added an option to specify max number of requeues when connection clo…

…ses unexpectedly
ni-co · Feb 21, 2020 · 8a927f5 · 8a927f5
1 parent 54390ef
commit 8a927f5
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Showing 2 changed files with 55 additions and 13 deletions.
diff --git a/.vscode/settings.json b/.vscode/settings.json
@@ -0,0 +1,3 @@
+{
+  "eslint.enable": false
+}
diff --git a/lib/smtp-pool/index.js b/lib/smtp-pool/index.js
@@ -103,6 +103,7 @@ class SMTPPool extends EventEmitter {
 
         this._queue.push({
             mail,
+            requeueAttempts: 0,
             callback
         });
 
@@ -391,23 +392,16 @@ class SMTPPool extends EventEmitter {
 
             if (connection.queueEntry) {
                 // If the connection closed when sending, add the message to the queue again
+                // if max number of requeues is not reached yet
                 // Note that we must wait a bit.. because the callback of the 'error' handler might be called
                 // in the next event loop
                 setTimeout(() => {
                     if (connection.queueEntry) {
-                        this.logger.debug(
-                            {
-                                tnx: 'pool',
-                                cid: connection.id,
-                                messageId: connection.queueEntry.messageId,
-                                action: 'requeue'
-                            },
-                            'Re-queued message <%s> for #%s',
-                            connection.queueEntry.messageId,
-                            connection.id
-                        );
-                        this._queue.unshift(connection.queueEntry);
-                        connection.queueEntry = false;
+                        if (this._shouldRequeuOnConnectionClose(connection.queueEntry)) {
+                            this._requeueEntryOnConnectionClose(connection)
+                        } else {
+                            this._failDeliveryOnConnectionClose(connection);
+                        } 
                     }
                     this._continueProcessing();
                 }, 50);
@@ -421,6 +415,51 @@ class SMTPPool extends EventEmitter {
         return connection;
     }
 
+    _shouldRequeuOnConnectionClose(queueEntry) {
+      if (this.options.maxRequeues === undefined || this.options.maxRequeues < 0) {
+        return true;
+      }
+
+      return queueEntry.requeueAttempts && queueEntry.requeueAttempts < this.options.maxRequeues;
+    }
+
+    _failDeliveryOnConnectionClose(connection) {
+        if (connection.queueEntry && connection.queueEntry.callback) {
+            try {
+              connection.queueEntry.callback(new Error('Reached maximum number of retries after connection was closed'));
+            } catch (E) {
+                this.logger.error(
+                    {
+                        err: E,
+                        tnx: 'callback',
+                        messageId: connection.queueEntry.messageId,
+                        cid: connection.id
+                    },
+                    'Callback error for #%s: %s',
+                    connection.id,
+                    E.message
+                );
+            }
+            connection.queueEntry = false;
+        }
+    };
+
+    _requeueEntryOnConnectionClose(connection) {
+        this.logger.debug(
+            {
+                tnx: 'pool',
+                cid: connection.id,
+                messageId: connection.queueEntry.messageId,
+                action: 'requeue'
+            },
+            'Re-queued message <%s> for #%s',
+            connection.queueEntry.messageId,
+            connection.id
+        );
+        this._queue.unshift(connection.queueEntry);
+        connection.queueEntry = false;
+    }
+
     /**
      * Continue to process message if the pool hasn't closed
      */