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/* Copyright (C) 2003 MySQL AB
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; version 2 of the License.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */
/**
* ndbapi_async.cpp:
* Illustrates how to use callbacks and error handling using the asynchronous
* part of the NDBAPI.
*
* Classes and methods in NDBAPI used in this example:
*
* Ndb_cluster_connection
* connect()
* wait_until_ready()
*
* Ndb
* init()
* startTransaction()
* closeTransaction()
* sendPollNdb()
* getNdbError()
*
* NdbConnection
* getNdbOperation()
* executeAsynchPrepare()
* getNdbError()
*
* NdbOperation
* insertTuple()
* equal()
* setValue()
*
*/
#include <mysql.h>
#include <mysqld_error.h>
#include <NdbApi.hpp>
#include <iostream> // Used for cout
/**
* Helper sleep function
*/
static void
milliSleep(int milliseconds){
struct timeval sleeptime;
sleeptime.tv_sec = milliseconds / 1000;
sleeptime.tv_usec = (milliseconds - (sleeptime.tv_sec * 1000)) * 1000000;
select(0, 0, 0, 0, &sleeptime);
}
/**
* error printout macro
*/
#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); }
#ifndef DOXYGEN_SHOULD_SKIP_INTERNAL
/**
* callback struct.
* transaction : index of the transaction in transaction[] array below
* data : the data that the transaction was modifying.
* retries : counter for how many times the trans. has been retried
*/
typedef struct {
Ndb * ndb;
int transaction;
int data;
int retries;
} async_callback_t;
/**
* Structure used in "free list" to a NdbTransaction
*/
typedef struct {
NdbTransaction* conn;
int used;
} transaction_t;
/**
* Free list holding transactions
*/
transaction_t transaction[1024]; //1024 - max number of outstanding
//transaction in one Ndb object
#endif
/**
* prototypes
*/
/**
* Prepare and send transaction
*/
int populate(Ndb * myNdb, int data, async_callback_t * cbData);
/**
* Error handler.
*/
bool asynchErrorHandler(NdbTransaction * trans, Ndb* ndb);
/**
* Exit function
*/
void asynchExitHandler(Ndb * m_ndb) ;
/**
* Helper function used in callback(...)
*/
void closeTransaction(Ndb * ndb , async_callback_t * cb);
/**
* Function to create table
*/
void create_table(MYSQL &mysql);
/**
* Function to drop table
*/
void drop_table(MYSQL &mysql);
/**
* stat. variables
*/
int tempErrors = 0;
int permErrors = 0;
void
closeTransaction(Ndb * ndb , async_callback_t * cb)
{
ndb->closeTransaction(transaction[cb->transaction].conn);
transaction[cb->transaction].conn = 0;
transaction[cb->transaction].used = 0;
cb->retries++;
}
/**
* Callback executed when transaction has return from NDB
*/
static void
callback(int result, NdbTransaction* trans, void* aObject)
{
async_callback_t * cbData = (async_callback_t *)aObject;
if (result<0)
{
/**
* Error: Temporary or permanent?
*/
if (asynchErrorHandler(trans, (Ndb*)cbData->ndb))
{
closeTransaction((Ndb*)cbData->ndb, cbData);
while(populate((Ndb*)cbData->ndb, cbData->data, cbData) < 0)
milliSleep(10);
}
else
{
std::cout << "Restore: Failed to restore data "
<< "due to a unrecoverable error. Exiting..." << std::endl;
delete cbData;
asynchExitHandler((Ndb*)cbData->ndb);
}
}
else
{
/**
* OK! close transaction
*/
closeTransaction((Ndb*)cbData->ndb, cbData);
delete cbData;
}
}
/**
* Create table "GARAGE"
*/
void create_table(MYSQL &mysql)
{
while (mysql_query(&mysql,
"CREATE TABLE"
" GARAGE"
" (REG_NO INT UNSIGNED NOT NULL,"
" BRAND CHAR(20) NOT NULL,"
" COLOR CHAR(20) NOT NULL,"
" PRIMARY KEY USING HASH (REG_NO))"
" ENGINE=NDB"))
{
if (mysql_errno(&mysql) != ER_TABLE_EXISTS_ERROR)
MYSQLERROR(mysql);
std::cout << "MySQL Cluster already has example table: GARAGE. "
<< "Dropping it..." << std::endl;
drop_table(mysql);
create_table(mysql);
}
}
/**
* Drop table GARAGE
*/
void drop_table(MYSQL &mysql)
{
if (mysql_query(&mysql, "DROP TABLE GARAGE"))
MYSQLERROR(mysql);
}
void asynchExitHandler(Ndb * m_ndb)
{
if (m_ndb != NULL)
delete m_ndb;
exit(-1);
}
/* returns true if is recoverable (temporary),
* false if it is an error that is permanent.
*/
bool asynchErrorHandler(NdbTransaction * trans, Ndb* ndb)
{
NdbError error = trans->getNdbError();
switch(error.status)
{
case NdbError::Success:
return false;
break;
case NdbError::TemporaryError:
/**
* The error code indicates a temporary error.
* The application should typically retry.
* (Includes classifications: NdbError::InsufficientSpace,
* NdbError::TemporaryResourceError, NdbError::NodeRecoveryError,
* NdbError::OverloadError, NdbError::NodeShutdown
* and NdbError::TimeoutExpired.)
*
* We should sleep for a while and retry, except for insufficient space
*/
if(error.classification == NdbError::InsufficientSpace)
return false;
milliSleep(10);
tempErrors++;
return true;
break;
case NdbError::UnknownResult:
std::cout << error.message << std::endl;
return false;
break;
default:
case NdbError::PermanentError:
switch (error.code)
{
case 499:
case 250:
milliSleep(10);
return true; // SCAN errors that can be retried. Requires restart of scan.
default:
break;
}
//ERROR
std::cout << error.message << std::endl;
return false;
break;
}
return false;
}
static int nPreparedTransactions = 0;
static int MAX_RETRIES = 10;
static int parallelism = 100;
/************************************************************************
* populate()
* 1. Prepare 'parallelism' number of insert transactions.
* 2. Send transactions to NDB and wait for callbacks to execute
*/
int populate(Ndb * myNdb, int data, async_callback_t * cbData)
{
NdbOperation* myNdbOperation; // For operations
const NdbDictionary::Dictionary* myDict= myNdb->getDictionary();
const NdbDictionary::Table *myTable= myDict->getTable("GARAGE");
if (myTable == NULL)
APIERROR(myDict->getNdbError());
async_callback_t * cb;
int retries = 0;
int current = 0;
for(int i=0; i<1024; i++)
{
if(transaction[i].used == 0)
{
current = i;
if (cbData == 0)
{
/**
* We already have a callback
* This is an absolutely new transaction
*/
cb = new async_callback_t;
cb->retries = 0;
}
else
{
/**
* We already have a callback
*/
cb =cbData;
retries = cbData->retries;
}
/**
* Set data used by the callback
*/
cb->ndb = myNdb; //handle to Ndb object so that we can close transaction
// in the callback (alt. make myNdb global).
cb->data = data; //this is the data we want to insert
cb->transaction = current; //This is the number (id) of this transaction
transaction[current].used = 1 ; //Mark the transaction as used
break;
}
}
if(!current)
return -1;
while(retries < MAX_RETRIES)
{
transaction[current].conn = myNdb->startTransaction();
if (transaction[current].conn == NULL) {
/**
* no transaction to close since conn == null
*/
milliSleep(10);
retries++;
continue;
}
myNdbOperation = transaction[current].conn->getNdbOperation(myTable);
if (myNdbOperation == NULL)
{
if (asynchErrorHandler(transaction[current].conn, myNdb))
{
myNdb->closeTransaction(transaction[current].conn);
transaction[current].conn = 0;
milliSleep(10);
retries++;
continue;
}
asynchExitHandler(myNdb);
} // if
if(myNdbOperation->insertTuple() < 0 ||
myNdbOperation->equal("REG_NO", data) < 0 ||
myNdbOperation->setValue("BRAND", "Mercedes") <0 ||
myNdbOperation->setValue("COLOR", "Blue") < 0)
{
if (asynchErrorHandler(transaction[current].conn, myNdb))
{
myNdb->closeTransaction(transaction[current].conn);
transaction[current].conn = 0;
retries++;
milliSleep(10);
continue;
}
asynchExitHandler(myNdb);
}
/*Prepare transaction (the transaction is NOT yet sent to NDB)*/
transaction[current].conn->executeAsynchPrepare(NdbTransaction::Commit,
&callback,
cb);
/**
* When we have prepared parallelism number of transactions ->
* send the transaction to ndb.
* Next time we will deal with the transactions are in the
* callback. There we will see which ones that were successful
* and which ones to retry.
*/
if (nPreparedTransactions == parallelism-1)
{
// send-poll all transactions
// close transaction is done in callback
myNdb->sendPollNdb(3000, parallelism );
nPreparedTransactions=0;
}
else
nPreparedTransactions++;
return 1;
}
std::cout << "Unable to recover from errors. Exiting..." << std::endl;
asynchExitHandler(myNdb);
return -1;
}
int main(int argc, char** argv)
{
if (argc != 3)
{
std::cout << "Arguments are <socket mysqld> <connect_string cluster>.\n";
exit(-1);
}
char * mysqld_sock = argv[1];
const char *connectstring = argv[2];
ndb_init();
MYSQL mysql;
/**************************************************************
* Connect to mysql server and create table *
**************************************************************/
{
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);
mysql_query(&mysql, "CREATE DATABASE TEST_DB");
if (mysql_query(&mysql, "USE TEST_DB") != 0) MYSQLERROR(mysql);
create_table(mysql);
}
/**************************************************************
* Connect to ndb cluster *
**************************************************************/
Ndb_cluster_connection cluster_connection(connectstring);
if (cluster_connection.connect(4, 5, 1))
{
std::cout << "Unable to connect to cluster within 30 secs." << std::endl;
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);
}
Ndb* myNdb = new Ndb( &cluster_connection,
"TEST_DB" ); // Object representing the database
if (myNdb->init(1024) == -1) { // Set max 1024 parallel transactions
APIERROR(myNdb->getNdbError());
}
/**
* Initialise transaction array
*/
for(int i = 0 ; i < 10 ; i++)
{
transaction[i].used = 0;
transaction[i].conn = 0;
}
int i=0;
/**
* Do 10 insert transactions.
*/
while(i < 10)
{
while(populate(myNdb,i,0)<0) // <0, no space on free list. Sleep and try again.
milliSleep(10);
i++;
}
std::cout << "Number of temporary errors: " << tempErrors << std::endl;
delete myNdb;
drop_table(mysql);
}
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