chain: add serial asynchronous "hooks".

lib/blockchain/chain.js

@@ -781,7 +781,7 @@ Chain.prototype.reorganizeSPV = co(function* reorganizeSPV(competitor, block) {
     entry = disconnect[i];
     headers = entry.toHeaders();
     view = new CoinView();
-    this.emit('disconnect', entry, headers, view);
+    yield this.fire('disconnect', entry, headers, view);
   }
 
   this.logger.warning(
@@ -825,7 +825,7 @@ Chain.prototype.disconnect = co(function* disconnect(entry) {
   this.height = prev.height;
 
   this.emit('tip', prev);
-  this.emit('disconnect', entry, block, view);
+  yield this.fire('disconnect', entry, block, view);
 });
 
 /**
@@ -874,7 +874,7 @@ Chain.prototype.reconnect = co(function* reconnect(entry) {
 
   this.emit('tip', entry);
   this.emit('reconnect', entry, block);
-  this.emit('connect', entry, block, result.view);
+  yield this.fire('connect', entry, block, result.view);
 });
 
 /**
@@ -941,7 +941,7 @@ Chain.prototype.setBestChain = co(function* setBestChain(entry, block, prev, fla
 
   this.emit('tip', entry);
   this.emit('block', block, entry);
-  this.emit('connect', entry, block, result.view);
+  yield this.fire('connect', entry, block, result.view);
 });
 
 /**
@@ -1040,7 +1040,7 @@ Chain.prototype._reset = co(function* reset(block, silent) {
   this.emit('tip', tip);
 
   if (!silent)
-    this.emit('reset', tip);
+    yield this.fire('reset', tip);
 
   // Reset the orphan map completely. There may
   // have been some orphans on a forked chain we

lib/node/fullnode.js

@@ -187,9 +187,9 @@ FullNode.prototype._init = function _init() {
     self.emit('tx', tx);
   });
 
-  this.chain.on('connect', co(function* (entry, block) {
+  this.chain.hook('connect', co(function* (entry, block) {
     try {
-      yield self.mempool.addBlock(entry, block.txs);
+      yield self.mempool._addBlock(entry, block.txs);
     } catch (e) {
       self.error(e);
     }
@@ -197,18 +197,18 @@ FullNode.prototype._init = function _init() {
     self.emit('connect', entry, block);
   }));
 
-  this.chain.on('disconnect', co(function* (entry, block) {
+  this.chain.hook('disconnect', co(function* (entry, block) {
     try {
-      yield self.mempool.removeBlock(entry, block.txs);
+      yield self.mempool._removeBlock(entry, block.txs);
     } catch (e) {
       self.error(e);
     }
     self.emit('disconnect', entry, block);
   }));
 
-  this.chain.on('reset', co(function* (tip) {
+  this.chain.hook('reset', co(function* (tip) {
     try {
-      yield self.mempool.reset();
+      yield self.mempool._reset();
     } catch (e) {
       self.error(e);
     }

lib/utils/asyncobject.js

@@ -6,11 +6,11 @@
 
 'use strict';
 
+var assert = require('assert');
+var EventEmitter = require('events').EventEmitter;
 var util = require('./util');
 var co = require('./co');
 var Lock = require('./lock');
-var assert = require('assert');
-var EventEmitter = require('events').EventEmitter;
 
 /**
  * An abstract object that handles state and
@@ -28,6 +28,7 @@ function AsyncObject() {
   EventEmitter.call(this);
 
   this._asyncLock = new Lock();
+  this._hooks = Object.create(null);
 
   this.loading = false;
   this.closing = false;
@@ -152,6 +153,81 @@ AsyncObject.prototype._close = function _close(callback) {
   throw new Error('Abstract method.');
 };
 
+/**
+ * Add a hook listener.
+ * @param {String} type
+ * @param {Function} handler
+ */
+
+AsyncObject.prototype.hook = function hook(type, handler) {
+  assert(typeof type === 'string', '`type` must be a string.');
+
+  if (!this._hooks[type])
+    this._hooks[type] = [];
+
+  this._hooks[type].push(handler);
+};
+
+/**
+ * Emit events and hooks for type.
+ * @method
+ * @param {String} type
+ * @param {...Object} args
+ * @returns {Promise}
+ */
+
+AsyncObject.prototype.fire = function fire() {
+  this.emit.apply(this, arguments);
+  return this.fireHook.apply(this, arguments);
+};
+
+/**
+ * Emit an asynchronous event (hook).
+ * Wait for promises to resolve.
+ * @method
+ * @param {String} type
+ * @param {...Object} args
+ * @returns {Promise}
+ */
+
+AsyncObject.prototype.fireHook = co(function* fireHook(type) {
+  var i, j, listeners, args, handler;
+
+  assert(typeof type === 'string', '`type` must be a string.');
+
+  listeners = this._hooks[type];
+
+  if (!listeners || listeners.length === 0)
+    return;
+
+  for (i = 0; i < listeners.length; i++) {
+    handler = listeners[i];
+
+    switch (arguments.length) {
+      case 1:
+        yield handler();
+        break;
+      case 2:
+        yield handler(arguments[1]);
+        break;
+      case 3:
+        yield handler(arguments[1], arguments[2]);
+        break;
+      case 4:
+        yield handler(arguments[1], arguments[2], arguments[3]);
+        break;
+      default:
+        if (!args) {
+          args = new Array(arguments.length - 1);
+          for (j = 1; j < arguments.length; j++)
+            args[j - 1] = arguments[j];
+        }
+        yield handler.apply(null, args);
+        break;
+    }
+  }
+});
+
 /*
  * Expose
  */