weblogic.cluster.singleton
Class QueryHelper

java.lang.Object
  weblogic.cluster.singleton.QueryHelper

Direct Known Subclasses:

QueryHelperImpl

public abstract class QueryHelper
extends Object

Helper class for ClusterMaster to determine servers that are unresponsive and to find lease owners. Queries for lease management. Each lease has an associated timeout which is calculated as (SYSDATE - TIMEOUT). TIMEOUT is initially caclulated as an absolute time in the future (ie. SYSDATE + interval), without renewal TIMEOUT will eventually be in the past and SYSDATE - TIMEOUT will become positive.

TIME_AS_FRACTION_OF_DAY

public static String TIME_AS_FRACTION_OF_DAY

QueryHelper

public QueryHelper(String tableName,
                   String domainName,
                   String clusterName,
                   int dbType)

QueryHelper

public QueryHelper()

init

protected void init(String tableName,
                    String domainName,
                    String clusterName,
                    int dbType)

addToDate

protected abstract String addToDate(String date,
                                    int seconds)

Returns an sql snippet that adds the specifed number of seconds to the date value.

Parameters:

date - date variable to add to

seconds - number of seconds to add to column

Returns:

an sql snippet

compareDates

protected abstract String compareDates(String date1,
                                       String date2)

Returns an sql snippet that compares the two specified dates. The query should return true if date1 is later than date2.

Parameters:

date1 -

date2 -

Returns:

an sql snippet

compareDates

protected abstract String compareDates(String date1,
                                       String date2,
                                       boolean includeEquality)

Returns an sql snippet that compares the two specified dates. The query should return true if date1 is later than date2.

Parameters:

date1 -

date2 -

includeEquality -

getTimeFunction

protected abstract String getTimeFunction()

Returns a query that returns the current time & date, down to at least seconds precision.

Returns:

an sql snippet

getDBType

protected int getDBType()

getLeaseOwnerQuery

public String getLeaseOwnerQuery(String leaseName)

Returns a query that returns the owner of the provided lease

Parameters:

leaseName - name of lease

Returns:

a query string

getPreviousLeaseOwnerQuery

public String getPreviousLeaseOwnerQuery(String leaseName)

Returns the current/last owner of the provided lease, regardless of whether it has expired or not.

Parameters:

leaseName - name of lease

Returns:

a query string

getAcquireLeaseQuery

public String getAcquireLeaseQuery(String leaseName,
                                   String owner)

Returns a query that tries to delete any timed-out leases associated with this name.

Parameters:

leaseName - name of lease

owner - server who is the owner as a transient identity string

Returns:

a query string

getAssumeLeaseQuery

public String getAssumeLeaseQuery(String leaseName,
                                  String owner,
                                  int leaseTimeout)

Returns a query that tries to insert a new lease into the database with the given lease name and timeout period.

Parameters:

leaseName - name of lease

owner - server who is the owner as a transient identity string

leaseTimeout - period after which the lease will timeout in seconds from now

Returns:

a query string

getRenewLeaseQuery

public String getRenewLeaseQuery(String leaseName,
                                 String owner,
                                 int leaseTimeout)

Returns a query that updates the provided lease to be valid until 'timeoutPeriod' seconds pass

Parameters:

leaseName - name of lease

owner - server who is the owner as a transient identity string

leaseTimeout - period after which the lease will expire in seconds from now

Returns:

a query string

getRenewLeasesQuery

public String getRenewLeasesQuery(String owner,
                                  Set leaseNames,
                                  int leaseTimeout)

Returns a query that updates the provided leases to be valid until 'timeoutPeriod' seconds pass

Parameters:

owner - server who is the owner as a transient identity string

leaseNames - name of leases

leaseTimeout - period after which the lease will expire in seconds from now

Returns:

a query string

getRenewAllLeasesQuery

public String getRenewAllLeasesQuery(String owner,
                                     int leaseTimeout)

Returns a query that updates all the leases in database owned by 'owner' to be valid until 'timeoutPeriod' seconds pass.

Parameters:

owner - server who is the owner of the leases as a transient identity string

leaseTimeout - period after which the lease will expire in seconds from now

Returns:

a query string

getAbdicateLeaseQuery

public String getAbdicateLeaseQuery(String leaseName,
                                    String owner)

Returns a query that removes lease from database, regardless of if it is expired or not. Only works for leases held by 'owner'.

Parameters:

leaseName - name of lease

owner - server who is the owner as a transient identity string

Returns:

a query string

getUnresponsiveMigratableServersQuery

public String getUnresponsiveMigratableServersQuery(int gracePeriod)

Returns a query that returns a list of server names that failed to renew their lease. This query is used to determine what servers should be restarted, so it includes the grace period in its calculations.

Parameters:

gracePeriod - amount of time to wait after a lease expires before the server is migrated, in seconds

Returns:

a query string

getInsertMachineQuery

public String getInsertMachineQuery(String serverName,
                                    String hostMachine,
                                    String machineTableName)

Returns a query that associates a server with a machine in the given table

Parameters:

serverName - name of server

hostMachine - name of the machine

Returns:

a query string

getDeleteMachineQuery

public String getDeleteMachineQuery(String serverName,
                                    String machineTableName)

Returns a query that disassociates a server from a machine in the given table

Parameters:

serverName - name of server

machineTableName - table to delete from

Returns:

a query string

getRetrieveMachineQuery

public String getRetrieveMachineQuery(String serverName,
                                      String machineTableName)

Returns a query that finds the machine associated with the given server name

Parameters:

serverName - name of server

machineTableName - table to perform the lookup in

Returns:

a query string