util: access process states lazily in debuglog

`debuglog()` depends on `process.pid` and `process.env.NODE_DEBUG`,
so it needs to be called lazily in top scopes of internal modules
that may be loaded before these run time states are allowed to
be accessed. This patch makes its implementation lazy by default,
the process states are only accessed when the returned debug
function is called for the first time.

PR-URL: https://github.com/nodejs/node/pull/27281
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: Yongsheng Zhang <zyszys98@gmail.com>

1 files changed, 17 insertions, 1 deletions

diff --git a/lib/internal/util/debuglog.js b/lib/internal/util/debuglog.js
index e92f3ad2bd..11de25b6b4 100644
--- a/lib/internal/util/debuglog.js
+++ b/lib/internal/util/debuglog.js
@@ -31,7 +31,7 @@ function emitWarningIfNeeded(set) {
   }
 }
 
-function debuglog(set) {
+function debuglogImpl(set) {
   set = set.toUpperCase();
   if (!debugs[set]) {
     if (debugEnvRegex.test(set)) {
@@ -48,6 +48,22 @@ function debuglog(set) {
   return debugs[set];
 }
 
+// debuglogImpl depends on process.pid and process.env.NODE_DEBUG,
+// so it needs to be called lazily in top scopes of internal modules
+// that may be loaded before these run time states are allowed to
+// be accessed.
+function debuglog(set) {
+  let debug;
+  return function(...args) {
+    if (!debug) {
+      // Only invokes debuglogImpl() when the debug function is
+      // called for the first time.
+      debug = debuglogImpl(set);
+    }
+    debug(...args);
+  };
+}
+
 module.exports = {
   debuglog,
   initializeDebugEnv