internal:Happy eyeballs (grpc#10731)

* implement happy eyeballs --------- Co-authored-by: tonyjongyoonan <tonyjan@google.com>
larry-safran · Jan 29, 2024 · 7f4c16e · 7f4c16e
1 parent 8e1cc94
commit 7f4c16e
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diff --git a/api/src/main/java/io/grpc/LoadBalancer.java b/api/src/main/java/io/grpc/LoadBalancer.java
@@ -955,6 +955,8 @@ public abstract static class Helper {
      *
      * <p>It must be called from {@link #getSynchronizationContext the Synchronization Context}
      *
+     * @return Must return a valid Subchannel object, may not return null.
+     *
      * @since 1.22.0
      */
     public Subchannel createSubchannel(CreateSubchannelArgs args) {
@@ -1287,7 +1289,8 @@ public void start(SubchannelStateListener listener) {
      */
     public final EquivalentAddressGroup getAddresses() {
       List<EquivalentAddressGroup> groups = getAllAddresses();
-      Preconditions.checkState(groups.size() == 1, "%s does not have exactly one group", groups);
+      Preconditions.checkState(groups != null && groups.size() == 1,
+          "%s does not have exactly one group", groups);
       return groups.get(0);
     }
 

diff --git a/core/src/main/java/io/grpc/internal/GrpcUtil.java b/core/src/main/java/io/grpc/internal/GrpcUtil.java
@@ -24,6 +24,7 @@
 import com.google.common.base.Preconditions;
 import com.google.common.base.Splitter;
 import com.google.common.base.Stopwatch;
+import com.google.common.base.Strings;
 import com.google.common.base.Supplier;
 import com.google.common.util.concurrent.ListenableFuture;
 import com.google.common.util.concurrent.ThreadFactoryBuilder;
@@ -948,5 +949,19 @@ public static String encodeAuthority(String authority) {
     }
   }
 
+  public static boolean getFlag(String envVarName, boolean enableByDefault) {
+    String envVar = System.getenv(envVarName);
+    if (envVar == null) {
+      envVar = System.getProperty(envVarName);
+    }
+    if (enableByDefault) {
+      return Strings.isNullOrEmpty(envVar) || Boolean.parseBoolean(envVar);
+    } else {
+      return !Strings.isNullOrEmpty(envVar) && Boolean.parseBoolean(envVar);
+    }
+  }
+
+
+
   private GrpcUtil() {}
 }