From 6c88392ea9487c9a53caa89804f6215ad960df87 Mon Sep 17 00:00:00 2001
From: Cristiano Aguzzi <relu91@users.noreply.github.com>
Date: Wed, 29 Nov 2023 21:22:46 +0100
Subject: [PATCH] fix(binding-modbus): clean up operations when timeout (#1173)

If we don't clean up the queue and the application is looping trying to
read modbus registers, the queue will grow indefinitely. This cleans up
the queue when a timeout occurs (e.g. wrong remote host or not reachable).
---
 packages/binding-modbus/src/modbus-connection.ts     | 12 +++++++-----
 .../binding-modbus/test/modbus-connection-test.ts    |  3 +++
 2 files changed, 10 insertions(+), 5 deletions(-)

diff --git a/packages/binding-modbus/src/modbus-connection.ts b/packages/binding-modbus/src/modbus-connection.ts
index 86f6cc92b..11509e55f 100644
--- a/packages/binding-modbus/src/modbus-connection.ts
+++ b/packages/binding-modbus/src/modbus-connection.ts
@@ -282,12 +282,14 @@ export class ModbusConnection {
                 this.trigger();
             } catch (error) {
                 warn("Cannot reconnect to modbus server");
-                // inform all the operations that the connection cannot be recovered
-                this.queue.forEach((transaction) => {
-                    transaction.operations.forEach((op) => {
-                        op.failed(error instanceof Error ? error : new Error(JSON.stringify(error)));
+                // inform and clean up all the operations that the connection cannot be recovered
+                while (this.queue.length > 0) {
+                    const transaction = this.queue.shift();
+                    // eslint-disable-next-line @typescript-eslint/no-non-null-assertion -- queue.length > 0
+                    transaction!.operations.forEach((operation) => {
+                        operation.failed(error instanceof Error ? error : new Error(JSON.stringify(error)));
                     });
-                });
+                }
             }
         } else if (this.client.isOpen && this.currentTransaction == null && this.queue.length > 0) {
             // take next transaction from queue and execute
diff --git a/packages/binding-modbus/test/modbus-connection-test.ts b/packages/binding-modbus/test/modbus-connection-test.ts
index b6f54c518..3f0562b7f 100644
--- a/packages/binding-modbus/test/modbus-connection-test.ts
+++ b/packages/binding-modbus/test/modbus-connection-test.ts
@@ -82,6 +82,8 @@ describe("Modbus connection", () => {
             connection.enqueue(op);
 
             await op.execute().should.eventually.be.rejected;
+            connection.queue.length.should.equal(0);
+
             connection.close();
         }).timeout(5000);
 
@@ -105,6 +107,7 @@ describe("Modbus connection", () => {
             connection.enqueue(op);
 
             await op.execute().should.eventually.be.rejected;
+            connection.queue.length.should.equal(0);
 
             connection.close();
         }).timeout(5000);