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102 lines
2.7 KiB
C
102 lines
2.7 KiB
C
/* Copyright (C) 2021,2022 fef <owo@fef.moe>. All rights reserved. */
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#pragma once
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#include <arch/atom.h>
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#include <gay/mm.h>
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#include <gay/types.h>
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#include <gay/util.h>
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/**
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* @defgroup kqueue Lock Free FIFO (kqueue)
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*
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* kqueue is a simple API that allows any structure to become part of a
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* lock-free FIFO queue. It only uses atomic primitives and spin-wait loops,
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* which makes it safe to use even from irq context. Furthermore, it supports
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* multiple concurrent emitters *and* consumers, making it suitable for stuff
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* like serving as the backend for a basic batch processing system distributed
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* across several CPUs.
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*
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* @{
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*/
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/** @brief Embed this into structs that you want to put in a kqueue. */
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struct kq_node {
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patom_t next;
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};
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/** @brief Lock free FIFO with support for multiple emitters and consumers. */
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struct kqueue {
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patom_t head;
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patom_t tail;
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struct kq_node _dummy;
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};
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/**
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* @brief Initialize a kqueue.
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*
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* @param kq kqueue to initialize
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*/
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static inline void kq_init(struct kqueue *kq)
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{
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patom_init(&kq->head, &kq->_dummy);
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patom_init(&kq->tail, &kq->_dummy);
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patom_init(&kq->_dummy.next, nil);
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}
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/**
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* @brief Allocate a new kqueue and initialize it.
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*
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* @param flags Flags for `kmalloc()`
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* @return The initialized kqueue, or `nil` if OOM
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*/
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struct kqueue *kq_create(enum mflags flags);
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/**
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* @brief Add a new entry to the end of a kqueue.
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*
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* @param kq kqueue to append the entry to
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* @param node New node to append to the queue
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*/
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void kq_add(struct kqueue *kq, struct kq_node *node);
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/**
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* @brief Remove the first item in a kqueue.
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*
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* @param kq kqueue to remove an item from
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* @return The removed item, or `nil` if the queue was empty
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*/
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struct kq_node *kq_del(struct kqueue *kq);
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/**
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* @brief Cast a kqueue entry out to the structure it is embedded in.
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*
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* @param head The `kq_node_t *` to cast out of
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* @param type Type of the containing structure
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* @param member Name of the `kq_node_t` within the structure
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* @returns The `struct *` that `head` is embedded in
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*/
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#define kq_entry(head, type, member) container_of(head, type, member)
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/**
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* @brief Remove the first item in a kqueue and return the structure
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* it is embedded in.
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*
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* @param kq kqueue to remove an item from
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* @param type Type of the containing structure
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* @param member Name of the `kq_node_t` within the structure
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* @returns The `struct *` that was removed from the queue,
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* or `nil` if the queue was empty
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*/
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#define kq_del_entry(kq, type, member) ({ \
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struct kq_node *__node = kq_del(kq); \
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/* NOLINTNEXTLINE(bugprone-macro-parentheses) */ \
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type *__entry = nil; \
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if (__node != nil) \
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__entry = kq_entry(__node, type, member); \
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__entry; \
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})
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/** @} */
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