From 33da6f768dbb8f37cb450402644fac315a30364e Mon Sep 17 00:00:00 2001
From: Thomas Praxl <thomas@praxl.me>
Date: Fri, 27 Sep 2024 15:43:10 +0200
Subject: [PATCH 1/3] fix(lib): circular dependency index.js <-> lib

pool.js and pool_connection.js required index.js, and
index.js required pool.js and pool_connection.js.

Circular dependency can cause all sorts of problems.
This fix aims to provide a step towards fixing a problem with
@opentelemetry/instrumentation-mysql2, which looses several
exports when using its patched require.

For instance, `format` is lost and can cause an instrumented
application to crash.
---
 lib/pool.js            | 9 ++++-----
 lib/pool_connection.js | 2 +-
 2 files changed, 5 insertions(+), 6 deletions(-)

diff --git a/lib/pool.js b/lib/pool.js
index dc638d743e..7f73db8b00 100644
--- a/lib/pool.js
+++ b/lib/pool.js
@@ -1,8 +1,7 @@
 'use strict';
 
 const process = require('process');
-const mysql = require('../index.js');
-
+const SqlString = require('sqlstring');
 const EventEmitter = require('events').EventEmitter;
 const PoolConnection = require('./pool_connection.js');
 const Queue = require('denque');
@@ -214,7 +213,7 @@ class Pool extends EventEmitter {
   }
 
   format(sql, values) {
-    return mysql.format(
+    return SqlString.format(
       sql,
       values,
       this.config.connectionConfig.stringifyObjects,
@@ -223,7 +222,7 @@ class Pool extends EventEmitter {
   }
 
   escape(value) {
-    return mysql.escape(
+    return SqlString.escape(
       value,
       this.config.connectionConfig.stringifyObjects,
       this.config.connectionConfig.timezone
@@ -231,7 +230,7 @@ class Pool extends EventEmitter {
   }
 
   escapeId(value) {
-    return mysql.escapeId(value, false);
+    return SqlString.escapeId(value, false);
   }
 }
 
diff --git a/lib/pool_connection.js b/lib/pool_connection.js
index 78aac6d6b8..5760f9a468 100644
--- a/lib/pool_connection.js
+++ b/lib/pool_connection.js
@@ -1,6 +1,6 @@
 'use strict';
 
-const Connection = require('../index.js').Connection;
+const Connection = require('./connection.js');
 
 class PoolConnection extends Connection {
   constructor(pool, options) {

From 40053ad8097289a736f59fdb3457dea1c14f5e98 Mon Sep 17 00:00:00 2001
From: Thomas Praxl <thomas@praxl.me>
Date: Fri, 27 Sep 2024 18:01:07 +0200
Subject: [PATCH 2/3] fix: circular dependency index.js <-> promise.js

index.js and promise.js require each other.

Circular dependency can cause all sorts of problems.
This commit aims to fix a problem with
@opentelemetry/instrumentation-mysql2, which looses several
exports when using its patched require.

For instance, `format` is lost and can cause an instrumented
application to crash.
---
 common.js    | 19 +++++++++++++++++++
 index.js     | 20 ++++++--------------
 package.json |  1 +
 promise.js   | 34 +++++++++++++++++++---------------
 4 files changed, 45 insertions(+), 29 deletions(-)
 create mode 100644 common.js

diff --git a/common.js b/common.js
new file mode 100644
index 0000000000..66cd0b2bbb
--- /dev/null
+++ b/common.js
@@ -0,0 +1,19 @@
+'use strict';
+
+const Connection = require('./lib/connection.js');
+const ConnectionConfig = require('./lib/connection_config.js');
+const Pool = require('./lib/pool');
+const PoolConfig = require('./lib/pool_config');
+const PoolCluster = require('./lib/pool_cluster');
+
+exports.Connection = Connection;
+exports.createConnection = function(opts) {
+  return new Connection({ config: new ConnectionConfig(opts) });
+};
+exports.createPool = function(config) {
+  return new Pool({ config: new PoolConfig(config) });
+};
+exports.createPoolCluster = function(config) {
+  const PoolCluster = require('./lib/pool_cluster.js');
+  return new PoolCluster(config);
+};
diff --git a/index.js b/index.js
index f33455e3f4..928eec4d42 100644
--- a/index.js
+++ b/index.js
@@ -2,32 +2,24 @@
 
 const SqlString = require('sqlstring');
 
-const Connection = require('./lib/connection.js');
 const ConnectionConfig = require('./lib/connection_config.js');
 const parserCache = require('./lib/parsers/parser_cache');
 
-exports.createConnection = function(opts) {
-  return new Connection({ config: new ConnectionConfig(opts) });
-};
+const common = require('./common');
+exports.createConnection = common.createConnection
 
 exports.connect = exports.createConnection;
-exports.Connection = Connection;
+exports.Connection = common.Connection;
 exports.ConnectionConfig = ConnectionConfig;
 
 const Pool = require('./lib/pool.js');
 const PoolCluster = require('./lib/pool_cluster.js');
 
-exports.createPool = function(config) {
-  const PoolConfig = require('./lib/pool_config.js');
-  return new Pool({ config: new PoolConfig(config) });
-};
+exports.createPool = common.createPool
 
-exports.createPoolCluster = function(config) {
-  const PoolCluster = require('./lib/pool_cluster.js');
-  return new PoolCluster(config);
-};
+exports.createPoolCluster = common.createPoolCluster;
 
-exports.createQuery = Connection.createQuery;
+exports.createQuery = common.Connection.createQuery;
 
 exports.Pool = Pool;
 
diff --git a/package.json b/package.json
index b05dd0b628..07ab95d93f 100644
--- a/package.json
+++ b/package.json
@@ -43,6 +43,7 @@
     "typings/mysql",
     "index.js",
     "index.d.ts",
+    "common.js",
     "promise.js",
     "promise.d.ts"
   ],
diff --git a/promise.js b/promise.js
index 5d80e21e72..04eaff6433 100644
--- a/promise.js
+++ b/promise.js
@@ -1,8 +1,12 @@
 'use strict';
 
-const core = require('./index.js');
+const SqlString = require('sqlstring');
+const common = require('./common.js');
 const EventEmitter = require('events').EventEmitter;
 const parserCache = require('./lib/parsers/parser_cache.js');
+const PoolConnection = require('./lib/pool_connection.js');
+const Pool = require('./lib/pool.js');
+const PoolCluster = require('./lib/pool_cluster.js');
 
 function makeDoneCb(resolve, reject, localErr) {
   return function (err, rows, fields) {
@@ -249,7 +253,7 @@ class PromiseConnection extends EventEmitter {
 }
 
 function createConnection(opts) {
-  const coreConnection = core.createConnection(opts);
+  const coreConnection = common.createConnection(opts);
   const createConnectionErr = new Error();
   const thePromise = opts.Promise || Promise;
   if (!thePromise) {
@@ -286,12 +290,12 @@ function createConnection(opts) {
     const func = functionsToWrap[i];
 
     if (
-      typeof core.Connection.prototype[func] === 'function' &&
+      typeof common.Connection.prototype[func] === 'function' &&
       PromiseConnection.prototype[func] === undefined
     ) {
       PromiseConnection.prototype[func] = (function factory(funcName) {
         return function () {
-          return core.Connection.prototype[funcName].apply(
+          return common.Connection.prototype[funcName].apply(
             this.connection,
             arguments
           );
@@ -319,7 +323,7 @@ class PromisePoolConnection extends PromiseConnection {
   }
 
   destroy() {
-    return core.PoolConnection.prototype.destroy.apply(
+    return PoolConnection.prototype.destroy.apply(
       this.connection,
       arguments
     );
@@ -408,7 +412,7 @@ class PromisePool extends EventEmitter {
 }
 
 function createPool(opts) {
-  const corePool = core.createPool(opts);
+  const corePool = common.createPool(opts);
   const thePromise = opts.Promise || Promise;
   if (!thePromise) {
     throw new Error(
@@ -426,12 +430,12 @@ function createPool(opts) {
     const func = functionsToWrap[i];
 
     if (
-      typeof core.Pool.prototype[func] === 'function' &&
+      typeof Pool.prototype[func] === 'function' &&
       PromisePool.prototype[func] === undefined
     ) {
       PromisePool.prototype[func] = (function factory(funcName) {
         return function () {
-          return core.Pool.prototype[funcName].apply(this.pool, arguments);
+          return Pool.prototype[funcName].apply(this.pool, arguments);
         };
       })(func);
     }
@@ -527,12 +531,12 @@ class PromisePoolCluster extends EventEmitter {
     const func = functionsToWrap[i];
 
     if (
-      typeof core.PoolCluster.prototype[func] === 'function' &&
+      typeof PoolCluster.prototype[func] === 'function' &&
       PromisePoolCluster.prototype[func] === undefined
     ) {
       PromisePoolCluster.prototype[func] = (function factory(funcName) {
         return function () {
-          return core.PoolCluster.prototype[funcName].apply(this.poolCluster, arguments);
+          return PoolCluster.prototype[funcName].apply(this.poolCluster, arguments);
         };
       })(func);
     }
@@ -542,7 +546,7 @@ class PromisePoolCluster extends EventEmitter {
 ]);
 
 function createPoolCluster(opts) {
-  const corePoolCluster = core.createPoolCluster(opts);
+  const corePoolCluster = common.createPoolCluster(opts);
   const thePromise = (opts && opts.Promise) || Promise;
   if (!thePromise) {
     throw new Error(
@@ -557,10 +561,10 @@ function createPoolCluster(opts) {
 exports.createConnection = createConnection;
 exports.createPool = createPool;
 exports.createPoolCluster = createPoolCluster;
-exports.escape = core.escape;
-exports.escapeId = core.escapeId;
-exports.format = core.format;
-exports.raw = core.raw;
+exports.escape = SqlString.escape;
+exports.escapeId = SqlString.escapeId;
+exports.format = SqlString.format;
+exports.raw = SqlString.raw;
 exports.PromisePool = PromisePool;
 exports.PromiseConnection = PromiseConnection;
 exports.PromisePoolConnection = PromisePoolConnection;

From fbb8ab11333b075a098093328e06bdc59fdef87a Mon Sep 17 00:00:00 2001
From: Thomas Praxl <thomas@praxl.me>
Date: Sat, 28 Sep 2024 13:50:55 +0200
Subject: [PATCH 3/3] refactor: split common.js into lib modules

The proposal to put common.js into lib was good, but it felt
weird to arbitrarily stuff just some exported functions in
lib/common.js. This made sense when common.js was meant
to provide commons for index.js and promise.js. But
in the lib, this felt like a weird scope.

I therefore split common.js into

- lib/create_connection.js
- lib/create_pool.js
- lib/create_pool_cluster.js

Also made `require` more consistent in all affected files: all
`require` files now have a js suffix when they refer to a
single local file.
---
 common.js                  | 19 -------------------
 index.js                   | 18 ++++++++++--------
 lib/create_connection.js   | 10 ++++++++++
 lib/create_pool.js         | 10 ++++++++++
 lib/create_pool_cluster.js |  9 +++++++++
 package.json               |  1 -
 promise.js                 | 27 +++++++++++++++------------
 7 files changed, 54 insertions(+), 40 deletions(-)
 delete mode 100644 common.js
 create mode 100644 lib/create_connection.js
 create mode 100644 lib/create_pool.js
 create mode 100644 lib/create_pool_cluster.js

diff --git a/common.js b/common.js
deleted file mode 100644
index 66cd0b2bbb..0000000000
--- a/common.js
+++ /dev/null
@@ -1,19 +0,0 @@
-'use strict';
-
-const Connection = require('./lib/connection.js');
-const ConnectionConfig = require('./lib/connection_config.js');
-const Pool = require('./lib/pool');
-const PoolConfig = require('./lib/pool_config');
-const PoolCluster = require('./lib/pool_cluster');
-
-exports.Connection = Connection;
-exports.createConnection = function(opts) {
-  return new Connection({ config: new ConnectionConfig(opts) });
-};
-exports.createPool = function(config) {
-  return new Pool({ config: new PoolConfig(config) });
-};
-exports.createPoolCluster = function(config) {
-  const PoolCluster = require('./lib/pool_cluster.js');
-  return new PoolCluster(config);
-};
diff --git a/index.js b/index.js
index 928eec4d42..0d7179c2a7 100644
--- a/index.js
+++ b/index.js
@@ -3,23 +3,25 @@
 const SqlString = require('sqlstring');
 
 const ConnectionConfig = require('./lib/connection_config.js');
-const parserCache = require('./lib/parsers/parser_cache');
+const parserCache = require('./lib/parsers/parser_cache.js');
 
-const common = require('./common');
-exports.createConnection = common.createConnection
+const Connection = require('./lib/connection.js');
 
+exports.createConnection = require('./lib/create_connection.js');
 exports.connect = exports.createConnection;
-exports.Connection = common.Connection;
+exports.Connection = Connection
 exports.ConnectionConfig = ConnectionConfig;
 
 const Pool = require('./lib/pool.js');
 const PoolCluster = require('./lib/pool_cluster.js');
+const createPool = require('./lib/create_pool.js');
+const createPoolCluster = require('./lib/create_pool_cluster.js');
 
-exports.createPool = common.createPool
+exports.createPool = createPool
 
-exports.createPoolCluster = common.createPoolCluster;
+exports.createPoolCluster = createPoolCluster;
 
-exports.createQuery = common.Connection.createQuery;
+exports.createQuery = Connection.createQuery;
 
 exports.Pool = Pool;
 
@@ -34,7 +36,7 @@ exports.createServer = function(handler) {
   return s;
 };
 
-exports.PoolConnection = require('./lib/pool_connection');
+exports.PoolConnection = require('./lib/pool_connection.js');
 exports.authPlugins = require('./lib/auth_plugins');
 exports.escape = SqlString.escape;
 exports.escapeId = SqlString.escapeId;
diff --git a/lib/create_connection.js b/lib/create_connection.js
new file mode 100644
index 0000000000..d39618f78f
--- /dev/null
+++ b/lib/create_connection.js
@@ -0,0 +1,10 @@
+'use strict';
+
+const Connection = require('./connection.js');
+const ConnectionConfig = require('./connection_config.js');
+
+function createConnection(opts) {
+  return new Connection({ config: new ConnectionConfig(opts) });
+}
+
+module.exports = createConnection;
diff --git a/lib/create_pool.js b/lib/create_pool.js
new file mode 100644
index 0000000000..7f782aff9a
--- /dev/null
+++ b/lib/create_pool.js
@@ -0,0 +1,10 @@
+'use strict';
+
+const Pool = require('./pool.js');
+const PoolConfig = require('./pool_config.js');
+
+function createPool(config) {
+  return new Pool({ config: new PoolConfig(config) });
+}
+
+module.exports = createPool
diff --git a/lib/create_pool_cluster.js b/lib/create_pool_cluster.js
new file mode 100644
index 0000000000..4ded78b783
--- /dev/null
+++ b/lib/create_pool_cluster.js
@@ -0,0 +1,9 @@
+'use strict';
+
+const PoolCluster = require('./pool_cluster.js');
+
+function createPoolCluster(config) {
+  return new PoolCluster(config);
+}
+
+module.exports = createPoolCluster;
diff --git a/package.json b/package.json
index 07ab95d93f..b05dd0b628 100644
--- a/package.json
+++ b/package.json
@@ -43,7 +43,6 @@
     "typings/mysql",
     "index.js",
     "index.d.ts",
-    "common.js",
     "promise.js",
     "promise.d.ts"
   ],
diff --git a/promise.js b/promise.js
index 04eaff6433..32cd8dc4c2 100644
--- a/promise.js
+++ b/promise.js
@@ -1,12 +1,15 @@
 'use strict';
 
 const SqlString = require('sqlstring');
-const common = require('./common.js');
 const EventEmitter = require('events').EventEmitter;
 const parserCache = require('./lib/parsers/parser_cache.js');
 const PoolConnection = require('./lib/pool_connection.js');
 const Pool = require('./lib/pool.js');
 const PoolCluster = require('./lib/pool_cluster.js');
+const createConnection = require('./lib/create_connection.js');
+const Connection = require('./lib/connection.js');
+const createPool = require('./lib/create_pool.js');
+const createPoolCluster = require('./lib/create_pool_cluster.js');
 
 function makeDoneCb(resolve, reject, localErr) {
   return function (err, rows, fields) {
@@ -252,8 +255,8 @@ class PromiseConnection extends EventEmitter {
   }
 }
 
-function createConnection(opts) {
-  const coreConnection = common.createConnection(opts);
+function createConnectionPromise(opts) {
+  const coreConnection = createConnection(opts);
   const createConnectionErr = new Error();
   const thePromise = opts.Promise || Promise;
   if (!thePromise) {
@@ -290,12 +293,12 @@ function createConnection(opts) {
     const func = functionsToWrap[i];
 
     if (
-      typeof common.Connection.prototype[func] === 'function' &&
+      typeof Connection.prototype[func] === 'function' &&
       PromiseConnection.prototype[func] === undefined
     ) {
       PromiseConnection.prototype[func] = (function factory(funcName) {
         return function () {
-          return common.Connection.prototype[funcName].apply(
+          return Connection.prototype[funcName].apply(
             this.connection,
             arguments
           );
@@ -411,8 +414,8 @@ class PromisePool extends EventEmitter {
   }
 }
 
-function createPool(opts) {
-  const corePool = common.createPool(opts);
+function createPromisePool(opts) {
+  const corePool = createPool(opts);
   const thePromise = opts.Promise || Promise;
   if (!thePromise) {
     throw new Error(
@@ -545,8 +548,8 @@ class PromisePoolCluster extends EventEmitter {
   'add'
 ]);
 
-function createPoolCluster(opts) {
-  const corePoolCluster = common.createPoolCluster(opts);
+function createPromisePoolCluster(opts) {
+  const corePoolCluster = createPoolCluster(opts);
   const thePromise = (opts && opts.Promise) || Promise;
   if (!thePromise) {
     throw new Error(
@@ -558,9 +561,9 @@ function createPoolCluster(opts) {
   return new PromisePoolCluster(corePoolCluster, thePromise);
 }
 
-exports.createConnection = createConnection;
-exports.createPool = createPool;
-exports.createPoolCluster = createPoolCluster;
+exports.createConnection = createConnectionPromise;
+exports.createPool = createPromisePool;
+exports.createPoolCluster = createPromisePoolCluster;
 exports.escape = SqlString.escape;
 exports.escapeId = SqlString.escapeId;
 exports.format = SqlString.format;