Package org.h2.mvstore.tx

Class Transaction

  • public final class Transaction
extends java.lang.Object
    A transaction.

    • Field Summary

      Fields 
      Modifier and Type Field Description
      static int STATUS_CLOSED
      The status of a closed transaction (committed or rolled back).
      static int STATUS_COMMITTED
      The status of a transaction that has been logically committed or rather marked as committed, because it might be still listed among prepared, if it was prepared for commit.
      static int STATUS_OPEN
      The status of an open transaction.
      static int STATUS_PREPARED
      The status of a prepared transaction.

    • Field Detail

      • STATUS_CLOSED

        public static final int STATUS_CLOSED
        The status of a closed transaction (committed or rolled back).
        See Also:
        Constant Field Values

      • STATUS_OPEN

        public static final int STATUS_OPEN
        The status of an open transaction.
        See Also:
        Constant Field Values

      • STATUS_PREPARED

        public static final int STATUS_PREPARED
        The status of a prepared transaction.
        See Also:
        Constant Field Values

      • STATUS_COMMITTED

        public static final int STATUS_COMMITTED
        The status of a transaction that has been logically committed or rather marked as committed, because it might be still listed among prepared, if it was prepared for commit. Undo log entries might still exist for it and not all the transaction changes within maps are re-written as committed yet. Nevertheless, those changes should be already viewed by other transactions as committed. This transaction's id can not be re-used until all of the above is completed and transaction is closed. A transactions can be observed in this state when the store was closed while the transaction was not closed yet. When opening a store, such transactions will automatically be processed and closed as committed.
        See Also:
        Constant Field Values

    • Method Detail

      • getId

        public int getId()

      • getSequenceNum

        public long getSequenceNum()

      • getStatus

        public int getStatus()

      • hasChanges

        public boolean hasChanges()
        Determine if any database changes were made as part of this transaction.
        Returns:
        true if there are changes to commit, false otherwise

      • setName

        public void setName​(java.lang.String name)

      • getName

        public java.lang.String getName()

      • getBlockerId

        public int getBlockerId()

      • setSavepoint

        public long setSavepoint()
        Create a new savepoint.
        Returns:
        the savepoint id

      • hasStatementDependencies

        public boolean hasStatementDependencies()
        Returns whether statement dependencies are currently set.
        Returns:
        whether statement dependencies are currently set

      • getIsolationLevel

        public IsolationLevel getIsolationLevel()
        Returns the isolation level of this transaction.
        Returns:
        the isolation level of this transaction

      • allowNonRepeatableRead

        public boolean allowNonRepeatableRead()
        Whether this transaction has isolation level READ_COMMITTED or below.
        Returns:
        true if isolation level is READ_COMMITTED or READ_UNCOMMITTED

      • markStatementStart

        public void markStatementStart​(java.util.HashSet<MVMap<java.lang.Object,​VersionedValue<java.lang.Object>>> maps)
        Mark an entry into a new SQL statement execution within this transaction.
        Parameters:
        maps - set of maps used by transaction or statement is about to be executed

      • markStatementEnd

        public void markStatementEnd()
        Mark an exit from SQL statement execution within this transaction.

      • openMap

        public <K,​V> TransactionMap<K,​V> openMap​(java.lang.String name)
        Open a data map.
        Type Parameters:
        K - the key type
        V - the value type
        Parameters:
        name - the name of the map
        Returns:
        the transaction map

      • openMap

        public <K,​V> TransactionMap<K,​V> openMap​(java.lang.String name,
                                                     DataType<K> keyType,
                                                     DataType<V> valueType)
        Open the map to store the data.
        Type Parameters:
        K - the key type
        V - the value type
        Parameters:
        name - the name of the map
        keyType - the key data type
        valueType - the value data type
        Returns:
        the transaction map

      • openMapX

        public <K,​V> TransactionMap<K,​V> openMapX​(MVMap<K,​VersionedValue<V>> map)
        Open the transactional version of the given map.
        Type Parameters:
        K - the key type
        V - the value type
        Parameters:
        map - the base map
        Returns:
        the transactional map

      • prepare

        public void prepare()
        Prepare the transaction. Afterward, the transaction can only be committed or completely rolled back.

      • commit

        public void commit()
        Commit the transaction. Afterward, this transaction is closed.

      • rollbackToSavepoint

        public void rollbackToSavepoint​(long savepointId)
        Roll back to the given savepoint. This is only allowed if the transaction is open.
        Parameters:
        savepointId - the savepoint id

      • rollback

        public void rollback()
        Roll the transaction back. Afterward, this transaction is closed.

      • getChanges

        public java.util.Iterator<TransactionStore.Change> getChanges​(long savepointId)
        Get the list of changes, starting with the latest change, up to the given savepoint (in reverse order than they occurred). The value of the change is the value before the change was applied.
        Parameters:
        savepointId - the savepoint id, 0 meaning the beginning of the transaction
        Returns:
        the changes

      • setTimeoutMillis

        public void setTimeoutMillis​(int timeoutMillis)
        Sets the new lock timeout.
        Parameters:
        timeoutMillis - the new lock timeout in milliseconds

      • waitFor

        public boolean waitFor​(Transaction toWaitFor,
                       java.lang.String mapName,
                       java.lang.Object key,
                       int timeoutMillis)
        Make this transaction to wait for the specified transaction to be closed, because both of them try to modify the same map entry.
        Parameters:
        toWaitFor - transaction to wait for
        mapName - name of the map containing blocking entry
        key - of the blocking entry
        timeoutMillis - timeout in milliseconds, -1 for default
        Returns:
        true if other transaction was closed and this one can proceed, false if timed out

      • removeMap

        public <K,​V> void removeMap​(TransactionMap<K,​V> map)
        Remove the map.
        Type Parameters:
        K - the key type
        V - the value type
        Parameters:
        map - the map

      • toString

        public java.lang.String toString()
        Overrides:
        toString in class java.lang.Object