195 lines
11 KiB
C
195 lines
11 KiB
C
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/****************************************************************
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* *
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* Copyright 2001, 2011 Fidelity Information Services, Inc *
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* *
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* This source code contains the intellectual property *
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* of its copyright holder(s), and is made available *
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* under a license. If you do not know the terms of *
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* the license, please stop and do not read further. *
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* *
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****************************************************************/
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#ifndef __GDSCC_H__
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#define __GDSCC_H__
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/* this requires gdsroot.h gtm_facilit.h fileinfo.h gdsbt.h gdsfhead.h gdir.h gdskey.h */
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#include <sys/types.h>
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/* BIG_UA is the maximum size of a single update array specified as an unsigned quantity (usages rely on this). It is 16MB. */
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#define BIG_UA (uint4)16777216
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#define CDB_R_SET_SIZE 32
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#define CDB_CW_SET_SIZE (MAX_BT_DEPTH * 3 + 1 + 2)
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#define CDB_W_SET_SIZE 16
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/* CDB_CW_SET_SIZE = 24
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* 3 for all the levels (including updated block, newly created sibling and possible bitmap update)
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* 1 extra for the root level (to take care of gds_t_write_root case)
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* 2 in the case of creation of a new global variable (1 index block with a * key and 1 data block
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* containing the key)
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*/
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#define CDB_T_CREATE 0
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#define CDB_T_WRITE 1
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#define CDB_T_WRITE_ROOT 2
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/* The following defines the write_type for a block that is going to be updated.
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* GDS_WRITE_PLAIN is the default type for most updates.
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* GDS_WRITE_BLOCK_SPLIT is set in case of a block update due to a block split. It is currently not used anywhere in the code.
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* GDS_WRITE_KILLTN requires a little more explanation.
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*
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* The TP commit logic ("tp_tend") makes use of an optimization referred to as the "indexmod" optimization.
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* This optimization tries to avoid a restart in the case where a TP transaction does a SET to a data block and later finds
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* at TCOMMIT time that the index block which was part of the SET had been updated by a concurrent SET (or a REORG split
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* operation) to a different data block (that also had the same index block as an ancestor) which resulted in a block split
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* causing the index block to be updated. In this case there is no reason to restart. The index block could have been
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* modified by other operations as well (e.g. M-kill, REORG coalesce or swap operations or any DSE command or a block split
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* operation that caused the height of the global variable tree to increase [C9B11-001813]). In these cases, we dont want
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* this optimization to take effect as we cant be sure everything that was relied upon for the TP transaction was still valid.
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* These disallowed operations are generically referred to as "kill" type of operations. This optimization is implemented by
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* having a field "killtn" (name derived from "kill" type of operations) in the bt (block-table) structure for each block.
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* This field is assigned the same value as the "tn" whenever an index block gets updated due to one of the disallowed operations.
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* Otherwise it stays untouched (i.e. killtn <= tn at all times). It is the "killtn" (and not "tn") that is used in the
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* cdb_sc_blkmod validation check in tp_tend if we are validating a index block. Since KILLs, MUPIP REORG and/or DSE operations
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* are usually rare compared to SET activity, most of the cases we expect the indexmod optimization to be in effect and
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* therefore help reduce the # of TP restarts due to index block changes. Note that each SET/GET/KILL operation in TP goes
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* through an intermediate validation routine tp_hist which does the cdb_sc_blkmod validation using "tn" (not "killtn").
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* Only if that passed, do we relax the commit time validation for index blocks.
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*
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* The operations that are not allowed to use this optimization (M-kill, REORG or DSE) are supposed to make sure they
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* set the write_type of the cw-set-element to GDS_WRITE_KILLTN. Failing to do so cause "killtn" in the bt to NOT be uptodate
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* which in turn can cause false validation passes (in the cdb_sc_blkmod check) causing GT.M processes to incorrectly commit
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* when they should not. This can lead to GT.M/application level data integrity errors.
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*/
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#define GDS_WRITE_PLAIN 0
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#define GDS_WRITE_KILLTN 1
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#define GDS_WRITE_BLOCK_SPLIT 2
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/* macro to traverse to the end of an horizontal cw_set_element list */
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#define TRAVERSE_TO_LATEST_CSE(x) \
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{ \
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GBLREF uint4 dollar_tlevel; \
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\
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assert(dollar_tlevel); \
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if (x) \
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for ( ; (x)->high_tlevel; x = (x)->high_tlevel) \
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; \
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}
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typedef uint4 block_offset;
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typedef int4 block_index;
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/* If a new mode is added to the table below, make sure pre-existing mode usages in the current codebase are examined to see
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* if the new mode needs to be added there as well. For example, there is code in tp_incr_commit.c and tp_incr_clean_up.c
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* where gds_t_create and kill_t_create are used explicitly. If the new mode is yet another *create* type, then it might need
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* to be added in those places as well.
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*/
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enum gds_t_mode
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{
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gds_t_noop = 0, /* there is code that initializes stuff to 0 relying on it being equal to gds_t_noop */
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gds_t_create,
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gds_t_write,
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gds_t_write_recycled, /* modify a recycled block (currently only done by MUPIP REORG UPGRADE/DOWNGRADE) */
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gds_t_acquired,
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gds_t_writemap,
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gds_t_committed, /* t_end relies on this particular placement */
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gds_t_write_root, /* t_end relies on this being AFTER gds_t_committed */
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gds_t_busy2free, /* t_end relies on this being AFTER gds_t_committed */
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n_gds_t_op, /* tp_tend and other routines rely on this being BEFORE kill_t* modes and AFTER all gds_t_* modes */
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kill_t_create, /* tp_tend relies on this being AFTER n_gds_t_op */
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kill_t_write, /* tp_tend relies on this being AFTER n_gds_t_op */
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};
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typedef struct key_value_struct
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{
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gv_key key; /* note that the following array holds the actual key contents */
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char key_contents[DBKEYSIZE(MAX_KEY_SZ)];
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mstr value;
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struct key_value_struct *next;
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} key_cum_value;
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/* Create/write set element. This is used to describe modification of a database block */
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typedef struct cw_set_element_struct
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{
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trans_num tn; /* transaction number for bit maps */
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sm_uc_ptr_t old_block; /* Address of 'before-image' of block to be over-written */
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cache_rec_ptr_t cr;
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struct cw_set_element_struct *next_cw_set;
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struct cw_set_element_struct *prev_cw_set; /* linked list (vertical) of cw_set_elements with one link per block */
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struct cw_set_element_struct *high_tlevel;
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struct cw_set_element_struct *low_tlevel; /* linked list (horizontal) of cw_set elements for a given block with
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* different transaction levels. Latest cw_set_elements (for a given block)
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* are inserted at the beginning of the horizontal list */
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off_jnl_t jnl_freeaddr; /* journal update address */
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uint4 write_type; /* can be GDS_WRITE_PLAIN or GDS_WRITE_KILLTN or GDS_WRITE_BLOCK_SPLIT
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* or bit-wise-or of both */
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key_cum_value *recompute_list_head; /* pointer to a list of keys (with values) that need to be recomputed */
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key_cum_value *recompute_list_tail; /* pointer to a list of keys (with values) that need to be recomputed */
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enum gds_t_mode mode; /* Create, write, or write root */
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block_id blk; /* Block number or a hint block number for creates */
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unsigned char *upd_addr; /* Address of the block segment array containing update info
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* for this block */
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unsigned char *new_buff; /* Address of a buffer created for each global mentioned inside of a
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* transaction more then once (for tp) */
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gv_namehead *blk_target; /* address of the "gv_target" associated with a new_buff
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* used to invalidate clues that point to malloc'ed copies */
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int4 cycle;
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/* When a block splits a new block must be created and the parent must be updated to
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* to have a record pointing to the new block. The created block number will not be
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* known until the last possible moment. Thus it is not possible to completely modify
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* the parent. The following 2 fields are used in such a case. "ins_off" tells where
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* the created block's number should be put in the parent block. "index" tells which
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* element of the create/write set is being created.
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*/
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block_offset first_off;
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block_offset ins_off; /* Insert block number offset */
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block_offset next_off;
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block_index index; /* Insert block number index */
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int4 reference_cnt; /* Relevant only for a bitmap block.
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* > 0 => # of non-bitmap blocks to be allocated in this bitmap;
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* < 0 => # of non-bitmap blocks to be freed up in this bitmap;
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* == 0 => change to bitmap block without any non-bitmap block change
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* Used to update csd->free_blocks when the bitmap block is built
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*/
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int4 level; /* Block level for newly created blocks */
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boolean_t done; /* Has this update been done already? */
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boolean_t first_copy; /* If overlaying same buffer, set if first copy needed */
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/* just an optimisation - avoids copying first few bytes, if anyway
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* we are just overlaying the new_buff in the same transaction */
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boolean_t forward_process; /* Need to process update array from front when doing kills */
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uint4 t_level; /* transaction level associated with cw element, for incremental rollback */
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enum db_ver ondsk_blkver; /* Actual block version from block header as it exists on disk.
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* If "cse->mode" is gds_t_write_root, this is uninitialized.
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* If "cse->mode" is gds_t_create/gds_t_acquired, this is GDSVCURR.
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* Otherwise, this is set to cr->ondsk_blkver (cr is got from the history).
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* Whenever "cse->old_block" is reset, this needs to be reset too (except
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* in the case of gds_t_create/gds_t_acquired).
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*/
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int4 old_mode; /* Saved copy of "cse->mode" before being reset to gds_t_committed.
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* Is negated at end of bg_update_phase1 to indicate (to secshr_db_clnup)
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* that phase1 is complete. Is negated back to the postive value at end
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* of bg_update_phase2. Since this can take on negative values, its type
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* is int4 (signed) and not enum gds_t_mode (which is unsigned).
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*/
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/* The following two fields aid in rolling back the transactions. 'undo_next_off' holds the
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* original next_off in the blk buffer that would be if another nested transaction was not
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* started. 'undo_offset' holds the offset at which 'undo_next_off' should be applied in case
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* of an undo due to trollback.
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* A 'kill' might change the next_off field at most in two places in the blk buffer. So, is
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* an array of size two.
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*/
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block_offset undo_next_off[2];
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block_offset undo_offset[2];
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uint4 blk_checksum;
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uint4 was_free;
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} cw_set_element;
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#endif
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