fix(mysql): release connection on deadlocks (#13102)

* test(mysql, mariadb): improve transaction tests

- Greatly improve test for `SELECT ... LOCK IN SHARE MODE`
- Greatly improve test for deadlock handling

* fix(mysql): release connection on deadlocks

This is a follow-up for a problem not covered by #12841.

* refactor(mariadb): `query.js` similar to mysql's

* Update comments with a reference to this PR

lib/dialects/mariadb/query.js

@@ -7,6 +7,7 @@ const DataTypes = require('../../data-types');
 const { logger } = require('../../utils/logger');
 
 const ER_DUP_ENTRY = 1062;
+const ER_DEADLOCK = 1213;
 const ER_ROW_IS_REFERENCED = 1451;
 const ER_NO_REFERENCED_ROW = 1452;
 
@@ -46,40 +47,25 @@ class Query extends AbstractQuery {
 
     try {
       results = await connection.query(this.sql, parameters);
-      complete();
-
-      // Log warnings if we've got them.
-      if (showWarnings && results && results.warningStatus > 0) {
-        await this.logWarnings(results);
-      }
-    } catch (err) {
-      // MariaDB automatically rolls-back transactions in the event of a
-      // deadlock.
-      //
-      // Even though we shouldn't need to do this, we initiate a manual
-      // rollback. Without the rollback, the next transaction using the
-      // connection seems to retain properties of the previous transaction
-      // (e.g. isolation level) and not work as expected.
-      //
-      // For example (in our tests), a follow-up READ_COMMITTED transaction
-      // doesn't work as expected unless we explicitly rollback the
-      // transaction: it would fail to read a value inserted outside of that
-      // transaction.
-      if (options.transaction && err.errno === 1213) {
+    } catch (error) {
+      if (options.transaction && error.errno === ER_DEADLOCK) {
+        // MariaDB automatically rolls-back transactions in the event of a deadlock.
+        // However, we still initiate a manual rollback to ensure the connection gets released - see #13102.
         try {
           await options.transaction.rollback();
-        } catch (err) {
+        } catch (error_) {
           // Ignore errors - since MariaDB automatically rolled back, we're
           // not that worried about this redundant rollback failing.
         }
+
         options.transaction.finished = 'rollback';
       }
 
+      error.sql = sql;
+      error.parameters = parameters;
+      throw this.formatError(error);
+    } finally {
       complete();
-
-      err.sql = sql;
-      err.parameters = parameters;
-      throw this.formatError(err);
     }
 
     if (showWarnings && results && results.warningStatus > 0) {

lib/dialects/mysql/query.js

@@ -6,6 +6,7 @@ const _ = require('lodash');
 const { logger } = require('../../utils/logger');
 
 const ER_DUP_ENTRY = 1062;
+const ER_DEADLOCK = 1213;
 const ER_ROW_IS_REFERENCED = 1451;
 const ER_NO_REFERENCED_ROW = 1452;
 
@@ -57,19 +58,27 @@ class Query extends AbstractQuery {
             .setMaxListeners(100);
         });
       }
-    } catch (err) {
-      // MySQL automatically rolls-back transactions in the event of a deadlock
-      if (options.transaction && err.errno === 1213) {
+    } catch (error) {
+      if (options.transaction && error.errno === ER_DEADLOCK) {
+        // MySQL automatically rolls-back transactions in the event of a deadlock.
+        // However, we still initiate a manual rollback to ensure the connection gets released - see #13102.
+        try {
+          await options.transaction.rollback();
+        } catch (error_) {
+          // Ignore errors - since MySQL automatically rolled back, we're
+          // not that worried about this redundant rollback failing.
+        }
+
         options.transaction.finished = 'rollback';
       }
 
-      err.sql = sql;
-      err.parameters = parameters;
-      throw this.formatError(err);
+      error.sql = sql;
+      error.parameters = parameters;
+      throw this.formatError(error);
+    } finally {
+      complete();
     }
 
-    complete();
-
     if (showWarnings && results && results.warningStatus > 0) {
       await this.logWarnings(results);
     }

package.json

@@ -80,6 +80,7 @@
     "nyc": "^15.0.0",
     "p-map": "^4.0.0",
     "p-props": "^4.0.0",
+    "p-settle": "^4.1.1",
     "p-timeout": "^4.0.0",
     "pg": "^8.2.1",
     "pg-hstore": "^2.x",

test/integration/replication.test.js

@@ -18,8 +18,8 @@ describe(Support.getTestDialectTeaser('Replication'), () => {
 
     this.sequelize = Support.getSequelizeInstance(null, null, null, {
       replication: {
-        write: Support.getConnectionOptions(),
-        read: [Support.getConnectionOptions()]
+        write: Support.getConnectionOptionsWithoutPool(),
+        read: [Support.getConnectionOptionsWithoutPool()]
       }
     });
 

test/support.js

@@ -2,6 +2,7 @@
 
 const fs = require('fs');
 const path = require('path');
+const { isDeepStrictEqual } = require('util');
 const _ = require('lodash');
 const Sequelize = require('../index');
 const Config = require('./config/config');
@@ -119,11 +120,10 @@ const Support = {
     return this.getSequelizeInstance(config.database, config.username, config.password, sequelizeOptions);
   },
 
-  getConnectionOptions() {
-    const config = Config[this.getTestDialect()];
-
+  getConnectionOptionsWithoutPool() {
+    // Do not break existing config object - shallow clone before `delete config.pool`
+    const config = { ...Config[this.getTestDialect()] };
     delete config.pool;
-
     return config;
   },
 
@@ -207,6 +207,10 @@ const Support = {
     return `[${dialect.toUpperCase()}] ${moduleName}`;
   },
 
+  getPoolMax() {
+    return Config[this.getTestDialect()].pool.max;
+  },
+
   expectsql(query, assertions) {
     const expectations = assertions.query || assertions;
     let expectation = expectations[Support.sequelize.dialect.name];
@@ -234,6 +238,10 @@ const Support = {
       const bind = assertions.bind[Support.sequelize.dialect.name] || assertions.bind['default'] || assertions.bind;
       expect(query.bind).to.deep.equal(bind);
     }
+  },
+
+  isDeepEqualToOneOf(actual, expectedOptions) {
+    return expectedOptions.some(expected => isDeepStrictEqual(actual, expected));
   }
 };