util: fix inspecting of proxy objects

In certain conditions, inspecting a Proxy object can lead to a
max call stack error. Avoid that by detecting the Proxy object
and outputting information about the Proxy object itself.

Fixes: https://github.com/nodejs/node/issues/6464
PR-URL: https://github.com/nodejs/node/pull/6465
Reviewed-By: Myles Borins <myles.borins@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>

1 files changed, 44 insertions, 0 deletions

diff --git a/benchmark/util/inspect-proxy.js b/benchmark/util/inspect-proxy.js
new file mode 100644
index 0000000000..92d5a9a47d
--- /dev/null
+++ b/benchmark/util/inspect-proxy.js
@@ -0,0 +1,44 @@
+'use strict';
+
+const util = require('util');
+const common = require('../common.js');
+
+const bench = common.createBenchmark(main, {
+  v: [1, 2],
+  n: [1e6]
+});
+
+function twoDifferentProxies(n) {
+  // This one should be slower between we're looking up multiple proxies.
+  const proxyA = new Proxy({}, {get: () => {}});
+  const proxyB = new Proxy({}, {get: () => {}});
+  bench.start();
+  for (var i = 0; i < n; i += 1)
+    util.inspect({a: proxyA, b: proxyB}, {showProxy: true});
+  bench.end(n);
+}
+
+function oneProxy(n) {
+  // This one should be a bit faster because of the internal caching.
+  const proxy = new Proxy({}, {get: () => {}});
+  bench.start();
+  for (var i = 0; i < n; i += 1)
+    util.inspect({a: proxy, b: proxy}, {showProxy: true});
+  bench.end(n);
+}
+
+function main(conf) {
+  const n = conf.n | 0;
+  const v = conf.v | 0;
+
+  switch (v) {
+    case 1:
+      oneProxy(n);
+      break;
+    case 2:
+      twoDifferentProxies(n);
+      break;
+    default:
+      throw new Error('Should not get to here');
+  }
+}