fix failover

common/lib/host_list_provider/rds_host_list_provider.ts

@@ -145,7 +145,7 @@ export class RdsHostListProvider implements DynamicHostListProvider {
     if (client) {
       return await dialect.getHostRole(client);
     } else {
-      throw new AwsWrapperError(Messages.get("AwsClient targetClient not defined."));
+      throw new AwsWrapperError(Messages.get("AwsClient.targetClientNotDefined"));
     }
   }
 

common/lib/plugins/failover/failover_plugin.ts

@@ -393,7 +393,7 @@ export class FailoverPlugin extends AbstractConnectionPlugin {
           await this.pluginService.setCurrentClient(result.client, result.newHost);
           this.pluginService.getCurrentHostInfo()?.removeAlias(Array.from(oldAliases));
           await this.updateTopology(true);
-          this.failoverReaderSuccessCounter.inc();
+          await this.throwFailoverSuccessError();
         } catch (error: any) {
           this.failoverReaderFailedCounter.inc();
           throw error;
@@ -406,6 +406,21 @@ export class FailoverPlugin extends AbstractConnectionPlugin {
     }
   }
 
+  async throwFailoverSuccessError() {
+    if (this._isInTransaction || this.pluginService.isInTransaction()) {
+      this.pluginService.setInTransaction(false);
+
+      // "Transaction resolution unknown. Please re-configure session state if required and try
+      // restarting transaction."
+      logger.debug(Messages.get("Failover.transactionResolutionUnknownError"));
+      throw new TransactionResolutionUnknownError(Messages.get("Failover.transactionResolutionUnknownError"));
+    } else {
+      // "The active SQL connection has changed due to a connection failure. Please re-configure
+      // session state if required."
+      throw new FailoverSuccessError(Messages.get("Failover.connectionChangedError"));
+    }
+  }
+
   async failoverWriter() {
     logger.debug(Messages.get("Failover.startWriterFailover"));
 
@@ -440,7 +455,7 @@ export class FailoverPlugin extends AbstractConnectionPlugin {
           await this.pluginService.setCurrentClient(result.client, writerHostInfo);
           logger.debug(Messages.get("Failover.establishedConnection", this.pluginService.getCurrentHostInfo()?.host ?? ""));
           await this.pluginService.refreshHostList();
-          this.failoverWriterSuccessCounter.inc();
+          await this.throwFailoverSuccessError();
         } catch (error: any) {
           this.failoverWriterFailedCounter.inc();
           throw error;

common/lib/plugins/failover/reader_failover_handler.ts

@@ -113,23 +113,14 @@ export class ClusterAwareReaderFailoverHandler implements ReaderFailoverHandler
         // ensure new connection is to a reader host
         await this.pluginService.refreshHostList();
         const topology = this.pluginService.getHosts();
-
-        for (let i = 0; i < topology.length; i++) {
-          const host = topology[i];
-          if (host.host === result.newHost.host) {
-            // found new connection host in the latest topology
-            if (host.role === HostRole.READER) {
-              return result;
-            }
+        try {
+          if ((await this.pluginService.getHostRole(result.client)) !== HostRole.READER) {
+            return result;
           }
+        } catch (error) {
+          logger.debug(Messages.get("ClusterAwareReaderFailoverHandler.errorGettingHostRole", error.message));
         }
 
-        // New host is not found in the latest topology. There are few possible reasons for that.
-        // - Host is not yet presented in the topology due to failover process in progress
-        // - Host is in the topology but its role isn't a
-        //   READER (that is not acceptable option due to this.strictReader setting)
-        // Need to continue this loop and to make another try to connect to a reader.
-
         try {
           await this.pluginService.abortTargetClient(result.client);
         } catch (error) {
@@ -276,7 +267,9 @@ export class ClusterAwareReaderFailoverHandler implements ReaderFailoverHandler
 
     const hostsByPriority: HostInfo[] = [...activeReaders];
     const numReaders: number = activeReaders.length + downHostList.length;
-    if (writerHost && (!this.enableFailoverStrictReader || numReaders === 0)) {
+    // Since the writer instance may change during failover, the original writer is likely now a reader. We will include
+    // it and then verify the role once connected if using "strict-reader".
+    if (writerHost || numReaders === 0) {
       hostsByPriority.push(writerHost);
     }
     hostsByPriority.push(...downHostList);
@@ -325,13 +318,8 @@ class ConnectionAttemptTask {
 
       // ensure that new connection is a connection to a reader node
       try {
-        // eslint-disable-next-line no-constant-condition
-        while (1) {
-          await this.pluginService.forceRefreshHostList();
-          if ((await this.pluginService.getHostRole(this.targetClient)) === HostRole.READER) {
-            break;
-          }
-          await sleep(1000);
+        if ((await this.pluginService.getHostRole(this.targetClient)) === HostRole.READER) {
+          return this.targetClient;
         }
       } catch (error: any) {
         logger.debug(Messages.get("ClusterAwareReaderFailoverHandler.errorGettingHostRole", error.message));

common/lib/utils/locales/en.json

@@ -48,7 +48,7 @@
   "ClusterAwareWriterFailoverHandler.standaloneHost": "[TaskB] Host %s is not yet connected to a cluster. The cluster is still being reconfigured.",
   "ClusterAwareWriterFailoverHandler.taskBAttemptConnectionToNewWriter": "[TaskB] Trying to connect to a new writer: '%s'",
   "ClusterAwareWriterFailoverHandler.alreadyWriter": "Current reader connection is actually a new writer connection.",
-  "ClusterAwareReaderFailoverHandler.errorGettingHostRole": "An error occurred while trying to determine the role of the reader candidate: ",
+  "ClusterAwareReaderFailoverHandler.errorGettingHostRole": "An error occurred while trying to determine the role of the reader candidate: %s.",
   "Failover.TransactionResolutionUnknownError": "Transaction resolution unknown. Please re-configure session state if required and try restarting the transaction.",
   "Failover.connectionChangedError": "The active SQL connection has changed due to a connection failure. Please re-configure session state if required.",
   "Failover.parameterValue": "%s = %s",
@@ -195,5 +195,5 @@
   "ConfigurationProfileBuilder.profileNameRequired": "Profile name is required.",
   "ConfigurationProfileBuilder.canNotUpdateKnownPreset": "Can't add or update a built-in preset configuration profile '%s'.",
   "AwsClient.configurationProfileNotFound": "Configuration profile '%s' not found.",
-  "AwsClient targetClient not defined.": "AwsClient targetClient not defined."
+  "AwsClient.targetClientNotDefined": "AwsClient targetClient not defined."
 }