ydb/contrib/libs/hdr_histogram/README.md

HdrHistogram_c: 'C' port of High Dynamic Range (HDR) Histogram

HdrHistogram

Windows Build:

This port contains a subset of the functionality supported by the Java implementation. The current supported features are:

• Standard histogram with 64 bit counts (32/16 bit counts not supported)
• All iterator types (all values, recorded, percentiles, linear, logarithmic)
• Histogram serialisation (encoding version 1.2, decoding 1.0-1.2)
• Reader/writer phaser and interval recorder

Features not supported, but planned

• Auto-resizing of histograms

Features unlikely to be implemented

• Double histograms
• Atomic/Concurrent histograms
• 16/32 bit histograms

Simple Tutorial

Recording values

#include <hdr_histogram.h> 
 
struct hdr_histogram* histogram; 
 
// Initialise the histogram 
hdr_init( 
    1,  // Minimum value 
    INT64_C(3600000000),  // Maximum value 
    3,  // Number of significant figures 
    &histogram)  // Pointer to initialise 
 
// Record value 
hdr_record_value( 
    histogram,  // Histogram to record to 
    value)  // Value to record 
 
// Record value n times 
hdr_record_values( 
    histogram,  // Histogram to record to 
    value,  // Value to record 
    10)  // Record value 10 times 
 
// Record value with correction for co-ordinated omission. 
hdr_record_corrected_value( 
    histogram,  // Histogram to record to 
    value,  // Value to record 
    1000)  // Record with expected interval of 1000. 
 
// Print out the values of the histogram 
hdr_percentiles_print( 
    histogram, 
    stdout,  // File to write to 
    5,  // Granularity of printed values 
    1.0,  // Multiplier for results 
    CLASSIC);  // Format CLASSIC/CSV supported. 

More examples

For more detailed examples of recording and logging results look at the hdr_decoder and hiccup examples. You can run hiccup and decoder and pipe the results of one into the other.

$ ./examples/hiccup | ./examples/hdr_decoder