Add constants for min, max and init channel count

Author: cindy-peng

google-cloud-datastore/src/main/java/com/google/cloud/datastore/DatastoreOptions.java

@@ -51,6 +51,9 @@ public class DatastoreOptions extends ServiceOptions<Datastore, DatastoreOptions
   private static final String DEFAULT_DATABASE_ID = "";
   public static final String PROJECT_ID_ENV_VAR = "DATASTORE_PROJECT_ID";
   public static final String LOCAL_HOST_ENV_VAR = "DATASTORE_EMULATOR_HOST";
+  public static final int INIT_CHANNEL_COUNT = 1;
+  public static final int MIN_CHANNEL_COUNT = 1;
+  public static final int MAX_CHANNEL_COUNT = 4;
 
   private transient TransportChannelProvider channelProvider = null;
 
@@ -228,8 +231,9 @@ private DatastoreOptions(Builder builder) {
                   DatastoreSettings.defaultGrpcTransportProviderBuilder()
                       .setChannelPoolSettings(
                           ChannelPoolSettings.builder()
-                              .setMinChannelCount(1)
-                              .setMaxChannelCount(4)
+                              .setInitialChannelCount(INIT_CHANNEL_COUNT)
+                              .setMinChannelCount(MIN_CHANNEL_COUNT)
+                              .setMaxChannelCount(MAX_CHANNEL_COUNT)
                               .build()),
                   this);
     }

google-cloud-datastore/src/main/java/com/google/cloud/datastore/spi/v1/GrpcDatastoreRpc.java

@@ -83,8 +83,9 @@ public GrpcDatastoreRpc(DatastoreOptions datastoreOptions) throws IOException {
                   DatastoreSettings.defaultGrpcTransportProviderBuilder()
                       .setChannelPoolSettings(
                           ChannelPoolSettings.builder()
-                              .setMinChannelCount(1)
-                              .setMaxChannelCount(4)
+                              .setInitialChannelCount(DatastoreOptions.INIT_CHANNEL_COUNT)
+                              .setMinChannelCount(DatastoreOptions.MIN_CHANNEL_COUNT)
+                              .setMaxChannelCount(DatastoreOptions.MAX_CHANNEL_COUNT)
                               .build())
                       .build())
               .build();

google-cloud-datastore/src/test/java/com/google/cloud/datastore/DatastoreOptionsTest.java

@@ -117,9 +117,9 @@ public void testGrpcDefaultChannelConfigurations() {
     ChannelPoolSettings channelPoolSettings =
         ((InstantiatingGrpcChannelProvider) datastoreOptions.getTransportChannelProvider())
             .getChannelPoolSettings();
-    assertEquals(channelPoolSettings.getInitialChannelCount(), 1);
-    assertEquals(channelPoolSettings.getMinChannelCount(), 1);
-    assertEquals(channelPoolSettings.getMaxChannelCount(), 4);
+    assertEquals(channelPoolSettings.getInitialChannelCount(), DatastoreOptions.INIT_CHANNEL_COUNT);
+    assertEquals(channelPoolSettings.getMinChannelCount(), DatastoreOptions.MIN_CHANNEL_COUNT);
+    assertEquals(channelPoolSettings.getMaxChannelCount(), DatastoreOptions.MAX_CHANNEL_COUNT);
   }
 
   @Test