⚡ Bolt: [성능 개선] 파일 시스템 I/O 최소화 및 루프 최적화

.jules/bolt.md

@@ -12,3 +12,6 @@
 ## 2024-07-08 - URL Encoding String Allocation Bottleneck
 **Learning:** `byte.toString(16).padStart(2, '0').toUpperCase()` inside a loop allocating up to 3 strings per reserved byte in a hot path causes significant GC pressure. This is a common but dangerous anti-pattern in Kotlin when processing large strings or numerous files in directory crawlers.
 **Action:** Replace chained string operations with direct character mapping and bitwise operations (`ushr`, `and`) when building formatted hex output, which avoids intermediate string creation entirely. Ensure 100% branch coverage with test inputs spanning both < 10 and > 9 hex values.
+## 2024-07-09 - Short-circuiting File IO Operations and Avoiding Repeated Allocations
+**Learning:** In Kotlin/Java, checking file properties (like `isDirectory` or `isSymbolicLink`) via `java.nio.file.Files` requires allocating `Path` objects (via `toPath()`) and performs expensive native OS stat calls. When processing a directory listing, performing these IO operations before checking if the file is excluded creates significant overhead.
+**Action:** Always short-circuit filesystem checks by testing against exclusion lists (using cheap in-memory operations like `name` access) BEFORE calling methods that touch the filesystem. Additionally, cache the result of `toPath()` in a local variable if it needs to be used multiple times for the same file.

src/main/kotlin/html4tree/main.kt

@@ -139,13 +139,16 @@ fun process_ignore_file(curr_dir: File): Set<String> {
            }
        }
 
-       curr_dir.list()?.sorted()?.forEach {
+       // ⚡ Bolt Performance Optimization: Remove sorting and add early exit
+       // Sorting is unnecessary for a set, and we can stop regex matching once a match is found.
+       curr_dir.list()?.forEach {
            val current = it
-           ignored_regexes.forEach { regex ->
+           for (regex in ignored_regexes) {
               if(regex.matches(current)){
                  files_to_exclude.add(current)
+                 break
               }
-         }
+           }
        }
     }
 
@@ -225,14 +228,19 @@ fun process_dir(curr_dir: File){
         val dir_files: MutableList<File> = curr_dir.listFiles()?.toMutableList() ?: mutableListOf()
         dir_files.sortWith(compareBy ({it.name}) )
         dir_files.forEach {
-           val isLinkedDirectory = Files.isDirectory(it.toPath(), LinkOption.NOFOLLOW_LINKS)
-           if((it.getName() !in exclude) && (isLinkedDirectory || !it.isDirectory()) && !Files.isSymbolicLink(it.toPath())) {
-              val fileName = it.getName()
-              val encodedHref = if (isLinkedDirectory) { "./${fileName.urlEncodePath()}/" } else { "./${fileName.urlEncodePath()}" }
-              val ariaLabel = "${fileName} ${if (isLinkedDirectory) { "디렉토리" } else { "파일" }}".escapeHtml()
-              val icon = if (isLinkedDirectory) { "&#128193;" } else { "&rtrif;" }
-              l.append("""          <li><a style="display:block; width:100%" href="${encodedHref}" aria-label="${ariaLabel}"><span aria-hidden="true">${icon}</span> ${fileName.escapeHtml()}</a></li>""")
-              l.append('\n')
+           val fileName = it.getName()
+           if (fileName !in exclude) {
+              // ⚡ Bolt Performance Optimization: Short-circuit file system calls
+              // Only call toPath() and query file system properties if the file is not excluded.
+              val path = it.toPath()
+              val isLinkedDirectory = Files.isDirectory(path, LinkOption.NOFOLLOW_LINKS)
+              if((isLinkedDirectory || !it.isDirectory()) && !Files.isSymbolicLink(path)) {
+                 val encodedHref = if (isLinkedDirectory) { "./${fileName.urlEncodePath()}/" } else { "./${fileName.urlEncodePath()}" }
+                 val ariaLabel = "${fileName} ${if (isLinkedDirectory) { "디렉토리" } else { "파일" }}".escapeHtml()
+                 val icon = if (isLinkedDirectory) { "&#128193;" } else { "&rtrif;" }
+                 l.append("""          <li><a style="display:block; width:100%" href="${encodedHref}" aria-label="${ariaLabel}"><span aria-hidden="true">${icon}</span> ${fileName.escapeHtml()}</a></li>""")
+                 l.append('\n')
+              }
            }
         }