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c_api.zig
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c_api.zig
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// This file contains the C bindings that are exported when building
// the system libraries.
//
// WHERE IS THE DOCUMENTATION? Note that all the documentation for the C
// interface is in the man pages. The header file xev.h purposely has no
// documentation so that its concise and easy to see the list of exported
// functions.
const std = @import("std");
const builtin = @import("builtin");
const assert = std.debug.assert;
const xev = @import("main.zig");
export fn xev_loop_init(loop: *xev.Loop) c_int {
// TODO: overflow
loop.* = xev.Loop.init(.{}) catch |err| return errorCode(err);
return 0;
}
export fn xev_loop_deinit(loop: *xev.Loop) void {
loop.deinit();
}
export fn xev_loop_run(loop: *xev.Loop, mode: xev.RunMode) c_int {
loop.run(mode) catch |err| return errorCode(err);
return 0;
}
export fn xev_loop_now(loop: *xev.Loop) i64 {
return loop.now();
}
export fn xev_loop_update_now(loop: *xev.Loop) void {
loop.update_now();
}
export fn xev_completion_zero(c: *xev.Completion) void {
c.* = .{};
}
export fn xev_completion_state(c: *xev.Completion) xev.CompletionState {
return c.state();
}
//-------------------------------------------------------------------
// ThreadPool
export fn xev_threadpool_config_init(cfg: *xev.ThreadPool.Config) void {
cfg.* = .{};
}
export fn xev_threadpool_config_set_stack_size(
cfg: *xev.ThreadPool.Config,
v: u32,
) void {
cfg.stack_size = v;
}
export fn xev_threadpool_config_set_max_threads(
cfg: *xev.ThreadPool.Config,
v: u32,
) void {
cfg.max_threads = v;
}
export fn xev_threadpool_init(
threadpool: *xev.ThreadPool,
cfg_: ?*xev.ThreadPool.Config,
) c_int {
const cfg: xev.ThreadPool.Config = if (cfg_) |v| v.* else .{};
threadpool.* = xev.ThreadPool.init(cfg);
return 0;
}
export fn xev_threadpool_deinit(threadpool: *xev.ThreadPool) void {
threadpool.deinit();
}
export fn xev_threadpool_shutdown(threadpool: *xev.ThreadPool) void {
threadpool.shutdown();
}
export fn xev_threadpool_schedule(
pool: *xev.ThreadPool,
batch: *xev.ThreadPool.Batch,
) void {
pool.schedule(batch.*);
}
export fn xev_threadpool_task_init(
t: *xev.ThreadPool.Task,
cb: *const fn (*xev.ThreadPool.Task) callconv(.C) void,
) void {
const extern_t = @as(*Task, @ptrCast(@alignCast(t)));
extern_t.c_callback = cb;
t.* = .{
.callback = (struct {
fn callback(inner_t: *xev.ThreadPool.Task) void {
const outer_t: *Task = @alignCast(@fieldParentPtr(
"data",
@as(*Task.Data, @ptrCast(inner_t)),
));
outer_t.c_callback(inner_t);
}
}).callback,
};
}
export fn xev_threadpool_batch_init(b: *xev.ThreadPool.Batch) void {
b.* = .{};
}
export fn xev_threadpool_batch_push_task(
b: *xev.ThreadPool.Batch,
t: *xev.ThreadPool.Task,
) void {
b.push(xev.ThreadPool.Batch.from(t));
}
export fn xev_threadpool_batch_push_batch(
b: *xev.ThreadPool.Batch,
other: *xev.ThreadPool.Batch,
) void {
b.push(other.*);
}
//-------------------------------------------------------------------
// Timers
export fn xev_timer_init(v: *xev.Timer) c_int {
v.* = xev.Timer.init() catch |err| return errorCode(err);
return 0;
}
export fn xev_timer_deinit(v: *xev.Timer) void {
v.deinit();
}
export fn xev_timer_run(
v: *xev.Timer,
loop: *xev.Loop,
c: *xev.Completion,
next_ms: u64,
userdata: ?*anyopaque,
cb: *const fn (
*xev.Loop,
*xev.Completion,
c_int,
?*anyopaque,
) callconv(.C) xev.CallbackAction,
) void {
const Callback = @typeInfo(@TypeOf(cb)).Pointer.child;
const extern_c = @as(*Completion, @ptrCast(@alignCast(c)));
extern_c.c_callback = @as(*const anyopaque, @ptrCast(cb));
v.run(loop, c, next_ms, anyopaque, userdata, (struct {
fn callback(
ud: ?*anyopaque,
cb_loop: *xev.Loop,
cb_c: *xev.Completion,
r: xev.Timer.RunError!void,
) xev.CallbackAction {
const cb_extern_c = @as(*Completion, @ptrCast(cb_c));
const cb_c_callback = @as(
*const Callback,
@ptrCast(@alignCast(cb_extern_c.c_callback)),
);
return @call(.auto, cb_c_callback, .{
cb_loop,
cb_c,
if (r) |_| 0 else |err| errorCode(err),
ud,
});
}
}).callback);
}
export fn xev_timer_reset(
v: *xev.Timer,
loop: *xev.Loop,
c: *xev.Completion,
c_cancel: *xev.Completion,
next_ms: u64,
userdata: ?*anyopaque,
cb: *const fn (
*xev.Loop,
*xev.Completion,
c_int,
?*anyopaque,
) callconv(.C) xev.CallbackAction,
) void {
const Callback = @typeInfo(@TypeOf(cb)).Pointer.child;
const extern_c = @as(*Completion, @ptrCast(@alignCast(c)));
extern_c.c_callback = @as(*const anyopaque, @ptrCast(cb));
v.reset(loop, c, c_cancel, next_ms, anyopaque, userdata, (struct {
fn callback(
ud: ?*anyopaque,
cb_loop: *xev.Loop,
cb_c: *xev.Completion,
r: xev.Timer.RunError!void,
) xev.CallbackAction {
const cb_extern_c = @as(*Completion, @ptrCast(cb_c));
const cb_c_callback = @as(
*const Callback,
@ptrCast(@alignCast(cb_extern_c.c_callback)),
);
return @call(.auto, cb_c_callback, .{
cb_loop,
cb_c,
if (r) |_| 0 else |err| errorCode(err),
ud,
});
}
}).callback);
}
export fn xev_timer_cancel(
v: *xev.Timer,
loop: *xev.Loop,
c_timer: *xev.Completion,
c_cancel: *xev.Completion,
userdata: ?*anyopaque,
cb: *const fn (
*xev.Loop,
*xev.Completion,
c_int,
?*anyopaque,
) callconv(.C) xev.CallbackAction,
) void {
const Callback = @typeInfo(@TypeOf(cb)).Pointer.child;
const extern_c = @as(*Completion, @ptrCast(@alignCast(c_cancel)));
extern_c.c_callback = @as(*const anyopaque, @ptrCast(cb));
v.cancel(loop, c_timer, c_cancel, anyopaque, userdata, (struct {
fn callback(
ud: ?*anyopaque,
cb_loop: *xev.Loop,
cb_c: *xev.Completion,
r: xev.Timer.CancelError!void,
) xev.CallbackAction {
const cb_extern_c = @as(*Completion, @ptrCast(cb_c));
const cb_c_callback = @as(
*const Callback,
@ptrCast(@alignCast(cb_extern_c.c_callback)),
);
return @call(.auto, cb_c_callback, .{
cb_loop,
cb_c,
if (r) |_| 0 else |err| errorCode(err),
ud,
});
}
}).callback);
}
//-------------------------------------------------------------------
// Async
export fn xev_async_init(v: *xev.Async) c_int {
v.* = xev.Async.init() catch |err| return errorCode(err);
return 0;
}
export fn xev_async_deinit(v: *xev.Async) void {
v.deinit();
}
export fn xev_async_notify(v: *xev.Async) c_int {
v.notify() catch |err| return errorCode(err);
return 0;
}
export fn xev_async_wait(
v: *xev.Async,
loop: *xev.Loop,
c: *xev.Completion,
userdata: ?*anyopaque,
cb: *const fn (
*xev.Loop,
*xev.Completion,
c_int,
?*anyopaque,
) callconv(.C) xev.CallbackAction,
) void {
const Callback = @typeInfo(@TypeOf(cb)).Pointer.child;
const extern_c = @as(*Completion, @ptrCast(@alignCast(c)));
extern_c.c_callback = @as(*const anyopaque, @ptrCast(cb));
v.wait(loop, c, anyopaque, userdata, (struct {
fn callback(
ud: ?*anyopaque,
cb_loop: *xev.Loop,
cb_c: *xev.Completion,
r: xev.Async.WaitError!void,
) xev.CallbackAction {
const cb_extern_c = @as(*Completion, @ptrCast(cb_c));
const cb_c_callback = @as(
*const Callback,
@ptrCast(@alignCast(cb_extern_c.c_callback)),
);
return @call(.auto, cb_c_callback, .{
cb_loop,
cb_c,
if (r) |_| 0 else |err| errorCode(err),
ud,
});
}
}).callback);
}
//-------------------------------------------------------------------
// Sync with xev.h
/// Since we can't pass the callback at comptime with C, we have to
/// have an additional field on completions to store our callback pointer.
/// We just tack it onto the end of the memory chunk that C programs allocate
/// for completions.
const Completion = extern struct {
const Data = [@sizeOf(xev.Completion)]u8;
data: Data,
c_callback: *const anyopaque,
};
const Task = extern struct {
const Data = [@sizeOf(xev.ThreadPool.Task)]u8;
data: Data,
c_callback: *const fn (*xev.ThreadPool.Task) callconv(.C) void,
};
/// Returns the unique error code for an error.
fn errorCode(err: anyerror) c_int {
// TODO(mitchellh): This is a bad idea because its not stable across
// code changes. For now we just document that error codes are not
// stable but that is not useful at all!
return @intFromError(err);
}
test "c-api sizes" {
// This tests the sizes that are defined in the C API. We must ensure
// that our main structure sizes never exceed these so that the C ABI
// is maintained.
//
// THE MAGIC NUMBERS ARE KEPT IN SYNC WITH "include/xev.h"
const testing = std.testing;
try testing.expect(@sizeOf(xev.Loop) <= 512);
try testing.expect(@sizeOf(Completion) <= 320);
try testing.expect(@sizeOf(xev.Async) <= 256);
try testing.expect(@sizeOf(xev.Timer) <= 256);
try testing.expectEqual(@as(usize, 48), @sizeOf(xev.ThreadPool));
try testing.expectEqual(@as(usize, 24), @sizeOf(xev.ThreadPool.Batch));
try testing.expectEqual(@as(usize, 24), @sizeOf(Task));
try testing.expectEqual(@as(usize, 8), @sizeOf(xev.ThreadPool.Config));
}