add file watcher
This commit is contained in:
parent
08dec6a978
commit
5e09b735c6
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@ -24,6 +24,8 @@ pub fn build(b: *std.Build) void {
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.optimize = optimize,
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.optimize = optimize,
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});
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});
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exe.linkLibC();
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const lib = b.addSharedLibrary(.{
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const lib = b.addSharedLibrary(.{
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.name = "faas-proxy-sample-lib",
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.name = "faas-proxy-sample-lib",
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// In this case the main source file is merely a path, however, in more
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// In this case the main source file is merely a path, however, in more
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@ -60,6 +62,9 @@ pub fn build(b: *std.Build) void {
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run_cmd.addArgs(args);
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run_cmd.addArgs(args);
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}
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}
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const run_step = b.step("run", "Run the app");
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run_step.dependOn(&run_cmd.step);
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// Creates a step for unit testing. This only builds the test executable
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// Creates a step for unit testing. This only builds the test executable
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// but does not run it.
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// but does not run it.
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const main_tests = b.addTest(.{
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const main_tests = b.addTest(.{
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126
src/Watch.zig
Normal file
126
src/Watch.zig
Normal file
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@ -0,0 +1,126 @@
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const builtin = @import("builtin");
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const std = @import("std");
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const c = @cImport({
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@cInclude("poll.h");
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});
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const MAX_FDS = 1024;
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const Self = @This();
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fileChanged: *const fn (usize) void,
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inotify_fd: ?std.os.fd_t = null,
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// sizeof(std.os.pollfd) == 8, so this is 8k
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// fds: [MAX_FDS]std.os.pollfd = [_]std.os.pollfd{.{ .fd = 0, .events = 0, .revents = 0 }} ** MAX_FDS,
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nfds_t: usize = 0,
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wds: [MAX_FDS]i32 = [_]i32{0} ** MAX_FDS,
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modified: [MAX_FDS]bool = [_]bool{false} ** MAX_FDS,
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pub fn init(file_changed: *const fn (usize) void) Self {
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if (builtin.os.tag != .linux)
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@compileError("Unsupported OS");
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return .{
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.fileChanged = file_changed,
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};
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}
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pub fn deinit(self: *Self) void {
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if (self.inotify_fd) |fd| {
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for (self.wds) |wd| {
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const rc = std.os.linux.inotify_rm_watch(fd, wd);
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// Errno can only be EBADF, EINVAL if either the inotify fs or the wd are invalid
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std.debug.assert(rc == 0);
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}
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std.os.close(fd);
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}
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}
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pub fn watchFds(self: *Self) void {
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while (true) {
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if (self.nfds_t == 0) {
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std.time.sleep(250);
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continue;
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}
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var fds = &[_]std.os.pollfd{.{ .fd = self.inotify_fd.?, .events = c.POLLIN, .revents = 0 }};
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// NOTE: There is a std.io.poll that provides a higher level abstraction.
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// However, this API is strictly related to the use case of an open stream
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// for which we are awaiting data. In this case, we are polling for
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// an inotify event, for which no abstraction currently exists
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//
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// std.fs.watch looks really good...but it requires event based I/O,
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// which is not yet ready to be (re)added.
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if ((std.os.poll(
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fds,
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-1, // Infinite timeout
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) catch @panic("poll error")) > 0) {
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if (fds[0].revents & c.POLLIN == c.POLLIN) { // POLLIN means "there is data to read"
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var event_buf: [4096]u8 align(@alignOf(std.os.linux.inotify_event)) = undefined;
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// "borrowed" from https://ziglang.org/documentation/master/std/src/std/fs/watch.zig.html#L588
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const bytes_read = std.os.read(self.inotify_fd.?, &event_buf) catch unreachable;
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var ptr: [*]u8 = &event_buf;
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const end_ptr = ptr + bytes_read;
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while (@ptrToInt(ptr) < @ptrToInt(end_ptr)) {
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const ev = @ptrCast(
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*const std.os.linux.inotify_event,
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@alignCast(@alignOf(*const std.os.linux.inotify_event), ptr),
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);
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if (ev.mask & std.os.linux.IN.MODIFY == std.os.linux.IN.MODIFY) {
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for (self.wds, 0..) |wd, inx| {
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if (ev.wd == wd)
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self.modified[inx] = true;
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}
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}
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// attrib added as build process moves in place and modifies attributes
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// TODO: Also watch MOVED_TO, which is on the directory...
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if (ev.mask & std.os.linux.IN.CLOSE_WRITE == std.os.linux.IN.CLOSE_WRITE or
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ev.mask & std.os.linux.IN.ATTRIB == std.os.linux.IN.ATTRIB)
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{
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for (self.wds, 0..) |wd, inx| {
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if (ev.wd == wd)
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self.fileChanged(inx);
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}
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}
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if (ev.mask & std.os.linux.IN.CLOSE_NOWRITE == std.os.linux.IN.CLOSE_NOWRITE) {
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for (self.wds, 0..) |wd, inx| {
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if (ev.wd == wd and self.modified[inx]) {
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self.modified[inx] = false;
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self.fileChanged(inx);
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}
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}
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}
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// see man 2 poll
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self.handleFile(fds[0]);
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ptr = @alignCast(
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@alignOf(std.os.linux.inotify_event),
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ptr + @sizeOf(std.os.linux.inotify_event) + ev.len,
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);
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}
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}
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}
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}
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}
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pub fn addFileWatch(self: *Self, path: [:0]const u8) !usize {
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self.inotify_fd = self.inotify_fd orelse try std.os.inotify_init1(std.os.linux.IN.NONBLOCK);
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errdefer {
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std.os.close(self.inotify_fd.?);
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self.inotify_fd = null;
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}
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// open 20, close_norite 10, attrib 4
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self.wds[self.nfds_t] = try std.os.inotify_add_watchZ(
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self.inotify_fd.?,
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path,
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std.os.linux.IN.ATTRIB | std.os.linux.IN.CLOSE | std.os.linux.IN.CLOSE_WRITE | std.os.linux.IN.MODIFY,
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);
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if (self.wds[self.nfds_t] == -1)
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@panic("could not set watch");
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self.nfds_t += 1;
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return self.nfds_t - 1;
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}
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fn handleFile(self: Self, fd: std.os.pollfd) void {
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_ = fd;
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_ = self;
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}
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@ -1,6 +1,14 @@
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const std = @import("std");
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const std = @import("std");
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const testing = std.testing;
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const testing = std.testing;
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export fn serve() void {
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const stdout_file = std.io.getStdOut().writer();
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var bw = std.io.bufferedWriter(stdout_file);
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const stdout = bw.writer();
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stdout.print(" 3 ", .{}) catch unreachable;
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bw.flush() catch unreachable;
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}
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export fn add(a: i32, b: i32) i32 {
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export fn add(a: i32, b: i32) i32 {
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return a + b;
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return a + b;
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}
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}
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140
src/main.zig
140
src/main.zig
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@ -1,8 +1,125 @@
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const std = @import("std");
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const std = @import("std");
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const c = @cImport({
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@cInclude("dlfcn.h");
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});
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const Watch = @import("Watch.zig");
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const serve_op = *const fn () void;
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var shutdown = false;
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const timeout = 250;
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const Executor = struct {
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path: [:0]const u8,
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library: ?*anyopaque = null,
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serve: ?serve_op = null,
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watch: ?usize = null,
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};
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var executors = [_]Executor{.{
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.path = "/home/lobo/home/faas-proxy/zig-out/lib/libfaas-proxy-sample-lib.so",
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}};
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var watcher = Watch.init(executorChanged);
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fn serve() !void {
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// if (some path routing thing) {
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(try getExecutor(0))();
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// if (std.c.dlerror()) |_| { // TODO: use capture
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// return error.CouldNotLoadSymbolServe;
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// }
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// TODO: only close on reload
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// if (std.c.dlclose(library.?) != 0) {
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// return error.CouldNotUnloadLibrary;
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// }
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// library = null;
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// }
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}
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fn getExecutor(key: usize) !serve_op {
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var executor = &executors[key];
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if (executor.serve) |s| return s;
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executor.library = blk: {
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if (executor.library) |l| {
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break :blk l;
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}
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const l = try dlopen(executor.path);
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errdefer if (std.c.dlclose(l) != 0)
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@panic("System unstable: Error after library open and cannot close");
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executor.watch = try watcher.addFileWatch(executor.path);
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break :blk l;
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};
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// std.c.dlerror();
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const serve_function = std.c.dlsym(executor.library.?, "serve");
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if (serve_function == null) return error.CouldNotLoadSymbolServe;
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executor.serve = @ptrCast(serve_op, serve_function.?);
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return executor.serve.?;
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}
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// This works
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fn executorChanged(watch: usize) void {
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for (&executors) |*executor| {
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if (executor.watch) |w| {
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if (w == watch) {
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if (executor.library) |l| {
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// TODO: These two lines could introduce a race. Right now that would mean a panic
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executor.serve = null;
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if (std.c.dlclose(l) != 0)
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@panic("System unstable: Error after library open and cannot close");
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}
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executor.library = null;
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executor.serve = null;
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}
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}
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}
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}
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// NOTE: this will be on a different thread. This code does not work, and I
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// am fairly certain it is because we can't share a function pointer between
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// threads
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// fn executorChanged(watch: usize) void {
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// std.debug.print("executor with watch {d} changed\n", .{watch});
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// for (&executors) |*executor| {
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// if (executor.watch) |w| {
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// if (w == watch) {
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// if (executor.library) |l| {
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// std.debug.print("reloading executor at path: {s}\n", .{executor.path});
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// const newlib = dlopen(executor.path) catch {
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// std.debug.print("could not reload! error opening library\n", .{});
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// return;
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// };
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// errdefer if (std.c.dlclose(newlib) != 0)
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// @panic("System unstable: Error after library open and cannot close");
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// const serve_function = std.c.dlsym(newlib, "serve");
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// if (serve_function == null) {
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// std.debug.print("could not reload! error finding symbol\n", .{});
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// return;
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// }
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// // new lib all loaded up - do the swap and close the old
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// std.debug.print("updating function and library\n", .{});
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// executor.serve = @ptrCast(serve_op, serve_function.?);
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// executor.library = newlib;
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// if (std.c.dlclose(l) != 0)
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// @panic("System unstable: Error after library open and cannot close");
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// std.debug.print("closed old library\n", .{});
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// }
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// }
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// }
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// }
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// }
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fn dlopen(path: [:0]const u8) !*anyopaque {
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// We need now (and local) because we're about to call it
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const lib = std.c.dlopen(path, c.RTLD_NOW);
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if (lib) |l| return l;
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return error.CouldNotOpenDynamicLibrary;
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}
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pub fn main() !void {
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pub fn main() !void {
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// Prints to stderr (it's a shortcut based on `std.io.getStdErr()`)
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defer watcher.deinit();
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std.debug.print("All your {s} are belong to us.\n", .{"codebase"});
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// stdout is for the actual output of your application, for example if you
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// stdout is for the actual output of your application, for example if you
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// are implementing gzip, then only the compressed bytes should be sent to
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// are implementing gzip, then only the compressed bytes should be sent to
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@ -11,9 +128,28 @@ pub fn main() !void {
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var bw = std.io.bufferedWriter(stdout_file);
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var bw = std.io.bufferedWriter(stdout_file);
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const stdout = bw.writer();
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const stdout = bw.writer();
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const stderr_file = std.io.getStdErr().writer();
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var bw_stderr = std.io.bufferedWriter(stderr_file);
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const stderr = bw_stderr.writer();
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try stdout.print("Run `zig build test` to run the tests.\n", .{});
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try stdout.print("Run `zig build test` to run the tests.\n", .{});
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try bw.flush(); // don't forget to flush!
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try bw.flush(); // don't forget to flush!
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const watcher_thread = try std.Thread.spawn(.{}, Watch.watchFds, .{&watcher});
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while (true) {
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std.time.sleep(std.time.ns_per_s * 2);
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try stdout.print("Serving...", .{});
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try bw.flush();
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serve() catch |err| {
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try stderr.print("Error serving request ({any})\n", .{err});
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try bw_stderr.flush();
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};
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try stdout.print("served\n", .{});
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try bw.flush();
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}
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shutdown = true;
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watcher_thread.join();
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}
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}
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test "simple test" {
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test "simple test" {
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