From dd53e43958129331f72eff6866dda30aa2138cd5 Mon Sep 17 00:00:00 2001
From: Christopher Jeffrey <chjjeffrey@gmail.com>
Date: Sat, 27 Aug 2016 15:53:04 -0700
Subject: [PATCH] pool: repurpose regular peers if no loader is available.

---
 lib/net/peer.js |  12 ++---
 lib/net/pool.js | 114 ++++++++++++++++++++++++++++++------------------
 2 files changed, 78 insertions(+), 48 deletions(-)

diff --git a/lib/net/peer.js b/lib/net/peer.js
index b8017d2e..7f9aeedb 100644
--- a/lib/net/peer.js
+++ b/lib/net/peer.js
@@ -417,12 +417,6 @@ Peer.prototype._onAck = function _onAck(err) {
   // Start syncing the chain.
   this.sync();
 
-  // Ask for the mempool if we're synced.
-  if (this.network.requestMempool) {
-    if (this.isLoader() && this.chain.synced)
-      this.sendMempool();
-  }
-
   this.logger.debug('Received verack (%s).', this.hostname);
 
   // Finally we can let the pool know
@@ -2397,6 +2391,12 @@ Peer.prototype.sync = function sync(callback) {
       return;
   }
 
+  // Ask for the mempool if we're synced.
+  if (this.network.requestMempool) {
+    if (this.isLoader() && this.chain.synced)
+      this.sendMempool();
+  }
+
   this.syncSent = true;
 
   if (this.options.headers) {
diff --git a/lib/net/pool.js b/lib/net/pool.js
index 7bfc28d0..0405c385 100644
--- a/lib/net/pool.js
+++ b/lib/net/pool.js
@@ -275,20 +275,8 @@ Pool.prototype._init = function _init() {
   this.chain.on('full', function() {
     self.stopTimeout();
     self.stopInterval();
-
-    if (!self.chain.synced) {
-      // Ask loader for a mempool snapshot.
-      if (self.network.requestMempool) {
-        if (self.peers.load)
-          self.peers.load.sendMempool();
-      }
-
-      // Ask all peers for their latest blocks.
-      self.sync();
-    }
-
+    self.sync();
     self.emit('full');
-
     self.logger.info('Chain is fully synced (height=%d).', self.chain.height);
   });
 };
@@ -626,21 +614,16 @@ Pool.prototype.addLoader = function addLoader() {
   addr = this.getLoaderHost();
   peer = this.peers.get(addr);
 
+  if (peer) {
+    this.setLoader(peer);
+    return;
+  }
+
   if (this.syncing) {
     this.startTimeout();
     this.startInterval();
   }
 
-  if (peer) {
-    this.logger.info('Repurposing peer for loader (%s).', peer.hostname);
-    this.peers.repurpose(peer);
-    this.fillPeers();
-    utils.nextTick(function() {
-      self.emit('loader', peer);
-    });
-    return;
-  }
-
   peer = this.createPeer(addr);
 
   this.logger.info('Added loader peer (%s).', peer.hostname);
@@ -653,6 +636,33 @@ Pool.prototype.addLoader = function addLoader() {
   });
 };
 
+/**
+ * Add a loader peer. Necessary for
+ * a sync to even begin.
+ * @private
+ */
+
+Pool.prototype.setLoader = function setLoader(peer) {
+  var self = this;
+
+  if (!this.loaded)
+    return;
+
+  if (this.syncing) {
+    this.startTimeout();
+    this.startInterval();
+  }
+
+  this.logger.info('Repurposing peer for loader (%s).', peer.hostname);
+  this.peers.repurpose(peer);
+  this.fillPeers();
+  peer.sync();
+
+  utils.nextTick(function() {
+    self.emit('loader', peer);
+  });
+};
+
 /**
  * Start the blockchain sync.
  */
@@ -1029,6 +1039,18 @@ Pool.prototype.createPeer = function createPeer(addr, socket) {
   var self = this;
   var peer = new bcoin.peer(this, addr, socket);
 
+  peer.once('ack', function() {
+    if (!peer.outbound)
+      return;
+
+    // Attempt to promote from pending->regular
+    self.peers.promote(peer);
+
+    // If we don't have an ack'd loader yet, use this peer.
+    if (!self.peers.load || !self.peers.load.ack)
+      self.setLoader(peer);
+  });
+
   peer.once('close', function() {
     if (!self.loaded) {
       self.removePeer(peer);
@@ -1400,10 +1422,6 @@ Pool.prototype.addPeer = function addPeer() {
 
   this.peers.addPending(peer);
 
-  peer.once('ack', function() {
-    self.peers.promote(peer);
-  });
-
   utils.nextTick(function() {
     self.emit('peer', peer);
   });
@@ -1944,6 +1962,13 @@ function PeerList(pool) {
   this.map = {};
 }
 
+PeerList.prototype.addLoader = function addLoader(peer) {
+  this.load = peer;
+  this.all.push(peer);
+  assert(!this.map[peer.hostname]);
+  this.map[peer.hostname] = peer;
+};
+
 PeerList.prototype.addPending = function addPending(peer) {
   this.pending.push(peer);
   this.all.push(peer);
@@ -1951,6 +1976,13 @@ PeerList.prototype.addPending = function addPending(peer) {
   this.map[peer.hostname] = peer;
 };
 
+PeerList.prototype.addLeech = function addLeech(peer) {
+  this.leeches.push(peer);
+  this.all.push(peer);
+  assert(!this.map[peer.hostname]);
+  this.map[peer.hostname] = peer;
+};
+
 PeerList.prototype.promote = function promote(peer) {
   if (utils.binaryRemove(this.pending, peer, compare))
     utils.binaryInsert(this.regular, peer, compare);
@@ -1971,11 +2003,23 @@ PeerList.prototype.remove = function remove(peer) {
   }
 };
 
+PeerList.prototype.demoteLoader = function demoteLoader() {
+  var peer = this.load;
+  assert(peer);
+  this.load = null;
+  if (peer.ack)
+    utils.binaryInsert(this.regular, peer, compare);
+  else
+    utils.binaryInsert(this.pending, peer, compare);
+};
+
 PeerList.prototype.repurpose = function repurpose(peer) {
   var r1, r2;
 
   assert(peer.outbound);
-  assert(!this.load);
+
+  if (this.load)
+    this.demoteLoader();
 
   r1 = utils.binaryRemove(this.pending, peer, compare);
   r2 = utils.binaryRemove(this.regular, peer, compare);
@@ -1993,20 +2037,6 @@ PeerList.prototype.size = function size() {
   return this.regular.length + this.pending.length;
 };
 
-PeerList.prototype.addLeech = function addLeech(peer) {
-  this.leeches.push(peer);
-  this.all.push(peer);
-  assert(!this.map[peer.hostname]);
-  this.map[peer.hostname] = peer;
-};
-
-PeerList.prototype.addLoader = function addLoader(peer) {
-  this.load = peer;
-  this.all.push(peer);
-  assert(!this.map[peer.hostname]);
-  this.map[peer.hostname] = peer;
-};
-
 PeerList.prototype.get = function get(addr) {
   return this.map[addr.hostname];
 };