[CONJS-200] Improve pool connection error messaging

documentation/callback-api.md

@@ -331,6 +331,7 @@ Specific options for pools are :
 | **`acquireTimeout`** | Timeout to get a new connection from pool in ms. |*integer* | 10000 |
 | **`connectionLimit`** | Maximum number of connection in pool. |*integer* | 10 |
 | **`idleTimeout`** | Indicate idle time after which a pool connection is released. Value must be lower than [@@wait_timeout](https://mariadb.com/kb/en/library/server-system-variables/#wait_timeout). In seconds (0 means never release) |*integer* | 1800 |
+| **`initializationTimeout`** | Pool will retry creating connection in loop, emitting 'error' event when reaching this timeout. In milliseconds |*integer* | 30000 |
 | **`minimumIdle`** | Permit to set a minimum number of connection in pool. **Recommendation is to use fixed pool, so not setting this value**.|*integer* | *set to connectionLimit value* |
 | **`minDelayValidation`** | When asking a connection to pool, the pool will validate the connection state. "minDelayValidation" permits disabling this validation if the connection has been borrowed recently avoiding useless verifications in case of frequent reuse of connections. 0 means validation is done each time the connection is asked. (in ms) |*integer*| 500|
 | **`noControlAfterUse`** | After giving back connection to pool (connection.end) connector will reset or rollback connection to ensure a valid state. This option permit to disable those controls|*boolean*| false|
@@ -345,6 +346,7 @@ Specific options for pools are :
 | **`connection`** | This event is emitted when a new connection is added to the pool. Has a connection object parameter |
 | **`enqueue`** | This event is emitted when a command cannot be satisfied immediately by the pool and is queued. |
 | **`release`** | This event is emitted when a connection is released back into the pool. Has a connection object parameter|
+| **`error`** | When pool fails to create new connection after reaching `initializationTimeout` timeout |
 
 **Example:**
 

documentation/promise-api.md

@@ -360,6 +360,7 @@ Specific options for pools are :
 | **`acquireTimeout`** | Timeout to get a new connection from pool in ms. In order to have connection error information, must be higher than connectTimeout |*integer* | 10000 |
 | **`connectionLimit`** | Maximum number of connection in pool. |*integer* | 10 |
 | **`idleTimeout`** | Indicate idle time after which a pool connection is released. Value must be lower than [@@wait_timeout](https://mariadb.com/kb/en/library/server-system-variables/#wait_timeout). In seconds (0 means never release) |*integer* | 1800 |
+| **`initializationTimeout`** | Pool will retry creating connection in loop, emitting 'error' event when reaching this timeout. In milliseconds |*integer* | 30000 |
 | **`minimumIdle`** | Permit to set a minimum number of connection in pool. **Recommendation is to use fixed pool, so not setting this value**.|*integer* | *set to connectionLimit value* |
 | **`minDelayValidation`** | When asking a connection to pool, the pool will validate the connection state. "minDelayValidation" permits disabling this validation if the connection has been borrowed recently avoiding useless verifications in case of frequent reuse of connections. 0 means validation is done each time the connection is asked. (in ms) |*integer*| 500|
 | **`noControlAfterUse`** | After giving back connection to pool (connection.end) connector will reset or rollback connection to ensure a valid state. This option permit to disable those controls|*boolean*| false|
@@ -1362,6 +1363,7 @@ This is an alias for [`connection.escapeId(value) → String`](#connectionescape
 | **`connection`** | This event is emitted when a new connection is added to the pool. Has a connection object parameter |
 | **`enqueue`** | This event is emitted when a command cannot be satisfied immediately by the pool and is queued. |
 | **`release`** | This event is emitted when a connection is released back into the pool. Has a connection object parameter|
+| **`error`** | When pool fails to create new connection after reaching `initializationTimeout` timeout |
 
 **Example:**
 

lib/pool-callback.js

@@ -15,6 +15,7 @@ class PoolCallback extends EventEmitter {
     this.#pool.on('connection', this.emit.bind(this, 'connection'));
     this.#pool.on('enqueue', this.emit.bind(this, 'enqueue'));
     this.#pool.on('release', this.emit.bind(this, 'release'));
+    this.#pool.on('error', this.emit.bind(this, 'error'));
   }
 
   #noop = () => {};

lib/pool-promise.js

@@ -14,6 +14,7 @@ class PoolPromise extends EventEmitter {
     this.#pool.on('connection', this.emit.bind(this, 'connection'));
     this.#pool.on('enqueue', this.emit.bind(this, 'enqueue'));
     this.#pool.on('release', this.emit.bind(this, 'release'));
+    this.#pool.on('error', this.emit.bind(this, 'error'));
   }
 
   get closed() {

lib/pool.js

@@ -11,12 +11,14 @@ class Pool extends EventEmitter {
   #opts;
   #closed = false;
   #connectionInCreation = false;
+  #errorCreatingConnection = null;
   #idleConnections = new Queue();
   #activeConnections = {};
   #requests = new Queue();
   #unusedConnectionRemoverId;
   #requestTimeoutId;
   #connErrorNumber = 0;
+  #initialized = false;
   _sizeHandlerTimeout;
 
   constructor(options) {
@@ -231,6 +233,8 @@ class Pool extends EventEmitter {
             this._doCreateConnection(resolve, reject, timeoutEnd);
           })
             .then(() => {
+              this.#initialized = true;
+              this.#errorCreatingConnection = null;
               this.#connErrorNumber = 0;
               if (this._shouldCreateMoreConnections()) {
                 this.emit('validateSize');
@@ -239,25 +243,26 @@ class Pool extends EventEmitter {
             })
             .catch((err) => {
               this.#connectionInCreation = false;
-              if (this.totalConnections() === 0) {
-                const task = this.#requests.shift();
-                if (task) {
-                  this._rejectTask(task, err);
+              if (!this.#closed) {
+                if (!this.#initialized) {
+                  err.message = 'Error during pool initialization: ' + err.message;
+                } else {
+                  err.message = 'Pool fails to create connection: ' + err.message;
                 }
-              } else if (!this.#closed) {
-                console.error(`pool fail to create connection (${err.message})`);
+                this.#errorCreatingConnection = err;
+                this.emit('error', err);
+
+                //delay next try
+                this._sizeHandlerTimeout = setTimeout(
+                  function () {
+                    this._sizeHandlerTimeout = null;
+                    if (!this.#requests.isEmpty()) {
+                      this._sizeHandler();
+                    }
+                  }.bind(this),
+                  Math.min(++this.#connErrorNumber * 500, 10000)
+                );
               }
-
-              //delay next try
-              this._sizeHandlerTimeout = setTimeout(
-                function () {
-                  this._sizeHandlerTimeout = null;
-                  if (!this.#requests.isEmpty()) {
-                    this._sizeHandler();
-                  }
-                }.bind(this),
-                Math.min(++this.#connErrorNumber * 500, 10000)
-              );
             });
         }.bind(this)
       );
@@ -330,14 +335,18 @@ class Pool extends EventEmitter {
     while ((request = this.#requests.peekFront())) {
       if (request.timeout <= currTime) {
         this.#requests.shift();
-        request.reject(
-          Errors.createError(
-            `retrieve connection from pool timeout after ${Math.abs(
-              Date.now() - (request.timeout - this.#opts.acquireTimeout)
-            )}ms`,
-            Errors.ER_GET_CONNECTION_TIMEOUT
-          )
-        );
+        // if no connection and connections fails with error, throw connection error,
+        // else just a timeout error indicating that no connection was available until reaching timeout
+        let err =
+          this.activeConnections() == 0 && this.#errorCreatingConnection
+            ? this.#errorCreatingConnection
+            : Errors.createError(
+                `retrieve connection from pool timeout after ${Math.abs(
+                  Date.now() - (request.timeout - this.#opts.acquireTimeout)
+                )}ms`,
+                Errors.ER_GET_CONNECTION_TIMEOUT
+              );
+        request.reject(err);
       } else {
         this.#requestTimeoutId = setTimeout(this._requestTimeoutHandler.bind(this), request.timeout - currTime);
         return;

test/integration/test-pool-callback.js

@@ -12,6 +12,7 @@ describe('Pool callback', () => {
 
   it('pool with wrong authentication', function (done) {
     this.timeout(10000);
+    const initTime = Date.now();
     const pool = base.createPoolCallback({
       acquireTimeout: 4000,
       initializationTimeout: 2000,
@@ -21,6 +22,7 @@ describe('Pool callback', () => {
       if (!err) {
         done(new Error('must have thrown error'));
       } else {
+        assert(Date.now() - initTime >= 3980, 'expected > 4s, but was ' + (Date.now() - initTime));
         pool.query('SELECT 3', (err) => {
           if (!err) {
             done(new Error('must have thrown error'));
@@ -44,6 +46,54 @@ describe('Pool callback', () => {
       if (!err) {
         done(new Error('must have thrown error'));
       }
+      assert(Date.now() - initTime >= 3980, 'expected > 4s, but was ' + (Date.now() - initTime));
+    });
+  });
+
+  it('pool error event', async function () {
+    if (process.env.srv === 'maxscale' || process.env.srv === 'skysql-ha') this.skip(); //to avoid host being blocked
+    this.timeout(10000);
+    const pool = base.createPoolCallback({
+      acquireTimeout: 4000,
+      initializationTimeout: 2000,
+      user: 'wrongAuthentication'
+    });
+
+    await new Promise(function (resolver, rejecter) {
+      pool.on('error', (err) => {
+        assert.isTrue(err.message.includes('Error during pool initialization:'));
+        assert.isTrue(
+          err.errno === 1524 ||
+            err.errno === 1045 ||
+            err.errno === 1698 ||
+            err.errno === 45028 ||
+            err.errno === 45025 ||
+            err.errno === 45044,
+          err.message
+        );
+        pool.end();
+        resolver();
+      });
+    });
+  });
+
+  it('pool error fail connection', async function () {
+    if (process.env.srv === 'maxscale' || process.env.srv === 'skysql-ha') this.skip(); //to avoid host being blocked
+    this.timeout(10000);
+    const initTime = Date.now();
+    const pool = base.createPoolCallback({
+      acquireTimeout: 4000,
+      initializationTimeout: 2000,
+      host: 'wronghost'
+    });
+
+    await new Promise(function (resolver, rejecter) {
+      pool.on('error', (err) => {
+        assert(Date.now() - initTime >= 1980, 'expected > 2s, but was ' + (Date.now() - initTime));
+        assert.isTrue(err.message.includes('Error during pool initialization:'));
+        pool.end();
+        resolver();
+      });
     });
   });
 

test/integration/test-pool.js

@@ -187,17 +187,21 @@ describe('Pool', () => {
   it('pool with wrong authentication', async function () {
     if (process.env.srv === 'maxscale' || process.env.srv === 'skysql-ha') this.skip(); //to avoid host being blocked
     this.timeout(10000);
+    const initTime = Date.now();
     const pool = base.createPool({
       acquireTimeout: 4000,
       initializationTimeout: 2000,
       user: 'wrongAuthentication'
     });
+
     setTimeout(async () => {
       try {
         await pool.query('SELECT 2');
         pool.end();
         throw new Error('must have thrown error');
       } catch (err) {
+        assert(Date.now() - initTime >= 3980, 'expected > 4s, but was ' + (Date.now() - initTime));
+        assert.isTrue(err.message.includes('Error during pool initialization:'));
         assert.isTrue(
           err.errno === 1524 ||
             err.errno === 1045 ||
@@ -214,6 +218,8 @@ describe('Pool', () => {
       await pool.end();
       throw new Error('must have thrown error');
     } catch (err) {
+      assert(Date.now() - initTime >= 3980, 'expected > 4s, but was ' + (Date.now() - initTime));
+      assert.isTrue(err.message.includes('Error during pool initialization:'));
       assert.isTrue(
         err.errno === 1524 ||
           err.errno === 1045 ||
@@ -227,6 +233,8 @@ describe('Pool', () => {
         await pool.query('SELECT 3');
         throw new Error('must have thrown error');
       } catch (err) {
+        assert(Date.now() - initTime >= 3980, 'expected > 4s, but was ' + (Date.now() - initTime));
+        assert.isTrue(err.message.includes('Error during pool initialization:'));
         assert.isTrue(
           err.errno === 1524 ||
             err.errno === 1045 ||
@@ -242,6 +250,53 @@ describe('Pool', () => {
     }
   });
 
+  it('pool error event', async function () {
+    if (process.env.srv === 'maxscale' || process.env.srv === 'skysql-ha') this.skip(); //to avoid host being blocked
+    this.timeout(10000);
+    const pool = base.createPool({
+      acquireTimeout: 4000,
+      initializationTimeout: 2000,
+      user: 'wrongAuthentication'
+    });
+
+    await new Promise(function (resolver, rejecter) {
+      pool.on('error', (err) => {
+        assert.isTrue(err.message.includes('Error during pool initialization:'));
+        assert.isTrue(
+          err.errno === 1524 ||
+            err.errno === 1045 ||
+            err.errno === 1698 ||
+            err.errno === 45028 ||
+            err.errno === 45025 ||
+            err.errno === 45044,
+          err.message
+        );
+        pool.end();
+        resolver();
+      });
+    });
+  });
+
+  it('pool error fail connection', async function () {
+    if (process.env.srv === 'maxscale' || process.env.srv === 'skysql-ha') this.skip(); //to avoid host being blocked
+    this.timeout(10000);
+    const initTime = Date.now();
+    const pool = base.createPool({
+      acquireTimeout: 4000,
+      initializationTimeout: 2000,
+      host: 'wronghost'
+    });
+
+    await new Promise(function (resolver, rejecter) {
+      pool.on('error', (err) => {
+        assert(Date.now() - initTime >= 1980, 'expected > 2s, but was ' + (Date.now() - initTime));
+        assert.isTrue(err.message.includes('Error during pool initialization:'));
+        pool.end();
+        resolver();
+      });
+    });
+  });
+
   it('pool with wrong authentication connection', async function () {
     if (process.env.srv === 'maxscale' || process.env.srv === 'skysql' || process.env.srv === 'skysql-ha') this.skip();
     this.timeout(10000);