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|
/*-
* Copyright (c) 2014-2019 MongoDB, Inc.
* Copyright (c) 2008-2014 WiredTiger, Inc.
* All rights reserved.
*
* See the file LICENSE for redistribution information.
*/
#include "wt_internal.h"
static void __rec_cleanup(WT_SESSION_IMPL *, WT_RECONCILE *);
static void __rec_destroy(WT_SESSION_IMPL *, void *);
static int __rec_destroy_session(WT_SESSION_IMPL *);
static int __rec_init(WT_SESSION_IMPL *, WT_REF *, uint32_t, WT_SALVAGE_COOKIE *, void *);
static int __rec_las_wrapup(WT_SESSION_IMPL *, WT_RECONCILE *);
static int __rec_las_wrapup_err(WT_SESSION_IMPL *, WT_RECONCILE *);
static int __rec_root_write(WT_SESSION_IMPL *, WT_PAGE *, uint32_t);
static int __rec_split_discard(WT_SESSION_IMPL *, WT_PAGE *);
static int __rec_split_row_promote(WT_SESSION_IMPL *, WT_RECONCILE *, WT_ITEM *, uint8_t);
static int __rec_split_write(WT_SESSION_IMPL *, WT_RECONCILE *, WT_REC_CHUNK *, WT_ITEM *, bool);
static int __rec_write_check_complete(WT_SESSION_IMPL *, WT_RECONCILE *, int, bool *);
static void __rec_write_page_status(WT_SESSION_IMPL *, WT_RECONCILE *);
static int __rec_write_wrapup(WT_SESSION_IMPL *, WT_RECONCILE *, WT_PAGE *);
static int __rec_write_wrapup_err(WT_SESSION_IMPL *, WT_RECONCILE *, WT_PAGE *);
static int __reconcile(WT_SESSION_IMPL *, WT_REF *, WT_SALVAGE_COOKIE *, uint32_t, bool *, bool *);
/*
* __wt_reconcile --
* Reconcile an in-memory page into its on-disk format, and write it.
*/
int
__wt_reconcile(WT_SESSION_IMPL *session, WT_REF *ref, WT_SALVAGE_COOKIE *salvage, uint32_t flags,
bool *lookaside_retryp)
{
WT_DECL_RET;
WT_PAGE *page;
bool no_reconcile_set, page_locked;
if (lookaside_retryp != NULL)
*lookaside_retryp = false;
page = ref->page;
__wt_verbose(session, WT_VERB_RECONCILE, "%p reconcile %s (%s%s%s)", (void *)ref,
__wt_page_type_string(page->type), LF_ISSET(WT_REC_EVICT) ? "evict" : "checkpoint",
LF_ISSET(WT_REC_LOOKASIDE) ? ", lookaside" : "",
LF_ISSET(WT_REC_UPDATE_RESTORE) ? ", update/restore" : "");
/*
* Sanity check flags.
*
* We can only do update/restore eviction when the version that ends up
* in the page image is the oldest one any reader could need.
* Otherwise we would need to keep updates in memory that go back older
* than the version in the disk image, and since modify operations
* aren't idempotent, that is problematic.
*
* If we try to do eviction using transaction visibility, we had better
* have a snapshot. This doesn't apply to checkpoints: there are
* (rare) cases where we write data at read-uncommitted isolation.
*/
WT_ASSERT(session, !LF_ISSET(WT_REC_LOOKASIDE) || !LF_ISSET(WT_REC_UPDATE_RESTORE));
WT_ASSERT(session, !LF_ISSET(WT_REC_UPDATE_RESTORE) || LF_ISSET(WT_REC_VISIBLE_ALL));
WT_ASSERT(session, !LF_ISSET(WT_REC_EVICT) || LF_ISSET(WT_REC_VISIBLE_ALL) ||
F_ISSET(&session->txn, WT_TXN_HAS_SNAPSHOT));
/* It's an error to be called with a clean page. */
WT_ASSERT(session, __wt_page_is_modified(page));
/*
* Reconciliation acquires and releases pages, and in rare cases that page release triggers
* eviction. If the page is dirty, eviction can trigger reconciliation, and we re-enter this
* code. Reconciliation isn't re-entrant, so we need to ensure that doesn't happen.
*/
no_reconcile_set = F_ISSET(session, WT_SESSION_NO_RECONCILE);
F_SET(session, WT_SESSION_NO_RECONCILE);
/*
* Reconciliation locks the page for three reasons:
* Reconciliation reads the lists of page updates, obsolete updates
* cannot be discarded while reconciliation is in progress;
* The compaction process reads page modification information, which
* reconciliation modifies;
* In-memory splits: reconciliation of an internal page cannot handle
* a child page splitting during the reconciliation.
*/
WT_PAGE_LOCK(session, page);
page_locked = true;
/*
* Now that the page is locked, if attempting to evict it, check again whether eviction is
* permitted. The page's state could have changed while we were waiting to acquire the lock
* (e.g., the page could have split).
*/
if (LF_ISSET(WT_REC_EVICT) && !__wt_page_can_evict(session, ref, NULL))
WT_ERR(__wt_set_return(session, EBUSY));
/*
* Reconcile the page. The reconciliation code unlocks the page as soon as possible, and returns
* that information.
*/
ret = __reconcile(session, ref, salvage, flags, lookaside_retryp, &page_locked);
err:
if (page_locked)
WT_PAGE_UNLOCK(session, page);
if (!no_reconcile_set)
F_CLR(session, WT_SESSION_NO_RECONCILE);
return (ret);
}
/*
* __reconcile_save_evict_state --
* Save the transaction state that causes history to be pinned, whether reconciliation succeeds
* or fails.
*/
static void
__reconcile_save_evict_state(WT_SESSION_IMPL *session, WT_REF *ref, uint32_t flags)
{
WT_PAGE_MODIFY *mod;
uint64_t oldest_id;
mod = ref->page->modify;
oldest_id = __wt_txn_oldest_id(session);
/*
* During eviction, save the transaction state that causes history to be pinned, regardless of
* whether reconciliation succeeds or fails. There is usually no point retrying eviction until
* this state changes.
*/
if (LF_ISSET(WT_REC_EVICT)) {
mod->last_eviction_id = oldest_id;
if (S2C(session)->txn_global.has_pinned_timestamp)
__wt_txn_pinned_timestamp(session, &mod->last_eviction_timestamp);
mod->last_evict_pass_gen = S2C(session)->cache->evict_pass_gen;
}
#ifdef HAVE_DIAGNOSTIC
/*
* Check that transaction time always moves forward for a given page. If this check fails,
* reconciliation can free something that a future reconciliation will need.
*/
WT_ASSERT(session, WT_TXNID_LE(mod->last_oldest_id, oldest_id));
mod->last_oldest_id = oldest_id;
#endif
}
/*
* __reconcile --
* Reconcile an in-memory page into its on-disk format, and write it.
*/
static int
__reconcile(WT_SESSION_IMPL *session, WT_REF *ref, WT_SALVAGE_COOKIE *salvage, uint32_t flags,
bool *lookaside_retryp, bool *page_lockedp)
{
WT_BTREE *btree;
WT_DECL_RET;
WT_PAGE *page;
WT_PAGE_MODIFY *mod;
WT_RECONCILE *r;
btree = S2BT(session);
page = ref->page;
mod = page->modify;
/* Save the eviction state. */
__reconcile_save_evict_state(session, ref, flags);
/* Initialize the reconciliation structure for each new run. */
WT_RET(__rec_init(session, ref, flags, salvage, &session->reconcile));
r = session->reconcile;
/* Reconcile the page. */
switch (page->type) {
case WT_PAGE_COL_FIX:
if (salvage != NULL)
ret = __wt_rec_col_fix_slvg(session, r, ref, salvage);
else
ret = __wt_rec_col_fix(session, r, ref);
break;
case WT_PAGE_COL_INT:
WT_WITH_PAGE_INDEX(session, ret = __wt_rec_col_int(session, r, ref));
break;
case WT_PAGE_COL_VAR:
ret = __wt_rec_col_var(session, r, ref, salvage);
break;
case WT_PAGE_ROW_INT:
WT_WITH_PAGE_INDEX(session, ret = __wt_rec_row_int(session, r, page));
break;
case WT_PAGE_ROW_LEAF:
ret = __wt_rec_row_leaf(session, r, ref, salvage);
break;
default:
ret = __wt_illegal_value(session, page->type);
break;
}
/*
* Update the global lookaside score. Only use observations during eviction, not checkpoints and
* don't count eviction of the lookaside table itself.
*/
if (F_ISSET(r, WT_REC_EVICT) && !F_ISSET(btree, WT_BTREE_LOOKASIDE))
__wt_cache_update_lookaside_score(session, r->updates_seen, r->updates_unstable);
/* Check for a successful reconciliation. */
WT_TRET(__rec_write_check_complete(session, r, ret, lookaside_retryp));
/* Wrap up the page reconciliation. */
if (ret == 0 && (ret = __rec_write_wrapup(session, r, page)) == 0)
__rec_write_page_status(session, r);
else
WT_TRET(__rec_write_wrapup_err(session, r, page));
/*
* If reconciliation completes successfully, save the stable timestamp.
*/
if (ret == 0 && S2C(session)->txn_global.has_stable_timestamp)
mod->last_stable_timestamp = S2C(session)->txn_global.stable_timestamp;
/* Release the reconciliation lock. */
*page_lockedp = false;
WT_PAGE_UNLOCK(session, page);
/* Update statistics. */
WT_STAT_CONN_INCR(session, rec_pages);
WT_STAT_DATA_INCR(session, rec_pages);
if (LF_ISSET(WT_REC_EVICT)) {
WT_STAT_CONN_INCR(session, rec_pages_eviction);
WT_STAT_DATA_INCR(session, rec_pages_eviction);
}
if (r->cache_write_lookaside) {
WT_STAT_CONN_INCR(session, cache_write_lookaside);
WT_STAT_DATA_INCR(session, cache_write_lookaside);
}
if (r->cache_write_restore) {
WT_STAT_CONN_INCR(session, cache_write_restore);
WT_STAT_DATA_INCR(session, cache_write_restore);
}
if (r->multi_next > btree->rec_multiblock_max)
btree->rec_multiblock_max = r->multi_next;
/* Clean up the reconciliation structure. */
__rec_cleanup(session, r);
/*
* When threads perform eviction, don't cache block manager structures
* (even across calls), we can have a significant number of threads
* doing eviction at the same time with large items. Ignore checkpoints,
* once the checkpoint completes, all unnecessary session resources will
* be discarded.
*/
if (!WT_SESSION_IS_CHECKPOINT(session)) {
/*
* Clean up the underlying block manager memory too: it's not reconciliation, but threads
* discarding reconciliation structures want to clean up the block manager's structures as
* well, and there's no obvious place to do that.
*/
if (session->block_manager_cleanup != NULL)
WT_TRET(session->block_manager_cleanup(session));
WT_TRET(__rec_destroy_session(session));
}
/*
* We track removed overflow objects in case there's a reader in transit when they're removed.
* Any form of eviction locks out readers, we can discard them all.
*/
if (LF_ISSET(WT_REC_EVICT))
__wt_ovfl_discard_remove(session, page);
WT_RET(ret);
/*
* Root pages are special, splits have to be done, we can't put it off as the parent's problem
* any more.
*/
if (__wt_ref_is_root(ref)) {
WT_WITH_PAGE_INDEX(session, ret = __rec_root_write(session, page, flags));
return (ret);
}
/*
* Otherwise, mark the page's parent dirty. Don't mark the tree dirty: if this reconciliation is
* in service of a checkpoint, it's cleared the tree's dirty flag, and we don't want to set it
* again as part of that walk.
*/
return (__wt_page_parent_modify_set(session, ref, true));
}
/*
* __rec_write_check_complete --
* Check that reconciliation should complete.
*/
static int
__rec_write_check_complete(
WT_SESSION_IMPL *session, WT_RECONCILE *r, int tret, bool *lookaside_retryp)
{
/*
* Tests in this function are lookaside tests and tests to decide if rewriting a page in memory
* is worth doing. In-memory configurations can't use a lookaside table, and we ignore page
* rewrite desirability checks for in-memory eviction because a small cache can force us to
* rewrite every possible page.
*/
if (F_ISSET(r, WT_REC_IN_MEMORY))
return (0);
/*
* Fall back to lookaside eviction during checkpoints if a page can't be evicted.
*/
if (tret == EBUSY && lookaside_retryp != NULL && !F_ISSET(r, WT_REC_UPDATE_RESTORE) &&
!r->update_uncommitted)
*lookaside_retryp = true;
/* Don't continue if we have already given up. */
WT_RET(tret);
/*
* Check if this reconciliation attempt is making progress. If there's any sign of progress,
* don't fall back to the lookaside table.
*
* Check if the current reconciliation split, in which case we'll likely get to write at least
* one of the blocks. If we've created a page image for a page that previously didn't have one,
* or we had a page image and it is now empty, that's also progress.
*/
if (r->multi_next > 1)
return (0);
/*
* We only suggest lookaside if currently in an evict/restore attempt and some updates were
* saved. Our caller sets the evict/restore flag based on various conditions (like if this is a
* leaf page), which is why we're testing that flag instead of a set of other conditions. If no
* updates were saved, eviction will succeed without needing to restore anything.
*/
if (!F_ISSET(r, WT_REC_UPDATE_RESTORE) || lookaside_retryp == NULL ||
(r->multi_next == 1 && r->multi->supd_entries == 0))
return (0);
/*
* Check if the current reconciliation applied some updates, in which case evict/restore should
* gain us some space.
*
* Check if lookaside eviction is possible. If any of the updates we saw were uncommitted, the
* lookaside table cannot be used.
*/
if (r->update_uncommitted || r->update_used)
return (0);
*lookaside_retryp = true;
return (__wt_set_return(session, EBUSY));
}
/*
* __rec_write_page_status --
* Set the page status after reconciliation.
*/
static void
__rec_write_page_status(WT_SESSION_IMPL *session, WT_RECONCILE *r)
{
WT_BTREE *btree;
WT_PAGE *page;
WT_PAGE_MODIFY *mod;
btree = S2BT(session);
page = r->page;
mod = page->modify;
/*
* Set the page's status based on whether or not we cleaned the page.
*/
if (r->leave_dirty) {
/*
* The page remains dirty.
*
* Any checkpoint call cleared the tree's modified flag before writing pages, so we must
* explicitly reset it. We insert a barrier after the change for clarity (the requirement is
* the flag be set before a subsequent checkpoint reads it, and as the current checkpoint is
* waiting on this reconciliation to complete, there's no risk of that happening).
*/
btree->modified = true;
WT_FULL_BARRIER();
if (!S2C(session)->modified)
S2C(session)->modified = true;
/*
* Eviction should only be here if following the save/restore eviction path.
*/
WT_ASSERT(session,
!F_ISSET(r, WT_REC_EVICT) || F_ISSET(r, WT_REC_LOOKASIDE | WT_REC_UPDATE_RESTORE));
/*
* We have written the page, but something prevents it from being evicted. If we wrote the
* newest versions of updates, the on-disk page may contain records that are newer than what
* checkpoint would write. Make sure that checkpoint visits the page and (if necessary)
* fixes things up.
*/
if (r->las_skew_newest)
mod->first_dirty_txn = WT_TXN_FIRST;
} else {
/*
* Track the page's maximum transaction ID (used to decide if we can evict a clean page and
* discard its history).
*/
mod->rec_max_txn = r->max_txn;
mod->rec_max_timestamp = r->max_ts;
/*
* Track the tree's maximum transaction ID (used to decide if it's safe to discard the
* tree). Reconciliation for eviction is multi-threaded, only update the tree's maximum
* transaction ID when doing a checkpoint. That's sufficient, we only care about the maximum
* transaction ID of current updates in the tree, and checkpoint visits every dirty page in
* the tree.
*/
if (!F_ISSET(r, WT_REC_EVICT)) {
if (WT_TXNID_LT(btree->rec_max_txn, r->max_txn))
btree->rec_max_txn = r->max_txn;
if (btree->rec_max_timestamp < r->max_ts)
btree->rec_max_timestamp = r->max_ts;
}
/*
* We set the page state to mark it as having been dirtied for the first time prior to
* reconciliation. A failed atomic cas indicates that an update has taken place during
* reconciliation.
*
* The page only might be clean; if the page state is unchanged since reconciliation
* started, it's clean.
*
* If the page state changed, the page has been written since reconciliation started and
* remains dirty (that can't happen when evicting, the page is exclusively locked).
*/
if (__wt_atomic_cas32(&mod->page_state, WT_PAGE_DIRTY_FIRST, WT_PAGE_CLEAN))
__wt_cache_dirty_decr(session, page);
else
WT_ASSERT(session, !F_ISSET(r, WT_REC_EVICT));
}
}
/*
* __rec_root_write --
* Handle the write of a root page.
*/
static int
__rec_root_write(WT_SESSION_IMPL *session, WT_PAGE *page, uint32_t flags)
{
WT_DECL_RET;
WT_PAGE *next;
WT_PAGE_INDEX *pindex;
WT_PAGE_MODIFY *mod;
WT_REF fake_ref;
uint32_t i;
mod = page->modify;
/*
* If a single root page was written (either an empty page or there was a 1-for-1 page swap),
* we've written root and checkpoint, we're done. If the root page split, write the resulting
* WT_REF array. We already have an infrastructure for writing pages, create a fake root page
* and write it instead of adding code to write blocks based on the list of blocks resulting
* from a multiblock reconciliation.
*/
switch (mod->rec_result) {
case WT_PM_REC_EMPTY: /* Page is empty */
case WT_PM_REC_REPLACE: /* 1-for-1 page swap */
return (0);
case WT_PM_REC_MULTIBLOCK: /* Multiple blocks */
break;
default:
return (__wt_illegal_value(session, mod->rec_result));
}
__wt_verbose(
session, WT_VERB_SPLIT, "root page split -> %" PRIu32 " pages", mod->mod_multi_entries);
/*
* Create a new root page, initialize the array of child references, mark it dirty, then write
* it.
*
* Don't count the eviction of this page as progress, checkpoint can repeatedly create and
* discard these pages.
*/
WT_RET(__wt_page_alloc(session, page->type, mod->mod_multi_entries, false, &next));
F_SET_ATOMIC(next, WT_PAGE_EVICT_NO_PROGRESS);
WT_INTL_INDEX_GET(session, next, pindex);
for (i = 0; i < mod->mod_multi_entries; ++i) {
/*
* There's special error handling required when re-instantiating pages in memory; it's not
* needed here, asserted for safety.
*/
WT_ASSERT(session, mod->mod_multi[i].supd == NULL);
WT_ASSERT(session, mod->mod_multi[i].disk_image == NULL);
WT_ERR(
__wt_multi_to_ref(session, next, &mod->mod_multi[i], &pindex->index[i], NULL, false));
pindex->index[i]->home = next;
}
/*
* We maintain a list of pages written for the root in order to free the backing blocks the next
* time the root is written.
*/
mod->mod_root_split = next;
/*
* Mark the page dirty. Don't mark the tree dirty: if this reconciliation is in service of a
* checkpoint, it's cleared the tree's dirty flag, and we don't want to set it again as part of
* that walk.
*/
WT_ERR(__wt_page_modify_init(session, next));
__wt_page_only_modify_set(session, next);
/*
* Fake up a reference structure, and write the next root page.
*/
__wt_root_ref_init(session, &fake_ref, next, page->type == WT_PAGE_COL_INT);
return (__wt_reconcile(session, &fake_ref, NULL, flags, NULL));
err:
__wt_page_out(session, &next);
return (ret);
}
/*
* __rec_init --
* Initialize the reconciliation structure.
*/
static int
__rec_init(WT_SESSION_IMPL *session, WT_REF *ref, uint32_t flags, WT_SALVAGE_COOKIE *salvage,
void *reconcilep)
{
WT_BTREE *btree;
WT_DECL_RET;
WT_PAGE *page;
WT_RECONCILE *r;
WT_TXN_GLOBAL *txn_global;
btree = S2BT(session);
page = ref->page;
/*
* Reconciliation is not re-entrant, make sure that doesn't happen. Our caller sets
* WT_SESSION_IMPL.WT_SESSION_NO_RECONCILE to prevent it, but it's been a problem in the past,
* check to be sure.
*/
r = *(WT_RECONCILE **)reconcilep;
if (r != NULL && r->ref != NULL)
WT_RET_MSG(session, WT_ERROR, "reconciliation re-entered");
if (r == NULL) {
WT_RET(__wt_calloc_one(session, &r));
session->reconcile_cleanup = __rec_destroy_session;
/* Connect pointers/buffers. */
r->cur = &r->_cur;
r->last = &r->_last;
/* Disk buffers need to be aligned for writing. */
F_SET(&r->chunkA.image, WT_ITEM_ALIGNED);
F_SET(&r->chunkB.image, WT_ITEM_ALIGNED);
}
/* Remember the configuration. */
r->ref = ref;
r->page = page;
/*
* Save the transaction generations before reading the page. These are all ordered reads, but we
* only need one.
*/
r->orig_btree_checkpoint_gen = btree->checkpoint_gen;
r->orig_txn_checkpoint_gen = __wt_gen(session, WT_GEN_CHECKPOINT);
/*
* Update the page state to indicate that all currently installed updates will be included in
* this reconciliation if it would mark the page clean.
*
* Add a write barrier to make it more likely that a thread adding an update will see this state
* change.
*/
page->modify->page_state = WT_PAGE_DIRTY_FIRST;
WT_FULL_BARRIER();
/*
* Cache the oldest running transaction ID. This is used to check whether updates seen by
* reconciliation have committed. We keep a cached copy to avoid races where a concurrent
* transaction could abort while reconciliation is examining its updates. This way, any
* transaction running when reconciliation starts is considered uncommitted.
*/
txn_global = &S2C(session)->txn_global;
WT_ORDERED_READ(r->last_running, txn_global->last_running);
/*
* Decide whether to skew on-page values towards newer or older versions. This is a heuristic
* attempting to minimize the number of pages that need to be rewritten by future checkpoints.
*
* We usually prefer to skew to newer versions, the logic being that by the time the next
* checkpoint runs, it is likely that all the updates we choose will be stable. However, if
* checkpointing with a timestamp (indicated by a stable_timestamp being set), and there is a
* checkpoint already running, or this page was read with lookaside history, or the stable
* timestamp hasn't changed since last time this page was successfully, skew oldest instead.
*/
if (F_ISSET(S2C(session)->cache, WT_CACHE_EVICT_DEBUG_MODE) &&
__wt_random(&session->rnd) % 3 == 0)
r->las_skew_newest = false;
else
r->las_skew_newest = LF_ISSET(WT_REC_LOOKASIDE) && LF_ISSET(WT_REC_VISIBLE_ALL);
if (r->las_skew_newest && !__wt_btree_immediately_durable(session) &&
txn_global->has_stable_timestamp &&
((btree->checkpoint_gen != __wt_gen(session, WT_GEN_CHECKPOINT) &&
txn_global->stable_is_pinned) ||
FLD_ISSET(page->modify->restore_state, WT_PAGE_RS_LOOKASIDE) ||
page->modify->last_stable_timestamp == txn_global->stable_timestamp))
r->las_skew_newest = false;
/*
* When operating on the lookaside table, we should never try update/restore or lookaside
* eviction.
*/
WT_ASSERT(session,
!F_ISSET(btree, WT_BTREE_LOOKASIDE) || !LF_ISSET(WT_REC_LOOKASIDE | WT_REC_UPDATE_RESTORE));
/*
* Lookaside table eviction is configured when eviction gets aggressive,
* adjust the flags for cases we don't support.
*
* We don't yet support fixed-length column-store combined with the
* lookaside table. It's not hard to do, but the underlying function
* that reviews which updates can be written to the evicted page and
* which updates need to be written to the lookaside table needs access
* to the original value from the page being evicted, and there's no
* code path for that in the case of fixed-length column-store objects.
* (Row-store and variable-width column-store objects provide a
* reference to the unpacked on-page cell for this purpose, but there
* isn't an on-page cell for fixed-length column-store objects.) For
* now, turn it off.
*/
if (page->type == WT_PAGE_COL_FIX)
LF_CLR(WT_REC_LOOKASIDE);
r->flags = flags;
/* Track the page's min/maximum transaction */
r->max_txn = WT_TXN_NONE;
r->max_ondisk_ts = r->max_ts = WT_TS_NONE;
r->min_skipped_ts = WT_TS_MAX;
/* Track if updates were used and/or uncommitted. */
r->updates_seen = r->updates_unstable = 0;
r->update_uncommitted = r->update_used = false;
/* Track if all the updates are with prepare in-progress state. */
r->all_upd_prepare_in_prog = true;
/* Track if the page can be marked clean. */
r->leave_dirty = false;
/* Track overflow items. */
r->ovfl_items = false;
/* Track empty values. */
r->all_empty_value = true;
r->any_empty_value = false;
/* The list of saved updates is reused. */
r->supd_next = 0;
r->supd_memsize = 0;
/* The list of pages we've written. */
r->multi = NULL;
r->multi_next = 0;
r->multi_allocated = 0;
r->wrapup_checkpoint = NULL;
r->wrapup_checkpoint_compressed = false;
r->evict_matching_checksum_failed = false;
/*
* Dictionary compression only writes repeated values once. We grow the dictionary as necessary,
* always using the largest size we've seen.
*
* Reset the dictionary.
*
* Sanity check the size: 100 slots is the smallest dictionary we use.
*/
if (btree->dictionary != 0 && btree->dictionary > r->dictionary_slots)
WT_ERR(
__wt_rec_dictionary_init(session, r, btree->dictionary < 100 ? 100 : btree->dictionary));
__wt_rec_dictionary_reset(r);
/*
* Prefix compression discards repeated prefix bytes from row-store leaf page keys.
*/
r->key_pfx_compress_conf = false;
if (btree->prefix_compression && page->type == WT_PAGE_ROW_LEAF)
r->key_pfx_compress_conf = true;
/*
* Suffix compression shortens internal page keys by discarding trailing bytes that aren't
* necessary for tree navigation. We don't do suffix compression if there is a custom collator
* because we don't know what bytes a custom collator might use. Some custom collators (for
* example, a collator implementing reverse ordering of strings), won't have any problem with
* suffix compression: if there's ever a reason to implement suffix compression for custom
* collators, we can add a setting to the collator, configured when the collator is added, that
* turns on suffix compression.
*/
r->key_sfx_compress_conf = false;
if (btree->collator == NULL && btree->internal_key_truncate)
r->key_sfx_compress_conf = true;
r->is_bulk_load = false;
r->salvage = salvage;
r->cache_write_lookaside = r->cache_write_restore = false;
/*
* The fake cursor used to figure out modified update values points to the enclosing WT_REF as a
* way to access the page, and also needs to set the format.
*/
r->update_modify_cbt.ref = ref;
r->update_modify_cbt.iface.value_format = btree->value_format;
/*
* If we allocated the reconciliation structure and there was an error, clean up. If our caller
* passed in a structure, they own it.
*/
err:
if (*(WT_RECONCILE **)reconcilep == NULL) {
if (ret == 0)
*(WT_RECONCILE **)reconcilep = r;
else {
__rec_cleanup(session, r);
__rec_destroy(session, &r);
}
}
return (ret);
}
/*
* __rec_cleanup --
* Clean up after a reconciliation run, except for structures cached across runs.
*/
static void
__rec_cleanup(WT_SESSION_IMPL *session, WT_RECONCILE *r)
{
WT_BTREE *btree;
WT_MULTI *multi;
uint32_t i;
btree = S2BT(session);
if (btree->type == BTREE_ROW)
for (multi = r->multi, i = 0; i < r->multi_next; ++multi, ++i)
__wt_free(session, multi->key.ikey);
for (multi = r->multi, i = 0; i < r->multi_next; ++multi, ++i) {
__wt_free(session, multi->disk_image);
__wt_free(session, multi->supd);
__wt_free(session, multi->addr.addr);
}
__wt_free(session, r->multi);
/* Reconciliation is not re-entrant, make sure that doesn't happen. */
r->ref = NULL;
}
/*
* __rec_destroy --
* Clean up the reconciliation structure.
*/
static void
__rec_destroy(WT_SESSION_IMPL *session, void *reconcilep)
{
WT_RECONCILE *r;
if ((r = *(WT_RECONCILE **)reconcilep) == NULL)
return;
*(WT_RECONCILE **)reconcilep = NULL;
__wt_buf_free(session, &r->chunkA.key);
__wt_buf_free(session, &r->chunkA.min_key);
__wt_buf_free(session, &r->chunkA.image);
__wt_buf_free(session, &r->chunkB.key);
__wt_buf_free(session, &r->chunkB.min_key);
__wt_buf_free(session, &r->chunkB.image);
__wt_free(session, r->supd);
__wt_rec_dictionary_free(session, r);
__wt_buf_free(session, &r->k.buf);
__wt_buf_free(session, &r->v.buf);
__wt_buf_free(session, &r->_cur);
__wt_buf_free(session, &r->_last);
__wt_buf_free(session, &r->update_modify_cbt.iface.value);
__wt_free(session, r);
}
/*
* __rec_destroy_session --
* Clean up the reconciliation structure, session version.
*/
static int
__rec_destroy_session(WT_SESSION_IMPL *session)
{
__rec_destroy(session, &session->reconcile);
return (0);
}
/*
* __rec_leaf_page_max --
* Figure out the maximum leaf page size for the reconciliation.
*/
static inline uint32_t
__rec_leaf_page_max(WT_SESSION_IMPL *session, WT_RECONCILE *r)
{
WT_BTREE *btree;
WT_PAGE *page;
uint32_t page_size;
btree = S2BT(session);
page = r->page;
page_size = 0;
switch (page->type) {
case WT_PAGE_COL_FIX:
/*
* Column-store pages can grow if there are missing records
* (that is, we lost a chunk of the range, and have to write
* deleted records). Fixed-length objects are a problem, if
* there's a big missing range, we could theoretically have to
* write large numbers of missing objects.
*/
page_size = (uint32_t)WT_ALIGN(
WT_FIX_ENTRIES_TO_BYTES(btree, r->salvage->take + r->salvage->missing), btree->allocsize);
break;
case WT_PAGE_COL_VAR:
/*
* Column-store pages can grow if there are missing records
* (that is, we lost a chunk of the range, and have to write
* deleted records). Variable-length objects aren't usually a
* problem because we can write any number of deleted records
* in a single page entry because of the RLE, we just need to
* ensure that additional entry fits.
*/
break;
case WT_PAGE_ROW_LEAF:
default:
/*
* Row-store pages can't grow, salvage never does anything other than reduce the size of a
* page read from disk.
*/
break;
}
/*
* Default size for variable-length column-store and row-store pages during salvage is the
* maximum leaf page size.
*/
if (page_size < btree->maxleafpage)
page_size = btree->maxleafpage;
/*
* The page we read from the disk should be smaller than the page size we just calculated, check
* out of paranoia.
*/
if (page_size < page->dsk->mem_size)
page_size = page->dsk->mem_size;
/*
* Salvage is the backup plan: don't let this fail.
*/
return (page_size * 2);
}
/*
* __wt_split_page_size --
* Given a split percentage, calculate split page size in bytes.
*/
uint32_t
__wt_split_page_size(int split_pct, uint32_t maxpagesize, uint32_t allocsize)
{
uintmax_t a;
uint32_t split_size;
/*
* Ideally, the split page size is some percentage of the maximum page size rounded to an
* allocation unit (round to an allocation unit so we don't waste space when we write).
*/
a = maxpagesize; /* Don't overflow. */
split_size = (uint32_t)WT_ALIGN_NEAREST((a * (u_int)split_pct) / 100, allocsize);
/*
* Respect the configured split percentage if the calculated split size is either zero or a full
* page. The user has either configured an allocation size that matches the page size, or a
* split percentage that is close to zero or one hundred. Rounding is going to provide a worse
* outcome than having a split point that doesn't fall on an allocation size boundary in those
* cases.
*/
if (split_size == 0 || split_size == maxpagesize)
split_size = (uint32_t)((a * (u_int)split_pct) / 100);
return (split_size);
}
/*
* __rec_split_chunk_init --
* Initialize a single chunk structure.
*/
static int
__rec_split_chunk_init(WT_SESSION_IMPL *session, WT_RECONCILE *r, WT_REC_CHUNK *chunk)
{
chunk->recno = WT_RECNO_OOB;
/* Don't touch the key item memory, that memory is reused. */
chunk->key.size = 0;
chunk->entries = 0;
__wt_rec_addr_ts_init(r, &chunk->newest_durable_ts, &chunk->oldest_start_ts,
&chunk->oldest_start_txn, &chunk->newest_stop_ts, &chunk->newest_stop_txn);
chunk->min_recno = WT_RECNO_OOB;
/* Don't touch the key item memory, that memory is reused. */
chunk->min_key.size = 0;
chunk->min_entries = 0;
__wt_rec_addr_ts_init(r, &chunk->min_newest_durable_ts, &chunk->min_oldest_start_ts,
&chunk->min_oldest_start_txn, &chunk->min_newest_stop_ts, &chunk->min_newest_stop_txn);
chunk->min_offset = 0;
/*
* Allocate and clear the disk image buffer.
*
* Don't touch the disk image item memory, that memory is reused.
*
* Clear the disk page header to ensure all of it is initialized, even the unused fields.
*
* In the case of fixed-length column-store, clear the entire buffer: fixed-length column-store
* sets bits in bytes, where the bytes are assumed to initially be 0.
*/
WT_RET(__wt_buf_init(session, &chunk->image, r->disk_img_buf_size));
memset(chunk->image.mem, 0,
r->page->type == WT_PAGE_COL_FIX ? r->disk_img_buf_size : WT_PAGE_HEADER_SIZE);
return (0);
}
/*
* __wt_rec_split_init --
* Initialization for the reconciliation split functions.
*/
int
__wt_rec_split_init(
WT_SESSION_IMPL *session, WT_RECONCILE *r, WT_PAGE *page, uint64_t recno, uint64_t max)
{
WT_BM *bm;
WT_BTREE *btree;
WT_REC_CHUNK *chunk;
WT_REF *ref;
size_t corrected_page_size;
btree = S2BT(session);
bm = btree->bm;
/*
* The maximum leaf page size governs when an in-memory leaf page splits into multiple on-disk
* pages; however, salvage can't be allowed to split, there's no parent page yet. If we're doing
* salvage, override the caller's selection of a maximum page size, choosing a page size that
* ensures we won't split.
*/
if (r->salvage != NULL)
max = __rec_leaf_page_max(session, r);
/* Set the page sizes. */
r->page_size = (uint32_t)max;
/*
* If we have to split, we want to choose a smaller page size for the split pages, because
* otherwise we could end up splitting one large packed page over and over. We don't want to
* pick the minimum size either, because that penalizes an application that did a bulk load and
* subsequently inserted a few items into packed pages. Currently defaulted to 75%, but I have
* no empirical evidence that's "correct".
*
* The maximum page size may be a multiple of the split page size (for example, there's a
* maximum page size of 128KB, but because the table is active and we don't want to split a lot,
* the split size is 20KB). The maximum page size may NOT be an exact multiple of the split page
* size.
*
* It's lots of work to build these pages and don't want to start over when we reach the maximum
* page size (it's painful to restart after creating overflow items and compacted data, for
* example, as those items have already been written to disk). So, the loop calls the helper
* functions when approaching a split boundary, and we save the information at that point. We
* also save the boundary information at the minimum split size. We maintain two chunks (each
* boundary represents a chunk that gets written as a page) in the memory, writing out the older
* one to the disk as a page when we need to make space for a new chunk. On reaching the last
* chunk, if it turns out to be smaller than the minimum split size, we go back into the
* penultimate chunk and split at this minimum split size boundary. This moves some data from
* the penultimate chunk to the last chunk, hence increasing the size of the last page written
* without decreasing the penultimate page size beyond the minimum split size.
*
* Finally, all this doesn't matter for fixed-size column-store pages and salvage. Fixed-size
* column store pages can split under (very) rare circumstances, but they're allocated at a
* fixed page size, never anything smaller. In salvage, as noted above, we can't split at all.
*/
if (r->salvage != NULL) {
r->split_size = 0;
r->space_avail = r->page_size - WT_PAGE_HEADER_BYTE_SIZE(btree);
} else if (page->type == WT_PAGE_COL_FIX) {
r->split_size = r->page_size;
r->space_avail = r->split_size - WT_PAGE_HEADER_BYTE_SIZE(btree);
} else {
r->split_size = __wt_split_page_size(btree->split_pct, r->page_size, btree->allocsize);
r->space_avail = r->split_size - WT_PAGE_HEADER_BYTE_SIZE(btree);
r->min_split_size =
__wt_split_page_size(WT_BTREE_MIN_SPLIT_PCT, r->page_size, btree->allocsize);
r->min_space_avail = r->min_split_size - WT_PAGE_HEADER_BYTE_SIZE(btree);
}
/*
* Ensure the disk image buffer is large enough for the max object, as
* corrected by the underlying block manager.
*
* Since we want to support split_size values larger than the page size
* (to allow for adjustments based on the compression), this buffer
* should be the greater of split_size and page_size, then aligned to
* the next allocation size boundary. The latter shouldn't be an issue,
* but it's a possible scenario if, for example, the compression engine
* is expected to give us 5x compression and gives us nothing at all.
*/
corrected_page_size = r->page_size;
WT_RET(bm->write_size(bm, session, &corrected_page_size));
r->disk_img_buf_size = WT_ALIGN(WT_MAX(corrected_page_size, r->split_size), btree->allocsize);
/* Initialize the first split chunk. */
WT_RET(__rec_split_chunk_init(session, r, &r->chunkA));
r->cur_ptr = &r->chunkA;
r->prev_ptr = NULL;
/* Starting record number, entries, first free byte. */
r->recno = recno;
r->entries = 0;
r->first_free = WT_PAGE_HEADER_BYTE(btree, r->cur_ptr->image.mem);
/* New page, compression off. */
r->key_pfx_compress = r->key_sfx_compress = false;
/* Set the first chunk's key. */
chunk = r->cur_ptr;
if (btree->type == BTREE_ROW) {
ref = r->ref;
if (__wt_ref_is_root(ref))
WT_RET(__wt_buf_set(session, &chunk->key, "", 1));
else
__wt_ref_key(ref->home, ref, &chunk->key.data, &chunk->key.size);
} else
chunk->recno = recno;
return (0);
}
/*
* __rec_is_checkpoint --
* Return if we're writing a checkpoint.
*/
static bool
__rec_is_checkpoint(WT_SESSION_IMPL *session, WT_RECONCILE *r)
{
WT_BTREE *btree;
btree = S2BT(session);
/*
* Check to see if we're going to create a checkpoint.
*
* This function exists as a place to hang this comment.
*
* Any time we write the root page of the tree without splitting we are creating a checkpoint
* (and have to tell the underlying block manager so it creates and writes the additional
* information checkpoints require). However, checkpoints are completely consistent, and so we
* have to resolve information about the blocks we're expecting to free as part of the
* checkpoint, before writing the checkpoint. In short, we don't do checkpoint writes here;
* clear the boundary information as a reminder and create the checkpoint during wrapup.
*/
return (!F_ISSET(btree, WT_BTREE_NO_CHECKPOINT) && __wt_ref_is_root(r->ref));
}
/*
* __rec_split_row_promote --
* Key promotion for a row-store.
*/
static int
__rec_split_row_promote(WT_SESSION_IMPL *session, WT_RECONCILE *r, WT_ITEM *key, uint8_t type)
{
WT_BTREE *btree;
WT_DECL_ITEM(update);
WT_DECL_RET;
WT_ITEM *max;
WT_SAVE_UPD *supd;
size_t cnt, len, size;
uint32_t i;
const uint8_t *pa, *pb;
int cmp;
/*
* For a column-store, the promoted key is the recno and we already have a copy. For a
* row-store, it's the first key on the page, a variable- length byte string, get a copy.
*
* This function is called from the split code at each split boundary, but that means we're not
* called before the first boundary, and we will eventually have to get the first key explicitly
* when splitting a page.
*
* For the current slot, take the last key we built, after doing suffix compression. The "last
* key we built" describes some process: before calling the split code, we must place the last
* key on the page before the boundary into the "last" key structure, and the first key on the
* page after the boundary into the "current" key structure, we're going to compare them for
* suffix compression.
*
* Suffix compression is a hack to shorten keys on internal pages. We only need enough bytes in
* the promoted key to ensure searches go to the correct page: the promoted key has to be larger
* than the last key on the leaf page preceding it, but we don't need any more bytes than that.
* In other words, we can discard any suffix bytes not required to distinguish between the key
* being promoted and the last key on the leaf page preceding it. This can only be done for the
* first level of internal pages, you cannot repeat suffix truncation as you split up the tree,
* it loses too much information.
*
* Note #1: if the last key on the previous page was an overflow key, we don't have the
* in-memory key against which to compare, and don't try to do suffix compression. The code for
* that case turns suffix compression off for the next key, we don't have to deal with it here.
*/
if (type != WT_PAGE_ROW_LEAF || !r->key_sfx_compress)
return (__wt_buf_set(session, key, r->cur->data, r->cur->size));
btree = S2BT(session);
WT_RET(__wt_scr_alloc(session, 0, &update));
/*
* Note #2: if we skipped updates, an update key may be larger than the last key stored in the
* previous block (probable for append-centric workloads). If there are skipped updates, check
* for one larger than the last key and smaller than the current key.
*/
max = r->last;
if (F_ISSET(r, WT_REC_UPDATE_RESTORE))
for (i = r->supd_next; i > 0; --i) {
supd = &r->supd[i - 1];
if (supd->ins == NULL)
WT_ERR(__wt_row_leaf_key(session, r->page, supd->ripcip, update, false));
else {
update->data = WT_INSERT_KEY(supd->ins);
update->size = WT_INSERT_KEY_SIZE(supd->ins);
}
/* Compare against the current key, it must be less. */
WT_ERR(__wt_compare(session, btree->collator, update, r->cur, &cmp));
if (cmp >= 0)
continue;
/* Compare against the last key, it must be greater. */
WT_ERR(__wt_compare(session, btree->collator, update, r->last, &cmp));
if (cmp >= 0)
max = update;
/*
* The saved updates are in key-sort order so the entry we're looking for is either the
* last or the next-to- last one in the list. Once we've compared an entry against the
* last key on the page, we're done.
*/
break;
}
/*
* The largest key on the last block must sort before the current key, so we'll either find a
* larger byte value in the current key, or the current key will be a longer key, and the
* interesting byte is one past the length of the shorter key.
*/
pa = max->data;
pb = r->cur->data;
len = WT_MIN(max->size, r->cur->size);
size = len + 1;
for (cnt = 1; len > 0; ++cnt, --len, ++pa, ++pb)
if (*pa != *pb) {
if (size != cnt) {
WT_STAT_DATA_INCRV(session, rec_suffix_compression, size - cnt);
size = cnt;
}
break;
}
ret = __wt_buf_set(session, key, r->cur->data, size);
err:
__wt_scr_free(session, &update);
return (ret);
}
/*
* __rec_split_grow --
* Grow the split buffer.
*/
static int
__rec_split_grow(WT_SESSION_IMPL *session, WT_RECONCILE *r, size_t add_len)
{
WT_BM *bm;
WT_BTREE *btree;
size_t corrected_page_size, inuse;
btree = S2BT(session);
bm = btree->bm;
inuse = WT_PTRDIFF(r->first_free, r->cur_ptr->image.mem);
corrected_page_size = inuse + add_len;
WT_RET(bm->write_size(bm, session, &corrected_page_size));
WT_RET(__wt_buf_grow(session, &r->cur_ptr->image, corrected_page_size));
r->first_free = (uint8_t *)r->cur_ptr->image.mem + inuse;
WT_ASSERT(session, corrected_page_size >= inuse);
r->space_avail = corrected_page_size - inuse;
WT_ASSERT(session, r->space_avail >= add_len);
return (0);
}
/*
* __wt_rec_split --
* Handle the page reconciliation bookkeeping. (Did you know "bookkeeper" has 3 doubled letters
* in a row? Sweet-tooth does, too.)
*/
int
__wt_rec_split(WT_SESSION_IMPL *session, WT_RECONCILE *r, size_t next_len, bool forced)
{
WT_BTREE *btree;
WT_REC_CHUNK *tmp;
size_t inuse;
btree = S2BT(session);
/*
* We should never split during salvage, and we're about to drop core because there's no parent
* page.
*/
if (r->salvage != NULL)
WT_PANIC_RET(session, WT_PANIC, "%s page too large, attempted split during salvage",
__wt_page_type_string(r->page->type));
/*
* We can get here if the first key/value pair won't fit. Grow the buffer to contain the current
* item if we haven't already consumed a reasonable portion of a split chunk.
*/
inuse = WT_PTRDIFF(r->first_free, r->cur_ptr->image.mem);
if (!forced && inuse < r->split_size / 2 && !__wt_rec_need_split(r, 0))
goto done;
/* All page boundaries reset the dictionary. */
__wt_rec_dictionary_reset(r);
/* Set the entries, timestamps and size for the just finished chunk. */
r->cur_ptr->entries = r->entries;
r->cur_ptr->image.size = inuse;
/*
* Normally we keep two chunks in memory at a given time, and we write the previous chunk at
* each boundary, switching the previous and current check references. The exception is when
* doing a bulk load or a forced split, where we write out the chunks as we get them.
*/
if (r->is_bulk_load)
WT_RET(__rec_split_write(session, r, r->cur_ptr, NULL, false));
else {
if (r->prev_ptr != NULL)
WT_RET(__rec_split_write(session, r, r->prev_ptr, NULL, false));
if (forced) {
WT_RET(__rec_split_write(session, r, r->cur_ptr, NULL, false));
r->prev_ptr = NULL;
r->cur_ptr = &r->chunkA;
} else {
if (r->prev_ptr == NULL) {
WT_RET(__rec_split_chunk_init(session, r, &r->chunkB));
r->prev_ptr = &r->chunkB;
}
tmp = r->prev_ptr;
r->prev_ptr = r->cur_ptr;
r->cur_ptr = tmp;
}
}
/* Initialize the next chunk, including the key. */
WT_RET(__rec_split_chunk_init(session, r, r->cur_ptr));
r->cur_ptr->recno = r->recno;
if (btree->type == BTREE_ROW)
WT_RET(__rec_split_row_promote(session, r, &r->cur_ptr->key, r->page->type));
/* Reset tracking information. */
r->entries = 0;
r->first_free = WT_PAGE_HEADER_BYTE(btree, r->cur_ptr->image.mem);
/*
* Set the space available to another split-size and minimum split-size chunk.
*/
r->space_avail = r->split_size - WT_PAGE_HEADER_BYTE_SIZE(btree);
r->min_space_avail = r->min_split_size - WT_PAGE_HEADER_BYTE_SIZE(btree);
done:
/*
* Overflow values can be larger than the maximum page size but still be
* "on-page". If the next key/value pair is larger than space available
* after a split has happened (in other words, larger than the maximum
* page size), create a page sized to hold that one key/value pair. This
* generally splits the page into key/value pairs before a large object,
* the object, and key/value pairs after the object. It's possible other
* key/value pairs will also be aggregated onto the bigger page before
* or after, if the page happens to hold them, but it won't necessarily
* happen that way.
*/
if (r->space_avail < next_len)
WT_RET(__rec_split_grow(session, r, next_len));
return (0);
}
/*
* __wt_rec_split_crossing_bnd --
* Save the details for the minimum split size boundary or call for a split.
*/
int
__wt_rec_split_crossing_bnd(WT_SESSION_IMPL *session, WT_RECONCILE *r, size_t next_len, bool forced)
{
/*
* If crossing the minimum split size boundary, store the boundary details at the current
* location in the buffer. If we are crossing the split boundary at the same time, possible when
* the next record is large enough, just split at this point.
*/
if (!forced && WT_CROSSING_MIN_BND(r, next_len) && !WT_CROSSING_SPLIT_BND(r, next_len) &&
!__wt_rec_need_split(r, 0)) {
/*
* If the first record doesn't fit into the minimum split size, we end up here. Write the
* record without setting a boundary here. We will get the opportunity to setup a boundary
* before writing out the next record.
*/
if (r->entries == 0)
return (0);
r->cur_ptr->min_entries = r->entries;
r->cur_ptr->min_recno = r->recno;
if (S2BT(session)->type == BTREE_ROW)
WT_RET(__rec_split_row_promote(session, r, &r->cur_ptr->min_key, r->page->type));
r->cur_ptr->min_newest_durable_ts = r->cur_ptr->newest_durable_ts;
r->cur_ptr->min_oldest_start_ts = r->cur_ptr->oldest_start_ts;
r->cur_ptr->min_oldest_start_txn = r->cur_ptr->oldest_start_txn;
r->cur_ptr->min_newest_stop_ts = r->cur_ptr->newest_stop_ts;
r->cur_ptr->min_newest_stop_txn = r->cur_ptr->newest_stop_txn;
/* Assert we're not re-entering this code. */
WT_ASSERT(session, r->cur_ptr->min_offset == 0);
r->cur_ptr->min_offset = WT_PTRDIFF(r->first_free, r->cur_ptr->image.mem);
/* All page boundaries reset the dictionary. */
__wt_rec_dictionary_reset(r);
return (0);
}
/* We are crossing a split boundary */
return (__wt_rec_split(session, r, next_len, forced));
}
/*
* __rec_split_finish_process_prev --
* If the two split chunks together fit in a single page, merge them into one. If they do not
* fit in a single page but the last is smaller than the minimum desired, move some data from
* the penultimate chunk to the last chunk and write out the previous/penultimate. Finally,
* update the pointer to the current image buffer. After this function exits, we will have one
* (last) buffer in memory, pointed to by the current image pointer.
*/
static int
__rec_split_finish_process_prev(WT_SESSION_IMPL *session, WT_RECONCILE *r)
{
WT_BTREE *btree;
WT_PAGE_HEADER *dsk;
WT_REC_CHUNK *cur_ptr, *prev_ptr, *tmp;
size_t combined_size, len_to_move;
uint8_t *cur_dsk_start;
WT_ASSERT(session, r->prev_ptr != NULL);
btree = S2BT(session);
cur_ptr = r->cur_ptr;
prev_ptr = r->prev_ptr;
/*
* The sizes in the chunk include the header, so when calculating the combined size, be sure not
* to include the header twice.
*/
combined_size = prev_ptr->image.size + (cur_ptr->image.size - WT_PAGE_HEADER_BYTE_SIZE(btree));
if (combined_size <= r->page_size) {
/*
* We have two boundaries, but the data in the buffers can fit a single page. Merge the
* boundaries and create a single chunk.
*/
prev_ptr->entries += cur_ptr->entries;
prev_ptr->newest_durable_ts =
WT_MAX(prev_ptr->newest_durable_ts, cur_ptr->newest_durable_ts);
prev_ptr->oldest_start_ts = WT_MIN(prev_ptr->oldest_start_ts, cur_ptr->oldest_start_ts);
prev_ptr->oldest_start_txn = WT_MIN(prev_ptr->oldest_start_txn, cur_ptr->oldest_start_txn);
prev_ptr->newest_stop_ts = WT_MAX(prev_ptr->newest_stop_ts, cur_ptr->newest_stop_ts);
prev_ptr->newest_stop_txn = WT_MAX(prev_ptr->newest_stop_txn, cur_ptr->newest_stop_txn);
dsk = r->cur_ptr->image.mem;
memcpy((uint8_t *)r->prev_ptr->image.mem + prev_ptr->image.size,
WT_PAGE_HEADER_BYTE(btree, dsk), cur_ptr->image.size - WT_PAGE_HEADER_BYTE_SIZE(btree));
prev_ptr->image.size = combined_size;
/*
* At this point, there is only one disk image in the memory, the previous chunk. Update the
* current chunk to that chunk, discard the unused chunk.
*/
tmp = r->prev_ptr;
r->prev_ptr = r->cur_ptr;
r->cur_ptr = tmp;
return (__rec_split_chunk_init(session, r, r->prev_ptr));
}
if (prev_ptr->min_offset != 0 && cur_ptr->image.size < r->min_split_size) {
/*
* The last chunk, pointed to by the current image pointer, has less than the minimum data.
* Let's move any data more than the minimum from the previous image into the current.
*
* Grow the current buffer if it is not large enough.
*/
len_to_move = prev_ptr->image.size - prev_ptr->min_offset;
if (r->space_avail < len_to_move)
WT_RET(__rec_split_grow(session, r, len_to_move));
cur_dsk_start = WT_PAGE_HEADER_BYTE(btree, r->cur_ptr->image.mem);
/*
* Shift the contents of the current buffer to make space for the data that will be
* prepended into the current buffer. Copy the data from the previous buffer to the start of
* the current.
*/
memmove(cur_dsk_start + len_to_move, cur_dsk_start,
cur_ptr->image.size - WT_PAGE_HEADER_BYTE_SIZE(btree));
memcpy(
cur_dsk_start, (uint8_t *)r->prev_ptr->image.mem + prev_ptr->min_offset, len_to_move);
/* Update boundary information */
cur_ptr->entries += prev_ptr->entries - prev_ptr->min_entries;
cur_ptr->recno = prev_ptr->min_recno;
WT_RET(
__wt_buf_set(session, &cur_ptr->key, prev_ptr->min_key.data, prev_ptr->min_key.size));
cur_ptr->newest_durable_ts =
WT_MAX(prev_ptr->newest_durable_ts, cur_ptr->newest_durable_ts);
cur_ptr->oldest_start_ts = WT_MIN(prev_ptr->oldest_start_ts, cur_ptr->oldest_start_ts);
cur_ptr->oldest_start_txn = WT_MIN(prev_ptr->oldest_start_txn, cur_ptr->oldest_start_txn);
cur_ptr->newest_stop_ts = WT_MAX(prev_ptr->newest_stop_ts, cur_ptr->newest_stop_ts);
cur_ptr->newest_stop_txn = WT_MAX(prev_ptr->newest_stop_txn, cur_ptr->newest_stop_txn);
cur_ptr->image.size += len_to_move;
prev_ptr->entries = prev_ptr->min_entries;
prev_ptr->newest_durable_ts = prev_ptr->min_newest_durable_ts;
prev_ptr->oldest_start_ts = prev_ptr->min_oldest_start_ts;
prev_ptr->oldest_start_txn = prev_ptr->min_oldest_start_txn;
prev_ptr->newest_stop_ts = prev_ptr->min_newest_stop_ts;
prev_ptr->newest_stop_txn = prev_ptr->min_newest_stop_txn;
prev_ptr->image.size -= len_to_move;
}
/* Write out the previous image */
return (__rec_split_write(session, r, r->prev_ptr, NULL, false));
}
/*
* __wt_rec_split_finish --
* Finish processing a page.
*/
int
__wt_rec_split_finish(WT_SESSION_IMPL *session, WT_RECONCILE *r)
{
/*
* We're done reconciling, write the final page. We may arrive here with no entries to write if
* the page was entirely empty or if nothing on the page was visible to us.
*
* Pages with skipped or not-yet-globally visible updates aren't really empty; otherwise, the
* page is truly empty and we will merge it into its parent during the parent's reconciliation.
*/
if (r->entries == 0 && r->supd_next == 0)
return (0);
/* Set the number of entries and size for the just finished chunk. */
r->cur_ptr->entries = r->entries;
r->cur_ptr->image.size = WT_PTRDIFF32(r->first_free, r->cur_ptr->image.mem);
/* Potentially reconsider a previous chunk. */
if (r->prev_ptr != NULL)
WT_RET(__rec_split_finish_process_prev(session, r));
/* Write the remaining data/last page. */
return (__rec_split_write(session, r, r->cur_ptr, NULL, true));
}
/*
* __rec_supd_move --
* Move a saved WT_UPDATE list from the per-page cache to a specific block's list.
*/
static int
__rec_supd_move(WT_SESSION_IMPL *session, WT_MULTI *multi, WT_SAVE_UPD *supd, uint32_t n)
{
uint32_t i;
WT_RET(__wt_calloc_def(session, n, &multi->supd));
for (i = 0; i < n; ++i)
multi->supd[i] = *supd++;
multi->supd_entries = n;
return (0);
}
/*
* __rec_split_write_supd --
* Check if we've saved updates that belong to this block, and move any to the per-block
* structure.
*/
static int
__rec_split_write_supd(
WT_SESSION_IMPL *session, WT_RECONCILE *r, WT_REC_CHUNK *chunk, WT_MULTI *multi, bool last_block)
{
WT_BTREE *btree;
WT_DECL_ITEM(key);
WT_DECL_RET;
WT_PAGE *page;
WT_REC_CHUNK *next;
WT_SAVE_UPD *supd;
WT_UPDATE *upd;
uint32_t i, j;
int cmp;
/*
* Check if we've saved updates that belong to this block, and move any to the per-block
* structure.
*
* This code requires a key be filled in for the next block (or the last block flag be set, if
* there's no next block).
*
* The last block gets all remaining saved updates.
*/
if (last_block) {
WT_RET(__rec_supd_move(session, multi, r->supd, r->supd_next));
r->supd_next = 0;
r->supd_memsize = 0;
goto done;
}
/*
* Get the saved update's key and compare it with the block's key range. If the saved update
* list belongs with the block we're about to write, move it to the per-block memory. Check only
* to the first update that doesn't go with the block, they must be in sorted order.
*
* The other chunk will have the key for the next page, that's what we compare against.
*/
next = chunk == r->cur_ptr ? r->prev_ptr : r->cur_ptr;
page = r->page;
if (page->type == WT_PAGE_ROW_LEAF) {
btree = S2BT(session);
WT_RET(__wt_scr_alloc(session, 0, &key));
for (i = 0, supd = r->supd; i < r->supd_next; ++i, ++supd) {
if (supd->ins == NULL)
WT_ERR(__wt_row_leaf_key(session, page, supd->ripcip, key, false));
else {
key->data = WT_INSERT_KEY(supd->ins);
key->size = WT_INSERT_KEY_SIZE(supd->ins);
}
WT_ASSERT(session, next != NULL);
WT_ERR(__wt_compare(session, btree->collator, key, &next->key, &cmp));
if (cmp >= 0)
break;
}
} else
for (i = 0, supd = r->supd; i < r->supd_next; ++i, ++supd)
if (WT_INSERT_RECNO(supd->ins) >= next->recno)
break;
if (i != 0) {
WT_ERR(__rec_supd_move(session, multi, r->supd, i));
/*
* If there are updates that weren't moved to the block, shuffle them to the beginning of
* the cached list (we maintain the saved updates in sorted order, new saved updates must be
* appended to the list).
*/
r->supd_memsize = 0;
for (j = 0; i < r->supd_next; ++j, ++i) {
/* Account for the remaining update memory. */
if (r->supd[i].ins == NULL)
upd = page->modify->mod_row_update[page->type == WT_PAGE_ROW_LEAF ?
WT_ROW_SLOT(page, r->supd[i].ripcip) :
WT_COL_SLOT(page, r->supd[i].ripcip)];
else
upd = r->supd[i].ins->upd;
r->supd_memsize += __wt_update_list_memsize(upd);
r->supd[j] = r->supd[i];
}
r->supd_next = j;
}
done:
if (F_ISSET(r, WT_REC_LOOKASIDE)) {
/* Track the oldest lookaside timestamp seen so far. */
multi->page_las.max_txn = r->max_txn;
multi->page_las.max_ondisk_ts = r->max_ondisk_ts;
multi->page_las.min_skipped_ts = r->min_skipped_ts;
}
err:
__wt_scr_free(session, &key);
return (ret);
}
/*
* __rec_split_write_header --
* Initialize a disk page's header.
*/
static void
__rec_split_write_header(WT_SESSION_IMPL *session, WT_RECONCILE *r, WT_REC_CHUNK *chunk,
WT_MULTI *multi, WT_PAGE_HEADER *dsk)
{
WT_BTREE *btree;
WT_PAGE *page;
btree = S2BT(session);
page = r->page;
dsk->recno = btree->type == BTREE_ROW ? WT_RECNO_OOB : multi->key.recno;
dsk->write_gen = 0;
dsk->mem_size = multi->size;
dsk->u.entries = chunk->entries;
dsk->type = page->type;
dsk->flags = 0;
/* Set the zero-length value flag in the page header. */
if (page->type == WT_PAGE_ROW_LEAF) {
F_CLR(dsk, WT_PAGE_EMPTY_V_ALL | WT_PAGE_EMPTY_V_NONE);
if (chunk->entries != 0 && r->all_empty_value)
F_SET(dsk, WT_PAGE_EMPTY_V_ALL);
if (chunk->entries != 0 && !r->any_empty_value)
F_SET(dsk, WT_PAGE_EMPTY_V_NONE);
}
/*
* Note in the page header if using the lookaside table eviction path and we found updates that
* weren't globally visible when reconciling this page.
*/
if (F_ISSET(r, WT_REC_LOOKASIDE) && multi->supd != NULL)
F_SET(dsk, WT_PAGE_LAS_UPDATE);
dsk->unused = 0;
dsk->version = __wt_process.page_version_ts ? WT_PAGE_VERSION_TS : WT_PAGE_VERSION_ORIG;
/* Clear the memory owned by the block manager. */
memset(WT_BLOCK_HEADER_REF(dsk), 0, btree->block_header);
}
/*
* __rec_split_write_reuse --
* Check if a previously written block can be reused.
*/
static bool
__rec_split_write_reuse(
WT_SESSION_IMPL *session, WT_RECONCILE *r, WT_MULTI *multi, WT_ITEM *image, bool last_block)
{
WT_MULTI *multi_match;
WT_PAGE_MODIFY *mod;
mod = r->page->modify;
/*
* Don't bother calculating checksums for bulk loads, there's no reason to believe they'll be
* useful. Check because LSM does bulk-loads as part of normal operations and the check is
* cheap.
*/
if (r->is_bulk_load)
return (false);
/*
* Calculating the checksum is the expensive part, try to avoid it.
*
* Ignore the last block of any reconciliation. Pages are written in the same block order every
* time, so the last block written for a page is unlikely to match any previously written block
* or block written in the future, (absent a point-update earlier in the page which didn't
* change the size of the on-page object in any way).
*/
if (last_block)
return (false);
/*
* Quit if evicting with no previously written block to compare against.
* (In other words, if there's eviction pressure and the page was never
* written by a checkpoint, calculating a checksum is worthless.)
*
* Quit if evicting and a previous check failed, once there's a miss no
* future block will match.
*/
if (F_ISSET(r, WT_REC_EVICT)) {
if (mod->rec_result != WT_PM_REC_MULTIBLOCK || mod->mod_multi_entries < r->multi_next)
return (false);
if (r->evict_matching_checksum_failed)
return (false);
}
/* Calculate the checksum for this block. */
multi->checksum = __wt_checksum(image->data, image->size);
/*
* Don't check for a block match when writing blocks during compaction, the whole idea is to
* move those blocks. Check after calculating the checksum, we don't distinguish between pages
* written solely as part of the compaction and pages written at around the same time, and so
* there's a possibility the calculated checksum will be useful in the future.
*/
if (session->compact_state != WT_COMPACT_NONE)
return (false);
/*
* Pages are written in the same block order every time, only check the appropriate slot.
*/
if (mod->rec_result != WT_PM_REC_MULTIBLOCK || mod->mod_multi_entries < r->multi_next)
return (false);
multi_match = &mod->mod_multi[r->multi_next - 1];
if (multi_match->size != multi->size || multi_match->checksum != multi->checksum) {
r->evict_matching_checksum_failed = true;
return (false);
}
multi_match->addr.reuse = 1;
multi->addr = multi_match->addr;
WT_STAT_DATA_INCR(session, rec_page_match);
return (true);
}
/*
* __rec_compression_adjust --
* Adjust the pre-compression page size based on compression results.
*/
static inline void
__rec_compression_adjust(WT_SESSION_IMPL *session, uint32_t max, size_t compressed_size,
bool last_block, uint64_t *adjustp)
{
WT_BTREE *btree;
uint64_t adjust, current, new;
u_int ten_percent;
btree = S2BT(session);
ten_percent = max / 10;
/*
* Changing the pre-compression size updates a shared memory location
* and it's not uncommon to be pushing out large numbers of pages from
* the same file. If compression creates a page larger than the target
* size, decrease the pre-compression size. If compression creates a
* page smaller than the target size, increase the pre-compression size.
* Once we get under the target size, try and stay there to minimize
* shared memory updates, but don't go over the target size, that means
* we're writing bad page sizes.
* Writing a shared memory location without a lock and letting it
* race, minor trickiness so we only read and write the value once.
*/
WT_ORDERED_READ(current, *adjustp);
WT_ASSERT(session, current >= max);
if (compressed_size > max) {
/*
* The compressed size is GT the page maximum. Check if the pre-compression size is larger
* than the maximum. If 10% of the page size larger than the maximum, decrease it by that
* amount. Else if it's not already at the page maximum, set it there.
*
* Note we're using 10% of the maximum page size as our test for when to adjust the
* pre-compression size as well as the amount by which we adjust it. Not updating the value
* when it's close to the page size keeps us from constantly updating a shared memory
* location, and 10% of the page size is an OK step value as well, so we use it in both
* cases.
*/
adjust = current - max;
if (adjust > ten_percent)
new = current - ten_percent;
else if (adjust != 0)
new = max;
else
return;
} else {
/*
* The compressed size is LTE the page maximum.
*
* Don't increase the pre-compressed size on the last block, the last block might be tiny.
*
* If the compressed size is less than the page maximum by 10%, increase the pre-compression
* size by 10% of the page, or up to the maximum in-memory image size.
*
* Note we're using 10% of the maximum page size... see above.
*/
if (last_block || compressed_size > max - ten_percent)
return;
adjust = current + ten_percent;
if (adjust < btree->maxmempage_image)
new = adjust;
else if (current != btree->maxmempage_image)
new = btree->maxmempage_image;
else
return;
}
*adjustp = new;
}
/*
* __rec_split_write --
* Write a disk block out for the split helper functions.
*/
static int
__rec_split_write(WT_SESSION_IMPL *session, WT_RECONCILE *r, WT_REC_CHUNK *chunk,
WT_ITEM *compressed_image, bool last_block)
{
WT_BTREE *btree;
WT_MULTI *multi;
WT_PAGE *page;
size_t addr_size, compressed_size;
uint8_t addr[WT_BTREE_MAX_ADDR_COOKIE];
#ifdef HAVE_DIAGNOSTIC
bool verify_image;
#endif
btree = S2BT(session);
page = r->page;
#ifdef HAVE_DIAGNOSTIC
verify_image = true;
#endif
/* Make sure there's enough room for another write. */
WT_RET(__wt_realloc_def(session, &r->multi_allocated, r->multi_next + 1, &r->multi));
multi = &r->multi[r->multi_next++];
/* Initialize the address (set the addr type for the parent). */
multi->addr.newest_durable_ts = chunk->newest_durable_ts;
multi->addr.oldest_start_ts = chunk->oldest_start_ts;
multi->addr.oldest_start_txn = chunk->oldest_start_txn;
multi->addr.newest_stop_ts = chunk->newest_stop_ts;
multi->addr.newest_stop_txn = chunk->newest_stop_txn;
switch (page->type) {
case WT_PAGE_COL_FIX:
multi->addr.type = WT_ADDR_LEAF_NO;
break;
case WT_PAGE_COL_VAR:
case WT_PAGE_ROW_LEAF:
multi->addr.type = r->ovfl_items ? WT_ADDR_LEAF : WT_ADDR_LEAF_NO;
break;
case WT_PAGE_COL_INT:
case WT_PAGE_ROW_INT:
multi->addr.type = WT_ADDR_INT;
break;
default:
return (__wt_illegal_value(session, page->type));
}
multi->size = WT_STORE_SIZE(chunk->image.size);
multi->checksum = 0;
/* Set the key. */
if (btree->type == BTREE_ROW)
WT_RET(__wt_row_ikey_alloc(session, 0, chunk->key.data, chunk->key.size, &multi->key.ikey));
else
multi->key.recno = chunk->recno;
/* Check if there are saved updates that might belong to this block. */
if (r->supd_next != 0)
WT_RET(__rec_split_write_supd(session, r, chunk, multi, last_block));
/* Initialize the page header(s). */
__rec_split_write_header(session, r, chunk, multi, chunk->image.mem);
if (compressed_image != NULL)
__rec_split_write_header(session, r, chunk, multi, compressed_image->mem);
/*
* If we are writing the whole page in our first/only attempt, it might be a checkpoint
* (checkpoints are only a single page, by definition). Checkpoints aren't written here, the
* wrapup functions do the write.
*
* Track the buffer with the image. (This is bad layering, but we can't write the image until
* the wrapup code, and we don't have a code path from here to there.)
*/
if (last_block && r->multi_next == 1 && __rec_is_checkpoint(session, r)) {
WT_ASSERT(session, r->supd_next == 0);
if (compressed_image == NULL)
r->wrapup_checkpoint = &chunk->image;
else {
r->wrapup_checkpoint = compressed_image;
r->wrapup_checkpoint_compressed = true;
}
return (0);
}
/*
* If configured for an in-memory database, we can't actually write it. Instead, we will
* re-instantiate the page using the disk image and any list of updates we skipped.
*/
if (F_ISSET(r, WT_REC_IN_MEMORY))
goto copy_image;
/*
* If there are saved updates, either doing update/restore eviction or lookaside eviction.
*/
if (multi->supd != NULL) {
/*
* XXX If no entries were used, the page is empty and we can only restore eviction/restore
* or lookaside updates against empty row-store leaf pages, column-store modify attempts to
* allocate a zero-length array.
*/
if (r->page->type != WT_PAGE_ROW_LEAF && chunk->entries == 0)
return (__wt_set_return(session, EBUSY));
if (F_ISSET(r, WT_REC_LOOKASIDE)) {
r->cache_write_lookaside = true;
/*
* Lookaside eviction writes disk images, but if no entries were used, there's no disk
* image to write. There's no more work to do in this case, lookaside eviction doesn't
* copy disk images.
*/
if (chunk->entries == 0)
return (0);
} else {
r->cache_write_restore = true;
/*
* Update/restore never writes a disk image, but always copies a disk image.
*/
goto copy_image;
}
}
/*
* If we wrote this block before, re-use it. Prefer a checksum of the compressed image. It's an
* identical test and should be faster.
*/
if (__rec_split_write_reuse(session, r, multi,
compressed_image == NULL ? &chunk->image : compressed_image, last_block))
goto copy_image;
/* Write the disk image and get an address. */
WT_RET(__wt_bt_write(session, compressed_image == NULL ? &chunk->image : compressed_image, addr,
&addr_size, &compressed_size, false, F_ISSET(r, WT_REC_CHECKPOINT),
compressed_image != NULL));
#ifdef HAVE_DIAGNOSTIC
verify_image = false;
#endif
WT_RET(__wt_memdup(session, addr, addr_size, &multi->addr.addr));
multi->addr.size = (uint8_t)addr_size;
/* Adjust the pre-compression page size based on compression results. */
if (WT_PAGE_IS_INTERNAL(page) && compressed_size != 0 && btree->intlpage_compadjust)
__rec_compression_adjust(
session, btree->maxintlpage, compressed_size, last_block, &btree->maxintlpage_precomp);
if (!WT_PAGE_IS_INTERNAL(page) && compressed_size != 0 && btree->leafpage_compadjust)
__rec_compression_adjust(
session, btree->maxleafpage, compressed_size, last_block, &btree->maxleafpage_precomp);
copy_image:
#ifdef HAVE_DIAGNOSTIC
/*
* The I/O routines verify all disk images we write, but there are paths in reconciliation that
* don't do I/O. Verify those images, too.
*/
WT_ASSERT(session, verify_image == false ||
__wt_verify_dsk_image(
session, "[reconcile-image]", chunk->image.data, 0, &multi->addr, true) == 0);
#endif
/*
* If re-instantiating this page in memory (either because eviction wants to, or because we
* skipped updates to build the disk image), save a copy of the disk image.
*/
if (F_ISSET(r, WT_REC_SCRUB) || (F_ISSET(r, WT_REC_UPDATE_RESTORE) && multi->supd != NULL))
WT_RET(__wt_memdup(session, chunk->image.data, chunk->image.size, &multi->disk_image));
return (0);
}
/*
* __wt_bulk_init --
* Bulk insert initialization.
*/
int
__wt_bulk_init(WT_SESSION_IMPL *session, WT_CURSOR_BULK *cbulk)
{
WT_BTREE *btree;
WT_PAGE_INDEX *pindex;
WT_RECONCILE *r;
uint64_t recno;
btree = S2BT(session);
/*
* Bulk-load is only permitted on newly created files, not any empty file -- see the checkpoint
* code for a discussion.
*/
if (!btree->original)
WT_RET_MSG(session, EINVAL, "bulk-load is only possible for newly created trees");
/*
* Get a reference to the empty leaf page; we have exclusive access so we can take a copy of the
* page, confident the parent won't split.
*/
pindex = WT_INTL_INDEX_GET_SAFE(btree->root.page);
cbulk->ref = pindex->index[0];
cbulk->leaf = cbulk->ref->page;
WT_RET(__rec_init(session, cbulk->ref, 0, NULL, &cbulk->reconcile));
r = cbulk->reconcile;
r->is_bulk_load = true;
recno = btree->type == BTREE_ROW ? WT_RECNO_OOB : 1;
return (__wt_rec_split_init(session, r, cbulk->leaf, recno, btree->maxleafpage_precomp));
}
/*
* __wt_bulk_wrapup --
* Bulk insert cleanup.
*/
int
__wt_bulk_wrapup(WT_SESSION_IMPL *session, WT_CURSOR_BULK *cbulk)
{
WT_BTREE *btree;
WT_DECL_RET;
WT_PAGE *parent;
WT_RECONCILE *r;
btree = S2BT(session);
if ((r = cbulk->reconcile) == NULL)
return (0);
switch (btree->type) {
case BTREE_COL_FIX:
if (cbulk->entry != 0)
__wt_rec_incr(
session, r, cbulk->entry, __bitstr_size((size_t)cbulk->entry * btree->bitcnt));
break;
case BTREE_COL_VAR:
if (cbulk->rle != 0)
WT_ERR(__wt_bulk_insert_var(session, cbulk, false));
break;
case BTREE_ROW:
break;
}
WT_ERR(__wt_rec_split_finish(session, r));
WT_ERR(__rec_write_wrapup(session, r, r->page));
__rec_write_page_status(session, r);
/* Mark the page's parent and the tree dirty. */
parent = r->ref->home;
WT_ERR(__wt_page_modify_init(session, parent));
__wt_page_modify_set(session, parent);
err:
__rec_cleanup(session, r);
__rec_destroy(session, &cbulk->reconcile);
return (ret);
}
/*
* __rec_split_discard --
* Discard the pages resulting from a previous split.
*/
static int
__rec_split_discard(WT_SESSION_IMPL *session, WT_PAGE *page)
{
WT_BTREE *btree;
WT_MULTI *multi;
WT_PAGE_MODIFY *mod;
uint32_t i;
btree = S2BT(session);
mod = page->modify;
/*
* A page that split is being reconciled for the second, or subsequent time; discard underlying
* block space used in the last reconciliation that is not being reused for this reconciliation.
*/
for (multi = mod->mod_multi, i = 0; i < mod->mod_multi_entries; ++multi, ++i) {
if (btree->type == BTREE_ROW)
__wt_free(session, multi->key);
__wt_free(session, multi->disk_image);
__wt_free(session, multi->supd);
/*
* If the page was re-written free the backing disk blocks used in the previous write
* (unless the blocks were reused in this write). The page may instead have been a disk
* image with associated saved updates: ownership of the disk image is transferred when
* rewriting the page in-memory and there may not have been saved updates. We've gotten this
* wrong a few times, so use the existence of an address to confirm backing blocks we care
* about, and free any disk image/saved updates.
*/
if (multi->addr.addr != NULL && !multi->addr.reuse) {
WT_RET(__wt_btree_block_free(session, multi->addr.addr, multi->addr.size));
__wt_free(session, multi->addr.addr);
}
}
__wt_free(session, mod->mod_multi);
mod->mod_multi_entries = 0;
/*
* This routine would be trivial, and only walk a single page freeing any blocks written to
* support the split, except for root splits. In the case of root splits, we have to cope with
* multiple pages in a linked list, and we also have to discard overflow items written for the
* page.
*/
if (WT_PAGE_IS_INTERNAL(page) && mod->mod_root_split != NULL) {
WT_RET(__rec_split_discard(session, mod->mod_root_split));
WT_RET(__wt_ovfl_track_wrapup(session, mod->mod_root_split));
__wt_page_out(session, &mod->mod_root_split);
}
return (0);
}
/*
* __rec_split_dump_keys --
* Dump out the split keys in verbose mode.
*/
static int
__rec_split_dump_keys(WT_SESSION_IMPL *session, WT_RECONCILE *r)
{
WT_BTREE *btree;
WT_DECL_ITEM(tkey);
WT_MULTI *multi;
uint32_t i;
btree = S2BT(session);
__wt_verbose(session, WT_VERB_SPLIT, "split: %" PRIu32 " pages", r->multi_next);
if (btree->type == BTREE_ROW) {
WT_RET(__wt_scr_alloc(session, 0, &tkey));
for (multi = r->multi, i = 0; i < r->multi_next; ++multi, ++i)
__wt_verbose(session, WT_VERB_SPLIT, "starting key %s",
__wt_buf_set_printable(
session, WT_IKEY_DATA(multi->key.ikey), multi->key.ikey->size, tkey));
__wt_scr_free(session, &tkey);
} else
for (multi = r->multi, i = 0; i < r->multi_next; ++multi, ++i)
__wt_verbose(session, WT_VERB_SPLIT, "starting recno %" PRIu64, multi->key.recno);
return (0);
}
/*
* __rec_write_wrapup --
* Finish the reconciliation.
*/
static int
__rec_write_wrapup(WT_SESSION_IMPL *session, WT_RECONCILE *r, WT_PAGE *page)
{
WT_BM *bm;
WT_BTREE *btree;
WT_MULTI *multi;
WT_PAGE_MODIFY *mod;
WT_REF *ref;
uint32_t i;
btree = S2BT(session);
bm = btree->bm;
mod = page->modify;
ref = r->ref;
/*
* This page may have previously been reconciled, and that information is now about to be
* replaced. Make sure it's discarded at some point, and clear the underlying modification
* information, we're creating a new reality.
*/
switch (mod->rec_result) {
case 0: /*
* The page has never been reconciled before, free the original
* address blocks (if any). The "if any" is for empty trees
* created when a new tree is opened or previously deleted pages
* instantiated in memory.
*
* The exception is root pages are never tracked or free'd, they
* are checkpoints, and must be explicitly dropped.
*/
if (__wt_ref_is_root(ref))
break;
WT_RET(__wt_ref_block_free(session, ref));
break;
case WT_PM_REC_EMPTY: /* Page deleted */
break;
case WT_PM_REC_MULTIBLOCK: /* Multiple blocks */
/*
* Discard the multiple replacement blocks.
*/
WT_RET(__rec_split_discard(session, page));
break;
case WT_PM_REC_REPLACE: /* 1-for-1 page swap */
/*
* Discard the replacement leaf page's blocks.
*
* The exception is root pages are never tracked or free'd, they are
* checkpoints, and must be explicitly dropped.
*/
if (!__wt_ref_is_root(ref))
WT_RET(__wt_btree_block_free(session, mod->mod_replace.addr, mod->mod_replace.size));
/* Discard the replacement page's address and disk image. */
__wt_free(session, mod->mod_replace.addr);
mod->mod_replace.size = 0;
__wt_free(session, mod->mod_disk_image);
break;
default:
return (__wt_illegal_value(session, mod->rec_result));
}
/* Reset the reconciliation state. */
mod->rec_result = 0;
/*
* If using the lookaside table eviction path and we found updates that weren't globally visible
* when reconciling this page, copy them into the database's lookaside store.
*/
if (F_ISSET(r, WT_REC_LOOKASIDE))
WT_RET(__rec_las_wrapup(session, r));
/*
* Wrap up overflow tracking. If we are about to create a checkpoint, the system must be
* entirely consistent at that point (the underlying block manager is presumably going to do
* some action to resolve the list of allocated/free/whatever blocks that are associated with
* the checkpoint).
*/
WT_RET(__wt_ovfl_track_wrapup(session, page));
__wt_verbose(session, WT_VERB_RECONCILE, "%p reconciled into %" PRIu32 " pages", (void *)ref,
r->multi_next);
switch (r->multi_next) {
case 0: /* Page delete */
WT_STAT_CONN_INCR(session, rec_page_delete);
WT_STAT_DATA_INCR(session, rec_page_delete);
/*
* If this is the root page, we need to create a sync point. For a page to be empty, it has
* to contain nothing at all, which means it has no records of any kind and is durable.
*/
ref = r->ref;
if (__wt_ref_is_root(ref)) {
__wt_checkpoint_tree_reconcile_update(
session, WT_TS_NONE, WT_TS_NONE, WT_TXN_NONE, WT_TS_MAX, WT_TXN_MAX);
WT_RET(bm->checkpoint(bm, session, NULL, btree->ckpt, false));
}
/*
* If the page was empty, we want to discard it from the tree by discarding the parent's key
* when evicting the parent. Mark the page as deleted, then return success, leaving the page
* in memory. If the page is subsequently modified, that is OK, we'll just reconcile it
* again.
*/
mod->rec_result = WT_PM_REC_EMPTY;
break;
case 1: /* 1-for-1 page swap */
/*
* Because WiredTiger's pages grow without splitting, we're replacing a single page with
* another single page most of the time.
*
* If in-memory, or saving/restoring changes for this page and there's only one block,
* there's nothing to write. Set up a single block as if to split, then use that disk
* image to rewrite the page in memory. This is separate from simple replacements where
* eviction has decided to retain the page in memory because the latter can't handle
* update lists and splits can.
*/
if (F_ISSET(r, WT_REC_IN_MEMORY) ||
(F_ISSET(r, WT_REC_UPDATE_RESTORE) && r->multi->supd_entries != 0))
goto split;
/*
* We may have a root page, create a sync point. (The write code ignores root page updates,
* leaving that work to us.)
*/
if (r->wrapup_checkpoint == NULL) {
mod->mod_replace = r->multi->addr;
r->multi->addr.addr = NULL;
mod->mod_disk_image = r->multi->disk_image;
r->multi->disk_image = NULL;
mod->mod_page_las = r->multi->page_las;
} else {
__wt_checkpoint_tree_reconcile_update(session, r->multi->addr.newest_durable_ts,
r->multi->addr.oldest_start_ts, r->multi->addr.oldest_start_txn,
r->multi->addr.newest_stop_ts, r->multi->addr.newest_stop_txn);
WT_RET(__wt_bt_write(session, r->wrapup_checkpoint, NULL, NULL, NULL, true,
F_ISSET(r, WT_REC_CHECKPOINT), r->wrapup_checkpoint_compressed));
}
mod->rec_result = WT_PM_REC_REPLACE;
break;
default: /* Page split */
if (WT_PAGE_IS_INTERNAL(page))
WT_STAT_DATA_INCR(session, rec_multiblock_internal);
else
WT_STAT_DATA_INCR(session, rec_multiblock_leaf);
/* Optionally display the actual split keys in verbose mode. */
if (WT_VERBOSE_ISSET(session, WT_VERB_SPLIT))
WT_RET(__rec_split_dump_keys(session, r));
/*
* The reuse flag was set in some cases, but we have to clear it, otherwise on subsequent
* reconciliation we would fail to remove blocks that are being discarded.
*/
split:
for (multi = r->multi, i = 0; i < r->multi_next; ++multi, ++i)
multi->addr.reuse = 0;
mod->mod_multi = r->multi;
mod->mod_multi_entries = r->multi_next;
mod->rec_result = WT_PM_REC_MULTIBLOCK;
r->multi = NULL;
r->multi_next = 0;
break;
}
return (0);
}
/*
* __rec_write_wrapup_err --
* Finish the reconciliation on error.
*/
static int
__rec_write_wrapup_err(WT_SESSION_IMPL *session, WT_RECONCILE *r, WT_PAGE *page)
{
WT_DECL_RET;
WT_MULTI *multi;
WT_PAGE_MODIFY *mod;
uint32_t i;
mod = page->modify;
/*
* Clear the address-reused flag from the multiblock reconciliation information (otherwise we
* might think the backing block is being reused on a subsequent reconciliation where we want to
* free it).
*/
if (mod->rec_result == WT_PM_REC_MULTIBLOCK)
for (multi = mod->mod_multi, i = 0; i < mod->mod_multi_entries; ++multi, ++i)
multi->addr.reuse = 0;
/*
* On error, discard blocks we've written, they're unreferenced by the tree. This is not a
* question of correctness, we're avoiding block leaks.
*
* Don't discard backing blocks marked for reuse, they remain part of a previous reconciliation.
*/
for (multi = r->multi, i = 0; i < r->multi_next; ++multi, ++i)
if (multi->addr.addr != NULL) {
if (multi->addr.reuse)
multi->addr.addr = NULL;
else
WT_TRET(__wt_btree_block_free(session, multi->addr.addr, multi->addr.size));
}
/*
* If using the lookaside table eviction path and we found updates that weren't globally visible
* when reconciling this page, we might have already copied them into the database's lookaside
* store. Remove them.
*/
if (F_ISSET(r, WT_REC_LOOKASIDE))
WT_TRET(__rec_las_wrapup_err(session, r));
WT_TRET(__wt_ovfl_track_wrapup_err(session, page));
return (ret);
}
/*
* __rec_las_wrapup --
* Copy all of the saved updates into the database's lookaside table.
*/
static int
__rec_las_wrapup(WT_SESSION_IMPL *session, WT_RECONCILE *r)
{
WT_CURSOR *cursor;
WT_DECL_ITEM(key);
WT_DECL_RET;
WT_MULTI *multi;
uint32_t i, session_flags;
/* Check if there's work to do. */
for (multi = r->multi, i = 0; i < r->multi_next; ++multi, ++i)
if (multi->supd != NULL)
break;
if (i == r->multi_next)
return (0);
/* Ensure enough room for a column-store key without checking. */
WT_RET(__wt_scr_alloc(session, WT_INTPACK64_MAXSIZE, &key));
__wt_las_cursor(session, &cursor, &session_flags);
for (multi = r->multi, i = 0; i < r->multi_next; ++multi, ++i)
if (multi->supd != NULL) {
WT_ERR(__wt_las_insert_block(cursor, S2BT(session), r->page, multi, key));
__wt_free(session, multi->supd);
multi->supd_entries = 0;
}
err:
WT_TRET(__wt_las_cursor_close(session, &cursor, session_flags));
__wt_scr_free(session, &key);
return (ret);
}
/*
* __rec_las_wrapup_err --
* Discard any saved updates from the database's lookaside buffer.
*/
static int
__rec_las_wrapup_err(WT_SESSION_IMPL *session, WT_RECONCILE *r)
{
WT_DECL_RET;
WT_MULTI *multi;
uint64_t las_pageid;
uint32_t i;
/*
* Note the additional check for a non-zero lookaside page ID, that flags if lookaside table
* entries for this page have been written.
*/
for (multi = r->multi, i = 0; i < r->multi_next; ++multi, ++i)
if (multi->supd != NULL && (las_pageid = multi->page_las.las_pageid) != 0)
WT_TRET(__wt_las_remove_block(session, las_pageid));
return (ret);
}
/*
* __wt_rec_cell_build_ovfl --
* Store overflow items in the file, returning the address cookie.
*/
int
__wt_rec_cell_build_ovfl(WT_SESSION_IMPL *session, WT_RECONCILE *r, WT_REC_KV *kv, uint8_t type,
wt_timestamp_t start_ts, uint64_t start_txn, wt_timestamp_t stop_ts, uint64_t stop_txn,
uint64_t rle)
{
WT_BM *bm;
WT_BTREE *btree;
WT_DECL_ITEM(tmp);
WT_DECL_RET;
WT_PAGE *page;
WT_PAGE_HEADER *dsk;
size_t size;
uint8_t *addr, buf[WT_BTREE_MAX_ADDR_COOKIE];
btree = S2BT(session);
bm = btree->bm;
page = r->page;
/* Track if page has overflow items. */
r->ovfl_items = true;
/*
* See if this overflow record has already been written and reuse it if possible, otherwise
* write a new overflow record.
*/
WT_RET(__wt_ovfl_reuse_search(session, page, &addr, &size, kv->buf.data, kv->buf.size));
if (addr == NULL) {
/* Allocate a buffer big enough to write the overflow record. */
size = kv->buf.size;
WT_RET(bm->write_size(bm, session, &size));
WT_RET(__wt_scr_alloc(session, size, &tmp));
/* Initialize the buffer: disk header and overflow record. */
dsk = tmp->mem;
memset(dsk, 0, WT_PAGE_HEADER_SIZE);
dsk->type = WT_PAGE_OVFL;
dsk->u.datalen = (uint32_t)kv->buf.size;
memcpy(WT_PAGE_HEADER_BYTE(btree, dsk), kv->buf.data, kv->buf.size);
dsk->mem_size = WT_PAGE_HEADER_BYTE_SIZE(btree) + (uint32_t)kv->buf.size;
tmp->size = dsk->mem_size;
/* Write the buffer. */
addr = buf;
WT_ERR(__wt_bt_write(
session, tmp, addr, &size, NULL, false, F_ISSET(r, WT_REC_CHECKPOINT), false));
/*
* Track the overflow record (unless it's a bulk load, which by definition won't ever reuse
* a record.
*/
if (!r->is_bulk_load)
WT_ERR(__wt_ovfl_reuse_add(session, page, addr, size, kv->buf.data, kv->buf.size));
}
/* Set the callers K/V to reference the overflow record's address. */
WT_ERR(__wt_buf_set(session, &kv->buf, addr, size));
/* Build the cell and return. */
kv->cell_len = __wt_cell_pack_ovfl(
session, &kv->cell, type, start_ts, start_txn, stop_ts, stop_txn, rle, kv->buf.size);
kv->len = kv->cell_len + kv->buf.size;
err:
__wt_scr_free(session, &tmp);
return (ret);
}
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