refactor(NODE-5696): add async-iterator based socket helpers (#3896)

Co-authored-by: Neal Beeken <neal.beeken@mongodb.com>

src/cmap/command_monitoring_events.ts

@@ -7,7 +7,7 @@ import {
   LEGACY_HELLO_COMMAND_CAMEL_CASE
 } from '../constants';
 import { calculateDurationInMs, deepCopy } from '../utils';
-import { Msg, type Query, type WriteProtocolMessageType } from './commands';
+import { OpMsgRequest, type OpQueryRequest, type WriteProtocolMessageType } from './commands';
 import type { Connection } from './connection';
 
 /**
@@ -181,8 +181,8 @@ const HELLO_COMMANDS = new Set(['hello', LEGACY_HELLO_COMMAND, LEGACY_HELLO_COMM
 
 // helper methods
 const extractCommandName = (commandDoc: Document) => Object.keys(commandDoc)[0];
-const namespace = (command: Query) => command.ns;
-const collectionName = (command: Query) => command.ns.split('.')[1];
+const namespace = (command: OpQueryRequest) => command.ns;
+const collectionName = (command: OpQueryRequest) => command.ns.split('.')[1];
 const maybeRedact = (commandName: string, commandDoc: Document, result: Error | Document) =>
   SENSITIVE_COMMANDS.has(commandName) ||
   (HELLO_COMMANDS.has(commandName) && commandDoc.speculativeAuthenticate)
@@ -220,7 +220,7 @@ const OP_QUERY_KEYS = [
 
 /** Extract the actual command from the query, possibly up-converting if it's a legacy format */
 function extractCommand(command: WriteProtocolMessageType): Document {
-  if (command instanceof Msg) {
+  if (command instanceof OpMsgRequest) {
     return deepCopy(command.command);
   }
 
@@ -283,7 +283,7 @@ function extractReply(command: WriteProtocolMessageType, reply?: Document) {
     return reply;
   }
 
-  if (command instanceof Msg) {
+  if (command instanceof OpMsgRequest) {
     return deepCopy(reply.result ? reply.result : reply);
   }
 

src/cmap/commands.ts

@@ -4,7 +4,13 @@ import { MongoInvalidArgumentError, MongoRuntimeError } from '../error';
 import { ReadPreference } from '../read_preference';
 import type { ClientSession } from '../sessions';
 import type { CommandOptions } from './connection';
-import { OP_MSG, OP_QUERY } from './wire_protocol/constants';
+import {
+  compress,
+  Compressor,
+  type CompressorName,
+  uncompressibleCommands
+} from './wire_protocol/compression';
+import { OP_COMPRESSED, OP_MSG, OP_QUERY } from './wire_protocol/constants';
 
 // Incrementing request id
 let _requestId = 0;
@@ -25,7 +31,7 @@ const SHARD_CONFIG_STALE = 4;
 const AWAIT_CAPABLE = 8;
 
 /** @internal */
-export type WriteProtocolMessageType = Query | Msg;
+export type WriteProtocolMessageType = OpQueryRequest | OpMsgRequest;
 
 /** @internal */
 export interface OpQueryOptions extends CommandOptions {
@@ -52,7 +58,7 @@ export interface OpQueryOptions extends CommandOptions {
  * QUERY
  **************************************************************/
 /** @internal */
-export class Query {
+export class OpQueryRequest {
   ns: string;
   numberToSkip: number;
   numberToReturn: number;
@@ -96,7 +102,7 @@ export class Query {
     this.numberToSkip = options.numberToSkip || 0;
     this.numberToReturn = options.numberToReturn || 0;
     this.returnFieldSelector = options.returnFieldSelector || undefined;
-    this.requestId = Query.getRequestId();
+    this.requestId = options.requestId ?? OpQueryRequest.getRequestId();
 
     // special case for pre-3.2 find commands, delete ASAP
     this.pre32Limit = options.pre32Limit;
@@ -285,7 +291,7 @@ export interface OpResponseOptions extends BSONSerializeOptions {
 }
 
 /** @internal */
-export class Response {
+export class OpQueryResponse {
   parsed: boolean;
   raw: Buffer;
   data: Buffer;
@@ -472,7 +478,7 @@ export interface OpMsgOptions {
 }
 
 /** @internal */
-export class Msg {
+export class OpMsgRequest {
   requestId: number;
   serializeFunctions: boolean;
   ignoreUndefined: boolean;
@@ -502,7 +508,7 @@ export class Msg {
     this.options = options ?? {};
 
     // Additional options
-    this.requestId = options.requestId ? options.requestId : Msg.getRequestId();
+    this.requestId = options.requestId ? options.requestId : OpMsgRequest.getRequestId();
 
     // Serialization option
     this.serializeFunctions =
@@ -580,7 +586,7 @@ export class Msg {
 }
 
 /** @internal */
-export class BinMsg {
+export class OpMsgResponse {
   parsed: boolean;
   raw: Buffer;
   data: Buffer;
@@ -709,3 +715,54 @@ export class BinMsg {
     return { utf8: { writeErrors: false } };
   }
 }
+
+const MESSAGE_HEADER_SIZE = 16;
+const COMPRESSION_DETAILS_SIZE = 9; // originalOpcode + uncompressedSize, compressorID
+
+/**
+ * @internal
+ *
+ * An OP_COMPRESSED request wraps either an OP_QUERY or OP_MSG message.
+ */
+export class OpCompressedRequest {
+  constructor(
+    private command: WriteProtocolMessageType,
+    private options: { zlibCompressionLevel: number; agreedCompressor: CompressorName }
+  ) {}
+
+  // Return whether a command contains an uncompressible command term
+  // Will return true if command contains no uncompressible command terms
+  static canCompress(command: WriteProtocolMessageType) {
+    const commandDoc = command instanceof OpMsgRequest ? command.command : command.query;
+    const commandName = Object.keys(commandDoc)[0];
+    return !uncompressibleCommands.has(commandName);
+  }
+
+  async toBin(): Promise<Buffer[]> {
+    const concatenatedOriginalCommandBuffer = Buffer.concat(this.command.toBin());
+    // otherwise, compress the message
+    const messageToBeCompressed = concatenatedOriginalCommandBuffer.slice(MESSAGE_HEADER_SIZE);
+
+    // Extract information needed for OP_COMPRESSED from the uncompressed message
+    const originalCommandOpCode = concatenatedOriginalCommandBuffer.readInt32LE(12);
+
+    // Compress the message body
+    const compressedMessage = await compress(this.options, messageToBeCompressed);
+    // Create the msgHeader of OP_COMPRESSED
+    const msgHeader = Buffer.alloc(MESSAGE_HEADER_SIZE);
+    msgHeader.writeInt32LE(
+      MESSAGE_HEADER_SIZE + COMPRESSION_DETAILS_SIZE + compressedMessage.length,
+      0
+    ); // messageLength
+    msgHeader.writeInt32LE(this.command.requestId, 4); // requestID
+    msgHeader.writeInt32LE(0, 8); // responseTo (zero)
+    msgHeader.writeInt32LE(OP_COMPRESSED, 12); // opCode
+
+    // Create the compression details of OP_COMPRESSED
+    const compressionDetails = Buffer.alloc(COMPRESSION_DETAILS_SIZE);
+    compressionDetails.writeInt32LE(originalCommandOpCode, 0); // originalOpcode
+    compressionDetails.writeInt32LE(messageToBeCompressed.length, 4); // Size of the uncompressed compressedMessage, excluding the MsgHeader
+    compressionDetails.writeUInt8(Compressor[this.options.agreedCompressor], 8); // compressorID
+    return [msgHeader, compressionDetails, compressedMessage];
+  }
+}