picoev, picohttparser: reimplement in V (#18506)

vlib/picoev/loop_freebsd.c.v

@@ -0,0 +1,203 @@
+module picoev
+
+#include <errno.h>
+#include <sys/types.h>
+#include <sys/event.h>
+
+fn C.kevent(int, changelist voidptr, nchanges int, eventlist voidptr, nevents int, timout &C.timespec) int
+fn C.kqueue() int
+fn C.EV_SET(kev voidptr, ident int, filter i16, flags u16, fflags u32, data voidptr, udata voidptr)
+
+pub struct C.kevent {
+pub mut:
+	ident int
+	// uintptr_t
+	filter i16
+	flags  u16
+	fflags u32
+	data   voidptr
+	// intptr_t
+	udata voidptr
+}
+
+[heap]
+pub struct KqueueLoop {
+mut:
+	id    int
+	now   i64
+	kq_id int
+	// -1 if not changed
+	changed_fds int
+	events      [1024]C.kevent
+	changelist  [256]C.kevent
+}
+
+type LoopType = KqueueLoop
+
+// create_kqueue_loop creates a new kernel event queue with loop_id=`id`
+pub fn create_kqueue_loop(id int) !&KqueueLoop {
+	mut loop := &KqueueLoop{
+		id: id
+	}
+
+	loop.kq_id = C.kqueue()
+	if loop.kq_id == -1 {
+		return error('could not create kqueue loop!')
+	}
+	loop.changed_fds = -1
+	return loop
+}
+
+// ev_set sets a new `kevent` with file descriptor `index`
+[inline]
+pub fn (mut pv Picoev) ev_set(index int, operation int, events int) {
+	// vfmt off
+	filter := i16(
+		(if events & picoev_read != 0 { C.EVFILT_READ } else { 0 })
+			|
+		(if events & picoev_write != 0 { C.EVFILT_WRITE } else { 0 })
+	)
+	// vfmt on
+	C.EV_SET(&pv.loop.changelist[index], pv.loop.changed_fds, filter, operation, 0, 0,
+		0)
+}
+
+// backend_build uses the lower 8 bits to store the old events and the higher 8
+// bits to store the next file descriptor in `Target.backend`
+[inline]
+fn backend_build(next_fd int, events u32) int {
+	return int((u32(next_fd) << 8) | (events & 0xff))
+}
+
+// get the lower 8 bits
+[inline]
+fn backend_get_old_events(backend int) int {
+	return backend & 0xff
+}
+
+// get the higher 8 bits
+[inline]
+fn backend_get_next_fd(backend int) int {
+	return backend >> 8
+}
+
+// apply pending processes all changes for the file descriptors and updates `loop.changelist`
+// if `aplly_all` is `true` the changes are immediately applied
+fn (mut pv Picoev) apply_pending_changes(apply_all bool) int {
+	mut total, mut nevents := 0, 0
+
+	for pv.loop.changed_fds != -1 {
+		mut target := pv.file_descriptors[pv.loop.changed_fds]
+		old_events := backend_get_old_events(target.backend)
+		if target.events != old_events {
+			// events have been changed
+			if old_events != 0 {
+				pv.ev_set(total, C.EV_DISABLE, old_events)
+				total++
+			}
+			if target.events != 0 {
+				pv.ev_set(total, C.EV_ADD | C.EV_ENABLE, int(target.events))
+				total++
+			}
+			// Apply the changes if the total changes exceed the changelist size
+			if total + 1 >= pv.loop.changelist.len {
+				nevents = C.kevent(pv.loop.kq_id, &pv.loop.changelist, total, C.NULL,
+					0, C.NULL)
+				assert nevents == 0
+				total = 0
+			}
+		}
+
+		pv.loop.changed_fds = backend_get_next_fd(target.backend)
+		target.backend = -1
+	}
+
+	if apply_all && total != 0 {
+		nevents = C.kevent(pv.loop.kq_id, &pv.loop.changelist, total, C.NULL, 0, C.NULL)
+		assert nevents == 0
+		total = 0
+	}
+
+	return total
+}
+
+[direct_array_access]
+fn (mut pv Picoev) update_events(fd int, events int) int {
+	// check if fd is in range
+	assert fd < max_fds
+
+	mut target := pv.file_descriptors[fd]
+
+	// initialize if adding the fd
+	if events & picoev_add != 0 {
+		target.backend = -1
+	}
+
+	// return if nothing to do
+	if (events == picoev_del && target.backend == -1)
+		|| (events != picoev_del && events & picoev_readwrite == target.events) {
+		return 0
+	}
+
+	// add to changed list if not yet being done
+	if target.backend == -1 {
+		target.backend = backend_build(pv.loop.changed_fds, target.events)
+		pv.loop.changed_fds = fd
+	}
+
+	// update events
+	target.events = u32(events & picoev_readwrite)
+	// apply immediately if is a DELETE
+	if events & picoev_del != 0 {
+		pv.apply_pending_changes(true)
+	}
+
+	return 0
+}
+
+[direct_array_access]
+fn (mut pv Picoev) poll_once(max_wait int) int {
+	ts := C.timespec{
+		tv_sec: max_wait
+		tv_nsec: 0
+	}
+
+	mut total, mut nevents := 0, 0
+	// apply changes later when the callback is called.
+	total = pv.apply_pending_changes(false)
+
+	nevents = C.kevent(pv.loop.kq_id, &pv.loop.changelist, total, &pv.loop.events, pv.loop.events.len,
+		&ts)
+	if nevents == -1 {
+		// the errors we can only rescue
+		assert C.errno == C.EACCES || C.errno == C.EFAULT || C.errno == C.EINTR
+		return -1
+	}
+
+	for i := 0; i < nevents; i++ {
+		event := pv.loop.events[i]
+		target := pv.file_descriptors[event.ident]
+
+		// changelist errors are fatal
+		assert event.flags & C.EV_ERROR == 0
+
+		if pv.loop.id == target.loop_id && event.filter & (C.EVFILT_READ | C.EVFILT_WRITE) != 0 {
+			read_events := match int(event.filter) {
+				C.EVFILT_READ {
+					picoev_read
+				}
+				C.EVFILT_WRITE {
+					picoev_write
+				}
+				else {
+					0
+				}
+			}
+
+			// do callback!
+			unsafe { target.cb(target.fd, read_events, &pv) }
+		}
+	}
+
+	return 0
+}