FlexiLib/src/main.zig
2023-05-15 19:49:28 -07:00

362 lines
13 KiB
Zig

const std = @import("std");
const builtin = @import("builtin");
const interface = @import("interface.zig");
const Watch = @import("Watch.zig");
const serveFn = *const fn () ?*interface.Response;
const requestDeinitFn = *const fn () void;
const timeout = 250;
const FullReturn = struct {
response: []u8,
executor: *Executor,
};
const Executor = struct {
// configuration
path: [:0]const u8,
// fields used at runtime to do real work
library: ?*anyopaque = null,
serveFn: ?serveFn = null,
requestDeinitFn: ?requestDeinitFn = null,
// fields used for internal accounting
watch: ?usize = null,
reload_lock: bool = false,
in_request_lock: bool = false,
};
// TODO: This should be in a file that maybe gets reloaded with SIGHUP
// rather than a file watch. Touching this config is pretty dangerous
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);
var watcher_thread: ?std.Thread = null;
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 = "handle_request";
const PORT = 8069;
fn serve(allocator: std.mem.Allocator, response: *std.http.Server.Response) !*FullReturn {
// pub const Request = extern struct {
// method: [*]u8,
// method_len: usize,
//
// content: [*]u8,
// content_len: usize,
//
// headers: [*]Header,
// headers_len: usize,
// };
// if (some path routing thing) {
// TODO: Get request body into executor
// TODO: Get headers back from executor
// TODO: Get request headers into executor
const executor = try getExecutor(0);
executor.in_request_lock = true;
errdefer executor.in_request_lock = false;
// Call external library
var serve_result = executor.serveFn.?().?; // ok for this pointer deref to fail
log.debug("target: {s}", .{response.request.target});
log.warn("response ptr: {*}", .{serve_result.ptr}); // BUG: This works in tests, but does not when compiled (even debug mode)
var slice: []u8 = serve_result.ptr[0..serve_result.len];
log.debug("response body: {s}", .{slice});
// Deal with results
var content_type_added = false;
for (0..serve_result.headers_len) |inx| {
const head = serve_result.headers[inx];
// head.name_ptr[0..head.name_len],
try response.headers.append(
head.name_ptr[0..head.name_len],
head.value_ptr[0..head.value_len],
);
// TODO: are these headers case insensitive?
content_type_added = std.mem.eql(u8, head.name_ptr[0..head.name_len], "content-type");
}
if (!content_type_added)
try response.headers.append("content-type", "text/plain");
// target is path
var rc = try allocator.create(FullReturn);
rc.executor = executor;
rc.response = slice;
return rc;
}
fn getExecutor(key: usize) !*Executor {
var executor = &executors[key];
if (executor.serveFn != null) return executor;
executor.library = blk: {
if (executor.library) |l|
break :blk l;
while (executor.reload_lock) // system is reloading the library
std.time.sleep(1 * std.time.ns_per_ms / 2);
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.?);
loadOptionalSymbols(executor);
return executor;
}
fn loadOptionalSymbols(executor: *Executor) void {
if (std.c.dlsym(executor.library.?, "request_deinit")) |s| {
executor.requestDeinitFn = @ptrCast(requestDeinitFn, s);
}
}
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| {
while (executor.in_request_lock)
std.time.sleep(1 * std.time.ns_per_ms / 2);
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;
};
var symbol = std.c.dlsym(executor.library.?, SERVE_FN_NAME);
if (symbol == 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;
}
executor.serveFn = @ptrCast(serveFn, symbol);
loadOptionalSymbols(executor);
}
}
}
}
}
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;
}
// fn exitApplication(sig: i32, info: *const std.os.siginfo_t, ctx_ptr: ?*const anyopaque,) callconv(.C) noreturn {
fn exitApplication(
_: i32,
_: *const std.os.siginfo_t,
_: ?*const anyopaque,
) callconv(.C) noreturn {
exitApp(0);
std.os.exit(0);
}
fn exitApp(exitcode: u8) void {
if (exitcode == 0)
std.io.getStdOut().writer().print("termination request: stopping watch\n", .{}) catch {}
else
std.io.getStdErr().writer().print("abnormal termination: stopping watch\n", .{}) catch {};
watcher.stopWatch() catch @panic("could not stop watcher");
std.io.getStdOut().writer().print("exiting application\n", .{}) catch {};
watcher.deinit();
std.os.exit(exitcode);
// joining threads will hang...we're ultimately in a signal handler.
// But everything is shut down cleanly now, so I don't think it hurts to
// just kill it all
// if (watcher_thread) |t|
// t.join();
}
fn installSignalHandler() !void {
var act = std.os.Sigaction{
.handler = .{ .sigaction = exitApplication },
.mask = std.os.empty_sigset,
.flags = (std.os.SA.SIGINFO | std.os.SA.RESTART | std.os.SA.RESETHAND),
};
try std.os.sigaction(std.os.SIG.INT, &act, null);
try std.os.sigaction(std.os.SIG.TERM, &act, null);
}
pub fn main() !void {
defer exitApp(1);
// 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();
_ = stderr;
try stdout.print("Run `zig build test` to run the tests.\n", .{});
try bw.flush(); // don't forget to flush!
watcher_thread = try std.Thread.spawn(.{}, Watch.startWatch, .{&watcher});
var allocator = std.heap.raw_c_allocator; // raw allocator recommended for use in arenas
var server = std.http.Server.init(allocator, .{ .reuse_address = true });
defer server.deinit();
const address = try std.net.Address.parseIp("0.0.0.0", PORT);
try server.listen(address);
const server_port = server.socket.listen_address.in.getPort();
log.info("listening on port: {d}", .{server_port});
if (builtin.os.tag == .linux)
log.info("pid: {d}", .{std.os.linux.getpid()});
try installSignalHandler();
while (true) {
var arena = std.heap.ArenaAllocator.init(allocator);
defer arena.deinit();
processRequest(arena.allocator(), &server) catch |e| {
log.err("Unexpected error processing request: {any}", .{e});
if (@errorReturnTrace()) |trace| {
std.debug.dumpStackTrace(trace.*);
}
};
}
}
fn processRequest(allocator: std.mem.Allocator, server: *std.http.Server) !void {
const max_header_size = 8192;
const res = try server.accept(.{ .dynamic = max_header_size });
defer res.deinit();
defer res.reset();
try res.wait();
// TODO: deal with this
var buf: [1024]u8 = undefined;
const n = try res.readAll(&buf);
_ = n;
// TODO: we need to also have a defer statement to deinit whatever happens
// with the executor library. This will also add a race condition where
// we could have a memory leak if the executor reloads in the middle of a
// request. We may want to add a new spinlock on the reload thread to
// avoid reloading in the middle of a request, which would be generally
// bad anyway
const errstr = "Internal Server Error\n";
var errbuf: [errstr.len]u8 = undefined;
var response_bytes = try std.fmt.bufPrint(&errbuf, errstr, .{});
var full_response = serve(allocator, res) catch |e| brk: {
res.status = .internal_server_error;
// TODO: more about this particular request
log.err("Unexpected error from executor processing request: {any}", .{e});
if (@errorReturnTrace()) |trace| {
std.debug.dumpStackTrace(trace.*);
}
break :brk null;
};
defer {
if (full_response) |f| {
if (f.executor.requestDeinitFn) |d| d();
f.executor.in_request_lock = false;
}
}
if (full_response) |f|
response_bytes = f.response;
res.transfer_encoding = .{ .content_length = response_bytes.len };
try res.headers.append("connection", "close");
if (builtin.is_test) writeToTestBuffers(response_bytes, res);
try res.do();
_ = try res.writer().writeAll(response_bytes);
try res.finish();
}
fn writeToTestBuffers(response: []const u8, res: *std.http.Server.Response) void {
_ = res;
log.debug("writing to test buffers", .{});
// This performs core dump...because we're in a separate thread?
// @memset(test_resp_buf, 0);
const errmsg = "response exceeds 1024 bytes";
const src = if (response.len < 1024) response else errmsg;
test_resp_buf_len = if (response.len < 1024) response.len else errmsg.len;
for (src, 0..) |b, i| {
test_resp_buf[i] = b;
}
for (test_resp_buf_len..1024) |i| test_resp_buf[i] = 0;
}
fn testRequest(request_bytes: []const u8) !void {
const allocator = std.testing.allocator;
var arena = std.heap.ArenaAllocator.init(allocator);
defer arena.deinit();
var server = std.http.Server.init(allocator, .{ .reuse_address = true });
defer server.deinit();
const address = try std.net.Address.parseIp("127.0.0.1", 0);
try server.listen(address);
const server_port = server.socket.listen_address.in.getPort();
const server_thread = try std.Thread.spawn(
.{},
processRequest,
.{ arena.allocator(), &server },
);
const stream = try std.net.tcpConnectToHost(allocator, "127.0.0.1", server_port);
defer stream.close();
_ = try stream.writeAll(request_bytes[0..]);
server_thread.join();
}
fn testGet(comptime path: []const u8) !void {
try testRequest("GET " ++ path ++ " HTTP/1.1\r\n" ++
"Accept: */*\r\n" ++
"\r\n");
}
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());
}
var test_resp_buf: [1024]u8 = undefined;
var test_resp_buf_len: usize = undefined;
test "root path get" {
std.testing.log_level = .debug;
log.debug("", .{});
try testGet("/");
try std.testing.expectEqual(@as(usize, 3), test_resp_buf_len);
try std.testing.expectEqualStrings(" 2.", test_resp_buf[0..test_resp_buf_len]);
}