perf-log-decorator

Typescript decorator for logging perfomance of methods. Includes separate decoratores for logging syncronous methods and methods that return promises.

Install

$ npm install --save perf-log-decorator

API

Decorators

• @PerfLog.Performance(string) => Will log how long the method takes using the input string as a key. If the key is not provided, the default key is [className].[methodName]
• @PerfLog.PromisePerformance(string) => Will log how long the promise returned by the method takes to resolve using the input string as a key. Both decorators can take an optional second parameter to replace the call to console.log with a custom method.

Additional global utility methods

• GetLogStatistics() => Will return an array with statistics about each method that is tracked.
• SetDefaultLogMethod(LogMethod) => Sets the default log method for all decorators. Must be called before the classes are defined. Can still be overridden by the decorator instance

Log Statistics

The following statistics are kept track of by a global log manager

• Number of successful calls
• Min\max runtime of the successful calls
• Average runtime of the successful calls
• Standard deviation of the runtime of successful calls
• Number of failed calls
• Min\max runtime of the failed calls
• Average runtime of the failed calls
• Standard deviation of the runtime of failed calls

Performance notes

Expect the decorator to add ~0.2ms to every call to the function. To test this in your use case, just add the decorator to a method twice with different tags. The difference between the two averages is roughly how long the decorator is taking.

Example

class Test { 

    @PerfLog.PromisePerformance("test1")
    public longPromiseMethod(): Promise<string> {
        return new Promise((resolve) => {
            setTimeout(() => {
                resolve();
            }, 5000);
        });
    }

    @PerfLog.Performance("test2")
    public longSyncronousMethod() {
        for (let i = 0; i < 100000000; i++) {

        }
    }
}

// examine the logs
const logs = PerfLog.GetLogStatistics();

##Extension You can install the Performance Log Display Chrome extension to display the log results.