diff options
Diffstat (limited to 'libcr_ipc/chan.c')
| -rw-r--r-- | libcr_ipc/chan.c | 146 |
1 files changed, 120 insertions, 26 deletions
diff --git a/libcr_ipc/chan.c b/libcr_ipc/chan.c index 7dd1132..b7ecfc8 100644 --- a/libcr_ipc/chan.c +++ b/libcr_ipc/chan.c @@ -4,37 +4,131 @@ * SPDX-License-Identifier: AGPL-3.0-or-later */ +#include <string.h> /* for memcpy() */ + +#include <libcr/coroutine.h> /* for cid_t, cr_* */ +#include <libmisc/assert.h> +#include <libmisc/rand.h> + +#define IMPLEMENTATION_FOR_LIBCR_IPC_CHAN_H YES #include <libcr_ipc/chan.h> -void _cr_chan_dequeue(void *_ch, size_t) { - struct _cr_chan *ch = _ch; - _cr_ipc_dll_pop_from_front(&ch->waiters); -} +struct _cr_select_waiter { + cid_t cid; + struct _cr_select_arg_list_node *arg_vec; + size_t arg_cnt; -void _cr_chan_xfer(enum _cr_chan_waiter_typ self_typ, struct _cr_chan *ch, void *val_ptr, size_t val_size) { - assert(ch); - assert(val_ptr); + size_t ret; +}; - if (ch->waiters.front && ch->waiter_typ != self_typ) { /* non-blocking fast-path */ - /* Copy. */ - struct _cr_chan_waiter *front = _cr_ipc_dll_node_cast(struct _cr_chan_waiter, ch->waiters.front); - if (self_typ == _CR_CHAN_SENDER) - memcpy(front->val_ptr, val_ptr, val_size); +enum cr_select_class { + CR_SELECT_CLASS_DEFAULT, + CR_SELECT_CLASS_BLOCKING, + CR_SELECT_CLASS_NONBLOCK, +}; + +static inline enum cr_select_class cr_select_getclass(struct _cr_select_arg *arg) { + switch (arg->op) { + case _CR_SELECT_OP_RECV: + if (arg->ch->waiters.front && arg->ch->waiters.front->val.op == _CR_SELECT_OP_SEND) + return CR_SELECT_CLASS_NONBLOCK; + else + return CR_SELECT_CLASS_BLOCKING; + case _CR_SELECT_OP_SEND: + if (arg->ch->waiters.front && arg->ch->waiters.front->val.op == _CR_SELECT_OP_RECV) + return CR_SELECT_CLASS_NONBLOCK; else - memcpy(val_ptr, front->val_ptr, val_size); - cr_unpause(front->cid); - front->dequeue(front->dequeue_arg1, - front->dequeue_arg2); + return CR_SELECT_CLASS_BLOCKING; + case _CR_SELECT_OP_DEFAULT: + return CR_SELECT_CLASS_DEFAULT; + default: + assert_notreached("invalid arg->op"); + } +} + +size_t cr_select_v(size_t arg_cnt, struct _cr_select_arg_list_node arg_vec[]) { + size_t cnt_blocking = 0; + size_t cnt_nonblock = 0; + size_t cnt_default = 0; + + assert(arg_cnt); + assert(arg_vec); + cr_assert_in_coroutine(); + + for (size_t i = 0; i < arg_cnt; i++) { + switch (cr_select_getclass(&arg_vec[i].val)) { + case CR_SELECT_CLASS_BLOCKING: + cnt_blocking++; + break; + case CR_SELECT_CLASS_NONBLOCK: + cnt_nonblock++; + break; + case CR_SELECT_CLASS_DEFAULT: + cnt_default++; + break; + } + } + + if (cnt_nonblock) { + size_t choice_among_nonblock = rand_uint63n(cnt_nonblock); + size_t choice_among_all = arg_cnt; + for (size_t i = 0, seen = 0; i < choice_among_all; i++) { + if (cr_select_getclass(&arg_vec[i].val) == CR_SELECT_CLASS_NONBLOCK) { + if (seen == choice_among_nonblock) + choice_among_all = i; + seen++; + } + } + assert(choice_among_all < arg_cnt); + + struct _cr_select_arg *this = &arg_vec[choice_among_all].val; + assert(this->ch->waiters.front); + struct _cr_select_arg *other = &this->ch->waiters.front->val; + assert(this->val_siz == other->val_siz); + assert(this->ch == other->ch); + switch (this->op) { + case _CR_SELECT_OP_SEND: + assert(other->op == _CR_SELECT_OP_RECV); + memcpy(other->val_ptr, this->val_ptr, this->val_siz); + break; + case _CR_SELECT_OP_RECV: + assert(other->op == _CR_SELECT_OP_SEND); + memcpy(this->val_ptr, other->val_ptr, this->val_siz); + break; + case _CR_SELECT_OP_DEFAULT: + assert_notreached("_CR_SELECT_OP_DEFAULT is not CR_SELECT_CLASS_NONBLOCK"); + } + struct _cr_select_waiter *waiter = other->waiter; + for (size_t i = 0; i < waiter->arg_cnt; i++) { + waiter->arg_vec[i].val.ch->nwaiters--; + dlist_remove(&waiter->arg_vec[i].val.ch->waiters, &waiter->arg_vec[i]); + if (&waiter->arg_vec[i].val == other) + waiter->ret = i; + } + cr_unpause(waiter->cid); cr_yield(); - } else { /* blocking slow-path */ - struct _cr_chan_waiter self = { - .cid = cr_getcid(), - .val_ptr = val_ptr, - .dequeue = _cr_chan_dequeue, - .dequeue_arg1 = ch, - }; - _cr_ipc_dll_push_to_rear(&ch->waiters, &self); - ch->waiter_typ = self_typ; - cr_pause_and_yield(); + return choice_among_all; + } + + if (cnt_default) { + for (size_t i = 0; i < arg_cnt; i++) + if (cr_select_getclass(&arg_vec[i].val) == CR_SELECT_CLASS_DEFAULT) + return i; + assert_notreached("should have returned from inside for() loop"); + } + + assert(cnt_blocking && cnt_blocking == arg_cnt); + + struct _cr_select_waiter waiter = { + .cid = cr_getcid(), + .arg_vec = arg_vec, + .arg_cnt = arg_cnt, + }; + for (size_t i = 0; i < arg_cnt; i++) { + arg_vec[i].val.waiter = &waiter; + arg_vec[i].val.ch->nwaiters++; + dlist_push_to_rear(&arg_vec[i].val.ch->waiters, &arg_vec[i]); } + cr_pause_and_yield(); + return waiter.ret; } |