From f4b74003c4d0257254a133f3d49e1cd25db04986 Mon Sep 17 00:00:00 2001
From: Buck Perley <buck@tierion.com>
Date: Thu, 6 Jun 2019 16:10:09 -0500
Subject: [PATCH] indexer: add ability to track listeners and remove them on
 close for indexer

---
 lib/indexer/indexer.js | 19 +++++++++++++------
 test/indexer-test.js   | 20 ++++++++++++++++++++
 2 files changed, 33 insertions(+), 6 deletions(-)

diff --git a/lib/indexer/indexer.js b/lib/indexer/indexer.js
index 33f45de9..3e1c6bc0 100644
--- a/lib/indexer/indexer.js
+++ b/lib/indexer/indexer.js
@@ -52,6 +52,7 @@ class Indexer extends EventEmitter {
 
     this.db = null;
     this.batch = null;
+    this.bound = [];
     this.syncing = false;
     this.height = 0;
   }
@@ -122,12 +123,17 @@ class Indexer extends EventEmitter {
   }
 
   /**
-   * Close the indexer, wait for the database to close.
+   * Close the indexer, wait for the database to close,
+   * unbind all events.
    * @returns {Promise}
    */
 
   async close() {
-    return this.db.close();
+    await this.db.close();
+    for (const [event, listener] of this.bound)
+      this.chain.removeListener(event, listener);
+
+    this.bound.length = 0;
   }
 
   /**
@@ -187,7 +193,7 @@ class Indexer extends EventEmitter {
   }
 
   /**
-   * Bind to chain events.
+   * Bind to chain events and save listeners for removal on close
    * @private
    */
 
@@ -202,9 +208,10 @@ class Indexer extends EventEmitter {
       }
     };
 
-    this.chain.on('connect', listener);
-    this.chain.on('disconnect', listener);
-    this.chain.on('reset', listener);
+    for (const event of ['connect', 'disconnect', 'reset']) {
+      this.bound.push([event, listener]);
+      this.chain.on(event, listener);
+    }
   }
 
   /**
diff --git a/test/indexer-test.js b/test/indexer-test.js
index 53aada2b..7785057d 100644
--- a/test/indexer-test.js
+++ b/test/indexer-test.js
@@ -4,6 +4,7 @@
 'use strict';
 
 const assert = require('bsert');
+const EventEmitter = require('events');
 const reorg = require('./util/reorg');
 const Script = require('../lib/script/script');
 const Opcode = require('../lib/script/opcode');
@@ -320,6 +321,25 @@ describe('Indexer', function() {
         message: 'Limit above max of 10.'
       });
     });
+
+    it('should track bound chain events and remove on close', async () => {
+      const indexer = new AddrIndexer({
+        blocks: {},
+        chain: new EventEmitter()
+      });
+
+      const events = ['connect', 'disconnect', 'reset'];
+
+      await indexer.open();
+
+      for (const event of events)
+        assert.equal(indexer.chain.listeners(event).length, 1);
+
+      await indexer.close();
+
+      for (const event of events)
+        assert.equal(indexer.chain.listeners(event).length, 0);
+    });
   });
 
   describe('Index 10 blocks', function() {