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Refresh DNS configuration each 5 minutes. (#8468)

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Motivation:

We should refresh the DNS configuration each 5 minutes to be able to detect changes done by the user. This is inline with what OpenJDK is doing

Modifications:

Refresh config every 5 minutes.

Result:

Be able to consume changes made by the user.
This commit is contained in:
Norman Maurer 2018-11-16 10:37:29 +01:00 committed by GitHub
parent ce02d5a184
commit cb0d23923f
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1 changed files with 28 additions and 1 deletions
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29
resolver-dns/src/main/java/io/netty/resolver/dns/DnsServerAddressStreamProviders.java
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@ -18,18 +18,45 @@ package io.netty.resolver.dns;
import io.netty.util.internal.PlatformDependent;
import io.netty.util.internal.UnstableApi;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicLong;
/**
* Utility methods related to {@link DnsServerAddressStreamProvider}.
*/
@UnstableApi
public final class DnsServerAddressStreamProviders {
// We use 5 minutes which is the same as what OpenJDK is using in sun.net.dns.ResolverConfigurationImpl.
private static final long REFRESH_INTERVAL = TimeUnit.MINUTES.toNanos(5);
// TODO(scott): how is this done on Windows? This may require a JNI call to GetNetworkParams
// https://msdn.microsoft.com/en-us/library/aa365968(VS.85).aspx.
private static final DnsServerAddressStreamProvider DEFAULT_DNS_SERVER_ADDRESS_STREAM_PROVIDER =
new DnsServerAddressStreamProvider() {
private volatile DnsServerAddressStreamProvider currentProvider = provider();
private final AtomicLong lastRefresh = new AtomicLong(System.nanoTime());
@Override
public DnsServerAddressStream nameServerAddressStream(String hostname) {
long last = lastRefresh.get();
DnsServerAddressStreamProvider current = currentProvider;
if (System.nanoTime() - last > REFRESH_INTERVAL) {
// This is slightly racy which means it will be possible still use the old configuration for a small
// amount of time, but that's ok.
if (lastRefresh.compareAndSet(last, System.nanoTime())) {
current = currentProvider = provider();
}
}
return current.nameServerAddressStream(hostname);
}
private DnsServerAddressStreamProvider provider() {
// If on windows just use the DefaultDnsServerAddressStreamProvider.INSTANCE as otherwise
// we will log some error which may be confusing.
PlatformDependent.isWindows() ? DefaultDnsServerAddressStreamProvider.INSTANCE :
return PlatformDependent.isWindows() ? DefaultDnsServerAddressStreamProvider.INSTANCE :
UnixResolverDnsServerAddressStreamProvider.parseSilently();
}
};
private DnsServerAddressStreamProviders() {
}