AMPS:数据库访问模块源码解读

  AMPS做为一个中间件，也提供了访问数据库的接口，目前支持MySQL和Oracle（对我所喜爱PostgreSQL却默认不支持，看来我的爱好属于非主流哈~），下面要看的是DBEngine库，它只做一件事情，就是封装了不同数据库操作的差异，提供一个数据库统一访问接口。下节再看针对不同数据库的具体操作。

AMPS_DBEngine.h

#ifndef __HEADER_AMPS_DB_ENGINE_H
#define __HEADER_AMPS_DB_ENGINE_H

#ifdef __cplusplus
extern "C" {
#endif

#include "AMPS_Defines.h"
#include "AMPS_LinkList.h"
#include "AMPS_MemMgt.h"
#include "AMPS_EventSystem.h"
#include "AMPS_Core.h"
#include "AMPS_API.h"

typedef struct _BDEngineContext					t_BDEngineContext;

struct _BDEngineContext
{
	void*					poDBHandle;
	void*					pvAMPSContext;			//pointer to framework context
	e_AMPSDBType			oAMPSDBType;

	char					pchHostName[AMPS_MAX_IP_STRING_LENGTH];
	char					pchUserName[AMPS_SIZE_OF_DB_USER_NAME];
	char 					pchPassword[AMPS_SIZE_OF_DB_PWD];
	char					pchDataBaseName[AMPS_SIZE_OF_DB_NAME];
	unsigned int 			unDBPort;
	char					pchUnixSocket[AMPS_SIZE_OF_DB_UNIX_SOCKET];
	unsigned long 			ulClientFlag;
};

void* DBEngine_Init(void* r_pvAMPSContext, e_AMPSDBType r_oAMPSDBType, char* r_pchHostName, char* r_pchUserName, char* r_pchPassword, char* r_pchDataBaseName);
void DBEngine_Cleanup(void* r_pvAMPSContext, void* r_pvBDEngineContext);
int DBEngine_Query(void* r_pvAMPSContext, void* r_pvBDEngineContext, const char* r_pcchQueryStatement, unsigned long r_ulLengthOfQuery, t_AMPSDBEngineResult* r_poAMPSDBEngineResult);
void DBEngine_FreeResults(void* r_pvAMPSContext, void* r_pvBDEngineContext, t_AMPSDBEngineResult* r_poAMPSDBEngineResult);

#ifdef __cplusplus
}
#endif

#endif //__HEADER_AMPS_DB_ENGINE_H

AMPS_DBEngine.c

#include "AMPS_DBEngine.h"
#include "AMPS_MySQL.h"
#include "AMPS_Oracle.h"

/*****************************************************************
函数名称: DBEngine_Init
功能描述: 数据库访问初始化函数
入参::
      void* r_pvAMPSContext APMS应用上下文
      e_AMPSDBType r_oAMPSDBType 数据库类型(MySQL或Oracle)
      char* r_pchHostName 数据库的监听IP
      char* r_pchUserName 数据库访问用户名
      char* r_pchPassword 数据库访问密码
      char* r_pchDataBaseName 数据库名称
      
出参:
      
返回值:
      void* 数据库访问句柄

*****************************************************************/
void* DBEngine_Init(void* r_pvAMPSContext, e_AMPSDBType r_oAMPSDBType, char* r_pchHostName, char* r_pchUserName, char* r_pchPassword, char* r_pchDataBaseName)
{
	t_BDEngineContext* poBDEngineContext = NULL;

	//TRACE( DBE_TRACE_ID(r_pvAMPSContext), AMPS_TRACE_LEVEL_INFO, "Entering.\n");
	
	poBDEngineContext = (t_BDEngineContext*)AMPS_InternalMalloc(sizeof(t_BDEngineContext));
	if(NULL == poBDEngineContext)
	{
		TRACE( DBE_TRACE_ID(r_pvAMPSContext), AMPS_TRACE_LEVEL_ERROR, "AMPS_InternalMalloc failed for poBDEngineContext.\n");
    	return NULL;
  	}

	poBDEngineContext->pvAMPSContext = r_pvAMPSContext;
	poBDEngineContext->oAMPSDBType = r_oAMPSDBType;

	memcpy(poBDEngineContext->pchHostName, r_pchHostName, strlen(r_pchHostName));
	//TRACE( DBE_TRACE_ID(r_pvAMPSContext), AMPS_TRACE_LEVEL_DEBUG, "Host Name is %s.\n", poBDEngineContext->pchHostName);
	memcpy(poBDEngineContext->pchUserName, r_pchUserName, strlen(r_pchUserName));
	//TRACE( DBE_TRACE_ID(r_pvAMPSContext), AMPS_TRACE_LEVEL_DEBUG, "User Name is %s.\n", poBDEngineContext->pchUserName);
	memcpy(poBDEngineContext->pchPassword, r_pchPassword, strlen(r_pchPassword));
	//TRACE( DBE_TRACE_ID(r_pvAMPSContext), AMPS_TRACE_LEVEL_DEBUG, "Password is %s.\n", poBDEngineContext->pchPassword);
	memcpy(poBDEngineContext->pchDataBaseName, r_pchDataBaseName, strlen(r_pchDataBaseName));
	//TRACE( DBE_TRACE_ID(r_pvAMPSContext), AMPS_TRACE_LEVEL_DEBUG, "DataBase Name is %s.\n", poBDEngineContext->pchDataBaseName);

    /*根据不同的数据库类型，进行访问前的初始化*/
	if(AMPS_DB_TYPE_MYSQL == poBDEngineContext->oAMPSDBType)
	{
		if(AMPS_SUCCESS != MySQL_Init(r_pvAMPSContext, poBDEngineContext))
		{
			TRACE(DBE_TRACE_ID(r_pvAMPSContext), AMPS_TRACE_LEVEL_ERROR, "MySQL_Init failed.\n");
			return NULL;
		}
	}
	else
	if(AMPS_DB_TYPE_ORACLE == poBDEngineContext->oAMPSDBType)
	{
		if(AMPS_SUCCESS != Oracle_Init(r_pvAMPSContext, poBDEngineContext))
		{
			TRACE(DBE_TRACE_ID(r_pvAMPSContext), AMPS_TRACE_LEVEL_ERROR, "Oracle_Init failed.\n");
			return NULL;
		}
	}
	else
	{
		TRACE(DBE_TRACE_ID(r_pvAMPSContext), AMPS_TRACE_LEVEL_ERROR, "Invalid DB Type %d.\n", r_oAMPSDBType);
		return NULL;
	}

	//TRACE( DBE_TRACE_ID(r_pvAMPSContext), AMPS_TRACE_LEVEL_INFO, "Leaving.\n");
	return poBDEngineContext;
}

/*****************************************************************
函数名称: DBEngine_Cleanup
功能描述: 数据库访问完成后的资源销毁函数
入参::
      void* r_pvAMPSContext APMS应用上下文
      void* r_pvBDEngineContext 数据库访问句柄

      
出参:
      
返回值:
      void

*****************************************************************/
void DBEngine_Cleanup(void* r_pvAMPSContext, void* r_pvBDEngineContext)
{
	t_BDEngineContext* poBDEngineContext = r_pvBDEngineContext;

	//TRACE( DBE_TRACE_ID(r_pvAMPSContext), AMPS_TRACE_LEVEL_INFO, "Entering.\n");

    /*根据不同数据库类型进行数据库关闭等清理操作*/
	if(AMPS_DB_TYPE_MYSQL == poBDEngineContext->oAMPSDBType)
	{
		MySQL_Cleanup(r_pvAMPSContext, poBDEngineContext);
	}
	else
	if(AMPS_DB_TYPE_ORACLE == poBDEngineContext->oAMPSDBType)
	{
		Oracle_Cleanup(r_pvAMPSContext, poBDEngineContext);
	}
	
	AMPS_InternalFree(r_pvBDEngineContext);
	//TRACE( DBE_TRACE_ID(r_pvAMPSContext), AMPS_TRACE_LEVEL_INFO, "Leaving.\n");
}

/*****************************************************************
函数名称: DBEngine_Query
功能描述: 数据库操作语句执行函数
入参::
      void* r_pvAMPSContext APMS应用上下文
      void* r_pvBDEngineContext 数据库访问句柄
      char* r_pcchQueryStatement 需要执行的SQL语句
      unsigned long r_ulLengthOfQuery SQL语句长度
      t_AMPSDBEngineResult* r_poBDEngineResult 查询完成后的结果集
      
出参:
      t_AMPSDBEngineResult* r_poBDEngineResult 查询完成后的结果集
      
返回值:
      int

*****************************************************************/
int DBEngine_Query(void* r_pvAMPSContext, void* r_pvBDEngineContext, const char* r_pcchQueryStatement, unsigned long r_ulLengthOfQuery, t_AMPSDBEngineResult* r_poBDEngineResult)
{
	t_BDEngineContext* poBDEngineContext = r_pvBDEngineContext;

	//TRACE( DBE_TRACE_ID(r_pvAMPSContext), AMPS_TRACE_LEVEL_INFO, "Entering.\n");

    /*按不同数据库类型进行SQL语句的执行*/
	if(AMPS_DB_TYPE_MYSQL == poBDEngineContext->oAMPSDBType)
	{
		MySQL_Query(r_pvAMPSContext, r_pvBDEngineContext, r_pcchQueryStatement, r_ulLengthOfQuery, r_poBDEngineResult);
	}
	else
	if(AMPS_DB_TYPE_ORACLE == poBDEngineContext->oAMPSDBType)
	{
		Oracle_Query(r_pvAMPSContext, r_pvBDEngineContext, r_pcchQueryStatement, r_ulLengthOfQuery, r_poBDEngineResult);
	}

	//TRACE( DBE_TRACE_ID(r_pvAMPSContext), AMPS_TRACE_LEVEL_INFO, "Leaving.\n");
	return AMPS_SUCCESS;
}

/*****************************************************************
函数名称: DBEngine_FreeResults
功能描述: 数据库操作语句执行完成后的资源释放函数
入参::
      void* r_pvAMPSContext APMS应用上下文
      void* r_pvBDEngineContext 数据库访问句柄
      t_AMPSDBEngineResult* r_poBDEngineResult 查询完成后的结果集
      
出参:
      
返回值:
      int

*****************************************************************/
void DBEngine_FreeResults(void* r_pvAMPSContext, void* r_pvBDEngineContext, t_AMPSDBEngineResult* r_poBDEngineResult)
{
	t_BDEngineContext* poBDEngineContext = r_pvBDEngineContext;

	//TRACE( DBE_TRACE_ID(r_pvAMPSContext), AMPS_TRACE_LEVEL_INFO, "Entering.\n");

    /*按不同数据库类型进行SQL语句的执行后的资源释放*/

	if(AMPS_DB_TYPE_MYSQL == poBDEngineContext->oAMPSDBType)
	{
		MySQL_FreeResults(r_pvAMPSContext, r_pvBDEngineContext, r_poBDEngineResult);
	}
	else
	if(AMPS_DB_TYPE_ORACLE == poBDEngineContext->oAMPSDBType)
	{
		Oracle_FreeResults(r_pvAMPSContext, r_pvBDEngineContext, r_poBDEngineResult);
	}

	//TRACE( DBE_TRACE_ID(r_pvAMPSContext), AMPS_TRACE_LEVEL_INFO, "Leaving.\n");
}