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⚡ Bolt: [성능 개선] StringBuilder 도입 및 Set을 통한 조회 성능 개선 #70

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⚡ Bolt: [성능 개선] StringBuilder 도입 및 Set을 통한 조회 성능 개선 #70

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3 changes: 3 additions & 0 deletions .jules/bolt.md
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Original file line number Diff line number Diff line change
@@ -1,3 +1,6 @@
## 2024-06-21 - Regex Compilation in Loops
**Learning:** In Kotlin, compiling regular expressions (`.toRegex()`) inside a loop over files is a significant O(N * M) performance bottleneck when processing ignore files (N files * M rules).
**Action:** Always map string rules to compiled `Regex` objects outside of the file iteration loop (O(M) compilation) to avoid unnecessary regex re-compilations.
## 2024-06-25 - Collection Lookup Performance in Loops
**Learning:** Checking for file exclusion (`in exclude`) inside a loop iterating over directory contents can be a significant bottleneck (O(N) lookup for each file) if the `exclude` collection is a `List`.
**Action:** Always prefer using `Set` (e.g., `mutableSetOf()`) over `List` for collections used primarily for lookup/containment checks inside loops, changing the lookup from O(N) to O(1).
16 changes: 8 additions & 8 deletions src/main/kotlin/html4tree/main.kt
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Original file line number Diff line number Diff line change
Expand Up @@ -54,19 +54,20 @@ fun String.urlEncodePath(): String {
return java.net.URLEncoder.encode(this, "UTF-8").replace("+", "%20")
}

fun process_ignore_file(curr_dir: File): List<String> {
fun process_ignore_file(curr_dir: File): Set<String> {

val ignore_filename = ".html4ignore"

val ignore_file_path = curr_dir.getAbsolutePath()+"/"+ignore_filename

val ignore_file = File(ignore_file_path)

val files_to_exclude = mutableListOf<String>()
val files_to_exclude = mutableSetOf<String>()

if(ignore_file.exists()){
val ignored_regexes = mutableListOf<Regex>()

// O(M) regex compilation outside of N files loop
ignore_file.forEachLine { ignored_regexes.add(("^"+it+"$").toRegex()) }

curr_dir.list().sorted().forEach {
Expand All @@ -79,15 +80,14 @@ fun process_ignore_file(curr_dir: File): List<String> {
}
}

if ("index.html" !in files_to_exclude)
files_to_exclude.add("index.html")
files_to_exclude.add("index.html") // Sets handle duplicates automatically, but no harm ensuring it's there

return files_to_exclude
}

fun process_dir(curr_dir: File){

val exclude: List<String> = process_ignore_file(curr_dir)
val exclude: Set<String> = process_ignore_file(curr_dir)

val css = """
<style>
Expand Down Expand Up @@ -126,7 +126,7 @@ fun process_dir(curr_dir: File){
"""

val index_middle = fun():String{
var l=""
val l = java.lang.StringBuilder()

val dir_files: MutableList<File> = curr_dir.listFiles()?.toMutableList() ?: mutableListOf()
dir_files.sortWith(compareBy ({it.name}) )
Expand All @@ -136,11 +136,11 @@ fun process_dir(curr_dir: File){
val fileName = it.getName()
val encodedHref = if (isLinkedDirectory) { "./${fileName.urlEncodePath()}/" } else { "./${fileName.urlEncodePath()}" }
val ariaLabel = "${fileName} ${if (isLinkedDirectory) { "디렉토리" } else { "파일" }}".escapeHtml()
l += """ <li><a style="display:block; width:100%" href="${encodedHref}" aria-label="${ariaLabel}">${if (isLinkedDirectory) { "&#128193;" } else { "&rtrif;" }} ${fileName.escapeHtml()}</a></li>"""+"\n"
l.append(""" <li><a style="display:block; width:100%" href="${encodedHref}" aria-label="${ariaLabel}">${if (isLinkedDirectory) { "&#128193;" } else { "&rtrif;" }} ${fileName.escapeHtml()}</a></li>"""+"\n")
}
}

return l;
return l.toString();
}

val index_bottom="""
Expand Down
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