zig/lib/std /
Build/Watch.zig
The number to show as the number of directories being watched.
const builtin = @import("builtin");
const std = @import("../std.zig");
const Step = std.Build.Step;
const Allocator = std.mem.Allocator;
const assert = std.debug.assert;
const fatal = std.process.fatal;
const Watch = @This();
const FsEvents = @import("Watch/FsEvents.zig");
have_impl
Key is the directory to watch which contains one or more files we are interested in noticing changes to. Value is generation.
os: Os, /// The number to show as the number of directories being watched. dir_count: usize, // These fields are common to most implementations so are kept here for simplicity. // They are `undefined` on implementations which do not utilize then. dir_table: DirTable, generation: Generation,
hash()
Special key of "." means any changes in this directory trigger the steps.
pub const have_impl = Os != void;
eql()
Keyed differently but indexes correspond 1:1 with dir_table.
/// Key is the directory to watch which contains one or more files we are /// interested in noticing changes to. /// /// Value is generation. const DirTable = std.ArrayHashMapUnmanaged(Cache.Path, void, Cache.Path.TableAdapter, false);
init()
fanotify file descriptors are keyed by mount id since marks are limited to a single filesystem.
/// Special key of "." means any changes in this directory trigger the steps. const ReactionSet = std.StringArrayHashMapUnmanaged(StepSet); const StepSet = std.AutoArrayHashMapUnmanaged(*Step, Generation);
Match
Keyed differently but indexes correspond 1:1 with dir_table.
const Generation = u8;
Context
Start listening for events, buffer field will be overwritten eventually.
const Hash = std.hash.Wyhash; const Cache = std.Build.Cache;
hash()
Indexes correspond 1:1 with dir_table.
const Os = switch (builtin.os.tag) {
.linux => struct {
const posix = std.posix;
eql()
If the corresponding dir_table Path has sub_path == "", then it suffices as the open directory handle, and this value will be -1. Otherwise, it needs to be opened in update(), and will be stored here.
/// Keyed differently but indexes correspond 1:1 with `dir_table`.
handle_table: HandleTable,
/// fanotify file descriptors are keyed by mount id since marks
/// are limited to a single filesystem.
poll_fds: std.AutoArrayHashMapUnmanaged(MountId, posix.pollfd),
update()
Relative to the watched directory, the file path that triggers this match.
const MountId = i32;
const HandleTable = std.ArrayHashMapUnmanaged(FileHandle, struct { mount_id: MountId, reaction_set: ReactionSet }, FileHandle.Adapter, false);
Timeout
The step to re-run when file corresponding to basename is changed.
const fan_mask: std.os.linux.fanotify.MarkMask = .{
.CLOSE_WRITE = true,
.CREATE = true,
.DELETE = true,
.DELETE_SELF = true,
.EVENT_ON_CHILD = true,
.MOVED_FROM = true,
.MOVED_TO = true,
.MOVE_SELF = true,
.ONDIR = true,
};
to_i32_ms()
File system watching triggered on files that were marked as inputs to at least one Step. Relevant steps have been marked dirty.
const FileHandle = struct {
handle: *align(1) std.os.linux.file_handle,
toTimespec()
File system watching triggered but none of the events were relevant to what we are listening to. There is nothing to do.
fn clone(lfh: FileHandle, gpa: Allocator) Allocator.Error!FileHandle {
const bytes = lfh.slice();
const new_ptr = try gpa.alignedAlloc(
u8,
.of(std.os.linux.file_handle),
@sizeOf(std.os.linux.file_handle) + bytes.len,
);
const new_header: *std.os.linux.file_handle = @ptrCast(new_ptr);
new_header.* = lfh.handle.*;
const new: FileHandle = .{ .handle = new_header };
@memcpy(new.slice(), lfh.slice());
return new;
}
WaitResult
fn destroy(lfh: FileHandle, gpa: Allocator) void {
const ptr: [*]u8 = @ptrCast(lfh.handle);
const allocated_slice = ptr[0 .. @sizeOf(std.os.linux.file_handle) + lfh.handle.handle_bytes];
return gpa.free(allocated_slice);
}
wait()
fn slice(lfh: FileHandle) []u8 {
const ptr: [*]u8 = &lfh.handle.f_handle;
return ptr[0..lfh.handle.handle_bytes];
}
const Adapter = struct {
pub fn hash(self: Adapter, a: FileHandle) u32 {
_ = self;
const unsigned_type: u32 = @bitCast(a.handle.handle_type);
return @truncate(Hash.hash(unsigned_type, a.slice()));
}
pub fn eql(self: Adapter, a: FileHandle, b: FileHandle, b_index: usize) bool {
_ = self;
_ = b_index;
return a.handle.handle_type == b.handle.handle_type and std.mem.eql(u8, a.slice(), b.slice());
}
};
};
fn init() !Watch {
return .{
.dir_table = .{},
.dir_count = 0,
.os = switch (builtin.os.tag) {
.linux => .{
.handle_table = .{},
.poll_fds = .{},
},
else => {},
},
.generation = 0,
};
}
fn getDirHandle(gpa: Allocator, path: std.Build.Cache.Path, mount_id: *MountId) !FileHandle {
var file_handle_buffer: [@sizeOf(std.os.linux.file_handle) + 128]u8 align(@alignOf(std.os.linux.file_handle)) = undefined;
var buf: [std.fs.max_path_bytes]u8 = undefined;
const adjusted_path = if (path.sub_path.len == 0) "./" else std.fmt.bufPrint(&buf, "{s}/", .{
path.sub_path,
}) catch return error.NameTooLong;
const stack_ptr: *std.os.linux.file_handle = @ptrCast(&file_handle_buffer);
stack_ptr.handle_bytes = file_handle_buffer.len - @sizeOf(std.os.linux.file_handle);
try posix.name_to_handle_at(path.root_dir.handle.fd, adjusted_path, stack_ptr, mount_id, std.os.linux.AT.HANDLE_FID);
const stack_lfh: FileHandle = .{ .handle = stack_ptr };
return stack_lfh.clone(gpa);
}
fn markDirtySteps(w: *Watch, gpa: Allocator, fan_fd: posix.fd_t) !bool {
const fanotify = std.os.linux.fanotify;
const M = fanotify.event_metadata;
var events_buf: [256 + 4096]u8 = undefined;
var any_dirty = false;
while (true) {
var len = posix.read(fan_fd, &events_buf) catch |err| switch (err) {
error.WouldBlock => return any_dirty,
else => |e| return e,
};
var meta: [*]align(1) M = @ptrCast(&events_buf);
while (len >= @sizeOf(M) and meta[0].event_len >= @sizeOf(M) and meta[0].event_len <= len) : ({
len -= meta[0].event_len;
meta = @ptrCast(@as([*]u8, @ptrCast(meta)) + meta[0].event_len);
}) {
assert(meta[0].vers == M.VERSION);
if (meta[0].mask.Q_OVERFLOW) {
any_dirty = true;
std.log.warn("file system watch queue overflowed; falling back to fstat", .{});
markAllFilesDirty(w, gpa);
return true;
}
const fid: *align(1) fanotify.event_info_fid = @ptrCast(meta + 1);
switch (fid.hdr.info_type) {
.DFID_NAME => {
const file_handle: *align(1) std.os.linux.file_handle = @ptrCast(&fid.handle);
const file_name_z: [*:0]u8 = @ptrCast((&file_handle.f_handle).ptr + file_handle.handle_bytes);
const file_name = std.mem.span(file_name_z);
const lfh: FileHandle = .{ .handle = file_handle };
if (w.os.handle_table.getPtr(lfh)) |value| {
if (value.reaction_set.getPtr(".")) |glob_set|
any_dirty = markStepSetDirty(gpa, glob_set, any_dirty);
if (value.reaction_set.getPtr(file_name)) |step_set|
any_dirty = markStepSetDirty(gpa, step_set, any_dirty);
}
},
else => |t| std.log.warn("unexpected fanotify event '{s}'", .{@tagName(t)}),
}
}
}
}
fn update(w: *Watch, gpa: Allocator, steps: []const *Step) !void {
// Add missing marks and note persisted ones.
for (steps) |step| {
for (step.inputs.table.keys(), step.inputs.table.values()) |path, *files| {
const reaction_set = rs: {
const gop = try w.dir_table.getOrPut(gpa, path);
if (!gop.found_existing) {
var mount_id: MountId = undefined;
const dir_handle = Os.getDirHandle(gpa, path, &mount_id) catch |err| switch (err) {
error.FileNotFound => {
std.debug.assert(w.dir_table.swapRemove(path));
continue;
},
else => return err,
};
const fan_fd = blk: {
const fd_gop = try w.os.poll_fds.getOrPut(gpa, mount_id);
if (!fd_gop.found_existing) {
const fan_fd = std.posix.fanotify_init(.{
.CLASS = .NOTIF,
.CLOEXEC = true,
.NONBLOCK = true,
.REPORT_NAME = true,
.REPORT_DIR_FID = true,
.REPORT_FID = true,
.REPORT_TARGET_FID = true,
}, 0) catch |err| switch (err) {
error.UnsupportedFlags => fatal("fanotify_init failed due to old kernel; requires 5.17+", .{}),
else => |e| return e,
};
fd_gop.value_ptr.* = .{
.fd = fan_fd,
.events = std.posix.POLL.IN,
.revents = undefined,
};
}
break :blk fd_gop.value_ptr.*.fd;
};
// `dir_handle` may already be present in the table in
// the case that we have multiple Cache.Path instances
// that compare inequal but ultimately point to the same
// directory on the file system.
// In such case, we must revert adding this directory, but keep
// the additions to the step set.
const dh_gop = try w.os.handle_table.getOrPut(gpa, dir_handle);
if (dh_gop.found_existing) {
_ = w.dir_table.pop();
} else {
assert(dh_gop.index == gop.index);
dh_gop.value_ptr.* = .{ .mount_id = mount_id, .reaction_set = .{} };
posix.fanotify_mark(fan_fd, .{
.ADD = true,
.ONLYDIR = true,
}, fan_mask, path.root_dir.handle.fd, path.subPathOrDot()) catch |err| {
fatal("unable to watch {f}: {s}", .{ path, @errorName(err) });
};
}
break :rs &dh_gop.value_ptr.reaction_set;
}
break :rs &w.os.handle_table.values()[gop.index].reaction_set;
};
for (files.items) |basename| {
const gop = try reaction_set.getOrPut(gpa, basename);
if (!gop.found_existing) gop.value_ptr.* = .{};
try gop.value_ptr.put(gpa, step, w.generation);
}
}
}
{
// Remove marks for files that are no longer inputs.
var i: usize = 0;
while (i < w.os.handle_table.entries.len) {
{
const reaction_set = &w.os.handle_table.values()[i].reaction_set;
var step_set_i: usize = 0;
while (step_set_i < reaction_set.entries.len) {
const step_set = &reaction_set.values()[step_set_i];
var dirent_i: usize = 0;
while (dirent_i < step_set.entries.len) {
const generations = step_set.values();
if (generations[dirent_i] == w.generation) {
dirent_i += 1;
continue;
}
step_set.swapRemoveAt(dirent_i);
}
if (step_set.entries.len > 0) {
step_set_i += 1;
continue;
}
reaction_set.swapRemoveAt(step_set_i);
}
if (reaction_set.entries.len > 0) {
i += 1;
continue;
}
}
const path = w.dir_table.keys()[i];
const mount_id = w.os.handle_table.values()[i].mount_id;
const fan_fd = w.os.poll_fds.getEntry(mount_id).?.value_ptr.fd;
posix.fanotify_mark(fan_fd, .{
.REMOVE = true,
.ONLYDIR = true,
}, fan_mask, path.root_dir.handle.fd, path.subPathOrDot()) catch |err| switch (err) {
error.FileNotFound => {}, // Expected, harmless.
else => |e| std.log.warn("unable to unwatch '{f}': {s}", .{ path, @errorName(e) }),
};
w.dir_table.swapRemoveAt(i);
w.os.handle_table.swapRemoveAt(i);
}
w.generation +%= 1;
}
w.dir_count = w.dir_table.count();
}
fn wait(w: *Watch, gpa: Allocator, timeout: Timeout) !WaitResult {
const events_len = try std.posix.poll(w.os.poll_fds.values(), timeout.to_i32_ms());
if (events_len == 0)
return .timeout;
for (w.os.poll_fds.values()) |poll_fd| {
if (poll_fd.revents & std.posix.POLL.IN == std.posix.POLL.IN and try Os.markDirtySteps(w, gpa, poll_fd.fd))
return .dirty;
}
return .clean;
}
},
.windows => struct {
const windows = std.os.windows;
/// Keyed differently but indexes correspond 1:1 with `dir_table`.
handle_table: HandleTable,
dir_list: std.AutoArrayHashMapUnmanaged(usize, *Directory),
io_cp: ?windows.HANDLE,
counter: usize = 0,
const HandleTable = std.AutoArrayHashMapUnmanaged(FileId, ReactionSet);
const FileId = struct {
volumeSerialNumber: windows.ULONG,
indexNumber: windows.LARGE_INTEGER,
};
const Directory = struct {
handle: windows.HANDLE,
id: FileId,
overlapped: windows.OVERLAPPED,
// 64 KB is the packet size limit when monitoring over a network.
// https://learn.microsoft.com/en-us/windows/win32/api/winbase/nf-winbase-readdirectorychangesw#remarks
buffer: [64 * 1024]u8 align(@alignOf(windows.FILE_NOTIFY_INFORMATION)) = undefined,
/// Start listening for events, buffer field will be overwritten eventually.
fn startListening(self: *@This()) !void {
const r = windows.kernel32.ReadDirectoryChangesW(
self.handle,
@ptrCast(&self.buffer),
self.buffer.len,
0,
.{
.creation = true,
.dir_name = true,
.file_name = true,
.last_write = true,
.size = true,
},
null,
&self.overlapped,
null,
);
if (r == windows.FALSE) {
switch (windows.GetLastError()) {
.INVALID_FUNCTION => return error.ReadDirectoryChangesUnsupported,
else => |err| return windows.unexpectedError(err),
}
}
}
fn init(gpa: Allocator, path: Cache.Path) !*@This() {
// The following code is a drawn out NtCreateFile call. (mostly adapted from std.fs.Dir.makeOpenDirAccessMaskW)
// It's necessary in order to get the specific flags that are required when calling ReadDirectoryChangesW.
var dir_handle: windows.HANDLE = undefined;
const root_fd = path.root_dir.handle.fd;
const sub_path = path.subPathOrDot();
const sub_path_w = try windows.sliceToPrefixedFileW(root_fd, sub_path);
const path_len_bytes = std.math.cast(u16, sub_path_w.len * 2) orelse return error.NameTooLong;
var nt_name = windows.UNICODE_STRING{
.Length = @intCast(path_len_bytes),
.MaximumLength = @intCast(path_len_bytes),
.Buffer = @constCast(sub_path_w.span().ptr),
};
var attr = windows.OBJECT_ATTRIBUTES{
.Length = @sizeOf(windows.OBJECT_ATTRIBUTES),
.RootDirectory = if (std.fs.path.isAbsoluteWindowsW(sub_path_w.span())) null else root_fd,
.Attributes = 0, // Note we do not use OBJ_CASE_INSENSITIVE here.
.ObjectName = &nt_name,
.SecurityDescriptor = null,
.SecurityQualityOfService = null,
};
var io: windows.IO_STATUS_BLOCK = undefined;
switch (windows.ntdll.NtCreateFile(
&dir_handle,
windows.SYNCHRONIZE | windows.GENERIC_READ | windows.FILE_LIST_DIRECTORY,
&attr,
&io,
null,
0,
windows.FILE_SHARE_READ | windows.FILE_SHARE_WRITE | windows.FILE_SHARE_DELETE,
windows.FILE_OPEN,
windows.FILE_DIRECTORY_FILE | windows.FILE_OPEN_FOR_BACKUP_INTENT,
null,
0,
)) {
.SUCCESS => {},
.OBJECT_NAME_INVALID => return error.BadPathName,
.OBJECT_NAME_NOT_FOUND => return error.FileNotFound,
.OBJECT_NAME_COLLISION => return error.PathAlreadyExists,
.OBJECT_PATH_NOT_FOUND => return error.FileNotFound,
.NOT_A_DIRECTORY => return error.NotDir,
// This can happen if the directory has 'List folder contents' permission set to 'Deny'
.ACCESS_DENIED => return error.AccessDenied,
.INVALID_PARAMETER => unreachable,
else => |rc| return windows.unexpectedStatus(rc),
}
assert(dir_handle != windows.INVALID_HANDLE_VALUE);
errdefer windows.CloseHandle(dir_handle);
const dir_id = try getFileId(dir_handle);
const dir_ptr = try gpa.create(@This());
dir_ptr.* = .{
.handle = dir_handle,
.id = dir_id,
.overlapped = std.mem.zeroes(windows.OVERLAPPED),
};
return dir_ptr;
}
fn deinit(self: *@This(), gpa: Allocator) void {
_ = windows.kernel32.CancelIo(self.handle);
windows.CloseHandle(self.handle);
gpa.destroy(self);
}
};
fn init() !Watch {
return .{
.dir_table = .{},
.dir_count = 0,
.os = switch (builtin.os.tag) {
.windows => .{
.handle_table = .{},
.dir_list = .{},
.io_cp = null,
},
else => {},
},
.generation = 0,
};
}
fn getFileId(handle: windows.HANDLE) !FileId {
var file_id: FileId = undefined;
var io_status: windows.IO_STATUS_BLOCK = undefined;
var volume_info: windows.FILE_FS_VOLUME_INFORMATION = undefined;
switch (windows.ntdll.NtQueryVolumeInformationFile(
handle,
&io_status,
&volume_info,
@sizeOf(windows.FILE_FS_VOLUME_INFORMATION),
.FileFsVolumeInformation,
)) {
.SUCCESS => {},
// Buffer overflow here indicates that there is more information available than was able to be stored in the buffer
// size provided. This is treated as success because the type of variable-length information that this would be relevant for
// (name, volume name, etc) we don't care about.
.BUFFER_OVERFLOW => {},
else => |rc| return windows.unexpectedStatus(rc),
}
file_id.volumeSerialNumber = volume_info.VolumeSerialNumber;
var internal_info: windows.FILE_INTERNAL_INFORMATION = undefined;
switch (windows.ntdll.NtQueryInformationFile(
handle,
&io_status,
&internal_info,
@sizeOf(windows.FILE_INTERNAL_INFORMATION),
.FileInternalInformation,
)) {
.SUCCESS => {},
else => |rc| return windows.unexpectedStatus(rc),
}
file_id.indexNumber = internal_info.IndexNumber;
return file_id;
}
fn markDirtySteps(w: *Watch, gpa: Allocator, dir: *Directory) !bool {
var any_dirty = false;
const bytes_returned = try windows.GetOverlappedResult(dir.handle, &dir.overlapped, false);
if (bytes_returned == 0) {
std.log.warn("file system watch queue overflowed; falling back to fstat", .{});
markAllFilesDirty(w, gpa);
try dir.startListening();
return true;
}
var file_name_buf: [std.fs.max_path_bytes]u8 = undefined;
var notify: *align(1) windows.FILE_NOTIFY_INFORMATION = undefined;
var offset: usize = 0;
while (true) {
notify = @ptrCast(&dir.buffer[offset]);
const file_name_field: [*]u16 = @ptrFromInt(@intFromPtr(notify) + @sizeOf(windows.FILE_NOTIFY_INFORMATION));
const file_name_len = std.unicode.wtf16LeToWtf8(&file_name_buf, file_name_field[0 .. notify.FileNameLength / 2]);
const file_name = file_name_buf[0..file_name_len];
if (w.os.handle_table.getIndex(dir.id)) |reaction_set_i| {
const reaction_set = w.os.handle_table.values()[reaction_set_i];
if (reaction_set.getPtr(".")) |glob_set|
any_dirty = markStepSetDirty(gpa, glob_set, any_dirty);
if (reaction_set.getPtr(file_name)) |step_set| {
any_dirty = markStepSetDirty(gpa, step_set, any_dirty);
}
}
if (notify.NextEntryOffset == 0)
break;
offset += notify.NextEntryOffset;
}
// We call this now since at this point we have finished reading dir.buffer.
try dir.startListening();
return any_dirty;
}
fn update(w: *Watch, gpa: Allocator, steps: []const *Step) !void {
// Add missing marks and note persisted ones.
for (steps) |step| {
for (step.inputs.table.keys(), step.inputs.table.values()) |path, *files| {
const reaction_set = rs: {
const gop = try w.dir_table.getOrPut(gpa, path);
if (!gop.found_existing) {
const dir = try Os.Directory.init(gpa, path);
errdefer dir.deinit(gpa);
// `dir.id` may already be present in the table in
// the case that we have multiple Cache.Path instances
// that compare inequal but ultimately point to the same
// directory on the file system.
// In such case, we must revert adding this directory, but keep
// the additions to the step set.
const dh_gop = try w.os.handle_table.getOrPut(gpa, dir.id);
if (dh_gop.found_existing) {
dir.deinit(gpa);
_ = w.dir_table.pop();
} else {
assert(dh_gop.index == gop.index);
dh_gop.value_ptr.* = .{};
try dir.startListening();
const key = w.os.counter;
w.os.counter +%= 1;
try w.os.dir_list.put(gpa, key, dir);
w.os.io_cp = try windows.CreateIoCompletionPort(
dir.handle,
w.os.io_cp,
key,
0,
);
}
break :rs &w.os.handle_table.values()[dh_gop.index];
}
break :rs &w.os.handle_table.values()[gop.index];
};
for (files.items) |basename| {
const gop = try reaction_set.getOrPut(gpa, basename);
if (!gop.found_existing) gop.value_ptr.* = .{};
try gop.value_ptr.put(gpa, step, w.generation);
}
}
}
{
// Remove marks for files that are no longer inputs.
var i: usize = 0;
while (i < w.os.handle_table.entries.len) {
{
const reaction_set = &w.os.handle_table.values()[i];
var step_set_i: usize = 0;
while (step_set_i < reaction_set.entries.len) {
const step_set = &reaction_set.values()[step_set_i];
var dirent_i: usize = 0;
while (dirent_i < step_set.entries.len) {
const generations = step_set.values();
if (generations[dirent_i] == w.generation) {
dirent_i += 1;
continue;
}
step_set.swapRemoveAt(dirent_i);
}
if (step_set.entries.len > 0) {
step_set_i += 1;
continue;
}
reaction_set.swapRemoveAt(step_set_i);
}
if (reaction_set.entries.len > 0) {
i += 1;
continue;
}
}
w.os.dir_list.values()[i].deinit(gpa);
w.os.dir_list.swapRemoveAt(i);
w.dir_table.swapRemoveAt(i);
w.os.handle_table.swapRemoveAt(i);
}
w.generation +%= 1;
}
w.dir_count = w.dir_table.count();
}
fn wait(w: *Watch, gpa: Allocator, timeout: Timeout) !WaitResult {
var bytes_transferred: std.os.windows.DWORD = undefined;
var key: usize = undefined;
var overlapped_ptr: ?*std.os.windows.OVERLAPPED = undefined;
return while (true) switch (std.os.windows.GetQueuedCompletionStatus(
w.os.io_cp.?,
&bytes_transferred,
&key,
&overlapped_ptr,
@bitCast(timeout.to_i32_ms()),
)) {
.Normal => {
if (bytes_transferred == 0)
break error.Unexpected;
// This 'orelse' detects a race condition that happens when we receive a
// completion notification for a directory that no longer exists in our list.
const dir = w.os.dir_list.get(key) orelse break .clean;
break if (try Os.markDirtySteps(w, gpa, dir))
.dirty
else
.clean;
},
.Timeout => break .timeout,
// This status is issued because CancelIo was called, skip and try again.
.Cancelled => continue,
else => break error.Unexpected,
};
}
},
.dragonfly, .freebsd, .netbsd, .openbsd, .ios, .tvos, .visionos, .watchos => struct {
const posix = std.posix;
kq_fd: i32,
/// Indexes correspond 1:1 with `dir_table`.
handles: std.MultiArrayList(struct {
rs: ReactionSet,
/// If the corresponding dir_table Path has sub_path == "", then it
/// suffices as the open directory handle, and this value will be
/// -1. Otherwise, it needs to be opened in update(), and will be
/// stored here.
dir_fd: i32,
}),
const dir_open_flags: posix.O = f: {
var f: posix.O = .{
.ACCMODE = .RDONLY,
.NOFOLLOW = false,
.DIRECTORY = true,
.CLOEXEC = true,
};
if (@hasField(posix.O, "EVTONLY")) f.EVTONLY = true;
if (@hasField(posix.O, "PATH")) f.PATH = true;
break :f f;
};
const EV = std.c.EV;
const NOTE = std.c.NOTE;
fn init() !Watch {
const kq_fd = try posix.kqueue();
errdefer posix.close(kq_fd);
return .{
.dir_table = .{},
.dir_count = 0,
.os = .{
.kq_fd = kq_fd,
.handles = .empty,
},
.generation = 0,
};
}
fn update(w: *Watch, gpa: Allocator, steps: []const *Step) !void {
const handles = &w.os.handles;
for (steps) |step| {
for (step.inputs.table.keys(), step.inputs.table.values()) |path, *files| {
const reaction_set = rs: {
const gop = try w.dir_table.getOrPut(gpa, path);
if (!gop.found_existing) {
const skip_open_dir = path.sub_path.len == 0;
const dir_fd = if (skip_open_dir)
path.root_dir.handle.fd
else
posix.openat(path.root_dir.handle.fd, path.sub_path, dir_open_flags, 0) catch |err| {
fatal("failed to open directory {f}: {s}", .{ path, @errorName(err) });
};
// Empirically the dir has to stay open or else no events are triggered.
errdefer if (!skip_open_dir) posix.close(dir_fd);
const changes = [1]posix.Kevent{.{
.ident = @bitCast(@as(isize, dir_fd)),
.filter = std.c.EVFILT.VNODE,
.flags = EV.ADD | EV.ENABLE | EV.CLEAR,
.fflags = NOTE.DELETE | NOTE.WRITE | NOTE.RENAME | NOTE.REVOKE,
.data = 0,
.udata = gop.index,
}};
_ = try posix.kevent(w.os.kq_fd, &changes, &.{}, null);
assert(handles.len == gop.index);
try handles.append(gpa, .{
.rs = .{},
.dir_fd = if (skip_open_dir) -1 else dir_fd,
});
}
break :rs &handles.items(.rs)[gop.index];
};
for (files.items) |basename| {
const gop = try reaction_set.getOrPut(gpa, basename);
if (!gop.found_existing) gop.value_ptr.* = .{};
try gop.value_ptr.put(gpa, step, w.generation);
}
}
}
{
// Remove marks for files that are no longer inputs.
var i: usize = 0;
while (i < handles.len) {
{
const reaction_set = &handles.items(.rs)[i];
var step_set_i: usize = 0;
while (step_set_i < reaction_set.entries.len) {
const step_set = &reaction_set.values()[step_set_i];
var dirent_i: usize = 0;
while (dirent_i < step_set.entries.len) {
const generations = step_set.values();
if (generations[dirent_i] == w.generation) {
dirent_i += 1;
continue;
}
step_set.swapRemoveAt(dirent_i);
}
if (step_set.entries.len > 0) {
step_set_i += 1;
continue;
}
reaction_set.swapRemoveAt(step_set_i);
}
if (reaction_set.entries.len > 0) {
i += 1;
continue;
}
}
// If the sub_path == "" then this patch has already the
// dir fd that we need to use as the ident to remove the
// event. If it was opened above with openat() then we need
// to access that data via the dir_fd field.
const path = w.dir_table.keys()[i];
const dir_fd = if (path.sub_path.len == 0)
path.root_dir.handle.fd
else
handles.items(.dir_fd)[i];
assert(dir_fd != -1);
// The changelist also needs to update the udata field of the last
// event, since we are doing a swap remove, and we store the dir_table
// index in the udata field.
const last_dir_fd = fd: {
const last_path = w.dir_table.keys()[handles.len - 1];
const last_dir_fd = if (last_path.sub_path.len == 0)
last_path.root_dir.handle.fd
else
handles.items(.dir_fd)[handles.len - 1];
assert(last_dir_fd != -1);
break :fd last_dir_fd;
};
const changes = [_]posix.Kevent{
.{
.ident = @bitCast(@as(isize, dir_fd)),
.filter = std.c.EVFILT.VNODE,
.flags = EV.DELETE,
.fflags = 0,
.data = 0,
.udata = i,
},
.{
.ident = @bitCast(@as(isize, last_dir_fd)),
.filter = std.c.EVFILT.VNODE,
.flags = EV.ADD,
.fflags = NOTE.DELETE | NOTE.WRITE | NOTE.RENAME | NOTE.REVOKE,
.data = 0,
.udata = i,
},
};
const filtered_changes = if (i == handles.len - 1) changes[0..1] else &changes;
_ = try posix.kevent(w.os.kq_fd, filtered_changes, &.{}, null);
if (path.sub_path.len != 0) posix.close(dir_fd);
w.dir_table.swapRemoveAt(i);
handles.swapRemove(i);
}
w.generation +%= 1;
}
w.dir_count = w.dir_table.count();
}
fn wait(w: *Watch, gpa: Allocator, timeout: Timeout) !WaitResult {
var timespec_buffer: posix.timespec = undefined;
var event_buffer: [100]posix.Kevent = undefined;
var n = try posix.kevent(w.os.kq_fd, &.{}, &event_buffer, timeout.toTimespec(×pec_buffer));
if (n == 0) return .timeout;
const reaction_sets = w.os.handles.items(.rs);
var any_dirty = markDirtySteps(gpa, reaction_sets, event_buffer[0..n], false);
timespec_buffer = .{ .sec = 0, .nsec = 0 };
while (n == event_buffer.len) {
n = try posix.kevent(w.os.kq_fd, &.{}, &event_buffer, ×pec_buffer);
if (n == 0) break;
any_dirty = markDirtySteps(gpa, reaction_sets, event_buffer[0..n], any_dirty);
}
return if (any_dirty) .dirty else .clean;
}
fn markDirtySteps(
gpa: Allocator,
reaction_sets: []ReactionSet,
events: []const std.c.Kevent,
start_any_dirty: bool,
) bool {
var any_dirty = start_any_dirty;
for (events) |event| {
const index: usize = @intCast(event.udata);
const reaction_set = &reaction_sets[index];
// If we knew the basename of the changed file, here we would
// mark only the step set dirty, and possibly the glob set:
//if (reaction_set.getPtr(".")) |glob_set|
// any_dirty = markStepSetDirty(gpa, glob_set, any_dirty);
//if (reaction_set.getPtr(file_name)) |step_set|
// any_dirty = markStepSetDirty(gpa, step_set, any_dirty);
// However we don't know the file name so just mark all the
// sets dirty for this directory.
for (reaction_set.values()) |*step_set| {
any_dirty = markStepSetDirty(gpa, step_set, any_dirty);
}
}
return any_dirty;
}
},
.macos => struct {
fse: FsEvents,
fn init() !Watch {
return .{
.os = .{ .fse = try .init() },
.dir_count = 0,
.dir_table = undefined,
.generation = undefined,
};
}
fn update(w: *Watch, gpa: Allocator, steps: []const *Step) !void {
try w.os.fse.setPaths(gpa, steps);
w.dir_count = w.os.fse.watch_roots.len;
}
fn wait(w: *Watch, gpa: Allocator, timeout: Timeout) !WaitResult {
return w.os.fse.wait(gpa, switch (timeout) {
.none => null,
.ms => |ms| @as(u64, ms) * std.time.ns_per_ms,
});
}
},
else => void,
};
pub fn init() !Watch {
return Os.init();
}
pub const Match = struct {
/// Relative to the watched directory, the file path that triggers this
/// match.
basename: []const u8,
/// The step to re-run when file corresponding to `basename` is changed.
step: *Step,
pub const Context = struct {
pub fn hash(self: Context, a: Match) u32 {
_ = self;
var hasher = Hash.init(0);
std.hash.autoHash(&hasher, a.step);
hasher.update(a.basename);
return @truncate(hasher.final());
}
pub fn eql(self: Context, a: Match, b: Match, b_index: usize) bool {
_ = self;
_ = b_index;
return a.step == b.step and std.mem.eql(u8, a.basename, b.basename);
}
};
};
fn markAllFilesDirty(w: *Watch, gpa: Allocator) void {
for (w.os.handle_table.values()) |value| {
const reaction_set = switch (builtin.os.tag) {
.linux => value.reaction_set,
else => value,
};
for (reaction_set.values()) |step_set| {
for (step_set.keys()) |step| {
step.recursiveReset(gpa);
}
}
}
}
fn markStepSetDirty(gpa: Allocator, step_set: *StepSet, any_dirty: bool) bool {
var this_any_dirty = false;
for (step_set.keys()) |step| {
if (step.state != .precheck_done) {
step.recursiveReset(gpa);
this_any_dirty = true;
}
}
return any_dirty or this_any_dirty;
}
pub fn update(w: *Watch, gpa: Allocator, steps: []const *Step) !void {
return Os.update(w, gpa, steps);
}
pub const Timeout = union(enum) {
none,
ms: u16,
pub fn to_i32_ms(t: Timeout) i32 {
return switch (t) {
.none => -1,
.ms => |ms| ms,
};
}
pub fn toTimespec(t: Timeout, buf: *std.posix.timespec) ?*std.posix.timespec {
return switch (t) {
.none => null,
.ms => |ms_u16| {
const ms: isize = ms_u16;
buf.* = .{
.sec = @divTrunc(ms, std.time.ms_per_s),
.nsec = @rem(ms, std.time.ms_per_s) * std.time.ns_per_ms,
};
return buf;
},
};
}
};
pub const WaitResult = enum {
timeout,
/// File system watching triggered on files that were marked as inputs to at least one Step.
/// Relevant steps have been marked dirty.
dirty,
/// File system watching triggered but none of the events were relevant to
/// what we are listening to. There is nothing to do.
clean,
};
pub fn wait(w: *Watch, gpa: Allocator, timeout: Timeout) !WaitResult {
return Os.wait(w, gpa, timeout);
}