Examples of org.apache.derby.iapi.store.raw.Page

org.apache.derby.iapi.store.raw.Page
A Page contains an ordered set of records which are the stored form of rows. A record is a stream of bytes created from a row array. The record contains one or more fields, fields have a one to one correlation with the DataValueDescriptor's contained within a row array.
A Page represents exclusive access to a data page within a container. Exclusive access is released by calling the unlatch() method, once that occurs the caller must no longer use the Page reference.
Several of the methods in Page take a RecordHandle as an argument. RecordHandles are obtained from a Page, while holding exclusive access of Page or a from a previous exclusive access of a Page representing the same data page. All RecordHandle's used as arguments to methods (with the exception of recordExists()) must be valid for the current state of the page. If they are not valid then the method will throw an exception. A caller can ensure that a record handle is valid by:
- Obtaining the handle during this exclusive access of this page
- Checking the record still exists with the method recordExists()
- Not using a handle after a deleteAtSlot().
Several of the methods in Page take a slot number as an argument. A slot always correspond to a record, which may be deleted or undeleted.
MT - Latched - In general every method requires the page to be latched.
Latching
All page methods which are not valid for a latched page throw an exception if the page is not latched. [@exception clauses on all the methods should be updated to reflect this].
Aux Objects
The page cache will manage a client object along with the page as long as it remains in cache. This object is called the "aux object". The aux object is associated with the page with setAuxObject(), and can be retreived later with getAuxObject(). The aux object will remain valid as long as the page is latched, but callers cannot assume that an aux object will ever stick around once the page is unlatched. However, the page manager promises to call pageBeingEvicted() once before clearing the aux reference from the page. @see Object @see ContainerHandle @see RecordHandle @see AuxObject

     */
    void savePositionAndReleasePage(DataValueDescriptor[] partialKey,
                                    int[] vcols)
            throws StandardException {


        final Page page = scan_position.current_leaf.getPage();


        if (SanityManager.DEBUG) {
            SanityManager.ASSERT(page.isLatched(), "Page is not latched");
            SanityManager.ASSERT(scan_position.current_positionKey == null,
                                 "Scan position already saved");


            if (partialKey == null) {
                SanityManager.ASSERT(vcols == null);
            }
            if (vcols != null) {
                SanityManager.ASSERT(partialKey != null);
                SanityManager.ASSERT(vcols.length <= partialKey.length);
            }
        }


        try {
            DataValueDescriptor[] fullKey = scan_position.getKeyTemplate();


            FetchDescriptor fetchDescriptor = null;
            boolean haveAllColumns = false;
            if (partialKey != null) {
                int copiedCols = 0;
                final int partialKeyLength =
                        (vcols == null) ? partialKey.length : vcols.length;
                for (int i = 0; i < partialKeyLength; i++) {
                    if (vcols == null || vcols[i] != 0) {
                        fullKey[i].setValue(partialKey[i]);
                        copiedCols++;
                    }
                }
                if (copiedCols < fullKey.length) {
                    fetchDescriptor =
                            scan_position.getFetchDescriptorForSaveKey(
                            vcols, fullKey.length);
                } else {
                    haveAllColumns = true;
                }
            }


            if (!haveAllColumns) {
                RecordHandle rh = page.fetchFromSlot(
                        (RecordHandle) null,
                        scan_position.current_slot,
                        fullKey,
                        fetchDescriptor,
                        true);


                if (SanityManager.DEBUG) {
                    SanityManager.ASSERT(rh != null, "Row not found");
                }
            }


            scan_position.current_positionKey = fullKey;
            // Don't null out current_rh, we might be able to use it later if
            // no rows are moved off the page.
            //scan_position.current_rh = null;
            scan_position.versionWhenSaved = page.getPageVersion();
            scan_position.current_slot = Page.INVALID_SLOT_NUMBER;


        } finally {
            scan_position.current_leaf.release();
            scan_position.current_leaf = null;

View Full Code Here

  public void restoreLoggedRow(
    Object[]   row, 
    LimitObjectInput        in)
    throws StandardException, IOException
  {
    Page p = null;


    try {
      // the optional data is written by the page in the same format it
      // stores record on the page, 
      // only a page knows how to restore a logged row back to a storable row
      // first get the page where the insert went even though the row may no
      // longer be there
      p = getContainer().getPage(getPageId().getPageNumber());




      ((BasePage)p).restoreRecordFromStream(in, row);


    } finally {


      if (p != null) {
        p.unlatch();
        p = null;
      }
    }
  }

View Full Code Here

            SanityManager.ASSERT(container != null, 
                "ControlRow.Get() is being called on a closed container.");
        }


    // Get the page, waiting if necessary.  The page is returned latched.
    Page page = container.getPage(pageNumber);


        if (SanityManager.DEBUG)
        {
      if (page == null)
              SanityManager.THROWASSERT(

View Full Code Here

    long            pageNumber)
    throws StandardException
  {
    // Try to get the page without waiting.  If we would have
    // to wait, return null.
    Page page = open_btree.container.getUserPageNoWait(pageNumber);
    if (page == null)
      return null; 


    // Got the page without waiting.  Return the corresponding
    // control row.

View Full Code Here

    private static LeafControlRow allocate(
    OpenBTree   btree, 
    ControlRow  parent)
        throws StandardException
    {
        Page      page      = btree.container.addPage();


        // Create a control row for the new page.
        LeafControlRow control_row = 
            new LeafControlRow(btree, page, parent, false);


        // Insert the control row on the page, in the first slot on the page.
        // This operation is only done as part of a new tree or split, which
        // which both will be undone physically so no logical undo record is
        // needed.
    byte insertFlag = Page.INSERT_INITIAL;
    insertFlag |= Page.INSERT_DEFAULT;
        RecordHandle rh = 
            page.insertAtSlot(Page.FIRST_SLOT_NUMBER,
                control_row.getRow(),
                (FormatableBitSet) null, 
                (LogicalUndo) null, insertFlag,
        AccessFactoryGlobals.BTREE_OVERFLOW_THRESHOLD);


        if (SanityManager.DEBUG)
        {
            RecordHandle    rh2 = null;


            rh2 = page.fetchFromSlot(
                    (RecordHandle) null, page.FIRST_SLOT_NUMBER, 
                    new DataValueDescriptor[0], (FetchDescriptor) null, true); 


            SanityManager.ASSERT(rh.getId() == rh2.getId() &&
                                 rh.getPageNumber() == rh2.getPageNumber());

View Full Code Here

     */
    public static void initEmptyBtree(
    OpenBTree   open_btree)
        throws StandardException
    {
        Page page = 
            open_btree.container.getPage(ContainerHandle.FIRST_PAGE_NUMBER);


        // create a leaf control row for root page of a single page index //
        LeafControlRow control_row =
            new LeafControlRow(open_btree, page, null, true);


    byte insertFlag = Page.INSERT_INITIAL;
    insertFlag |= Page.INSERT_DEFAULT;
        RecordHandle rh = 
            page.insertAtSlot(
                Page.FIRST_SLOT_NUMBER,
                control_row.getRow(),
                (FormatableBitSet) null,
                (LogicalUndo) null, insertFlag,
        AccessFactoryGlobals.BTREE_OVERFLOW_THRESHOLD);


        if (SanityManager.DEBUG)
        {
            RecordHandle    rh2 = null;


            rh2 = page.fetchFromSlot(
                    (RecordHandle) null, 
                    Page.FIRST_SLOT_NUMBER, 
                    new DataValueDescriptor[0], (FetchDescriptor) null, true); 


            SanityManager.ASSERT(rh.getId() == rh2.getId() &&
                                 rh.getPageNumber() == rh2.getPageNumber());
        }


        if (SanityManager.DEBUG)
        {
            if (SanityManager.DEBUG_ON("enableBtreeConsistencyCheck"))
            {
                control_row.checkConsistency(
                    open_btree, (ControlRow) null, true);
            }
        }


        page.unlatch();


        return;
    }

View Full Code Here

  */
  public void restoreLoggedRow(Object[] row, LimitObjectInput in)
    throws StandardException, IOException


  {
    Page p = null;


    try {
      // the optional data is written by the page in the same format it
      // stores record on the page, 
      // only a page knows how to restore a logged row back to a storable row
      // first get the page where the insert went even though the row may no
      // longer be there
      p = getContainer().getPage(getPageId().getPageNumber());


      ((BasePage)p).restoreRecordFromStream(in, row);


    } finally {


      if (p != null) {
        p.unlatch();
        p = null;
      }
    }
  }

View Full Code Here


            DataValueDescriptor[] row = 
                runtime_mem.get_row_for_export(getRawTran());


            // Print pages of the heap.
            Page page = container.getFirstPage();


            while (page != null)
            {
                SanityManager.DEBUG_PRINT(
                    "p_heap", ConglomerateUtil.debugPage(page, 0, false, row));


                long pageid = page.getPageNumber();
                page.unlatch();
                page = container.getNextPage(pageid);
            }
        }


        return;

View Full Code Here


    // create the first alloc page and the first user page, 
    // if this fails for any reason the transaction
    // will roll back and the container will be dropped (removed)
    ContainerHandle containerHdl = null;
    Page            firstPage    = null;


    try 
        {
      // if opening a temporary container with IS_KEPT flag set,
      // make sure to open it with IS_KEPT too.
      if (tmpContainer && 
        ((temporaryFlag & TransactionController.IS_KEPT) == 
                     TransactionController.IS_KEPT)) 
            {


        mode |= ContainerHandle.MODE_TEMP_IS_KEPT;
      }


      // open no-locking as we already have the container locked
      containerHdl = 
                t.openContainer(
                    identity, null, (ContainerHandle.MODE_FORUPDATE | mode)); 


      // we just added it, containerHdl should not be null
            if (SanityManager.DEBUG)
                SanityManager.ASSERT(containerHdl != null);


      if (!tmpContainer) 
            {
        // make it persistent (in concept if not in reality)
        RawContainerHandle rch = (RawContainerHandle)containerHdl;


        ContainerOperation lop = 
          new ContainerOperation(rch, ContainerOperation.CREATE);


        // mark the container as pre-dirtied so that if a checkpoint
        // happens after the log record is sent to the log stream, the
        // cache cleaning will wait for this change.
        rch.preDirty(true);
        try
        {
          t.logAndDo(lop);


          // flush the log to reduce the window between where
          // the container is created & synced and the log record
          // for it makes it to disk. If we fail in this
          // window we will leave a stranded container file.
          flush(t.getLastLogInstant());
        }
        finally
        {
          // in case logAndDo fail, make sure the container is not
          // stuck in preDirty state.
          rch.preDirty(false);
        }
      }


      firstPage = containerHdl.addPage();


    } 
        finally 
        {


      if (firstPage != null) 
            {
        firstPage.unlatch();
        firstPage = null;
      }
      
      containerCache.release(container);

View Full Code Here

    FormatableBitSet                 validColumns)
        throws StandardException
    {
        repositionScanForUpateOper();


        Page page = scan_position.current_page;
        int slot = scan_position.current_slot;


        if (SanityManager.DEBUG) {
            // DERBY-2197: Previously, we would try to get an exclusive row
            // lock here when the container was opened in row locking mode. In
            // most cases, the container is not opened in row locking mode. If
            // it is, and the open conglomerate uses update locks,
            // repositionScanForUpateOper() has already obtained an exclusive
            // row lock. We don't expect this method to be called unless these
            // conditions are satisfied, so now we just assert that no row
            // locking is required at this point.
            SanityManager.ASSERT(
                ((open_conglom.getContainer().getLockingPolicy().getMode() !=
                      LockingPolicy.MODE_RECORD) ||
                          (open_conglom.isUseUpdateLocks())),
                "Current mode of container requires row locking.");


            // make sure current_rh and current_slot are in sync
            SanityManager.ASSERT(
                slot == page.getSlotNumber(scan_position.current_rh));
        }


        boolean ret_val;
        if (page.isDeletedAtSlot(slot)) {
            ret_val = false;
        } else {
            page.updateAtSlot(slot, row, validColumns);
            ret_val = true;
        }


        scan_position.unlatch();

View Full Code Here

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