此示例说明了 NDB API 中同步事务的使用。它首先使用带有 SQL 节点的 MySQL C API 创建一个数据库
ndb_examples
和一个表
api_simple
(如果这些对象尚不存在),然后使用新开发银行 API。
编译后的程序有两个参数:
NDB Cluster 连接字符串(请参阅 NDB Cluster 连接字符串)
该程序的正确输出如下:
ATTR1 ATTR2
0 10
1 1
2 12
Detected that deleted tuple doesn't exist!
4 14
5 5
6 16
7 7
8 18
9 9
此示例的源代码可以
storage/ndb/ndbapi-examples/ndbapi_simple/ndbapi_simple.cpp
在 NDB Cluster 源代码树中找到,并在此处复制:
/*
* ndbapi_simple.cpp: Using synchronous transactions in NDB API
*
* Correct output from this program is:
*
* ATTR1 ATTR2
* 0 10
* 1 1
* 2 12
* Detected that deleted tuple doesn't exist!
* 4 14
* 5 5
* 6 16
* 7 7
* 8 18
* 9 9
*
*/
#include <mysql.h>
#include <mysqld_error.h>
#include <NdbApi.hpp>
// Used for cout
#include <stdio.h>
#include <iostream>
static void run_application(MYSQL &, Ndb_cluster_connection &);
#define PRINT_ERROR(code,msg) \
std::cout << "Error in " << __FILE__ << ", line: " << __LINE__ \
<< ", code: " << code \
<< ", msg: " << msg << "." << std::endl
#define MYSQLERROR(mysql) { \
PRINT_ERROR(mysql_errno(&mysql),mysql_error(&mysql)); \
exit(-1); }
#define APIERROR(error) { \
PRINT_ERROR(error.code,error.message); \
exit(-1); }
int main(int argc, char** argv)
{
if (argc != 3)
{
std::cout << "Arguments are <socket mysqld> <connect_string cluster>.\n";
exit(-1);
}
// ndb_init must be called first
ndb_init();
// connect to mysql server and cluster and run application
{
char * mysqld_sock = argv[1];
const char *connection_string = argv[2];
// Object representing the cluster
Ndb_cluster_connection cluster_connection(connection_string);
// Connect to cluster management server (ndb_mgmd)
if (cluster_connection.connect(4 /* retries */,
5 /* delay between retries */,
1 /* verbose */))
{
std::cout << "Cluster management server was not ready within 30 secs.\n";
exit(-1);
}
// Optionally connect and wait for the storage nodes (ndbd's)
if (cluster_connection.wait_until_ready(30,0) < 0)
{
std::cout << "Cluster was not ready within 30 secs.\n";
exit(-1);
}
// connect to mysql server
MYSQL mysql;
if ( !mysql_init(&mysql) ) {
std::cout << "mysql_init failed\n";
exit(-1);
}
if ( !mysql_real_connect(&mysql, "localhost", "root", "", "",
0, mysqld_sock, 0) )
MYSQLERROR(mysql);
// run the application code
run_application(mysql, cluster_connection);
mysql_close(&mysql);
}
ndb_end(0);
return 0;
}
static void create_table(MYSQL &);
static void do_insert(Ndb &);
static void do_update(Ndb &);
static void do_delete(Ndb &);
static void do_read(Ndb &);
static void run_application(MYSQL &mysql,
Ndb_cluster_connection &cluster_connection)
{
/********************************************
* Connect to database via mysql-c *ndb_examples
********************************************/
mysql_query(&mysql, "CREATE DATABASE ndb_examples");
if (mysql_query(&mysql, "USE ndb_examples") != 0) MYSQLERROR(mysql);
create_table(mysql);
/********************************************
* Connect to database via NDB API *
********************************************/
// Object representing the database
Ndb myNdb( &cluster_connection, "ndb_examples" );
if (myNdb.init()) APIERROR(myNdb.getNdbError());
/*
* Do different operations on database
*/
do_insert(myNdb);
do_update(myNdb);
do_delete(myNdb);
do_read(myNdb);
}
/*********************************************************
* Create a table named api_simple if it does not exist *
*********************************************************/
static void create_table(MYSQL &mysql)
{
while (mysql_query(&mysql,
"CREATE TABLE"
" api_simple"
" (ATTR1 INT UNSIGNED NOT NULL PRIMARY KEY,"
" ATTR2 INT UNSIGNED NOT NULL)"
" ENGINE=NDB"))
{
if (mysql_errno(&mysql) == ER_TABLE_EXISTS_ERROR)
{
std::cout << "NDB Cluster already has example table: api_simple. "
<< "Dropping it..." << std::endl;
mysql_query(&mysql, "DROP TABLE api_simple");
}
else MYSQLERROR(mysql);
}
}
/**************************************************************************
* Using 5 transactions, insert 10 tuples in table: (0,0),(1,1),...,(9,9) *
**************************************************************************/
static void do_insert(Ndb &myNdb)
{
const NdbDictionary::Dictionary* myDict= myNdb.getDictionary();
const NdbDictionary::Table *myTable= myDict->getTable("api_simple");
if (myTable == NULL)
APIERROR(myDict->getNdbError());
for (int i = 0; i < 5; i++) {
NdbTransaction *myTransaction= myNdb.startTransaction();
if (myTransaction == NULL) APIERROR(myNdb.getNdbError());
NdbOperation *myOperation= myTransaction->getNdbOperation(myTable);
if (myOperation == NULL) APIERROR(myTransaction->getNdbError());
myOperation->insertTuple();
myOperation->equal("ATTR1", i);
myOperation->setValue("ATTR2", i);
myOperation= myTransaction->getNdbOperation(myTable);
if (myOperation == NULL) APIERROR(myTransaction->getNdbError());
myOperation->insertTuple();
myOperation->equal("ATTR1", i+5);
myOperation->setValue("ATTR2", i+5);
if (myTransaction->execute( NdbTransaction::Commit ) == -1)
APIERROR(myTransaction->getNdbError());
myNdb.closeTransaction(myTransaction);
}
}
/*****************************************************************
* Update the second attribute in half of the tuples (adding 10) *
*****************************************************************/
static void do_update(Ndb &myNdb)
{
const NdbDictionary::Dictionary* myDict= myNdb.getDictionary();
const NdbDictionary::Table *myTable= myDict->getTable("api_simple");
if (myTable == NULL)
APIERROR(myDict->getNdbError());
for (int i = 0; i < 10; i+=2) {
NdbTransaction *myTransaction= myNdb.startTransaction();
if (myTransaction == NULL) APIERROR(myNdb.getNdbError());
NdbOperation *myOperation= myTransaction->getNdbOperation(myTable);
if (myOperation == NULL) APIERROR(myTransaction->getNdbError());
myOperation->updateTuple();
myOperation->equal( "ATTR1", i );
myOperation->setValue( "ATTR2", i+10);
if( myTransaction->execute( NdbTransaction::Commit ) == -1 )
APIERROR(myTransaction->getNdbError());
myNdb.closeTransaction(myTransaction);
}
}
/*************************************************
* Delete one tuple (the one with primary key 3) *
*************************************************/
static void do_delete(Ndb &myNdb)
{
const NdbDictionary::Dictionary* myDict= myNdb.getDictionary();
const NdbDictionary::Table *myTable= myDict->getTable("api_simple");
if (myTable == NULL)
APIERROR(myDict->getNdbError());
NdbTransaction *myTransaction= myNdb.startTransaction();
if (myTransaction == NULL) APIERROR(myNdb.getNdbError());
NdbOperation *myOperation= myTransaction->getNdbOperation(myTable);
if (myOperation == NULL) APIERROR(myTransaction->getNdbError());
myOperation->deleteTuple();
myOperation->equal( "ATTR1", 3 );
if (myTransaction->execute(NdbTransaction::Commit) == -1)
APIERROR(myTransaction->getNdbError());
myNdb.closeTransaction(myTransaction);
}
/*****************************
* Read and print all tuples *
*****************************/
static void do_read(Ndb &myNdb)
{
const NdbDictionary::Dictionary* myDict= myNdb.getDictionary();
const NdbDictionary::Table *myTable= myDict->getTable("api_simple");
if (myTable == NULL)
APIERROR(myDict->getNdbError());
std::cout << "ATTR1 ATTR2" << std::endl;
for (int i = 0; i < 10; i++) {
NdbTransaction *myTransaction= myNdb.startTransaction();
if (myTransaction == NULL) APIERROR(myNdb.getNdbError());
NdbOperation *myOperation= myTransaction->getNdbOperation(myTable);
if (myOperation == NULL) APIERROR(myTransaction->getNdbError());
myOperation->readTuple(NdbOperation::LM_Read);
myOperation->equal("ATTR1", i);
NdbRecAttr *myRecAttr= myOperation->getValue("ATTR2", NULL);
if (myRecAttr == NULL) APIERROR(myTransaction->getNdbError());
if(myTransaction->execute( NdbTransaction::Commit ) == -1)
APIERROR(myTransaction->getNdbError());
if (myTransaction->getNdbError().classification == NdbError::NoDataFound)
if (i == 3)
std::cout << "Detected that deleted tuple doesn't exist!" << std::endl;
else
APIERROR(myTransaction->getNdbError());
if (i != 3) {
printf(" %2d %2d\n", i, myRecAttr->u_32_value());
}
myNdb.closeTransaction(myTransaction);
}
}