path: root/src/third_party/wiredtiger/src/btree/col_modify.c

/*-
 * Copyright (c) 2014-2018 MongoDB, Inc.
 * Copyright (c) 2008-2014 WiredTiger, Inc.
 *	All rights reserved.
 *
 * See the file LICENSE for redistribution information.
 */

#include "wt_internal.h"

static int __col_insert_alloc(
    WT_SESSION_IMPL *, uint64_t, u_int, WT_INSERT **, size_t *);

/*
 * __wt_col_modify --
 *	Column-store delete, insert, and update.
 */
int
__wt_col_modify(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_SESSION_IMPL *session;
	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;
	session = (WT_SESSION_IMPL *)cbt->iface.session;
	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, cbt, 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, cbt, 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));

	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);
}

/*
 * __col_insert_alloc --
 *	Column-store insert: allocate a WT_INSERT structure and fill it in.
 */
static int
__col_insert_alloc(WT_SESSION_IMPL *session,
    uint64_t recno, u_int skipdepth, WT_INSERT **insp, size_t *ins_sizep)
{
	WT_INSERT *ins;
	size_t ins_size;

	/*
	 * Allocate the WT_INSERT structure and skiplist pointers, then copy
	 * the record number into place.
	 */
	ins_size = sizeof(WT_INSERT) + skipdepth * sizeof(WT_INSERT *);
	WT_RET(__wt_calloc(session, 1, ins_size, &ins));

	WT_INSERT_RECNO(ins) = recno;

	*insp = ins;
	*ins_sizep = ins_size;
	return (0);
}