feat: implement COM_RESET_CONNECTION with pool integration

lib/base/connection.js

@@ -928,6 +928,10 @@ class BaseConnection extends EventEmitter {
     return this.addCommand(new Commands.Ping(cb));
   }
 
+  reset(cb) {
+    return this.addCommand(new Commands.ResetConnection(cb));
+  }
+
   _registerSlave(opts, cb) {
     return this.addCommand(new Commands.RegisterSlave(opts, cb));
   }

lib/base/pool.js

@@ -127,7 +127,37 @@ class BasePool extends EventEmitter {
         cb = this._connectionQueue.shift();
         process.nextTick(this.getConnection.bind(this, cb));
       }
-    } else if (this._connectionQueue.length) {
+      return;
+    }
+
+    // Reset connection state if configured
+    if (this.config.resetOnRelease && connection.reset) {
+      connection.reset((err) => {
+        if (err) {
+          // If reset fails, remove connection from pool
+          connection._pool = null;
+          spliceConnection(this._allConnections, connection);
+          connection.destroy();
+
+          // Try to create a new connection for waiting callbacks
+          if (this._connectionQueue.length) {
+            cb = this._connectionQueue.shift();
+            process.nextTick(this.getConnection.bind(this, cb));
+          }
+          return;
+        }
+
+        // Reset successful, continue with normal release flow
+        this._handleSuccessfulRelease(connection);
+      });
+    } else {
+      this._handleSuccessfulRelease(connection);
+    }
+  }
+
+  _handleSuccessfulRelease(connection) {
+    let cb;
+    if (this._connectionQueue.length) {
       cb = this._connectionQueue.shift();
       process.nextTick(() => {
         connection._released = false;

lib/commands/index.js

@@ -10,6 +10,7 @@ const Ping = require('./ping.js');
 const RegisterSlave = require('./register_slave.js');
 const BinlogDump = require('./binlog_dump.js');
 const ChangeUser = require('./change_user.js');
+const ResetConnection = require('./reset_connection.js');
 const Quit = require('./quit.js');
 
 module.exports = {
@@ -23,5 +24,6 @@ module.exports = {
   RegisterSlave,
   BinlogDump,
   ChangeUser,
+  ResetConnection,
   Quit,
 };

lib/commands/reset_connection.js

@@ -0,0 +1,29 @@
+'use strict';
+
+const Command = require('./command');
+const Packets = require('../packets/index.js');
+
+class ResetConnection extends Command {
+  constructor(callback) {
+    super();
+    this.onResult = callback;
+  }
+
+  start(packet, connection) {
+    const req = new Packets.ResetConnection();
+    connection.writePacket(req.toPacket());
+    return ResetConnection.prototype.resetConnectionResponse;
+  }
+
+  resetConnectionResponse(packet, connection) {
+    if (connection._statements) {
+      connection._statements.clear();
+    }
+    if (this.onResult) {
+      process.nextTick(this.onResult.bind(this, null));
+    }
+    return null;
+  }
+}
+
+module.exports = ResetConnection;

lib/constants/commands.js

@@ -32,5 +32,6 @@ module.exports = {
   STMT_FETCH: 0x1c,
   DAEMON: 0x1d, // deprecated
   BINLOG_DUMP_GTID: 0x1e,
+  RESET_CONNECTION: 0x1f, // introduced in 5.7.3
   UNKNOWN: 0xff, // bad!
 };

lib/packets/index.js

@@ -27,6 +27,7 @@ const PrepareStatement = require('./prepare_statement');
 const PreparedStatementHeader = require('./prepared_statement_header');
 const Query = require('./query');
 const RegisterSlave = require('./register_slave');
+const ResetConnection = require('./reset_connection');
 const ResultSetHeader = require('./resultset_header');
 const SSLRequest = require('./ssl_request');
 const TextRow = require('./text_row');
@@ -48,6 +49,7 @@ const ctorMap = {
   PreparedStatementHeader,
   Query,
   RegisterSlave,
+  ResetConnection,
   ResultSetHeader,
   SSLRequest,
   TextRow,

lib/packets/reset_connection.js

@@ -0,0 +1,17 @@
+'use strict';
+
+const Packet = require('../packets/packet');
+const CommandCodes = require('../constants/commands');
+
+class ResetConnection {
+  constructor() {}
+
+  toPacket() {
+    const packet = new Packet(0, Buffer.alloc(5), 0, 5);
+    packet.offset = 4;
+    packet.writeInt8(CommandCodes.RESET_CONNECTION);
+    return packet;
+  }
+}
+
+module.exports = ResetConnection;

lib/pool_config.js

@@ -24,6 +24,10 @@ class PoolConfig {
     this.queueLimit = isNaN(options.queueLimit)
       ? 0
       : Number(options.queueLimit);
+    this.resetOnRelease =
+      options.resetOnRelease === undefined
+        ? false
+        : Boolean(options.resetOnRelease);
   }
 }
 

lib/promise/connection.js

@@ -118,6 +118,25 @@ class PromiseConnection extends EventEmitter {
     });
   }
 
+  reset() {
+    const c = this.connection;
+    const localErr = new Error();
+    return new this.Promise((resolve, reject) => {
+      c.reset((err) => {
+        if (err) {
+          localErr.message = err.message;
+          localErr.code = err.code;
+          localErr.errno = err.errno;
+          localErr.sqlState = err.sqlState;
+          localErr.sqlMessage = err.sqlMessage;
+          reject(localErr);
+        } else {
+          resolve();
+        }
+      });
+    });
+  }
+
   connect() {
     const c = this.connection;
     const localErr = new Error();

promise.d.ts

@@ -51,6 +51,8 @@ export declare class Connection extends QueryableAndExecutableBase {
 
   ping(): Promise<void>;
 
+  reset(): Promise<void>;
+
   beginTransaction(): Promise<void>;
 
   commit(): Promise<void>;

test/common.test.mts

@@ -154,7 +154,7 @@ export const waitDatabaseReady = function (callback: () => void) {
   tryConnect();
 };
 
-export const getConfig = function (input?: ConnectionOptions) {
+export const getConfig = function (input?: ConnectionOptions | PoolOptions) {
   const args = input || {};
   const params = {
     host: args.host || config.host,
@@ -177,6 +177,7 @@ export const getConfig = function (input?: ConnectionOptions) {
     connectionLimit: args && args.connectionLimit,
     maxIdle: args && args.maxIdle,
     idleTimeout: args && args.idleTimeout,
+    resetOnRelease: args && (args as PoolOptions).resetOnRelease,
     jsonStrings: args && args.jsonStrings,
     disableEval,
     gracefulEnd: args && args.gracefulEnd,