Add TRITONSERVER_ServerOptionsSetLogCallback API

[nbarbier-amira]

Adds a C API for registering a log callback, allowing applications using the Triton C API to capture log messages programmatically.

Motivation

Applications embedding Triton often have their own logging infrastructure and need to integrate Triton's logs rather than having them go to stdout/stderr or a separate file. The current workarounds (parsing log files, named pipes) are clunky and lose metadata like log levels. See triton-inference-server/server#8304.

API

typedef void (*TRITONSERVER_LogCallbackFn_t)(
    TRITONSERVER_LogLevel level, const char* filename, int line,
    const char* msg, void* userp);

TRITONSERVER_Error* TRITONSERVER_ServerOptionsSetLogCallback(
    TRITONSERVER_ServerOptions* options,
    TRITONSERVER_LogCallbackFn_t callback_fn, 
    void* userp,
    bool replace_default_logger);

Usage

void my_callback(TRITONSERVER_LogLevel level, const char* file, 
                 int line, const char* msg, void* ctx) {
    // route to your logging system
}

TRITONSERVER_ServerOptionsSetLogCallback(opts, my_callback, NULL, true);

Setting replace_default_logger=true suppresses default stdout/stderr output. Setting it to false calls the callback in addition to normal logging.

Dependencies

Requires triton-inference-server/common#149 for the underlying Logger changes.