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/*-
* Copyright (c) 2014-2015 MongoDB, Inc.
* Copyright (c) 2008-2014 WiredTiger, Inc.
* All rights reserved.
*
* See the file LICENSE for redistribution information.
*/
#include "wt_internal.h"
/*
* __wt_evict_file --
* Discard pages for a specific file.
*/
int
__wt_evict_file(WT_SESSION_IMPL *session, int syncop)
{
WT_BTREE *btree;
WT_DECL_RET;
WT_PAGE *page;
WT_REF *next_ref, *ref;
int eviction_enabled;
btree = S2BT(session);
eviction_enabled = !F_ISSET(btree, WT_BTREE_NO_EVICTION);
/*
* We need exclusive access to the file -- disable ordinary eviction
* and drain any blocks already queued.
*/
if (eviction_enabled)
WT_RET(__wt_evict_file_exclusive_on(session));
/* Make sure the oldest transaction ID is up-to-date. */
__wt_txn_update_oldest(session);
/* Walk the tree, discarding pages. */
next_ref = NULL;
WT_ERR(__wt_tree_walk(
session, &next_ref, WT_READ_CACHE | WT_READ_NO_EVICT));
while ((ref = next_ref) != NULL) {
page = ref->page;
/*
* Eviction can fail when a page in the evicted page's subtree
* switches state. For example, if we don't evict a page marked
* empty, because we expect it to be merged into its parent, it
* might no longer be empty after it's reconciled, in which case
* eviction of its parent would fail. We can either walk the
* tree multiple times (until it's finally empty), or reconcile
* each page to get it to its final state before considering if
* it's an eviction target or will be merged into its parent.
*
* Don't limit this test to any particular page type, that tends
* to introduce bugs when the reconciliation of other page types
* changes, and there's no advantage to doing so.
*
* Eviction can also fail because an update cannot be written.
* If sessions have disjoint sets of files open, updates in a
* no-longer-referenced file may not yet be globally visible,
* and the write will fail with EBUSY. Our caller handles that
* error, retrying later.
*/
if (syncop == WT_SYNC_CLOSE && __wt_page_is_modified(page))
WT_ERR(__wt_reconcile(session, ref, NULL, WT_EVICTING));
/*
* We can't evict the page just returned to us (it marks our
* place in the tree), so move the walk to one page ahead of
* the page being evicted. Note, we reconciled the returned
* page first: if reconciliation of that page were to change
* the shape of the tree, and we did the next walk call before
* the reconciliation, the next walk call could miss a page in
* the tree.
*/
WT_ERR(__wt_tree_walk(
session, &next_ref, WT_READ_CACHE | WT_READ_NO_EVICT));
switch (syncop) {
case WT_SYNC_CLOSE:
/*
* Evict the page.
* Do not attempt to evict pages expected to be merged
* into their parents, with the exception that the root
* page can't be merged, it must be written.
*/
if (__wt_ref_is_root(ref) ||
page->modify == NULL ||
!F_ISSET(page->modify, WT_PM_REC_EMPTY))
WT_ERR(__wt_evict(session, ref, 1));
break;
case WT_SYNC_DISCARD:
/*
* Ordinary discard of the page, whether clean or dirty.
* If we see a dirty page in an ordinary discard (e.g.,
* from sweep), give up: an update must have happened
* since the file was selected for sweeping.
*/
if (__wt_page_is_modified(page))
WT_ERR(EBUSY);
/*
* If the page contains an update that is too recent to
* evict, stop. This should never happen during
* connection close, but in other paths our caller
* should be prepared to deal with this case.
*/
if (page->modify != NULL &&
!__wt_txn_visible_all(session,
page->modify->rec_max_txn))
WT_ERR(EBUSY);
__wt_evict_page_clean_update(session, ref);
break;
case WT_SYNC_DISCARD_FORCE:
/*
* Forced discard of the page, whether clean or dirty.
* If we see a dirty page in a forced discard, clean
* the page, both to keep statistics correct, and to
* let the page-discard function assert no dirty page
* is ever discarded.
*/
if (__wt_page_is_modified(page)) {
page->modify->write_gen = 0;
__wt_cache_dirty_decr(session, page);
}
F_SET(session, WT_SESSION_DISCARD_FORCE);
__wt_evict_page_clean_update(session, ref);
F_CLR(session, WT_SESSION_DISCARD_FORCE);
break;
WT_ILLEGAL_VALUE_ERR(session);
}
}
if (0) {
err: /* On error, clear any left-over tree walk. */
if (next_ref != NULL)
WT_TRET(__wt_page_release(
session, next_ref, WT_READ_NO_EVICT));
}
if (eviction_enabled)
__wt_evict_file_exclusive_off(session);
return (ret);
}
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