FANNG1 commented on code in PR #8602:
URL: https://github.com/apache/gravitino/pull/8602#discussion_r2365105561
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core/src/main/java/org/apache/gravitino/metrics/MetricsSystem.java:
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@@ -147,34 +147,50 @@ public void close() {
});
}
- /*
- * Extract a metric name and labels from Dropwizard metrics for Prometheus.
+ /**
+ * Provides rules to extract a metric name and labels from Dropwizard
metrics for Prometheus.
*
- * All extraction rules must be registered with the Prometheus registry
before starting the Prometheus
- * servlet. At times, certain MetricsSources, like HiveCatalogMetricsSource,
may not register with
- * MetricsSystem. Therefore, all rules are consolidated in MetricsSystem
instead of being spread across
- * separate MetricsSources.
+ * <p>All extraction rules must be registered with the Prometheus registry
before starting the
+ * Prometheus servlet. At times, certain MetricsSources, like
HiveCatalogMetricsSource, may not
+ * register with MetricsSystem. Therefore, all rules are consolidated in
MetricsSystem instead of
+ * being spread across separate MetricsSources.
*
- * If a metric name doesn't match any rules, it will be converted to the
Prometheus metrics
+ * <p>If a metric name doesn't match any rules, it will be converted to the
Prometheus metrics
* name format. For example, "ab.c-a.d" transforms into "ab_c_a_d".
*
- * The MapperConfig is utilized to extract Prometheus metricsName and labels
with the following method:
- * `MapperConfig(final String match, final String name, final Map<String,
String> labels)`
- * - `match` is a regex used to match the incoming metric name. It employs a
simplified glob syntax where
- * only '*' is allowed.
- * - `name` is the new metric name, which can contain placeholders to be
replaced with
- * actual values from the incoming metric name. Placeholders are in the
${n} format, where n
- * is the zero-based index of the group to extract from the original
metric name.
- * - `labels` are the labels to be extracted, and they should also contain
placeholders.
- * E.g.:
+ * <p>The {@link MapperConfig} is utilized to extract Prometheus metric
names and labels. The
+ * constructor is {@code MapperConfig(final String match, final String name,
final Map<String,
+ * String> labels)}:
+ *
+ * <ul>
+ * <li>{@code match}: A regex used to match the incoming metric name. It
employs a simplified
+ * glob syntax where only '*' is allowed.
+ * <li>{@code name}: The new metric name, which can contain placeholders
to be replaced with
+ * actual values from the incoming metric name. Placeholders are in
the {@code ${n}} format,
+ * where n is the zero-based index of the group to extract from the
original metric name.
+ * <li>{@code labels}: The labels to be extracted, which can also contain
placeholders.
+ * </ul>
+ *
+ * <p>Example:
+ *
+ * <pre>{@code
* Match: gravitino.dispatcher.*.*
* Name: dispatcher_events_total_${0}
- * Labels: label1: ${1}_t
+ * Labels: {label1: "${1}_t"}
+ * }</pre>
+ *
* A metric "gravitino.dispatcher.sp1.yay" will be converted to a new metric
with name
- * "dispatcher_events_total_sp1" with label {label1: yay_t}.
- * Metric names MUST adhere to the regex [a-zA-Z_:]([a-zA-Z0-9_:])*.
- * Label names MUST adhere to the regex [a-zA-Z_]([a-zA-Z0-9_])*.
- * Label values MAY be any sequence of UTF-8 characters .
+ * "dispatcher_events_total_sp1" and label {@code {label1="yay_t"}}.
+ *
+ * <p>Constraints for Prometheus metrics:
+ *
+ * <ul>
+ * <li>Metric names MUST adhere to the regex {@code
[a-zA-Z_:][a-zA-Z0-9_:]*}.
+ * <li>Label names MUST adhere to the regex {@code [a-zA-Z_][a-zA-Z0-9_]*}.
+ * <li>Label values MAY be any sequence of UTF-8 characters.
+ * </ul>
+ *
+ * @return A list of {@link MapperConfig} rules.
*/
@VisibleForTesting
static List<MapperConfig> getMetricNameAndLabelRules() {
Review Comment:
could you add test for it?
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