trx0rseg.h

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/** @file include/trx0rseg.h
 Rollback segment
 
 Created 3/26/1996 Heikki Tuuri
 *******************************************************/
 
#ifndef trx0rseg_h
#define trx0rseg_h
 
#include <vector>
#include "fut0lst.h"
#include "trx0sys.h"
#include "trx0types.h"
#include "univ.i"
 
/** Gets a rollback segment header.
@param[in]      space           Space where placed
@param[in]      page_no         Page number of the header
@param[in]      page_size       Page size
@param[in,out]  mtr             Mini-transaction
@return rollback segment header, page x-latched */
static inline trx_rsegf_t *trx_rsegf_get(space_id_t space, page_no_t page_no,
                                         const page_size_t &page_size,
                                         mtr_t *mtr);
 
/** Gets a newly created rollback segment header.
@param[in]      space           Space where placed
@param[in]      page_no         Page number of the header
@param[in]      page_size       Page size
@param[in,out]  mtr             Mini-transaction
@return rollback segment header, page x-latched */
static inline trx_rsegf_t *trx_rsegf_get_new(space_id_t space,
                                             page_no_t page_no,
                                             const page_size_t &page_size,
                                             mtr_t *mtr);
 
/** Return a page number from a slot in the rseg_array page of an
undo tablespace.
@param[in]      space_id        undo tablespace ID
@param[in]      rseg_id         rollback segment ID
@return page_no Page number of the rollback segment header page */
page_no_t trx_rseg_get_page_no(space_id_t space_id, ulint rseg_id);
 
/** Gets the file page number of the nth undo log slot.
@param[in]      rsegf   rollback segment header
@param[in]      n       index of slot
@param[in]      mtr     mtr
@return page number of the undo log segment */
static inline page_no_t trx_rsegf_get_nth_undo(trx_rsegf_t *rsegf, ulint n,
                                               mtr_t *mtr);
 
/** Sets the file page number of the nth undo log slot.
@param[in]      rsegf   rollback segment header
@param[in]      n       index of slot
@param[in]      page_no page number of the undo log segment
@param[in]      mtr     mtr */
static inline void trx_rsegf_set_nth_undo(trx_rsegf_t *rsegf, ulint n,
                                          page_no_t page_no, mtr_t *mtr);
 
/** Looks for a free slot for an undo log segment.
@param[in]      rsegf   rollback segment header
@param[in]      mtr     mtr
@return slot index or ULINT_UNDEFINED if not found */
static inline ulint trx_rsegf_undo_find_free(trx_rsegf_t *rsegf, mtr_t *mtr);
 
/** Creates a rollback segment header.
This function is called only when a new rollback segment is created in
the database.
@param[in]      space_id        Space id
@param[in]      page_size       Page size
@param[in]      max_size        Max size in pages
@param[in]      rseg_slot       Rseg id == slot number in RSEG_ARRAY
@param[in,out]  mtr             Mini-transaction
@return page number of the created segment, FIL_NULL if fail */
page_no_t trx_rseg_header_create(space_id_t space_id,
                                 const page_size_t &page_size,
                                 page_no_t max_size, ulint rseg_slot,
                                 mtr_t *mtr);
 
/** Add more rsegs to the rseg list in each tablespace until there are
srv_rollback_segments of them.  Use any rollback segment that already
exists so that the purge_queue can be filled and processed with any
existing undo log. If the rollback segments do not exist in this
tablespace and we need them according to target_rollback_segments,
then build them in the tablespace.
@param[in]      target_rollback_segments        new number of rollback
                                                segments per space
@return true if all necessary rollback segments and trx_rseg_t objects
were created. */
bool trx_rseg_adjust_rollback_segments(ulong target_rollback_segments);
 
/** Create the requested number of Rollback Segments in a newly created undo
tablespace and add them to the Rsegs object.
@param[in]  space_id                  undo tablespace ID
@param[in]  target_rollback_segments  number of rollback segments per space
@return true if all necessary rollback segments and trx_rseg_t objects
were created. */
bool trx_rseg_init_rollback_segments(space_id_t space_id,
                                     ulong target_rollback_segments);
 
/** Read each rollback segment slot in the TRX_SYS page and the RSEG_ARRAY
page of each undo tablespace. Create trx_rseg_t objects for all rollback
segments found.  This runs at database startup and initializes the in-memory
lists of trx_rseg_t objects.  We need to look at all slots in TRX_SYS and
each RSEG_ARRAY page because we need to look for any existing undo log that
may need to be recovered by purge.  No latch is needed since this is still
single-threaded startup.  If we find existing rseg slots in TRX_SYS page
that reference undo tablespaces and have active undo logs, then quit.
They require an upgrade of undo tablespaces and that cannot happen with
active undo logs.
@param[in]      purge_queue     queue of rsegs to purge */
void trx_rsegs_init(purge_pq_t *purge_queue);
 
/** Initialize rollback segments in parallel
@param[in]      purge_queue     queue of rsegs to purge */
void trx_rsegs_parallel_init(purge_pq_t *purge_queue);
 
/** Create and initialize a rollback segment object.  Some of
the values for the fields are read from the segment header page.
The caller must insert it into the correct list.
@param[in]      id              Rollback segment id
@param[in]      space_id        Space where the segment is placed
@param[in]      page_no         Page number of the segment header
@param[in]      page_size       Page size
@param[in]      gtid_trx_no     Trx number up to which GTID is persisted
@param[in,out]  purge_queue     Rseg queue
@param[in,out]  mtr             Mini-transaction
@return own: rollback segment object */
trx_rseg_t *trx_rseg_mem_create(ulint id, space_id_t space_id,
                                page_no_t page_no, const page_size_t &page_size,
                                trx_id_t gtid_trx_no, purge_pq_t *purge_queue,
                                mtr_t *mtr);
 
/** Create a rollback segment in the given tablespace. This could be either
the system tablespace, the temporary tablespace, or an undo tablespace.
@param[in]      space_id        tablespace to get the rollback segment
@param[in]      rseg_id         slot number of the rseg within this tablespace
@return page number of the rollback segment header page created */
page_no_t trx_rseg_create(space_id_t space_id, ulint rseg_id);
 
/** Create the file page for the rollback segment directory in an undo
tablespace. This function is called just after an undo tablespace is
created so the next page created here should by FSP_FSEG_DIR_PAGE_NUM.
@param[in]      space_id        Undo Tablespace ID
@param[in]      mtr             mtr */
void trx_rseg_array_create(space_id_t space_id, mtr_t *mtr);
 
/** Sets the page number of the nth rollback segment slot in the
independent undo tablespace.
@param[in]      rsegs_header    rollback segment array page header
@param[in]      slot            slot number on page  == rseg id
@param[in]      page_no         rollback regment header page number
@param[in]      mtr             mtr */
static inline void trx_rsegsf_set_page_no(trx_rsegsf_t *rsegs_header,
                                          ulint slot, page_no_t page_no,
                                          mtr_t *mtr);
 
/** Number of undo log slots in a rollback segment file copy */
#define TRX_RSEG_N_SLOTS (UNIV_PAGE_SIZE / 16)
 
/** Maximum number of transactions supported by a single rollback segment */
#define TRX_RSEG_MAX_N_TRXS (TRX_RSEG_N_SLOTS / 2)
 
/* Undo log segment slot in a rollback segment header */
/*-------------------------------------------------------------*/
/** Page number of the header page of  an undo log segment */
constexpr uint32_t TRX_RSEG_SLOT_PAGE_NO = 0;
/*-------------------------------------------------------------*/
/** Slot size */
constexpr uint32_t TRX_RSEG_SLOT_SIZE = 4;
 
/** The offset of the rollback segment header on its page */
constexpr uint32_t TRX_RSEG = FSEG_PAGE_DATA;
 
/* Transaction rollback segment header */
/*-------------------------------------------------------------*/
/** Maximum allowed size for rollback segment in pages */
constexpr uint32_t TRX_RSEG_MAX_SIZE = 0;
/** Number of file pages occupied by the logs in the history list */
constexpr uint32_t TRX_RSEG_HISTORY_SIZE = 4;
/* The update undo logs for committed transactions */
constexpr uint32_t TRX_RSEG_HISTORY = 8;
/* Header for the file segment where this page is placed */
constexpr uint32_t TRX_RSEG_FSEG_HEADER = 8 + FLST_BASE_NODE_SIZE;
/** Undo log segment slots */
constexpr uint32_t TRX_RSEG_UNDO_SLOTS =
    8 + FLST_BASE_NODE_SIZE + FSEG_HEADER_SIZE;
 
/** End of undo slots in rollback segment page. */
#define TRX_RSEG_SLOT_END \
  (TRX_RSEG_UNDO_SLOTS + TRX_RSEG_SLOT_SIZE * TRX_RSEG_N_SLOTS)
 
/* Maximum transaction number ever added to this rollback segment history
list. It is always increasing number over lifetime starting from zero.
The size is 8 bytes. */
#define TRX_RSEG_MAX_TRX_NO TRX_RSEG_SLOT_END
 
/*-------------------------------------------------------------*/
 
/** The offset of the Rollback Segment Directory header on an RSEG_ARRAY
   page */
constexpr uint32_t RSEG_ARRAY_HEADER = FSEG_PAGE_DATA;
 
/** Rollback Segment Array Header */
/*------------------------------------------------------------- */
/** The RSEG ARRAY base version is a number derived from the string
'RSEG' [0x 52 53 45 47] for extra validation. Each new version
increments the base version by 1. */
constexpr uint32_t RSEG_ARRAY_VERSION = 0x52534547 + 1;
 
/** The RSEG ARRAY version offset in the header. */
constexpr uint32_t RSEG_ARRAY_VERSION_OFFSET = 0;
 
/** The current number of rollback segments being tracked in this array */
constexpr uint32_t RSEG_ARRAY_SIZE_OFFSET = 4;
 
/** This is the pointer to the file segment inode that tracks this
rseg array page. */
constexpr uint32_t RSEG_ARRAY_FSEG_HEADER_OFFSET = 8;
 
/** The start of the array of rollback segment header page numbers for this
undo tablespace. The potential size of this array is limited only by the
page size minus overhead. The actual size of the array is limited by
srv_rollback_segments. */
constexpr uint32_t RSEG_ARRAY_PAGES_OFFSET = 8 + FSEG_HEADER_SIZE;
 
/** Reserved space at the end of an RSEG_ARRAY page reserved for future use.
 */
constexpr uint32_t RSEG_ARRAY_RESERVED_BYTES = 200;
 
/* Slot size of the array of rollback segment header page numbers */
constexpr uint32_t RSEG_ARRAY_SLOT_SIZE = 4;
/*------------------------------------------------------------- */
 
#include "trx0rseg.ic"
 
#endif