Examples with ReplicationThrottler org.apache.druid.server.coordinator.ReplicationThrottler used on opensource projects

Example 1 with ReplicationThrottler

use of org.apache.druid.server.coordinator.ReplicationThrottler in project druid by druid-io.

the class LoadRule method assignReplicasForTier.

/**
 * @param predicate {@link Predicate} used to pre-filter {@link ServerHolder}s retrieved from {@link DruidCluster}.
 */
private int assignReplicasForTier(final String tier, final int targetReplicantsInTier, final int currentReplicantsInTier, final DruidCoordinatorRuntimeParams params, final Predicate<ServerHolder> predicate, final DataSegment segment) {
    final int numToAssign = targetReplicantsInTier - currentReplicantsInTier;
    // if nothing to assign
    if (numToAssign <= 0) {
        return 0;
    }
    String noAvailability = StringUtils.format("No available [%s] servers or node capacity to assign segment[%s]! Expected Replicants[%d]", tier, segment.getId(), targetReplicantsInTier);
    final List<ServerHolder> holders = getFilteredHolders(tier, params.getDruidCluster(), predicate);
    // if no holders available for assignment
    if (holders.isEmpty()) {
        log.warn(noAvailability);
        return 0;
    }
    final ReplicationThrottler throttler = params.getReplicationManager();
    for (int numAssigned = 0; numAssigned < numToAssign; numAssigned++) {
        if (!throttler.canCreateReplicant(tier)) {
            log.info("Throttling replication for segment [%s] in tier [%s]", segment.getId(), tier);
            return numAssigned;
        }
        // Retrieves from cache if available
        ServerHolder holder = strategyCache.remove(tier);
        // Does strategy call if not in cache
        if (holder == null) {
            holder = params.getBalancerStrategy().findNewSegmentHomeReplicator(segment, holders);
        }
        if (holder == null) {
            log.warn(noAvailability);
            return numAssigned;
        }
        holders.remove(holder);
        final SegmentId segmentId = segment.getId();
        final String holderHost = holder.getServer().getHost();
        throttler.registerReplicantCreation(tier, segmentId, holderHost);
        log.info("Assigning 'replica' for segment [%s] to server [%s] in tier [%s]", segment.getId(), holder.getServer().getName(), holder.getServer().getTier());
        holder.getPeon().loadSegment(segment, () -> throttler.unregisterReplicantCreation(tier, segmentId));
    }
    return numToAssign;
}