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import { NO_TAG } from "./Histogram";
import { encodeIntoCompressedBase64 } from "./encoding";
import { floatFormatter } from "./formatters";
import Histogram from "./Histogram";
export interface Writable {
(c: string): void;
}
const HISTOGRAM_LOG_FORMAT_VERSION = "1.3";
const timeFormatter = floatFormatter(5, 3);
class HistogramLogWriter {
/**
* Base time to subtract from supplied histogram start/end timestamps when
* logging based on histogram timestamps.
* Base time is expected to be in msec since the epoch, as histogram start/end times
* are typically stamped with absolute times in msec since the epoch.
*/
baseTime = 0;
constructor(private log: Writable) {}
/**
* Output an interval histogram, with the given timestamp information and the [optional] tag
* associated with the histogram, using a configurable maxValueUnitRatio. (note that the
* specified timestamp information will be used, and the timestamp information in the actual
* histogram will be ignored).
* The max value reported with the interval line will be scaled by the given maxValueUnitRatio.
* @param startTimeStampSec The start timestamp to log with the interval histogram, in seconds.
* @param endTimeStampSec The end timestamp to log with the interval histogram, in seconds.
* @param histogram The interval histogram to log.
* @param maxValueUnitRatio The ratio by which to divide the histogram's max value when reporting on it.
*/
outputIntervalHistogram(
histogram: Histogram,
startTimeStampSec = (histogram.startTimeStampMsec - this.baseTime) / 1000,
endTimeStampSec = (histogram.endTimeStampMsec - this.baseTime) / 1000,
maxValueUnitRatio = 1000
) {
const base64 = encodeIntoCompressedBase64(histogram);
const start = timeFormatter(startTimeStampSec);
const duration = timeFormatter(endTimeStampSec - startTimeStampSec);
const max = timeFormatter(histogram.maxValue / maxValueUnitRatio);
const lineContent = `${start},${duration},${max},${base64}\n`;
if (histogram.tag && histogram.tag !== NO_TAG) {
this.log(`Tag=${histogram.tag},${lineContent}`);
} else {
this.log(lineContent);
}
}
/**
* Log a comment to the log.
* Comments will be preceded with with the '#' character.
* @param comment the comment string.
*/
outputComment(comment: string) {
this.log(`#${comment}\n`);
}
/**
* Log a start time in the log.
* @param startTimeMsec time (in milliseconds) since the absolute start time (the epoch)
*/
outputStartTime(startTimeMsec: number) {
this.outputComment(
`[StartTime: ${floatFormatter(
5,
3
)(startTimeMsec / 1000)} (seconds since epoch), ${new Date(
startTimeMsec
)}]\n`
);
}
/**
* Output a legend line to the log.
*/
outputLegend() {
this.log(
'"StartTimestamp","Interval_Length","Interval_Max","Interval_Compressed_Histogram"\n'
);
}
/**
* Output a log format version to the log.
*/
outputLogFormatVersion() {
this.outputComment(
"[Histogram log format version " + HISTOGRAM_LOG_FORMAT_VERSION + "]"
);
}
}
export default HistogramLogWriter;