From b3b5a0ca7466f76e9139f2f9409d5af4f42ea3f7 Mon Sep 17 00:00:00 2001
From: Joe Bateson <joe@joebateson.com>
Date: Thu, 24 Oct 2019 18:39:18 -0700
Subject: [PATCH] Cache getLocalAddress() to avoid per-request network address
 lookup (#454)

---
 packages/zipkin/src/InetAddress.js       | 9 +++++++--
 packages/zipkin/test/InetAddress.test.js | 4 ++++
 2 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/packages/zipkin/src/InetAddress.js b/packages/zipkin/src/InetAddress.js
index e52b7990..b332d6dd 100644
--- a/packages/zipkin/src/InetAddress.js
+++ b/packages/zipkin/src/InetAddress.js
@@ -31,7 +31,7 @@ class InetAddress {
 }
 
 // In non-node environments we fallback to 127.0.0.1
-InetAddress.getLocalAddress = function getLocalAddress() {
+function getLocalAddress() {
   const isNode = typeof process === 'object' && typeof process.on === 'function';
   if (!isNode) {
     return new InetAddress('127.0.0.1');
@@ -40,6 +40,11 @@ InetAddress.getLocalAddress = function getLocalAddress() {
   // eslint-disable-next-line global-require
   const networkAddress = require('./network');
   return new InetAddress(networkAddress.ipv4());
-};
+}
+
+// Cache this value at import time so as to avoid network interface
+// lookup on every call
+const cachedLocalAddress = getLocalAddress();
+InetAddress.getLocalAddress = () => cachedLocalAddress;
 
 module.exports = InetAddress;
diff --git a/packages/zipkin/test/InetAddress.test.js b/packages/zipkin/test/InetAddress.test.js
index 67a3bd1c..6f27195d 100644
--- a/packages/zipkin/test/InetAddress.test.js
+++ b/packages/zipkin/test/InetAddress.test.js
@@ -5,6 +5,10 @@ describe('InetAddress', () => {
     InetAddress.getLocalAddress();
   });
 
+  it('should return the same object reference for multiple calls (cached)', () => {
+    expect(InetAddress.getLocalAddress()).to.equal(InetAddress.getLocalAddress());
+  });
+
   it('should convert an IP address to integer representation', () => {
     const addr = new InetAddress('80.91.37.133');
     expect(addr.toInt()).to.equal(1348150661);