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package com.yahoo.search.dispatch;
import com.yahoo.concurrent.Timer;
import com.yahoo.search.Query;
import com.yahoo.vespa.config.search.DispatchConfig;
import static com.yahoo.container.handler.Coverage.DEGRADED_BY_ADAPTIVE_TIMEOUT;
/**
* Computes next timeout based on how many responses has been received so far
*
* @author baldersheim
*/
class AdaptiveTimeoutHandler implements TimeoutHandler {
private final double minimumCoverage;
private final int askedNodes;
private final int minimumResponses;
private final Query query;
private final Timer timer;
private final DispatchConfig config;
private long deadline;
private long adaptiveTimeoutMin;
private long adaptiveTimeoutMax;
boolean adaptiveTimeoutCalculated = false;
AdaptiveTimeoutHandler(Timer timer, DispatchConfig config, int askedNodes, Query query) {
minimumCoverage = config.minSearchCoverage();
this.config = config;
this.askedNodes = askedNodes;
this.query = query;
this.timer = timer;
minimumResponses = (int) Math.ceil(askedNodes * minimumCoverage / 100.0);
deadline = timer.milliTime() + query.getTimeLeft();
}
@Override
public long nextTimeoutMS(int answeredNodes) {
if (askedNodes == answeredNodes) return query.getTimeLeft(); // All nodes have responded - done
if (answeredNodes < minimumResponses) return query.getTimeLeft(); // Minimum responses have not been received yet
if (!adaptiveTimeoutCalculated) {
// Recompute timeout when minimum responses have been received
long timeLeftMs = query.getTimeLeft();
adaptiveTimeoutMin = (long) (timeLeftMs * config.minWaitAfterCoverageFactor());
adaptiveTimeoutMax = (long) (timeLeftMs * config.maxWaitAfterCoverageFactor());
adaptiveTimeoutCalculated = true;
}
long now = timer.milliTime();
int pendingQueries = askedNodes - answeredNodes;
double missWidth = ((100.0 - minimumCoverage) * askedNodes) / 100.0 - 1.0;
double slopedWait = adaptiveTimeoutMin;
if (pendingQueries > 1 && missWidth > 0.0) {
slopedWait += ((adaptiveTimeoutMax - adaptiveTimeoutMin) * (pendingQueries - 1)) / missWidth;
}
long nextAdaptive = (long) slopedWait;
if (nextAdaptive >= deadline - now) {
return deadline - now;
}
deadline = now + nextAdaptive;
return nextAdaptive;
}
@Override
public int reason() {
return DEGRADED_BY_ADAPTIVE_TIMEOUT;
}
}
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