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IDIEP-114
Author
 Vladimir Steshin 
Sponsor

Nikita Amelchev 

Created
Status

Status
colourGrey
titleDRAFT


Table of Contents

Motivation

...

  • Custom metrics affect performance and take additional resources.
  • There could be race conditions on metric registrations. Metrics with incompatible types can be concurrently registered with the same names.
  • We do not expose API of all internal metrics. At least with the first tickets.
  • Custom metrics aren't stored and require re-registration after node restart. At least with the first tickets.

API

To give an user the ability to register additional metrics, we could either:

  • Refactor a bit our current metrics. Create interfaces for writable metric registry, metric manager. Create interfaces for metrics like int, double, long, longAdder, boolean, object and the gauge metrics (IntGauge, LongGauge, etc.).
  • Provide tiny-enough facade with consumers and suppliers for int, long, double value metrics.

These two approaches are shown below.

The APIs are supposed to be experimental.

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Interfaces for existing metrics

Code Block
languagejava
package org.apache.ignite.metric;

public interface IgniteMetrics extends Iterable<ReadOnlyMetricRegistry> {
    MetricRegistry customRegistry(String registryName);
    @Nullable ReadOnlyMetricRegistry findRegistry(String registryName);
    void removeCustomRegistry(String registryName);
}

...

Code Block
languagejava
package org.apache.ignite.metric;

public interface ObjectValueMetric<T> extends ObjectMetric<T> {
    void value(T value);
}

public interface DoubleValueMetric extends DoubleMetric {
    void add(double value);
    void value(double value);
}

public interface LongSumMetric extends LongMetric {
    void add(long value);
    void increment();
    void decrement();
}

public interface LongValueMetric extends LongSumMetric {
    void value(long value);
}

API alternative: single minimal facade

Instead of the interfeces set above, we could bring only a minimal metric management interface.

Code Block
languagejava
package org.apache.ignite;

public interface IgniteMetrics extends Iterable<ReadOnlyMetricRegistry> {
    LongConsumer longMetric(String registryName, String metricName, @Nullable String description);
    DoubleConsumer doubleMetric(String registryName, String metricName, @Nullable String description);
    IntConsumer booleanMetric(String registryName, String metricName, @Nullable String description);
    void longMetric(String registryName, String metricName, LongSupplier supplier, @Nullable String description);
    void doubleMetric(String registryName, String metricName, DoubleSupplier supplier, @Nullable String description);
    void intMetric(String registryName, String metricName, BooleanSupplier supplier, @Nullable String description);
    void removeCustomMetric(String registryName, String metricName);
    void removeCustomRegistry(String registryName);
    @Nullable ReadOnlyMetricRegistry findRegistry(String registryName);
}

Code examples

Expand
titleCustom metric within a service

/** */
public static final class TestCustomMetricsService implements TestService {
    /** */
    @IgniteInstanceResource
    private Ignite ignite;

    /** */
    @ServiceContextResource
    private ServiceContext ctx;

    /** */
    private AtomicReference<UUID> remoteId;

    /** */
    private final AtomicInteger metricValue = new AtomicInteger();

    /** {@inheritDoc} */
    @Override public void init() throws Exception {
        remoteId = new AtomicReference<>();
          

        // Registers metric "custom.service.svc.filteredInvocation"

        ignite.metrics().customRegistry(regName(ctx.name())).gauge("filteredInvocation", metricValue::get, "Counter of speceific service invocation.");

        // Registers metric "custom.service.svc.loaded"
        ignite.metrics().customRegistry(regName(ctx.name())).gauge("loaded", () -> metricValue.get() >= 100, "Load flag.");

        // Registers metric "custom.service.svc.remote.classId"
        ignite.metrics().customRegistry(regName(ctx.name())).gauge("remote.classId", () -> remoteId.get(), UUID.class, "Remote system class id.");
    }

    /** {@inheritDoc} */
    @Override public void cancel() {
        refresh();

        ignite.metrics().customRegistry(regName(ctx.name())).remove(COUNTER_METRIC_NAME);
    }

    /** {@inheritDoc} */
    @Override public void refresh() {
        metricValue.set(0);

        remoteId.set(null);
    }

    /** */
    @Override public void invoke(int param) {
        if (ctx.isCancelled())
            return;

        remoteId.compareAndSet(null, UUID.randomUUID());

        // Updates metric sometimes.
        if (!ctx.isCancelled() && param % 10 == 0)
            metricValue.set(param / 10);
    }

    /** */
    private static String regName(String svcName) {
        return "service." + svcName;
    }
}

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