FlexiLib/src/main.zig
2023-05-11 10:12:37 -07:00

164 lines
5.5 KiB
Zig

const std = @import("std");
const Watch = @import("Watch.zig");
const serveFn = *const fn () void;
var shutdown = false;
const timeout = 250;
const Executor = struct {
path: [:0]const u8,
library: ?*anyopaque = null,
serveFn: ?serveFn = null,
watch: ?usize = null,
reload_lock: bool = false,
};
var executors = [_]Executor{
.{ .path = "zig-out/lib/libfaas-proxy-sample-lib.so" },
.{ .path = "zig-out/lib/libfaas-proxy-sample-lib2.so" },
};
var watcher = Watch.init(executorChanged);
const log = std.log.scoped(.main);
pub const std_options = struct {
pub const log_level = .debug;
pub const log_scope_levels = &[_]std.log.ScopeLevel{
.{ .scope = .watch, .level = .info },
};
};
const SERVE_FN_NAME = "serve";
fn serve() !void {
// if (some path routing thing) {
(try getExecutor(0))();
// if (inx > 4) {
// if (inx % 2 == 0)
// (try getExecutor(0))()
// else
// (try getExecutor(1))();
// }
}
fn getExecutor(key: usize) !serveFn {
var executor = &executors[key];
if (executor.serveFn) |s| return s;
executor.library = blk: {
if (executor.library) |l|
break :blk l;
while (executor.reload_lock) // system is reloading the library
std.time.sleep(1);
if (executor.library) |l| // check again to see where we are at
break :blk l;
log.info("library {s} requested but not loaded. Loading library", .{executor.path});
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 = executor.watch orelse try watcher.addFileWatch(&executor.path);
break :blk l;
};
// std.c.dlerror();
const serve_fn = std.c.dlsym(executor.library.?, SERVE_FN_NAME);
if (serve_fn == null) return error.CouldNotLoadSymbolServe;
executor.serveFn = @ptrCast(serveFn, serve_fn.?);
return executor.serveFn.?;
}
fn executorChanged(watch: usize) void {
// NOTE: This will be called off the main thread
log.debug("executor with watch {d} changed", .{watch});
for (&executors) |*executor| {
if (executor.watch) |w| {
if (w == watch) {
if (executor.library) |l| {
executor.reload_lock = true;
defer executor.reload_lock = false;
if (std.c.dlclose(l) != 0)
@panic("System unstable: Error after library open and cannot close");
log.debug("closed old library. reloading executor at: {s}", .{executor.path});
executor.library = dlopen(executor.path) catch {
log.warn("could not reload! error opening library", .{});
return;
};
executor.serveFn = @ptrCast(serveFn, std.c.dlsym(executor.library.?, SERVE_FN_NAME));
if (executor.serveFn == null) {
log.warn("could not reload! error finding symbol", .{});
if (std.c.dlclose(executor.library.?) != 0)
@panic("System unstable: Error after library open and cannot close");
return;
}
}
}
}
}
}
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, std.c.RTLD.NOW);
if (lib) |l| return l;
return error.CouldNotOpenDynamicLibrary;
}
var inx: usize = 0;
pub fn main() !void {
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
// stdout, not any debugging messages.
const stdout_file = std.io.getStdOut().writer();
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.startWatch, .{&watcher});
while (true) {
std.time.sleep(std.time.ns_per_s * 2);
inx += 1;
if (inx == 10) {
log.debug("forcing stop to make sure it works", .{});
try watcher.stopWatch();
break;
}
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 {
// To run nested container tests, either, call `refAllDecls` which will
// reference all declarations located in the given argument.
// `@This()` is a builtin function that returns the innermost container it is called from.
// In this example, the innermost container is this file (implicitly a struct).
std.testing.refAllDecls(@This());
}
test "simple test" {
var list = std.ArrayList(i32).init(std.testing.allocator);
defer list.deinit(); // try commenting this out and see if zig detects the memory leak!
try list.append(42);
try std.testing.expectEqual(@as(i32, 42), list.pop());
}