inline-histogram

Simple utility for visualizing a histogram in a single line of text, using box-drawing-characters.

Features:

• generate normalized text histograms:
  • Vanilla:
    • ▁▂▃▅▆▇
  • Labels:
    • 0s▕ ▁▂▃▃▅▆▇ ▏5s
  • Indicator:
    • ▁▂▃▅⭐▆▇

The library is primarily intended for simple visualization of HTTP request durations in logs.

License

Apache 2.0

Obtain

The project is built with Maven and is available on the central Maven repository.

Maven coordinates

Add the property

<inline-histogram.version>1.0.0</inline-histogram.version>

then add

<dependency>
    <groupId>com.github.skjolber.histogram</groupId>
    <artifactId>inline</artifactId>
    <version>${inline-histogram.version}</version>
</dependency>

or

Gradle coordinates

For

ext {
  inlineHistogramVersion = '1.0.0'
}

add

api ("com.github.skjolber.histogram:inline:${inlineHistogramVersion}")

Usage

So we want to create a HistogramCharSequence. The DefaultHistogram implementation is a fixed size histogram with thread-safe counters.

DefaultHistogram histogram = DefaultHistogram.newBuilder()
	.add(0, "0s")
	.add(250)
	.add(500)
	.add(750)
	.add(1000, "1000s")
	.build();

then update by index

histogram.incrementByIndex(1);

or value

histogram.incrementByValue(444);

when it is time to see the results, get the HistogramCharSequence and print it.

HistogramCharSequence sequence = HistogramCharSequenceFactory.newInstance(histogram);

LOGGER.info("https://... HTTP 200 in 444ms " + sequence);

Note that resolution is limited to 9 levels.

Supported tools

Support depends on the font used in the log accumulation tool. This implementation has been tested with

• GCP's Stackdriver

Example:

• 0 to 10 second histogram, with
• 250 ms slots, and
• labels, with
• indicator (⭐) for the current request