fix: reader failover wait for completed batch

Author: crystall-bitquill

common/lib/plugins/failover/reader_failover_handler.ts

@@ -152,13 +152,9 @@ export class ClusterAwareReaderFailoverHandler implements ReaderFailoverHandler
           return result;
         }
       } catch (error) {
-        if (error instanceof AggregateError && error.message.includes("All promises were rejected")) {
-          // ignore and try the next batch
-        } else {
-          // Failover has failed.
-          this.taskHandler.setSelectedConnectionAttemptTask(failoverTaskId, ClusterAwareReaderFailoverHandler.FAILOVER_FAILED);
-          throw error;
-        }
+        // Failover has failed.
+        this.taskHandler.setSelectedConnectionAttemptTask(failoverTaskId, ClusterAwareReaderFailoverHandler.FAILOVER_FAILED);
+        throw error;
       }
 
       await sleep(1000);
@@ -184,7 +180,7 @@ export class ClusterAwareReaderFailoverHandler implements ReaderFailoverHandler
         throw new AwsWrapperError("Connection attempt task timed out.");
       })
       .catch((error) => {
-        if (error instanceof InternalQueryTimeoutError || (error instanceof AggregateError && error.message.includes("All promises were rejected"))) {
+        if (error instanceof InternalQueryTimeoutError) {
           // ignore so the next task batch can be attempted
           return ClusterAwareReaderFailoverHandler.FAILED_READER_FAILOVER_RESULT;
         }
@@ -207,7 +203,26 @@ export class ClusterAwareReaderFailoverHandler implements ReaderFailoverHandler
       tasks.push(secondTask.call());
     }
 
-    return await Promise.any(tasks);
+    return await Promise.any(tasks).catch((error: AggregateError) => {
+      let errors: string = "";
+      for (const e of error.errors) {
+        // Propagate errors that are not caused by network errors.
+        if (!this.pluginService.isNetworkError(error)) {
+          errors += `\n\t${e} - ${e.message}`;
+        }
+      }
+      if (errors) {
+        const awsWrapperError = new AwsWrapperError(
+          Messages.get(
+            "ClusterAwareReaderFailoverHandler.batchFailed",
+            `[${hosts[i].hostId}${numTasks === 2 ? `, ${hosts[i + 1].hostId}` : ``}]`,
+            `[\n${errors}\n]`
+          )
+        );
+        return new ReaderFailoverResult(null, null, false, awsWrapperError);
+      }
+      return new ReaderFailoverResult(null, null, false, undefined);
+    });
   }
 
   getReaderHostsByPriority(hosts: HostInfo[]): HostInfo[] {
@@ -321,18 +336,9 @@ class ConnectionAttemptTask {
         this.taskHandler.setSelectedConnectionAttemptTask(this.failoverTaskId, this.taskId);
         return new ReaderFailoverResult(this.targetClient, this.newHost, true, undefined, this.taskId);
       }
-      await this.pluginService.abortTargetClient(this.targetClient);
-      return new ReaderFailoverResult(null, null, false, undefined, this.taskId);
+      throw new AwsWrapperError(Messages.get("ClusterAwareReaderFailoverHandler.selectedTaskChosen", this.newHost.host));
     } catch (error) {
       this.pluginService.setAvailability(this.newHost.allAliases, HostAvailability.NOT_AVAILABLE);
-      if (error instanceof Error) {
-        // Propagate errors that are not caused by network errors.
-        if (!this.pluginService.isNetworkError(error)) {
-          return new ReaderFailoverResult(null, null, false, error, this.taskId);
-        }
-
-        return new ReaderFailoverResult(null, null, false, undefined, this.taskId);
-      }
       throw error;
     } finally {
       await this.performFinalCleanup();

common/lib/utils/locales/en.json

@@ -25,6 +25,8 @@
   "ClusterAwareReaderFailoverHandler.attemptingReaderConnection": "Trying to connect to reader: '%s', with properties '%s'",
   "ClusterAwareReaderFailoverHandler.successfulReaderConnection": "Connected to reader: '%s'",
   "ClusterAwareReaderFailoverHandler.failedReaderConnection": "Failed to connect to reader: '%s'",
+  "ClusterAwareReaderFailoverHandler.batchFailed": "Reader connections for hosts [%s] failed with the following errors: %s",
+  "ClusterAwareReaderFailoverHandler.selectedTaskChosen": "Selected task has already been chosen. Abort client for host: %s",
   "Utils.topology": "Topology: %s",
   "RdsHostListProvider.incorrectDialect": "Dialect needs to be a topology aware dialect.",
   "RdsHostListProvider.suggestedClusterId": "ClusterId '%s' is suggested for url '%s'.",

tests/unit/reader_failover_handler.test.ts

@@ -25,6 +25,7 @@ import { ClientWrapper } from "../../common/lib/client_wrapper";
 import { PgDatabaseDialect } from "../../pg/lib/dialect/pg_database_dialect";
 import { NodePostgresDriverDialect } from "../../pg/lib/dialect/node_postgres_driver_dialect";
 import { PgClientWrapper } from "../../common/lib/pg_client_wrapper";
+import { sleep } from "../../common/lib/utils/utils";
 
 const host1 = new HostInfo("writer", 1234, HostRole.WRITER);
 const host2 = new HostInfo("reader1", 1234, HostRole.READER);
@@ -85,6 +86,49 @@ describe("reader failover handler", () => {
     expect(result.newHost).toBe(hosts[successHostIndex]);
   }, 30000);
 
+  it("test failover - batch failure", async () => {
+    const expectedClients: ClientWrapper[] = [];
+    const hosts = [...defaultHosts];
+    const successHostIndex = 1;
+
+    when(mockPluginService.getHosts()).thenReturn(hosts);
+    when(await mockPluginService.getHostRole(anything())).thenReturn(HostRole.READER);
+
+    for (let i = 0; i < hosts.length; i++) {
+      if (i === successHostIndex) {
+        const client = new PgClientWrapper({}, hosts[i], properties);
+        expectedClients.push(client);
+        when(mockPluginService.forceConnect(hosts[i], anything())).thenCall(async () => {
+          await sleep(100);
+          return client;
+        });
+      } else {
+        when(mockPluginService.forceConnect(hosts[i], anything())).thenCall(async () => {
+          await sleep(100);
+          throw new AwsWrapperError("Rejecting test");
+        });
+        when(mockPluginService.isNetworkError(anything())).thenReturn(true);
+        expectedClients.push(undefined);
+      }
+    }
+    const mockPluginServiceInstance = instance(mockPluginService);
+
+    const target = new ClusterAwareReaderFailoverHandler(
+      mockPluginServiceInstance,
+      properties,
+      ClusterAwareReaderFailoverHandler.DEFAULT_FAILOVER_TIMEOUT,
+      ClusterAwareReaderFailoverHandler.DEFAULT_READER_CONNECT_TIMEOUT,
+      false
+    );
+    const result = await target.getConnectionFromHostGroup(hosts);
+    expect(result.isConnected).toBe(true);
+    expect(result.client).toBe(expectedClients[successHostIndex]);
+    expect(result.newHost).toBe(hosts[successHostIndex]);
+    verify(mockPluginService.forceConnect(hosts[successHostIndex], anything())).once();
+    verify(mockPluginService.abortTargetClient(undefined)).once();
+    verify(mockPluginService.abortTargetClient(expectedClients[successHostIndex])).never();
+  }, 30000);
+
   it("test failover timeout", async () => {
     // original host list: [active writer, active reader, current connection (reader), active
     // reader, down reader, active reader]

tests/unit/writer_failover_handler.test.ts

@@ -28,6 +28,7 @@ import { WriterFailoverResult } from "../../common/lib/plugins/failover/writer_f
 import { ClientWrapper } from "../../common/lib/client_wrapper";
 import { PgDatabaseDialect } from "../../pg/lib/dialect/pg_database_dialect";
 import { MySQLClientWrapper } from "../../common/lib/mysql_client_wrapper";
+import { MySQL2DriverDialect } from "../../mysql/lib/dialect/mysql2_driver_dialect";
 
 const builder = new HostInfoBuilder({ hostAvailabilityStrategy: new SimpleHostAvailabilityStrategy() });
 
@@ -46,10 +47,20 @@ const mockPluginService = mock(PluginService);
 const mockReaderFailover = mock(ClusterAwareReaderFailoverHandler);
 
 const mockTargetClient = { client: 123 };
-const mockClientWrapper: ClientWrapper = new MySQLClientWrapper(mockTargetClient, builder.withHost("host").build(), new Map<string, any>());
+const mockClientWrapper: ClientWrapper = new MySQLClientWrapper(
+  mockTargetClient,
+  builder.withHost("host").build(),
+  new Map<string, any>(),
+  new MySQL2DriverDialect()
+);
 
 const mockTargetClientB = { client: 456 };
-const mockClientWrapperB: ClientWrapper = new MySQLClientWrapper(mockTargetClientB, builder.withHost("host").build(), new Map<string, any>());
+const mockClientWrapperB: ClientWrapper = new MySQLClientWrapper(
+  mockTargetClientB,
+  builder.withHost("host").build(),
+  new Map<string, any>(),
+  new MySQL2DriverDialect()
+);
 
 describe("writer failover handler", () => {
   beforeEach(() => {