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Diffstat (limited to 'storage/xtradb/row/row0vers.c')
| -rw-r--r-- | storage/xtradb/row/row0vers.c | 741 |
1 files changed, 741 insertions, 0 deletions
diff --git a/storage/xtradb/row/row0vers.c b/storage/xtradb/row/row0vers.c new file mode 100644 index 00000000000..3abba6d6fb8 --- /dev/null +++ b/storage/xtradb/row/row0vers.c @@ -0,0 +1,741 @@ +/***************************************************************************** + +Copyright (c) 1997, 2009, Innobase Oy. All Rights Reserved. + +This program is free software; you can redistribute it and/or modify it under +the terms of the GNU General Public License as published by the Free Software +Foundation; version 2 of the License. + +This program is distributed in the hope that it will be useful, but WITHOUT +ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS +FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. + +You should have received a copy of the GNU General Public License along with +this program; if not, write to the Free Software Foundation, Inc., 59 Temple +Place, Suite 330, Boston, MA 02111-1307 USA + +*****************************************************************************/ + +/****************************************************** +Row versions + +Created 2/6/1997 Heikki Tuuri +*******************************************************/ + +#include "row0vers.h" + +#ifdef UNIV_NONINL +#include "row0vers.ic" +#endif + +#include "dict0dict.h" +#include "dict0boot.h" +#include "btr0btr.h" +#include "mach0data.h" +#include "trx0rseg.h" +#include "trx0trx.h" +#include "trx0roll.h" +#include "trx0undo.h" +#include "trx0purge.h" +#include "trx0rec.h" +#include "que0que.h" +#include "row0row.h" +#include "row0upd.h" +#include "rem0cmp.h" +#include "read0read.h" +#include "lock0lock.h" + +/********************************************************************* +Finds out if an active transaction has inserted or modified a secondary +index record. NOTE: the kernel mutex is temporarily released in this +function! */ +UNIV_INTERN +trx_t* +row_vers_impl_x_locked_off_kernel( +/*==============================*/ + /* out: NULL if committed, else the active + transaction; NOTE that the kernel mutex is + temporarily released! */ + const rec_t* rec, /* in: record in a secondary index */ + dict_index_t* index, /* in: the secondary index */ + const ulint* offsets)/* in: rec_get_offsets(rec, index) */ +{ + dict_index_t* clust_index; + rec_t* clust_rec; + ulint* clust_offsets; + rec_t* version; + dulint trx_id; + mem_heap_t* heap; + mem_heap_t* heap2; + dtuple_t* row; + dtuple_t* entry = NULL; /* assignment to eliminate compiler + warning */ + trx_t* trx; + ulint rec_del; + ulint err; + mtr_t mtr; + ulint comp; + + ut_ad(mutex_own(&kernel_mutex)); +#ifdef UNIV_SYNC_DEBUG + ut_ad(!rw_lock_own(&(purge_sys->latch), RW_LOCK_SHARED)); +#endif /* UNIV_SYNC_DEBUG */ + + mutex_exit(&kernel_mutex); + + mtr_start(&mtr); + + /* Search for the clustered index record: this is a time-consuming + operation: therefore we release the kernel mutex; also, the release + is required by the latching order convention. The latch on the + clustered index locks the top of the stack of versions. We also + reserve purge_latch to lock the bottom of the version stack. */ + + clust_rec = row_get_clust_rec(BTR_SEARCH_LEAF, rec, index, + &clust_index, &mtr); + if (!clust_rec) { + /* In a rare case it is possible that no clust rec is found + for a secondary index record: if in row0umod.c + row_undo_mod_remove_clust_low() we have already removed the + clust rec, while purge is still cleaning and removing + secondary index records associated with earlier versions of + the clustered index record. In that case there cannot be + any implicit lock on the secondary index record, because + an active transaction which has modified the secondary index + record has also modified the clustered index record. And in + a rollback we always undo the modifications to secondary index + records before the clustered index record. */ + + mutex_enter(&kernel_mutex); + mtr_commit(&mtr); + + return(NULL); + } + + heap = mem_heap_create(1024); + clust_offsets = rec_get_offsets(clust_rec, clust_index, NULL, + ULINT_UNDEFINED, &heap); + trx_id = row_get_rec_trx_id(clust_rec, clust_index, clust_offsets); + + mtr_s_lock(&(purge_sys->latch), &mtr); + + mutex_enter(&kernel_mutex); + + trx = NULL; + if (!trx_is_active(trx_id)) { + /* The transaction that modified or inserted clust_rec is no + longer active: no implicit lock on rec */ + goto exit_func; + } + + if (!lock_check_trx_id_sanity(trx_id, clust_rec, clust_index, + clust_offsets, TRUE)) { + /* Corruption noticed: try to avoid a crash by returning */ + goto exit_func; + } + + comp = page_rec_is_comp(rec); + ut_ad(index->table == clust_index->table); + ut_ad(!!comp == dict_table_is_comp(index->table)); + ut_ad(!comp == !page_rec_is_comp(clust_rec)); + + /* We look up if some earlier version, which was modified by the trx_id + transaction, of the clustered index record would require rec to be in + a different state (delete marked or unmarked, or have different field + values, or not existing). If there is such a version, then rec was + modified by the trx_id transaction, and it has an implicit x-lock on + rec. Note that if clust_rec itself would require rec to be in a + different state, then the trx_id transaction has not yet had time to + modify rec, and does not necessarily have an implicit x-lock on rec. */ + + rec_del = rec_get_deleted_flag(rec, comp); + trx = NULL; + + version = clust_rec; + + for (;;) { + rec_t* prev_version; + ulint vers_del; + row_ext_t* ext; + dulint prev_trx_id; + + mutex_exit(&kernel_mutex); + + /* While we retrieve an earlier version of clust_rec, we + release the kernel mutex, because it may take time to access + the disk. After the release, we have to check if the trx_id + transaction is still active. We keep the semaphore in mtr on + the clust_rec page, so that no other transaction can update + it and get an implicit x-lock on rec. */ + + heap2 = heap; + heap = mem_heap_create(1024); + err = trx_undo_prev_version_build(clust_rec, &mtr, version, + clust_index, clust_offsets, + heap, &prev_version); + mem_heap_free(heap2); /* free version and clust_offsets */ + + if (prev_version == NULL) { + mutex_enter(&kernel_mutex); + + if (!trx_is_active(trx_id)) { + /* Transaction no longer active: no + implicit x-lock */ + + break; + } + + /* If the transaction is still active, + clust_rec must be a fresh insert, because no + previous version was found. */ + ut_ad(err == DB_SUCCESS); + + /* It was a freshly inserted version: there is an + implicit x-lock on rec */ + + trx = trx_get_on_id(trx_id); + + break; + } + + clust_offsets = rec_get_offsets(prev_version, clust_index, + NULL, ULINT_UNDEFINED, &heap); + + vers_del = rec_get_deleted_flag(prev_version, comp); + prev_trx_id = row_get_rec_trx_id(prev_version, clust_index, + clust_offsets); + + /* If the trx_id and prev_trx_id are different and if + the prev_version is marked deleted then the + prev_trx_id must have already committed for the trx_id + to be able to modify the row. Therefore, prev_trx_id + cannot hold any implicit lock. */ + if (vers_del && 0 != ut_dulint_cmp(trx_id, prev_trx_id)) { + + mutex_enter(&kernel_mutex); + break; + } + + /* The stack of versions is locked by mtr. Thus, it + is safe to fetch the prefixes for externally stored + columns. */ + row = row_build(ROW_COPY_POINTERS, clust_index, prev_version, + clust_offsets, NULL, &ext, heap); + entry = row_build_index_entry(row, ext, index, heap); + /* entry may be NULL if a record was inserted in place + of a deleted record, and the BLOB pointers of the new + record were not initialized yet. But in that case, + prev_version should be NULL. */ + ut_a(entry); + + mutex_enter(&kernel_mutex); + + if (!trx_is_active(trx_id)) { + /* Transaction no longer active: no implicit x-lock */ + + break; + } + + /* If we get here, we know that the trx_id transaction is + still active and it has modified prev_version. Let us check + if prev_version would require rec to be in a different + state. */ + + /* The previous version of clust_rec must be + accessible, because the transaction is still active + and clust_rec was not a fresh insert. */ + ut_ad(err == DB_SUCCESS); + + /* We check if entry and rec are identified in the alphabetical + ordering */ + if (0 == cmp_dtuple_rec(entry, rec, offsets)) { + /* The delete marks of rec and prev_version should be + equal for rec to be in the state required by + prev_version */ + + if (rec_del != vers_del) { + trx = trx_get_on_id(trx_id); + + break; + } + + /* It is possible that the row was updated so that the + secondary index record remained the same in + alphabetical ordering, but the field values changed + still. For example, 'abc' -> 'ABC'. Check also that. */ + + dtuple_set_types_binary(entry, + dtuple_get_n_fields(entry)); + if (0 != cmp_dtuple_rec(entry, rec, offsets)) { + + trx = trx_get_on_id(trx_id); + + break; + } + } else if (!rec_del) { + /* The delete mark should be set in rec for it to be + in the state required by prev_version */ + + trx = trx_get_on_id(trx_id); + + break; + } + + if (0 != ut_dulint_cmp(trx_id, prev_trx_id)) { + /* The versions modified by the trx_id transaction end + to prev_version: no implicit x-lock */ + + break; + } + + version = prev_version; + }/* for (;;) */ + +exit_func: + mtr_commit(&mtr); + mem_heap_free(heap); + + return(trx); +} + +/********************************************************************* +Finds out if we must preserve a delete marked earlier version of a clustered +index record, because it is >= the purge view. */ +UNIV_INTERN +ibool +row_vers_must_preserve_del_marked( +/*==============================*/ + /* out: TRUE if earlier version should be preserved */ + dulint trx_id, /* in: transaction id in the version */ + mtr_t* mtr) /* in: mtr holding the latch on the clustered index + record; it will also hold the latch on purge_view */ +{ +#ifdef UNIV_SYNC_DEBUG + ut_ad(!rw_lock_own(&(purge_sys->latch), RW_LOCK_SHARED)); +#endif /* UNIV_SYNC_DEBUG */ + + mtr_s_lock(&(purge_sys->latch), mtr); + + if (trx_purge_update_undo_must_exist(trx_id)) { + + /* A purge operation is not yet allowed to remove this + delete marked record */ + + return(TRUE); + } + + return(FALSE); +} + +/********************************************************************* +Finds out if a version of the record, where the version >= the current +purge view, should have ientry as its secondary index entry. We check +if there is any not delete marked version of the record where the trx +id >= purge view, and the secondary index entry and ientry are identified in +the alphabetical ordering; exactly in this case we return TRUE. */ +UNIV_INTERN +ibool +row_vers_old_has_index_entry( +/*=========================*/ + /* out: TRUE if earlier version should have */ + ibool also_curr,/* in: TRUE if also rec is included in the + versions to search; otherwise only versions + prior to it are searched */ + const rec_t* rec, /* in: record in the clustered index; the + caller must have a latch on the page */ + mtr_t* mtr, /* in: mtr holding the latch on rec; it will + also hold the latch on purge_view */ + dict_index_t* index, /* in: the secondary index */ + const dtuple_t* ientry) /* in: the secondary index entry */ +{ + const rec_t* version; + rec_t* prev_version; + dict_index_t* clust_index; + ulint* clust_offsets; + mem_heap_t* heap; + mem_heap_t* heap2; + const dtuple_t* row; + const dtuple_t* entry; + ulint err; + ulint comp; + + ut_ad(mtr_memo_contains_page(mtr, rec, MTR_MEMO_PAGE_X_FIX) + || mtr_memo_contains_page(mtr, rec, MTR_MEMO_PAGE_S_FIX)); +#ifdef UNIV_SYNC_DEBUG + ut_ad(!rw_lock_own(&(purge_sys->latch), RW_LOCK_SHARED)); +#endif /* UNIV_SYNC_DEBUG */ + mtr_s_lock(&(purge_sys->latch), mtr); + + clust_index = dict_table_get_first_index(index->table); + + comp = page_rec_is_comp(rec); + ut_ad(!dict_table_is_comp(index->table) == !comp); + heap = mem_heap_create(1024); + clust_offsets = rec_get_offsets(rec, clust_index, NULL, + ULINT_UNDEFINED, &heap); + + if (also_curr && !rec_get_deleted_flag(rec, comp)) { + row_ext_t* ext; + + /* The stack of versions is locked by mtr. + Thus, it is safe to fetch the prefixes for + externally stored columns. */ + row = row_build(ROW_COPY_POINTERS, clust_index, + rec, clust_offsets, NULL, &ext, heap); + entry = row_build_index_entry(row, ext, index, heap); + + /* If entry == NULL, the record contains unset BLOB + pointers. This must be a freshly inserted record. If + this is called from + row_purge_remove_sec_if_poss_low(), the thread will + hold latches on the clustered index and the secondary + index. Because the insert works in three steps: + + (1) insert the record to clustered index + (2) store the BLOBs and update BLOB pointers + (3) insert records to secondary indexes + + the purge thread can safely ignore freshly inserted + records and delete the secondary index record. The + thread that inserted the new record will be inserting + the secondary index records. */ + + /* NOTE that we cannot do the comparison as binary + fields because the row is maybe being modified so that + the clustered index record has already been updated to + a different binary value in a char field, but the + collation identifies the old and new value anyway! */ + if (entry && !dtuple_coll_cmp(ientry, entry)) { + + mem_heap_free(heap); + + return(TRUE); + } + } + + version = rec; + + for (;;) { + heap2 = heap; + heap = mem_heap_create(1024); + err = trx_undo_prev_version_build(rec, mtr, version, + clust_index, clust_offsets, + heap, &prev_version); + mem_heap_free(heap2); /* free version and clust_offsets */ + + if (err != DB_SUCCESS || !prev_version) { + /* Versions end here */ + + mem_heap_free(heap); + + return(FALSE); + } + + clust_offsets = rec_get_offsets(prev_version, clust_index, + NULL, ULINT_UNDEFINED, &heap); + + if (!rec_get_deleted_flag(prev_version, comp)) { + row_ext_t* ext; + + /* The stack of versions is locked by mtr. + Thus, it is safe to fetch the prefixes for + externally stored columns. */ + row = row_build(ROW_COPY_POINTERS, clust_index, + prev_version, clust_offsets, + NULL, &ext, heap); + entry = row_build_index_entry(row, ext, index, heap); + + /* If entry == NULL, the record contains unset + BLOB pointers. This must be a freshly + inserted record that we can safely ignore. + For the justification, see the comments after + the previous row_build_index_entry() call. */ + + /* NOTE that we cannot do the comparison as binary + fields because maybe the secondary index record has + already been updated to a different binary value in + a char field, but the collation identifies the old + and new value anyway! */ + + if (entry && !dtuple_coll_cmp(ientry, entry)) { + + mem_heap_free(heap); + + return(TRUE); + } + } + + version = prev_version; + } +} + +/********************************************************************* +Constructs the version of a clustered index record which a consistent +read should see. We assume that the trx id stored in rec is such that +the consistent read should not see rec in its present version. */ +UNIV_INTERN +ulint +row_vers_build_for_consistent_read( +/*===============================*/ + /* out: DB_SUCCESS or DB_MISSING_HISTORY */ + const rec_t* rec, /* in: record in a clustered index; the + caller must have a latch on the page; this + latch locks the top of the stack of versions + of this records */ + mtr_t* mtr, /* in: mtr holding the latch on rec */ + dict_index_t* index, /* in: the clustered index */ + ulint** offsets,/* in/out: offsets returned by + rec_get_offsets(rec, index) */ + read_view_t* view, /* in: the consistent read view */ + mem_heap_t** offset_heap,/* in/out: memory heap from which + the offsets are allocated */ + mem_heap_t* in_heap,/* in: memory heap from which the memory for + *old_vers is allocated; memory for possible + intermediate versions is allocated and freed + locally within the function */ + rec_t** old_vers)/* out, own: old version, or NULL if the + record does not exist in the view, that is, + it was freshly inserted afterwards */ +{ + const rec_t* version; + rec_t* prev_version; + dulint trx_id; + mem_heap_t* heap = NULL; + byte* buf; + ulint err; + + ut_ad(dict_index_is_clust(index)); + ut_ad(mtr_memo_contains_page(mtr, rec, MTR_MEMO_PAGE_X_FIX) + || mtr_memo_contains_page(mtr, rec, MTR_MEMO_PAGE_S_FIX)); +#ifdef UNIV_SYNC_DEBUG + ut_ad(!rw_lock_own(&(purge_sys->latch), RW_LOCK_SHARED)); +#endif /* UNIV_SYNC_DEBUG */ + + ut_ad(rec_offs_validate(rec, index, *offsets)); + + trx_id = row_get_rec_trx_id(rec, index, *offsets); + + ut_ad(!read_view_sees_trx_id(view, trx_id)); + + rw_lock_s_lock(&(purge_sys->latch)); + version = rec; + + for (;;) { + mem_heap_t* heap2 = heap; + trx_undo_rec_t* undo_rec; + dulint roll_ptr; + dulint undo_no; + heap = mem_heap_create(1024); + + /* If we have high-granularity consistent read view and + creating transaction of the view is the same as trx_id in + the record we see this record only in the case when + undo_no of the record is < undo_no in the view. */ + + if (view->type == VIEW_HIGH_GRANULARITY + && ut_dulint_cmp(view->creator_trx_id, trx_id) == 0) { + + roll_ptr = row_get_rec_roll_ptr(version, index, + *offsets); + undo_rec = trx_undo_get_undo_rec_low(roll_ptr, heap); + undo_no = trx_undo_rec_get_undo_no(undo_rec); + mem_heap_empty(heap); + + if (ut_dulint_cmp(view->undo_no, undo_no) > 0) { + /* The view already sees this version: we can + copy it to in_heap and return */ + + buf = mem_heap_alloc(in_heap, + rec_offs_size(*offsets)); + *old_vers = rec_copy(buf, version, *offsets); + rec_offs_make_valid(*old_vers, index, + *offsets); + err = DB_SUCCESS; + + break; + } + } + + err = trx_undo_prev_version_build(rec, mtr, version, index, + *offsets, heap, + &prev_version); + if (heap2) { + mem_heap_free(heap2); /* free version */ + } + + if (err != DB_SUCCESS) { + break; + } + + if (prev_version == NULL) { + /* It was a freshly inserted version */ + *old_vers = NULL; + err = DB_SUCCESS; + + break; + } + + *offsets = rec_get_offsets(prev_version, index, *offsets, + ULINT_UNDEFINED, offset_heap); + + trx_id = row_get_rec_trx_id(prev_version, index, *offsets); + + if (read_view_sees_trx_id(view, trx_id)) { + + /* The view already sees this version: we can copy + it to in_heap and return */ + + buf = mem_heap_alloc(in_heap, rec_offs_size(*offsets)); + *old_vers = rec_copy(buf, prev_version, *offsets); + rec_offs_make_valid(*old_vers, index, *offsets); + err = DB_SUCCESS; + + break; + } + + version = prev_version; + }/* for (;;) */ + + mem_heap_free(heap); + rw_lock_s_unlock(&(purge_sys->latch)); + + return(err); +} + +/********************************************************************* +Constructs the last committed version of a clustered index record, +which should be seen by a semi-consistent read. */ +UNIV_INTERN +ulint +row_vers_build_for_semi_consistent_read( +/*====================================*/ + /* out: DB_SUCCESS or DB_MISSING_HISTORY */ + const rec_t* rec, /* in: record in a clustered index; the + caller must have a latch on the page; this + latch locks the top of the stack of versions + of this records */ + mtr_t* mtr, /* in: mtr holding the latch on rec */ + dict_index_t* index, /* in: the clustered index */ + ulint** offsets,/* in/out: offsets returned by + rec_get_offsets(rec, index) */ + mem_heap_t** offset_heap,/* in/out: memory heap from which + the offsets are allocated */ + mem_heap_t* in_heap,/* in: memory heap from which the memory for + *old_vers is allocated; memory for possible + intermediate versions is allocated and freed + locally within the function */ + const rec_t** old_vers)/* out: rec, old version, or NULL if the + record does not exist in the view, that is, + it was freshly inserted afterwards */ +{ + const rec_t* version; + mem_heap_t* heap = NULL; + byte* buf; + ulint err; + dulint rec_trx_id = ut_dulint_zero; + + ut_ad(dict_index_is_clust(index)); + ut_ad(mtr_memo_contains_page(mtr, rec, MTR_MEMO_PAGE_X_FIX) + || mtr_memo_contains_page(mtr, rec, MTR_MEMO_PAGE_S_FIX)); +#ifdef UNIV_SYNC_DEBUG + ut_ad(!rw_lock_own(&(purge_sys->latch), RW_LOCK_SHARED)); +#endif /* UNIV_SYNC_DEBUG */ + + ut_ad(rec_offs_validate(rec, index, *offsets)); + + rw_lock_s_lock(&(purge_sys->latch)); + /* The S-latch on purge_sys prevents the purge view from + changing. Thus, if we have an uncommitted transaction at + this point, then purge cannot remove its undo log even if + the transaction could commit now. */ + + version = rec; + + for (;;) { + trx_t* version_trx; + mem_heap_t* heap2; + rec_t* prev_version; + dulint version_trx_id; + + version_trx_id = row_get_rec_trx_id(version, index, *offsets); + if (rec == version) { + rec_trx_id = version_trx_id; + } + + mutex_enter(&kernel_mutex); + version_trx = trx_get_on_id(version_trx_id); + mutex_exit(&kernel_mutex); + + if (!version_trx + || version_trx->conc_state == TRX_NOT_STARTED + || version_trx->conc_state == TRX_COMMITTED_IN_MEMORY) { + + /* We found a version that belongs to a + committed transaction: return it. */ + + if (rec == version) { + *old_vers = rec; + err = DB_SUCCESS; + break; + } + + /* We assume that a rolled-back transaction stays in + TRX_ACTIVE state until all the changes have been + rolled back and the transaction is removed from + the global list of transactions. */ + + if (!ut_dulint_cmp(rec_trx_id, version_trx_id)) { + /* The transaction was committed while + we searched for earlier versions. + Return the current version as a + semi-consistent read. */ + + version = rec; + *offsets = rec_get_offsets(version, + index, *offsets, + ULINT_UNDEFINED, + offset_heap); + } + + buf = mem_heap_alloc(in_heap, rec_offs_size(*offsets)); + *old_vers = rec_copy(buf, version, *offsets); + rec_offs_make_valid(*old_vers, index, *offsets); + err = DB_SUCCESS; + + break; + } + + heap2 = heap; + heap = mem_heap_create(1024); + + err = trx_undo_prev_version_build(rec, mtr, version, index, + *offsets, heap, + &prev_version); + if (heap2) { + mem_heap_free(heap2); /* free version */ + } + + if (UNIV_UNLIKELY(err != DB_SUCCESS)) { + break; + } + + if (prev_version == NULL) { + /* It was a freshly inserted version */ + *old_vers = NULL; + err = DB_SUCCESS; + + break; + } + + version = prev_version; + *offsets = rec_get_offsets(version, index, *offsets, + ULINT_UNDEFINED, offset_heap); + }/* for (;;) */ + + if (heap) { + mem_heap_free(heap); + } + rw_lock_s_unlock(&(purge_sys->latch)); + + return(err); +} |