timer-set

Facilitates code timing for instrumentation and other purposes, with very small footprint in both code and resource usage. Construction and reporting require only a single line each, regardless of how many timers are included in a set. Tested on Unix and Windows.

Usage (extract from main-col-group.js)

const TimerSet = require('timer-set');

const tsColGroup = new TimerSet('ColGroup Timers');
const grp = new ColGroup(INPUT_FILE, DELIM, COL);
tsColGroup.incrementTime('ColGroup');
.
.
.
grp.prList('value', grp.sortByValue());
tsColGroup.incrementTime('sortByValue');

console.log(tsColGroup.formatResults());

This will create a timer set and time the sections, with listing at the end:

Timer set: ColGroup Timers, constructed at Mon Oct 01 2018 14:25:38, written at Mon Oct 01 2018 14:25:38
========================================================================================================
Timer           Elapsed         USR         SYS       Calls       Ela/Call       USR/Call       SYS/Call
-----------  ----------  ----------  ----------  ----------  -------------  -------------  -------------
ColGroup           0.05        0.00        0.01           1        0.04800        0.00387        0.00775
listAsIs           0.09        0.01        0.02           1        0.08500        0.01150        0.01750
sortByKey          0.06        0.01        0.02           1        0.05600        0.00788        0.01762
sortByValue        0.05        0.00        0.01           1        0.05100        0.00200        0.00975
(Other)            0.00        0.00        0.00           1        0.00000        0.00000        0.00000
-----------  ----------  ----------  ----------  ----------  -------------  -------------  -------------
Total              0.24        0.03        0.05           5        0.04800        0.00505        0.01052
-----------  ----------  ----------  ----------  ----------  -------------  -------------  -------------
[Timer timed (per call in ms): Elapsed: 0.16832, USR: 0.00000, SYS: 0.01856]

To run the example from root (timer-set) folder:

Unix

$ node examples/col-group/main-col-group

Windows

$ node examples\col-group\main-col-group

API

const TimerSet = require('timer-set');

const ts = new TimerSet(tsName);

Constructs a new timer set ts with name tsName.

ts.incrementTime(timerName);

Increments the timing statistics (elapsed, user and system CPU, and number of calls) for a timer timerName within the timer set ts with the times passed since the previous call to incrementTime, initTime or the constructor of the timer set instance. Resets the statistics for timer set ts to the current time, so that the next call to incrementTime measures from this point for its increment.

ts.initTime();

Resets the statistics for timer set ts to the current time, so that the next call to incrementTime measures from this point for its increment. This is only used where there are gaps between sections to be timed.

ts.getTimers();

Returns the results for timer set ts in an array of objects, with fields:

• timer: timer name
• ela: elapsed time in ms
• usr: user CPU time in ms
• sys: system CPU time in ms
• calls: number of calls

After a record for each named timer, in order of creation, there are two calculated records:

• Other: differences between Total values and the sums of the named timers
• Total: totals calculated from the times at timer set construction

ts.formatTimers(time_width, time_dp, time_ratio_dp, calls_width);

Returns the results for timer set ts in an array of formatted strings, including column headers and formatting lines, with fields as in getTimers, but with times in seconds, and per call values added, with parameters:

• time_width: width of time fields (excluding decimal places), default 8
• time_dp: decimal places to show for absolute time fields, default 2
• time_ratio_dp: decimal places to show for per call time fields, default 5
• calls_width: width of calls field, default 10

TimerSet.getSelfTimer();

Static method to time the incrementTime method as a way of estimating the overhead in using the timer set. Constructs a timer set instance and calls incrementTime on it within a loop until 0.1s has elapsed.

Returns an object, with fields:

• ela: elapsed time per call in ms
• usr: user CPU time per call in ms
• sys: system CPU time per call in ms

TimerSet.formatSelfTimer(time_width, time_dp, time_ratio_dp);

Static method to return the results from getSelfTimer in a formatted string, with parameters as formatTimers (but any extra spaces are trimmed here).

ts.formatResults(time_width, time_dp, time_ratio_dp, calls_width);

Returns the results for timer set ts in a formatted string, with parameters as formatTimers. It uses the array returned from formatTimers and includes a header line with timer set construction and writing times, and a footer of the self-timing values.

Install

With npm installed, run

$ npm install timer-set

Unit testing

The npm package trapit is required to run the unit tests.

$ npm install trapit
$ npm test

The package is tested using the Math Function Unit Testing design pattern (See also below). In this approach, a 'pure' wrapper function is constructed that takes input parameters and returns a value, and is tested within a loop over scenario records read from a JSON file.

The wrapper function represents a generalised transactional use of the package in which multiple timer sets may be constructed, and then timings carried out and reported on at the end of the transaction.

This kind of package would usually be thought hard to unit-test, with CPU and elapsed times being inherently non-deterministic. However, this is a good example of the power of the design pattern that I recently introduced: One of the inputs is a yes/no flag indicating whether to mock the system timing calls, or not. The function calls used to return epochal CPU and elapsed times are actually parameters that take the (Windows) system functions as defaults, while in the mocked case deterministic versions are supplied by the test driver, that read the values to return from the input scenario data. In this way we can test correctness of the timing aggregations, independence of timer sets etc. using the deterministic functions; on the other hand, one of the key benefits of automated unit testing is to test the actual dependencies, and we do this in the non-mocked case by passing in 'sleep' times to the wrapper function and testing the outputs against ranges of values.

Operating Systems

The package works on both Unix and Windows and has been tested on:

Windows

Windows 10, node v8.1.4 and node v10.6.0

Unix

Oracle Linux Server 7.5 (via Virtualbox on Windows host), node v8.12.0

See also

• trapit (unit testing package)
• Javascript timer-set package on GitHub
• Code Timing and Object Orientation and Zombies, Brendan Furey, November 2010

License

ISC