/* * __cursor_fix_prev -- * Move to the previous, fixed-length column-store item. */ static inline int __cursor_fix_prev(WT_CURSOR_BTREE *cbt, bool newpage) { WT_BTREE *btree; WT_ITEM *val; WT_PAGE *page; WT_SESSION_IMPL *session; WT_UPDATE *upd; session = (WT_SESSION_IMPL *)cbt->iface.session; page = cbt->ref->page; btree = S2BT(session); val = &cbt->iface.value; /* Initialize for each new page. */ if (newpage) { cbt->last_standard_recno = __col_fix_last_recno(page); if (cbt->last_standard_recno == 0) return (WT_NOTFOUND); __cursor_set_recno(cbt, cbt->last_standard_recno); goto new_page; } /* Move to the previous entry and return the item. */ if (cbt->recno == page->pg_fix_recno) return (WT_NOTFOUND); __cursor_set_recno(cbt, cbt->recno - 1); new_page: /* Check any insert list for a matching record. */ cbt->ins_head = WT_COL_UPDATE_SINGLE(page); cbt->ins = __col_insert_search( cbt->ins_head, cbt->ins_stack, cbt->next_stack, cbt->recno); if (cbt->ins != NULL && cbt->recno != WT_INSERT_RECNO(cbt->ins)) cbt->ins = NULL; upd = cbt->ins == NULL ? NULL : __wt_txn_read(session, cbt->ins->upd); if (upd == NULL) { cbt->v = __bit_getv_recno(page, cbt->recno, btree->bitcnt); val->data = &cbt->v; } else val->data = WT_UPDATE_DATA(upd); val->size = 1; return (0); }
/* * __cursor_skip_prev -- * Move back one position in a skip list stack (aka "finger"). */ static inline int __cursor_skip_prev(WT_CURSOR_BTREE *cbt) { WT_INSERT *current, *ins; WT_ITEM key; WT_SESSION_IMPL *session; int i; session = (WT_SESSION_IMPL *)cbt->iface.session; restart: /* * If the search stack does not point at the current item, fill it in * with a search. */ while ((current = cbt->ins) != PREV_INS(cbt, 0)) { if (cbt->btree->type == BTREE_ROW) { key.data = WT_INSERT_KEY(current); key.size = WT_INSERT_KEY_SIZE(current); WT_RET(__wt_search_insert(session, cbt, &key)); } else cbt->ins = __col_insert_search(cbt->ins_head, cbt->ins_stack, cbt->next_stack, WT_INSERT_RECNO(current)); } /* * Find the first node up the search stack that does not move. * * The depth of the current item must be at least this level, since we * see it in that many levels of the stack. * * !!! Watch these loops carefully: they all rely on the value of i, * and the exit conditions to end up with the right values are * non-trivial. */ ins = NULL; /* -Wconditional-uninitialized */ for (i = 0; i < WT_SKIP_MAXDEPTH - 1; i++) if ((ins = PREV_INS(cbt, i + 1)) != current) break; /* * Find a starting point for the new search. That is either at the * non-moving node if we found a valid node, or the beginning of the * next list down that is not the current node. * * Since it is the beginning of a list, and we know the current node is * has a skip depth at least this high, any node we find must sort * before the current node. */ if (ins == NULL || ins == current) for (; i >= 0; i--) { cbt->ins_stack[i] = NULL; cbt->next_stack[i] = NULL; ins = cbt->ins_head->head[i]; if (ins != NULL && ins != current) break; } /* Walk any remaining levels until just before the current node. */ while (i >= 0) { /* * If we get to the end of a list without finding the current * item, we must have raced with an insert. Restart the search. */ if (ins == NULL) { cbt->ins_stack[0] = NULL; cbt->next_stack[0] = NULL; goto restart; } if (ins->next[i] != current) /* Stay at this level */ ins = ins->next[i]; else { /* Drop down a level */ cbt->ins_stack[i] = &ins->next[i]; cbt->next_stack[i] = ins->next[i]; --i; } } /* If we found a previous node, the next one must be current. */ if (cbt->ins_stack[0] != NULL && *cbt->ins_stack[0] != current) goto restart; cbt->ins = PREV_INS(cbt, 0); return (0); }
/* * __wt_col_append_serial_func -- * Server function to append an WT_INSERT entry to the tree. */ int __wt_col_append_serial_func(WT_SESSION_IMPL *session, void *args) { WT_BTREE *btree; WT_INSERT *ins, *new_ins, ***ins_stack, **next_stack; WT_INSERT_HEAD *inshead, **insheadp, **new_inslist, *new_inshead; WT_PAGE *page; uint64_t recno; uint32_t write_gen; u_int i, skipdepth; btree = S2BT(session); __wt_col_append_unpack(args, &page, &write_gen, &insheadp, &ins_stack, &next_stack, &new_inslist, &new_inshead, &new_ins, &skipdepth); /* Check the page's write-generation. */ WT_RET(__wt_page_write_gen_check(session, page, write_gen)); if ((inshead = *insheadp) == NULL) inshead = new_inshead; /* * If the application specified a record number, there's a race: the * application may have searched for the record, not found it, then * called into the append code, and another thread might have added * the record. Fortunately, we're in the right place because if the * record didn't exist at some point, it can only have been created * on this list. Search for the record, if specified. */ if ((recno = WT_INSERT_RECNO(new_ins)) == 0) recno = WT_INSERT_RECNO(new_ins) = ++btree->last_recno; ins = __col_insert_search(inshead, ins_stack, next_stack, recno); /* If we find the record number, there's been a race. */ if (ins != NULL && WT_INSERT_RECNO(ins) == recno) WT_RET(WT_RESTART); /* * Publish: First, point the new WT_INSERT item's skiplist references * to the next elements in the insert list, then flush memory. Second, * update the skiplist elements that reference the new WT_INSERT item, * this ensures the list is never inconsistent. */ for (i = 0; i < skipdepth; i++) new_ins->next[i] = *ins_stack[i]; WT_WRITE_BARRIER(); for (i = 0; i < skipdepth; i++) { if (inshead->tail[i] == NULL || ins_stack[i] == &inshead->tail[i]->next[i]) inshead->tail[i] = new_ins; *ins_stack[i] = new_ins; } __wt_col_append_new_ins_taken(args); /* * If the insert head does not yet have an insert list, our caller * passed us one. * * NOTE: it is important to do this after the item has been added to * the list. Code can assume that if the list is set, it is non-empty. */ if (*insheadp == NULL) { WT_PUBLISH(*insheadp, new_inshead); __wt_col_append_new_inshead_taken(args); } /* * If the page does not yet have an insert array, our caller passed * us one. * * NOTE: it is important to do this after publishing the list entry. * Code can assume that if the array is set, it is non-empty. */ if (page->modify->append == NULL) { page->modify->append = new_inslist; __wt_col_append_new_inslist_taken(args); } /* * If we don't find the record, check to see if we extended the file, * and update the last record number. */ if (recno > btree->last_recno) btree->last_recno = recno; __wt_page_and_tree_modify_set(session, page); return (0); }
/* * __wt_col_modify -- * Column-store delete, insert, and update. */ int __wt_col_modify(WT_SESSION_IMPL *session, WT_CURSOR_BTREE *cbt, uint64_t recno, const WT_ITEM *value, WT_UPDATE *upd_arg, u_int modify_type, bool exclusive) { static const WT_ITEM col_fix_remove = { "", 1, NULL, 0, 0 }; WT_BTREE *btree; WT_DECL_RET; WT_INSERT *ins; WT_INSERT_HEAD *ins_head, **ins_headp; WT_PAGE *page; WT_PAGE_MODIFY *mod; WT_UPDATE *old_upd, *upd; size_t ins_size, upd_size; u_int i, skipdepth; bool append, logged; btree = cbt->btree; ins = NULL; page = cbt->ref->page; upd = upd_arg; append = logged = false; if (upd_arg == NULL) { if (modify_type == WT_UPDATE_RESERVE || modify_type == WT_UPDATE_TOMBSTONE) { /* * Fixed-size column-store doesn't have on-page deleted * values, it's a nul byte. */ if (modify_type == WT_UPDATE_TOMBSTONE && btree->type == BTREE_COL_FIX) { modify_type = WT_UPDATE_STANDARD; value = &col_fix_remove; } } /* * There's a chance the application specified a record past the * last record on the page. If that's the case and we're * inserting a new WT_INSERT/WT_UPDATE pair, it goes on the * append list, not the update list. Also, an out-of-band recno * implies an append operation, we're allocating a new row. * Ignore any information obtained from the search. */ WT_ASSERT(session, recno != WT_RECNO_OOB || cbt->compare != 0); if (cbt->compare != 0 && (recno == WT_RECNO_OOB || recno > (btree->type == BTREE_COL_VAR ? __col_var_last_recno(cbt->ref) : __col_fix_last_recno(cbt->ref)))) { append = true; cbt->ins = NULL; cbt->ins_head = NULL; } } /* We're going to modify the page, we should have loaded history. */ WT_ASSERT(session, cbt->ref->state != WT_REF_LIMBO); /* If we don't yet have a modify structure, we'll need one. */ WT_RET(__wt_page_modify_init(session, page)); mod = page->modify; /* * If modifying a record not previously modified, but which is in the * same update slot as a previously modified record, cursor.ins will * not be set because there's no list of update records for this recno, * but cursor.ins_head will be set to point to the correct update slot. * Acquire the necessary insert information, then create a new update * entry and link it into the existing list. We get here if a page has * a single cell representing multiple records (the records have the * same value), and then a record in the cell is updated or removed, * creating the update list for the cell, and then a cursor iterates * into that same cell to update/remove a different record. We find the * correct slot in the update array, but we don't find an update list * (because it doesn't exist), and don't have the information we need * to do the insert. Normally, we wouldn't care (we could fail and do * a search for the record which would configure everything for the * insert), but range truncation does this pattern for every record in * the cell, and the performance is terrible. For that reason, catch it * here. */ if (cbt->ins == NULL && cbt->ins_head != NULL) { cbt->ins = __col_insert_search( cbt->ins_head, cbt->ins_stack, cbt->next_stack, recno); if (cbt->ins != NULL) { if (WT_INSERT_RECNO(cbt->ins) == recno) cbt->compare = 0; else { /* * The test below is for cursor.compare set to 0 * and cursor.ins set: cursor.compare wasn't set * by the search we just did, and has an unknown * value. Clear cursor.ins to avoid the test. */ cbt->ins = NULL; } } } /* * Delete, insert or update a column-store entry. * * If modifying a previously modified record, cursor.ins will be set to * point to the correct update list. Create a new update entry and link * it into the existing list. * * Else, allocate an insert array as necessary, build an insert/update * structure pair, and link it into place. */ if (cbt->compare == 0 && cbt->ins != NULL) { /* * If we are restoring updates that couldn't be evicted, the * key must not exist on the new page. */ WT_ASSERT(session, upd_arg == NULL); /* Make sure the update can proceed. */ WT_ERR(__wt_txn_update_check(session, old_upd = cbt->ins->upd)); /* Allocate a WT_UPDATE structure and transaction ID. */ WT_ERR(__wt_update_alloc(session, value, &upd, &upd_size, modify_type)); WT_ERR(__wt_txn_modify(session, upd)); logged = true; /* Avoid a data copy in WT_CURSOR.update. */ cbt->modify_update = upd; /* * Point the new WT_UPDATE item to the next element in the list. * If we get it right, the serialization function lock acts as * our memory barrier to flush this write. */ upd->next = old_upd; /* Serialize the update. */ WT_ERR(__wt_update_serial( session, page, &cbt->ins->upd, &upd, upd_size, false)); } else { /* Allocate the append/update list reference as necessary. */ if (append) { WT_PAGE_ALLOC_AND_SWAP(session, page, mod->mod_col_append, ins_headp, 1); ins_headp = &mod->mod_col_append[0]; } else if (page->type == WT_PAGE_COL_FIX) { WT_PAGE_ALLOC_AND_SWAP(session, page, mod->mod_col_update, ins_headp, 1); ins_headp = &mod->mod_col_update[0]; } else { WT_PAGE_ALLOC_AND_SWAP(session, page, mod->mod_col_update, ins_headp, page->entries); ins_headp = &mod->mod_col_update[cbt->slot]; } /* Allocate the WT_INSERT_HEAD structure as necessary. */ WT_PAGE_ALLOC_AND_SWAP(session, page, *ins_headp, ins_head, 1); ins_head = *ins_headp; /* Choose a skiplist depth for this insert. */ skipdepth = __wt_skip_choose_depth(session); /* * Allocate a WT_INSERT/WT_UPDATE pair and transaction ID, and * update the cursor to reference it (the WT_INSERT_HEAD might * be allocated, the WT_INSERT was allocated). */ WT_ERR(__col_insert_alloc( session, recno, skipdepth, &ins, &ins_size)); cbt->ins_head = ins_head; cbt->ins = ins; /* * Check for insert split and checkpoint races in column-store: * it's easy (as opposed to in row-store) and a difficult bug to * otherwise diagnose. */ WT_ASSERT(session, mod->mod_col_split_recno == WT_RECNO_OOB || (recno != WT_RECNO_OOB && mod->mod_col_split_recno > recno)); if (upd_arg == NULL) { WT_ERR(__wt_update_alloc(session, value, &upd, &upd_size, modify_type)); WT_ERR(__wt_txn_modify(session, upd)); logged = true; /* Avoid a data copy in WT_CURSOR.update. */ cbt->modify_update = upd; } else upd_size = __wt_update_list_memsize(upd); ins->upd = upd; ins_size += upd_size; /* * If there was no insert list during the search, or there was * no search because the record number has not been allocated * yet, the cursor's information cannot be correct, search * couldn't have initialized it. * * Otherwise, point the new WT_INSERT item's skiplist to the * next elements in the insert list (which we will check are * still valid inside the serialization function). * * The serial mutex acts as our memory barrier to flush these * writes before inserting them into the list. */ if (cbt->ins_stack[0] == NULL || recno == WT_RECNO_OOB) for (i = 0; i < skipdepth; i++) { cbt->ins_stack[i] = &ins_head->head[i]; ins->next[i] = cbt->next_stack[i] = NULL; } else for (i = 0; i < skipdepth; i++) ins->next[i] = cbt->next_stack[i]; /* Append or insert the WT_INSERT structure. */ if (append) WT_ERR(__wt_col_append_serial( session, page, cbt->ins_head, cbt->ins_stack, &ins, ins_size, &cbt->recno, skipdepth, exclusive)); else WT_ERR(__wt_insert_serial( session, page, cbt->ins_head, cbt->ins_stack, &ins, ins_size, skipdepth, exclusive)); } /* If the update was successful, add it to the in-memory log. */ if (logged && modify_type != WT_UPDATE_RESERVE) { WT_ERR(__wt_txn_log_op(session, cbt)); /* * In case of append, the recno (key) for the value is assigned * now. Set the recno in the transaction operation to be used * incase this transaction is prepared to retrieve the update * corresponding to this operation. */ __wt_txn_op_set_recno(session, cbt->recno); } if (0) { err: /* * Remove the update from the current transaction, so we don't * try to modify it on rollback. */ if (logged) __wt_txn_unmodify(session); __wt_free(session, ins); if (upd_arg == NULL) __wt_free(session, upd); } return (ret); }