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Use set once for systemd extender #55497

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Merged
merged 4 commits into from
Apr 21, 2020
Merged

Use set once for systemd extender #55497

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b68521f
Use set once for systemd extender
jasontedor Apr 20, 2020
358ee83
Add assertion
jasontedor Apr 20, 2020
c126cbe
Be consistent
jasontedor Apr 20, 2020
cfde1ee
Further consistency
jasontedor Apr 20, 2020
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44 changes: 24 additions & 20 deletions modules/systemd/src/main/java/org/elasticsearch/systemd/SystemdPlugin.java
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Original file line number Diff line number Diff line change
Expand Up @@ -21,6 +21,7 @@

import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.apache.lucene.util.SetOnce;
import org.elasticsearch.Build;
import org.elasticsearch.client.Client;
import org.elasticsearch.cluster.metadata.IndexNameExpressionResolver;
Expand Down Expand Up @@ -79,7 +80,7 @@ public SystemdPlugin() {
enabled = Boolean.TRUE.toString().equals(esSDNotify);
}

Scheduler.Cancellable extender;
final SetOnce<Scheduler.Cancellable> extender = new SetOnce<>();

@Override
public Collection<Object> createComponents(
Expand All @@ -94,24 +95,26 @@ public Collection<Object> createComponents(
final NamedWriteableRegistry namedWriteableRegistry,
final IndexNameExpressionResolver expressionResolver,
final Supplier<RepositoriesService> repositoriesServiceSupplier) {
if (enabled) {
/*
* Since we have set the service type to notify, by default systemd will wait up to sixty seconds for the process to send the
* READY=1 status via sd_notify. Since our startup can take longer than that (e.g., if we are upgrading on-disk metadata) then
* we need to repeatedly notify systemd that we are still starting up by sending EXTEND_TIMEOUT_USEC with an extension to the
* timeout. Therefore, every fifteen seconds we send systemd a message via sd_notify to extend the timeout by thirty seconds.
* We will cancel this scheduled task after we successfully notify systemd that we are ready.
*/
extender = threadPool.scheduleWithFixedDelay(
() -> {
final int rc = sd_notify(0, "EXTEND_TIMEOUT_USEC=30000000");
if (rc < 0) {
logger.warn("extending startup timeout via sd_notify failed with [{}]", rc);
}
},
TimeValue.timeValueSeconds(15),
ThreadPool.Names.SAME);
if (enabled == false) {
extender.set(null);
return List.of();
}
/*
* Since we have set the service type to notify, by default systemd will wait up to sixty seconds for the process to send the
* READY=1 status via sd_notify. Since our startup can take longer than that (e.g., if we are upgrading on-disk metadata) then we
* need to repeatedly notify systemd that we are still starting up by sending EXTEND_TIMEOUT_USEC with an extension to the timeout.
* Therefore, every fifteen seconds we send systemd a message via sd_notify to extend the timeout by thirty seconds. We will cancel
* this scheduled task after we successfully notify systemd that we are ready.
*/
extender.set(threadPool.scheduleWithFixedDelay(
() -> {
final int rc = sd_notify(0, "EXTEND_TIMEOUT_USEC=30000000");
if (rc < 0) {
logger.warn("extending startup timeout via sd_notify failed with [{}]", rc);
}
},
TimeValue.timeValueSeconds(15),
ThreadPool.Names.SAME));
return List.of();
}

Expand All @@ -124,15 +127,16 @@ int sd_notify(@SuppressWarnings("SameParameterValue") final int unset_environmen
@Override
public void onNodeStarted() {
if (enabled == false) {
assert extender.get() == null;
return;
}
final int rc = sd_notify(0, "READY=1");
if (rc < 0) {
// treat failure to notify systemd of readiness as a startup failure
throw new RuntimeException("sd_notify returned error [" + rc + "]");
}
assert extender != null;
final boolean cancelled = extender.cancel();
assert extender.get() != null;
final boolean cancelled = extender.get().cancel();
assert cancelled;
}

Expand Down
12 changes: 6 additions & 6 deletions modules/systemd/src/test/java/org/elasticsearch/systemd/SystemdPluginTests.java
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Original file line number Diff line number Diff line change
Expand Up @@ -63,28 +63,28 @@ public void testIsEnabled() {
final SystemdPlugin plugin = new SystemdPlugin(false, randomPackageBuildType, Boolean.TRUE.toString());
plugin.createComponents(null, null, threadPool, null, null, null, null, null, null, null, null);
assertTrue(plugin.isEnabled());
assertNotNull(plugin.extender);
assertNotNull(plugin.extender.get());
}

public void testIsNotPackageDistribution() {
final SystemdPlugin plugin = new SystemdPlugin(false, randomNonPackageBuildType, Boolean.TRUE.toString());
plugin.createComponents(null, null, threadPool, null, null, null, null, null, null, null, null);
assertFalse(plugin.isEnabled());
assertNull(plugin.extender);
assertNull(plugin.extender.get());
}

public void testIsImplicitlyNotEnabled() {
final SystemdPlugin plugin = new SystemdPlugin(false, randomPackageBuildType, null);
plugin.createComponents(null, null, threadPool, null, null, null, null, null, null, null, null);
assertFalse(plugin.isEnabled());
assertNull(plugin.extender);
assertNull(plugin.extender.get());
}

public void testIsExplicitlyNotEnabled() {
final SystemdPlugin plugin = new SystemdPlugin(false, randomPackageBuildType, Boolean.FALSE.toString());
plugin.createComponents(null, null, threadPool, null, null, null, null, null, null, null, null);
assertFalse(plugin.isEnabled());
assertNull(plugin.extender);
assertNull(plugin.extender.get());
}

public void testInvalid() {
Expand All @@ -102,7 +102,7 @@ public void testOnNodeStartedSuccess() {
randomIntBetween(0, Integer.MAX_VALUE),
(maybe, plugin) -> {
assertThat(maybe, OptionalMatchers.isEmpty());
verify(plugin.extender).cancel();
verify(plugin.extender.get()).cancel();
});
}

Expand Down Expand Up @@ -185,7 +185,7 @@ int sd_notify(final int unset_environment, final String state) {
if (Boolean.TRUE.toString().equals(esSDNotify)) {
assertNotNull(plugin.extender);
} else {
assertNull(plugin.extender);
assertNull(plugin.extender.get());
}

boolean success = false;
Expand Down