refactor(NODE-6230): executeOperation to use iterative retry mechanism (#4157)

Author: W-A-James

src/operations/command.ts

@@ -104,7 +104,7 @@ export abstract class CommandOperation<T> extends AbstractOperation<T> {
     if (this.hasAspect(Aspect.EXPLAINABLE)) {
       return this.explain == null;
     }
-    return true;
+    return super.canRetryWrite;
   }
 
   public async executeCommand<T extends MongoDBResponseConstructor>(

src/operations/execute_operation.ts

@@ -24,7 +24,7 @@ import {
 } from '../sdam/server_selection';
 import type { Topology } from '../sdam/topology';
 import type { ClientSession } from '../sessions';
-import { squashError, supportsRetryableWrites } from '../utils';
+import { supportsRetryableWrites } from '../utils';
 import { AbstractOperation, Aspect } from './operation';
 
 const MMAPv1_RETRY_WRITES_ERROR_CODE = MONGODB_ERROR_CODES.IllegalOperation;
@@ -45,10 +45,9 @@ type ResultTypeFromOperation<TOperation> = TOperation extends AbstractOperation<
  * not provided.
  *
  * The expectation is that this function:
- * - Connects the MongoClient if it has not already been connected
+ * - Connects the MongoClient if it has not already been connected, see {@link autoConnect}
  * - Creates a session if none is provided and cleans up the session it creates
- * - Selects a server based on readPreference or various factors
- * - Retries an operation if it fails for certain errors, see {@link retryOperation}
+ * - Tries an operation and retries under certain conditions, see {@link tryOperation}
  *
  * @typeParam T - The operation's type
  * @typeParam TResult - The type of the operation's result, calculated from T
@@ -65,23 +64,7 @@ export async function executeOperation<
     throw new MongoRuntimeError('This method requires a valid operation instance');
   }
 
-  if (client.topology == null) {
-    // Auto connect on operation
-    if (client.s.hasBeenClosed) {
-      throw new MongoNotConnectedError('Client must be connected before running operations');
-    }
-    client.s.options[Symbol.for('@@mdb.skipPingOnConnect')] = true;
-    try {
-      await client.connect();
-    } finally {
-      delete client.s.options[Symbol.for('@@mdb.skipPingOnConnect')];
-    }
-  }
-
-  const { topology } = client;
-  if (topology == null) {
-    throw new MongoRuntimeError('client.connect did not create a topology but also did not throw');
-  }
+  const topology = await autoConnect(client);
 
   // The driver sessions spec mandates that we implicitly create sessions for operations
   // that are not explicitly provided with a session.
@@ -108,7 +91,6 @@ export async function executeOperation<
   const inTransaction = !!session?.inTransaction();
 
   const hasReadAspect = operation.hasAspect(Aspect.READ_OPERATION);
-  const hasWriteAspect = operation.hasAspect(Aspect.WRITE_OPERATION);
 
   if (
     inTransaction &&
@@ -124,6 +106,73 @@ export async function executeOperation<
     session.unpin();
   }
 
+  try {
+    return await tryOperation(operation, {
+      topology,
+      session,
+      readPreference
+    });
+  } finally {
+    if (session?.owner != null && session.owner === owner) {
+      await session.endSession();
+    }
+  }
+}
+
+/**
+ * Connects a client if it has not yet been connected
+ * @internal
+ */
+async function autoConnect(client: MongoClient): Promise<Topology> {
+  if (client.topology == null) {
+    if (client.s.hasBeenClosed) {
+      throw new MongoNotConnectedError('Client must be connected before running operations');
+    }
+    client.s.options[Symbol.for('@@mdb.skipPingOnConnect')] = true;
+    try {
+      await client.connect();
+      if (client.topology == null) {
+        throw new MongoRuntimeError(
+          'client.connect did not create a topology but also did not throw'
+        );
+      }
+      return client.topology;
+    } finally {
+      delete client.s.options[Symbol.for('@@mdb.skipPingOnConnect')];
+    }
+  }
+  return client.topology;
+}
+
+/** @internal */
+type RetryOptions = {
+  session: ClientSession | undefined;
+  readPreference: ReadPreference;
+  topology: Topology;
+};
+
+/**
+ * Executes an operation and retries as appropriate
+ * @internal
+ *
+ * @remarks
+ * Implements behaviour described in [Retryable Reads](https://github.com/mongodb/specifications/blob/master/source/retryable-reads/retryable-reads.md) and [Retryable
+ * Writes](https://github.com/mongodb/specifications/blob/master/source/retryable-writes/retryable-writes.md) specification
+ *
+ * This function:
+ * - performs initial server selection
+ * - attempts to execute an operation
+ * - retries the operation if it meets the criteria for a retryable read or a retryable write
+ *
+ * @typeParam T - The operation's type
+ * @typeParam TResult - The type of the operation's result, calculated from T
+ *
+ * @param operation - The operation to execute
+ * */
+async function tryOperation<
+  T extends AbstractOperation<TResult>,
+  TResult = ResultTypeFromOperation<T>
+>(operation: T, { topology, session, readPreference }: RetryOptions): Promise<TResult> {
   let selector: ReadPreference | ServerSelector;
 
   if (operation.hasAspect(Aspect.MUST_SELECT_SAME_SERVER)) {
@@ -139,30 +188,14 @@ export async function executeOperation<
     selector = readPreference;
   }
 
-  const server = await topology.selectServer(selector, {
+  let server = await topology.selectServer(selector, {
     session,
     operationName: operation.commandName
   });
 
-  if (session == null) {
-    // No session also means it is not retryable, early exit
-    return await operation.execute(server, undefined);
-  }
-
-  if (!operation.hasAspect(Aspect.RETRYABLE)) {
-    // non-retryable operation, early exit
-    try {
-      return await operation.execute(server, session);
-    } finally {
-      if (session?.owner != null && session.owner === owner) {
-        try {
-          await session.endSession();
-        } catch (error) {
-          squashError(error);
-        }
-      }
-    }
-  }
+  const hasReadAspect = operation.hasAspect(Aspect.READ_OPERATION);
+  const hasWriteAspect = operation.hasAspect(Aspect.WRITE_OPERATION);
+  const inTransaction = session?.inTransaction() ?? false;
 
   const willRetryRead = topology.s.options.retryReads && !inTransaction && operation.canRetryRead;
 
@@ -172,105 +205,76 @@ export async function executeOperation<
     supportsRetryableWrites(server) &&
     operation.canRetryWrite;
 
-  const willRetry = (hasReadAspect && willRetryRead) || (hasWriteAspect && willRetryWrite);
+  const willRetry =
+    operation.hasAspect(Aspect.RETRYABLE) &&
+    session != null &&
+    ((hasReadAspect && willRetryRead) || (hasWriteAspect && willRetryWrite));
 
-  if (hasWriteAspect && willRetryWrite) {
+  if (hasWriteAspect && willRetryWrite && session != null) {
     operation.options.willRetryWrite = true;
     session.incrementTransactionNumber();
   }
 
-  try {
-    return await operation.execute(server, session);
-  } catch (operationError) {
-    if (willRetry && operationError instanceof MongoError) {
-      return await retryOperation(operation, operationError, {
-        session,
-        topology,
-        selector,
-        previousServer: server.description
-      });
-    }
-    throw operationError;
-  } finally {
-    if (session?.owner != null && session.owner === owner) {
-      try {
-        await session.endSession();
-      } catch (error) {
-        squashError(error);
-      }
-    }
-  }
-}
+  // TODO(NODE-6231): implement infinite retry within CSOT timeout here
+  const maxTries = willRetry ? 2 : 1;
+  let previousOperationError: MongoError | undefined;
+  let previousServer: ServerDescription | undefined;
 
-/** @internal */
-type RetryOptions = {
-  session: ClientSession;
-  topology: Topology;
-  selector: ReadPreference | ServerSelector;
-  previousServer: ServerDescription;
-};
+  // TODO(NODE-6231): implement infinite retry within CSOT timeout here
+  for (let tries = 0; tries < maxTries; tries++) {
+    if (previousOperationError) {
+      if (hasWriteAspect && previousOperationError.code === MMAPv1_RETRY_WRITES_ERROR_CODE) {
+        throw new MongoServerError({
+          message: MMAPv1_RETRY_WRITES_ERROR_MESSAGE,
+          errmsg: MMAPv1_RETRY_WRITES_ERROR_MESSAGE,
+          originalError: previousOperationError
+        });
+      }
 
-async function retryOperation<
-  T extends AbstractOperation<TResult>,
-  TResult = ResultTypeFromOperation<T>
->(
-  operation: T,
-  originalError: MongoError,
-  { session, topology, selector, previousServer }: RetryOptions
-): Promise<TResult> {
-  const isWriteOperation = operation.hasAspect(Aspect.WRITE_OPERATION);
-  const isReadOperation = operation.hasAspect(Aspect.READ_OPERATION);
+      if (hasWriteAspect && !isRetryableWriteError(previousOperationError))
+        throw previousOperationError;
 
-  if (isWriteOperation && originalError.code === MMAPv1_RETRY_WRITES_ERROR_CODE) {
-    throw new MongoServerError({
-      message: MMAPv1_RETRY_WRITES_ERROR_MESSAGE,
-      errmsg: MMAPv1_RETRY_WRITES_ERROR_MESSAGE,
-      originalError
-    });
-  }
+      if (hasReadAspect && !isRetryableReadError(previousOperationError))
+        throw previousOperationError;
 
-  if (isWriteOperation && !isRetryableWriteError(originalError)) {
-    throw originalError;
-  }
-
-  if (isReadOperation && !isRetryableReadError(originalError)) {
-    throw originalError;
-  }
+      if (
+        previousOperationError instanceof MongoNetworkError &&
+        operation.hasAspect(Aspect.CURSOR_CREATING) &&
+        session != null &&
+        session.isPinned &&
+        !session.inTransaction()
+      ) {
+        session.unpin({ force: true, forceClear: true });
+      }
 
-  if (
-    originalError instanceof MongoNetworkError &&
-    session.isPinned &&
-    !session.inTransaction() &&
-    operation.hasAspect(Aspect.CURSOR_CREATING)
-  ) {
-    // If we have a cursor and the initial command fails with a network error,
-    // we can retry it on another connection. So we need to check it back in, clear the
-    // pool for the service id, and retry again.
-    session.unpin({ force: true, forceClear: true });
-  }
+      server = await topology.selectServer(selector, {
+        session,
+        operationName: operation.commandName,
+        previousServer
+      });
 
-  // select a new server, and attempt to retry the operation
-  const server = await topology.selectServer(selector, {
-    session,
-    operationName: operation.commandName,
-    previousServer
-  });
+      if (hasWriteAspect && !supportsRetryableWrites(server)) {
+        throw new MongoUnexpectedServerResponseError(
+          'Selected server does not support retryable writes'
+        );
+      }
+    }
 
-  if (isWriteOperation && !supportsRetryableWrites(server)) {
-    throw new MongoUnexpectedServerResponseError(
-      'Selected server does not support retryable writes'
-    );
-  }
+    try {
+      return await operation.execute(server, session);
+    } catch (operationError) {
+      if (!(operationError instanceof MongoError)) throw operationError;
 
-  try {
-    return await operation.execute(server, session);
-  } catch (retryError) {
-    if (
-      retryError instanceof MongoError &&
-      retryError.hasErrorLabel(MongoErrorLabel.NoWritesPerformed)
-    ) {
-      throw originalError;
+      if (
+        previousOperationError != null &&
+        operationError.hasErrorLabel(MongoErrorLabel.NoWritesPerformed)
+      ) {
+        throw previousOperationError;
+      }
+      previousServer = server.description;
+      previousOperationError = operationError;
     }
-    throw retryError;
   }
+
+  throw previousOperationError;
 }

src/operations/operation.ts

@@ -102,11 +102,11 @@ export abstract class AbstractOperation<TResult = any> {
   }
 
   get canRetryRead(): boolean {
-    return true;
+    return this.hasAspect(Aspect.RETRYABLE) && this.hasAspect(Aspect.READ_OPERATION);
   }
 
   get canRetryWrite(): boolean {
-    return true;
+    return this.hasAspect(Aspect.RETRYABLE) && this.hasAspect(Aspect.WRITE_OPERATION);
   }
 }