feat(NODE-6337): implement client bulk write batching

src/cmap/commands.ts

@@ -429,10 +429,60 @@ export interface OpMsgOptions {
 
 /** @internal */
 export class DocumentSequence {
+  field: string;
   documents: Document[];
+  serializedDocumentsLength: number;
+  private chunks: Uint8Array[];
+  private header: Buffer;
 
-  constructor(documents: Document[]) {
-    this.documents = documents;
+  /**
+   * Create a new document sequence for the provided field.
+   * @param field - The field it will replace.
+   */
+  constructor(field: string, documents?: Document[]) {
+    this.field = field;
+    this.documents = [];
+    this.chunks = [];
+    this.serializedDocumentsLength = 0;
+    // Document sequences starts with type 1 at the first byte.
+    // Field strings must always be UTF-8.
+    const buffer = Buffer.allocUnsafe(1 + 4 + this.field.length + 1);
+    buffer[0] = 1;
+    // Third part is the field name at offset 5 with trailing null byte.
+    encodeUTF8Into(buffer, `${this.field}\0`, 5);
+    this.chunks.push(buffer);
+    this.header = buffer;
+    if (documents) {
+      for (const doc of documents) {
+        this.push(doc, BSON.serialize(doc));
+      }
+    }
+  }
+
+  /**
+   * Push a document to the document sequence. Will serialize the document
+   * as well and return the current serialized length of all documents.
+   * @param document - The document to add.
+   * @param buffer - The serialized document in raw BSON.
+   * @returns The new total document sequence length.
+   */
+  push(document: Document, buffer: Uint8Array): number {
+    this.serializedDocumentsLength += buffer.length;
+    // Push the document.
+    this.documents.push(document);
+    // Push the document raw bson.
+    this.chunks.push(buffer);
+    // Write the new length.
+    this.header?.writeInt32LE(4 + this.field.length + 1 + this.serializedDocumentsLength, 1);
+    return this.serializedDocumentsLength + this.header.length;
+  }
+
+  /**
+   * Get the fully serialized bytes for the document sequence section.
+   * @returns The section bytes.
+   */
+  toBin(): Uint8Array {
+    return Buffer.concat(this.chunks);
   }
 }
 
@@ -543,21 +593,7 @@ export class OpMsgRequest {
     const chunks = [];
     for (const [key, value] of Object.entries(document)) {
       if (value instanceof DocumentSequence) {
-        // Document sequences starts with type 1 at the first byte.
-        const buffer = Buffer.allocUnsafe(1 + 4 + key.length + 1);
-        buffer[0] = 1;
-        // Third part is the field name at offset 5 with trailing null byte.
-        encodeUTF8Into(buffer, `${key}\0`, 5);
-        chunks.push(buffer);
-        // Fourth part are the documents' bytes.
-        let docsLength = 0;
-        for (const doc of value.documents) {
-          const docBson = this.serializeBson(doc);
-          docsLength += docBson.length;
-          chunks.push(docBson);
-        }
-        // Second part of the sequence is the length at offset 1;
-        buffer.writeInt32LE(4 + key.length + 1 + docsLength, 1);
+        chunks.push(value.toBin());
         // Why are we removing the field from the command? This is because it needs to be
         // removed in the OP_MSG request first section, and DocumentSequence is not a
         // BSON type and is specific to the MongoDB wire protocol so there's nothing

src/cursor/client_bulk_write_cursor.ts

@@ -1,8 +1,10 @@
-import type { Document } from '../bson';
+import { type Document } from 'bson';
+
 import { type ClientBulkWriteCursorResponse } from '../cmap/wire_protocol/responses';
-import { MongoBulkWriteCursorError } from '../error';
+import { MongoClientBulkWriteCursorError } from '../error';
 import type { MongoClient } from '../mongo_client';
 import { ClientBulkWriteOperation } from '../operations/client_bulk_write/client_bulk_write';
+import { type ClientBulkWriteCommandBuilder } from '../operations/client_bulk_write/command_builder';
 import { type ClientBulkWriteOptions } from '../operations/client_bulk_write/common';
 import { executeOperation } from '../operations/execute_operation';
 import type { ClientSession } from '../sessions';
@@ -24,17 +26,21 @@ export interface ClientBulkWriteCursorOptions
  * @internal
  */
 export class ClientBulkWriteCursor extends AbstractCursor {
-  public readonly command: Document;
+  commandBuilder: ClientBulkWriteCommandBuilder;
   /** @internal */
   private cursorResponse?: ClientBulkWriteCursorResponse;
   /** @internal */
   private clientBulkWriteOptions: ClientBulkWriteOptions;
 
   /** @internal */
-  constructor(client: MongoClient, command: Document, options: ClientBulkWriteOptions = {}) {
+  constructor(
+    client: MongoClient,
+    commandBuilder: ClientBulkWriteCommandBuilder,
+    options: ClientBulkWriteOptions = {}
+  ) {
     super(client, new MongoDBNamespace('admin', '$cmd'), options);
 
-    this.command = command;
+    this.commandBuilder = commandBuilder;
     this.clientBulkWriteOptions = options;
   }
 
@@ -44,22 +50,29 @@ export class ClientBulkWriteCursor extends AbstractCursor {
    */
   get response(): ClientBulkWriteCursorResponse {
     if (this.cursorResponse) return this.cursorResponse;
-    throw new MongoBulkWriteCursorError(
+    throw new MongoClientBulkWriteCursorError(
       'No client bulk write cursor response returned from the server.'
     );
   }
 
+  /**
+   * Get the last set of operations the cursor executed.
+   */
+  get operations(): Document[] {
+    return this.commandBuilder.lastOperations;
+  }
+
   clone(): ClientBulkWriteCursor {
     const clonedOptions = mergeOptions({}, this.clientBulkWriteOptions);
     delete clonedOptions.session;
-    return new ClientBulkWriteCursor(this.client, this.command, {
+    return new ClientBulkWriteCursor(this.client, this.commandBuilder, {
       ...clonedOptions
     });
   }
 
   /** @internal */
   async _initialize(session: ClientSession): Promise<InitialCursorResponse> {
-    const clientBulkWriteOperation = new ClientBulkWriteOperation(this.command, {
+    const clientBulkWriteOperation = new ClientBulkWriteOperation(this.commandBuilder, {
       ...this.clientBulkWriteOptions,
       ...this.cursorOptions,
       session

src/error.ts

@@ -622,7 +622,7 @@ export class MongoGCPError extends MongoOIDCError {
  * @public
  * @category Error
  */
-export class MongoBulkWriteCursorError extends MongoRuntimeError {
+export class MongoClientBulkWriteCursorError extends MongoRuntimeError {
   /**
    * **Do not use this constructor!**
    *
@@ -639,7 +639,34 @@ export class MongoBulkWriteCursorError extends MongoRuntimeError {
   }
 
   override get name(): string {
-    return 'MongoBulkWriteCursorError';
+    return 'MongoClientBulkWriteCursorError';
+  }
+}
+
+/**
+ * An error indicating that an error occurred on the client when executing a client bulk write.
+ *
+ * @public
+ * @category Error
+ */
+export class MongoClientBulkWriteExecutionError extends MongoRuntimeError {
+  /**
+   * **Do not use this constructor!**
+   *
+   * Meant for internal use only.
+   *
+   * @remarks
+   * This class is only meant to be constructed within the driver. This constructor is
+   * not subject to semantic versioning compatibility guarantees and may change at any time.
+   *
+   * @public
+   **/
+  constructor(message: string) {
+    super(message);
+  }
+
+  override get name(): string {
+    return 'MongoClientBulkWriteExecutionError';
   }
 }
 

src/index.ts

@@ -44,8 +44,9 @@ export {
   MongoAWSError,
   MongoAzureError,
   MongoBatchReExecutionError,
-  MongoBulkWriteCursorError,
   MongoChangeStreamError,
+  MongoClientBulkWriteCursorError,
+  MongoClientBulkWriteExecutionError,
   MongoCompatibilityError,
   MongoCursorExhaustedError,
   MongoCursorInUseError,

src/operations/client_bulk_write/client_bulk_write.ts

@@ -1,28 +1,28 @@
-import { type Document } from 'bson';
-
+import { MongoClientBulkWriteExecutionError, ServerType } from '../../beta';
 import { ClientBulkWriteCursorResponse } from '../../cmap/wire_protocol/responses';
 import type { Server } from '../../sdam/server';
 import type { ClientSession } from '../../sessions';
 import { MongoDBNamespace } from '../../utils';
 import { CommandOperation } from '../command';
 import { Aspect, defineAspects } from '../operation';
+import { type ClientBulkWriteCommandBuilder } from './command_builder';
 import { type ClientBulkWriteOptions } from './common';
 
 /**
  * Executes a single client bulk write operation within a potential batch.
  * @internal
  */
 export class ClientBulkWriteOperation extends CommandOperation<ClientBulkWriteCursorResponse> {
-  command: Document;
+  commandBuilder: ClientBulkWriteCommandBuilder;
   override options: ClientBulkWriteOptions;
 
   override get commandName() {
     return 'bulkWrite' as const;
   }
 
-  constructor(command: Document, options: ClientBulkWriteOptions) {
+  constructor(commandBuilder: ClientBulkWriteCommandBuilder, options: ClientBulkWriteOptions) {
     super(undefined, options);
-    this.command = command;
+    this.commandBuilder = commandBuilder;
     this.options = options;
     this.ns = new MongoDBNamespace('admin', '$cmd');
   }
@@ -37,9 +37,40 @@ export class ClientBulkWriteOperation extends CommandOperation<ClientBulkWriteCu
     server: Server,
     session: ClientSession | undefined
   ): Promise<ClientBulkWriteCursorResponse> {
-    return await super.executeCommand(server, session, this.command, ClientBulkWriteCursorResponse);
+    let command;
+
+    if (server.description.type === ServerType.LoadBalancer) {
+      if (session) {
+        // Checkout a connection to build the command.
+        const connection = await server.pool.checkOut();
+        // Pin the connection to the session so it get used to execute the command and we do not
+        // perform a double check-in/check-out.
+        session.pin(connection);
+        command = this.commandBuilder.buildBatch(
+          connection.hello?.maxMessageSizeBytes,
+          connection.hello?.maxWriteBatchSize
+        );
+      } else {
+        throw new MongoClientBulkWriteExecutionError(
+          'Session provided to the client bulk write operation must be present.'
+        );
+      }
+    } else {
+      // At this point we have a server and the auto connect code has already
+      // run in executeOperation, so the server description will be populated.
+      // We can use that to build the command.
+      command = this.commandBuilder.buildBatch(
+        server.description.maxMessageSizeBytes,
+        server.description.maxWriteBatchSize
+      );
+    }
+    return await super.executeCommand(server, session, command, ClientBulkWriteCursorResponse);
   }
 }
 
 // Skipping the collation as it goes on the individual ops.
-defineAspects(ClientBulkWriteOperation, [Aspect.WRITE_OPERATION, Aspect.SKIP_COLLATION]);
+defineAspects(ClientBulkWriteOperation, [
+  Aspect.WRITE_OPERATION,
+  Aspect.SKIP_COLLATION,
+  Aspect.CURSOR_CREATING
+]);