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利用C語言實(shí)現(xiàn)經(jīng)典多級(jí)時(shí)間輪定時(shí)器

更新時(shí)間：2021年07月14日 11:40:46 作者：叨陪鯉

C語言是一門通用計(jì)算機(jī)編程語言,廣泛應(yīng)用于底層開發(fā),這篇文章主要給大家介紹了關(guān)于利用C語言實(shí)現(xiàn)經(jīng)典多級(jí)時(shí)間輪定時(shí)器的相關(guān)資料,需要的朋友可以參考下

1. 序言

最近一直在找時(shí)間輪的C語言實(shí)現(xiàn)代碼，發(fā)現(xiàn)很多都是Java或者c++實(shí)現(xiàn)的。而我對(duì)其他語言不熟悉，看不太懂。關(guān)于C實(shí)現(xiàn)的，讓我如沐春風(fēng)的實(shí)現(xiàn)沒找到，github上也只找打一個(gè)135星的項(xiàng)目，它的具體實(shí)現(xiàn)還沒來得及看。后來經(jīng)過多方搜索，找到了兩個(gè)比較類似的代碼，博主都稱參考Linux源碼中的實(shí)現(xiàn)，但是我沒有找到對(duì)應(yīng)的代碼，個(gè)人感覺他們代碼實(shí)現(xiàn)的很好，經(jīng)過整理后再次分享出來供以后學(xué)習(xí)（反正我自己寫不出來，我嘗試寫了一個(gè)簡單時(shí)間輪的代碼，是在不敢直視）。

2. 多級(jí)時(shí)間輪實(shí)現(xiàn)框架

上圖是5個(gè)時(shí)間輪級(jí)聯(lián)的效果圖。中間的大輪是工作輪，只有在它上的任務(wù)才會(huì)被執(zhí)行；其他輪上的任務(wù)時(shí)間到后遷移到下一級(jí)輪上，他們最終都會(huì)遷移到工作輪上而被調(diào)度執(zhí)行。

多級(jí)時(shí)間輪的原理也容易理解：就拿時(shí)鐘做說明，秒針轉(zhuǎn)動(dòng)一圈分針轉(zhuǎn)動(dòng)一格；分針轉(zhuǎn)動(dòng)一圈時(shí)針轉(zhuǎn)動(dòng)一格；同理時(shí)間輪也是如此：當(dāng)?shù)图?jí)輪轉(zhuǎn)動(dòng)一圈時(shí)，高一級(jí)輪轉(zhuǎn)動(dòng)一格，同時(shí)會(huì)將高一級(jí)輪上的任務(wù)重新分配到低級(jí)輪上。從而實(shí)現(xiàn)了多級(jí)輪級(jí)聯(lián)的效果。

2.1 多級(jí)時(shí)間輪對(duì)象

多級(jí)時(shí)間輪應(yīng)該至少包括以下內(nèi)容：

每一級(jí)時(shí)間輪對(duì)象
輪子上指針的位置

關(guān)于輪子上指針的位置有一個(gè)比較巧妙的辦法：那就是位運(yùn)算。比如定義一個(gè)無符號(hào)整型的數(shù)：

==通過獲取當(dāng)前的系統(tǒng)時(shí)間便可以通過位操作轉(zhuǎn)換為時(shí)間輪上的時(shí)間，通過與實(shí)際時(shí)間輪上的時(shí)間作比較，從而確定時(shí)間輪要前進(jìn)調(diào)度的時(shí)間，進(jìn)而操作對(duì)應(yīng)時(shí)間輪槽位對(duì)應(yīng)的任務(wù)==。

為什么至少需要這兩個(gè)成員呢？

定義多級(jí)時(shí)間輪，首先需要明確的便是級(jí)聯(lián)的層數(shù)，也就是說需要確定有幾個(gè)時(shí)間輪。
輪子上指針位置，就是當(dāng)前時(shí)間輪運(yùn)行到的位置，它與真實(shí)時(shí)間的差便是后續(xù)時(shí)間輪需要調(diào)度執(zhí)行，它們的差值是時(shí)間輪運(yùn)作起來的驅(qū)動(dòng)力。

多級(jí)時(shí)間輪對(duì)象的定義

//實(shí)現(xiàn)5級(jí)時(shí)間輪 范圍為0~ (2^8 * 2^6 * 2^6 * 2^6 *2^6)=2^32
struct tvec_base
{
    unsigned long 		current_index;   
    pthread_t  			thincrejiffies;
    pthread_t  			threadID;
    struct tvec_root 	tv1;	/*第一個(gè)輪*/
    struct tvec      	tv2;	/*第二個(gè)輪*/
    struct tvec      	tv3;	/*第三個(gè)輪*/
    struct tvec      	tv4;	/*第四個(gè)輪*/
    struct tvec      	tv5;	/*第五個(gè)輪*/
};

2.2 時(shí)間輪對(duì)象

我們知道每一個(gè)輪子實(shí)際上都是一個(gè)哈希表，上面我們只是實(shí)例化了五個(gè)輪子的對(duì)象，但是五個(gè)輪子具體包含什么，有幾個(gè)槽位等等沒有明確(即struct tvec和struct tvec_root)。

#define TVN_BITS 		6
#define TVR_BITS 		8
#define TVN_SIZE 		(1<<TVN_BITS)
#define TVR_SIZE 		(1<<TVR_BITS)

struct tvec {
    struct list_head vec[TVN_SIZE];/*64個(gè)格子*/
};
 
struct tvec_root{
    struct list_head vec[TVR_SIZE];/*256個(gè)格子*/
};

此外，每一個(gè)時(shí)間輪都是哈希表，因此它的類型應(yīng)該至少包含兩個(gè)指針域來實(shí)現(xiàn)雙向鏈表的功能。這里我們?yōu)榱朔奖闶褂猛ㄓ玫膕truct list_head的雙向鏈表結(jié)構(gòu)。

2.3 定時(shí)任務(wù)對(duì)象

定時(shí)器的主要工作是為了在未來的特定時(shí)間完成某項(xiàng)任務(wù)，而這個(gè)任務(wù)經(jīng)常包含以下內(nèi)容：

任務(wù)的處理邏輯(回調(diào)函數(shù))
任務(wù)的參數(shù)
雙向鏈表節(jié)點(diǎn)
到時(shí)時(shí)間

定時(shí)任務(wù)對(duì)象的定義

typedef void (*timeouthandle)(unsigned long );
 
struct timer_list{
    struct list_head entry;          //將時(shí)間連接成鏈表
    unsigned long expires;           //超時(shí)時(shí)間
    void (*function)(unsigned long); //超時(shí)后的處理函數(shù)
    unsigned long data;              //處理函數(shù)的參數(shù)
    struct tvec_base *base;          //指向時(shí)間輪
};

在時(shí)間輪上的效果圖：

2.4 雙向鏈表

在時(shí)間輪上我們采用雙向鏈表的數(shù)據(jù)類型。采用雙向鏈表的除了操作上比單鏈表復(fù)雜，多占一個(gè)指針域外沒有其他不可接收的問題。而多占一個(gè)指針域在今天大內(nèi)存的時(shí)代明顯不是什么問題。至于雙向鏈表操作的復(fù)雜性，我們可以通過使用通用的struct list結(jié)構(gòu)來解決，因?yàn)殡p向鏈表有眾多的標(biāo)準(zhǔn)操作函數(shù)，我們可以通過直接引用list.h頭文件來使用他們提供的接口。

struct list可以說是一個(gè)萬能的雙向鏈表操作框架，我們只需要在自定義的結(jié)構(gòu)中定義一個(gè)struct list對(duì)象即可使用它的標(biāo)準(zhǔn)操作接口。同時(shí)它還提供了一個(gè)類似container_of的接口，在應(yīng)用層一般叫做list_entry，因此我們可以很方便的通過struct list成員找到自定義的結(jié)構(gòu)體的起始地址。

關(guān)于應(yīng)用層的log.h, 我將在下面的代碼中附上該文件。如果需要內(nèi)核層的實(shí)現(xiàn)，可以直接從linux源碼中獲取。

2.5 聯(lián)結(jié)方式

多級(jí)時(shí)間輪效果圖：

3. 多級(jí)時(shí)間輪C語言實(shí)現(xiàn)

3.1 雙向鏈表頭文件: list.h

提到雙向鏈表，很多的源碼工程中都會(huì)實(shí)現(xiàn)一系列的統(tǒng)一的雙向鏈表操作函數(shù)。它們?yōu)殡p向鏈表封裝了統(tǒng)計(jì)的接口，使用者只需要在自定義的結(jié)構(gòu)中添加一個(gè)struct list_head結(jié)構(gòu)，然后調(diào)用它們提供的接口，便可以完成雙向鏈表的所有操作。這些操作一般都在list.h的頭文件中實(shí)現(xiàn)。Linux源碼中也有實(shí)現(xiàn)（內(nèi)核態(tài)的實(shí)現(xiàn)）。他們實(shí)現(xiàn)的方式基本完全一樣，只是實(shí)現(xiàn)的接口數(shù)量和功能上稍有差別?？梢哉f這個(gè)==list.h文件是學(xué)習(xí)操作雙向鏈表的不二選擇==，它幾乎實(shí)現(xiàn)了所有的操作：增、刪、改、查、遍歷、替換、清空等等。這里我拼湊了一個(gè)源碼中的log.h函數(shù)，終于湊夠了多級(jí)時(shí)間輪中使用到的接口(原來的博主沒有提供list.h文件，只能自己去東拼西湊)。

#if !defined(_BLKID_LIST_H) && !defined(LIST_HEAD)
#define _BLKID_LIST_H

#ifdef __cplusplus 
extern "C" {
#endif

/*
 * Simple doubly linked list implementation.
 *
 * Some of the internal functions ("__xxx") are useful when
 * manipulating whole lists rather than single entries, as
 * sometimes we already know the next/prev entries and we can
 * generate better code by using them directly rather than
 * using the generic single-entry routines.
 */

struct list_head {
	struct list_head *next, *prev;
};

#define LIST_HEAD_INIT(name) { &(name), &(name) }

#define LIST_HEAD(name) \
	struct list_head name = LIST_HEAD_INIT(name)

#define INIT_LIST_HEAD(ptr) do { \
	(ptr)->next = (ptr); (ptr)->prev = (ptr); \
} while (0)

static inline void
__list_add(struct list_head *entry,
                struct list_head *prev, struct list_head *next)
{
    next->prev = entry;
    entry->next = next;
    entry->prev = prev;
    prev->next = entry;
}

/**
 * Insert a new element after the given list head. The new element does not
 * need to be initialised as empty list.
 * The list changes from:
 *      head → some element → ...
 * to
 *      head → new element → older element → ...
 *
 * Example:
 * struct foo *newfoo = malloc(...);
 * list_add(&newfoo->entry, &bar->list_of_foos);
 *
 * @param entry The new element to prepend to the list.
 * @param head The existing list.
 */
static inline void
list_add(struct list_head *entry, struct list_head *head)
{
    __list_add(entry, head, head->next);
}

/**
 * Append a new element to the end of the list given with this list head.
 *
 * The list changes from:
 *      head → some element → ... → lastelement
 * to
 *      head → some element → ... → lastelement → new element
 *
 * Example:
 * struct foo *newfoo = malloc(...);
 * list_add_tail(&newfoo->entry, &bar->list_of_foos);
 *
 * @param entry The new element to prepend to the list.
 * @param head The existing list.
 */
static inline void
list_add_tail(struct list_head *entry, struct list_head *head)
{
    __list_add(entry, head->prev, head);
}

static inline void
__list_del(struct list_head *prev, struct list_head *next)
{
    next->prev = prev;
    prev->next = next;
}

/**
 * Remove the element from the list it is in. Using this function will reset
 * the pointers to/from this element so it is removed from the list. It does
 * NOT free the element itself or manipulate it otherwise.
 *
 * Using list_del on a pure list head (like in the example at the top of
 * this file) will NOT remove the first element from
 * the list but rather reset the list as empty list.
 *
 * Example:
 * list_del(&foo->entry);
 *
 * @param entry The element to remove.
 */
static inline void
list_del(struct list_head *entry)
{
    __list_del(entry->prev, entry->next);
}

static inline void
list_del_init(struct list_head *entry)
{
    __list_del(entry->prev, entry->next);
    INIT_LIST_HEAD(entry);
}

static inline void list_move_tail(struct list_head *list,
				  struct list_head *head)
{
	__list_del(list->prev, list->next);
	list_add_tail(list, head);
}

/**
 * Check if the list is empty.
 *
 * Example:
 * list_empty(&bar->list_of_foos);
 *
 * @return True if the list contains one or more elements or False otherwise.
 */
static inline int
list_empty(struct list_head *head)
{
    return head->next == head;
}


/**
 * list_replace - replace old entry by new one
 * @old : the element to be replaced
 * @new : the new element to insert
 *
 * If @old was empty, it will be overwritten.
 */
static inline void list_replace(struct list_head *old,
				struct list_head *new)
{
	new->next = old->next;
	new->next->prev = new;
	new->prev = old->prev;
	new->prev->next = new;
}

/**
 * Retrieve the first list entry for the given list pointer.
 *
 * Example:
 * struct foo *first;
 * first = list_first_entry(&bar->list_of_foos, struct foo, list_of_foos);
 *
 * @param ptr The list head
 * @param type Data type of the list element to retrieve
 * @param member Member name of the struct list_head field in the list element.
 * @return A pointer to the first list element.
 */
#define list_first_entry(ptr, type, member) \
    list_entry((ptr)->next, type, member)

static inline void list_replace_init(struct list_head *old,
					struct list_head *new)
{
	list_replace(old, new);
	INIT_LIST_HEAD(old);
}

/**
 * list_entry - get the struct for this entry
 * @ptr:	the &struct list_head pointer.
 * @type:	the type of the struct this is embedded in.
 * @member:	the name of the list_struct within the struct.
 */
#define list_entry(ptr, type, member) \
	((type *)((char *)(ptr)-(unsigned long)(&((type *)0)->member)))

/**
 * list_for_each - iterate over elements in a list
 * @pos:	the &struct list_head to use as a loop counter.
 * @head:	the head for your list.
 */
#define list_for_each(pos, head) \
	for (pos = (head)->next; pos != (head); pos = pos->next)

/**
 * list_for_each_safe - iterate over elements in a list, but don't dereference
 *                      pos after the body is done (in case it is freed)
 * @pos:	the &struct list_head to use as a loop counter.
 * @pnext:	the &struct list_head to use as a pointer to the next item.
 * @head:	the head for your list (not included in iteration).
 */
#define list_for_each_safe(pos, pnext, head) \
	for (pos = (head)->next, pnext = pos->next; pos != (head); \
	     pos = pnext, pnext = pos->next)

#ifdef __cplusplus
}
#endif

#endif /* _BLKID_LIST_H */

這里面一般會(huì)用到一個(gè)重要實(shí)現(xiàn)：==container_of==, 它的原理如果不清楚的話，可以閱讀另一篇專門介紹該函數(shù)的博文：container of()函數(shù)簡介

3.2 調(diào)試信息頭文件: log.h

這個(gè)頭文件實(shí)際上不是必須的，我只是用它來添加調(diào)試信息(代碼中的errlog(), log()都是log.h中的宏函數(shù))。它的效果是給打印的信息加上顏色，效果如下：

log.h的代碼如下：

#ifndef _LOG_h_
#define _LOG_h_
#include <stdio.h>

#define COL(x)  "\033[;" #x "m"
#define RED     COL(31)
#define GREEN   COL(32)
#define YELLOW  COL(33)
#define BLUE    COL(34)
#define MAGENTA COL(35)
#define CYAN    COL(36)
#define WHITE   COL(0)
#define GRAY    "\033[0m"

#define errlog(fmt, arg...) do{     \
    printf(RED"[#ERROR: Toeny Sun:"GRAY YELLOW" %s:%d]:"GRAY WHITE fmt GRAY, __func__, __LINE__, ##arg);\
}while(0)

#define log(fmt, arg...) do{     \
    printf(WHITE"[#DEBUG: Toeny Sun: "GRAY YELLOW"%s:%d]:"GRAY WHITE fmt GRAY, __func__, __LINE__, ##arg);\
}while(0)

#endif

3.3 時(shí)間輪代碼: timewheel.c

/*
 *毫秒定時(shí)器  采用多級(jí)時(shí)間輪方式  借鑒linux內(nèi)核中的實(shí)現(xiàn)
 *支持的范圍為1 ~  2^32 毫秒(大約有49天)
 *若設(shè)置的定時(shí)器超過最大值 則按最大值設(shè)置定時(shí)器
 **/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <pthread.h>
#include <sys/time.h>
#include "list.h"
#include "log.h" 

#define TVN_BITS 		6
#define TVR_BITS 		8
#define TVN_SIZE 		(1<<TVN_BITS)
#define TVR_SIZE 		(1<<TVR_BITS)
		
#define TVN_MASK 		(TVN_SIZE - 1)
#define TVR_MASK 		(TVR_SIZE - 1) 
 
#define SEC_VALUE 		0
#define USEC_VALUE 		2000
 
struct tvec_base;

#define INDEX(N) ((ba->current_index >> (TVR_BITS + (N) * TVN_BITS)) & TVN_MASK)
 
typedef void (*timeouthandle)(unsigned long );
 
 
struct timer_list{
    struct list_head entry;          //將時(shí)間連接成鏈表
    unsigned long expires;           //超時(shí)時(shí)間
    void (*function)(unsigned long); //超時(shí)后的處理函數(shù)
    unsigned long data;              //處理函數(shù)的參數(shù)
    struct tvec_base *base;          //指向時(shí)間輪
};
 
struct tvec {
    struct list_head vec[TVN_SIZE];
};
 
struct tvec_root{
    struct list_head vec[TVR_SIZE];
};
 
//實(shí)現(xiàn)5級(jí)時(shí)間輪 范圍為0~ (2^8 * 2^6 * 2^6 * 2^6 *2^6)=2^32
struct tvec_base
{
    unsigned long 		current_index;   
    pthread_t  			thincrejiffies;
    pthread_t  			threadID;
    struct tvec_root 	tv1;	/*第一個(gè)輪*/
    struct tvec      	tv2;	/*第二個(gè)輪*/
    struct tvec      	tv3;	/*第三個(gè)輪*/
    struct tvec      	tv4;	/*第四個(gè)輪*/
    struct tvec      	tv5;	/*第五個(gè)輪*/
};
 
static void internal_add_timer(struct tvec_base *base, struct timer_list *timer)
{
    struct list_head *vec;
    unsigned long expires = timer->expires;	
    unsigned long idx = expires - base->current_index;

#if 1 
    if( (signed long)idx < 0 ) /*這里是沒有辦法區(qū)分出是過時(shí)還是超長定時(shí)的吧?*/
    {
        vec = base->tv1.vec + (base->current_index & TVR_MASK);/*放到第一個(gè)輪的當(dāng)前槽*/
    }
	else if ( idx < TVR_SIZE ) /*第一個(gè)輪*/
    {
        int i = expires & TVR_MASK;
        vec = base->tv1.vec + i;
    }
    else if( idx < 1 << (TVR_BITS + TVN_BITS) )/*第二個(gè)輪*/
    {
        int i = (expires >> TVR_BITS) & TVN_MASK;
        vec = base->tv2.vec + i;
    }
    else if( idx < 1 << (TVR_BITS + 2 * TVN_BITS) )/*第三個(gè)輪*/
    {
        int i = (expires >> (TVR_BITS + TVN_BITS)) & TVN_MASK;
        vec = base->tv3.vec + i;
    }
    else if( idx < 1 << (TVR_BITS + 3 * TVN_BITS) )/*第四個(gè)輪*/
    {
        int i = (expires >> (TVR_BITS + 2 * TVN_BITS)) & TVN_MASK;
        vec = base->tv4.vec + i;
    }
    else											 /*第五個(gè)輪*/
    {
        int i;
        if (idx > 0xffffffffUL) 
        {
            idx = 0xffffffffUL;
            expires = idx + base->current_index;
        }
        i = (expires >> (TVR_BITS + 3 * TVN_BITS)) & TVN_MASK;
        vec = base->tv5.vec + i;
    }
#else
	/*上面可以優(yōu)化吧*/;
#endif 
    list_add_tail(&timer->entry, vec);
}
 
static inline void detach_timer(struct timer_list *timer)
{
    struct list_head *entry = &timer->entry;
    __list_del(entry->prev, entry->next);
    entry->next = NULL;
    entry->prev = NULL;
}
 
static int __mod_timer(struct timer_list *timer, unsigned long expires)
{        
    if(NULL != timer->entry.next)
        detach_timer(timer);
	
    internal_add_timer(timer->base, timer); 
 
    return 0;
}
 
//修改定時(shí)器的超時(shí)時(shí)間外部接口
int mod_timer(void *ptimer, unsigned long expires)
{
    struct timer_list *timer  = (struct timer_list *)ptimer;
    struct tvec_base *base;
	 
	base = timer->base;
    if(NULL == base)
        return -1;
    
    expires = expires + base->current_index; 	
    if(timer->entry.next != NULL  && timer->expires == expires)
        return 0;
 
    if( NULL == timer->function )
    {
        errlog("timer's timeout function is null\n");
        return -1;
    }
	
	timer->expires = expires;
    return __mod_timer(timer,expires);
}
 
//添加一個(gè)定時(shí)器
static void __ti_add_timer(struct timer_list *timer)
{
    if( NULL != timer->entry.next )
    {
        errlog("timer is already exist\n");
        return;
    }
 
    mod_timer(timer, timer->expires);            
}
 
/*添加一個(gè)定時(shí)器  外部接口
 *返回定時(shí)器
 */
void* ti_add_timer(void *ptimewheel, unsigned long expires,timeouthandle phandle, unsigned long arg)
{
    struct timer_list  *ptimer;
 
    ptimer = (struct timer_list *)malloc( sizeof(struct timer_list) );
    if(NULL == ptimer)
        return NULL;
 
    bzero( ptimer,sizeof(struct timer_list) );        
    ptimer->entry.next = NULL;
    ptimer->base = (struct tvec_base *)ptimewheel; 
    ptimer->expires = expires;
    ptimer->function  = phandle;
    ptimer->data = arg;
 
    __ti_add_timer(ptimer);
 
    return ptimer;
}
 
/*
 *刪除一個(gè)定時(shí)器  外部接口
 *
 * */
void ti_del_timer(void *p)
{
    struct timer_list *ptimer =(struct timer_list*)p;
 
    if(NULL == ptimer)
        return;
 
    if(NULL != ptimer->entry.next)
        detach_timer(ptimer);
    
    free(ptimer);
}
/*時(shí)間輪級(jí)聯(lián)*/ 
static int cascade(struct tvec_base *base, struct tvec *tv, int index)
{
    struct list_head *pos,*tmp;
    struct timer_list *timer;
    struct list_head tv_list;
    
	/*將tv[index]槽位上的所有任務(wù)轉(zhuǎn)移給tv_list,然后清空tv[index]*/
    list_replace_init(tv->vec + index, &tv_list);/*用tv_list替換tv->vec + index*/
 
    list_for_each_safe(pos, tmp, &tv_list)/*遍歷tv_list雙向鏈表，將任務(wù)重新添加到時(shí)間輪*/
    {
        timer = list_entry(pos,struct timer_list,entry);/*struct timer_list中成員entry的地址是pos, 獲取struct timer_list的首地址*/
        internal_add_timer(base, timer);
    }
 
    return index;
}
 
static void *deal_function_timeout(void *base)
{
    struct timer_list *timer;
    int ret;
    struct timeval tv;
    struct tvec_base *ba = (struct tvec_base *)base;
    
    for(;;)
    {
        gettimeofday(&tv, NULL);  
        while( ba->current_index <= (tv.tv_sec*1000 + tv.tv_usec/1000) )/*單位：ms*/
        {         
           struct list_head work_list;
           int index = ba->current_index & TVR_MASK;/*獲取第一個(gè)輪上的指針位置*/
           struct list_head *head = &work_list;
		   /*指針指向0槽時(shí)，級(jí)聯(lián)輪需要更新任務(wù)列表*/
           if(!index && (!cascade(ba, &ba->tv2, INDEX(0))) &&( !cascade(ba, &ba->tv3, INDEX(1))) && (!cascade(ba, &ba->tv4, INDEX(2))) )
               cascade(ba, &ba->tv5, INDEX(3));
           
            ba->current_index ++;
            list_replace_init(ba->tv1.vec + index, &work_list);
            while(!list_empty(head))
            {
                void (*fn)(unsigned long);
                unsigned long data;
                timer = list_first_entry(head, struct timer_list, entry);
                fn = timer->function;
                data = timer->data;
                detach_timer(timer);
                (*fn)(data);  
            }
        }
    }
}
 
static void init_tvr_list(struct tvec_root * tvr)
{
    int i;
 
    for( i = 0; i<TVR_SIZE; i++ )
        INIT_LIST_HEAD(&tvr->vec[i]);
}
 
 
static void init_tvn_list(struct tvec * tvn)
{
    int i;
 
    for( i = 0; i<TVN_SIZE; i++ )
        INIT_LIST_HEAD(&tvn->vec[i]);
}
 
//創(chuàng)建時(shí)間輪  外部接口
void *ti_timewheel_create(void )
{
    struct tvec_base *base;
    int ret = 0;
    struct timeval tv;
 
    base = (struct tvec_base *) malloc( sizeof(struct tvec_base) );
    if( NULL==base )
        return NULL;
    
    bzero( base,sizeof(struct tvec_base) );
        
    init_tvr_list(&base->tv1);
    init_tvn_list(&base->tv2);
    init_tvn_list(&base->tv3);
    init_tvn_list(&base->tv4);
    init_tvn_list(&base->tv5);
    
    gettimeofday(&tv, NULL);
    base->current_index = tv.tv_sec*1000 + tv.tv_usec/1000;/*當(dāng)前時(shí)間毫秒數(shù)*/
 
    if( 0 != pthread_create(&base->threadID,NULL,deal_function_timeout,base) )
    {
        free(base);
        return NULL;
    }    
    return base;
}
 
static void ti_release_tvr(struct tvec_root *pvr)
{
    int i;
    struct list_head *pos,*tmp;
    struct timer_list *pen;
 
    for(i = 0; i < TVR_SIZE; i++)
    {
        list_for_each_safe(pos,tmp,&pvr->vec[i])
        {
            pen = list_entry(pos,struct timer_list, entry);
            list_del(pos);
            free(pen);
        }
    }
}
 
static void ti_release_tvn(struct tvec *pvn)
{
    int i;
    struct list_head *pos,*tmp;
    struct timer_list *pen;
 
    for(i = 0; i < TVN_SIZE; i++)
    {
        list_for_each_safe(pos,tmp,&pvn->vec[i])
        {
            pen = list_entry(pos,struct timer_list, entry);
            list_del(pos);
            free(pen);
        }
    }
}
 
 
/*
 *釋放時(shí)間輪 外部接口
 * */
void ti_timewheel_release(void * pwheel)
{  
    struct tvec_base *base = (struct tvec_base *)pwheel;
    
    if(NULL == base)
        return;
 
    ti_release_tvr(&base->tv1);
    ti_release_tvn(&base->tv2);
    ti_release_tvn(&base->tv3);
    ti_release_tvn(&base->tv4);
    ti_release_tvn(&base->tv5);
 
    free(pwheel);
}
 
/************demo****************/
struct request_para{
    void *timer;
    int val;
};
 
void mytimer(unsigned long arg)
{
    struct request_para *para = (struct request_para *)arg;
 
    log("%d\n",para->val);
    mod_timer(para->timer,3000);  //進(jìn)行再次啟動(dòng)定時(shí)器
 
	sleep(10);/*定時(shí)器依然被阻塞*/
 
    //定時(shí)器資源的釋放是在這里完成的
    //ti_del_timer(para->timer);
}
 
int main(int argc,char *argv[])
{
    void *pwheel = NULL;
    void *timer  = NULL;
    struct request_para *para;
   
  
    para = (struct request_para *)malloc( sizeof(struct request_para) );
    if(NULL == para)
        return 0;
    bzero(para,sizeof(struct request_para));
 
    //創(chuàng)建一個(gè)時(shí)間輪
    pwheel = ti_timewheel_create();
    if(NULL == pwheel)
        return -1;
   
    //添加一個(gè)定時(shí)器
    para->val = 100;
    para->timer = ti_add_timer(pwheel, 3000, &mytimer, (unsigned long)para);
    
    while(1)
    {
        sleep(2);
    }
 
    //釋放時(shí)間輪
    ti_timewheel_release(pwheel);
    
    return 0;
}

3.4 編譯運(yùn)行

toney@ubantu:/mnt/hgfs/em嵌入式學(xué)習(xí)記錄/4. timerwheel/2. 多級(jí)時(shí)間輪$ ls
a.out  list.h  log.h  mutiTimeWheel.c
toney@ubantu:/mnt/hgfs/em嵌入式學(xué)習(xí)記錄/4. timerwheel/2. 多級(jí)時(shí)間輪$ gcc mutiTimeWheel.c -lpthread
toney@ubantu:/mnt/hgfs/em嵌入式學(xué)習(xí)記錄/4. timerwheel/2. 多級(jí)時(shí)間輪$ ./a.out 
[#DEBUG: Toeny Sun: mytimer:370]:100
[#DEBUG: Toeny Sun: mytimer:370]:100
[#DEBUG: Toeny Sun: mytimer:370]:100
[#DEBUG: Toeny Sun: mytimer:370]:100
[#DEBUG: Toeny Sun: mytimer:370]:100
[#DEBUG: Toeny Sun: mytimer:370]:100
[#DEBUG: Toeny Sun: mytimer:370]:100
[#DEBUG: Toeny Sun: mytimer:370]:100
[#DEBUG: Toeny Sun: mytimer:370]:100
[#DEBUG: Toeny Sun: mytimer:370]:100
[#DEBUG: Toeny Sun: mytimer:370]:100
[#DEBUG: Toeny Sun: mytimer:370]:100
[#DEBUG: Toeny Sun: mytimer:370]:100
[#DEBUG: Toeny Sun: mytimer:370]:100
[#DEBUG: Toeny Sun: mytimer:370]:100
[#DEBUG: Toeny Sun: mytimer:370]:100
[#DEBUG: Toeny Sun: mytimer:370]:100
[#DEBUG: Toeny Sun: mytimer:370]:100
[#DEBUG: Toeny Sun: mytimer:370]:100
[#DEBUG: Toeny Sun: mytimer:370]:100
[#DEBUG: Toeny Sun: mytimer:370]:100
[#DEBUG: Toeny Sun: mytimer:370]:100
[#DEBUG: Toeny Sun: mytimer:370]:100
[#DEBUG: Toeny Sun: mytimer:370]:100
[#DEBUG: Toeny Sun: mytimer:370]:100
[#DEBUG: Toeny Sun: mytimer:370]:100
[#DEBUG: Toeny Sun: mytimer:370]:100
[#DEBUG: Toeny Sun: mytimer:370]:100

從結(jié)果可以看出：如果添加的定時(shí)任務(wù)是比較耗時(shí)的操作，那么后續(xù)的任務(wù)也會(huì)被阻塞，可能一直到超時(shí)，甚至一直阻塞下去，這個(gè)取決于當(dāng)前任務(wù)是否耗時(shí)。這個(gè)理論上是絕不能接受的：一個(gè)任務(wù)不應(yīng)該也不能去影響其他的任務(wù)吧。但是目前沒有對(duì)此問題進(jìn)行改進(jìn)和完善，以后有機(jī)會(huì)再繼續(xù)完善吧。

總結(jié)

到此這篇關(guān)于利用C語言實(shí)現(xiàn)經(jīng)典多級(jí)時(shí)間輪定時(shí)器的文章就介紹到這了,更多相關(guān)C語言多級(jí)時(shí)間輪定時(shí)器內(nèi)容請搜索腳本之家以前的文章或繼續(xù)瀏覽下面的相關(guān)文章希望大家以后多多支持腳本之家！

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