Connection Class Reference

Represents a database connection. More...

#include <Session.h>

Collaboration diagram for Connection:

[legend]

Public Member Functions
	Connection ()
	~Connection ()
DbRetVal	open (const char *username, const char *password)
	opens connection to the database
DbRetVal	close ()
	closes connection to the database and releases all the resources
DatabaseManager *	getDatabaseManager ()
	gets the database manager object.
UserManager *	getUserManager ()
	gets the user manager object.
DbRetVal	startTransaction (IsolationLevel level=READ_COMMITTED)
	Starts a transaction.
DbRetVal	commit ()
	Commits active transaction.
DbRetVal	rollback ()
	Aborts the active transaction.

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Detailed Description

Represents a database connection.

All database operations shall be done within the context of the connection.
Application should first create object of this class for accessing the database.
Each connection has only one active transaction at any given point of time, all
operations which happen using this connection object will be done as part of that
transaction.

Functionality:
1.Connection Management (connect and disconnect)
2.Transaction Management (start, commit, abort)
3.Provides getter methods for database manager and user manager

TODO:
1.Isolation Level support needs to be added. Currently it supports REPEATABLE READ
isolation level as the default. It will soon support READ COMMITTED and
READ UNCOMMITTED isolation levels
2.AutoCommit mode

Note:
SERIALIZABLE isolation level is not supported.

Author:

Prabakaran Thirumalai

Definition at line 61 of file Session.h.

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Constructor & Destructor Documentation

Connection::Connection

(

)

[inline]

Definition at line 65 of file Session.h.

{ session = NULL; }

Connection::~Connection

(

)

Definition at line 21 of file Connection.cxx.

References Index::destroy(), and Session::rollback().

{ 
    if (NULL != session) {
       session->rollback();
       //session->close();
       delete session; 
       session = NULL;
    }
    Index::destroy();
}

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Member Function Documentation

DbRetVal Connection::close

(

)

closes connection to the database and releases all the resources

Returns:

DbRetVal

Definition at line 55 of file Connection.cxx.

References ErrNoConnection, logFinest, logger, OK, Session::rollback(), and Logger::stopLogger().

Referenced by SqlConnection::disconnect(), handleEchoAndComment(), CacheTableLoader::load(), main(), CacheTableLoader::recoverAllCachedTables(), CacheTableLoader::unload(), and verifyPrimKeyFldVal().

{
    if (session == NULL) return ErrNoConnection;
    logFinest(logger, "User logged out");
    logger.stopLogger();
    session->rollback();
    delete session;  // this inturn calls session->close
    session = NULL;
    return OK;
}

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DbRetVal Connection::commit

(

)

Commits active transaction.

It makes all the changes made in the current transaction permanent and
it also releases the locks held by the current transaction.
After a transaction commits, application is required to start another
transaction for further database operations.

Returns:

DbRetVal

Definition at line 86 of file Connection.cxx.

References Session::commit(), and ErrNoConnection.

Referenced by SqlConnection::commit(), getInput(), handleTransaction(), insert(), CacheTableLoader::load(), remove(), CacheTableLoader::unload(), and verifyPrimKeyFldVal().

{
    if (session == NULL) return ErrNoConnection;
    return session->commit();
}

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DatabaseManager * Connection::getDatabaseManager

(

)

gets the database manager object.

Returns:

DatabaseManager

Definition at line 66 of file Connection.cxx.

References Session::getDatabaseManager().

Referenced by getRecordsFromTargetDb(), handleEchoAndComment(), CacheTableLoader::load(), main(), SqlStatement::prepare(), CacheTableLoader::unload(), and verifyPrimKeyFldVal().

{
    if (session == NULL) return NULL;
    return session->getDatabaseManager();
}

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UserManager * Connection::getUserManager

(

)

gets the user manager object.

Returns:

UserManager

Definition at line 72 of file Connection.cxx.

References Session::getUserManager().

{
    if (session == NULL) return NULL;
    return session->getUserManager();
}

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DbRetVal Connection::open	(	const char *	username,
		const char *	password
	)

opens connection to the database

Parameters:

	username	username for authentication
	password	password for authentication

Returns:

DbRetVal

Definition at line 32 of file Connection.cxx.

References Conf::config, ErrAlready, ErrBadArg, Index::init(), logFinest, logger, OK, Session::open(), printError, and Logger::startLogger().

Referenced by SqlConnection::connect(), handleEchoAndComment(), CacheTableLoader::load(), main(), CacheTableLoader::recoverAllCachedTables(), CacheTableLoader::unload(), and verifyPrimKeyFldVal().

{
    if (username == NULL || password == NULL ) 
    {
        printError(ErrBadArg, "Username or password should not be NULL\n");
        return ErrBadArg;
    }
    if (strlen(username) > 64 || strlen(password) >64) return ErrBadArg;
    if (session == NULL) session = new SessionImpl(); 
    else
    {
       printError(ErrAlready, "User already logged in");
       return ErrAlready;
    }
    DbRetVal rv = session->open(username, password);
    if (rv != OK) { delete session; session = NULL; return rv; }
    rv = logger.startLogger(Conf::config.getLogFile());
    if (rv != OK) { delete session; session = NULL; return rv; }
    logFinest(logger, "User logged in %s",username);
    Index::init();
    return OK;
}

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DbRetVal Connection::rollback

(

)

Aborts the active transaction.

undo all the changes made in the current transaction and it also
releases the locks held by the current transaction.
After a transaction rollback, application is required to start another
transaction for further database operations.

Returns:

DbRetVal

Definition at line 93 of file Connection.cxx.

References ErrNoConnection, and Session::rollback().

Referenced by handleTransaction(), main(), remove(), and SqlConnection::rollback().

{
    if (session == NULL) return ErrNoConnection;
    return session->rollback();
}

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DbRetVal Connection::startTransaction

(

IsolationLevel

level = READ_COMMITTED

)

Starts a transaction.

The previous transaction should be either committed or rollback
before startTransaction is called.
Application are required to start transaction before they attempt any
database operation.

Returns:

DbRetVal

Definition at line 78 of file Connection.cxx.

References ErrNoConnection, READ_REPEATABLE, Session::startTransaction(), and WRITE_OSYNC.

Referenced by SqlConnection::beginTrans(), insert(), CacheTableLoader::load(), remove(), CacheTableLoader::unload(), and verifyPrimKeyFldVal().

{
    if (session == NULL) return ErrNoConnection;
    if (level == WRITE_OSYNC) level = READ_REPEATABLE;
    return session->startTransaction(level);
}

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The documentation for this class was generated from the following files:

• include/Session.h
• src/server/Connection.cxx

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