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Thread-safety for ResponseContext.REGISTERED_KEYS #9667

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Merged
gianm merged 1 commit into from
Jan 8, 2021
Merged

Thread-safety for ResponseContext.REGISTERED_KEYS #9667

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34 changes: 17 additions & 17 deletions processing/src/main/java/org/apache/druid/query/context/ResponseContext.java
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Original file line number Diff line number Diff line change
Expand Up @@ -25,9 +25,10 @@
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.node.ArrayNode;
import com.fasterxml.jackson.databind.node.ObjectNode;
import com.google.common.base.Preconditions;
import com.google.common.collect.Lists;
import org.apache.druid.guice.annotations.PublicApi;
import org.apache.druid.java.util.common.IAE;
import org.apache.druid.java.util.common.ISE;
import org.apache.druid.java.util.common.NonnullPair;
import org.apache.druid.java.util.common.jackson.JacksonUtils;
import org.apache.druid.query.SegmentDescriptor;
Expand All @@ -41,8 +42,9 @@
import java.util.Comparator;
import java.util.List;
import java.util.Map;
import java.util.TreeMap;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import java.util.concurrent.ConcurrentSkipListMap;
import java.util.function.BiFunction;

/**
Expand Down Expand Up @@ -197,9 +199,11 @@ public enum Key implements BaseKey
);

/**
* TreeMap is used to have the natural ordering of its keys
* ConcurrentSkipListMap is used to have the natural ordering of its keys.
* Thread-safe structure is required since there is no guarantee that {@link #registerKey(BaseKey)}
* would be called only from class static blocks.
*/
private static final Map<String, BaseKey> REGISTERED_KEYS = new TreeMap<>();
private static final ConcurrentMap<String, BaseKey> REGISTERED_KEYS = new ConcurrentSkipListMap<>();

static {
for (BaseKey key : values()) {
Expand All @@ -211,14 +215,11 @@ public enum Key implements BaseKey
* Primary way of registering context keys.
* @throws IllegalArgumentException if the key has already been registered.
*/
public static synchronized void registerKey(BaseKey key)
public static void registerKey(BaseKey key)
{
Preconditions.checkArgument(
!REGISTERED_KEYS.containsKey(key.getName()),
"Key [%s] has already been registered as a context key",
key.getName()
);
REGISTERED_KEYS.put(key.getName(), key);
if (REGISTERED_KEYS.putIfAbsent(key.getName(), key) != null) {
throw new IAE("Key [%s] has already been registered as a context key", key.getName());
}
}

/**
Expand All @@ -227,12 +228,11 @@ public static synchronized void registerKey(BaseKey key)
*/
public static BaseKey keyOf(String name)
{
Preconditions.checkState(
REGISTERED_KEYS.containsKey(name),
"Key [%s] has not yet been registered as a context key",
name
);
return REGISTERED_KEYS.get(name);
BaseKey key = REGISTERED_KEYS.get(name);
if (key == null) {
throw new ISE("Key [%s] has not yet been registered as a context key", name);
}
return key;
}

/**
Expand Down