chore: added cleanup option in the setup ListOperationIT (#536)

* chore: added cleanup option in the setup ListOperationIT

* lint

* chore: added try/catch

* chore: reverted project ID

* chore: added filter

* chore: added filter errror

* chore: added sout for deleted items

* chore: removed log message from setup

* chore: added exponential backkoff

* chore: decreased multiplier to 1.1 and setMaxelapsedTime 3min

* chore: added some helpful comments

* chore: lint

samples/snippets/src/test/java/com/example/automl/ListOperationStatusTest.java

@@ -19,9 +19,19 @@
 import static com.google.common.truth.Truth.assertThat;
 import static junit.framework.TestCase.assertNotNull;
 
+import com.google.api.client.util.ExponentialBackOff;
+import com.google.api.gax.rpc.ResourceExhaustedException;
+import com.google.cloud.automl.v1.AutoMlClient;
+import com.google.cloud.automl.v1.LocationName;
+import com.google.longrunning.ListOperationsRequest;
+import com.google.longrunning.Operation;
+import com.google.longrunning.OperationsClient;
 import java.io.ByteArrayOutputStream;
 import java.io.IOException;
 import java.io.PrintStream;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.concurrent.TimeUnit;
 import org.junit.After;
 import org.junit.Before;
 import org.junit.BeforeClass;
@@ -31,7 +41,7 @@
 
 @RunWith(JUnit4.class)
 public class ListOperationStatusTest {
-  private static final String PROJECT_ID = System.getenv("AUTOML_PROJECT_ID");
+  private static final String PROJECT_ID = System.getenv("GOOGLE_CLOUD_PROJECT");
   private ByteArrayOutputStream bout;
   private PrintStream out;
   private PrintStream originalPrintStream;
@@ -49,11 +59,64 @@ public static void checkRequirements() {
   }
 
   @Before
-  public void setUp() {
+  public void setUp() throws IOException, InterruptedException {
     bout = new ByteArrayOutputStream();
     out = new PrintStream(bout);
     originalPrintStream = System.out;
     System.setOut(out);
+
+    // if the LRO status count more than 300, delete half of operations.
+    try (AutoMlClient client = AutoMlClient.create()) {
+      OperationsClient operationsClient = client.getOperationsClient();
+      LocationName projectLocation = LocationName.of(PROJECT_ID, "us-central1");
+      ListOperationsRequest listRequest =
+          ListOperationsRequest.newBuilder().setName(projectLocation.toString()).build();
+      List<String> operationFullPathsToBeDeleted = new ArrayList<>();
+      for (Operation operation : operationsClient.listOperations(listRequest).iterateAll()) {
+        // collect unused operation into the list.
+        // Filter: deleting already done operations.
+        if (operation.getDone() && !operation.hasError()) {
+          operationFullPathsToBeDeleted.add(operation.getName());
+        }
+      }
+
+      if (operationFullPathsToBeDeleted.size() > 300) {
+        System.out.println("Cleaning up...");
+
+
+        for (String operationFullPath :
+            operationFullPathsToBeDeleted.subList(0, operationFullPathsToBeDeleted.size() / 2)) {
+          // retry_interval * (random value in range [1 - rand_factor, 1 + rand_factor])
+          ExponentialBackOff exponentialBackOff = new ExponentialBackOff.Builder()
+              .setInitialIntervalMillis(60000)
+              .setMaxElapsedTimeMillis(300000)
+              .setRandomizationFactor(0.5)
+              .setMultiplier(1.1)
+              .setMaxIntervalMillis(80000)
+              .build();
+
+          // delete unused operations.
+          try {
+            operationsClient.deleteOperation(operationFullPath);
+          } catch (ResourceExhaustedException ex) {
+            // exponential back off and retry.
+            long backOffInMillis = exponentialBackOff.nextBackOffMillis();
+            System.out.printf("Backing off for %d milliseconds "
+                + "due to Resource exhaustion.\n", backOffInMillis);
+            if (backOffInMillis < 0) {
+              break;
+            }
+            System.out.println("Backing off" + backOffInMillis);
+            TimeUnit.MILLISECONDS.sleep(backOffInMillis);
+          } catch (Exception ex) {
+            throw ex;
+          }
+        }
+      } else {
+        // Clear the list since we wont anything with the list.
+        operationFullPathsToBeDeleted.clear();
+      }
+    }
   }
 
   @After