Improve allocation pattern

src/file/list_dir.odin

@@ -1,5 +1,6 @@
 package file
 
+import "base:runtime"
 import "core:fmt"
 import "core:os"
 import "core:strings"
@@ -7,40 +8,56 @@ import "core:strings"
 // -----------------------------------------
 
 DirectoryEntry :: struct #all_or_none {
-	relpath: string,
+	relpath: string, // NOTE: owning string
 	size:    i64,
 }
 
 // -----------------------------------------
 
-list_dir_recursive :: proc(f: ^os.File) -> [dynamic]DirectoryEntry {
+// Returning `[dynamic]DirectoryEntry` and each relpath `string` inside it are owned by the caller.
+list_dir_recursive :: proc(
+	f: ^os.File,
+	allocator := context.allocator,
+) -> [dynamic]DirectoryEntry {
 	path := os.name(f)
-	return list_dir_recursive_by_path_impl(path)
+	return list_dir_recursive_by_path_impl(path, allocator)
 }
 
-list_dir_recursive_by_path :: proc(path: string) -> [dynamic]DirectoryEntry {
-	return list_dir_recursive_by_path_impl(path)
+// Returning `[dynamic]DirectoryEntry` and each relpath `string` inside it are owned by the caller.
+list_dir_recursive_by_path :: proc(
+	path: string,
+	allocator := context.allocator,
+) -> [dynamic]DirectoryEntry {
+	return list_dir_recursive_by_path_impl(path, allocator)
 }
 
 @(private)
 list_dir_recursive_by_path_impl :: proc(
 	path: string,
+	allocator: runtime.Allocator
 ) -> [dynamic]DirectoryEntry {
 	if !os.is_dir(path) {
 		fmt.eprintln("error: path is not a directory:", path)
 		os.exit(1)
 	}
 
-	result := [dynamic]DirectoryEntry{}
+	working_dir, wd_err := os.get_working_directory(allocator)
+	if wd_err != nil {
+		fmt.eprintln("error: get working directory failed:", wd_err)
+		os.exit(1)
+	}
+	defer delete(working_dir, allocator)
 
-	queue := [dynamic]string{}
-	append(&queue, path)
+	result := make([dynamic]DirectoryEntry, allocator)
+
+	queue := make([dynamic]string, 0, 1, allocator) // reserve 1 slot
+	defer delete(queue) // dynamic array embeds allocator
+	append(&queue, strings.clone(path))
 
 	for len(queue) > 0 {
-		list_dir_queue(&queue, &result)
+		list_dir_queue(&queue, &result, working_dir, allocator)
 	}
 
-	shrink(&result, len(result)) // shrink to fit
 	return result
 }
 
@@ -48,10 +65,13 @@ list_dir_recursive_by_path_impl :: proc(
 list_dir_queue :: proc(
 	queue: ^[dynamic]string,
 	result: ^[dynamic]DirectoryEntry,
+	working_dir: string,
+	allocator: runtime.Allocator,
 ) {
 	assert(len(queue) > 0, "queue must not be empty")
 
 	path := pop(queue)
+	defer delete(path, queue^.allocator)
 
 	f, open_err := os.open(path, {.Read})
 	if open_err != nil {
@@ -60,41 +80,38 @@ list_dir_queue :: proc(
 	}
 	defer os.close(f)
 
-	entries, read_err := os.read_all_directory(f, context.allocator)
+	entries, read_err := os.read_all_directory(f, allocator)
 	if read_err != nil {
 		fmt.eprintln("error: read directory failed:", read_err)
 		os.exit(1)
 	}
-	defer delete(entries)
+	defer delete(entries, allocator)
 
-	// Reserve space for new entries
-	reserve(result, cap(result) + len(entries))
+	// Reserve space for new entries, minor waste as directories are also counted.
+	reserve(result, len(result) + len(entries))
 
-	working_dir, wd_err := os.get_working_directory(context.allocator)
-	if wd_err != nil {
-		fmt.eprintln("error: get working directory failed:", wd_err)
-		os.exit(1)
-	}
-	defer delete(working_dir)
-
-	for entry, i in entries {
-
-		if entry.type == os.File_Type.Directory {
-			append(queue, entry.fullpath)
-		}
-
-		if entry.type == os.File_Type.Regular {
-			relpath, rel_err := strings.replace(
-				entry.fullpath,
-				working_dir,
-				".",
-				1,
-				context.allocator,
-			)
-			append(
-				result,
-				DirectoryEntry{relpath = relpath, size = entry.size},
-			)
+	for entry in entries {
+		#partial switch entry.type {
+		case os.File_Type.Directory:
+			append(queue, strings.clone(entry.fullpath, queue^.allocator))
+		case os.File_Type.Regular:
+			{
+				relpath, was_allocation := strings.replace(
+					entry.fullpath,
+					working_dir,
+					".",
+					1,
+					result^.allocator,
+				)
+				if !was_allocation {
+					relpath = strings.clone(relpath, result^.allocator)
+				}
+				append(
+					result,
+					DirectoryEntry{relpath = relpath, size = entry.size},
+				)
+			}
+		case: // skip other types
 		}
 	}
 }