From 26150c77f19e61e85618f471e717e08a425dbbfd Mon Sep 17 00:00:00 2001
From: Szymon Sasin <szymon.sasin@gmail.com>
Date: Mon, 26 Aug 2024 11:22:11 +0300
Subject: [PATCH] Reuse coap-builder

---
 .../mbed/coap/server/CoapServerBuilder.java   | 14 +++++------
 .../coap/server/CoapServerBuilderTest.java    | 24 ++++++++++++++++++-
 2 files changed, 29 insertions(+), 9 deletions(-)

diff --git a/coap-core/src/main/java/com/mbed/coap/server/CoapServerBuilder.java b/coap-core/src/main/java/com/mbed/coap/server/CoapServerBuilder.java
index 40e5c0d4..539db44b 100644
--- a/coap-core/src/main/java/com/mbed/coap/server/CoapServerBuilder.java
+++ b/coap-core/src/main/java/com/mbed/coap/server/CoapServerBuilder.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2022-2023 java-coap contributors (https://github.com/open-coap/java-coap)
+ * Copyright (C) 2022-2024 java-coap contributors (https://github.com/open-coap/java-coap)
  * Copyright (C) 2011-2021 ARM Limited. All rights reserved.
  * SPDX-License-Identifier: Apache-2.0
  * Licensed under the Apache License, Version 2.0 (the "License");
@@ -137,7 +137,7 @@ public CoapServerBuilder maxIncomingBlockTransferSize(int size) {
         return this;
     }
 
-    private PutOnlyMap<CoapRequestId, CoapPacket> getOrCreateDuplicateDetectorCache() {
+    private PutOnlyMap<CoapRequestId, CoapPacket> getOrCreateDuplicateDetectorCache(ScheduledExecutorService scheduledExecutorService) {
         if (duplicateDetectionCache == null) {
             duplicateDetectionCache = new DefaultDuplicateDetectorCache("Default cache", duplicationMaxSize, scheduledExecutorService);
         }
@@ -210,11 +210,9 @@ public CoapServerBuilder requestTagSupplier(RequestTagSupplier requestTagSupplie
     public CoapServer build() {
         requireNonNull(coapTransport, "Missing transport");
         final boolean stopExecutor = scheduledExecutorService == null;
-        if (scheduledExecutorService == null) {
-            scheduledExecutorService = Executors.newSingleThreadScheduledExecutor();
-        }
+        final ScheduledExecutorService effectiveExecutorService = scheduledExecutorService != null ? scheduledExecutorService : Executors.newSingleThreadScheduledExecutor();
+        Timer timer = toTimer(effectiveExecutorService);
 
-        Timer timer = toTimer(scheduledExecutorService);
         Service<CoapPacket, Boolean> sender = packet -> coapTransport.sendPacket(packet)
                 .whenComplete((__, throwable) -> logSent(packet, throwable));
 
@@ -248,7 +246,7 @@ public CoapServer build() {
                 .then(sender);
 
         // INBOUND
-        PutOnlyMap<CoapRequestId, CoapPacket> duplicateDetectorCache = getOrCreateDuplicateDetectorCache();
+        PutOnlyMap<CoapRequestId, CoapPacket> duplicateDetectorCache = getOrCreateDuplicateDetectorCache(effectiveExecutorService);
         DuplicateDetector duplicateDetector = new DuplicateDetector(duplicateDetectorCache, duplicatedCoapMessageCallback);
         Service<CoapPacket, CoapPacket> inboundService = duplicateDetector
                 .andThen(new CoapRequestConverter(midSupplier))
@@ -271,7 +269,7 @@ public CoapServer build() {
             piggybackedExchangeFilter.stop();
             duplicateDetectorCache.stop();
             if (stopExecutor) {
-                scheduledExecutorService.shutdown();
+                effectiveExecutorService.shutdown();
             }
         });
 
diff --git a/coap-core/src/test/java/com/mbed/coap/server/CoapServerBuilderTest.java b/coap-core/src/test/java/com/mbed/coap/server/CoapServerBuilderTest.java
index 4d97618d..b336cdf2 100644
--- a/coap-core/src/test/java/com/mbed/coap/server/CoapServerBuilderTest.java
+++ b/coap-core/src/test/java/com/mbed/coap/server/CoapServerBuilderTest.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2022-2023 java-coap contributors (https://github.com/open-coap/java-coap)
+ * Copyright (C) 2022-2024 java-coap contributors (https://github.com/open-coap/java-coap)
  * Copyright (C) 2011-2021 ARM Limited. All rights reserved.
  * SPDX-License-Identifier: Apache-2.0
  * Licensed under the Apache License, Version 2.0 (the "License");
@@ -16,8 +16,11 @@
  */
 package com.mbed.coap.server;
 
+import static org.junit.jupiter.api.Assertions.assertNotNull;
 import static org.junit.jupiter.api.Assertions.assertThrows;
 import static org.mockito.Mockito.mock;
+import com.mbed.coap.client.CoapClient;
+import com.mbed.coap.transport.InMemoryCoapTransport;
 import java.time.Duration;
 import java.util.concurrent.ScheduledExecutorService;
 import org.junit.jupiter.api.Test;
@@ -55,4 +58,23 @@ public void shouldFail_whenIllegalTimeoutValue() throws Exception {
                 CoapServer.builder().responseTimeout(Duration.ofMillis(-1))
         );
     }
+
+    @Test
+    public void shouldReuseBuilder() throws Exception {
+        CoapServer server = new CoapServerBuilder()
+                .transport(InMemoryCoapTransport.create(5683))
+                .build().start();
+
+        CoapServerBuilder builder = CoapServer.builder()
+                .transport(InMemoryCoapTransport.create());
+
+
+        for (int i = 0; i < 3; i++) {
+            CoapClient client = builder.buildClient(server.getLocalSocketAddress());
+            assertNotNull(client.ping().get());
+            client.close();
+        }
+
+        server.stop();
+    }
 }