Add explicit timeout to mysql DB queries

Author: mononaut

backend/mempool-config.sample.json

@@ -61,7 +61,8 @@
     "SOCKET": "/var/run/mysql/mysql.sock",
     "DATABASE": "mempool",
     "USERNAME": "mempool",
-    "PASSWORD": "mempool"
+    "PASSWORD": "mempool",
+    "TIMEOUT": 180000
   },
   "SYSLOG": {
     "ENABLED": true,

backend/src/__fixtures__/mempool-config.template.json

@@ -62,7 +62,8 @@
     "PORT": 18,
     "DATABASE": "__DATABASE_DATABASE__",
     "USERNAME": "__DATABASE_USERNAME__",
-    "PASSWORD": "__DATABASE_PASSWORD__"
+    "PASSWORD": "__DATABASE_PASSWORD__",
+    "TIMEOUT": "__DATABASE_TIMEOUT__"
   },
   "SYSLOG": {
     "ENABLED": false,

backend/src/__tests__/config.test.ts

@@ -72,7 +72,8 @@ describe('Mempool Backend Config', () => {
         PORT: 3306,
         DATABASE: 'mempool',
         USERNAME: 'mempool',
-        PASSWORD: 'mempool'
+        PASSWORD: 'mempool',
+        TIMEOUT: 180000,
       });
 
       expect(config.SYSLOG).toStrictEqual({

backend/src/config.ts

@@ -86,6 +86,7 @@ interface IConfig {
     DATABASE: string;
     USERNAME: string;
     PASSWORD: string;
+    TIMEOUT: number;
   };
   SYSLOG: {
     ENABLED: boolean;
@@ -194,7 +195,8 @@ const defaults: IConfig = {
     'PORT': 3306,
     'DATABASE': 'mempool',
     'USERNAME': 'mempool',
-    'PASSWORD': 'mempool'
+    'PASSWORD': 'mempool',
+    'TIMEOUT': 180000,
   },
   'SYSLOG': {
     'ENABLED': true,

backend/src/database.ts

@@ -33,8 +33,32 @@ import { FieldPacket, OkPacket, PoolOptions, ResultSetHeader, RowDataPacket } fr
     OkPacket[] | ResultSetHeader>(query, params?): Promise<[T, FieldPacket[]]>
   {
     this.checkDBFlag();
-    const pool = await this.getPool();
-    return pool.query(query, params);
+    let hardTimeout;
+    if (query?.timeout != null) {
+      hardTimeout = Math.floor(query.timeout * 1.1);
+    } else {
+      hardTimeout = config.DATABASE.TIMEOUT;
+    }
+    if (hardTimeout > 0) {
+      return new Promise((resolve, reject) => {
+        const timer = setTimeout(() => {
+          reject(new Error(`DB query failed to return, reject or time out within ${hardTimeout / 1000}s - ${query?.sql?.slice(0, 160) || (typeof(query) === 'string' || query instanceof String ? query?.slice(0, 160) : 'unknown query')}`));
+        }, hardTimeout);
+
+        this.getPool().then(pool => {
+          return pool.query(query, params) as Promise<[T, FieldPacket[]]>;
+        }).then(result => {
+          resolve(result);
+        }).catch(error => {
+          reject(error);
+        }).finally(() => {
+          clearTimeout(timer);
+        });
+      });
+    } else {
+      const pool = await this.getPool();
+      return pool.query(query, params);
+    }
   }
 
   public async checkDbConnection() {

docker/README.md

@@ -269,6 +269,7 @@ Corresponding `docker-compose.yml` overrides:
       DATABASE_DATABASE: ""
       DATABASE_USERNAME: ""
       DATABASE_PASSWORD: ""
+      DATABASE_TIMEOUT: ""
       ...
 ```
 

docker/backend/mempool-config.json

@@ -60,7 +60,8 @@
     "PORT": __DATABASE_PORT__,
     "DATABASE": "__DATABASE_DATABASE__",
     "USERNAME": "__DATABASE_USERNAME__",
-    "PASSWORD": "__DATABASE_PASSWORD__"
+    "PASSWORD": "__DATABASE_PASSWORD__",
+    "TIMEOUT": "__DATABASE_TIMEOUT__"
   },
   "SYSLOG": {
     "ENABLED": __SYSLOG_ENABLED__,

docker/backend/start.sh

@@ -64,6 +64,7 @@ __DATABASE_PORT__=${DATABASE_PORT:=3306}
 __DATABASE_DATABASE__=${DATABASE_DATABASE:=mempool}
 __DATABASE_USERNAME__=${DATABASE_USERNAME:=mempool}
 __DATABASE_PASSWORD__=${DATABASE_PASSWORD:=mempool}
+__DATABASE_TIMEOUT__=${DATABASE_TIMEOUT:=180000}
 
 # SYSLOG
 __SYSLOG_ENABLED__=${SYSLOG_ENABLED:=false}