Class RowLocking2

All Implemented Interfaces:
LockingPolicy
Direct Known Subclasses:
RowLocking1, RowLocking2nohold

public class RowLocking2 extends RowLockingRR
A locking policy that implements row level locking with isolation degree 2. The approach is to place all "write" container and row locks on the transaction group lock list. Locks on this group will last until end of transaction. All "read" container and row locks will be placed on a group list, key'd by the ContainerId of the lock. Locks on this list will either be released explicitly by the caller, or will be released as a group when the unlockContainer() call is made. Note that write operations extend from the RowLocking3 implementations.
See Also:
  • Field Details

  • Constructor Details

  • Method Details

    • lockContainer

      public boolean lockContainer(Transaction t, ContainerHandle container, boolean waitForLock, boolean forUpdate) throws StandardException
      Obtain container level intent lock.

      This implementation of row locking is 2 level, ie. table and row locking. It will interact correctly with tables opened with ContainerLocking3 locking mode.

      Updater's will get table level IX locks, and X row locks.

      Reader's will get table level IS locks, and S row locks.

      Read locks are put in a separate "group" from the transaction, so that when the container is closed it can release these read locks.

      Specified by:
      lockContainer in interface LockingPolicy
      Overrides:
      lockContainer in class RowLocking3
      Parameters:
      t - Transaction to associate lock with.
      container - Container to lock.
      waitForLock - Should lock request wait until granted?
      forUpdate - Should container be locked for update, or read?
      Returns:
      true if the lock was obtained, false if it wasn't. False should only be returned if the waitForLock policy was set to "false," and the lock was unavailable.
      Throws:
      StandardException - Standard exception policy.
      See Also:
    • lockRecordForRead

      public boolean lockRecordForRead(Transaction t, ContainerHandle container_handle, RecordHandle record, boolean waitForLock, boolean forUpdate) throws StandardException
      Obtain lock on record being read.

      Assumes that a table level IS has been acquired. Will acquire a Shared or Update lock on the row, depending on the "forUpdate" parameter.

      Read lock will be placed on separate group from transaction.

      Specified by:
      lockRecordForRead in interface LockingPolicy
      Overrides:
      lockRecordForRead in class RowLocking3
      Parameters:
      t - The transaction to associate the lock with.
      container_handle - Open Container used to get record. Will be used to row locks by the container they belong to.
      record - The record to be locked.
      waitForLock - Should lock request wait until granted?
      forUpdate - Whether to open for read or write access.
      Returns:
      true if the lock was granted, false if waitForLock was false and the lock could not be granted.
      Throws:
      StandardException - Standard exception policy.
      See Also:
    • unlockRecordAfterRead

      public void unlockRecordAfterRead(Transaction t, ContainerHandle container_handle, RecordHandle record, boolean forUpdate, boolean row_qualified) throws StandardException
      Description copied from class: RowLockingRR
      Unlock a record after it has been locked for read.

      In repeatable read only unlock records which "did not qualify". For example in a query like "select * from foo where a = 1" on a table with no index it is only necessary to hold locks on rows where a=1, but in the process of finding those rows the system will get locks on other rows to verify they are committed before applying the qualifier. Those locks can be released under repeatable read isolation.

      Specified by:
      unlockRecordAfterRead in interface LockingPolicy
      Overrides:
      unlockRecordAfterRead in class RowLockingRR
      Throws:
      StandardException - Standard exception policy.
      See Also:
    • unlockContainer

      public void unlockContainer(Transaction t, ContainerHandle container_handle)
      Unlock read locks.

      In Cursor stability release all read locks obtained. unlockContainer() will be called when the container is closed.

      Specified by:
      unlockContainer in interface LockingPolicy
      Overrides:
      unlockContainer in class NoLocking
      Parameters:
      t - The transaction to associate the lock with.
      container_handle - Container to unlock.
      See Also: