chain: improve spv reorgs.

lib/chain/chain.js

@@ -760,7 +760,7 @@ Chain.prototype.reorganize = co(function* reorganize(competitor, block) {
   var connect = [];
   var i, entry;
 
-  assert(fork);
+  assert(fork, 'No free space or data corruption.');
 
   // Blocks to disconnect.
   entry = tip;
@@ -796,7 +796,8 @@ Chain.prototype.reorganize = co(function* reorganize(competitor, block) {
 });
 
 /**
- * Reorganize the blockchain for SPV.
+ * Reorganize the blockchain for SPV. This
+ * will reset the chain to the fork block.
  * @private
  * @param {ChainEntry} competitor - The competing chain's tip.
  * @param {Block|MerkleBlock} block - The being being added.
@@ -806,22 +807,32 @@ Chain.prototype.reorganize = co(function* reorganize(competitor, block) {
 Chain.prototype.reorganizeSPV = co(function* reorganizeSPV(competitor, block) {
   var tip = this.tip;
   var fork = yield this.findFork(tip, competitor);
-  var entry;
+  var disconnect = [];
+  var entry = tip;
+  var i;
 
-  assert(fork);
+  assert(fork, 'No free space or data corruption.');
 
-  // Blocks to disconnect.
+  // Buffer disconnected blocks.
-  entry = tip;
   while (entry.hash !== fork.hash) {
-    this.emit('disconnect', entry, entry.toHeaders());
+    disconnect.push(entry);
     entry = yield entry.getPrevious();
     assert(entry);
   }
 
   // Reset the main chain back
-  // to the fork block.
+  // to the fork block, causing
+  // us to redownload the blocks
+  // on the new main chain.
   yield this._reset(fork.hash);
 
+  // Emit disconnection events now that
+  // the chain has successfully reset.
+  for (i = 0; i < disconnect.length; i++) {
+    entry = disconnect[i];
+    this.emit('disconnect', entry, entry.toHeaders());
+  }
+
   this.emit('reorganize', block, tip.height, tip.hash);
 });
 
@@ -983,46 +994,40 @@ Chain.prototype.saveAlternate = co(function* saveAlternate(entry, block, prev) {
 });
 
 /**
- * Reset the chain to the desired height. This
+ * Reset the chain to the desired block. This
  * is useful for replaying the blockchain download
  * for SPV.
- * @param {Number} height
+ * @param {Hash|Number} block
  * @returns {Promise}
  */
 
-Chain.prototype.reset = co(function* reset(height) {
+Chain.prototype.reset = co(function* reset(block) {
   var unlock = yield this.locker.lock();
   try {
-    return yield this._reset(height);
+    return yield this._reset(block);
   } finally {
     unlock();
   }
 });
 
 /**
- * Reset the chain to the desired height without a lock.
+ * Reset the chain to the desired block without a lock.
  * @private
- * @param {Number} height
+ * @param {Hash|Number} block
  * @returns {Promise}
  */
 
-Chain.prototype._reset = co(function* reset(height) {
+Chain.prototype._reset = co(function* reset(block) {
-  var tip = yield this.db.reset(height);
+  var tip = yield this.db.reset(block);
-
-  this.synced = false;
 
+  // Reset state.
   this.tip = tip;
   this.height = tip.height;
-
   this.state = yield this.getDeploymentState();
+  this.synced = this.isFull(true);
 
   this.emit('tip', tip);
 
-  if (this.isFull()) {
-    this.synced = true;
-    this.emit('full');
-  }
-
   // Reset the orphan map completely. There may
   // have been some orphans on a forked chain we
   // no longer need.
@@ -1583,8 +1588,8 @@ Chain.prototype.getOrphan = function getOrphan(hash) {
  * @returns {Boolean}
  */
 
-Chain.prototype.isFull = function isFull() {
+Chain.prototype.isFull = function isFull(force) {
-  return !this.isInitial();
+  return !this.isInitial(force);
 };
 
 /**
@@ -1595,8 +1600,8 @@ Chain.prototype.isFull = function isFull() {
  * @returns {Boolean}
  */
 
-Chain.prototype.isInitial = function isInitial() {
+Chain.prototype.isInitial = function isInitial(force) {
-  if (this.synced)
+  if (!force && this.synced)
     return false;
 
   if (this.height < this.network.checkpoints.lastHeight)

lib/chain/chaindb.js

@@ -661,7 +661,7 @@ ChainDB.prototype.getEntries = function getEntries() {
   return this.db.values({
     gte: layout.e(constants.ZERO_HASH),
     lte: layout.e(constants.MAX_HASH),
-    parse: function(key, value) {
+    parse: function(value) {
       return ChainEntry.fromRaw(self.chain, value);
     }
   });
@@ -1229,34 +1229,34 @@ ChainDB.prototype.save = co(function* save(entry, block, view) {
 ChainDB.prototype._save = co(function* save(entry, block, view) {
   var hash = block.hash();
 
-  // Hash->height index
+  // Hash->height index.
   this.put(layout.h(hash), U32(entry.height));
 
-  // Entry data
+  // Entry data.
   this.put(layout.e(hash), entry.toRaw());
   this.cacheHash.push(entry.hash, entry);
 
-  // Tip index
+  // Tip index.
   this.del(layout.a(entry.prevBlock));
   this.put(layout.a(hash), DUMMY);
 
   if (!view) {
-    // Save block data
+    // Save block data.
     yield this.saveBlock(block);
     return;
   }
 
-  // Hash->next-block index
+  // Hash->next-block index.
   this.put(layout.n(entry.prevBlock), hash);
 
-  // Height->hash index
+  // Height->hash index.
   this.put(layout.H(entry.height), hash);
   this.cacheHeight.push(entry.height, entry);
 
-  // Connect block and save data
+  // Connect block and save data.
   yield this.saveBlock(block, view);
 
-  // New chain state
+  // Commit new chain state.
   this.put(layout.R, this.pending.commit(hash));
 });
 
@@ -1291,14 +1291,20 @@ ChainDB.prototype.reconnect = co(function* reconnect(entry, block, view) {
 ChainDB.prototype._reconnect = co(function* reconnect(entry, block, view) {
   var hash = block.hash();
 
+  // We can now add a hash->next-block index.
   this.put(layout.n(entry.prevBlock), hash);
-  this.put(layout.H(entry.height), hash);
 
-  this.cacheHash.push(entry.hash, entry);
+  // We can now add a height->hash index.
+  this.put(layout.H(entry.height), hash);
   this.cacheHeight.push(entry.height, entry);
 
+  // Re-insert into cache.
+  this.cacheHash.push(entry.hash, entry);
+
+  // Connect inputs.
   yield this.connectBlock(block, view);
 
+  // Update chain state.
   this.put(layout.R, this.pending.commit(hash));
 });
 
@@ -1335,9 +1341,11 @@ ChainDB.prototype.disconnect = co(function* disconnect(entry) {
 ChainDB.prototype._disconnect = co(function* disconnect(entry) {
   var block;
 
+  // Remove hash->next-block index.
   this.del(layout.n(entry.prevBlock));
-  this.del(layout.H(entry.height));
 
+  // Remove height->hash index.
+  this.del(layout.H(entry.height));
   this.cacheHeight.unpush(entry.height);
 
   block = yield this.getBlock(entry.hash);
@@ -1345,8 +1353,10 @@ ChainDB.prototype._disconnect = co(function* disconnect(entry) {
   if (!block)
     throw new Error('Block not found.');
 
+  // Disconnect inputs.
   yield this.disconnectBlock(block);
 
+  // Revert chain state to previous tip.
   this.put(layout.R, this.pending.commit(entry.prevBlock));
 
   return block;
@@ -1386,6 +1396,7 @@ ChainDB.prototype.reset = co(function* reset(block) {
   for (;;) {
     this.start();
 
+    // Stop once we hit our target tip.
     if (tip.hash === entry.hash) {
       this.put(layout.R, this.pending.commit(tip.hash));
       yield this.commit();
@@ -1394,14 +1405,18 @@ ChainDB.prototype.reset = co(function* reset(block) {
 
     assert(!tip.isGenesis());
 
+    // Revert the tip index.
     this.del(layout.a(tip.hash));
     this.put(layout.a(tip.prevBlock), DUMMY);
 
+    // Remove all records (including
+    // main-chain-only records).
     this.del(layout.H(tip.height));
     this.del(layout.h(tip.hash));
     this.del(layout.e(tip.hash));
     this.del(layout.n(tip.prevBlock));
 
+    // Disconnect and remove block data.
     try {
       yield this.removeBlock(tip.hash);
     } catch (e) {
@@ -1409,10 +1424,12 @@ ChainDB.prototype.reset = co(function* reset(block) {
       throw e;
     }
 
+    // Revert chain state to previous tip.
     this.put(layout.R, this.pending.commit(tip.prevBlock));
 
     yield this.commit();
 
+    // Update caches _after_ successful commit.
     this.cacheHeight.remove(tip.height);
     this.cacheHash.remove(tip.hash);
 
@@ -1432,17 +1449,29 @@ ChainDB.prototype.removeChains = co(function* removeChains() {
   var tips = yield this.getTips();
   var i;
 
-  for (i = 0; i < tips.length; i++)
+  // Note that this has to be
-    yield this.removeChain(tips[i]);
+  // one giant atomic write!
+  this.start();
+
+  try {
+    for (i = 0; i < tips.length; i++)
+      yield this._removeChain(tips[i]);
+  } catch (e) {
+    this.drop();
+    throw e;
+  }
+
+  yield this.commit();
 });
 
 /**
  * Remove an alternate chain.
+ * @private
  * @param {Hash} hash - Alternate chain tip.
  * @returns {Promise}
  */
 
-ChainDB.prototype.removeChain = co(function* removeChain(hash) {
+ChainDB.prototype._removeChain = co(function* removeChain(hash) {
   var tip = yield this.get(hash);
 
   if (!tip)
@@ -1450,27 +1479,25 @@ ChainDB.prototype.removeChain = co(function* removeChain(hash) {
 
   this.logger.debug('Removing alternate chain: %s.', tip.rhash);
 
-  this.start();
+  for (;;) {
-
-  while (tip) {
     if (yield tip.isMainChain())
       break;
 
     assert(!tip.isGenesis());
 
+    // Remove all non-main-chain records.
     this.del(layout.a(tip.hash));
     this.del(layout.h(tip.hash));
     this.del(layout.e(tip.hash));
     this.del(layout.b(tip.hash));
 
+    // Queue up hash to be removed
+    // on successful write.
     this.cacheHash.unpush(tip.hash);
 
     tip = yield this.get(tip.prevBlock);
+    assert(tip);
   }
-
-  yield this.commit();
-
-  return tip;
 });
 
 /**
@@ -1485,6 +1512,8 @@ ChainDB.prototype.saveBlock = co(function* saveBlock(block, view) {
   if (this.options.spv)
     return;
 
+  // Write actual block data (this may be
+  // better suited to flat files in the future).
   this.put(layout.b(block.hash()), block.toRaw());
 
   if (!view)