lobo/FlexiLib
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages 1 Wiki Activity Actions

add file watcher

Browse source
This commit is contained in:
Emil Lerch 2023-05-09 09:18:38 -07:00
parent 08dec6a978
commit 5e09b735c6
Signed by: lobo
GPG key ID: A7B62D657EF764F8
4 changed files with 277 additions and 2 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

5
build.zig
View file

@ -24,6 +24,8 @@ pub fn build(b: *std.Build) void {
.optimize = optimize,
});
exe.linkLibC();
const lib = b.addSharedLibrary(.{
.name = "faas-proxy-sample-lib",
// In this case the main source file is merely a path, however, in more
@ -60,6 +62,9 @@ pub fn build(b: *std.Build) void {
run_cmd.addArgs(args);
}
const run_step = b.step("run", "Run the app");
run_step.dependOn(&run_cmd.step);
// Creates a step for unit testing. This only builds the test executable
// but does not run it.
const main_tests = b.addTest(.{

126
src/Watch.zig Normal file
View file

@ -0,0 +1,126 @@
const builtin = @import("builtin");
const std = @import("std");
const c = @cImport({
@cInclude("poll.h");
});
const MAX_FDS = 1024;
const Self = @This();
fileChanged: *const fn (usize) void,
inotify_fd: ?std.os.fd_t = null,
// sizeof(std.os.pollfd) == 8, so this is 8k
// fds: [MAX_FDS]std.os.pollfd = [_]std.os.pollfd{.{ .fd = 0, .events = 0, .revents = 0 }} ** MAX_FDS,
nfds_t: usize = 0,
wds: [MAX_FDS]i32 = [_]i32{0} ** MAX_FDS,
modified: [MAX_FDS]bool = [_]bool{false} ** MAX_FDS,
pub fn init(file_changed: *const fn (usize) void) Self {
if (builtin.os.tag != .linux)
@compileError("Unsupported OS");
return .{
.fileChanged = file_changed,
};
}
pub fn deinit(self: *Self) void {
if (self.inotify_fd) |fd| {
for (self.wds) |wd| {
const rc = std.os.linux.inotify_rm_watch(fd, wd);
// Errno can only be EBADF, EINVAL if either the inotify fs or the wd are invalid
std.debug.assert(rc == 0);
}
std.os.close(fd);
}
}
pub fn watchFds(self: *Self) void {
while (true) {
if (self.nfds_t == 0) {
std.time.sleep(250);
continue;
}
var fds = &[_]std.os.pollfd{.{ .fd = self.inotify_fd.?, .events = c.POLLIN, .revents = 0 }};
// NOTE: There is a std.io.poll that provides a higher level abstraction.
// However, this API is strictly related to the use case of an open stream
// for which we are awaiting data. In this case, we are polling for
// an inotify event, for which no abstraction currently exists
//
// std.fs.watch looks really good...but it requires event based I/O,
// which is not yet ready to be (re)added.
if ((std.os.poll(
fds,
-1, // Infinite timeout
) catch @panic("poll error")) > 0) {
if (fds[0].revents & c.POLLIN == c.POLLIN) { // POLLIN means "there is data to read"
var event_buf: [4096]u8 align(@alignOf(std.os.linux.inotify_event)) = undefined;
// "borrowed" from https://ziglang.org/documentation/master/std/src/std/fs/watch.zig.html#L588
const bytes_read = std.os.read(self.inotify_fd.?, &event_buf) catch unreachable;
var ptr: [*]u8 = &event_buf;
const end_ptr = ptr + bytes_read;
while (@ptrToInt(ptr) < @ptrToInt(end_ptr)) {
const ev = @ptrCast(
*const std.os.linux.inotify_event,
@alignCast(@alignOf(*const std.os.linux.inotify_event), ptr),
);
if (ev.mask & std.os.linux.IN.MODIFY == std.os.linux.IN.MODIFY) {
for (self.wds, 0..) |wd, inx| {
if (ev.wd == wd)
self.modified[inx] = true;
}
}
// attrib added as build process moves in place and modifies attributes
// TODO: Also watch MOVED_TO, which is on the directory...
if (ev.mask & std.os.linux.IN.CLOSE_WRITE == std.os.linux.IN.CLOSE_WRITE or
ev.mask & std.os.linux.IN.ATTRIB == std.os.linux.IN.ATTRIB)
{
for (self.wds, 0..) |wd, inx| {
if (ev.wd == wd)
self.fileChanged(inx);
}
}
if (ev.mask & std.os.linux.IN.CLOSE_NOWRITE == std.os.linux.IN.CLOSE_NOWRITE) {
for (self.wds, 0..) |wd, inx| {
if (ev.wd == wd and self.modified[inx]) {
self.modified[inx] = false;
self.fileChanged(inx);
}
}
}
// see man 2 poll
self.handleFile(fds[0]);
ptr = @alignCast(
@alignOf(std.os.linux.inotify_event),
ptr + @sizeOf(std.os.linux.inotify_event) + ev.len,
);
}
}
}
}
}
pub fn addFileWatch(self: *Self, path: [:0]const u8) !usize {
self.inotify_fd = self.inotify_fd orelse try std.os.inotify_init1(std.os.linux.IN.NONBLOCK);
errdefer {
std.os.close(self.inotify_fd.?);
self.inotify_fd = null;
}
// open 20, close_norite 10, attrib 4
self.wds[self.nfds_t] = try std.os.inotify_add_watchZ(
self.inotify_fd.?,
path,
std.os.linux.IN.ATTRIB | std.os.linux.IN.CLOSE | std.os.linux.IN.CLOSE_WRITE | std.os.linux.IN.MODIFY,
);
if (self.wds[self.nfds_t] == -1)
@panic("could not set watch");
self.nfds_t += 1;
return self.nfds_t - 1;
}
fn handleFile(self: Self, fd: std.os.pollfd) void {
_ = fd;
_ = self;
}

8
src/main-lib.zig
View file

@ -1,6 +1,14 @@
const std = @import("std");
const testing = std.testing;
export fn serve() void {
const stdout_file = std.io.getStdOut().writer();
var bw = std.io.bufferedWriter(stdout_file);
const stdout = bw.writer();
stdout.print(" 3 ", .{}) catch unreachable;
bw.flush() catch unreachable;
}
export fn add(a: i32, b: i32) i32 {
return a + b;
}

140
src/main.zig
View file

@ -1,8 +1,125 @@
const std = @import("std");
const c = @cImport({
@cInclude("dlfcn.h");
});
const Watch = @import("Watch.zig");
const serve_op = *const fn () void;
var shutdown = false;
const timeout = 250;
const Executor = struct {
path: [:0]const u8,
library: ?*anyopaque = null,
serve: ?serve_op = null,
watch: ?usize = null,
};
var executors = [_]Executor{.{
.path = "/home/lobo/home/faas-proxy/zig-out/lib/libfaas-proxy-sample-lib.so",
}};
var watcher = Watch.init(executorChanged);
fn serve() !void {
// if (some path routing thing) {
(try getExecutor(0))();
// if (std.c.dlerror()) |_| { // TODO: use capture
// return error.CouldNotLoadSymbolServe;
// }
// TODO: only close on reload
// if (std.c.dlclose(library.?) != 0) {
// return error.CouldNotUnloadLibrary;
// }
// library = null;
// }
}
fn getExecutor(key: usize) !serve_op {
var executor = &executors[key];
if (executor.serve) |s| return s;
executor.library = blk: {
if (executor.library) |l| {
break :blk l;
}
const l = try dlopen(executor.path);
errdefer if (std.c.dlclose(l) != 0)
@panic("System unstable: Error after library open and cannot close");
executor.watch = try watcher.addFileWatch(executor.path);
break :blk l;
};
// std.c.dlerror();
const serve_function = std.c.dlsym(executor.library.?, "serve");
if (serve_function == null) return error.CouldNotLoadSymbolServe;
executor.serve = @ptrCast(serve_op, serve_function.?);
return executor.serve.?;
}
// This works
fn executorChanged(watch: usize) void {
for (&executors) |*executor| {
if (executor.watch) |w| {
if (w == watch) {
if (executor.library) |l| {
// TODO: These two lines could introduce a race. Right now that would mean a panic
executor.serve = null;
if (std.c.dlclose(l) != 0)
@panic("System unstable: Error after library open and cannot close");
}
executor.library = null;
executor.serve = null;
}
}
}
}
// NOTE: this will be on a different thread. This code does not work, and I
// am fairly certain it is because we can't share a function pointer between
// threads
// fn executorChanged(watch: usize) void {
// std.debug.print("executor with watch {d} changed\n", .{watch});
// for (&executors) |*executor| {
// if (executor.watch) |w| {
// if (w == watch) {
// if (executor.library) |l| {
// std.debug.print("reloading executor at path: {s}\n", .{executor.path});
// const newlib = dlopen(executor.path) catch {
// std.debug.print("could not reload! error opening library\n", .{});
// return;
// };
// errdefer if (std.c.dlclose(newlib) != 0)
// @panic("System unstable: Error after library open and cannot close");
// const serve_function = std.c.dlsym(newlib, "serve");
// if (serve_function == null) {
// std.debug.print("could not reload! error finding symbol\n", .{});
// return;
// }
// // new lib all loaded up - do the swap and close the old
// std.debug.print("updating function and library\n", .{});
// executor.serve = @ptrCast(serve_op, serve_function.?);
// executor.library = newlib;
// if (std.c.dlclose(l) != 0)
// @panic("System unstable: Error after library open and cannot close");
// std.debug.print("closed old library\n", .{});
// }
// }
// }
// }
// }
fn dlopen(path: [:0]const u8) !*anyopaque {
// We need now (and local) because we're about to call it
const lib = std.c.dlopen(path, c.RTLD_NOW);
if (lib) |l| return l;
return error.CouldNotOpenDynamicLibrary;
}
pub fn main() !void {
// Prints to stderr (it's a shortcut based on `std.io.getStdErr()`)
std.debug.print("All your {s} are belong to us.\n", .{"codebase"});
defer watcher.deinit();
// stdout is for the actual output of your application, for example if you
// are implementing gzip, then only the compressed bytes should be sent to
@ -11,9 +128,28 @@ pub fn main() !void {
var bw = std.io.bufferedWriter(stdout_file);
const stdout = bw.writer();
const stderr_file = std.io.getStdErr().writer();
var bw_stderr = std.io.bufferedWriter(stderr_file);
const stderr = bw_stderr.writer();
try stdout.print("Run `zig build test` to run the tests.\n", .{});
try bw.flush(); // don't forget to flush!
const watcher_thread = try std.Thread.spawn(.{}, Watch.watchFds, .{&watcher});
while (true) {
std.time.sleep(std.time.ns_per_s * 2);
try stdout.print("Serving...", .{});
try bw.flush();
serve() catch |err| {
try stderr.print("Error serving request ({any})\n", .{err});
try bw_stderr.flush();
};
try stdout.print("served\n", .{});
try bw.flush();
}
shutdown = true;
watcher_thread.join();
}
test "simple test" {