path: root/ndb/include/ndbapi/Ndb.hpp

/* Copyright (C) 2003 MySQL AB

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/**
   @mainpage                            NDB API Programmers' Guide

   This guide assumes a basic familiarity with MySQL Cluster concepts found
   on http://dev.mysql.com/doc/mysql/en/NDBCluster.html .
   Some of the fundamental ones are also described in section @ref secConcepts.

   The NDB API is a MySQL Cluster application interface 
   that implements transactions.
   The NDB API consists of the following fundamental classes:
   - Ndb_cluster_connection, representing a connection to a cluster, 
   - Ndb is the main class, representing a connection to a database, 
   - NdbTransaction represents a transaction, 
   - NdbOperation represents an operation using a primary key,
   - NdbScanOperation represents an operation performing a full table scan.
   - NdbIndexOperation represents an operation using a unique hash index,
   - NdbIndexScanOperation represents an operation performing a scan using
     an ordered index,
   - NdbRecAttr represents an attribute value
   - NdbDictionary represents meta information about tables and attributes.
     
   In addition, the NDB API defines a structure NdbError, which contains the 
   specification for an error.

   It is also possible to receive "events" triggered when data in the database in changed.
   This is done through the NdbEventOperation class.

   There are also some auxiliary classes, which are listed in the class hierarchy.
     
   The main structure of an application program is as follows:
   -# Connect to a cluster using the Ndb_cluster_connection
      object.
   -# Initiate a database connection by constructing and initialising one or more Ndb objects.
   -# Define and execute transactions using the NdbTransaction class.
   -# Delete Ndb objects.
   -# Terminate the connection to the cluster (terminate instance of Ndb_cluster_connection).

   The procedure for using transactions is as follows:
   -# Start transaction (instantiate an NdbTransaction object)
   -# Add and define operations associated with the transaction using instances of one or more of the
      NdbOperation, NdbScanOperation, NdbIndexOperation, and NdbIndexScanOperation classes
   -# Execute transaction (call NdbTransaction::execute())

   The operation can be of two different types, 
   <var>Commit</var> or <var>NoCommit</var>.
   If the operation is of type <var>NoCommit</var>, 
   then the application program executes the operation part of a transaction,
   but without actually committing the transaction.
   After executing a <var>NoCommit</var> operation, the program can continue 
   to add and define more operations to the transaction
   for later execution.

   If the operation is of type <var>Commit</var>, then the transaction is
   immediately committed. The transaction <em>must</em> be closed after it has been 
   commited (event if commit fails), and no further addition or definition of 
   operations for this transaction is allowed.

   @section secSync                     Synchronous Transactions
  
   Synchronous transactions are defined and executed as follows:
  
    -# Start (create) the transaction, which is
       referenced by an NdbTransaction object 
       (typically created using Ndb::startTransaction()).
       At this point, the transaction is only being defined,
       and is not yet sent to the NDB kernel.
    -# Define operations and add them to the transaction, using one or more of
       - NdbTransaction::getNdbOperation()
       - NdbTransaction::getNdbScanOperation()
       - NdbTransaction::getNdbIndexOperation()
       - NdbTransaction::getNdbIndexScanOperation()
       along with the appropriate methods of the respective NdbOperation class 
       (or one possiblt one or more of its subclasses).
       Note that the transaction has still not yet been sent to the NDB kernel.
    -# Execute the transaction, using the NdbTransaction::execute() method.
    -# Close the transaction (call Ndb::closeTransaction()).
  
   For an example of this process, see the program listing in 
   @ref ndbapi_simple.cpp.

   To execute several parallel synchronous transactions, one can either 
   use multiple Ndb objects in several threads, or start multiple 
   application programs.  

   @section secNdbOperations            Operations

   A NdbTransaction consists of a list of operations, each of which is represented 
   by an instance of NdbOperation, NdbScanOperation, NdbIndexOperation, or
   NdbIndexScanOperation.

   <h3>Single row operations</h3>
   After the operation is created using NdbTransaction::getNdbOperation()
   (or NdbTransaction::getNdbIndexOperation()), it is defined in the following 
   three steps:
   -# Define the standard operation type, using NdbOperation::readTuple()
   -# Specify search conditions, using NdbOperation::equal()
   -# Specify attribute actions, using NdbOperation::getValue()

   Here are two brief examples illustrating this process. For the sake of 
   brevity, we omit error handling.
   
   This first example uses an NdbOperation:
   @code
     // 1. Retrieve table object
     myTable= myDict->getTable("MYTABLENAME");

     // 2. Create
     myOperation= myTransaction->getNdbOperation(myTable);
    
     // 3. Define type of operation and lock mode
     myOperation->readTuple(NdbOperation::LM_Read);

     // 4. Specify Search Conditions
     myOperation->equal("ATTR1", i);
    
     // 5. Attribute Actions
     myRecAttr= myOperation->getValue("ATTR2", NULL);
   @endcode
   For additional examples of this sort, see @ref ndbapi_simple.cpp.

   The second example uses an NdbIndexOperation:
   @code
     // 1. Retrieve index object
     myIndex= myDict->getIndex("MYINDEX", "MYTABLENAME");

     // 2. Create
     myOperation= myTransaction->getNdbIndexOperation(myIndex);

     // 3. Define type of operation and lock mode
     myOperation->readTuple(NdbOperation::LM_Read);

     // 4. Specify Search Conditions
     myOperation->equal("ATTR1", i);

     // 5. Attribute Actions 
     myRecAttr = myOperation->getValue("ATTR2", NULL);
   @endcode
   Another example of this second type can be found in 
   @ref ndbapi_simple_index.cpp.

   We will now discuss in somewhat greater detail each step involved in the 
   creation and use of synchronous transactions.

   <h4>Step 1: Define single row operation type</h4>
   The following operation types are supported:
    -# NdbOperation::insertTuple() : 
       inserts a non-existing tuple
    -# NdbOperation::writeTuple() : 
       updates an existing tuple if is exists,
       otherwise inserts a new tuple
    -# NdbOperation::updateTuple() : 
       updates an existing tuple
    -# NdbOperation::deleteTuple() : 
       deletes an existing tuple
    -# NdbOperation::readTuple() : 
       reads an existing tuple with specified lock mode

   All of these operations operate on the unique tuple key.
   (When NdbIndexOperation is used then all of these operations 
   operate on a defined unique hash index.)

   @note If you want to define multiple operations within the same transaction,
         then you need to call NdbTransaction::getNdbOperation() or
	 NdbTransaction::getNdbIndexOperation() for each operation.

   <h4>Step 2: Specify Search Conditions</h4>
   The search condition is used to select tuples. Search conditions are set using NdbOperation::equal().

   <h4>Step 3: Specify Attribute Actions</h4>
   Next, it is necessary to determine which attributes should be read or updated.
   It is important to remember that: 
   - Deletes can neither read nor set values, but only delete them
   - Reads can only read values
   - Updates can only set values
   Normally the attribute is identified by name, but it is
   also possible to use the attribute's identity to determine the
   attribute.

   NdbOperation::getValue() returns an NdbRecAttr object
   containing the read value.
   To obtain the actual value, one of two methods can be used;
   the application can either
   - use its own memory (passed through a pointer aValue) to
     NdbOperation::getValue(), or
   - receive the attribute value in an NdbRecAttr object allocated
     by the NDB API.

   The NdbRecAttr object is released when Ndb::closeTransaction()
   is called.
   Thus, the application cannot reference this object following
   any subsequent call to Ndb::closeTransaction().
   Attempting to read data from an NdbRecAttr object before
   calling NdbTransaction::execute() yields an undefined result.


   @subsection secScan              Scan Operations 
   
   Scans are roughly the equivalent of SQL cursors, providing a means to
   preform high-speed row processing. A scan can be performed 
   on either a table (using @ref NdbScanOperation) or 
   an ordered index (by means of an @ref NdbIndexScanOperation).

   Scan operations are characterised by the following:
   - They can perform only reads (shared, exclusive or dirty)
   - They can potentially work with multiple rows
   - They can be used to update or delete multiple rows
   - They can operate on several nodes in parallel

   After the operation is created using NdbTransaction::getNdbScanOperation()
   (or NdbTransaction::getNdbIndexScanOperation()), 
   it is carried out in the following three steps:
   -# Define the standard operation type, using NdbScanOperation::readTuples()
   -# Specify search conditions, using @ref NdbScanFilter and/or 
      @ref NdbIndexScanOperation::setBound()
   -# Specify attribute actions, using NdbOperation::getValue()
   -# Executing the transaction, using NdbTransaction::execute()
   -# Traversing the result set by means of succssive calls to 
      NdbScanOperation::nextResult()

   Here are two brief examples illustrating this process. Once again, in order
   to keep things relatively short and simple, we will forego any error handling.
   
   This first example performs a table scan, using an NdbScanOperation:
   @code
     // 1. Retrieve table object
     myTable= myDict->getTable("MYTABLENAME");
    
     // 2. Create
     myOperation= myTransaction->getNdbScanOperation(myTable);
    
     // 3. Define type of operation and lock mode
     myOperation->readTuples(NdbOperation::LM_Read);

     // 4. Specify Search Conditions
     NdbScanFilter sf(myOperation);
     sf.begin(NdbScanFilter::OR);
     sf.eq(0, i);   // Return rows with column 0 equal to i or
     sf.eq(1, i+1); // column 1 equal to (i+1)
     sf.end();

     // 5. Attribute Actions
     myRecAttr= myOperation->getValue("ATTR2", NULL);
   @endcode

   Our second example uses an NdbIndexScanOperation to perform an index scan:
   @code
     // 1. Retrieve index object
     myIndex= myDict->getIndex("MYORDEREDINDEX", "MYTABLENAME");

     // 2. Create
     myOperation= myTransaction->getNdbIndexScanOperation(myIndex);

     // 3. Define type of operation and lock mode
     myOperation->readTuples(NdbOperation::LM_Read);

     // 4. Specify Search Conditions
     // All rows with ATTR1 between i and (i+1)
     myOperation->setBound("ATTR1", NdbIndexScanOperation::BoundGE, i);
     myOperation->setBound("ATTR1", NdbIndexScanOperation::BoundLE, i+1);

     // 5. Attribute Actions 
     myRecAttr = MyOperation->getValue("ATTR2", NULL);
   @endcode

   Some additional discussion of each step required to perform a scan follows:

   <h4>Step 1: Define Scan Operation Type</h4>
   It is important to remember that only a single operation is supported for each scan operation 
   (@ref NdbScanOperation::readTuples() or @ref NdbIndexScanOperation::readTuples()).

   @note If you want to define multiple scan operations within the same 
         transaction, then you need to call 
	 NdbTransaction::getNdbScanOperation() or 
	 NdbTransaction::getNdbIndexScanOperation() separately for <b>each</b> operation.

   <h4>Step 2: Specify Search Conditions</h4>
   The search condition is used to select tuples.
   If no search condition is specified, the scan will return all rows
   in the table.

   The search condition can be an @ref NdbScanFilter (which can be used on both
   @ref NdbScanOperation and @ref NdbIndexScanOperation) or bounds which
   can only be used on index scans (@ref NdbIndexScanOperation::setBound()).
   An index scan can use both NdbScanFilter and bounds.

   @note When NdbScanFilter is used, each row is examined, whether or not it is
   actually returned. However, when using bounds, only rows within the bounds will be examined.

   <h4>Step 3: Specify Attribute Actions</h4>

   Next, it is necessary to define which attributes should be read.
   As with transaction attributes, scan attributes are defined by name but it is
   also possible to use the attributes' identities to define attributes.

   As previously discussed (see @ref secSync), the value read is returned as 
   an NdbRecAttr object by the NdbOperation::getValue() method.

   <h3>Using Scan to Update/Delete</h3>
   Scanning can also be used to update or delete rows.
   This is performed by
   -# Scanning using exclusive locks (using NdbOperation::LM_Exclusive)
   -# When iterating through the result set, for each row optionally calling 
      either NdbScanOperation::updateCurrentTuple() or 
      NdbScanOperation::deleteCurrentTuple()
   -# (If performing NdbScanOperation::updateCurrentTuple():) 
      Setting new values for records simply by using @ref NdbOperation::setValue().
      NdbOperation::equal() should <em>not</em> be called in such cases, as the primary 
      key is retrieved from the scan.

   @note The actual update or delete will not be performed until the next 
   call to NdbTransaction::execute(), just as with single row operations. 
   NdbTransaction::execute() also must be called before any locks are released;
   see @ref secScanLocks for more information.

   <h4>Features Specific to Index Scans</h4> 
   
   When performing an index scan, it is possible to 
   scan only a subset of a table using @ref NdbIndexScanOperation::setBound().
   In addition, result sets can be sorted in either ascending or descending order, using
   @ref NdbIndexScanOperation::readTuples(). Note that rows are returned unordered 
   by default, that is, unless <var>sorted</var> is set to <b>true</b>.
   It is also important to note that, when using NdbIndexScanOperation::BoundEQ 
   on a partition key, only fragments containing rows will actually be scanned.
   
   @note When performing a sorted scan, any value passed as the 
   NdbIndexScanOperation::readTuples() method's <code>parallel</code> argument 
   will be ignored and maximum parallelism will be used instead. In other words, all 
   fragments which it is possible to scan will be scanned simultaneously and in parallel 
   in such cases.

   @subsection secScanLocks Lock handling with scans

   Performing scans on either a tables or an index has the potential 
   return a great many records; however, Ndb will lock only a predetermined 
   number of rows per fragment at a time.
   How many rows will be locked per fragment is controlled by the 
   <var>batch</var> parameter passed to NdbScanOperation::readTuples().

   In order to allow the application to handle how locks are released, 
   NdbScanOperation::nextResult() has a Boolean parameter <var>fetch_allow</var>.
   If NdbScanOperation::nextResult() is called with <var>fetch_allow</var> equal to 
   <b>false</b>, then no locks may be released as result of the function call. 
   Otherwise the locks for the current batch may be released.

   This next example shows a scan delete that handle locks in an efficient manner.
   For the sake of brevity, we omit error-handling.
   @code
     int check;

     // Outer loop for each batch of rows
     while((check = MyScanOperation->nextResult(true)) == 0)
     {
       do
       {
         // Inner loop for each row within batch
         MyScanOperation->deleteCurrentTuple();
       } while((check = MyScanOperation->nextResult(false)) == 0);

       // When no more rows in batch, exeute all defined deletes       
       MyTransaction->execute(NoCommit);
     }
   @endcode

   See @ref ndbapi_scan.cpp for a more complete example of a scan.

   @section secError                    Error Handling

   Errors can occur either when operations making up a transaction are being 
   defined, or when the transaction is actually being executed. Catching and 
   handling either sort of error requires testing the value returned by 
   NdbTransaction::execute(), and then, if an error is indicated (that is, 
   if this value is equal to -1), using the following two methods in order to 
   identify the error's type and location:

   - NdbTransaction::getNdbErrorOperation() returns a reference to the 
     operation causing the most recent error.
   - NdbTransaction::getNdbErrorLine() yields the method number of the 
     erroneous method in the operation.
   
   This short example illustrates how to detect an error and to use these 
   two methods to identify it:

   @code
     theTransaction = theNdb->startTransaction();
     theOperation = theTransaction->getNdbOperation("TEST_TABLE");
     if (theOperation == NULL) goto error;
     theOperation->readTuple(NdbOperation::LM_Read);
     theOperation->setValue("ATTR_1", at1);
     theOperation->setValue("ATTR_2", at1);  //  Error occurs here
     theOperation->setValue("ATTR_3", at1);
     theOperation->setValue("ATTR_4", at1);
    
     if (theTransaction->execute(Commit) == -1) {
       errorLine = theTransaction->getNdbErrorLine();
       errorOperation = theTransaction->getNdbErrorOperation();
     }
   @endcode

   Here <code>errorLine</code> will be 3, as the error occurred in the 
   third method called on the NdbOperation object (in this case, 
   <code>theOperation</code>); if the result of 
   NdbTransaction::getNdbErrorLine() is 0, this means that the error 
   occurred when the operations were executed. In this example, 
   <code>errorOperation</code> will be a pointer to the <code>theOperation</code> 
   object. The NdbTransaction::getNdbError() method returns an NdbError 
   object providing information about the error.

   @note Transactions are <b>not</b> automatically closed when an error occurs. Call
   Ndb::closeTransaction() to close the transaction.

   One recommended way to handle a transaction failure 
   (i.e. an error is reported) is to:
   -# Rollback transaction (call NdbTransaction::execute() with a special parameter)
   -# Close transaction (call NdbTransaction::closeTransaction())
   -# If the error was temporary, attempt to restart the transaction

   Several errors can occur when a transaction contains multiple 
   operations which are simultaneously executed.
   In this case the application has to go through all operations
   and query their NdbError objects to find out what really happened.

   It is also important to note that errors can occur even when a commit is 
   reported as successful. In order to handle such situations, the NDB API 
   provides an additional NdbTransaction::commitStatus() method to check the 
   transactions's commit status.

******************************************************************************/

/**
 * @page ndbapi_simple.cpp ndbapi_simple.cpp
 * @include ndbapi_simple.cpp 
 */

#ifndef DOXYGEN_SHOULD_SKIP_INTERNAL
/**
 * @page ndbapi_async.cpp ndbapi_async.cpp
 * @include ndbapi_async.cpp 
 */
/**
 * @page ndbapi_async1.cpp ndbapi_async1.cpp
 * @include ndbapi_async1.cpp 
 */
#endif

/**
 * @page ndbapi_retries.cpp ndbapi_retries.cpp
 * @include ndbapi_retries.cpp 
 */

/**
 * @page ndbapi_simple_index.cpp ndbapi_simple_index.cpp
 * @include ndbapi_simple_index.cpp 
 */

/**
 * @page ndbapi_scan.cpp ndbapi_scan.cpp
 * @include ndbapi_scan.cpp
 */

/**
 * @page ndbapi_event.cpp ndbapi_event.cpp
 * @include ndbapi_event.cpp
 */


/**
   @page secAdapt  Adaptive Send Algorithm

   At the time of "sending" a transaction 
   (using NdbTransaction::execute()), the transactions 
   are in reality <em>not</em> immediately transfered to the NDB Kernel.  
   Instead, the "sent" transactions are only kept in a 
   special send list (buffer) in the Ndb object to which they belong.
   The adaptive send algorithm decides when transactions should
   actually be transferred to the NDB kernel.
  
   The NDB API is designed as a multi-threaded interface and so
   it is often desirable to transfer database operations from more than 
   one thread at a time. 
   The NDB API keeps track of which Ndb objects are active in transferring
   information to the NDB kernel and the expected amount of threads to 
   interact with the NDB kernel.
   Note that a given instance of Ndb should be used in at most one thread; 
   different threads should <em>not</em> use the same Ndb object.
  
   There are four conditions leading to the transfer of database 
   operations from Ndb object buffers to the NDB kernel:
   -# The NDB Transporter (TCP/IP, OSE, SCI or shared memory)
      decides that a buffer is full and sends it off. 
      The buffer size is implementation-dependent and
      may change between MySQL Cluster releases.
      On TCP/IP the buffer size is usually around 64 KB;
      on OSE/Delta it is usually less than 2000 bytes. 
      Since each Ndb object provides a single buffer per storage node, 
      the notion of a "full" buffer is local to this storage node.
   -# The accumulation of statistical data on transferred information
      may force sending of buffers to all storage nodes.
   -# Every 10 ms, a special transmission thread checks whether or not
      any send activity has occurred. If not, then the thread will 
      force transmission to all nodes. 
      This means that 20 ms is the maximum time database operations 
      are kept waiting before being sent off. The 10-millisecond limit 
      is likely to become a configuration parameter in
      future releases of MySQL Cluster; however, for checks that
      are more frequent than each 10 ms, 
      additional support from the operating system is required.
   -# For methods that are affected by the adaptive send alorithm
      (such as NdbTransaction::execute()), there is a <var>force</var> 
      parameter 
      that overrides its default behaviour in this regard and forces 
      immediate transmission to all nodes. See the inidvidual NDB API class 
      listings for more information.

   @note The conditions listed above are subject to change in future releases 
   of MySQL Cluster.
*/

#ifndef DOXYGEN_SHOULD_SKIP_INTERNAL
/**

   For each of these "sent" transactions, there are three 
   possible states:
   -# Waiting to be transferred to NDB Kernel.
   -# Has been transferred to the NDB Kernel and is currently 
      being processed.
   -# Has been transferred to the NDB Kernel and has 
      finished processing.
      Now it is waiting for a call to a poll method.  
      (When the poll method is invoked, 
      then the transaction callback method will be executed.)
      
   The poll method invoked (either Ndb::pollNdb() or Ndb::sendPollNdb())
   will return when:
   -# at least 'minNoOfEventsToWakeup' of the transactions
      in the send list have transitioned to state 3 as described above, and 
   -# all of these transactions have executed their callback methods.
*/
#endif

/**
   @page secConcepts  MySQL Cluster Concepts

   The <em>NDB Kernel</em> is the collection of storage nodes
   belonging to a MySQL Cluster.
   The application programmer can for most purposes view the
   set of all storage nodes as a single entity.
   Each storage node is made up of three main components:
   - TC : The transaction co-ordinator
   - ACC : Index storage component
   - TUP : Data storage component

   When an application program executes a transaction,
   it connects to one transaction co-ordinator on one storage node.  
   Usually, the programmer does not need to specify which TC should be used, 
   but in some cases when performance is important, the programmer can
   provide "hints" to use a certain TC.  
   (If the node with the desired transaction co-ordinator is down, then another TC will 
   automatically take over the work.)

   Every storage node has an ACC and a TUP which store 
   the indexes and data portions of the database table fragment.
   Even though one TC is responsible for the transaction,
   several ACCs and TUPs on other storage nodes might be involved in the 
   execution of the transaction.


   @section secNdbKernelConnection   Selecting a Transaction Co-ordinator 

   The default method is to select the transaction co-ordinator (TC) determined to be
   the "closest" storage node, using a heuristic for proximity based on
   the type of transporter connection. In order of closest to most distant, these are
   - SCI 
   - SHM
   - TCP/IP (localhost)
   - TCP/IP (remote host)
   If there are several connections available with the same proximity, they will each be 
   selected in a round robin fashion for every transaction. Optionally
   one may set the method for TC selection to round-robin mode, where each new set of 
   transactions is placed on the next DB node. The pool of connections from which this
   selection is made consists of all available connections.
   
   As noted previously, the application programmer can provide hints to the NDB API as to 
   which transaction co-ordinator it should use. This is done by
   providing a <em>table</em> and <em>partition key</em> 
   (usually the primary key).
   By using the primary key as the partition key, 
   the transaction will be placed on the node where the primary replica
   of that record resides.
   Note that this is only a hint; the system can be 
   reconfigured at any time, in which case the NDB API will choose a transaction
   co-ordinator without using the hint.
   For more information, see NdbDictionary::Column::getPartitionKey() and
   Ndb::startTransaction(). The application programmer can specify
   the partition key from SQL by using the construct, 
   <code>CREATE TABLE ... ENGINE=NDB PARTITION BY KEY (<var>attribute-list</var>);</code>.


   @section secRecordStruct          NDB Record Structure 
   The NDB Cluster engine used by MySQL Cluster is a relational database engine
   storing records in tables just as with any other RDBMS.
   Table rows represent records as tuples of relational data.
   When a new table is created, its attribute schema is specified for the table as a whole,
   and thus each record of the table has the same structure. Again, this is typical
   of relational databases, and NDB is no different in this regard.
   

   @subsection secKeys               Primary Keys
   Each record has from 1 up to 32 attributes which belong
   to the primary key of the table.
   
   @section secTrans                 Transactions

   Transactions are committed first to main memory, 
   and then to disk after a global checkpoint (GCP) is issued.
   Since all data is (in most NDB Cluster configurations) 
   synchronously replicated and stored on multiple NDB nodes,
   the system can still handle processor failures without loss 
   of data.
   However, in the case of a system failure (e.g. the whole system goes down), 
   then all (committed or not) transactions occurring since the latest GCP are lost.


   @subsection secConcur                Concurrency Control
   NDB Cluster uses pessimistic concurrency control based on locking.
   If a requested lock (implicit and depending on database operation)
   cannot be attained within a specified time, 
   then a timeout error occurs.

   Concurrent transactions as requested by parallel application programs and 
   thread-based applications can sometimes deadlock when they try to access 
   the same information simultaneously.
   Thus, applications need to be written in a manner so that timeout errors
   occurring due to such deadlocks are handled gracefully. This generally
   means that the transaction encountering a timeout should be rolled back 
   and restarted.


   @section secHint                 Hints and Performance

   Placing the transaction co-ordinator in close proximity
   to the actual data used in the transaction can in many cases
   improve performance significantly. This is particularly true for
   systems using TCP/IP. For example, a Solaris system using a single 500 MHz processor
   has a cost model for TCP/IP communication which can be represented by the formula

     <code>[30 microseconds] + ([100 nanoseconds] * [<var>number of bytes</var>])</code>

   This means that if we can ensure that we use "popular" links we increase
   buffering and thus drastically reduce the communication cost.
   The same system using SCI has a different cost model:

     <code>[5 microseconds] + ([10 nanoseconds] * [<var>number of bytes</var>])</code>

   Thus, the efficiency of an SCI system is much less dependent on selection of 
   transaction co-ordinators. 
   Typically, TCP/IP systems spend 30-60% of their working time on communication,
   whereas for SCI systems this figure is closer to 5-10%. 
   Thus, employing SCI for data transport means that less care from the NDB API 
   programmer is required and greater scalability can be achieved, even for 
   applications using data from many different parts of the database.

   A simple example is an application that uses many simple updates where
   a transaction needs to update one record. 
   This record has a 32 bit primary key, 
   which is also the partition key. 
   Then the keyData will be the address of the integer 
   of the primary key and keyLen will be 4.
*/

#ifndef DOXYGEN_SHOULD_SKIP_INTERNAL
/**
   (A transaction's execution can also be divided into three 
   steps: prepare, send, and poll. This allows us to perform asynchronous
   transactions.  More about this later.)
*/
#endif
#ifndef DOXYGEN_SHOULD_SKIP_INTERNAL
/**
   Another way to execute several parallel transactions is to use
   asynchronous transactions.
*/
#endif  
#ifndef DOXYGEN_SHOULD_SKIP_INTERNAL
/**
   Operations are of two different kinds:
   -# standard operations, and
   -# interpreted program operations.
*/
#endif
#ifndef DOXYGEN_SHOULD_SKIP_INTERNAL
/**
   <h3>Interpreted Program Operations</h3>
   The following types of interpreted program operations exist:
    -# NdbOperation::interpretedUpdateTuple :
       updates a tuple using an interpreted program
    -# NdbOperation::interpretedDeleteTuple :
       delete a tuple using an interpreted program

   The operations interpretedUpdateTuple and interpretedDeleteTuple both
   work using the unique tuple key.

   These <em>interpreted programs</em> 
   make it possible to perform computations
   inside the NDB Cluster Kernel instead of in the application
   program.
   This is sometimes very effective, since no intermediate results
   are sent to the application, only the final result.


  <h3>Interpreted Update and Delete</h3>

   Operations for interpreted updates and deletes must follow a
   certain order when defining operations on a tuple.
   As for read and write operations,
   one must first define the operation type and then the search key.
   -# The first step is to define the initial readings.
      In this phase it is only allowed to use the
      NdbOperation::getValue method.
      This part might be empty.
   -# The second step is to define the interpreted part.
      The methods supported are the methods listed below except
      NdbOperation::def_subroutine and NdbOperation::ret_sub
      which can only be used in a subroutine.
      NdbOperation::incValue and NdbOperation::subValue
      increment and decrement attributes
      (currently only unsigned integers supported).
      This part can also be empty since interpreted updates
      can be used for reading and updating the same tuple.
      <p>
      Even though getValue and setValue are not really interpreted
      program instructions, it is still allowed to use them as
      the last instruction of the program.
      (If a getValue or setValue is found when an interpret_exit_ok
      could have been issued then the interpreted_exit_ok
      will be inserted.
      A interpret_exit_ok should be viewed as a jump to the first
      instruction after the interpreted instructions.)
   -# The third step is to define all updates without any
      interpreted program instructions.
      Here a set of NdbOperation::setValue methods are called.
      There might be zero such calls.
   -# The fourth step is the final readings.
      The initial readings reads the initial value of attributes
      and the final readings reads them after their updates.
      There might be zero NdbOperation::getValue calls.
   -# The fifth step is possible subroutine definitions using
      NdbOperation::def_subroutine and NdbOperation::ret_sub.
*/
#endif
#ifndef DOXYGEN_SHOULD_SKIP_INTERNAL
/**
   <h3>Interpreted Programs</h3>
   Interpretation programs are executed in a
   register-based virtual machine.
   The virtual machine has eight 64 bit registers numbered 0-7.
   Each register contains type information which is used both
   for type conversion and for type checking.

   @note Arrays are currently <b>not</b> supported in the virtual machine.
         Currently only unsigned integers are supported and of size
         maximum 64 bits.

   All errors in the interpretation program will cause a
   transaction abort, but will not affect any other transactions.

   The following are legal interpreted program instructions:
   -# incValue        : Add to an attribute
   -# subValue        : Subtract from an attribute
   -# def_label       : Define a label in the interpreted program
   -# add_reg         : Add two registers
   -# sub_reg         : Subtract one register from another
   -# load_const_u32  : Load an unsigned 32 bit value into a register
   -# load_const_u64  : Load an unsigned 64 bit value into a register
   -# load_const_null : Load a NULL value into a register
   -# read_attr       : Read attribute value into a register
   -# write_attr      : Write a register value into an attribute
   -# branch_ge       : Compares registers and possibly jumps to specified label
   -# branch_gt       : Compares registers and possibly jumps to specified label
   -# branch_le       : Compares registers and possibly jumps to specified label
   -# branch_lt       : Compares registers and possibly jumps to specified label
   -# branch_eq       : Compares registers and possibly jumps to specified label
   -# branch_ne       : Compares registers and possibly jumps to specified label
   -# branch_ne_null  : Jumps if register does not contain NULL value
   -# branch_eq_null  : Jumps if register contains NULL value
   -# branch_label    : Unconditional jump to label
   -# interpret_exit_ok  : Exit interpreted program
                           (approving tuple if used in scan)
   -# interpret_exit_nok : Exit interpreted program
                           (disqualifying tuple if used in scan)

   There are also three instructions for subroutines, which
   are described in the next section.

   @subsection subsubSub                Interpreted Programs: Subroutines

   The following are legal interpreted program instructions for
   subroutines:
   -# NdbOperation::def_subroutine : 
      Defines start of subroutine in interpreted program code
   -# NdbOperation::call_sub : 
      Calls a subroutine
   -# NdbOperation::ret_sub : 
      Return from subroutine

   The virtual machine executes subroutines using a stack for
   its operation.
   The stack allows for up to 24 subroutine calls in succession.
   Deeper subroutine nesting will cause an abort of the transaction.

   All subroutines starts with the instruction
   NdbOperation::def_subroutine and ends with the instruction
   NdbOperation::ret_sub.
   If it is necessary to return earlier in the subroutine
   it has to be done using a branch_label instruction
   to a label defined right before the 
   NdbOperation::ret_sub instruction.

   @note The subroutines are automatically numbered starting with 0.
         The parameter used by NdbOperation::def_subroutine 
	 should match the automatic numbering to make it easier to 
	 debug the interpreted program.
*/
#endif

#ifndef DOXYGEN_SHOULD_SKIP_INTERNAL
/**
   @section secAsync                    Asynchronous Transactions
   The asynchronous interface is used to increase the speed of
   transaction executing by better utilizing the connection
   between the application and the NDB Kernel.
   The interface is used to send many transactions 
   at the same time to the NDB kernel.  
   This is often much more efficient than using synchronous transactions.
   The main reason for using this method is to ensure that 
   Sending many transactions at the same time ensures that bigger 
   chunks of data are sent when actually sending and thus decreasing 
   the operating system overhead.

   The synchronous call to NdbTransaction::execute 
   normally performs three main steps:<br>
   -# <b>Prepare</b> 
      Check transaction status
      - if problems, abort the transaction
      - if ok, proceed
   -# <b>Send</b> 
      Send the defined operations since last execute
      or since start of transaction.
   -# <b>Poll</b>
      Wait for response from NDB kernel.

   The asynchronous method NdbTransaction::executeAsynchPrepare 
   only perform step 1.
   (The abort part in step 1 is only prepared for.  The actual 
   aborting of the transaction is performed in a later step.)

   Asynchronous transactions are defined and executed 
   in the following way.
   -# Start (create) transactions (same way as for the 
       synchronous transactions)
   -# Add and define operations (also as in the synchronous case)
   -# <b>Prepare</b> transactions 
       (using NdbTransaction::executeAsynchPrepare or 
       NdbTransaction::executeAsynch)
   -# <b>Send</b> transactions to NDB Kernel
       (using Ndb::sendPreparedTransactions, 
       NdbTransaction::executeAsynch, or Ndb::sendPollNdb)
   -# <b>Poll</b> NDB kernel to find completed transactions 
       (using Ndb::pollNdb or Ndb::sendPollNdb)
   -# Close transactions (same way as for the synchronous transactions)

   See example program in section @ref ndbapi_example2.cpp.
   
   This prepare-send-poll protocol actually exists in four variants:
   - (Prepare-Send-Poll).  This is the one-step variant provided
     by synchronous transactions.
   - (Prepare-Send)-Poll.  This is the two-step variant using
     NdbTransaction::executeAsynch and Ndb::pollNdb.
   - Prepare-(Send-Poll).  This is the two-step variant using
     NdbTransaction::executeAsynchPrepare and Ndb::sendPollNdb.
   - Prepare-Send-Poll.  This is the three-step variant using
     NdbTransaction::executeAsynchPrepare, Ndb::sendPreparedTransactions, and
     Ndb::pollNdb.
  
   Transactions first has to be prepared by using method
   NdbTransaction::executeAsynchPrepare or NdbTransaction::executeAsynch.
   The difference between these is that 
   NdbTransaction::executeAsynch also sends the transaction to 
   the NDB kernel.
   One of the arguments to these methods is a callback method.
   The callback method is executed during polling (item 5 above).
  
   Note that NdbTransaction::executeAsynchPrepare does not 
   send the transaction to the NDB kernel.  When using 
   NdbTransaction::executeAsynchPrepare, you either have to call 
   Ndb::sendPreparedTransactions or Ndb::sendPollNdb to send the 
   database operations.
   (Ndb::sendPollNdb also polls Ndb for completed transactions.)
  
   The methods Ndb::pollNdb and Ndb::sendPollNdb checks if any 
   sent transactions are completed.  The method Ndb::sendPollNdb 
   also send all prepared transactions before polling NDB.
   Transactions still in the definition phase (i.e. items 1-3 above, 
   transactions which has not yet been sent to the NDB kernel) are not 
   affected by poll-calls.
   The poll method invoked (either Ndb::pollNdb or Ndb::sendPollNdb)
   will return when:
    -# at least 'minNoOfEventsToWakeup' of the transactions
       are finished processing, and
    -# all of these transactions have executed their 
       callback methods.
  
   The poll method returns the number of transactions that 
   have finished processing and executed their callback methods.

   @note When an asynchronous transaction has been started and sent to
         the NDB kernel, it is not allowed to execute any methods on
         objects belonging to this transaction until the transaction
         callback method have been executed.
         (The transaction is stated and sent by either
	 NdbTransaction::executeAsynch or through the combination of
         NdbTransaction::executeAsynchPrepare and either
         Ndb::sendPreparedTransactions or Ndb::sendPollNdb).

   More about how transactions are sent the NDB Kernel is 
   available in section @ref secAdapt.
*/
#endif


/**
   
   Put this back when real array ops are supported
   i.e. get/setValue("kalle[3]");

   @subsection secArrays             Array Attributes
   A table attribute in NDB Cluster can be of type <var>Array</var>,
   meaning that the attribute consists of an ordered sequence of 
   elements. In such cases, <var>attribute size</var> is the size
   (expressed in bits) of any one element making up the array; the 
   <var>array size</var> is the number of elements in the array.

*/

#ifndef Ndb_H
#define Ndb_H

#include <ndb_types.h>
#include <ndbapi_limits.h>
#include <ndb_cluster_connection.hpp>
#include <NdbError.hpp>
#include <NdbDictionary.hpp>

class NdbObjectIdMap;
class NdbOperation;
class NdbEventOperationImpl;
class NdbScanOperation;
class NdbIndexScanOperation;
class NdbIndexOperation;
class NdbTransaction;
class NdbApiSignal;
class NdbRecAttr;
class NdbLabel;
class NdbBranch;
class NdbSubroutine;
class NdbCall;
class Table;
class BaseString;
class NdbEventOperation;
class NdbBlob;
class NdbReceiver;

typedef void (* NdbEventCallback)(NdbEventOperation*, Ndb*, void*);


#if defined NDB_OSE
/**
 * Default time to wait for response after request has been sent to 
 * NDB Cluster (Set to 10 seconds usually, but to 100 s in 
 * the OSE operating system)
 */
#define WAITFOR_RESPONSE_TIMEOUT 100000 // Milliseconds
#else
#define WAITFOR_RESPONSE_TIMEOUT 120000 // Milliseconds
#endif

#define NDB_MAX_INTERNAL_TABLE_LENGTH NDB_MAX_DATABASE_NAME_SIZE + \
                                      NDB_MAX_SCHEMA_NAME_SIZE + \
                                      NDB_MAX_TAB_NAME_SIZE*2

/**
 * @class Ndb 
 * @brief Represents the NDB kernel and is the main class of the NDB API.
 *
 * Always start your application program by creating an Ndb object. 
 * By using several Ndb objects it is possible to design 
 * a multi-threaded application, but note that Ndb objects 
 * cannot be shared by several threads. 
 * Different threads should use different Ndb objects. 
 * A thread might however use multiple Ndb objects.
 * Currently there is a limit of maximum 128 Ndb objects 
 * per application process.
 *
 * @note It is not allowed to call methods in the NDB API 
 *       on the same Ndb object in different threads 
 *       simultaneously (without special handling of the 
 *       Ndb object).
 *
 * @note The Ndb object is multi-thread safe in the following manner. 
 *       Each Ndb object can ONLY be handled in one thread. 
 *       If an Ndb object is handed over to another thread then the 
 *       application must ensure that a memory barrier is used to 
 *       ensure that the new thread see all updates performed by 
 *       the previous thread. 
 *       Semaphores, mutexes and so forth are easy ways of issuing memory 
 *       barriers without having to bother about the memory barrier concept.
 *
 */

#ifndef DOXYGEN_SHOULD_SKIP_INTERNAL
// to be documented later
/*
 * If one Ndb object is used to handle parallel transactions through the 
 * asynchronous programming interface, please read the notes regarding
 * asynchronous transactions (Section @ref secAsync).
 * The asynchronous interface provides much higher performance 
 * in some situations, but is more complicated for the application designer. 
 *
 * @note Each Ndb object should either use the methods for 
 *       asynchronous transaction or the methods for 
 *       synchronous transactions but not both.
 */
#endif

class Ndb
{
#ifndef DOXYGEN_SHOULD_SKIP_INTERNAL
  friend class NdbReceiver;
  friend class NdbOperation;
  friend class NdbEventOperationImpl;
  friend class NdbTransaction;
  friend class Table;
  friend class NdbApiSignal;
  friend class NdbIndexOperation;
  friend class NdbScanOperation;
  friend class NdbIndexScanOperation;
  friend class NdbDictionaryImpl;
  friend class NdbDictInterface;
  friend class NdbBlob;
#endif

public:
  /** 
   * @name General 
   * @{
   */
  /**
   * The Ndb object represents a connection to a database.
   *
   * @note The init() method must be called before the Ndb object may actually be used.
   *
   * @param ndb_cluster_connection is a connection to the cluster containing
   *        the database to be used
   * @param aCatalogName is the name of the catalog to be used.
   * @note The catalog name provides a namespace for the tables and
   *       indexes created in any connection from the Ndb object.
   * @param aSchemaName is the name of the schema you 
   *        want to use.
   * @note The schema name provides an additional namespace 
   *       for the tables and indexes created in a given catalog.
   */
  Ndb(Ndb_cluster_connection *ndb_cluster_connection,
      const char* aCatalogName = "", const char* aSchemaName = "def");

  ~Ndb();

#ifndef DOXYGEN_SHOULD_SKIP_INTERNAL
  /**
   * The current catalog name can be fetched by getCatalogName.
   *
   * @return the current catalog name
   */
  const char * getCatalogName() const;

  /**
   * The current catalog name can be set by setCatalogName.
   *
   * @param aCatalogName is the new name of the current catalog
   */
  void setCatalogName(const char * aCatalogName);

  /**
   * The current schema name can be fetched by getSchemaName.
   *
   * @return the current schema name
   */
  const char * getSchemaName() const;

  /**
   * The current schema name can be set by setSchemaName.
   *
   * @param aSchemaName is the new name of the current schema
   */
  void setSchemaName(const char * aSchemaName);
#endif

  /**
   * The current database name can be fetched by getDatabaseName.
   *
   * @return the current database name
   */
  const char * getDatabaseName() const;

  /**
   * The current database name can be set by setDatabaseName.
   *
   * @param aDatabaseName is the new name of the current database
   */
  void setDatabaseName(const char * aDatabaseName);

  /**
   * The current database schema name can be fetched by getDatabaseSchemaName.
   *
   * @return the current database schema name
   */
  const char * getDatabaseSchemaName() const;

  /**
   * The current database schema name can be set by setDatabaseSchemaName.
   *
   * @param aDatabaseSchemaName is the new name of the current database schema
   */
  void setDatabaseSchemaName(const char * aDatabaseSchemaName);

  /**
   * Initializes the Ndb object
   *
   * @param  maxNoOfTransactions 
   *         Maximum number of parallel 
   *         NdbTransaction objects that can be handled by the Ndb object.
   *         Maximum value is 1024.
   *
   * @note each scan or index scan operation uses one extra
   *       NdbTransaction object
   *
   * @return 0 if successful, -1 otherwise.
   */
  int init(int maxNoOfTransactions = 4);

#ifndef DOXYGEN_SHOULD_SKIP_DEPRECATED
  /**
   * Wait for Ndb object to successfully set-up connections to 
   * the NDB kernel. 
   * Starting to use the Ndb object without using this method 
   * gives unspecified behavior. 
   * 
   * @param  timeout  The maximum time we will wait for 
   *                  the initiation process to finish.
   *                  Timeout is expressed in seconds.
   * @return  0: Ndb is ready and timeout has not occurred.<br>
   *          -1: Timeout has expired
   */
  int waitUntilReady(int timeout = 60);
#endif

  /** @} *********************************************************************/

  /** 
   * @name Meta Information
   * @{
   */

  /**
   * Get an object for retrieving or manipulating database schema information 
   *
   * @note this object operates outside any transaction
   *
   * @return Object containing meta information about all tables 
   *         in NDB Cluster.
   */
  class NdbDictionary::Dictionary* getDictionary() const;
  

  /** @} *********************************************************************/

  /** 
   * @name Event subscriptions
   * @{
   */

  /**
   * Create a subcription to an event defined in the database
   *
   * @param eventName
   *        unique identifier of the event
   * @param bufferLength
   *        circular buffer size for storing event data
   *
   * @return Object representing an event, NULL on failure
   */
  NdbEventOperation* createEventOperation(const char* eventName,
					  const int bufferLength);
  /**
   * Drop a subscription to an event
   *
   * @param eventOp
   *        Event operation
   *
   * @return 0 on success
   */
  int dropEventOperation(NdbEventOperation* eventOp);

  /**
   * Wait for an event to occur. Will return as soon as an event
   * is detected on any of the created events.
   *
   * @param aMillisecondNumber
   *        maximum time to wait
   *
   * @return the number of events that has occured, -1 on failure
   */
  int pollEvents(int aMillisecondNumber);

  /** @} *********************************************************************/

  /** 
   * @name Starting and Closing Transactions
   * @{
   */

  /**
   * Start a transaction
   *
   * @note When the transaction is completed it must be closed using
   *       Ndb::closeTransaction or NdbTransaction::close. 
   *       The transaction must be closed independent of its outcome, i.e.
   *       even if there is an error.
   *
   * @param  table    Pointer to table object used for deciding 
   *                  which node to run the Transaction Coordinator on
   * @param  keyData  Pointer to partition key corresponding to
   *                  <var>table</var>
   * @param  keyLen   Length of partition key expressed in bytes
   * 
   * @return NdbTransaction object, or NULL on failure.
   */
  NdbTransaction* startTransaction(const NdbDictionary::Table *table= 0,
				   const char  *keyData = 0, 
				   Uint32       keyLen = 0);

  /**
   * Close a transaction.
   *
   * @note should be called after the transaction has completed, irrespective
   *       of success or failure
   */
#ifndef DOXYGEN_SHOULD_SKIP_INTERNAL
  /**
   * @note It is not allowed to call Ndb::closeTransaction after sending the
   *       transaction asynchronously with either 
   *       Ndb::sendPreparedTransactions or
   *       Ndb::sendPollNdb before the callback method has been called.
   *       (The application should keep track of the number of 
   *       outstanding transactions and wait until all of them 
   *       has completed before calling Ndb::closeTransaction).
   *       If the transaction is not committed it will be aborted.
   */
#endif
  void closeTransaction(NdbTransaction*);

  /** @} *********************************************************************/

#ifndef DOXYGEN_SHOULD_SKIP_INTERNAL
  // to be documented later
  /** 
   * @name Asynchronous Transactions
   * @{
   */

  /**
   * Wait for prepared transactions.
   * Will return as soon as at least 'minNoOfEventsToWakeUp' 
   * of them have completed, or the maximum time given as timeout has passed.
   *
   * @param aMillisecondNumber 
   *        Maximum time to wait for transactions to complete. Polling 
   *        without wait is achieved by setting the timer to zero.
   *        Time is expressed in milliseconds.
   * @param minNoOfEventsToWakeup Minimum number of transactions 
   *            which has to wake up before the poll-call will return.
   *            If minNoOfEventsToWakeup is
   *            set to a value larger than 1 then this is the minimum 
   *            number of transactions that need to complete before the 
   *            poll will return.
   *            Setting it to zero means that one should wait for all
   *            outstanding transactions to return before waking up.
   * @return Number of transactions polled.
   */
  int  pollNdb(int aMillisecondNumber = WAITFOR_RESPONSE_TIMEOUT,
	      int minNoOfEventsToWakeup = 1);

  /**
   * This send method will send all prepared database operations. 
   * The default method is to do it non-force and instead
   * use the adaptive algorithm.  (See Section @ref secAdapt.)
   * The second option is to force the sending and 
   * finally there is the third alternative which is 
   * also non-force but also making sure that the 
   * adaptive algorithm do not notice the send. 
   * In this case the sending will be performed on a 
   * cyclical 10 millisecond event.
   *
   * @param forceSend When operations should be sent to NDB Kernel.
   *                  (See @ref secAdapt.)
   *                  - 0: non-force, adaptive algorithm notices it (default); 
   *                  - 1: force send, adaptive algorithm notices it; 
   *                  - 2: non-force, adaptive algorithm do not notice the send.
   */
  void sendPreparedTransactions(int forceSend = 0);

  /**
   * This is a send-poll variant that first calls 
   * Ndb::sendPreparedTransactions and then Ndb::pollNdb. 
   * It is however somewhat faster than calling the methods 
   * separately, since some mutex-operations are avoided. 
   * See documentation of Ndb::pollNdb and Ndb::sendPreparedTransactions
   * for more details.
   *
   * @param aMillisecondNumber Timeout specifier
   *            Polling without wait is achieved by setting the 
   *            millisecond timer to zero.
   * @param minNoOfEventsToWakeup Minimum number of transactions 
   *            which has to wake up before the poll-call will return.
   *            If minNoOfEventsToWakeup is
   *            set to a value larger than 1 then this is the minimum 
   *            number of transactions that need to complete before the 
   *            poll-call will return.
   *            Setting it to zero means that one should wait for all
   *            outstanding transactions to return before waking up.
   * @param forceSend When operations should be sent to NDB Kernel.
   *                  (See @ref secAdapt.)
   * - 0: non-force, adaptive algorithm notices it (default); 
   * - 1: force send, adaptive algorithm notices it; 
   * - 2: non-force, adaptive algorithm does not notice the send.
   * @return Number of transactions polled.
   */
  int  sendPollNdb(int aMillisecondNumber = WAITFOR_RESPONSE_TIMEOUT,
		   int minNoOfEventsToWakeup = 1,
		   int forceSend = 0);
  /** @} *********************************************************************/
#endif
  
  /** 
   * @name Error Handling
   * @{
   */

  /**
   * Get the NdbError object
   *
   * @note The NdbError object is valid until a new NDB API method is called.
   */
  const NdbError & getNdbError() const;
  
  /**
   * Get a NdbError object for a specific error code
   *
   * The NdbError object is valid until you call a new NDB API method.
   */
  const NdbError & getNdbError(int errorCode);


  /** @} *********************************************************************/

#ifndef DOXYGEN_SHOULD_SKIP_INTERNAL
  /**
   * Get the application node identity.  
   *
   * @return Node id of this application.
   */
  int getNodeId();

  bool usingFullyQualifiedNames();

  /**
   * Different types of tampering with the NDB Cluster.
   * <b>Only for debugging purposes only.</b>
   */
  enum TamperType	{ 
    LockGlbChp = 1,           ///< Lock GCP
    UnlockGlbChp,             ///< Unlock GCP
    CrashNode,                ///< Crash an NDB node
    ReadRestartGCI,           ///< Request the restart GCI id from NDB Cluster
    InsertError               ///< Execute an error in NDB Cluster 
                              ///< (may crash system)
  };

  /**
   * For testing purposes it is possible to tamper with the NDB Cluster
   * (i.e. send a special signal to DBDIH, the NDB distribution handler).
   * <b>This feature should only used for debugging purposes.</b>
   * In a release versions of NDB Cluster,
   * this call always return -1 and does nothing.
   * 
   * @param aAction Action to be taken according to TamperType above
   *
   * @param aNode  Which node the action will be taken
   *              -1:   Master DIH.
   *            0-16:   Nodnumber.
   * @return -1 indicates error, other values have meaning dependent 
   *          on type of tampering.
   */
  int NdbTamper(TamperType aAction, int aNode);  

  /**
   * Return a unique tuple id for a table.  The id sequence is
   * ascending but may contain gaps.
   *
   * @param aTableName table name
   *
   * @param cacheSize number of values to cache in this Ndb object
   *
   * @return tuple id or 0 on error
   */
  Uint64 getAutoIncrementValue(const char* aTableName, 
			       Uint32 cacheSize = 1);
  Uint64 getAutoIncrementValue(const NdbDictionary::Table * aTable, 
			       Uint32 cacheSize = 1);
  Uint64 readAutoIncrementValue(const char* aTableName);
  Uint64 readAutoIncrementValue(const NdbDictionary::Table * aTable);
  bool setAutoIncrementValue(const char* aTableName, Uint64 val, 
			     bool increase = false);
  bool setAutoIncrementValue(const NdbDictionary::Table * aTable, Uint64 val, 
			     bool increase = false);
  Uint64 getTupleIdFromNdb(const char* aTableName, 
			   Uint32 cacheSize = 1000);
  Uint64 getTupleIdFromNdb(Uint32 aTableId, 
			   Uint32 cacheSize = 1000);
  Uint64 readTupleIdFromNdb(Uint32 aTableId);
  bool setTupleIdInNdb(const char* aTableName, Uint64 val, 
		       bool increase);
  bool setTupleIdInNdb(Uint32 aTableId, Uint64 val, bool increase);
  Uint64 opTupleIdOnNdb(Uint32 aTableId, Uint64 opValue, Uint32 op);

  /**
   */
  NdbTransaction* hupp( NdbTransaction* );
  Uint32 getReference() const { return theMyRef;}
#endif

/*****************************************************************************
 *	These are service routines used by the other classes in the NDBAPI.
 ****************************************************************************/
private:
  
  void setup(Ndb_cluster_connection *ndb_cluster_connection,
	     const char* aCatalogName, const char* aSchemaName);

  void connected(Uint32 block_reference);
 

  NdbTransaction*  startTransactionLocal(Uint32 aPrio, Uint32 aFragmentId); 

// Connect the connection object to the Database.
  int NDB_connect(Uint32 tNode);
  NdbTransaction* doConnect(Uint32 nodeId); 
  void    doDisconnect();	 
  
  NdbReceiver*	        getNdbScanRec();// Get a NdbScanReceiver from idle list
  NdbLabel*		getNdbLabel();	// Get a NdbLabel from idle list
  NdbBranch*            getNdbBranch();	// Get a NdbBranch from idle list
  NdbSubroutine*	getNdbSubroutine();// Get a NdbSubroutine from idle
  NdbCall*		getNdbCall();	// Get a NdbCall from idle list
  NdbApiSignal*	        getSignal();	// Get an operation from idle list
  NdbRecAttr*	        getRecAttr();	// Get a receeive attribute object from
					// idle list of the Ndb object.
  NdbOperation* 	getOperation();	// Get an operation from idle list
  NdbIndexScanOperation* getScanOperation(); // Get a scan operation from idle
  NdbIndexOperation* 	getIndexOperation();// Get an index operation from idle

  class NdbGlobalEventBufferHandle* getGlobalEventBufferHandle();
  NdbBlob*              getNdbBlob();// Get a blob handle etc

  void			releaseSignal(NdbApiSignal* anApiSignal);
  void                  releaseSignalsInList(NdbApiSignal** pList);
  void			releaseNdbScanRec(NdbReceiver* aNdbScanRec);
  void			releaseNdbLabel(NdbLabel* anNdbLabel);
  void			releaseNdbBranch(NdbBranch* anNdbBranch);
  void			releaseNdbSubroutine(NdbSubroutine* anNdbSubroutine);
  void			releaseNdbCall(NdbCall* anNdbCall);
  void			releaseRecAttr (NdbRecAttr* aRecAttr);	
  void		 	releaseOperation(NdbOperation* anOperation);	
  void		 	releaseScanOperation(NdbIndexScanOperation*);
  void                  releaseNdbBlob(NdbBlob* aBlob);

  void                  check_send_timeout();
  void                  remove_sent_list(Uint32);
  Uint32                insert_completed_list(NdbTransaction*);
  Uint32                insert_sent_list(NdbTransaction*);

  // Handle a received signal. Used by both
  // synchronous and asynchronous interface
  void handleReceivedSignal(NdbApiSignal* anApiSignal, struct LinearSectionPtr ptr[3]);
  
  // Receive response signals
  int			receiveResponse(int waitTime = WAITFOR_RESPONSE_TIMEOUT);

  int			sendRecSignal(Uint16 aNodeId,
				      Uint32 aWaitState,
				      NdbApiSignal* aSignal,
                                      Uint32 nodeSequence);
  
  // Sets Restart GCI in Ndb object
  void			RestartGCI(int aRestartGCI);

  // Get block number of this NDBAPI object
  int			getBlockNumber();
  
  /****************************************************************************
   *	These are local service routines used by this class.	
   ***************************************************************************/
  
  int			createConIdleList(int aNrOfCon);
  int 		createOpIdleList( int nrOfOp );	

  void	freeOperation();          // Free the first idle operation.
  void	freeScanOperation();      // Free the first idle scan operation.
  void	freeIndexOperation();     // Free the first idle index operation.
  void	freeNdbCon();	// Free the first idle connection.
  void	freeSignal();	// Free the first idle signal	
  void	freeRecAttr();	// Free the first idle receive attr obj	
  void	freeNdbLabel();	// Free the first idle NdbLabel obj
  void	freeNdbBranch();// Free the first idle NdbBranch obj
  void	freeNdbSubroutine();// Free the first idle NdbSubroutine obj
  void	freeNdbCall();	    // Free the first idle NdbCall obj
  void	freeNdbScanRec();   // Free the first idle NdbScanRec obj
  void  freeNdbBlob();      // Free the first etc

  NdbTransaction* getNdbCon();	// Get a connection from idle list
  
  /**
   * Get a connected NdbTransaction to nodeId
   *   Returns NULL if none found
   */
  NdbTransaction* getConnectedNdbTransaction(Uint32 nodeId);

  // Release and disconnect from DBTC a connection
  // and seize it to theConIdleList
  void	releaseConnectToNdb (NdbTransaction*);

  // Release a connection to idle list
  void 	releaseNdbCon (NdbTransaction*);
  
  int	checkInitState();		// Check that we are initialized
  void	report_node_failure(Uint32 node_id);           // Report Failed node
  void	report_node_failure_completed(Uint32 node_id); // Report Failed node(NF comp.)

  void	checkFailedNode();		// Check for failed nodes

  int   NDB_connect();     // Perform connect towards NDB Kernel

  // Release arrays of NdbTransaction pointers
  void  releaseTransactionArrays();     

  Uint32  pollCompleted(NdbTransaction** aCopyArray);
  void    sendPrepTrans(int forceSend);
  void    reportCallback(NdbTransaction** aCopyArray, Uint32 aNoOfComplTrans);
  void    waitCompletedTransactions(int milliSecs, int noOfEventsToWaitFor);
  void    completedTransaction(NdbTransaction* aTransaction);
  void    completedScanTransaction(NdbTransaction* aTransaction);

  void    abortTransactionsAfterNodeFailure(Uint16 aNodeId);

  static
  const char * externalizeTableName(const char * internalTableName, bool fullyQualifiedNames);
  const char * externalizeTableName(const char * internalTableName);
  const char * internalizeTableName(const char * externalTableName);

  static
  const char * externalizeIndexName(const char * internalIndexName, bool fullyQualifiedNames);
  const char * externalizeIndexName(const char * internalIndexName);
  const char * internalizeIndexName(const NdbTableImpl * table,
				    const char * externalIndexName);

  static
  const BaseString getDatabaseFromInternalName(const char * internalName);
  static 
  const BaseString getSchemaFromInternalName(const char * internalName);

  void*              int2void     (Uint32 val);
  NdbReceiver*       void2rec     (void* val);
  NdbTransaction*     void2con     (void* val);
  NdbOperation*      void2rec_op  (void* val);
  NdbIndexOperation* void2rec_iop (void* val);

/******************************************************************************
 *	These are the private variables in this class.	
 *****************************************************************************/
  NdbTransaction**       thePreparedTransactionsArray;
  NdbTransaction**       theSentTransactionsArray;
  NdbTransaction**       theCompletedTransactionsArray;

  Uint32                theNoOfPreparedTransactions;
  Uint32                theNoOfSentTransactions;
  Uint32                theNoOfCompletedTransactions;
  Uint32                theNoOfAllocatedTransactions;
  Uint32                theMaxNoOfTransactions;
  Uint32                theMinNoOfEventsToWakeUp;

  Uint32                theNextConnectNode;

  bool fullyQualifiedNames;

  // Ndb database name.
  char                  theDataBase[NDB_MAX_DATABASE_NAME_SIZE];
  // Ndb database schema name.  
  char                  theDataBaseSchema[NDB_MAX_SCHEMA_NAME_SIZE];
  char                  prefixName[NDB_MAX_INTERNAL_TABLE_LENGTH];
  char *                prefixEnd;		

  class NdbImpl * theImpl;
  class NdbDictionaryImpl* theDictionary;
  class NdbGlobalEventBufferHandle* theGlobalEventBufferHandle;

  NdbTransaction*	theConIdleList;	// First connection in idle list.

  NdbOperation*		theOpIdleList;	// First operation in the idle list. 

  NdbIndexScanOperation* theScanOpIdleList;	// First scan operation in the idle list. 
  NdbIndexOperation*	theIndexOpIdleList;	// First index operation in the idle list. 
  NdbTransaction*	theTransactionList;
  NdbTransaction**      theConnectionArray;
  NdbRecAttr*		theRecAttrIdleList;  
  NdbApiSignal*		theSignalIdleList;   // First signal in idlelist.
  NdbLabel*		theLabelList;	     // First label descriptor in list
  NdbBranch*		theBranchList;	     // First branch descriptor in list
  NdbSubroutine*	theSubroutineList;   // First subroutine descriptor in
  NdbCall*		theCallList;	     // First call descriptor in list
  NdbReceiver*          theScanList;
  NdbBlob*              theNdbBlobIdleList;

  Uint32   theMyRef;        // My block reference  
  Uint32   theNode;         // The node number of our node
  
  Uint64               the_last_check_time;
  Uint64               theFirstTransId;
  
  // The tupleId is retreived from DB the 
  // tupleId is unique for each tableid. 
  Uint64               theFirstTupleId[2048]; 
  Uint64               theLastTupleId[2048];           

  Uint32		theRestartGCI;	// the Restart GCI used by DIHNDBTAMPER
  
  NdbError              theError;

  Int32        	        theNdbBlockNumber;

  enum InitType {
    NotConstructed,
    NotInitialised,
    StartingInit,
    Initialised,
    InitConfigError
  } theInitState;

  NdbApiSignal* theCommitAckSignal;


#ifdef POORMANSPURIFY
  int cfreeSignals;
  int cnewSignals;
  int cgetSignals;
  int creleaseSignals;
#endif

  static void executeMessage(void*, NdbApiSignal *, 
			     struct LinearSectionPtr ptr[3]);
  static void statusMessage(void*, Uint32, bool, bool);
#ifdef VM_TRACE
  void printState(const char* fmt, ...);
#endif
};

#endif