Send IDONTWANT prior to publish (#386)

Author: StefanBratanov

libp2p/src/main/kotlin/io/libp2p/pubsub/gossip/GossipParams.kt

@@ -242,7 +242,7 @@ data class GossipParams(
      * [iDontWantMinMessageSizeThreshold] controls the minimum size (in bytes) that an incoming message needs to be so that an IDONTWANT message is sent to mesh peers.
      * The default is 16 KB.
      */
-    val iDontWantMinMessageSizeThreshold: Int = 16000,
+    val iDontWantMinMessageSizeThreshold: Int = 16384,
 
     /**
      * [iDontWantTTL] Expiry time for cache of received IDONTWANT messages for peers

libp2p/src/main/kotlin/io/libp2p/pubsub/gossip/GossipRouter.kt

@@ -420,6 +420,7 @@ open class GossipRouter(
         mCache += msg
 
         return if (peers.isNotEmpty()) {
+            iDontWant(msg)
             val publishedMessages = peers
                 .filterNot { peerDoesNotWantMessage(it, msg.messageId) }
                 .map { submitPublishMessage(it, msg) }
@@ -610,15 +611,15 @@ open class GossipRouter(
         enqueueIwant(peer, messageIds)
     }
 
-    private fun iDontWant(msg: PubsubMessage, receivedFrom: PeerHandler) {
+    private fun iDontWant(msg: PubsubMessage, receivedFrom: PeerHandler? = null) {
         if (!this.protocol.supportsIDontWant()) return
         if (msg.protobufMessage.data.size() < params.iDontWantMinMessageSizeThreshold) return
         // we need to send IDONTWANT messages to mesh peers immediately in order for them to have an effect
         msg.topics
             .mapNotNull { mesh[it] }
             .flatten()
             .distinct()
-            .minus(receivedFrom)
+            .minus(setOfNotNull(receivedFrom))
             .forEach { sendIdontwant(it, msg.messageId) }
     }
 

libp2p/src/test/kotlin/io/libp2p/pubsub/gossip/GossipV1_2Tests.kt

@@ -150,6 +150,27 @@ class GossipV1_2Tests : GossipTestsBase() {
         assertThat(receivedMessages).containsExactly(msg.protobufMessage)
     }
 
+    @Test
+    fun iDontWantIsSentOnPublishing() {
+        val test = startSingleTopicNetwork(
+            params = GossipParams(iDontWantMinMessageSizeThreshold = 5),
+            mockRouterCount = 3
+        )
+
+        test.mockRouters.forEach { it.subscribe("topic1") }
+        val msgToPublish = newMessage("topic1", 0L, "Hello".toByteArray())
+        test.gossipRouter.publish(msgToPublish)
+        test.mockRouters.forEach {
+            // IDONTWANT is received
+            it.waitForMessage { msg ->
+                msg.control.idontwantCount == 1 &&
+                    msg.control.idontwantList.first().messageIDsList.map { mIds -> mIds.toWBytes() }.contains(msgToPublish.messageId)
+            }
+            // msg is received
+            it.waitForMessage { msg -> msg.publishCount > 0 }
+        }
+    }
+
     private fun startSingleTopicNetwork(params: GossipParams, mockRouterCount: Int): ManyRoutersTest {
         val test = ManyRoutersTest(
             protocol = PubsubProtocol.Gossip_V_1_2,