⚡ Bolt: 파일시스템 통계 조회 전 메모리 기반 필터링 선행 (성능 향상)

.jules/bolt.md

@@ -12,3 +12,4 @@
 ## 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.
+## 2026-07-10 - Expensive OS stat calls before cheap in-memory checks\n**Learning:** In Kotlin/Java, checking file properties (like `isDirectory` or `isSymbolicLink`) via `java.nio.file.Files` requires allocating `Path` objects and performs expensive native OS stat calls. When processing file listings, always short-circuit filesystem checks by testing against exclusion lists (using cheap in-memory string operations) before calling methods that touch the filesystem.\n**Action:** Re-ordered conditionals to check `exclude` sets before invoking `Files.isDirectory` and `Files.isSymbolicLink`.

src/main/kotlin/html4tree/main.kt

@@ -216,14 +216,17 @@ 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> ${fileName.escapeHtml()}</a></li>""")
-              l.append('\n')
+           val fileName = it.getName()
+           // ⚡ Bolt Performance Optimization: Short-circuit string match before expensive OS filesystem calls
+           if (fileName !in exclude) {
+               val isLinkedDirectory = Files.isDirectory(it.toPath(), LinkOption.NOFOLLOW_LINKS)
+               if ((isLinkedDirectory || !it.isDirectory()) && !Files.isSymbolicLink(it.toPath())) {
+                  val encodedHref = if (isLinkedDirectory) { "./${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')
+               }
            }
         }