package com.datastax.oss.driver.internal.core.metadata.token;
import com.datastax.oss.driver.api.core.metadata.Node;
import com.datastax.oss.driver.api.core.metadata.token.Token;
import com.datastax.oss.driver.shaded.guava.common.annotations.VisibleForTesting;
import com.datastax.oss.driver.shaded.guava.common.base.Preconditions;
import com.datastax.oss.driver.shaded.guava.common.collect.ImmutableSetMultimap;
import com.datastax.oss.driver.shaded.guava.common.collect.SetMultimap;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
import net.jcip.annotations.ThreadSafe;
@ThreadSafe
class SimpleReplicationStrategy implements ReplicationStrategy {
private final int replicationFactor;
SimpleReplicationStrategy(Map<String, String> replicationConfig) {
this(extractReplicationFactor(replicationConfig));
}
@VisibleForTesting
SimpleReplicationStrategy(int replicationFactor) {
this.replicationFactor = replicationFactor;
}
@Override
public SetMultimap<Token, Node> computeReplicasByToken(
Map<Token, Node> tokenToPrimary, List<Token> ring) {
int rf = Math.min(replicationFactor, ring.size());
ImmutableSetMultimap.Builder<Token, Node> result = ImmutableSetMultimap.builder();
for (int i = 0; i < ring.size(); i++) {
Set<Node> replicas = new LinkedHashSet<>();
for (int j = 0; j < ring.size() && replicas.size() < rf; j++) {
replicas.add(tokenToPrimary.get(getTokenWrapping(i + j, ring)));
}
result.putAll(ring.get(i), replicas);
}
return result.build();
}
private static Token getTokenWrapping(int i, List<Token> ring) {
return ring.get(i % ring.size());
}
private static int (Map<String, String> replicationConfig) {
String factorString = replicationConfig.get("replication_factor");
Preconditions.checkNotNull(factorString, "Missing replication factor in " + replicationConfig);
return Integer.parseInt(factorString);
}
}