Function parseJavaSamples

profile/legacy_java_profile.go:167–233

parseJavaSamples parses the samples from a java profile and populates the Samples in a profile. Returns the remainder of the buffer after the samples.

(pType string, b []byte, p *Profile)

// populates the Samples in a profile. Returns the remainder of the
// buffer after the samples.
func parseJavaSamples(pType string, b []byte, p *Profile) ([]byte, map[uint64]*Location, error) {
	nextNewLine := bytes.IndexByte(b, byte('\n'))
	locs := make(map[uint64]*Location)
	for nextNewLine != -1 {
		line := string(bytes.TrimSpace(b[0:nextNewLine]))
		if line != "" {
			sample := javaSampleRx.FindStringSubmatch(line)
			if sample == nil {
				// Not a valid sample, exit.
				return b, locs, nil
			}

			// Java profiles have data/fields inverted compared to other
			// profile types.
			var err error
			value1, value2, value3 := sample[2], sample[1], sample[3]
			addrs, err := parseHexAddresses(value3)
			if err != nil {
				return nil, nil, fmt.Errorf("malformed sample: %s: %v", line, err)
			}

			var sloc []*Location
			for _, addr := range addrs {
				loc := locs[addr]
				if locs[addr] == nil {
					loc = &Location{
						Address: addr,
					}
					p.Location = append(p.Location, loc)
					locs[addr] = loc
				}
				sloc = append(sloc, loc)
			}
			s := &Sample{
				Value:    make([]int64, 2),
				Location: sloc,
			}

			if s.Value[0], err = strconv.ParseInt(value1, 0, 64); err != nil {
				return nil, nil, fmt.Errorf("parsing sample %s: %v", line, err)
			}
			if s.Value[1], err = strconv.ParseInt(value2, 0, 64); err != nil {
				return nil, nil, fmt.Errorf("parsing sample %s: %v", line, err)
			}

			switch pType {
			case "heap":
				const javaHeapzSamplingRate = 524288 // 512K
				if s.Value[0] == 0 {
					return nil, nil, fmt.Errorf("parsing sample %s: second value must be non-zero", line)
				}
				s.NumLabel = map[string][]int64{"bytes": {s.Value[1] / s.Value[0]}}
				s.Value[0], s.Value[1] = scaleHeapSample(s.Value[0], s.Value[1], javaHeapzSamplingRate)
			case "contention":
				if period := p.Period; period != 0 {
					s.Value[0] = s.Value[0] * p.Period
					s.Value[1] = s.Value[1] * p.Period
				}