/*
* __wt_las_cursor --
* Return a lookaside cursor.
*/
int
__wt_las_cursor(
WT_SESSION_IMPL *session, WT_CURSOR **cursorp, uint32_t *session_flags)
{
WT_CONNECTION_IMPL *conn;
WT_DECL_RET;
*cursorp = NULL;
/*
* We don't want to get tapped for eviction after we start using the
* lookaside cursor; save a copy of the current eviction state, we'll
* turn eviction off before we return.
*
* Don't cache lookaside table pages, we're here because of eviction
* problems and there's no reason to believe lookaside pages will be
* useful more than once.
*/
*session_flags =
F_ISSET(session, WT_SESSION_NO_CACHE | WT_SESSION_NO_EVICTION);
conn = S2C(session);
/* Eviction and sweep threads have their own lookaside table cursors. */
if (F_ISSET(session, WT_SESSION_LOOKASIDE_CURSOR)) {
if (session->las_cursor == NULL) {
WT_WITHOUT_DHANDLE(session, ret =
__las_cursor_create(session, &session->las_cursor));
WT_RET(ret);
}
*cursorp = session->las_cursor;
} else {
/* Lock the shared lookaside cursor. */
__wt_spin_lock(session, &conn->las_lock);
*cursorp = conn->las_cursor;
}
/* Turn caching and eviction off. */
F_SET(session, WT_SESSION_NO_CACHE | WT_SESSION_NO_EVICTION);
return (0);
}
/*
* __wt_metadata_cursor_open --
* Opens a cursor on the metadata.
*/
int
__wt_metadata_cursor_open(
WT_SESSION_IMPL *session, const char *config, WT_CURSOR **cursorp)
{
WT_BTREE *btree;
WT_DECL_RET;
const char *open_cursor_cfg[] = {
WT_CONFIG_BASE(session, WT_SESSION_open_cursor), config, NULL };
WT_WITHOUT_DHANDLE(session, ret = __wt_open_cursor(
session, WT_METAFILE_URI, NULL, open_cursor_cfg, cursorp));
WT_RET(ret);
/*
* Retrieve the btree from the cursor, rather than the session because
* we don't always switch the metadata handle in to the session before
* entering this function.
*/
btree = ((WT_CURSOR_BTREE *)(*cursorp))->btree;
/*
* Special settings for metadata: skew eviction so metadata almost
* always stays in cache and make sure metadata is logged if possible.
*
* Test before setting so updates can't race in subsequent opens (the
* first update is safe because it's single-threaded from
* wiredtiger_open).
*/
if (btree->evict_priority == 0)
WT_WITH_BTREE(session, btree,
__wt_evict_priority_set(session, WT_EVICT_INT_SKEW));
if (F_ISSET(btree, WT_BTREE_NO_LOGGING))
F_CLR(btree, WT_BTREE_NO_LOGGING);
/* The metadata file always uses checkpoint IDs in visibility checks. */
btree->include_checkpoint_txn = true;
return (0);
}
/*
* __wt_metadata_cursor_open --
* Opens a cursor on the metadata.
*/
int
__wt_metadata_cursor_open(
WT_SESSION_IMPL *session, const char *config, WT_CURSOR **cursorp)
{
WT_BTREE *btree;
WT_DECL_RET;
const char *open_cursor_cfg[] = {
WT_CONFIG_BASE(session, WT_SESSION_open_cursor), config, NULL };
WT_WITHOUT_DHANDLE(session, ret = __wt_open_cursor(
session, WT_METAFILE_URI, NULL, open_cursor_cfg, cursorp));
WT_RET(ret);
/*
* Retrieve the btree from the cursor, rather than the session because
* we don't always switch the metadata handle in to the session before
* entering this function.
*/
btree = ((WT_CURSOR_BTREE *)(*cursorp))->btree;
/*
* Set special flags for the metadata file: eviction (the metadata file
* is in-memory and never evicted), logging (the metadata file is always
* logged if possible).
*
* Test flags before setting them so updates can't race in subsequent
* opens (the first update is safe because it's single-threaded from
* wiredtiger_open).
*/
if (!F_ISSET(btree, WT_BTREE_IN_MEMORY))
F_SET(btree, WT_BTREE_IN_MEMORY);
if (!F_ISSET(btree, WT_BTREE_NO_EVICTION))
F_SET(btree, WT_BTREE_NO_EVICTION);
if (F_ISSET(btree, WT_BTREE_NO_LOGGING))
F_CLR(btree, WT_BTREE_NO_LOGGING);
return (0);
}
/*
* __wt_las_create --
* Initialize the database's lookaside store.
*/
int
__wt_las_create(WT_SESSION_IMPL *session)
{
WT_CONNECTION_IMPL *conn;
WT_DECL_RET;
const char *drop_cfg[] = {
WT_CONFIG_BASE(session, WT_SESSION_drop), "force=true", NULL };
conn = S2C(session);
/*
* Done at startup: we cannot do it on demand because we require the
* schema lock to create and drop the file, and it may not always be
* available.
*
* Open an internal session, used for the shared lookaside cursor.
*
* Sessions associated with a lookaside cursor should never be tapped
* for eviction.
*/
WT_RET(__wt_open_internal_session(
conn, "lookaside table", 1, 1, &conn->las_session));
session = conn->las_session;
F_SET(session, WT_SESSION_LOOKASIDE_CURSOR | WT_SESSION_NO_EVICTION);
/* Discard any previous incarnation of the file. */
WT_RET(__wt_session_drop(session, WT_LAS_URI, drop_cfg));
/* Re-create the file. */
WT_RET(__wt_session_create(session, WT_LAS_URI, WT_LAS_FORMAT));
/* Open the shared cursor. */
WT_WITHOUT_DHANDLE(session,
ret = __las_cursor_create(session, &conn->las_cursor));
return (ret);
}
/*
* __wt_las_cursor_open --
* Open a new lookaside table cursor.
*/
int
__wt_las_cursor_open(WT_SESSION_IMPL *session, WT_CURSOR **cursorp)
{
WT_BTREE *btree;
WT_DECL_RET;
const char *open_cursor_cfg[] = {
WT_CONFIG_BASE(session, WT_SESSION_open_cursor), NULL };
WT_WITHOUT_DHANDLE(session, ret = __wt_open_cursor(
session, WT_LAS_URI, NULL, open_cursor_cfg, cursorp));
WT_RET(ret);
/*
* Retrieve the btree from the cursor, rather than the session because
* we don't always switch the LAS handle in to the session before
* entering this function.
*/
btree = ((WT_CURSOR_BTREE *)(*cursorp))->btree;
/*
* Set special flags for the lookaside table: the lookaside flag (used,
* for example, to avoid writing records during reconciliation), also
* turn off checkpoints and logging.
*
* Test flags before setting them so updates can't race in subsequent
* opens (the first update is safe because it's single-threaded from
* wiredtiger_open).
*/
if (!F_ISSET(btree, WT_BTREE_LOOKASIDE))
F_SET(btree, WT_BTREE_LOOKASIDE);
if (!F_ISSET(btree, WT_BTREE_NO_CHECKPOINT))
F_SET(btree, WT_BTREE_NO_CHECKPOINT);
if (!F_ISSET(btree, WT_BTREE_NO_LOGGING))
F_SET(btree, WT_BTREE_NO_LOGGING);
return (0);
}