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ChildProcess.spawnWindows: Drastically reduce the amount of allocation during FileNotFound recovery

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Avoid a lot of unnecessary utf8 -> utf16 conversion and use a single ArrayList buffer for all the joined paths instead of a separate allocation for each join
This commit is contained in:
Ryan Liptak 2022-12-16 20:08:28 -08:00
parent 6a1021fb7d
commit b362cbbc9f
1 changed files with 22 additions and 33 deletions
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55
lib/std/child_process.zig
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@ -968,52 +968,41 @@ pub const ChildProcess = struct {
windowsCreateProcess(app_path_w.ptr, cmd_line_w.ptr, envp_ptr, cwd_w_ptr, &siStartInfo, &piProcInfo) catch |no_path_err| {
if (no_path_err != error.FileNotFound) return no_path_err;
var free_path = true;
const PATH = process.getEnvVarOwned(self.allocator, "PATH") catch |err| switch (err) {
error.EnvironmentVariableNotFound => blk: {
free_path = false;
break :blk "";
},
else => |e| return e,
};
defer if (free_path) self.allocator.free(PATH);
const PATH: [:0]const u16 = std.os.getenvW(unicode.utf8ToUtf16LeStringLiteral("PATH")) orelse &[_:0]u16{};
const PATHEXT: [:0]const u16 = std.os.getenvW(unicode.utf8ToUtf16LeStringLiteral("PATHEXT")) orelse &[_:0]u16{};
var free_path_ext = true;
const PATHEXT = process.getEnvVarOwned(self.allocator, "PATHEXT") catch |err| switch (err) {
error.EnvironmentVariableNotFound => blk: {
free_path_ext = false;
break :blk "";
},
else => |e| return e,
};
defer if (free_path_ext) self.allocator.free(PATHEXT);
var path_buf = std.ArrayListUnmanaged(u16){};
defer path_buf.deinit(self.allocator);
const app_name = self.argv[0];
const app_name_trimmed_w = try unicode.utf8ToUtf16LeWithNull(self.allocator, mem.trimLeft(u8, app_name, "\\/"));
defer self.allocator.free(app_name_trimmed_w);
var it = mem.tokenize(u8, PATH, ";");
var it = mem.tokenize(u16, PATH, &[_]u16{';'});
retry: while (it.next()) |search_path| {
const path_no_ext = try fs.path.join(self.allocator, &[_][]const u8{ search_path, app_name });
defer self.allocator.free(path_no_ext);
path_buf.clearRetainingCapacity();
const search_path_trimmed = mem.trimRight(u16, search_path, &[_]u16{ '\\', '/' });
try path_buf.appendSlice(self.allocator, search_path_trimmed);
try path_buf.append(self.allocator, fs.path.sep);
try path_buf.appendSlice(self.allocator, app_name_trimmed_w);
try path_buf.append(self.allocator, 0);
const path_no_ext = path_buf.items[0 .. path_buf.items.len - 1 :0];
const path_no_ext_w = try unicode.utf8ToUtf16LeWithNull(self.allocator, path_no_ext);
defer self.allocator.free(path_no_ext_w);
if (windowsCreateProcess(path_no_ext_w.ptr, cmd_line_w.ptr, envp_ptr, cwd_w_ptr, &siStartInfo, &piProcInfo)) |_| {
if (windowsCreateProcess(path_no_ext.ptr, cmd_line_w.ptr, envp_ptr, cwd_w_ptr, &siStartInfo, &piProcInfo)) |_| {
break :retry;
} else |err| switch (err) {
error.FileNotFound, error.AccessDenied => {},
else => return err,
}
var ext_it = mem.tokenize(u8, PATHEXT, ";");
while (ext_it.next()) |app_ext| {
const ext_w = try unicode.utf8ToUtf16LeWithNull(self.allocator, app_ext);
defer self.allocator.free(ext_w);
var ext_it = mem.tokenize(u16, PATHEXT, &[_]u16{';'});
while (ext_it.next()) |ext| {
path_buf.shrinkRetainingCapacity(path_no_ext.len);
try path_buf.appendSlice(self.allocator, ext);
try path_buf.append(self.allocator, 0);
const joined_path = path_buf.items[0 .. path_buf.items.len - 1 :0];
const joined_path_w = try std.mem.concatWithSentinel(self.allocator, u16, &.{ path_no_ext_w, ext_w }, 0);
defer self.allocator.free(joined_path_w);
if (windowsCreateProcess(joined_path_w.ptr, cmd_line_w.ptr, envp_ptr, cwd_w_ptr, &siStartInfo, &piProcInfo)) |_| {
if (windowsCreateProcess(joined_path.ptr, cmd_line_w.ptr, envp_ptr, cwd_w_ptr, &siStartInfo, &piProcInfo)) |_| {
break :retry;
} else |err| switch (err) {
error.FileNotFound => continue,