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io.prometheus.metrics.model.snapshots.Labels Maven / Gradle / Ivy
Data model for read-only immutable Prometheus metrics snapshots.
package io.prometheus.metrics.model.snapshots;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;
import java.util.stream.Stream;
import static io.prometheus.metrics.model.snapshots.PrometheusNaming.isValidLabelName;
import static io.prometheus.metrics.model.snapshots.PrometheusNaming.prometheusName;
/**
* Immutable set of name/value pairs, sorted by name.
*/
public class Labels implements Comparable, Iterable {
public static final Labels EMPTY;
static {
String[] names = new String[]{};
String[] values = new String[]{};
EMPTY = new Labels(names, names, values);
}
// prometheusNames is the same as names, but dots are replaced with underscores.
// Labels is sorted by prometheusNames.
// If names[i] does not contain a dot, prometheusNames[i] references the same String as names[i]
// so that we don't have unnecessary duplicates of strings.
// If none of the names contains a dot, then prometheusNames references the same array as names
// so that we don't have unnecessary duplicate arrays.
private final String[] prometheusNames;
private final String[] names;
private final String[] values;
private Labels(String[] names, String[] prometheusNames, String[] values) {
this.names = names;
this.prometheusNames = prometheusNames;
this.values = values;
}
public boolean isEmpty() {
return this == EMPTY || this.equals(EMPTY);
}
/**
* Create a new Labels instance.
* You can either create Labels with one of the static {@code Labels.of(...)} methods,
* or you can use the {@link Labels#builder()}.
*
* @param keyValuePairs as in {@code {name1, value1, name2, value2}}. Length must be even.
* {@link PrometheusNaming#isValidLabelName(String)} must be true for each name.
* Use {@link PrometheusNaming#sanitizeLabelName(String)} to convert arbitrary strings
* to valid label names. Label names must be unique (no duplicate label names).
*/
public static Labels of(String... keyValuePairs) {
if (keyValuePairs.length % 2 != 0) {
throw new IllegalArgumentException("Key/value pairs must have an even length");
}
if (keyValuePairs.length == 0) {
return EMPTY;
}
String[] names = new String[keyValuePairs.length / 2];
String[] values = new String[keyValuePairs.length / 2];
for (int i = 0; 2 * i < keyValuePairs.length; i++) {
names[i] = keyValuePairs[2 * i];
values[i] = keyValuePairs[2 * i + 1];
}
String[] prometheusNames = makePrometheusNames(names);
sortAndValidate(names, prometheusNames, values);
return new Labels(names, prometheusNames, values);
}
// package private for testing
static String[] makePrometheusNames(String[] names) {
String[] prometheusNames = names;
for (int i=0; i names, List values) {
if (names.size() != values.size()) {
throw new IllegalArgumentException("Names and values must have the same size.");
}
if (names.size() == 0) {
return EMPTY;
}
String[] namesCopy = names.toArray(new String[0]);
String[] valuesCopy = values.toArray(new String[0]);
String[] prometheusNames = makePrometheusNames(namesCopy);
sortAndValidate(namesCopy, prometheusNames, valuesCopy);
return new Labels(namesCopy, prometheusNames, valuesCopy);
}
/**
* Create a new Labels instance.
* You can either create Labels with one of the static {@code Labels.of(...)} methods,
* or you can use the {@link Labels#builder()}.
*
* @param names label names. {@link PrometheusNaming#isValidLabelName(String)} must be true for each name.
* Use {@link PrometheusNaming#sanitizeLabelName(String)} to convert arbitrary strings
* to valid label names. Label names must be unique (no duplicate label names).
* @param values label values. {@code names.length} must be equal to {@code values.length}.
*/
public static Labels of(String[] names, String[] values) {
if (names.length != values.length) {
throw new IllegalArgumentException("Names and values must have the same length.");
}
if (names.length == 0) {
return EMPTY;
}
String[] namesCopy = Arrays.copyOf(names, names.length);
String[] valuesCopy = Arrays.copyOf(values, values.length);
String[] prometheusNames = makePrometheusNames(namesCopy);
sortAndValidate(namesCopy, prometheusNames, valuesCopy);
return new Labels(namesCopy, prometheusNames, valuesCopy);
}
/**
* Test if these labels contain a specific label name.
*
* Dots are treated as underscores, so {@code contains("my.label")} and {@code contains("my_label")} are the same.
*/
public boolean contains(String labelName) {
return get(labelName) != null;
}
/**
* Get the label value for a given label name.
*
* Returns {@code null} if the {@code labelName} is not found.
*
* Dots are treated as underscores, so {@code get("my.label")} and {@code get("my_label")} are the same.
*/
public String get(String labelName) {
labelName = prometheusName(labelName);
for (int i=0; i 0 && prometheusNames[i - 1].equals(prometheusNames[i])) {
throw new IllegalArgumentException(names[i] + ": duplicate label name");
}
}
}
private static void sort(String[] names, String[] prometheusNames, String[] values) {
// bubblesort
int n = prometheusNames.length;
for (int i = 0; i < n - 1; i++) {
for (int j = 0; j < n - i - 1; j++) {
if (prometheusNames[j].compareTo(prometheusNames[j + 1]) > 0) {
swap(j, j + 1, names, prometheusNames, values);
}
}
}
}
private static void swap(int i, int j, String[] names, String[] prometheusNames, String[] values) {
String tmp = names[j];
names[j] = names[i];
names[i] = tmp;
tmp = values[j];
values[j] = values[i];
values[i] = tmp;
if (prometheusNames != names) {
tmp = prometheusNames[j];
prometheusNames[j] = prometheusNames[i];
prometheusNames[i] = tmp;
}
}
@Override
public Iterator iterator() {
return asList().iterator();
}
public Stream stream() {
return asList().stream();
}
public int size() {
return names.length;
}
public String getName(int i) {
return names[i];
}
/**
* Like {@link #getName(int)}, but dots are replaced with underscores.
*
* This is used by Prometheus exposition formats.
*/
public String getPrometheusName(int i) {
return prometheusNames[i];
}
public String getValue(int i) {
return values[i];
}
/**
* Create a new Labels instance containing the labels of this and the labels of other.
* This and other must not contain the same label name.
*/
public Labels merge(Labels other) {
if (this.isEmpty()) {
return other;
}
if (other.isEmpty()) {
return this;
}
String[] names = new String[this.names.length + other.names.length];
String[] prometheusNames = names;
if (this.names != this.prometheusNames || other.names != other.prometheusNames) {
prometheusNames = new String[names.length];
}
String[] values = new String[names.length];
int thisPos = 0;
int otherPos = 0;
while (thisPos + otherPos < names.length) {
if (thisPos >= this.names.length) {
names[thisPos + otherPos] = other.names[otherPos];
values[thisPos + otherPos] = other.values[otherPos];
if (prometheusNames != names) {
prometheusNames[thisPos + otherPos] = other.prometheusNames[otherPos];
}
otherPos++;
} else if (otherPos >= other.names.length) {
names[thisPos + otherPos] = this.names[thisPos];
values[thisPos + otherPos] = this.values[thisPos];
if (prometheusNames != names) {
prometheusNames[thisPos + otherPos] = this.prometheusNames[thisPos];
}
thisPos++;
} else if (this.prometheusNames[thisPos].compareTo(other.prometheusNames[otherPos]) < 0) {
names[thisPos + otherPos] = this.names[thisPos];
values[thisPos + otherPos] = this.values[thisPos];
if (prometheusNames != names) {
prometheusNames[thisPos + otherPos] = this.prometheusNames[thisPos];
}
thisPos++;
} else if (this.prometheusNames[thisPos].compareTo(other.prometheusNames[otherPos]) > 0) {
names[thisPos + otherPos] = other.names[otherPos];
values[thisPos + otherPos] = other.values[otherPos];
if (prometheusNames != names) {
prometheusNames[thisPos + otherPos] = other.prometheusNames[otherPos];
}
otherPos++;
} else {
throw new IllegalArgumentException("Duplicate label name: '" + this.names[thisPos] + "'.");
}
}
return new Labels(names, prometheusNames, values);
}
/**
* Create a new Labels instance containing the labels of this and the label passed as name and value.
* The label name must not already be contained in this Labels instance.
*/
public Labels add(String name, String value) {
return merge(Labels.of(name, value));
}
/**
* Create a new Labels instance containing the labels of this and the labels passed as names and values.
* The new label names must not already be contained in this Labels instance.
*/
public Labels merge(String[] names, String[] values) {
if (this.equals(EMPTY)) {
return Labels.of(names, values);
}
String[] mergedNames = new String[this.names.length + names.length];
String[] mergedValues = new String[this.values.length + values.length];
System.arraycopy(this.names, 0, mergedNames, 0, this.names.length);
System.arraycopy(this.values, 0, mergedValues, 0, this.values.length);
System.arraycopy(names, 0, mergedNames, this.names.length, names.length);
System.arraycopy(values, 0, mergedValues, this.values.length, values.length);
String[] prometheusNames = makePrometheusNames(mergedNames);
sortAndValidate(mergedNames, prometheusNames, mergedValues);
return new Labels(mergedNames, prometheusNames, mergedValues);
}
public boolean hasSameNames(Labels other) {
return Arrays.equals(prometheusNames, other.prometheusNames);
}
public boolean hasSameValues(Labels other) {
return Arrays.equals(values, other.values);
}
@Override
public int compareTo(Labels other) {
int result = compare(prometheusNames, other.prometheusNames);
if (result != 0) {
return result;
}
return compare(values, other.values);
}
// Looks like Java doesn't have a compareTo() method for arrays.
private int compare(String[] array1, String[] array2) {
int result;
for (int i = 0; i < array1.length; i++) {
if (array2.length <= i) {
return 1;
}
result = array1[i].compareTo(array2[i]);
if (result != 0) {
return result;
}
}
if (array2.length > array1.length) {
return -1;
}
return 0;
}
private List asList() {
List result = new ArrayList<>(names.length);
for (int i = 0; i < names.length; i++) {
result.add(new Label(names[i], values[i]));
}
return Collections.unmodifiableList(result);
}
/**
* This must not be used in Prometheus exposition formats because names may contain dots.
*
* However, for debugging it's better to show the original names rather than the Prometheus names.
*/
@Override
public String toString() {
StringBuilder b = new StringBuilder();
b.append("{");
for (int i = 0; i < names.length; i++) {
if (i > 0) {
b.append(",");
}
b.append(names[i]);
b.append("=\"");
appendEscapedLabelValue(b, values[i]);
b.append("\"");
}
b.append("}");
return b.toString();
}
private void appendEscapedLabelValue(StringBuilder b, String value) {
for (int i = 0; i < value.length(); i++) {
char c = value.charAt(i);
switch (c) {
case '\\':
b.append("\\\\");
break;
case '\"':
b.append("\\\"");
break;
case '\n':
b.append("\\n");
break;
default:
b.append(c);
}
}
}
@Override
public boolean equals(Object o) {
if (this == o) return true;
if (o == null || getClass() != o.getClass()) return false;
Labels labels = (Labels) o;
return labels.hasSameNames(this) && labels.hasSameValues(this);
}
@Override
public int hashCode() {
int result = Arrays.hashCode(prometheusNames);
result = 31 * result + Arrays.hashCode(values);
return result;
}
public static Builder builder() {
return new Builder();
}
public static class Builder {
private final List names = new ArrayList<>();
private final List values = new ArrayList<>();
private Builder() {
}
/**
* Add a label. Call multiple times to add multiple labels.
*/
public Builder label(String name, String value) {
names.add(name);
values.add(value);
return this;
}
public Labels build() {
return Labels.of(names, values);
}
}
}
