com.couchbase.client.core.deps.org.HdrHistogram.AbstractHistogramLogReader Maven / Gradle / Ivy
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/**
* Written by Gil Tene of Azul Systems, and released to the public domain,
* as explained at http://creativecommons.org/publicdomain/zero/1.0/
*
* @author Gil Tene
*/
package com.couchbase.client.core.deps.org.HdrHistogram;
import javax.xml.bind.DatatypeConverter;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.InputStream;
import java.nio.ByteBuffer;
import java.util.Locale;
import java.util.Scanner;
import java.util.zip.DataFormatException;
class AbstractHistogramLogReader {
protected final Scanner scanner;
private double startTimeSec = 0.0;
/**
* Constructs a new HistogramLogReader that produces intervals read from the specified file name.
* @param inputFileName The name of the file to read from
* @throws java.io.FileNotFoundException when unable to find inputFileName
*/
public AbstractHistogramLogReader(final String inputFileName) throws FileNotFoundException {
scanner = new Scanner(new File(inputFileName));
initScanner();
}
/**
* Constructs a new HistogramLogReader that produces intervals read from the specified InputStream.
* @param inputStream The InputStream to read from
*/
public AbstractHistogramLogReader(final InputStream inputStream) {
scanner = new Scanner(inputStream);
initScanner();
}
/**
* Constructs a new HistogramLogReader that produces intervals read from the specified file.
* @param inputFile The File to read from
* @throws java.io.FileNotFoundException when unable to find inputFile
*/
public AbstractHistogramLogReader(final File inputFile) throws FileNotFoundException {
scanner = new Scanner(inputFile);
initScanner();
}
private void initScanner() {
scanner.useLocale(Locale.US);
scanner.useDelimiter("[ ,\\r\\n]");
}
/**
* get the latest start time found in the file so far (or 0.0),
* per the log file format explained above. Assuming the "#[StartTime:" comment
* line precedes the actual intervals recorded in the file, getStartTimeSec() can
* be safely used after each interval is read to determine's the offset of that
* interval's timestamp from the epoch.
* @return latest Start Time found in the file (or 0.0 if non found)
*/
public double getStartTimeSec() {
return startTimeSec;
}
protected void setStartTimeSec(double startTimeSec) {
this.startTimeSec = startTimeSec;
}
/**
* Read the next interval histogram from the log, if interval falls within a time range.
*
* Returns a histogram object if an interval line was found with an
* associated start timestamp value that falls between startTimeSec and
* endTimeSec, or null if no such interval line is found. Note that
* the range is assumed to be in seconds relative to the actual
* timestamp value found in each interval line in the log, and not
* in absolute time.
*
* Timestamps are assumed to appear in order in the log file, and as such
* this method will return a null upon encountering a timestamp larger than
* rangeEndTimeSec.
*
* The histogram returned will have it's timestamp set to the absolute
* timestamp calculated from adding the interval's indicated timestamp
* value to the latest [optional] start time found in the log.
*
* Upon encountering any unexpected format errors in reading the next
* interval from the file, this method will return a null.
* @param startTimeSec The (non-absolute time) start of the expected
* time range, in seconds.
* @param endTimeSec The (non-absolute time) end of the expected time
* range, in seconds.
* @return a histogram, or a null if no appropriate interval found
*/
public EncodableHistogram nextIntervalHistogram(final Double startTimeSec,
final Double endTimeSec) {
return nextIntervalHistogram(startTimeSec, endTimeSec, false);
}
/**
* Read the next interval histogram from the log, if interval falls within an absolute time range
*
* Returns a histogram object if an interval line was found with an
* associated absolute start timestamp value that falls between
* absoluteStartTimeSec and absoluteEndTimeSec, or null if no such
* interval line is found.
*
* Timestamps are assumed to appear in order in the log file, and as such
* this method will return a null upon encountering a timestamp larger than
* rangeEndTimeSec.
*
* The histogram returned will have it's timestamp set to the absolute
* timestamp calculated from adding the interval's indicated timestamp
* value to the latest [optional] start time found in the log.
*
* Absolute timestamps are calculated by adding the timestamp found
* with the recorded interval to the [latest, optional] start time
* found in the log. The start time is indicated in the log with
* a "#[StartTime: " followed by the start time in seconds.
*
* Upon encountering any unexpected format errors in reading the next
* interval from the file, this method will return a null.
* @param absoluteStartTimeSec The (absolute time) start of the expected
* time range, in seconds.
* @param absoluteEndTimeSec The (absolute time) end of the expected
* time range, in seconds.
* @return A histogram, or a null if no appropriate interval found
*/
public EncodableHistogram nextAbsoluteIntervalHistogram(final Double absoluteStartTimeSec,
final Double absoluteEndTimeSec) {
return nextIntervalHistogram(absoluteStartTimeSec, absoluteEndTimeSec, true);
}
/**
* Read the next interval histogram from the log. Returns a Histogram object if
* an interval line was found, or null if not.
*
Upon encountering any unexpected format errors in reading the next interval
* from the file, this method will return a null.
* @return a DecodedInterval, or a null if no appropriate interval found
*/
public EncodableHistogram nextIntervalHistogram() {
return nextIntervalHistogram(0.0, Long.MAX_VALUE * 1.0, true);
}
private EncodableHistogram nextIntervalHistogram(final Double rangeStartTimeSec,
final Double rangeEndTimeSec, boolean absolute) {
while (scanner.hasNextLine()) {
try {
if (scanner.hasNext("\\#.*")) {
// comment line
if (scanner.hasNext("#\\[StartTime:")) {
scanner.next("#\\[StartTime:");
if (scanner.hasNextDouble()) {
setStartTimeSec(scanner.nextDouble()); // start time represented as seconds since epoch
}
}
scanner.nextLine();
continue;
}
if (scanner.hasNext("\"StartTimestamp\".*")) {
// Legend line
scanner.nextLine();
continue;
}
// Decode: startTimestamp, intervalLength, maxTime, histogramPayload
final double offsetStartTimeStampSec = scanner.nextDouble(); // Timestamp start is expect to be in seconds
final double absoluteStartTimeStampSec = getStartTimeSec() + offsetStartTimeStampSec;
final double intervalLengthSec = scanner.nextDouble(); // Timestamp length is expect to be in seconds
final double offsetEndTimeStampSec = offsetStartTimeStampSec + intervalLengthSec;
final double absoluteEndTimeStampSec = getStartTimeSec() + offsetEndTimeStampSec;
final double startTimeStampToCheckRangeOn = absolute ? absoluteStartTimeStampSec : offsetStartTimeStampSec;
if (startTimeStampToCheckRangeOn < rangeStartTimeSec) {
scanner.nextLine();
continue;
}
if (startTimeStampToCheckRangeOn > rangeEndTimeSec) {
return null;
}
scanner.nextDouble(); // Skip maxTime field, as max time can be deduced from the histogram.
final String compressedPayloadString = scanner.next();
final ByteBuffer buffer = ByteBuffer.wrap(
DatatypeConverter.parseBase64Binary(compressedPayloadString));
EncodableHistogram histogram = Histogram.decodeFromCompressedByteBuffer(buffer, 0);
histogram.setStartTimeStamp((long) (absoluteStartTimeStampSec * 1000.0));
histogram.setEndTimeStamp((long) (absoluteEndTimeStampSec * 1000.0));
return histogram;
} catch (java.util.NoSuchElementException ex) {
return null;
} catch (DataFormatException ex) {
return null;
}
}
return null;
}
}