Remove global SHARED_RESOURCE_CHANNELS.

s2a/src/main/java/io/grpc/s2a/channel/S2AHandshakerServiceChannel.java

@@ -20,7 +20,6 @@
 import static java.util.concurrent.TimeUnit.SECONDS;
 
 import com.google.common.annotations.VisibleForTesting;
-import com.google.common.collect.Maps;
 import io.grpc.CallOptions;
 import io.grpc.Channel;
 import io.grpc.ChannelCredentials;
@@ -35,14 +34,13 @@
 import io.netty.util.concurrent.DefaultThreadFactory;
 import java.time.Duration;
 import java.util.Optional;
-import java.util.concurrent.ConcurrentMap;
 import javax.annotation.concurrent.ThreadSafe;
 
 /**
- * Provides APIs for managing gRPC channels to S2A servers. Each channel is local and plaintext. If
- * credentials are provided, they are used to secure the channel.
+ * Provides APIs for managing gRPC channels to an S2A server. Each channel is local and plaintext.
+ * If credentials are provided, they are used to secure the channel.
  *
- * <p>This is done as follows: for each S2A server, provides an implementation of gRPC's {@link
+ * <p>This is done as follows: for an S2A server, provides an implementation of gRPC's {@link
  * SharedResourceHolder.Resource} interface called a {@code Resource<Channel>}. A {@code
  * Resource<Channel>} is a factory for creating gRPC channels to the S2A server at a given address,
  * and a channel must be returned to the {@code Resource<Channel>} when it is no longer needed.
@@ -59,8 +57,6 @@
  */
 @ThreadSafe
 public final class S2AHandshakerServiceChannel {
-  private static final ConcurrentMap<String, Resource<Channel>> SHARED_RESOURCE_CHANNELS =
-      Maps.newConcurrentMap();
   private static final Duration DELEGATE_TERMINATION_TIMEOUT = Duration.ofSeconds(2);
   private static final Duration CHANNEL_SHUTDOWN_TIMEOUT = Duration.ofSeconds(10);
 
@@ -76,8 +72,7 @@ public final class S2AHandshakerServiceChannel {
   public static Resource<Channel> getChannelResource(
       String s2aAddress, Optional<ChannelCredentials> s2aChannelCredentials) {
     checkNotNull(s2aAddress);
-    return SHARED_RESOURCE_CHANNELS.computeIfAbsent(
-        s2aAddress, channelResource -> new ChannelResource(s2aAddress, s2aChannelCredentials));
+    return new ChannelResource(s2aAddress, s2aChannelCredentials);
   }
 
   /**

s2a/src/test/java/io/grpc/s2a/channel/S2AHandshakerServiceChannelTest.java

@@ -97,10 +97,10 @@ public void getChannelResource_mtlsSuccess() throws Exception {
 
   /**
    * Creates two {@code Resoure<Channel>}s for the same target address and verifies that they are
-   * equal.
+   * distinct.
    */
   @Test
-  public void getChannelResource_twoEqualChannels() {
+  public void getChannelResource_twoUnEqualChannels() {
     Resource<Channel> resource =
         S2AHandshakerServiceChannel.getChannelResource(
             "localhost:" + plaintextServer.getPort(),
@@ -109,19 +109,19 @@ public void getChannelResource_twoEqualChannels() {
         S2AHandshakerServiceChannel.getChannelResource(
             "localhost:" + plaintextServer.getPort(),
             /* s2aChannelCredentials= */ Optional.empty());
-    assertThat(resource).isEqualTo(resourceTwo);
+    assertThat(resource).isNotEqualTo(resourceTwo);
   }
 
   /** Same as getChannelResource_twoEqualChannels, but use mTLS. */
   @Test
-  public void getChannelResource_mtlsTwoEqualChannels() throws Exception {
+  public void getChannelResource_mtlsTwoUnEqualChannels() throws Exception {
     Resource<Channel> resource =
         S2AHandshakerServiceChannel.getChannelResource(
             "localhost:" + mtlsServer.getPort(), getTlsChannelCredentials());
     Resource<Channel> resourceTwo =
         S2AHandshakerServiceChannel.getChannelResource(
             "localhost:" + mtlsServer.getPort(), getTlsChannelCredentials());
-    assertThat(resource).isEqualTo(resourceTwo);
+    assertThat(resource).isNotEqualTo(resourceTwo);
   }
 
   /**