Feat: getNextAliveNode() to failover to alternate endpoints on retryable failures. #2880
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| Original file line number | Diff line number | Diff line change |
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@@ -594,7 +594,10 @@ private ClassicHttpResponse doPostRequest(Map<String, Object> requestConfig, Htt | |
| throw new ClientMisconfigurationException("Proxy authentication required. Please check your proxy settings."); | ||
| } else if (httpResponse.getCode() == HttpStatus.SC_BAD_GATEWAY) { | ||
| httpResponse.close(); | ||
| throw new ConnectException("Server returned '502 Bad gateway'. Check network and proxy settings."); | ||
| } else if (httpResponse.getCode() == HttpStatus.SC_SERVICE_UNAVAILABLE) { | ||
|
Contributor
There was a problem hiding this comment. Please make it a ConnectException. It will be a breaking changes in behavior but we need to fix it because existing behavior is wrong. |
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| httpResponse.close(); | ||
| throw new ConnectException("Server returned '503 Service unavailable'."); | ||
| } else if (httpResponse.getCode() >= HttpStatus.SC_BAD_REQUEST || httpResponse.containsHeader(ClickHouseHttpProto.HEADER_EXCEPTION_CODE)) { | ||
| try { | ||
| throw readError(req, httpResponse); | ||
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,64 @@ | ||
| package com.clickhouse.client.api.transport; | ||
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| import org.slf4j.Logger; | ||
| import org.slf4j.LoggerFactory; | ||
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| import java.util.ArrayList; | ||
| import java.util.Collections; | ||
| import java.util.List; | ||
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| /** | ||
| * So we will look up for the first-alive node and then assign that node to | ||
| * client to talk. | ||
| * | ||
| * <p>Endpoints are tried in the order they were registered (index 0 is the | ||
| * "primary"). When a request fails, the failed endpoint is quarantined for | ||
| * {@link #DEFAULT_QUARANTINE_MS} milliseconds and the next alive endpoint | ||
| * is returned. Once the quarantine expires the node automatically becomes | ||
| * eligible again, so traffic returns to the primary without any explicit | ||
| * reset.</p> | ||
| * | ||
| * <p>If all endpoints are quarantined, the primary (index 0) is returned | ||
| * as a fallback to avoid a complete lockout.</p> | ||
| * | ||
| * <p>This class is thread-safe: concurrent callers may invoke | ||
| * {@link #getEndpoint()} and {@link #getNextAliveNode(Endpoint)} | ||
| * from different threads.</p> | ||
| */ | ||
| public class ClientNodeSelector { | ||
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| private static final Logger LOG = LoggerFactory.getLogger(ClientNodeSelector.class); | ||
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| static final long DEFAULT_QUARANTINE_MS = 30_000; | ||
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| private final List<EndpointState> endpointStates; | ||
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| public ClientNodeSelector(List<Endpoint> endpoints) { | ||
| List<EndpointState> states = new ArrayList<>(endpoints.size()); | ||
| for (Endpoint ep : endpoints) { | ||
| states.add(new EndpointState(ep)); | ||
| } | ||
| this.endpointStates = Collections.unmodifiableList(states); | ||
| } | ||
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| public Endpoint getEndpoint() { | ||
| for (EndpointState state : endpointStates) { | ||
| if (state.isAlive()) { | ||
| return state.getEndpoint(); | ||
| } | ||
| } | ||
| LOG.warn("All endpoints are non-responsive, falling back to primary endpoint"); | ||
| return endpointStates.get(0).getEndpoint(); | ||
| } | ||
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| public Endpoint getNextAliveNode(Endpoint failedEndpoint) { | ||
| for (EndpointState state : endpointStates) { | ||
| if (state.getEndpoint().equals(failedEndpoint)) { | ||
| state.markFailed(DEFAULT_QUARANTINE_MS); | ||
| LOG.warn("Endpoint {} quarantined for {} ms", failedEndpoint.getHost(), DEFAULT_QUARANTINE_MS); | ||
| break; | ||
| } | ||
| } | ||
| return getEndpoint(); | ||
| } | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,33 @@ | ||
| package com.clickhouse.client.api.transport; | ||
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| /** | ||
| *{@link Endpoint} is wrapped to track for failover. | ||
| * When a node fails, it can be quarantined for a fixed duration and after | ||
| * it is expired, it will be considered as alive again. | ||
| */ | ||
| class EndpointState { | ||
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| private final Endpoint endpoint; | ||
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| private volatile long failedUntil; | ||
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| EndpointState(Endpoint endpoint) { | ||
| this.endpoint = endpoint; | ||
| this.failedUntil = 0; | ||
| } | ||
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| Endpoint getEndpoint() { | ||
| return endpoint; | ||
| } | ||
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| void markFailed(long quarantineMs) { | ||
|
Contributor
There was a problem hiding this comment. there should be check for negative and minimal value. |
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| if (quarantineMs <= 0) { | ||
| throw new IllegalArgumentException("Quarantine duration must be positive: " + quarantineMs); | ||
| } | ||
| this.failedUntil = System.currentTimeMillis() + quarantineMs; | ||
| } | ||
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| boolean isAlive() { | ||
| return System.currentTimeMillis() >= failedUntil; | ||
| } | ||
| } | ||
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