84 lines
3.1 KiB
C
84 lines
3.1 KiB
C
/************************************************************************
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* @file implementation of variable-sized slotted pages
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STRUCTURE OF A PAGE
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<pre>
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+-----------------------------------------+-----------------------+----+
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| DATA SECTION +--------->| RID: (PAGE, 0) | |
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| +-----------------+ | +-----------------------+ |
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| +-->| RID: (PAGE, 1) | | |
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| | +-----------------+ | |
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| | | |
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| ----------------+ | +------------------------------+
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| | | +--->| RID: (PAGE, n) |
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| | | | +------------------------------+
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|======================================================================|
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| ^ FREE SPACE | | | |
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| | | | | |
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| +-------------------|-------|---|--------------------+ |
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| | | | | |
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| +-------------|-------|---+ | |
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| | | | | |
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| +---|---+-----+---|---+---|---+--------------+-----|------+-------+
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| | slotn | ... | slot1 | slot0 | num of slots | free space | *** |
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+----+-------+-----+-------+-------+--------------+------------+-------+
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</pre>
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*** = @see page.h for information on this field.
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NOTE:
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- slots are zero indexed.
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- slots are of implemented as (offset, length)
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Slotted page layout:
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END:
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lsn (4 bytes)
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type (2 bytes)
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free space (2 bytes)
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num of slots (2 bytes)
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freelist head(2 bytes)
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slot 0 (4 bytes)
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slot 1 (4 bytes)
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...
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slot n (4 bytes)
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...
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unused
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...
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record n (x bytes)
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...
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record 0 (y bytes)
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record 1 (z bytes)
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START
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$Id$
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@todo slotted.c Should know that specific record types (like blobs) exist,
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(but should not hardcode information about these types) This
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has been handled, except in slottedPostRalloc...
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************************************************************************/
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#define SLOTTED_PAGE_OVERHEAD_PER_RECORD (2 * sizeof(short))
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#define SLOTTED_PAGE_HEADER_OVERHEAD (3 * sizeof(short))
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//#define SLOTTED_PAGE_CHECK_FOR_OVERLAP 1
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//#define SLOTTED_PAGE_SKIP_SANITY_CHECKS 1
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#ifdef LONG_TEST
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#define SLOTTED_PAGE_CHECK_FOR_OVERLAP 1
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#endif
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#define freespace_ptr(page) shorts_from_end((page), 1)
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#define numslots_ptr(page) shorts_from_end((page), 2)
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#define freelist_ptr(page) shorts_from_end((page), 3)
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#define slot_ptr(page, n) shorts_from_end((page), (2*(n))+4)
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#define slot_length_ptr(page, n) shorts_from_end((page), (2*(n))+5)
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#define record_ptr(page, n) bytes_from_start((page), *slot_ptr((page), (n)))
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#define isValidSlot(page, n) ((*slot_ptr((page), (n)) == INVALID_SLOT) ? 0 : 1)
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void slottedPageInit();
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void slottedPageDeinit();
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page_impl slottedImpl();
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page_impl boundaryTagImpl();
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