Add support for dropwizard input format (#2846)

internal/templating/template.go

@@ -0,0 +1,148 @@
+package templating
+
+import (
+	"fmt"
+	"strings"
+)
+
+// Template represents a pattern and tags to map a metric string to a influxdb Point
+type Template struct {
+	separator         string
+	parts             []string
+	defaultTags       map[string]string
+	greedyField       bool
+	greedyMeasurement bool
+}
+
+// apply extracts the template fields from the given line and returns the measurement
+// name, tags and field name
+func (t *Template) Apply(line string, joiner string) (string, map[string]string, string, error) {
+	fields := strings.Split(line, t.separator)
+	var (
+		measurement []string
+		tags        = make(map[string][]string)
+		field       []string
+	)
+
+	// Set any default tags
+	for k, v := range t.defaultTags {
+		tags[k] = append(tags[k], v)
+	}
+
+	// See if an invalid combination has been specified in the template:
+	for _, tag := range t.parts {
+		if tag == "measurement*" {
+			t.greedyMeasurement = true
+		} else if tag == "field*" {
+			t.greedyField = true
+		}
+	}
+	if t.greedyField && t.greedyMeasurement {
+		return "", nil, "",
+			fmt.Errorf("either 'field*' or 'measurement*' can be used in each "+
+				"template (but not both together): %q",
+				strings.Join(t.parts, joiner))
+	}
+
+	for i, tag := range t.parts {
+		if i >= len(fields) {
+			continue
+		}
+		if tag == "" {
+			continue
+		}
+
+		switch tag {
+		case "measurement":
+			measurement = append(measurement, fields[i])
+		case "field":
+			field = append(field, fields[i])
+		case "field*":
+			field = append(field, fields[i:]...)
+			break
+		case "measurement*":
+			measurement = append(measurement, fields[i:]...)
+			break
+		default:
+			tags[tag] = append(tags[tag], fields[i])
+		}
+	}
+
+	// Convert to map of strings.
+	outtags := make(map[string]string)
+	for k, values := range tags {
+		outtags[k] = strings.Join(values, joiner)
+	}
+
+	return strings.Join(measurement, joiner), outtags, strings.Join(field, joiner), nil
+}
+
+func NewDefaultTemplateWithPattern(pattern string) (*Template, error) {
+	return NewTemplate(DefaultSeparator, pattern, nil)
+}
+
+// NewTemplate returns a new template ensuring it has a measurement
+// specified.
+func NewTemplate(separator string, pattern string, defaultTags map[string]string) (*Template, error) {
+	parts := strings.Split(pattern, separator)
+	hasMeasurement := false
+	template := &Template{
+		separator:   separator,
+		parts:       parts,
+		defaultTags: defaultTags,
+	}
+
+	for _, part := range parts {
+		if strings.HasPrefix(part, "measurement") {
+			hasMeasurement = true
+		}
+		if part == "measurement*" {
+			template.greedyMeasurement = true
+		} else if part == "field*" {
+			template.greedyField = true
+		}
+	}
+
+	if !hasMeasurement {
+		return nil, fmt.Errorf("no measurement specified for template. %q", pattern)
+	}
+
+	return template, nil
+}
+
+// templateSpec is a template string split in its constituent parts
+type templateSpec struct {
+	separator string
+	filter    string
+	template  string
+	tagstring string
+}
+
+// templateSpecs is simply an array of template specs implementing the sorting interface
+type templateSpecs []templateSpec
+
+// Less reports whether the element with
+// index j should sort before the element with index k.
+func (e templateSpecs) Less(j, k int) bool {
+	if len(e[j].filter) == 0 && len(e[k].filter) == 0 {
+		jlength := len(strings.Split(e[j].template, e[j].separator))
+		klength := len(strings.Split(e[k].template, e[k].separator))
+		return jlength < klength
+	}
+	if len(e[j].filter) == 0 {
+		return true
+	}
+	if len(e[k].filter) == 0 {
+		return false
+	}
+
+	jlength := len(strings.Split(e[j].template, e[j].separator))
+	klength := len(strings.Split(e[k].template, e[k].separator))
+	return jlength < klength
+}
+
+// Swap swaps the elements with indexes i and j.
+func (e templateSpecs) Swap(i, j int) { e[i], e[j] = e[j], e[i] }
+
+// Len is the number of elements in the collection.
+func (e templateSpecs) Len() int { return len(e) }