proof of concept of how to bridge an existing ILogger.

Problem

Once I was given a library named ExternalLibrary, I had to add it as a service to the project implementing Dependency Injection. The library has a contructor definition like below

class ExternalLibrary
{
    public ExternalLibrary(ILogger<ExternalLibrary> logger, ...);
}

All services in the project had to log with a pre-defined format below. All logs will be pushed to a Serilog's ElasticSearch sink. Any log does not follow the format, the log consumer will have an issue of parsing it later.

Log.LogInformation("{@ActionGroup} {@ActionTaken}", "GroupA", "ActionA");
Log.LogError("{@ActionGroup} {@ActionTaken}", "GroupA", "ActionA");
...

The problem came when I had to handle log messages from ExternalLibrary but log messages did not follow the pre-defined format. Here is how the log messages from ExternalLibrary were logged:

Log.LogInformation("Begin to fetching...");
Log.LogError("An error occured while ...");
...

Solution

I created a bridge logger injected to ExternalLibrary, it accepted a delegate CustomLogFormatter so that it could modify the format as well as the arguments of all log messages going through it.

The definition of the delegate CustomLogFormatter:

(string, object[]) CustomLogFormatter(string originalFormat, List<object> originalArguments)
{
    // ...
    // Custom implementation
    // ...
    
    return (newFormat, newArguments);
}

The illustration below shows how the bridge logger worked.

Next

• Create a benchmark showing how bad the performance affected by the bridge logger.
• Optimize the bridge implementation or find a different approach to solve the problem.