sema.mx

一个内存数据库的源代码这是服务器端还有客户端

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@' Version 1.1 (the "License"); you may not use this file except in
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@' License for the specific language governing rights and limitations
@' under the License.
@'
@' The Original Code is the MonetDB Database System.
@'
@' The Initial Developer of the Original Code is CWI.
@' Portions created by CWI are Copyright (C) 1997-2007 CWI.
@' All Rights Reserved.

@f sema
@a Peter Boncz
@v 1.0
@-
This module provides simple SMP lock and thread functionality
as already present in the MonetDB system.
@{
@+ semaphores
@mal
atom sema:ptr;

command create(init:int ) :sema 
address SEMAcreate
comment "Create an unset sema, with an initial value";
command down(s:sema) 
address SEMAdown
comment "Decrement the semaphpore if >0; else block";
command up(s:sema) 
address SEMAup
comment "Increment the semaphore";
command destroy(s:sema) 
address SEMAdestroy
comment "Destroy a semaphore";
@+ Implementation
@c
#include "mal_config.h"
#include <gdk.h>
#include "mal_exception.h"
typedef ptr sema;
typedef ptr monet_sema;

#ifdef WIN32
#ifndef LIBSEMA
#define sema_export extern __declspec(dllimport)
#else
#define sema_export extern __declspec(dllexport)
#endif
#else
#define sema_export extern
#endif

int
create_sema(monet_sema *s, int *init)
{
	*s = (monet_sema) GDKmalloc(sizeof(MT_Sema));
	if (*s == NULL || *s == ptr_nil) return GDK_FAIL;
	MT_sema_init((MT_Sema *) *s, *init);
	return GDK_SUCCEED;
}

int
up_sema(monet_sema *s)
{
	if (*s == NULL || *s == ptr_nil) return GDK_FAIL;
	MT_sema_up((MT_Sema*) *s, "up_sema");
	return GDK_SUCCEED;
}

int
down_sema(monet_sema *s)
{
    if (*s == NULL || *s == ptr_nil) return GDK_FAIL;
    MT_sema_down((MT_Sema*) *s, "down_sema");
	return GDK_SUCCEED;
}

int
destroy_sema(monet_sema *s)
{
	if (*s == NULL || *s == ptr_nil) return GDK_FAIL;
	MT_sema_destroy((MT_Sema*) *s);
	GDKfree(*s);
	return GDK_SUCCEED;
}

@-
The old code base is wrapped to ease update propagation.
@c
#include "mal.h"
sema_export str SEMAcreate(monet_sema *res, int *init);
str
SEMAcreate(monet_sema *res, int *init)
{
	create_sema(res, init);
	return MAL_SUCCEED;
}

sema_export str SEMAup(int *res, monet_sema *s);
str
SEMAup(int *res, monet_sema *s)
{
	up_sema(s);
	*res = 1;
	return MAL_SUCCEED;
}

sema_export str SEMAdown(int *res, monet_sema *s);
str
SEMAdown(int *res, monet_sema *s)
{
	down_sema(s);
	*res = 1;
	return MAL_SUCCEED;
}

sema_export str SEMAdestroy(int *res, monet_sema *s);
str
SEMAdestroy(int *res, monet_sema *s)
{
	destroy_sema(s);
	*res = 1;
	return MAL_SUCCEED;
}

@}