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unix/moduselect: Implement ipoll() method with no-allocation policy.

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ipoll() allows to poll streams without allocating any memory: this method
returns an iterator (a poll object itself), and the iterator yields
preallocated "callee-owned tuple" with polling results for each active
stream. The only operation a caller is allowed to do with this tuple is
extracting values from it (storing the tuple as a whole somewhere is
not allowed).
This commit is contained in:
Paul Sokolovsky 2017-02-13 00:23:23 +03:00
parent aac2db9aaf
commit 16a3534ad4
1 changed files with 72 additions and 5 deletions
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77
unix/moduselect.c
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@ -4,7 +4,7 @@
* The MIT License (MIT)
*
* Copyright (c) 2014 Damien P. George
* Copyright (c) 2015 Paul Sokolovsky
* Copyright (c) 2015-2017 Paul Sokolovsky
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
@ -55,6 +55,11 @@ typedef struct _mp_obj_poll_t {
unsigned short len;
struct pollfd *entries;
mp_obj_t *obj_map;
short iter_cnt;
short iter_idx;
int flags;
// callee-owned tuple
mp_obj_t ret_tuple;
} mp_obj_poll_t;
STATIC int get_fd(mp_obj_t fdlike) {
@ -164,9 +169,7 @@ STATIC mp_obj_t poll_modify(mp_obj_t self_in, mp_obj_t obj_in, mp_obj_t eventmas
}
MP_DEFINE_CONST_FUN_OBJ_3(poll_modify_obj, poll_modify);
/// \method poll([timeout])
/// Timeout is in milliseconds.
STATIC mp_obj_t poll_poll(size_t n_args, const mp_obj_t *args) {
STATIC int poll_poll_internal(size_t n_args, const mp_obj_t *args) {
mp_obj_poll_t *self = MP_OBJ_TO_PTR(args[0]);
// work out timeout (it's given already in ms)
@ -184,12 +187,24 @@ STATIC mp_obj_t poll_poll(size_t n_args, const mp_obj_t *args) {
}
}
self->flags = flags;
int n_ready = poll(self->entries, self->len, timeout);
RAISE_ERRNO(n_ready, errno);
return n_ready;
}
/// \method poll([timeout])
/// Timeout is in milliseconds.
STATIC mp_obj_t poll_poll(size_t n_args, const mp_obj_t *args) {
int n_ready = poll_poll_internal(n_args, args);
if (n_ready == 0) {
return mp_const_empty_tuple;
}
mp_obj_poll_t *self = MP_OBJ_TO_PTR(args[0]);
mp_obj_list_t *ret_list = MP_OBJ_TO_PTR(mp_obj_new_list(n_ready, NULL));
int ret_i = 0;
struct pollfd *entries = self->entries;
@ -204,7 +219,7 @@ STATIC mp_obj_t poll_poll(size_t n_args, const mp_obj_t *args) {
}
t->items[1] = MP_OBJ_NEW_SMALL_INT(entries->revents);
ret_list->items[ret_i++] = MP_OBJ_FROM_PTR(t);
if (flags & FLAG_ONESHOT) {
if (self->flags & FLAG_ONESHOT) {
entries->events = 0;
}
}
@ -214,17 +229,67 @@ STATIC mp_obj_t poll_poll(size_t n_args, const mp_obj_t *args) {
}
MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(poll_poll_obj, 1, 3, poll_poll);
STATIC mp_obj_t poll_ipoll(size_t n_args, const mp_obj_t *args) {
mp_obj_poll_t *self = MP_OBJ_TO_PTR(args[0]);
if (self->ret_tuple == MP_OBJ_NULL) {
self->ret_tuple = mp_obj_new_tuple(2, NULL);
}
int n_ready = poll_poll_internal(n_args, args);
self->iter_cnt = n_ready;
self->iter_idx = 0;
return args[0];
}
MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(poll_ipoll_obj, 1, 3, poll_ipoll);
STATIC mp_obj_t poll_iternext(mp_obj_t self_in) {
mp_obj_poll_t *self = MP_OBJ_TO_PTR(self_in);
if (self->iter_cnt == 0) {
return MP_OBJ_STOP_ITERATION;
}
self->iter_cnt--;
struct pollfd *entries = self->entries;
for (int i = self->iter_idx; i < self->len; i++, entries++) {
if (entries->revents != 0) {
mp_obj_tuple_t *t = MP_OBJ_TO_PTR(self->ret_tuple);
// If there's an object stored, return it, otherwise raw fd
if (self->obj_map && self->obj_map[i] != MP_OBJ_NULL) {
t->items[0] = self->obj_map[i];
} else {
t->items[0] = MP_OBJ_NEW_SMALL_INT(entries->fd);
}
t->items[1] = MP_OBJ_NEW_SMALL_INT(entries->revents);
if (self->flags & FLAG_ONESHOT) {
entries->events = 0;
}
return MP_OBJ_FROM_PTR(t);
}
}
assert(!"inconsistent number of poll active entries");
self->iter_cnt = 0;
return MP_OBJ_STOP_ITERATION;
}
STATIC const mp_rom_map_elem_t poll_locals_dict_table[] = {
{ MP_ROM_QSTR(MP_QSTR_register), MP_ROM_PTR(&poll_register_obj) },
{ MP_ROM_QSTR(MP_QSTR_unregister), MP_ROM_PTR(&poll_unregister_obj) },
{ MP_ROM_QSTR(MP_QSTR_modify), MP_ROM_PTR(&poll_modify_obj) },
{ MP_ROM_QSTR(MP_QSTR_poll), MP_ROM_PTR(&poll_poll_obj) },
{ MP_ROM_QSTR(MP_QSTR_ipoll), MP_ROM_PTR(&poll_ipoll_obj) },
};
STATIC MP_DEFINE_CONST_DICT(poll_locals_dict, poll_locals_dict_table);
STATIC const mp_obj_type_t mp_type_poll = {
{ &mp_type_type },
.name = MP_QSTR_poll,
.getiter = mp_identity,
.iternext = poll_iternext,
.locals_dict = (void*)&poll_locals_dict,
};
@ -239,6 +304,8 @@ STATIC mp_obj_t select_poll(size_t n_args, const mp_obj_t *args) {
poll->alloc = alloc;
poll->len = 0;
poll->obj_map = NULL;
poll->iter_cnt = 0;
poll->ret_tuple = MP_OBJ_NULL;
return MP_OBJ_FROM_PTR(poll);
}
MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(mp_select_poll_obj, 0, 1, select_poll);