@@ -0,0 +1,39 @@
+/*
+* Copyright 2020 Google LLC
+*
+* Licensed under the Apache License, Version 2.0 (the "License");
+* you may not use this file except in compliance with the License.
+* You may obtain a copy of the License at
+*
+* http://www.apache.org/licenses/LICENSE-2.0
+*
+* Unless required by applicable law or agreed to in writing, software
+* distributed under the License is distributed on an "AS IS" BASIS,
+* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+* See the License for the specific language governing permissions and
+* limitations under the License.
+*/
+
+package com.google.cloud.spanner;
+
+import com.google.cloud.spanner.SpannerException.ResourceNotFoundException;
+import com.google.rpc.ResourceInfo;
+import javax.annotation.Nullable;
+
+/**
+* Exception thrown by Cloud Spanner when an operation detects that the instance that is being used
+* no longer exists. This type of error has its own subclass as it is a condition that should cause
+* the client library to stop trying to send RPCs to the backend until the user has taken action.
+*/
+public class InstanceNotFoundException extends ResourceNotFoundException {
+private static final long serialVersionUID = 45297002L;
+
+/** Private constructor. Use {@link SpannerExceptionFactory} to create instances. */
+InstanceNotFoundException(
+DoNotConstructDirectly token,
+@Nullable String message,
+ResourceInfo resourceInfo,
+@Nullable Throwable cause) {
+super(token, message, resourceInfo, cause);
+}
+}

@@ -26,6 +26,7 @@
 import com.google.cloud.spanner.Options.QueryOption;
 import com.google.cloud.spanner.Options.ReadOption;
 import com.google.cloud.spanner.SessionClient.SessionConsumer;
+import com.google.cloud.spanner.SpannerException.ResourceNotFoundException;
 import com.google.common.annotations.VisibleForTesting;
 import com.google.common.base.Function;
 import com.google.common.base.MoreObjects;
@@ -781,13 +782,14 @@ public void close() {
 if (lastException != null && isSessionNotFound(lastException)) {
 invalidateSession(this);
 } else {
-if (lastException != null && isDatabaseNotFound(lastException)) {
+if (lastException != null && isDatabaseOrInstanceNotFound(lastException)) {
 // Mark this session pool as no longer valid and then release the session into the pool as
 // there is nothing we can do with it anyways.
 synchronized (lock) {
-SessionPool.this.databaseNotFound =
+SessionPool.this.resourceNotFoundException =
 MoreObjects.firstNonNull(
-SessionPool.this.databaseNotFound, (DatabaseNotFoundException) lastException);
+SessionPool.this.resourceNotFoundException,
+(ResourceNotFoundException) lastException);
 }
 }
 lastException = null;
@@ -1075,7 +1077,7 @@ private static enum Position {
 private SettableFuture<Void> closureFuture;
 
 @GuardedBy("lock")
-private DatabaseNotFoundException databaseNotFound;
+private ResourceNotFoundException resourceNotFoundException;
 
 @GuardedBy("lock")
 private final LinkedList<PooledSession> readSessions = new LinkedList<>();
@@ -1213,8 +1215,8 @@ private boolean isSessionNotFound(SpannerException e) {
 return e.getErrorCode() == ErrorCode.NOT_FOUND && e.getMessage().contains("Session not found");
 }
 
-private boolean isDatabaseNotFound(SpannerException e) {
-return e instanceof DatabaseNotFoundException;
+private boolean isDatabaseOrInstanceNotFound(SpannerException e) {
+return e instanceof DatabaseNotFoundException || e instanceof InstanceNotFoundException;
 }
 
 private boolean isPermissionDenied(SpannerException e) {
@@ -1249,7 +1251,7 @@ private PooledSession findSessionToKeepAlive(
 /** @return true if this {@link SessionPool} is still valid. */
 boolean isValid() {
 synchronized (lock) {
-return closureFuture == null && databaseNotFound == null;
+return closureFuture == null && resourceNotFoundException == null;
 }
 }
 
@@ -1279,14 +1281,14 @@ PooledSession getReadSession() throws SpannerException {
 span.addAnnotation("Pool has been closed");
 throw new IllegalStateException("Pool has been closed");
 }
-if (databaseNotFound != null) {
+if (resourceNotFoundException != null) {
 span.addAnnotation("Database has been deleted");
 throw SpannerExceptionFactory.newSpannerException(
 ErrorCode.NOT_FOUND,
 String.format(
 "The session pool has been invalidated because a previous RPC returned 'Database not found': %s",
-databaseNotFound.getMessage()),
-databaseNotFound);
+resourceNotFoundException.getMessage()),
+resourceNotFoundException);
 }
 sess = readSessions.poll();
 if (sess == null) {
@@ -1344,14 +1346,14 @@ PooledSession getReadWriteSession() {
 span.addAnnotation("Pool has been closed");
 throw new IllegalStateException("Pool has been closed");
 }
-if (databaseNotFound != null) {
+if (resourceNotFoundException != null) {
 span.addAnnotation("Database has been deleted");
 throw SpannerExceptionFactory.newSpannerException(
 ErrorCode.NOT_FOUND,
 String.format(
 "The session pool has been invalidated because a previous RPC returned 'Database not found': %s",
-databaseNotFound.getMessage()),
-databaseNotFound);
+resourceNotFoundException.getMessage()),
+resourceNotFoundException);
 }
 sess = writePreparedSessions.poll();
 if (sess == null) {
@@ -1495,17 +1497,18 @@ private void handleCreateSessionsFailure(SpannerException e, int count) {
 break;
 }
 }
-this.databaseNotFound =
+this.resourceNotFoundException =
 MoreObjects.firstNonNull(
-this.databaseNotFound, isDatabaseNotFound(e) ? (DatabaseNotFoundException) e : null);
+this.resourceNotFoundException,
+isDatabaseOrInstanceNotFound(e) ? (ResourceNotFoundException) e : null);
 }
 }
 
 private void handlePrepareSessionFailure(SpannerException e, PooledSession session) {
 synchronized (lock) {
 if (isSessionNotFound(e)) {
 invalidateSession(session);
-} else if (isDatabaseNotFound(e) || isPermissionDenied(e)) {
+} else if (isDatabaseOrInstanceNotFound(e) || isPermissionDenied(e)) {
 // Database has been deleted or the user has no permission to write to this database. We
 // should stop trying to prepare any transactions. Also propagate the error to all waiters,
 // as any further waiting is pointless.
@@ -1520,10 +1523,10 @@ private void handlePrepareSessionFailure(SpannerException e, PooledSession sessi
 if (isClosed()) {
 decrementPendingClosures(1);
 }
-this.databaseNotFound =
+this.resourceNotFoundException =
 MoreObjects.firstNonNull(
-this.databaseNotFound,
-isDatabaseNotFound(e) ? (DatabaseNotFoundException) e : null);
+this.resourceNotFoundException,
+isDatabaseOrInstanceNotFound(e) ? (ResourceNotFoundException) e : null);
 } else if (readWriteWaiters.size() > 0) {
 releaseSession(session, Position.FIRST);
 readWriteWaiters.poll().put(e);

@@ -42,6 +42,8 @@ public final class SpannerExceptionFactory {
 static final String SESSION_RESOURCE_TYPE = "type.googleapis.com/google.spanner.v1.Session";
 static final String DATABASE_RESOURCE_TYPE =
 "type.googleapis.com/google.spanner.admin.database.v1.Database";
+static final String INSTANCE_RESOURCE_TYPE =
+"type.googleapis.com/google.spanner.admin.instance.v1.Instance";
 private static final Metadata.Key<ResourceInfo> KEY_RESOURCE_INFO =
 ProtoUtils.keyForProto(ResourceInfo.getDefaultInstance());
 
@@ -199,6 +201,8 @@ private static SpannerException newSpannerExceptionPreformatted(
 return new SessionNotFoundException(token, message, resourceInfo, cause);
 } else if (resourceInfo.getResourceType().equals(DATABASE_RESOURCE_TYPE)) {
 return new DatabaseNotFoundException(token, message, resourceInfo, cause);
+} else if (resourceInfo.getResourceType().equals(INSTANCE_RESOURCE_TYPE)) {
+return new InstanceNotFoundException(token, message, resourceInfo, cause);
 }
 }
 // Fall through to the default.