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>

9 files changed, 25 insertions, 51 deletions

diff --git a/lib/_stream_readable.js b/lib/_stream_readable.js
index 1b6f2175ce..34118f4fbe 100644
--- a/lib/_stream_readable.js
+++ b/lib/_stream_readable.js
@@ -30,14 +30,7 @@ const EE = require('events');
 const Stream = require('stream');
 const { Buffer } = require('buffer');
 
-let debuglog;
-function debug(...args) {
-  if (!debuglog) {
-    debuglog = require('internal/util/debuglog').debuglog('stream');
-  }
-  debuglog(...args);
-}
-
+const debug = require('internal/util/debuglog').debuglog('stream');
 const BufferList = require('internal/streams/buffer_list');
 const destroyImpl = require('internal/streams/destroy');
 const { getHighWaterMark } = require('internal/streams/state');
diff --git a/lib/internal/main/worker_thread.js b/lib/internal/main/worker_thread.js
index a06fda7a59..dd6a9426ff 100644
--- a/lib/internal/main/worker_thread.js
+++ b/lib/internal/main/worker_thread.js
@@ -44,6 +44,7 @@ const {
 } = require('internal/process/execution');
 
 const publicWorker = require('worker_threads');
+const debug = require('internal/util/debuglog').debuglog('worker');
 
 const assert = require('internal/assert');
 
@@ -51,8 +52,6 @@ patchProcessObject();
 setupInspectorHooks();
 setupDebugEnv();
 
-const debug = require('internal/util/debuglog').debuglog('worker');
-
 setupWarningHandler();
 
 // Since worker threads cannot switch cwd, we do not need to
diff --git a/lib/internal/modules/cjs/loader.js b/lib/internal/modules/cjs/loader.js
index 16940aa0c2..20ca6d113c 100644
--- a/lib/internal/modules/cjs/loader.js
+++ b/lib/internal/modules/cjs/loader.js
@@ -166,14 +166,7 @@ Object.defineProperty(Module, 'wrapper', {
   }
 });
 
-let debuglog;
-function debug(...args) {
-  if (!debuglog) {
-    debuglog = require('internal/util/debuglog').debuglog('module');
-  }
-  debuglog(...args);
-}
-
+const debug = require('internal/util/debuglog').debuglog('module');
 Module._debug = deprecate(debug, 'Module._debug is deprecated.', 'DEP0077');
 
 // Given a module name, and a list of paths to test, returns the first
diff --git a/lib/internal/stream_base_commons.js b/lib/internal/stream_base_commons.js
index 50eac42772..88896083f1 100644
--- a/lib/internal/stream_base_commons.js
+++ b/lib/internal/stream_base_commons.js
@@ -31,7 +31,7 @@ const kAfterAsyncWrite = Symbol('kAfterAsyncWrite');
 const kHandle = Symbol('kHandle');
 const kSession = Symbol('kSession');
 
-const debug = require('util').debuglog('stream');
+const debug = require('internal/util/debuglog').debuglog('stream');
 
 function handleWriteReq(req, data, encoding) {
   const { handle } = req;
diff --git a/lib/internal/timers.js b/lib/internal/timers.js
index aef099b4b9..566d7df036 100644
--- a/lib/internal/timers.js
+++ b/lib/internal/timers.js
@@ -107,13 +107,7 @@ const L = require('internal/linkedlist');
 const PriorityQueue = require('internal/priority_queue');
 
 const { inspect } = require('internal/util/inspect');
-let debuglog;
-function debug(...args) {
-  if (!debuglog) {
-    debuglog = require('internal/util/debuglog').debuglog('timer');
-  }
-  debuglog(...args);
-}
+const debug = require('internal/util/debuglog').debuglog('timer');
 
 // *Must* match Environment::ImmediateInfo::Fields in src/env.h.
 const kCount = 0;
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
diff --git a/lib/internal/worker.js b/lib/internal/worker.js
index 796d1713dd..e9d961f35a 100644
--- a/lib/internal/worker.js
+++ b/lib/internal/worker.js
@@ -48,14 +48,7 @@ const kOnErrorMessage = Symbol('kOnErrorMessage');
 const kParentSideStdio = Symbol('kParentSideStdio');
 
 const SHARE_ENV = Symbol.for('nodejs.worker_threads.SHARE_ENV');
-
-let debuglog;
-function debug(...args) {
-  if (!debuglog) {
-    debuglog = require('internal/util/debuglog').debuglog('worker');
-  }
-  debuglog(...args);
-}
+const debug = require('internal/util/debuglog').debuglog('worker');
 
 class Worker extends EventEmitter {
   constructor(filename, options = {}) {
diff --git a/lib/internal/worker/io.js b/lib/internal/worker/io.js
index 04f8f9ad59..8b7aedd39d 100644
--- a/lib/internal/worker/io.js
+++ b/lib/internal/worker/io.js
@@ -21,14 +21,7 @@ const {
 const { Readable, Writable } = require('stream');
 const EventEmitter = require('events');
 const { inspect } = require('internal/util/inspect');
-
-let debuglog;
-function debug(...args) {
-  if (!debuglog) {
-    debuglog = require('internal/util/debuglog').debuglog('worker');
-  }
-  debuglog(...args);
-}
+const debug = require('internal/util/debuglog').debuglog('worker');
 
 const kIncrementsPortRef = Symbol('kIncrementsPortRef');
 const kName = Symbol('kName');
diff --git a/lib/timers.js b/lib/timers.js
index 85801face5..ddce43e749 100644
--- a/lib/timers.js
+++ b/lib/timers.js
@@ -50,14 +50,7 @@ const {
   deprecate
 } = require('internal/util');
 const { ERR_INVALID_CALLBACK } = require('internal/errors').codes;
-
-let debuglog;
-function debug(...args) {
-  if (!debuglog) {
-    debuglog = require('internal/util/debuglog').debuglog('timer');
-  }
-  debuglog(...args);
-}
+const debug = require('internal/util/debuglog').debuglog('timer');
 
 const {
   destroyHooksExist,