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proof-of-concept --watch implementation based on fanotify

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So far, only implemented for InstallFile steps.

Default debounce interval bumped to 50ms. I think it should be
configurable.

Next I have an idea to simplify the fanotify implementation, but other
OS implementations might want to refer back to this commit before I make
those changes.
This commit is contained in:
Andrew Kelley 2024-07-09 18:17:27 -07:00
parent c5a4177140
commit 5ee3971b18
3 changed files with 208 additions and 148 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

208
lib/compiler/build_runner.zig
View File

@ -8,6 +8,7 @@ const process = std.process;
const ArrayList = std.ArrayList;
const File = std.fs.File;
const Step = std.Build.Step;
const Watch = std.Build.Watch;
const Allocator = std.mem.Allocator;
pub const root = @import("@build");
@ -400,34 +401,26 @@ pub fn main() !void {
};
if (!watch) return cleanExit();
// Clear all file handles.
for (w.handle_table.keys(), w.handle_table.values()) |lfh, *step_set| {
lfh.destroy(gpa);
step_set.clearAndFree(gpa);
}
w.handle_table.clearRetainingCapacity();
// Add missing marks and note persisted ones.
for (run.step_stack.keys()) |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);
gop.value_ptr.* = w.generation;
if (!gop.found_existing) {
try std.posix.fanotify_mark(w.fan_fd, .{
.ADD = true,
.ONLYDIR = true,
}, Watch.fan_mask, path.root_dir.handle.fd, path.subPathOpt());
const dir_handle = try Watch.getDirHandle(gpa, path);
try w.handle_table.putNoClobber(gpa, dir_handle, .{});
}
}
break :rs &w.handle_table.values()[gop.index];
};
for (files.items) |basename| {
const file_handle = try Watch.getFileHandle(gpa, path, basename);
std.debug.print("watching file_handle '{}{s}' = {}\n", .{
path, basename, std.fmt.fmtSliceHexLower(file_handle.slice()),
});
const gop = try w.handle_table.getOrPut(gpa, file_handle);
const gop = try reaction_set.getOrPut(gpa, basename);
if (!gop.found_existing) gop.value_ptr.* = .{};
try gop.value_ptr.put(gpa, step, {});
try gop.value_ptr.put(gpa, step, w.generation);
}
}
}
@ -435,12 +428,32 @@ pub fn main() !void {
{
// Remove marks for files that are no longer inputs.
var i: usize = 0;
while (i < w.dir_table.entries.len) {
const generations = w.dir_table.values();
if (generations[i] == w.generation) {
while (i < w.handle_table.entries.len) {
{
const reaction_set = &w.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;
}
}
const path = w.dir_table.keys()[i];
@ -450,6 +463,7 @@ pub fn main() !void {
}, Watch.fan_mask, path.root_dir.handle.fd, path.subPathOpt());
w.dir_table.swapRemoveAt(i);
w.handle_table.swapRemoveAt(i);
}
w.generation +%= 1;
}
@ -459,7 +473,7 @@ pub fn main() !void {
// if any more events come in. After the debounce interval has passed,
// trigger a rebuild on all steps with modified inputs, as well as their
// recursive dependants.
const debounce_interval_ms = 10;
const debounce_interval_ms = 50;
var poll_fds: [1]std.posix.pollfd = .{
.{
.fd = w.fan_fd,
@ -517,46 +531,48 @@ fn markDirtySteps(w: *Watch) !bool {
const file_name = mem.span(file_name_z);
std.debug.print("DFID_NAME file_handle = {any}, found: '{s}'\n", .{ file_handle.*, file_name });
const lfh: Watch.LinuxFileHandle = .{ .handle = file_handle };
if (w.handle_table.get(lfh)) |step_set| {
if (w.handle_table.getPtr(lfh)) |reaction_set| {
if (reaction_set.getPtr(file_name)) |step_set| {
for (step_set.keys()) |step| {
std.debug.print("DFID_NAME marking step '{s}' dirty\n", .{step.name});
step.state = .precheck_done;
any_dirty = true;
}
}
} else {
std.debug.print("DFID_NAME changed file did not match any steps: '{}'\n", .{
std.debug.print("DFID_NAME changed file did not match any directories: '{}'\n", .{
std.fmt.fmtSliceHexLower(lfh.slice()),
});
}
},
.FID => {
const file_handle: *align(1) std.os.linux.file_handle = @ptrCast(&fid.handle);
const lfh: Watch.LinuxFileHandle = .{ .handle = file_handle };
if (w.handle_table.get(lfh)) |step_set| {
for (step_set.keys()) |step| {
std.debug.print("FID marking step '{s}' dirty\n", .{step.name});
step.state = .precheck_done;
any_dirty = true;
}
} else {
std.debug.print("FID changed file did not match any steps: '{}'\n", .{
std.fmt.fmtSliceHexLower(lfh.slice()),
});
}
},
.DFID => {
const file_handle: *align(1) std.os.linux.file_handle = @ptrCast(&fid.handle);
const lfh: Watch.LinuxFileHandle = .{ .handle = file_handle };
if (w.handle_table.get(lfh)) |step_set| {
for (step_set.keys()) |step| {
std.debug.print("DFID marking step '{s}' dirty\n", .{step.name});
step.state = .precheck_done;
any_dirty = true;
}
} else {
std.debug.print("DFID changed file did not match any steps\n", .{});
}
},
//.FID => {
// const file_handle: *align(1) std.os.linux.file_handle = @ptrCast(&fid.handle);
// const lfh: Watch.LinuxFileHandle = .{ .handle = file_handle };
// if (w.handle_table.get(lfh)) |step_set| {
// for (step_set.keys()) |step| {
// std.debug.print("FID marking step '{s}' dirty\n", .{step.name});
// step.state = .precheck_done;
// any_dirty = true;
// }
// } else {
// std.debug.print("FID changed file did not match any steps: '{}'\n", .{
// std.fmt.fmtSliceHexLower(lfh.slice()),
// });
// }
//},
//.DFID => {
// const file_handle: *align(1) std.os.linux.file_handle = @ptrCast(&fid.handle);
// const lfh: Watch.LinuxFileHandle = .{ .handle = file_handle };
// if (w.handle_table.get(lfh)) |step_set| {
// for (step_set.keys()) |step| {
// std.debug.print("DFID marking step '{s}' dirty\n", .{step.name});
// step.state = .precheck_done;
// any_dirty = true;
// }
// } else {
// std.debug.print("DFID changed file did not match any steps\n", .{});
// }
//},
else => |t| {
std.debug.panic("TODO: received event type '{s}'", .{@tagName(t)});
},
@ -565,98 +581,6 @@ fn markDirtySteps(w: *Watch) !bool {
}
}
const Watch = struct {
dir_table: DirTable,
handle_table: HandleTable,
fan_fd: std.posix.fd_t,
generation: u8,
const fan_mask: std.os.linux.fanotify.MarkMask = .{
.CLOSE_WRITE = true,
.DELETE = true,
.MOVED_FROM = true,
.MOVED_TO = true,
.EVENT_ON_CHILD = true,
};
const init: Watch = .{
.dir_table = .{},
.handle_table = .{},
.fan_fd = -1,
.generation = 0,
};
/// 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, u8, Cache.Path.TableAdapter, false);
const HandleTable = std.ArrayHashMapUnmanaged(LinuxFileHandle, StepSet, LinuxFileHandle.Adapter, false);
const StepSet = std.AutoArrayHashMapUnmanaged(*Step, void);
const Hash = std.hash.Wyhash;
const Cache = std.Build.Cache;
const LinuxFileHandle = struct {
handle: *align(1) std.os.linux.file_handle,
fn clone(lfh: LinuxFileHandle, gpa: Allocator) Allocator.Error!LinuxFileHandle {
const bytes = lfh.slice();
const new_ptr = try gpa.alignedAlloc(
u8,
@alignOf(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: LinuxFileHandle = .{ .handle = new_header };
@memcpy(new.slice(), lfh.slice());
return new;
}
fn destroy(lfh: LinuxFileHandle, 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);
}
fn slice(lfh: LinuxFileHandle) []u8 {
const ptr: [*]u8 = &lfh.handle.f_handle;
return ptr[0..lfh.handle.handle_bytes];
}
const Adapter = struct {
pub fn hash(self: Adapter, a: LinuxFileHandle) 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: LinuxFileHandle, b: LinuxFileHandle, b_index: usize) bool {
_ = self;
_ = b_index;
return a.handle.handle_type == b.handle.handle_type and mem.eql(u8, a.slice(), b.slice());
}
};
};
fn getFileHandle(gpa: Allocator, path: std.Build.Cache.Path, basename: []const u8) !LinuxFileHandle {
var file_handle_buffer: [@sizeOf(std.os.linux.file_handle) + 128]u8 align(@alignOf(std.os.linux.file_handle)) = undefined;
var mount_id: i32 = undefined;
var buf: [std.fs.max_path_bytes]u8 = undefined;
const joined_path = if (path.sub_path.len == 0) basename else path: {
break :path std.fmt.bufPrint(&buf, "{s}" ++ std.fs.path.sep_str ++ "{s}", .{
path.sub_path, basename,
}) 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 std.posix.name_to_handle_at(path.root_dir.handle.fd, joined_path, stack_ptr, &mount_id, 0);
const stack_lfh: LinuxFileHandle = .{ .handle = stack_ptr };
return stack_lfh.clone(gpa);
}
};
const Run = struct {
max_rss: u64,
max_rss_is_default: bool,

1
lib/std/Build.zig
View File

@ -20,6 +20,7 @@ const Build = @This();
pub const Cache = @import("Build/Cache.zig");
pub const Step = @import("Build/Step.zig");
pub const Module = @import("Build/Module.zig");
pub const Watch = @import("Build/Watch.zig");
/// Shared state among all Build instances.
graph: *Graph,

135
lib/std/Build/Watch.zig Normal file
View File

@ -0,0 +1,135 @@
const std = @import("../std.zig");
const Watch = @This();
const Step = std.Build.Step;
const Allocator = std.mem.Allocator;
dir_table: DirTable,
/// Keyed differently but indexes correspond 1:1 with `dir_table`.
handle_table: HandleTable,
fan_fd: std.posix.fd_t,
generation: Generation,
pub const fan_mask: std.os.linux.fanotify.MarkMask = .{
.CLOSE_WRITE = true,
.DELETE = true,
.MOVED_FROM = true,
.MOVED_TO = true,
.EVENT_ON_CHILD = true,
};
pub const init: Watch = .{
.dir_table = .{},
.handle_table = .{},
.fan_fd = -1,
.generation = 0,
};
/// 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);
const HandleTable = std.ArrayHashMapUnmanaged(LinuxFileHandle, ReactionSet, LinuxFileHandle.Adapter, false);
const ReactionSet = std.StringArrayHashMapUnmanaged(StepSet);
const StepSet = std.AutoArrayHashMapUnmanaged(*Step, Generation);
const Generation = u8;
const Hash = std.hash.Wyhash;
const Cache = std.Build.Cache;
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);
}
};
};
pub const LinuxFileHandle = struct {
handle: *align(1) std.os.linux.file_handle,
pub fn clone(lfh: LinuxFileHandle, gpa: Allocator) Allocator.Error!LinuxFileHandle {
const bytes = lfh.slice();
const new_ptr = try gpa.alignedAlloc(
u8,
@alignOf(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: LinuxFileHandle = .{ .handle = new_header };
@memcpy(new.slice(), lfh.slice());
return new;
}
pub fn destroy(lfh: LinuxFileHandle, 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);
}
pub fn slice(lfh: LinuxFileHandle) []u8 {
const ptr: [*]u8 = &lfh.handle.f_handle;
return ptr[0..lfh.handle.handle_bytes];
}
pub const Adapter = struct {
pub fn hash(self: Adapter, a: LinuxFileHandle) 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: LinuxFileHandle, b: LinuxFileHandle, 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());
}
};
};
pub fn getFileHandle(gpa: Allocator, path: std.Build.Cache.Path, basename: []const u8) !LinuxFileHandle {
var file_handle_buffer: [@sizeOf(std.os.linux.file_handle) + 128]u8 align(@alignOf(std.os.linux.file_handle)) = undefined;
var mount_id: i32 = undefined;
var buf: [std.fs.max_path_bytes]u8 = undefined;
const joined_path = if (path.sub_path.len == 0) basename else path: {
break :path std.fmt.bufPrint(&buf, "{s}/{s}", .{
path.sub_path, basename,
}) 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 std.posix.name_to_handle_at(path.root_dir.handle.fd, joined_path, stack_ptr, &mount_id, 0);
const stack_lfh: LinuxFileHandle = .{ .handle = stack_ptr };
return stack_lfh.clone(gpa);
}
pub fn getDirHandle(gpa: Allocator, path: std.Build.Cache.Path) !LinuxFileHandle {
var file_handle_buffer: [@sizeOf(std.os.linux.file_handle) + 128]u8 align(@alignOf(std.os.linux.file_handle)) = undefined;
var mount_id: i32 = 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 std.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: LinuxFileHandle = .{ .handle = stack_ptr };
return stack_lfh.clone(gpa);
}