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// Copyright Verizon Media. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
package com.yahoo.vespa.hosted.provision.autoscale;
import com.yahoo.config.provision.ClusterSpec;
import com.yahoo.vespa.hosted.provision.Node;
import com.yahoo.vespa.hosted.provision.NodeRepository;
import java.time.Clock;
import java.time.Instant;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Objects;
import java.util.Optional;
import java.util.stream.Collectors;
/**
* An in-memory time-series "database" of node metrics.
* Thread model: One writer, many readers.
*
* @author bratseth
*/
public class NodeMetricsDb {
private final NodeRepository nodeRepository;
/** Measurements by key. Each list of measurements is sorted by increasing timestamp */
private final Map<NodeMeasurementsKey, NodeMeasurements> db = new HashMap<>();
/** Lock all access for now since we modify lists inside a map */
private final Object lock = new Object();
public NodeMetricsDb(NodeRepository nodeRepository) {
this.nodeRepository = nodeRepository;
}
/** Add measurements to this */
public void add(Collection<NodeMetrics.MetricValue> metricValues) {
synchronized (lock) {
for (var value : metricValues) {
Resource resource = Resource.fromMetric(value.name());
NodeMeasurementsKey key = new NodeMeasurementsKey(value.hostname(), resource);
NodeMeasurements measurements = db.get(key);
if (measurements == null) { // new node
Optional<Node> node = nodeRepository.getNode(value.hostname());
if (node.isEmpty()) continue;
if (node.get().allocation().isEmpty()) continue;
measurements = new NodeMeasurements(value.hostname(),
resource,
node.get().allocation().get().membership().cluster().type());
db.put(key, measurements);
}
measurements.add(new Measurement(value.timestampSecond() * 1000,
(float)resource.valueFromMetric(value.value())));
}
}
}
/** Must be called intermittently (as long as add is called) to gc old measurements */
public void gc(Clock clock) {
synchronized (lock) {
// Each measurement is Object + long + float = 16 + 8 + 4 = 28 bytes
// 12 hours with 1k nodes and 3 resources and 1 measurement/sec is about 5Gb
for (Iterator<NodeMeasurements> i = db.values().iterator(); i.hasNext(); ) {
var measurements = i.next();
measurements.removeOlderThan(clock.instant().minus(Autoscaler.scalingWindow(measurements.type)).toEpochMilli());
if (measurements.isEmpty())
i.remove();
}
}
}
/** Returns a window within which we can ask for specific information from this db */
public Window getWindow(Instant startTime, Resource resource, List<String> hostnames) {
return new Window(startTime, resource, hostnames);
}
public class Window {
private final long startTime;
private final List<NodeMeasurementsKey> keys;
private Window(Instant startTime, Resource resource, List<String> hostnames) {
this.startTime = startTime.toEpochMilli();
keys = hostnames.stream().map(hostname -> new NodeMeasurementsKey(hostname, resource)).collect(Collectors.toList());
}
public int measurementCount() {
synchronized (lock) {
int count = 0;
for (NodeMeasurementsKey key : keys) {
NodeMeasurements measurements = db.get(key);
if (measurements == null) continue;
count += measurements.after(startTime).size();
}
return count;
}
}
/** Returns the count of hostnames which have measurements in this window */
public int hostnames() {
synchronized (lock) {
int count = 0;
for (NodeMeasurementsKey key : keys) {
NodeMeasurements measurements = db.get(key);
if (measurements == null || measurements.isEmpty()) continue;
if (measurements.get(measurements.size() - 1).timestamp >= startTime)
count++;
}
return count;
}
}
public double average() {
synchronized (lock) {
double sum = 0;
int count = 0;
for (NodeMeasurementsKey key : keys) {
NodeMeasurements measurements = db.get(key);
if (measurements == null) continue;
int index = measurements.size() - 1;
while (index >= 0 && measurements.get(index).timestamp >= startTime) {
sum += measurements.get(index).value;
count++;
index--;
}
}
return sum / count;
}
}
}
private static class NodeMeasurementsKey {
private final String hostname;
private final Resource resource;
public NodeMeasurementsKey(String hostname, Resource resource) {
this.hostname = hostname;
this.resource = resource;
}
@Override
public int hashCode() {
return Objects.hash(hostname, resource);
}
@Override
public boolean equals(Object o) {
if (this == o) return true;
if ( ! (o instanceof NodeMeasurementsKey)) return false;
NodeMeasurementsKey other = (NodeMeasurementsKey)o;
if ( ! this.hostname.equals(other.hostname)) return false;
if ( ! this.resource.equals(other.resource)) return false;
return true;
}
@Override
public String toString() { return "key to measurements of " + resource + " for " + hostname; }
}
private static class NodeMeasurements {
private final String hostname;
private final Resource resource;
private final ClusterSpec.Type type;
private final List<Measurement> measurements = new ArrayList<>();
public NodeMeasurements(String hostname, Resource resource, ClusterSpec.Type type) {
this.hostname = hostname;
this.resource = resource;
this.type = type;
}
void removeOlderThan(long oldestTimestamp) {
while (!measurements.isEmpty() && measurements.get(0).timestamp < oldestTimestamp)
measurements.remove(0);
}
boolean isEmpty() { return measurements.isEmpty(); }
int size() { return measurements.size(); }
Measurement get(int index) { return measurements.get(index); }
void add(Measurement measurement) { measurements.add(measurement); }
public List<Measurement> after(long oldestTimestamp) {
return measurements.stream()
.filter(measurement -> measurement.timestamp >= oldestTimestamp)
.collect(Collectors.toList());
}
}
private static class Measurement {
/** The time of this measurement in epoch millis */
private final long timestamp;
/** The measured value */
private final float value;
public Measurement(long timestamp, float value) {
this.timestamp = timestamp;
this.value = value;
}
@Override
public String toString() { return "measurement at " + timestamp + ": " + value; }
}
}
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