com.goldencode.p2j.persist.sequence

Class MariaDbSequenceHandler

java.lang.Object

com.goldencode.p2j.persist.sequence.SequenceHandler

com.goldencode.p2j.persist.sequence.MariaDbSequenceHandler

public class MariaDbSequenceHandler
extends SequenceHandler

MariaDb implementation of sequences using a native SQL sequence primitives queries. Each primitive tries to execute exactly one database query (except NEXT-VALUE, where the output is checked to match the P4GL jump-to INITIAL value instead of MIN-VALUE).

Field Summary

Fields

Modifier and Type	Field and Description
private static CentralLogger	LOG Central Logger.
private java.util.HashMap<java.lang.String,java.util.Set<java.lang.String>>	sequences The list of sequences grouped by databases.

Constructor Summary

Constructors

Constructor and Description
MariaDbSequenceHandler(java.lang.String ldbName) The only constructor takes the name of the database as argument.

Method Summary

Modifier and Type	Method and Description
private static java.lang.Object	executeSQL(java.lang.String sqlStmt, Database db, boolean select, java.lang.Object... params) Execute a SQL statement and optionally return the result as a single value.
protected boolean	safeContains(java.lang.String seqName, java.lang.String ldbName) Test whether the database contains a sequence.
protected int64	safeGetCurrentValue(java.lang.String seqName, java.lang.String ldbName) Queries the current value of a sequence.
protected int64	safeGetNextValue(java.lang.String seqName, java.lang.String ldbName) Computes and returns the next value of a sequence.
protected void	safeSetValue(java.lang.String seqName, java.lang.String ldbName, long newVal) Initialize (reset) the current value of a sequence.

Methods inherited from class com.goldencode.p2j.persist.sequence.SequenceHandler

contains, getCurrentValue, getNextValue, getResultValue, setValue

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

LOG

private static final CentralLogger LOG

Central Logger.

sequences

private java.util.HashMap<java.lang.String,java.util.Set<java.lang.String>> sequences

The list of sequences grouped by databases. It uses lazy initialization.

Constructor Detail

MariaDbSequenceHandler

public MariaDbSequenceHandler(java.lang.String ldbName)

The only constructor takes the name of the database as argument. It is passed on to super class.

Parameters:

ldbName - The database logical name on which this handler will work with.

Method Detail

safeGetCurrentValue

protected int64 safeGetCurrentValue(java.lang.String seqName,
                                    java.lang.String ldbName)

Queries the current value of a sequence.

This method should be called only in a safe environment, where the database-level lock for access to sequences has already been acquired.

Overrides:

safeGetCurrentValue in class SequenceHandler

Parameters:

seqName - The name of the sequence.

ldbName - The database to which the sequence belongs to. It is assumed it is not null and valid.

Returns:

the current value of the sequence

safeGetNextValue

protected int64 safeGetNextValue(java.lang.String seqName,
                                 java.lang.String ldbName)

Computes and returns the next value of a sequence.

This method should be called only in a safe environment, where the database-level lock for access to sequences has already been acquired.

Overrides:

safeGetNextValue in class SequenceHandler

Parameters:

seqName - The name of the sequence.

ldbName - The database to which the sequence belongs to. It is assumed it is not null and valid.

Returns:

the next value of the sequence or unknown value (?) if sequence/database not found or the sequence is not cycling and has passed the maximum/minimum value.

safeSetValue

protected void safeSetValue(java.lang.String seqName,
                            java.lang.String ldbName,
                            long newVal)

Initialize (reset) the current value of a sequence.

This method should be called only in a safe environment, where the database-level lock for access to sequences has already been acquired.

Overrides:

safeSetValue in class SequenceHandler

Parameters:

seqName - The name of the sequence.

ldbName - The database to which the sequence belongs to. It is assumed it is not null and valid.

newVal - The value the sequence will be reset to.

safeContains

protected boolean safeContains(java.lang.String seqName,
                               java.lang.String ldbName)

Test whether the database contains a sequence. This is useful to identify the correct database/sequences when a 4GL static function / statement is called without the database parameter.

This method should be called only in a safe environment, where the database-level lock for access to sequences has already been acquired.

Overrides:

safeContains in class SequenceHandler

Parameters:

seqName - The name of the sequence.

ldbName - The database to which the sequence belongs to. If is null then the first connected database is assumed.

Returns:

true if the sequence is defined in the database

executeSQL

private static java.lang.Object executeSQL(java.lang.String sqlStmt,
                                           Database db,
                                           boolean select,
                                           java.lang.Object... params)

Execute a SQL statement and optionally return the result as a single value.

Parameters:

sqlStmt - The SQL statement to be executed.

db - The Database on which the statement will be executed.

select - Flags a SELECT statement. The statement will be executed as a query and the first result will be returned as unique value.

params - An optional set of parameters for the statement.

Returns:

In case of a SELECT statement the value is the unique (first) column in first row, or null is the query provided an empty result set. In case of not SELECT statements, the result is always null.