From a90174c46bd494124760e86f64c2ea1f43989c50 Mon Sep 17 00:00:00 2001
From: MartinH <martinh@kentico.com>
Date: Thu, 14 Apr 2022 14:40:32 +0200
Subject: [PATCH] Reduce performance overhead of verbose logging

1) Log functions now accept function as an argument, which is lazily executed only when the particular logging level is actually enabled
2) Serialization of component tree in verbose logging is now done lazily using the above option
---
 src/lib/logging/EventStrategyLogger.js         |  4 ++--
 src/lib/logging/Logger.js                      | 12 +++++++++++-
 src/lib/matching/ActionResolver.js             |  2 +-
 src/lib/strategies/AbstractKeyEventStrategy.js |  6 +++---
 4 files changed, 17 insertions(+), 7 deletions(-)

diff --git a/src/lib/logging/EventStrategyLogger.js b/src/lib/logging/EventStrategyLogger.js
index d061931b..56a49217 100644
--- a/src/lib/logging/EventStrategyLogger.js
+++ b/src/lib/logging/EventStrategyLogger.js
@@ -16,14 +16,14 @@ class EventStrategyLogger extends Logger {
     this.verbose(
       this.nonKeyEventPrefix(componentId),
       'New component options:\n',
-      printComponent(componentOptions)
+      () => printComponent(componentOptions)
     );
   }
 
   logKeyHistory(keyHistory, componentId) {
     this.verbose(
       this.keyEventPrefix(componentId),
-      `Key history: ${printComponent(keyHistory.toJSON())}.`
+      () => `Key history: ${printComponent(keyHistory.toJSON())}.`
     );
   }
 }
diff --git a/src/lib/logging/Logger.js b/src/lib/logging/Logger.js
index 943aff36..d9240e19 100644
--- a/src/lib/logging/Logger.js
+++ b/src/lib/logging/Logger.js
@@ -66,7 +66,17 @@ class Logger {
         return;
       }
 
-      this[level] = ['debug', 'verbose'].indexOf(level) === -1 ? console[level] : console.log;
+      const logToConsole = ['debug', 'verbose'].indexOf(level) === -1 ? console[level] : console.log;
+
+      this[level] = (...args) => {
+        const materializedArgs = args.map(arg =>
+          // Function arguments are evaluated lazily to reduce performance overhead
+          typeof arg === 'function'
+            ? arg()
+            : arg
+        );
+        logToConsole(...materializedArgs);
+      }
     }
   }
 }
diff --git a/src/lib/matching/ActionResolver.js b/src/lib/matching/ActionResolver.js
index c7af8e0c..51b0590d 100644
--- a/src/lib/matching/ActionResolver.js
+++ b/src/lib/matching/ActionResolver.js
@@ -132,7 +132,7 @@ class ActionResolver {
       this.logger.verbose(
         this.logger.keyEventPrefix(componentId),
         'Internal key mapping:\n',
-        `${printComponent(keyHistoryMatcher.toJSON())}`
+        () => `${printComponent(keyHistoryMatcher.toJSON())}`
       );
 
       const keyHistory = this._eventStrategy.keyHistory;
diff --git a/src/lib/strategies/AbstractKeyEventStrategy.js b/src/lib/strategies/AbstractKeyEventStrategy.js
index a8ef1297..0914e729 100644
--- a/src/lib/strategies/AbstractKeyEventStrategy.js
+++ b/src/lib/strategies/AbstractKeyEventStrategy.js
@@ -149,7 +149,7 @@ class AbstractKeyEventStrategy {
     this.logger.verbose(
       this.logger.nonKeyEventPrefix(this.componentId, { focusTreeId: false }),
       'Registered component in application key map:\n',
-      `${printComponent(this.componentTree.get(this.componentId))}`
+      () => `${printComponent(this.componentTree.get(this.componentId))}`
     );
 
     return this.componentId;
@@ -176,7 +176,7 @@ class AbstractKeyEventStrategy {
     this.logger.verbose(
       this.logger.nonKeyEventPrefix(componentId),
       'Registered component mount:\n',
-      `${printComponent(this.componentTree.get(componentId))}`
+      () => `${printComponent(this.componentTree.get(componentId))}`
     );
   }
 
@@ -191,7 +191,7 @@ class AbstractKeyEventStrategy {
     this.logger.verbose(
       this.logger.nonKeyEventPrefix(componentId),
       'De-registered component. Remaining component Registry:\n',
-      `${printComponent(this.componentTree.toJSON())}`
+      () => `${printComponent(this.componentTree.toJSON())}`
     );
 
     if (this.componentTree.isRootId(componentId)) {