此示例演示同步事务并连接到单个 NDB API 应用程序中的多个集群。
该程序的源代码可以在 NDB Cluster 源代码树中的
storage/ndb/ndbapi-examples/ndbapi_simple_dual/main.cpp.
笔记
示例文件以前名为
ndbapi_simple_dual.cpp.
/*
* ndbapi_simple_dual: 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
* 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
*
*/
#ifdef _WIN32
#include <winsock2.h>
#endif
#include <mysql.h>
#include <NdbApi.hpp>
#include <stdlib.h>
// Used for cout
#include <stdio.h>
#include <iostream>
static void run_application(MYSQL &, Ndb_cluster_connection &, const char* table, const char* db);
#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 != 5)
{
std::cout << "Arguments are <socket mysqld1> <connect_string cluster 1> <socket mysqld2> <connect_string cluster 2>.\n";
exit(-1);
}
// ndb_init must be called first
ndb_init();
{
char * mysqld1_sock = argv[1];
const char *connectstring1 = argv[2];
char * mysqld2_sock = argv[3];
const char *connectstring2 = argv[4];
// Object representing the cluster 1
Ndb_cluster_connection cluster1_connection(connectstring1);
MYSQL mysql1;
// Object representing the cluster 2
Ndb_cluster_connection cluster2_connection(connectstring2);
MYSQL mysql2;
// connect to mysql server and cluster 1 and run application
// Connect to cluster 1 management server (ndb_mgmd)
if (cluster1_connection.connect(4 /* retries */,
5 /* delay between retries */,
1 /* verbose */))
{
std::cout << "Cluster 1 management server was not ready within 30 secs.\n";
exit(-1);
}
// Optionally connect and wait for the storage nodes (ndbd's)
if (cluster1_connection.wait_until_ready(30,0) < 0)
{
std::cout << "Cluster 1 was not ready within 30 secs.\n";
exit(-1);
}
// connect to mysql server in cluster 1
if ( !mysql_init(&mysql1) ) {
std::cout << "mysql_init failed\n";
exit(-1);
}
if ( !mysql_real_connect(&mysql1, "localhost", "root", "", "",
0, mysqld1_sock, 0) )
MYSQLERROR(mysql1);
// connect to mysql server and cluster 2 and run application
// Connect to cluster management server (ndb_mgmd)
if (cluster2_connection.connect(4 /* retries */,
5 /* delay between retries */,
1 /* verbose */))
{
std::cout << "Cluster 2 management server was not ready within 30 secs.\n";
exit(-1);
}
// Optionally connect and wait for the storage nodes (ndbd's)
if (cluster2_connection.wait_until_ready(30,0) < 0)
{
std::cout << "Cluster 2 was not ready within 30 secs.\n";
exit(-1);
}
// connect to mysql server in cluster 2
if ( !mysql_init(&mysql2) ) {
std::cout << "mysql_init failed\n";
exit(-1);
}
if ( !mysql_real_connect(&mysql2, "localhost", "root", "", "",
0, mysqld2_sock, 0) )
MYSQLERROR(mysql2);
// run the application code
run_application(mysql1, cluster1_connection, "api_simple_dual_1", "ndb_examples");
run_application(mysql2, cluster2_connection, "api_simple_dual_2", "ndb_examples");
}
// Note: all connections must have been destroyed before calling ndb_end()
ndb_end(0);
return 0;
}
static void create_table(MYSQL &, const char* table);
static void do_insert(Ndb &, const char* table);
static void do_update(Ndb &, const char* table);
static void do_delete(Ndb &, const char* table);
static void do_read(Ndb &, const char* table);
static void drop_table(MYSQL &,const char* table);
static void run_application(MYSQL &mysql,
Ndb_cluster_connection &cluster_connection,
const char* table,
const char* db)
{
/********************************************
* Connect to database via mysql-c *
********************************************/
char db_stmt[256];
sprintf(db_stmt, "CREATE DATABASE %s\n", db);
mysql_query(&mysql, db_stmt);
sprintf(db_stmt, "USE %s", db);
if (mysql_query(&mysql, db_stmt) != 0) MYSQLERROR(mysql);
create_table(mysql, table);
/********************************************
* Connect to database via NdbApi *
********************************************/
// Object representing the database
Ndb myNdb( &cluster_connection, db );
if (myNdb.init()) APIERROR(myNdb.getNdbError());
/*
* Do different operations on database
*/
do_insert(myNdb, table);
do_update(myNdb, table);
do_delete(myNdb, table);
do_read(myNdb, table);
/*
* Drop the table
*/
drop_table(mysql,table);
}
/*********************************************************
* Create a table named by table if it does not exist *
*********************************************************/
static void create_table(MYSQL &mysql, const char* table)
{
char create_stmt[256];
sprintf(create_stmt, "CREATE TABLE %s \
(ATTR1 INT UNSIGNED NOT NULL PRIMARY KEY,\
ATTR2 INT UNSIGNED NOT NULL)\
ENGINE=NDB", table);
if (mysql_query(&mysql, create_stmt))
MYSQLERROR(mysql);
}
/**************************************************************************
* Using 5 transactions, insert 10 tuples in table: (0,0),(1,1),...,(9,9) *
**************************************************************************/
static void do_insert(Ndb &myNdb, const char* table)
{
const NdbDictionary::Dictionary* myDict= myNdb.getDictionary();
const NdbDictionary::Table *myTable= myDict->getTable(table);
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 char* table)
{
const NdbDictionary::Dictionary* myDict= myNdb.getDictionary();
const NdbDictionary::Table *myTable= myDict->getTable(table);
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 char* table)
{
const NdbDictionary::Dictionary* myDict= myNdb.getDictionary();
const NdbDictionary::Table *myTable= myDict->getTable(table);
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 char* table)
{
const NdbDictionary::Dictionary* myDict= myNdb.getDictionary();
const NdbDictionary::Table *myTable= myDict->getTable(table);
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)
{
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);
}
}
/**************************
* Drop table after usage *
**************************/
static void drop_table(MYSQL &mysql, const char* table)
{
char drop_stmt[75];
sprintf(drop_stmt, "DROP TABLE %s", table);
if (mysql_query(&mysql,drop_stmt))
MYSQLERROR(mysql);
}在 NDB 8.0 之前，此程序无法在同一会话期间连续运行多次（缺陷 #27009386）。