ableegoldman commented on a change in pull request #10683:
URL: https://github.com/apache/kafka/pull/10683#discussion_r669210507
##########
File path:
streams/src/main/java/org/apache/kafka/streams/processor/internals/TopologyMetadata.java
##########
@@ -16,10 +16,294 @@
*/
package org.apache.kafka.streams.processor.internals;
+import org.apache.kafka.clients.consumer.OffsetResetStrategy;
+import org.apache.kafka.common.TopicPartition;
+import org.apache.kafka.streams.StreamsConfig;
+import org.apache.kafka.streams.errors.TopologyException;
+import org.apache.kafka.streams.processor.StateStore;
+import org.apache.kafka.streams.processor.TaskId;
+import
org.apache.kafka.streams.processor.internals.InternalTopologyBuilder.TopicsInfo;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
import java.util.Objects;
+import java.util.Set;
+import java.util.SortedMap;
+import java.util.TreeMap;
+import java.util.function.Consumer;
+import java.util.function.Function;
+import java.util.regex.Pattern;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+// TODO KAFKA-12648:
+// 1) synchronize on these methods instead of individual
InternalTopologyBuilder methods, where applicable
public class TopologyMetadata {
- //TODO KAFKA-12648: the TopologyMetadata class is filled in by Pt. 2 (PR
#10683)
+ private final Logger log = LoggerFactory.getLogger(TopologyMetadata.class);
+
+ // the '_' character is not allowed for topology names, thus it's safe to
use to indicate that it's not a named topology
+ private static final String UNNAMED_TOPOLOGY = "__UNNAMED_TOPOLOGY__";
+ private static final Pattern EMPTY_ZERO_LENGTH_PATTERN =
Pattern.compile("");
+
+ private final StreamsConfig config;
+ private final SortedMap<String, InternalTopologyBuilder> builders; // Keep
sorted by topology name for readability
+
+ private ProcessorTopology globalTopology;
+ private Map<String, StateStore> globalStateStores = new HashMap<>();
+ final Set<String> allInputTopics = new HashSet<>();
+
+ public TopologyMetadata(final InternalTopologyBuilder builder, final
StreamsConfig config) {
+ this.config = config;
+ builders = new TreeMap<>();
+ if (builder.hasNamedTopology()) {
+ builders.put(builder.namedTopology(), builder);
+ } else {
+ builders.put(UNNAMED_TOPOLOGY, builder);
+ }
+ }
+
+ public TopologyMetadata(final SortedMap<String, InternalTopologyBuilder>
builders, final StreamsConfig config) {
+ this.config = config;
+ this.builders = builders;
+ if (builders.isEmpty()) {
+ log.debug("Building KafkaStreams app with no empty topology");
+ }
+ }
+
+ public int getNumStreamThreads(final StreamsConfig config) {
+ final int configuredNumStreamThreads =
config.getInt(StreamsConfig.NUM_STREAM_THREADS_CONFIG);
+
+ // If the application uses named topologies, it's possible to start up
with no topologies at all and only add them later
+ if (builders.isEmpty()) {
+ if (configuredNumStreamThreads != 0) {
+ log.info("Overriding number of StreamThreads to zero for empty
topology");
+ }
+ return 0;
+ }
+
+ // If there are topologies but they are all empty, this indicates a
bug in user code
+ if (hasNoNonGlobalTopology() && !hasGlobalTopology()) {
Review comment:
Sure, but if `builders.isEmpty` then we would enter the `if` block above
and return before reaching this section of the code. But I think maybe you
meant that in `hasNoNonGlobalTopology`, we should actually return true only if
_all_ builders have no non-global topology, not if that's true for _any one_ of
them? There's some argument to be made for how to handle the case where some
named topologies are legit, while others are empty, but I would still advocate
for throwing an exception when _any_ topology is empty since this is not a
valid configuration. In which case, the current code is correct, but the
comment is not. I'll fix the misleading comment
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