feat: Close clients gracefully (#56)

* update

* update

* update

* update

* update

* update

Author: jiangmichaellll

src/main/java/com/google/cloud/pubsublite/spark/PslContinuousReader.java

@@ -98,8 +98,8 @@ public void commit(Offset end) {
 
   @Override
   public void stop() {
-    cursorClient.shutdown();
     committer.close();
+    cursorClient.close();
   }
 
   @Override

src/main/java/com/google/cloud/pubsublite/spark/PslDataSource.java

@@ -16,13 +16,14 @@
 
 package com.google.cloud.pubsublite.spark;
 
+import static com.google.cloud.pubsublite.internal.ExtractStatus.toCanonical;
+
 import com.github.benmanes.caffeine.cache.Ticker;
 import com.google.auto.service.AutoService;
 import com.google.cloud.pubsublite.AdminClient;
 import com.google.cloud.pubsublite.PartitionLookupUtils;
 import com.google.cloud.pubsublite.SubscriptionPath;
 import com.google.cloud.pubsublite.TopicPath;
-import com.google.cloud.pubsublite.internal.CursorClient;
 import java.util.Objects;
 import java.util.Optional;
 import org.apache.spark.sql.sources.DataSourceRegister;
@@ -53,12 +54,13 @@ public ContinuousReader createContinuousReader(
 
     PslDataSourceOptions pslDataSourceOptions =
         PslDataSourceOptions.fromSparkDataSourceOptions(options);
-    CursorClient cursorClient = pslDataSourceOptions.newCursorClient();
-    AdminClient adminClient = pslDataSourceOptions.newAdminClient();
     SubscriptionPath subscriptionPath = pslDataSourceOptions.subscriptionPath();
-    long topicPartitionCount = PartitionLookupUtils.numPartitions(subscriptionPath, adminClient);
+    long topicPartitionCount;
+    try (AdminClient adminClient = pslDataSourceOptions.newAdminClient()) {
+      topicPartitionCount = PartitionLookupUtils.numPartitions(subscriptionPath, adminClient);
+    }
     return new PslContinuousReader(
-        cursorClient,
+        pslDataSourceOptions.newCursorClient(),
         pslDataSourceOptions.newMultiPartitionCommitter(topicPartitionCount),
         pslDataSourceOptions.getSubscriberFactory(),
         subscriptionPath,
@@ -76,19 +78,17 @@ public MicroBatchReader createMicroBatchReader(
 
     PslDataSourceOptions pslDataSourceOptions =
         PslDataSourceOptions.fromSparkDataSourceOptions(options);
-    CursorClient cursorClient = pslDataSourceOptions.newCursorClient();
-    AdminClient adminClient = pslDataSourceOptions.newAdminClient();
     SubscriptionPath subscriptionPath = pslDataSourceOptions.subscriptionPath();
     TopicPath topicPath;
-    try {
+    long topicPartitionCount;
+    try (AdminClient adminClient = pslDataSourceOptions.newAdminClient()) {
       topicPath = TopicPath.parse(adminClient.getSubscription(subscriptionPath).get().getTopic());
+      topicPartitionCount = PartitionLookupUtils.numPartitions(topicPath, adminClient);
     } catch (Throwable t) {
-      throw new IllegalStateException(
-          "Unable to get topic for subscription " + subscriptionPath, t);
+      throw toCanonical(t).underlying;
     }
-    long topicPartitionCount = PartitionLookupUtils.numPartitions(topicPath, adminClient);
     return new PslMicroBatchReader(
-        cursorClient,
+        pslDataSourceOptions.newCursorClient(),
         pslDataSourceOptions.newMultiPartitionCommitter(topicPartitionCount),
         pslDataSourceOptions.getSubscriberFactory(),
         new LimitingHeadOffsetReader(

src/main/java/com/google/cloud/pubsublite/spark/PslMicroBatchInputPartitionReader.java

@@ -97,10 +97,6 @@ public InternalRow get() {
 
   @Override
   public void close() {
-    try {
-      subscriber.close();
-    } catch (Exception e) {
-      log.atWarning().log("Subscriber failed to close.");
-    }
+    subscriber.close();
   }
 }

src/main/java/com/google/cloud/pubsublite/spark/PslMicroBatchReader.java

@@ -115,6 +115,8 @@ public void commit(Offset end) {
   @Override
   public void stop() {
     committer.close();
+    cursorClient.close();
+    headOffsetReader.close();
   }
 
   @Override