/* * __wt_btcur_prev -- * Move to the previous record in the tree. */ int __wt_btcur_prev(WT_CURSOR_BTREE *cbt, bool truncating) { WT_DECL_RET; WT_PAGE *page; WT_SESSION_IMPL *session; uint32_t flags; bool newpage; session = (WT_SESSION_IMPL *)cbt->iface.session; WT_STAT_FAST_CONN_INCR(session, cursor_prev); WT_STAT_FAST_DATA_INCR(session, cursor_prev); flags = WT_READ_PREV | WT_READ_SKIP_INTL; /* Tree walk flags. */ if (truncating) LF_SET(WT_READ_TRUNCATE); WT_RET(__cursor_func_init(cbt, false)); /* * If we aren't already iterating in the right direction, there's * some setup to do. */ if (!F_ISSET(cbt, WT_CBT_ITERATE_PREV)) __wt_btcur_iterate_setup(cbt); /* * Walk any page we're holding until the underlying call returns not- * found. Then, move to the previous page, until we reach the start * of the file. */ for (newpage = false;; newpage = true) { page = cbt->ref == NULL ? NULL : cbt->ref->page; WT_ASSERT(session, page == NULL || !WT_PAGE_IS_INTERNAL(page)); /* * The last page in a column-store has appended entries. * We handle it separately from the usual cursor code: * it's only that one page and it's in a simple format. */ if (newpage && page != NULL && page->type != WT_PAGE_ROW_LEAF && (cbt->ins_head = WT_COL_APPEND(page)) != NULL) F_SET(cbt, WT_CBT_ITERATE_APPEND); if (F_ISSET(cbt, WT_CBT_ITERATE_APPEND)) { switch (page->type) { case WT_PAGE_COL_FIX: ret = __cursor_fix_append_prev(cbt, newpage); break; case WT_PAGE_COL_VAR: ret = __cursor_var_append_prev(cbt, newpage); break; WT_ILLEGAL_VALUE_ERR(session); } if (ret == 0) break; F_CLR(cbt, WT_CBT_ITERATE_APPEND); if (ret != WT_NOTFOUND) break; newpage = true; } if (page != NULL) { switch (page->type) { case WT_PAGE_COL_FIX: ret = __cursor_fix_prev(cbt, newpage); break; case WT_PAGE_COL_VAR: ret = __cursor_var_prev(cbt, newpage); break; case WT_PAGE_ROW_LEAF: ret = __cursor_row_prev(cbt, newpage); break; WT_ILLEGAL_VALUE_ERR(session); } if (ret != WT_NOTFOUND) break; } /* * If we saw a lot of deleted records on this page, or we went * all the way through a page and only saw deleted records, try * to evict the page when we release it. Otherwise repeatedly * deleting from the beginning of a tree can have quadratic * performance. Take care not to force eviction of pages that * are genuinely empty, in new trees. */ if (page != NULL && (cbt->page_deleted_count > WT_BTREE_DELETE_THRESHOLD || (newpage && cbt->page_deleted_count > 0))) __wt_page_evict_soon(page); cbt->page_deleted_count = 0; WT_ERR(__wt_tree_walk(session, &cbt->ref, flags)); WT_ERR_TEST(cbt->ref == NULL, WT_NOTFOUND); } err: if (ret != 0) WT_TRET(__cursor_reset(cbt)); return (ret); }
/* * __wt_btcur_prev -- * Move to the previous record in the tree. */ int __wt_btcur_prev(WT_CURSOR_BTREE *cbt, int discard) { WT_DECL_RET; WT_PAGE *page; WT_SESSION_IMPL *session; uint32_t flags; int newpage; session = (WT_SESSION_IMPL *)cbt->iface.session; WT_DSTAT_INCR(session, cursor_prev); flags = WT_TREE_SKIP_INTL | WT_TREE_PREV; /* Tree walk flags. */ if (discard) LF_SET(WT_TREE_DISCARD); retry: WT_RET(__cursor_func_init(cbt, 0)); __cursor_position_clear(cbt); /* * If we aren't already iterating in the right direction, there's * some setup to do. */ if (!F_ISSET(cbt, WT_CBT_ITERATE_PREV)) __wt_btcur_iterate_setup(cbt, 0); /* * If this is a modification, we're about to read information from the * page, save the write generation. */ page = cbt->page; if (discard && page != NULL) { WT_ERR(__wt_page_modify_init(session, page)); WT_ORDERED_READ(cbt->write_gen, page->modify->write_gen); } /* * Walk any page we're holding until the underlying call returns not- * found. Then, move to the previous page, until we reach the start * of the file. */ for (newpage = 0;; newpage = 1) { if (F_ISSET(cbt, WT_CBT_ITERATE_APPEND)) { switch (page->type) { case WT_PAGE_COL_FIX: ret = __cursor_fix_append_prev(cbt, newpage); break; case WT_PAGE_COL_VAR: ret = __cursor_var_append_prev(cbt, newpage); break; WT_ILLEGAL_VALUE_ERR(session); } if (ret == 0) break; F_CLR(cbt, WT_CBT_ITERATE_APPEND); if (ret != WT_NOTFOUND) break; newpage = 1; } if (page != NULL) { switch (page->type) { case WT_PAGE_COL_FIX: ret = __cursor_fix_prev(cbt, newpage); break; case WT_PAGE_COL_VAR: ret = __cursor_var_prev(cbt, newpage); break; case WT_PAGE_ROW_LEAF: ret = __cursor_row_prev(cbt, newpage); break; WT_ILLEGAL_VALUE_ERR(session); } if (ret != WT_NOTFOUND) break; } cbt->page = NULL; WT_ERR(__wt_tree_walk(session, &page, flags)); WT_ERR_TEST(page == NULL, WT_NOTFOUND); WT_ASSERT(session, page->type != WT_PAGE_COL_INT && page->type != WT_PAGE_ROW_INT); cbt->page = page; /* Initialize the page's modification information */ if (discard) { WT_ERR(__wt_page_modify_init(session, page)); WT_ORDERED_READ( cbt->write_gen, page->modify->write_gen); } /* * The last page in a column-store has appended entries. * We handle it separately from the usual cursor code: * it's only that one page and it's in a simple format. */ if (page->type != WT_PAGE_ROW_LEAF && (cbt->ins_head = WT_COL_APPEND(page)) != NULL) F_SET(cbt, WT_CBT_ITERATE_APPEND); } err: if (ret == WT_RESTART) goto retry; WT_TRET(__cursor_func_resolve(cbt, ret)); return (ret); }
/* * __wt_btcur_prev -- * Move to the previous record in the tree. */ int __wt_btcur_prev(WT_CURSOR_BTREE *cbt, int truncating) { WT_DECL_RET; WT_PAGE *page; WT_SESSION_IMPL *session; uint32_t flags; int newpage; session = (WT_SESSION_IMPL *)cbt->iface.session; WT_STAT_FAST_CONN_INCR(session, cursor_prev); WT_STAT_FAST_DATA_INCR(session, cursor_prev); flags = WT_READ_PREV | WT_READ_SKIP_INTL; /* Tree walk flags. */ if (truncating) LF_SET(WT_READ_TRUNCATE); WT_RET(__cursor_func_init(cbt, 0)); /* * If we aren't already iterating in the right direction, there's * some setup to do. */ if (!F_ISSET(cbt, WT_CBT_ITERATE_PREV)) __wt_btcur_iterate_setup(cbt, 0); /* * Walk any page we're holding until the underlying call returns not- * found. Then, move to the previous page, until we reach the start * of the file. */ page = cbt->ref == NULL ? NULL : cbt->ref->page; for (newpage = 0;; newpage = 1) { if (F_ISSET(cbt, WT_CBT_ITERATE_APPEND)) { switch (page->type) { case WT_PAGE_COL_FIX: ret = __cursor_fix_append_prev(cbt, newpage); break; case WT_PAGE_COL_VAR: ret = __cursor_var_append_prev(cbt, newpage); break; WT_ILLEGAL_VALUE_ERR(session); } if (ret == 0) break; F_CLR(cbt, WT_CBT_ITERATE_APPEND); if (ret != WT_NOTFOUND) break; newpage = 1; } if (page != NULL) { switch (page->type) { case WT_PAGE_COL_FIX: ret = __cursor_fix_prev(cbt, newpage); break; case WT_PAGE_COL_VAR: ret = __cursor_var_prev(cbt, newpage); break; case WT_PAGE_ROW_LEAF: ret = __cursor_row_prev(cbt, newpage); break; WT_ILLEGAL_VALUE_ERR(session); } if (ret != WT_NOTFOUND) break; } WT_ERR(__wt_tree_walk(session, &cbt->ref, flags)); WT_ERR_TEST(cbt->ref == NULL, WT_NOTFOUND); page = cbt->ref->page; WT_ASSERT(session, page->type != WT_PAGE_COL_INT && page->type != WT_PAGE_ROW_INT); /* * The last page in a column-store has appended entries. * We handle it separately from the usual cursor code: * it's only that one page and it's in a simple format. */ if (page->type != WT_PAGE_ROW_LEAF && (cbt->ins_head = WT_COL_APPEND(page)) != NULL) F_SET(cbt, WT_CBT_ITERATE_APPEND); } err: if (ret != 0) WT_TRET(__cursor_error_resolve(cbt)); return (ret); }
/* * __wt_btcur_prev -- * Move to the previous record in the tree. */ int __wt_btcur_prev(WT_CURSOR_BTREE *cbt) { WT_DECL_RET; WT_SESSION_IMPL *session; int newpage; session = (WT_SESSION_IMPL *)cbt->iface.session; WT_BSTAT_INCR(session, cursor_read_prev); __cursor_func_init(cbt, 0); /* * If we aren't already iterating in the right direction, there's * some setup to do. */ if (!F_ISSET(cbt, WT_CBT_ITERATE_PREV)) __wt_btcur_iterate_setup(cbt, 0); /* * Walk any page we're holding until the underlying call returns not- * found. Then, move to the previous page, until we reach the start * of the file. */ for (newpage = 0;; newpage = 1) { if (F_ISSET(cbt, WT_CBT_ITERATE_APPEND)) { switch (cbt->page->type) { case WT_PAGE_COL_FIX: ret = __cursor_fix_append_prev(cbt, newpage); break; case WT_PAGE_COL_VAR: ret = __cursor_var_append_prev(cbt, newpage); break; WT_ILLEGAL_VALUE_ERR(session); } if (ret == 0) break; F_CLR(cbt, WT_CBT_ITERATE_APPEND); if (ret != WT_NOTFOUND) break; newpage = 1; } if (cbt->page != NULL) { switch (cbt->page->type) { case WT_PAGE_COL_FIX: ret = __cursor_fix_prev(cbt, newpage); break; case WT_PAGE_COL_VAR: ret = __cursor_var_prev(cbt, newpage); break; case WT_PAGE_ROW_LEAF: ret = __cursor_row_prev(cbt, newpage); break; WT_ILLEGAL_VALUE_ERR(session); } if (ret != WT_NOTFOUND) break; } do { WT_ERR(__wt_tree_np(session, &cbt->page, 0, 0)); WT_ERR_TEST(cbt->page == NULL, WT_NOTFOUND); } while ( cbt->page->type == WT_PAGE_COL_INT || cbt->page->type == WT_PAGE_ROW_INT); /* * The last page in a column-store has appended entries. * We handle it separately from the usual cursor code: * it's only that one page and it's in a simple format. */ if (cbt->page->type != WT_PAGE_ROW_LEAF && (cbt->ins_head = WT_COL_APPEND(cbt->page)) != NULL) F_SET(cbt, WT_CBT_ITERATE_APPEND); } err: __cursor_func_resolve(cbt, ret); return (ret); }