lianetm commented on code in PR #21080:
URL: https://github.com/apache/kafka/pull/21080#discussion_r3574183327
##########
clients/src/main/java/org/apache/kafka/clients/NetworkClient.java:
##########
@@ -1210,6 +1280,137 @@ private boolean isTelemetryApi(ApiKeys apiKey) {
return apiKey == ApiKeys.GET_TELEMETRY_SUBSCRIPTIONS || apiKey ==
ApiKeys.PUSH_TELEMETRY;
}
+ public static class BootstrapConfiguration {
+ public static final BootstrapConfiguration DISABLED =
+ new BootstrapConfiguration(List.of(), null, 0, 0);
+
+ public final List<String> bootstrapServers;
+ public final ClientDnsLookup clientDnsLookup;
+ public final long bootstrapResolveTimeoutMs;
+ public final long retryBackoffMs;
+
+ private BootstrapConfiguration(final List<String> bootstrapServers,
+ final ClientDnsLookup clientDnsLookup,
+ final long bootstrapResolveTimeoutMs,
+ final long retryBackoffMs) {
+ this.bootstrapServers = bootstrapServers;
+ this.clientDnsLookup = clientDnsLookup;
+ this.bootstrapResolveTimeoutMs = bootstrapResolveTimeoutMs;
+ this.retryBackoffMs = retryBackoffMs;
+ }
+
+ public static BootstrapConfiguration enabled(final List<String>
bootstrapServers,
+ final ClientDnsLookup
clientDnsLookup,
+ final long
bootstrapResolveTimeoutMs,
+ final long
retryBackoffMs) {
+ for (String url : bootstrapServers) {
+ if (Utils.getHost(url) == null || Utils.getPort(url) == null)
+ throw new ConfigException("Invalid url in " +
CommonClientConfigs.BOOTSTRAP_SERVERS_CONFIG + ": " + url);
+ }
+ return new BootstrapConfiguration(bootstrapServers,
clientDnsLookup, bootstrapResolveTimeoutMs, retryBackoffMs);
+ }
+ }
+
+ /**
+ * Attempts to resolve bootstrap server addresses via DNS and create an
initial bootstrap cluster.
+ * This method is called from {@link #poll(long, long)} and uses a truly
asynchronous approach
+ * to avoid blocking on DNS resolution.
+ *
+ * <p>DNS resolution is performed on a separate thread via {@link
CompletableFuture}. This ensures
+ * the event loop remains responsive even if DNS lookups block or take a
long time. The bootstrap
+ * timeout can interrupt a pending DNS resolution, unlike synchronous
approaches.
+ *
+ * @param currentTimeMs The current time in milliseconds
+ * @throws BootstrapResolutionException if the bootstrap timeout expires
before DNS resolution succeeds
+ */
+ void ensureBootstrapped(final long currentTimeMs) {
+ if (bootstrapConfiguration == BootstrapConfiguration.DISABLED ||
metadataUpdater.isBootstrapped())
+ return;
+
+ if (bootstrapException != null)
+ return;
+
+ if (Thread.interrupted()) {
+ cancelBootstrapResolution();
+ throw new InterruptException(new InterruptedException());
+ }
+
+ // Check if a pending resolution completed before checking the
timeout, so that a
+ // result arriving at the same time as the deadline is not incorrectly
rejected.
+ if (pendingBootstrapResolution != null &&
pendingBootstrapResolution.isDone()) {
+ processBootstrapResolutionResult(currentTimeMs);
+ if (metadataUpdater.isBootstrapped())
+ return;
+ }
+
+ maybeStartBootstrapResolution(currentTimeMs);
Review Comment:
do we have a test to cover this timeout=0 behaviour? let's add it if not
present, seems something that could easily break we a simple
reorder/refactoring of this flow.
##########
clients/src/main/java/org/apache/kafka/clients/CommonClientConfigs.java:
##########
@@ -60,6 +60,12 @@ public class CommonClientConfigs {
+ "resolve each
bootstrap address into a list of canonical names. After "
+ "the bootstrap phase,
this behaves the same as <code>use_all_dns_ips</code>.";
+ public static final String BOOTSTRAP_RESOLVE_TIMEOUT_MS_CONFIG =
"bootstrap.resolve.timeout.ms";
+ public static final long DEFAULT_BOOTSTRAP_RESOLVE_TIMEOUT_MS = 2 * 60 *
1000L;
+ public static final String BOOTSTRAP_RESOLVE_TIMEOUT_MS_DOC = "Maximum
amount of time clients can spend trying to" +
+ " resolve for the bootstrap server address. If the resolution cannot
be completed within this timeframe, a " +
+ "<code>BootstrapResolutionException</code> will be thrown.";
Review Comment:
should we clarify the timeout=0 behaviour after the latest changes? (mention
that 0 means the client attempts resolution once and fails with
BootstrapException if not immediately resolved etc)
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