[fix] #1135 Never allow to loose all the WS2P connections

app/modules/ws2p/lib/WS2PCluster.ts

@@ -100,6 +100,7 @@ export class WS2PCluster {
   async headsReceived(heads:[{ message:string, sig:string }]) {
     const added:{ message:string, sig:string }[] = []
     await Promise.all(heads.map(async (h:{ message:string, sig:string }) => {
+      try {
         const message = h.message
         const sig = h.sig
         if (!message) {
@@ -178,6 +179,9 @@ export class WS2PCluster {
             throw "HEAD_MESSAGE_WRONGLY_SIGNED"
           }
         }
+      } catch (e) {
+        this.server.logger.trace(e)
+      }
     }))
     this.server.push({
       ws2p: 'heads',
@@ -339,6 +343,10 @@ export class WS2PCluster {
       // Trim the eventual extra connections
       setTimeout(() => this.trimClientConnections(), WS2PConstants.CONNEXION_TIMEOUT)
     }
+  }
+
+  listenServerFlow() {
+    let connectingToNodesByFlow = false
 
     // Also listen for network updates, and connect to new nodes
     this.server.pipe(es.mapSync((data:any) => {
@@ -375,6 +383,21 @@ export class WS2PCluster {
             this.server.logger.warn(e)
           }
         }
+
+        // WS2P disconnection
+        else if (data.ws2p === 'disconnected') {
+          const nbConnections = this.getAllConnections().length
+          if (nbConnections < WS2PConstants.CONNECTIONS_LOW_LEVEL && !connectingToNodesByFlow) {
+            try {
+              connectingToNodesByFlow = true
+              await this.connectToWS2Peers()
+            } catch (e) {
+              throw e
+            } finally {
+              connectingToNodesByFlow = false
+            }
+          }
+        }
       })()
 
       return data
@@ -594,6 +617,7 @@ export class WS2PCluster {
     // Pull blocks right on start
     const init = async () => {
       try {
+        await this.listenServerFlow()
         await this.connectToWS2Peers()
         await this.pullBlocks()
       } catch (e) {

app/modules/ws2p/lib/constants.ts

@@ -15,6 +15,7 @@ export const WS2PConstants = {
 
   MAX_LEVEL_1_PEERS: 10,
   MAX_LEVEL_2_PEERS: 10,
+  CONNECTIONS_LOW_LEVEL: 3,
 
   BAN_DURATION_IN_SECONDS: 120,
   ERROR_RECALL_DURATION_IN_SECONDS: 60,

test/integration/ws2p_heads.ts

@@ -82,10 +82,12 @@ describe("WS2P heads propagation", function() {
     })
   })
 
-  it('should be able to connect to s3 if the we increase size limit', async () => {
+  it('should be able to receive HEADs', async () => {
     b3 = s1.commit({ time: now })
-    await s2.waitToHaveBlock(3)
-    await s2.waitForHeads(1)
+    await Promise.all([
+      s2.waitToHaveBlock(3),
+      s2.waitForHeads(1)
+    ])
     await s1.expect('/network/ws2p/info', (res:any) => {
       assert.equal(res.peers.level1, 0)
       assert.equal(res.peers.level2, 1)