Node Trace Module

This module provides a pair of TraceBroker classes for use in Node, one native (C++) and one JS. These brokers provide Trace/trace methods for components to publish trace events, and Register/on methods for registering trace listeners. Listeners in JS are callbacks, and in C++ are function pointers.

The C++ and JS brokers are wired together so that traces from native components are published to JS listeners; and vice versa.

Listeners are invoked when traces are received through Trace/trace. By default listeners are invoked on the same thread and within the same "tick" as the publication, which is the behavior of EventEmitter. A TraceNextTick function instead delays publication till the next tick.

Quick Start

1. Install node-gyp (npm install -g node-gyp).
2. Run node-gyp build --debug from this directory.
3. Run node ./examples/trace_example.js.

You'll see a log from a JS listener registered within trace_example.js, as well as a log from a native listener registered by calling enabledNativeConsoleListener() in lib/trace.js.

Native TraceBroker

To add a native listener to your app, use the following pattern:

#include "trace_broker.h"

# Declare and define a C function with the following signature:
void ConsoleListener(const char* category, std::map<const char*, const char*> trace_map);
void ConsoleListener(const char* category, std::map<const char*, const char*> trace_map) {
  std::cout << "Category: " << category << std::endl;
  for (auto it = trace_map.begin(); it != trace_map.end(); ++it) {
    std::cout << it->first << ": " << it->second << std::endl;
  }
  std::cout << std::endl;
}

# Register the previous function as a listener:
TraceBroker::Singleton()->RegisterListener(&ConsoleListener);

To publish traces from native components in your app, use the following pattern:

#include "trace_broker.h"

TraceBroker::Singleton->Trace("category_name", {{"message": "myMessage"}, {"extra": "moreInfo"}});

JS TraceBroker

See ./examples/trace_example.js for an example of how to subscribe to and publish traces in JS scripts.

More

This is a work in progress.