Add Environment#streamExists(String)

Author: acogoluegnes

src/main/java/com/rabbitmq/stream/Environment.java

@@ -72,6 +72,16 @@ static EnvironmentBuilder builder() {
    */
   StreamStats queryStreamStats(String stream);
 
+  /**
+   * Return whether a stream exists or not.
+   *
+   * @param stream
+   * @return true if stream exists, false if it does not exist
+   * @throws StreamException if response code is different from {@link Constants#RESPONSE_CODE_OK}
+   *     or {@link Constants#RESPONSE_CODE_STREAM_DOES_NOT_EXIST}
+   */
+  boolean streamExists(String stream);
+
   /**
    * Create a {@link ProducerBuilder} to configure and create a {@link Producer}.
    *

src/main/java/com/rabbitmq/stream/impl/StreamEnvironment.java

@@ -17,23 +17,11 @@
 import static com.rabbitmq.stream.impl.Utils.exceptionMessage;
 import static com.rabbitmq.stream.impl.Utils.formatConstant;
 import static com.rabbitmq.stream.impl.Utils.namedRunnable;
+import static java.lang.String.format;
 import static java.util.concurrent.TimeUnit.SECONDS;
 
-import com.rabbitmq.stream.Address;
-import com.rabbitmq.stream.AddressResolver;
-import com.rabbitmq.stream.BackOffDelayPolicy;
-import com.rabbitmq.stream.Codec;
-import com.rabbitmq.stream.ConsumerBuilder;
-import com.rabbitmq.stream.Environment;
-import com.rabbitmq.stream.MessageHandler;
+import com.rabbitmq.stream.*;
 import com.rabbitmq.stream.MessageHandler.Context;
-import com.rabbitmq.stream.NoOffsetException;
-import com.rabbitmq.stream.OffsetSpecification;
-import com.rabbitmq.stream.ProducerBuilder;
-import com.rabbitmq.stream.StreamCreator;
-import com.rabbitmq.stream.StreamException;
-import com.rabbitmq.stream.StreamStats;
-import com.rabbitmq.stream.SubscriptionListener;
 import com.rabbitmq.stream.compression.CompressionCodecFactory;
 import com.rabbitmq.stream.impl.Client.ClientParameters;
 import com.rabbitmq.stream.impl.Client.ShutdownListener;
@@ -515,12 +503,35 @@ public StreamStats queryStreamStats(String stream) {
           response.getResponseCode(),
           stream,
           () ->
-              "Error while querying stream info: "
+              "Error while querying stream stats: "
                   + formatConstant(response.getResponseCode())
                   + ".");
     }
   }
 
+  @Override
+  public boolean streamExists(String stream) {
+    checkNotClosed();
+    this.maybeInitializeLocator();
+    StreamStatsResponse response =
+        locatorOperation(
+            Utils.namedFunction(
+                client -> client.streamStats(stream), "Query stream stats on stream '%s'", stream));
+    if (response.isOk()) {
+      return true;
+    } else if (response.getResponseCode() == Constants.RESPONSE_CODE_STREAM_DOES_NOT_EXIST) {
+      return false;
+    } else {
+      throw convertCodeToException(
+          response.getResponseCode(),
+          stream,
+          () ->
+              format(
+                  "Unexpected result when checking if stream '%s' exists: %s.",
+                  stream, formatConstant(response.getResponseCode())));
+    }
+  }
+
   private static class DefaultStreamStats implements StreamStats {
 
     private final LongSupplier firstOffsetSupplier, committedOffsetSupplier;

src/test/java/com/rabbitmq/stream/impl/StreamEnvironmentTest.java

@@ -559,8 +559,8 @@ void queryStreamStatsShouldReturnFirstOffsetAndCommittedOffset(boolean lazyInit)
       throws Exception {
     try (Environment env = environmentBuilder.lazyInitialization(lazyInit).build()) {
       StreamStats stats = env.queryStreamStats(stream);
-      assertThatThrownBy(() -> stats.firstOffset()).isInstanceOf(NoOffsetException.class);
-      assertThatThrownBy(() -> stats.committedChunkId()).isInstanceOf(NoOffsetException.class);
+      assertThatThrownBy(stats::firstOffset).isInstanceOf(NoOffsetException.class);
+      assertThatThrownBy(stats::committedChunkId).isInstanceOf(NoOffsetException.class);
 
       int publishCount = 20_000;
       TestUtils.publishAndWaitForConfirms(cf, publishCount, stream);
@@ -595,6 +595,16 @@ void queryStreamStatsShouldThrowExceptionWhenStreamDoesNotExist() {
     }
   }
 
+  @ParameterizedTest
+  @ValueSource(booleans = {true, false})
+  @BrokerVersionAtLeast(BrokerVersion.RABBITMQ_3_11)
+  void streamExists(boolean lazyInit) {
+    try (Environment env = environmentBuilder.lazyInitialization(lazyInit).build()) {
+      assertThat(env.streamExists(stream)).isTrue();
+      assertThat(env.streamExists(UUID.randomUUID().toString())).isFalse();
+    }
+  }
+
   @Test
   void methodsShouldThrowExceptionWhenEnvironmentIsClosed() {
     Environment env = environmentBuilder.build();
@@ -605,7 +615,8 @@ void methodsShouldThrowExceptionWhenEnvironmentIsClosed() {
           () -> env.producerBuilder(),
           () -> env.consumerBuilder(),
           () -> env.deleteStream("does not matter"),
-          () -> env.queryStreamStats("does not matter")
+          () -> env.queryStreamStats("does not matter"),
+          () -> env.streamExists("does not matter")
         };
     Arrays.stream(calls)
         .forEach(call -> assertThatThrownBy(call).isInstanceOf(IllegalStateException.class));