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https://github.com/alsa-project/alsa-utils
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cd211d8c22
There're several types of system calls for multiplexed I/O. They're used to receive notifications of I/O events. Typically, userspace applications call them against file descriptor to yield CPU. When I/O is enabled on any of the descriptors, a task of the application is rescheduled, then the application execute I/O calls. This commit adds a common interface for this type of system calls, named as 'waiter'. This is expected to be used with non-blocking file operation and operations on mapped page frame. Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp> Signed-off-by: Takashi Iwai <tiwai@suse.de>
99 lines
2 KiB
C
99 lines
2 KiB
C
// SPDX-License-Identifier: GPL-2.0
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//
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// waiter.c - I/O event waiter.
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//
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// Copyright (c) 2018 Takashi Sakamoto <o-takashi@sakamocchi.jp>
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//
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// Licensed under the terms of the GNU General Public License, version 2.
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#include "waiter.h"
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#include <stdlib.h>
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#include <string.h>
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#include <errno.h>
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#include "misc.h"
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static const char *const waiter_type_labels[] = {
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[WAITER_TYPE_DEFAULT] = "default",
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};
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enum waiter_type waiter_type_from_label(const char *label)
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{
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int i;
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for (i = 0; i < ARRAY_SIZE(waiter_type_labels); ++i) {
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if (!strcmp(waiter_type_labels[i], label))
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return i;
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}
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return WAITER_TYPE_DEFAULT;
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}
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const char *waiter_label_from_type(enum waiter_type type)
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{
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return waiter_type_labels[type];
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}
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int waiter_context_init(struct waiter_context *waiter,
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enum waiter_type type, unsigned int pfd_count)
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{
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struct {
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enum waiter_type type;
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const struct waiter_data *waiter;
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} entries[] = {
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{WAITER_TYPE_COUNT, NULL},
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};
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int i;
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if (pfd_count == 0)
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return -EINVAL;
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for (i = 0; i < ARRAY_SIZE(entries); ++i) {
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if (entries[i].type == type)
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break;
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}
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if (i == ARRAY_SIZE(entries))
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return -EINVAL;
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waiter->private_data = malloc(entries[i].waiter->private_size);
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if (waiter->private_data == NULL)
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return -ENOMEM;
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memset(waiter->private_data, 0, entries[i].waiter->private_size);
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waiter->type = type;
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waiter->ops = &entries[i].waiter->ops;
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waiter->pfds = calloc(pfd_count, sizeof(*waiter->pfds));
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if (waiter->pfds == NULL)
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return -ENOMEM;
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waiter->pfd_count = pfd_count;
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return 0;
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}
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int waiter_context_prepare(struct waiter_context *waiter)
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{
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return waiter->ops->prepare(waiter);
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}
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int waiter_context_wait_event(struct waiter_context *waiter,
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int timeout_msec)
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{
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return waiter->ops->wait_event(waiter, timeout_msec);
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}
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void waiter_context_release(struct waiter_context *waiter)
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{
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waiter->ops->release(waiter);
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}
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void waiter_context_destroy(struct waiter_context *waiter)
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{
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if (waiter->pfds)
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free(waiter->pfds);
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waiter->pfd_count = 0;
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if (waiter->private_data)
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free(waiter->private_data);
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waiter->private_data = NULL;
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}
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