net: resend sync on peer disconnection.

lib/net/pool.js

@@ -173,7 +173,7 @@ Pool.prototype._init = function _init() {
   });
 
   this.chain.on('full', function() {
-    self.sync();
+    self.resync();
     self.emit('full');
     self.logger.info('Chain is fully synced (height=%d).', self.chain.height);
   });
@@ -686,44 +686,20 @@ Pool.prototype.startSync = function startSync() {
   assert(this.connected, 'Pool is not connected!');
 
   this.syncing = true;
-  this.sync();
+  this.resync(false);
 };
 
 /**
- * Send a sync to each peer.
- * @private
- */
-
-Pool.prototype.sync = function sync() {
-  var peer;
-
-  if (!this.syncing)
-    return;
-
-  for (peer = this.peers.head(); peer; peer = peer.next) {
-    if (!peer.outbound)
-      continue;
-    this.sendSync(peer);
-  }
-};
-
-/**
- * Force sending a sync to each peer.
- * @private
+ * Force sending of a sync to each peer.
  */
 
 Pool.prototype.forceSync = function forceSync() {
-  var peer;
-
-  if (!this.syncing)
+  if (!this.loaded)
     return;
 
-  for (peer = this.peers.head(); peer; peer = peer.next) {
-    if (!peer.outbound)
-      continue;
-    peer.syncing = false;
-    this.sendSync(peer);
-  }
+  assert(this.connected, 'Pool is not connected!');
+
+  this.resync(true);
 };
 
 /**
@@ -747,15 +723,43 @@ Pool.prototype.stopSync = function stopSync() {
 };
 
 /**
- * Start syncing from peer.
- * @method
- * @param {Peer} peer
+ * Send a sync to each peer.
+ * @private
+ * @param {Boolean?} force
  * @returns {Promise}
  */
 
-Pool.prototype.sendSync = co(function* sendSync(peer) {
-  var locator;
+Pool.prototype.resync = co(function* resync(force) {
+  var peer, locator;
 
+  if (!this.syncing)
+    return;
+
+  try {
+    locator = yield this.chain.getLocator();
+  } catch (e) {
+    this.emit('error', e);
+    return;
+  }
+
+  for (peer = this.peers.head(); peer; peer = peer.next) {
+    if (!peer.outbound)
+      continue;
+
+    if (!force && peer.syncing)
+      continue;
+
+    this.sendLocator(locator, peer);
+  }
+});
+
+/**
+ * Test whether a peer is sync-worthy.
+ * @param {Peer} peer
+ * @returns {Boolean}
+ */
+
+Pool.prototype.isSyncable = function isSyncable(peer) {
   if (!this.syncing)
     return false;
 
@@ -765,9 +769,6 @@ Pool.prototype.sendSync = co(function* sendSync(peer) {
   if (!peer.handshake)
     return false;
 
-  if (peer.syncing)
-    return false;
-
   if (!(peer.services & services.NETWORK))
     return false;
 
@@ -779,6 +780,54 @@ Pool.prototype.sendSync = co(function* sendSync(peer) {
       return false;
   }
 
+  return true;
+};
+
+/**
+ * Start syncing from peer.
+ * @method
+ * @param {Peer} peer
+ * @returns {Promise}
+ */
+
+Pool.prototype.sendSync = co(function* sendSync(peer) {
+  var locator;
+
+  if (peer.syncing)
+    return false;
+
+  if (!this.isSyncable(peer))
+    return false;
+
+  peer.syncing = true;
+  peer.blockTime = util.ms();
+
+  try {
+    locator = yield this.chain.getLocator();
+  } catch (e) {
+    peer.syncing = false;
+    peer.blockTime = -1;
+    this.emit('error', e);
+    return false;
+  }
+
+  return this.sendLocator(locator, peer);
+});
+
+/**
+ * Send a chain locator and start syncing from peer.
+ * @method
+ * @param {Hash[]} locator
+ * @param {Peer} peer
+ * @returns {Boolean}
+ */
+
+Pool.prototype.sendLocator = function sendLocator(locator, peer) {
+  var locator;
+
+  if (!this.isSyncable(peer))
+    return false;
+
   // Ask for the mempool if we're synced.
   if (this.network.requestMempool) {
     if (peer.loader && this.chain.synced)
@@ -788,16 +837,6 @@ Pool.prototype.sendSync = co(function* sendSync(peer) {
   peer.syncing = true;
   peer.blockTime = util.ms();
 
-  try {
-    locator = yield this.chain.getLocator();
-  } catch (e) {
-    this.emit('error', e);
-    return false;
-  }
-
-  if (peer.destroyed)
-    return false;
-
   if (this.checkpoints) {
     peer.sendGetHeaders(locator, this.headerTip.hash);
     return true;
@@ -806,7 +845,7 @@ Pool.prototype.sendSync = co(function* sendSync(peer) {
   peer.sendGetBlocks(locator);
 
   return true;
-});
+};
 
 /**
  * Send `mempool` to all peers.
@@ -1336,6 +1375,7 @@ Pool.prototype.handleOpen = co(function* handleOpen(peer) {
 Pool.prototype.handleClose = co(function* handleClose(peer, connected) {
   var outbound = peer.outbound;
   var loader = peer.loader;
+  var size = peer.requestMap.size;
 
   this.removePeer(peer);
 
@@ -1352,10 +1392,16 @@ Pool.prototype.handleClose = co(function* handleClose(peer, connected) {
   if (!this.loaded)
     return;
 
-  if (!outbound)
+  if (this.disconnecting)
     return;
 
-  if (this.disconnecting)
+  if (this.chain.synced && !loader && size > 0) {
+    this.logger.debug('Peer with requested blocks disconnected.');
+    this.logger.debug('Resending sync...');
+    this.forceSync();
+  }
+
+  if (!outbound)
     return;
 
   this.refill();