cutil-slock.c

来自「Linux环境下常用功能的实现」· C语言 代码 · 共 143 行

#include "cutil.h"

/**
 * cutil_slock_init
 * @nKey: 信号锁的键值
 *
 * 创建并初始化信号锁
 * 
 * Returns: 成功返回信号锁键值.失败返回-1
 */
int cutil_slock_init(int nKey)
{
	int nSemId;
	union semun {
		int val;
	}arg;

	if((nSemId = semget(nKey, 3, IPC_CREAT | IPC_EXCL| 0600)) < 0)
	{
		if(errno == EEXIST)
		{
			if((nSemId = semget(nKey, 3, 0600)) < 0)
			{
				cutil_log_error(N_("create semphore:%d error:%s\n"), 
					nKey, strerror(errno));
				return -1;
			}
			return nSemId;
		}
	}
	arg.val = 0;
	if(semctl(nSemId, 0, SETVAL, arg) < 0)
	{
		cutil_log_error(N_("set semphore value error:%s\n"), strerror(errno));
		return -1;
	}
	arg.val = 0;
	if(semctl(nSemId, 1, SETVAL, arg) < 0)
	{
		cutil_log_error(N_("set semphore value error:%s\n"), strerror(errno));
		return -1;
	}
	arg.val = 1;
	if(semctl(nSemId, 2, SETVAL, arg) < 0)
	{
		cutil_log_error(N_("set semphore value error:%s\n"), strerror(errno));
		return -1;
	}
	return nSemId;
}

/**
 * cutil_slock_set_read
 * @nSemID: 信号锁的键值
 *
 * 设置只读锁
 * 
 * Returns: 成功返回0.失败返回-1
 */
int cutil_slock_set_read(int nSemID)
{
	static struct sembuf struSemBuf[2] = {
		{0, 1, 0},
		{1, 0, 0},
	};

	if(semop(nSemID, struSemBuf, 2) < 0)
	{
		cutil_log_error(N_("set read lock error:%s\n"), strerror(errno));
		return -1;
	}
	return 0;
}

/**
 * cutil_slock_unset_read
 * @nSemID: 信号锁的键值
 *
 * 取消只读锁
 * 
 * Returns: 成功返回0.失败返回-1
 */
int cutil_slock_unset_read(int nSemId)
{
	static struct sembuf struSemBuf[1] = {
		{0, -1, IPC_NOWAIT},
	};

	if(semop(nSemId, struSemBuf, 1) < 0)
	{
		cutil_log_error(N_("unset read lock error:%s\n"), strerror(errno));
		return -1;
	}
	return 0;
}

/**
 * cutil_slock_set_write
 * @nSemID: 信号锁的键值
 *
 * 设置只写锁
 * 
 * Returns: 成功返回0.失败返回-1
 */
int cutil_slock_set_write(int nSemID)
{
	static struct sembuf struSemBuf[3] = {
		{0, 0, 0},
		{1, 1, 0},
		{2, -1, 0},
	};

	if(semop(nSemID, struSemBuf, 3) < 0)
	{
		cutil_log_error(N_("set write lock error:%s\n"), strerror(errno));
		return -1;
	}
	return 0;
}

/**
 * cutil_slock_unset_write
 * @nSemID: 信号锁的键值
 *
 * 取消只写锁
 * 
 * Returns: 成功返回0.失败返回-1
 */
int cutil_slock_unset_write(int nSemId)
{
	static struct sembuf struSemBuf[2] = {
		{1, -1, IPC_NOWAIT},
		{2, 1, IPC_NOWAIT}
	};

	if(semop(nSemId, struSemBuf, 2) < 0)
	{
		cutil_log_error(N_("unset write lock error:%s\n"), strerror(errno));
		return -1;
	}
	return 0;
}