node-hdr-histogram-napi

A Node.js native addon for HdrHistogram using N-API.

This module is in active development and is not yet ready for production use.

Background

This module, which is implemented using N-API, is meant to be an API-compatable alternative to the native-hdr-histogram module which is implemented using NAN. Both modules implement Node.js native addons that wrap the HdrHistogram_c library.

The majority of the files in this module are generated by an automated tool that parses the source C files and generates the binding files. The objective is to create a very light-weight wrapper to the native C functions and then augment these native classes with JavaScript as necessary.

In this module, HdrHistogram and HdrHistogramIterator are native classes implemented using N-API. The JavaScript Histogram class extends the native HdrHistogram class and implements the additional methods necessary to achieve compatibility with the native-hdr-histogram Histogram class.

Implementation

This table shows the existing Histogram methods available in the native-hdr-histogram module (NAN) and the corresponding and additional methods available in this module (N-API).

NAN	HdrHistogram_c Function	N-API
record	hdr_record_value	record
min	hdr_min	min
max	hdr_max	max
mean	hdr_mean	mean
stddev	hdr_stddev	stddev
percentile	hdr_value_at_percentile	percentile
encode	hdr_log_encode	encode ‡
decode †	hdr_log_decode	decode †‡
percentiles	hdr_iter_percentile_init hdr_iter_next	percentiles ‡
reset	hdr_reset	reset
	hdr_reset_internal_counters	resetInternalCounters
	hdr_get_memory_size	getMemorySize
	hdr_record_value_atomic	recordAtomic
	hdr_record_values	recordValues
	hdr_record_values_atomic	recordValuesAtomic
	hdr_record_corrected_value	recordCorrectedValue
	hdr_record_corrected_value_atomic	recordCorrectedValueAtomic
	hdr_record_corrected_values	recordCorrectedValues
	hdr_record_corrected_values_atomic	recordCorrectedValuesAtomic
	hdr_add	add
	hdr_values_are_equivalent	valuesAreEquivalent
	hdr_lowest_equivalent_value	lowestEquivalentValue
	hdr_count_at_value	countAtValue
	hdr_log_encode	getEncoded
	hdr_log_decode	setEncoded

† This is a static method.

‡ Implemented in JavaScript using the native N-API classes and accessor methods.

Plan

The immediate plan is to continue enhancing this module until it's ready for production use. These steps are:

• Modify the Histogram constructor so that it is completely compatible with the native-hdr-histogram version.
• Complete detailed verification on the code.
• Generate configuration information to support prebuild for creating and uploading native binaries.
• Build out unit tests.
• Implement GitHub CI to prebuild for various architectures.
• Generate complete documentation.
• Publish to npm.