/
txn.c
1650 lines (1456 loc) · 46.8 KB
/
txn.c
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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"
/*
* __snapsort_partition --
* Custom quick sort partitioning for snapshots.
*/
static uint32_t
__snapsort_partition(uint64_t *array, uint32_t f, uint32_t l, uint64_t pivot)
{
uint32_t i, j;
i = f - 1;
j = l + 1;
for (;;) {
while (pivot < array[--j])
;
while (array[++i] < pivot)
;
if (i < j) {
uint64_t tmp = array[i];
array[i] = array[j];
array[j] = tmp;
} else
return (j);
}
}
/*
* __snapsort_impl --
* Custom quick sort implementation for snapshots.
*/
static void
__snapsort_impl(uint64_t *array, uint32_t f, uint32_t l)
{
while (f + 16 < l) {
uint64_t v1 = array[f], v2 = array[l], v3 = array[(f + l)/2];
uint64_t median = v1 < v2 ?
(v3 < v1 ? v1 : WT_MIN(v2, v3)) :
(v3 < v2 ? v2 : WT_MIN(v1, v3));
uint32_t m = __snapsort_partition(array, f, l, median);
__snapsort_impl(array, f, m);
f = m + 1;
}
}
/*
* __snapsort --
* Sort an array of transaction IDs.
*/
static void
__snapsort(uint64_t *array, uint32_t size)
{
__snapsort_impl(array, 0, size - 1);
WT_INSERTION_SORT(array, size, uint64_t, WT_TXNID_LT);
}
/*
* __txn_remove_from_global_table --
* Remove the transaction id from the global transaction table.
*/
static inline void
__txn_remove_from_global_table(WT_SESSION_IMPL *session)
{
#ifdef HAVE_DIAGNOSTIC
WT_TXN *txn;
WT_TXN_GLOBAL *txn_global;
WT_TXN_STATE *txn_state;
txn = &session->txn;
txn_global = &S2C(session)->txn_global;
txn_state = WT_SESSION_TXN_STATE(session);
WT_ASSERT(session, !WT_TXNID_LT(txn->id, txn_global->last_running));
WT_ASSERT(session,
txn->id != WT_TXN_NONE && txn_state->id != WT_TXN_NONE);
#else
WT_TXN_STATE *txn_state;
txn_state = WT_SESSION_TXN_STATE(session);
#endif
WT_PUBLISH(txn_state->id, WT_TXN_NONE);
}
/*
* __txn_sort_snapshot --
* Sort a snapshot for faster searching and set the min/max bounds.
*/
static void
__txn_sort_snapshot(WT_SESSION_IMPL *session, uint32_t n, uint64_t snap_max)
{
WT_TXN *txn;
txn = &session->txn;
if (n > 1)
__snapsort(txn->snapshot, n);
txn->snapshot_count = n;
txn->snap_max = snap_max;
txn->snap_min = (n > 0 && WT_TXNID_LE(txn->snapshot[0], snap_max)) ?
txn->snapshot[0] : snap_max;
F_SET(txn, WT_TXN_HAS_SNAPSHOT);
WT_ASSERT(session, n == 0 || txn->snap_min != WT_TXN_NONE);
}
/*
* __wt_txn_release_snapshot --
* Release the snapshot in the current transaction.
*/
void
__wt_txn_release_snapshot(WT_SESSION_IMPL *session)
{
WT_TXN *txn;
WT_TXN_GLOBAL *txn_global;
WT_TXN_STATE *txn_state;
txn = &session->txn;
txn_global = &S2C(session)->txn_global;
txn_state = WT_SESSION_TXN_STATE(session);
WT_ASSERT(session,
txn_state->pinned_id == WT_TXN_NONE ||
session->txn.isolation == WT_ISO_READ_UNCOMMITTED ||
!__wt_txn_visible_all(session, txn_state->pinned_id, WT_TS_NONE));
txn_state->metadata_pinned = txn_state->pinned_id = WT_TXN_NONE;
F_CLR(txn, WT_TXN_HAS_SNAPSHOT);
/* Clear a checkpoint's pinned ID. */
if (WT_SESSION_IS_CHECKPOINT(session)) {
txn_global->checkpoint_state.pinned_id = WT_TXN_NONE;
txn_global->checkpoint_timestamp = 0;
}
__wt_txn_clear_read_timestamp(session);
}
/*
* __wt_txn_get_snapshot --
* Allocate a snapshot.
*/
void
__wt_txn_get_snapshot(WT_SESSION_IMPL *session)
{
WT_CONNECTION_IMPL *conn;
WT_TXN *txn;
WT_TXN_GLOBAL *txn_global;
WT_TXN_STATE *s, *txn_state;
uint64_t commit_gen, current_id, id, prev_oldest_id, pinned_id;
uint32_t i, n, session_cnt;
conn = S2C(session);
txn = &session->txn;
txn_global = &conn->txn_global;
txn_state = WT_SESSION_TXN_STATE(session);
n = 0;
/* Fast path if we already have the current snapshot. */
if ((commit_gen = __wt_session_gen(session, WT_GEN_COMMIT)) != 0) {
if (F_ISSET(txn, WT_TXN_HAS_SNAPSHOT) &&
commit_gen == __wt_gen(session, WT_GEN_COMMIT))
return;
__wt_session_gen_leave(session, WT_GEN_COMMIT);
}
__wt_session_gen_enter(session, WT_GEN_COMMIT);
/* We're going to scan the table: wait for the lock. */
__wt_readlock(session, &txn_global->rwlock);
current_id = pinned_id = txn_global->current;
prev_oldest_id = txn_global->oldest_id;
/*
* Include the checkpoint transaction, if one is running: we should
* ignore any uncommitted changes the checkpoint has written to the
* metadata. We don't have to keep the checkpoint's changes pinned so
* don't including it in the published pinned ID.
*/
if ((id = txn_global->checkpoint_state.id) != WT_TXN_NONE) {
txn->snapshot[n++] = id;
txn_state->metadata_pinned = id;
}
/* For pure read-only workloads, avoid scanning. */
if (prev_oldest_id == current_id) {
txn_state->pinned_id = current_id;
/* Check that the oldest ID has not moved in the meantime. */
WT_ASSERT(session, prev_oldest_id == txn_global->oldest_id);
goto done;
}
/* Walk the array of concurrent transactions. */
WT_ORDERED_READ(session_cnt, conn->session_cnt);
for (i = 0, s = txn_global->states; i < session_cnt; i++, s++) {
/*
* Build our snapshot of any concurrent transaction IDs.
*
* Ignore:
* - Our own ID: we always read our own updates.
* - The ID if it is older than the oldest ID we saw. This
* can happen if we race with a thread that is allocating
* an ID -- the ID will not be used because the thread will
* keep spinning until it gets a valid one.
* - The ID if it is higher than the current ID we saw. This
* can happen if the transaction is already finished. In
* this case, we ignore this transaction because it would
* not be visible to the current snapshot.
*/
while (s != txn_state &&
(id = s->id) != WT_TXN_NONE &&
WT_TXNID_LE(prev_oldest_id, id) &&
WT_TXNID_LT(id, current_id)) {
/*
* If the transaction is still allocating its ID, then
* we spin here until it gets its valid ID.
*/
WT_READ_BARRIER();
if (!s->is_allocating) {
/*
* There is still a chance that fetched ID is
* not valid after ID allocation, so we check
* again here. The read of transaction ID
* should be carefully ordered: we want to
* re-read ID from transaction state after this
* transaction completes ID allocation.
*/
WT_READ_BARRIER();
if (id == s->id) {
txn->snapshot[n++] = id;
if (WT_TXNID_LT(id, pinned_id))
pinned_id = id;
break;
}
}
WT_PAUSE();
}
}
/*
* If we got a new snapshot, update the published pinned ID for this
* session.
*/
WT_ASSERT(session, WT_TXNID_LE(prev_oldest_id, pinned_id));
WT_ASSERT(session, prev_oldest_id == txn_global->oldest_id);
txn_state->pinned_id = pinned_id;
done: __wt_readunlock(session, &txn_global->rwlock);
__txn_sort_snapshot(session, n, current_id);
}
/*
* __txn_oldest_scan --
* Sweep the running transactions to calculate the oldest ID required.
*/
static void
__txn_oldest_scan(WT_SESSION_IMPL *session,
uint64_t *oldest_idp, uint64_t *last_runningp, uint64_t *metadata_pinnedp,
WT_SESSION_IMPL **oldest_sessionp)
{
WT_CONNECTION_IMPL *conn;
WT_SESSION_IMPL *oldest_session;
WT_TXN_GLOBAL *txn_global;
WT_TXN_STATE *s;
uint64_t id, last_running, metadata_pinned, oldest_id, prev_oldest_id;
uint32_t i, session_cnt;
conn = S2C(session);
txn_global = &conn->txn_global;
oldest_session = NULL;
/* The oldest ID cannot change while we are holding the scan lock. */
prev_oldest_id = txn_global->oldest_id;
last_running = oldest_id = txn_global->current;
if ((metadata_pinned = txn_global->checkpoint_state.id) == WT_TXN_NONE)
metadata_pinned = oldest_id;
/* Walk the array of concurrent transactions. */
WT_ORDERED_READ(session_cnt, conn->session_cnt);
for (i = 0, s = txn_global->states; i < session_cnt; i++, s++) {
/* Update the last running transaction ID. */
while ((id = s->id) != WT_TXN_NONE &&
WT_TXNID_LE(prev_oldest_id, id) &&
WT_TXNID_LT(id, last_running)) {
/*
* If the transaction is still allocating its ID, then
* we spin here until it gets its valid ID.
*/
WT_READ_BARRIER();
if (!s->is_allocating) {
/*
* There is still a chance that fetched ID is
* not valid after ID allocation, so we check
* again here. The read of transaction ID
* should be carefully ordered: we want to
* re-read ID from transaction state after this
* transaction completes ID allocation.
*/
WT_READ_BARRIER();
if (id == s->id) {
last_running = id;
break;
}
}
WT_PAUSE();
}
/* Update the metadata pinned ID. */
if ((id = s->metadata_pinned) != WT_TXN_NONE &&
WT_TXNID_LT(id, metadata_pinned))
metadata_pinned = id;
/*
* !!!
* Note: Don't ignore pinned ID values older than the previous
* oldest ID. Read-uncommitted operations publish pinned ID
* values without acquiring the scan lock to protect the global
* table. See the comment in __wt_txn_cursor_op for more
* details.
*/
if ((id = s->pinned_id) != WT_TXN_NONE &&
WT_TXNID_LT(id, oldest_id)) {
oldest_id = id;
oldest_session = &conn->sessions[i];
}
}
if (WT_TXNID_LT(last_running, oldest_id))
oldest_id = last_running;
/* The oldest ID can't move past any named snapshots. */
if ((id = txn_global->nsnap_oldest_id) != WT_TXN_NONE &&
WT_TXNID_LT(id, oldest_id))
oldest_id = id;
/* The metadata pinned ID can't move past the oldest ID. */
if (WT_TXNID_LT(oldest_id, metadata_pinned))
metadata_pinned = oldest_id;
*last_runningp = last_running;
*metadata_pinnedp = metadata_pinned;
*oldest_idp = oldest_id;
*oldest_sessionp = oldest_session;
}
/*
* __wt_txn_update_oldest --
* Sweep the running transactions to update the oldest ID required.
*/
int
__wt_txn_update_oldest(WT_SESSION_IMPL *session, uint32_t flags)
{
WT_CONNECTION_IMPL *conn;
WT_DECL_RET;
WT_SESSION_IMPL *oldest_session;
WT_TXN_GLOBAL *txn_global;
uint64_t current_id, last_running, metadata_pinned, oldest_id;
uint64_t prev_last_running, prev_metadata_pinned, prev_oldest_id;
bool strict, wait;
conn = S2C(session);
txn_global = &conn->txn_global;
strict = LF_ISSET(WT_TXN_OLDEST_STRICT);
wait = LF_ISSET(WT_TXN_OLDEST_WAIT);
current_id = last_running = metadata_pinned = txn_global->current;
prev_last_running = txn_global->last_running;
prev_metadata_pinned = txn_global->metadata_pinned;
prev_oldest_id = txn_global->oldest_id;
/* Try to move the pinned timestamp forward. */
if (strict)
WT_RET(__wt_txn_update_pinned_timestamp(session, false));
/*
* For pure read-only workloads, or if the update isn't forced and the
* oldest ID isn't too far behind, avoid scanning.
*/
if ((prev_oldest_id == current_id &&
prev_metadata_pinned == current_id) ||
(!strict && WT_TXNID_LT(current_id, prev_oldest_id + 100)))
return (0);
/* First do a read-only scan. */
if (wait)
__wt_readlock(session, &txn_global->rwlock);
else if ((ret =
__wt_try_readlock(session, &txn_global->rwlock)) != 0)
return (ret == EBUSY ? 0 : ret);
__txn_oldest_scan(session,
&oldest_id, &last_running, &metadata_pinned, &oldest_session);
__wt_readunlock(session, &txn_global->rwlock);
/*
* If the state hasn't changed (or hasn't moved far enough for
* non-forced updates), give up.
*/
if ((oldest_id == prev_oldest_id ||
(!strict && WT_TXNID_LT(oldest_id, prev_oldest_id + 100))) &&
((last_running == prev_last_running) ||
(!strict && WT_TXNID_LT(last_running, prev_last_running + 100))) &&
metadata_pinned == prev_metadata_pinned)
return (0);
/* It looks like an update is necessary, wait for exclusive access. */
if (wait)
__wt_writelock(session, &txn_global->rwlock);
else if ((ret =
__wt_try_writelock(session, &txn_global->rwlock)) != 0)
return (ret == EBUSY ? 0 : ret);
/*
* If the oldest ID has been updated while we waited, don't bother
* scanning.
*/
if (WT_TXNID_LE(oldest_id, txn_global->oldest_id) &&
WT_TXNID_LE(last_running, txn_global->last_running) &&
WT_TXNID_LE(metadata_pinned, txn_global->metadata_pinned))
goto done;
/*
* Re-scan now that we have exclusive access. This is necessary because
* threads get transaction snapshots with read locks, and we have to be
* sure that there isn't a thread that has got a snapshot locally but
* not yet published its snap_min.
*/
__txn_oldest_scan(session,
&oldest_id, &last_running, &metadata_pinned, &oldest_session);
#ifdef HAVE_DIAGNOSTIC
{
/*
* Make sure the ID doesn't move past any named snapshots.
*
* Don't include the read/assignment in the assert statement. Coverity
* complains if there are assignments only done in diagnostic builds,
* and when the read is from a volatile.
*/
uint64_t id = txn_global->nsnap_oldest_id;
WT_ASSERT(session,
id == WT_TXN_NONE || !WT_TXNID_LT(id, oldest_id));
}
#endif
/* Update the public IDs. */
if (WT_TXNID_LT(txn_global->metadata_pinned, metadata_pinned))
txn_global->metadata_pinned = metadata_pinned;
if (WT_TXNID_LT(txn_global->oldest_id, oldest_id))
txn_global->oldest_id = oldest_id;
if (WT_TXNID_LT(txn_global->last_running, last_running)) {
txn_global->last_running = last_running;
/* Output a verbose message about long-running transactions,
* but only when some progress is being made. */
if (WT_VERBOSE_ISSET(session, WT_VERB_TRANSACTION) &&
current_id - oldest_id > 10000 && oldest_session != NULL) {
__wt_verbose(session, WT_VERB_TRANSACTION,
"old snapshot %" PRIu64
" pinned in session %" PRIu32 " [%s]"
" with snap_min %" PRIu64,
oldest_id, oldest_session->id,
oldest_session->lastop,
oldest_session->txn.snap_min);
}
}
done: __wt_writeunlock(session, &txn_global->rwlock);
return (ret);
}
/*
* __wt_txn_config --
* Configure a transaction.
*/
int
__wt_txn_config(WT_SESSION_IMPL *session, const char *cfg[])
{
WT_CONFIG_ITEM cval;
WT_TXN *txn;
wt_timestamp_t read_ts;
txn = &session->txn;
WT_RET(__wt_config_gets_def(session, cfg, "isolation", 0, &cval));
if (cval.len != 0)
txn->isolation =
WT_STRING_MATCH("snapshot", cval.str, cval.len) ?
WT_ISO_SNAPSHOT :
WT_STRING_MATCH("read-committed", cval.str, cval.len) ?
WT_ISO_READ_COMMITTED : WT_ISO_READ_UNCOMMITTED;
/*
* The default sync setting is inherited from the connection, but can
* be overridden by an explicit "sync" setting for this transaction.
*
* We want to distinguish between inheriting implicitly and explicitly.
*/
F_CLR(txn, WT_TXN_SYNC_SET);
WT_RET(__wt_config_gets_def(
session, cfg, "sync", (int)UINT_MAX, &cval));
if (cval.val == 0 || cval.val == 1)
/*
* This is an explicit setting of sync. Set the flag so
* that we know not to overwrite it in commit_transaction.
*/
F_SET(txn, WT_TXN_SYNC_SET);
/*
* If sync is turned off explicitly, clear the transaction's sync field.
*/
if (cval.val == 0)
txn->txn_logsync = 0;
WT_RET(__wt_config_gets_def(session, cfg, "snapshot", 0, &cval));
if (cval.len > 0)
/*
* The layering here isn't ideal - the named snapshot get
* function does both validation and setup. Otherwise we'd
* need to walk the list of named snapshots twice during
* transaction open.
*/
WT_RET(__wt_txn_named_snapshot_get(session, &cval));
/* Check if prepared updates should be ignored during reads. */
WT_RET(__wt_config_gets_def(session, cfg, "ignore_prepare", 0, &cval));
if (cval.val)
F_SET(txn, WT_TXN_IGNORE_PREPARE);
/*
* Check if the prepare timestamp and the commit timestamp of a
* prepared transaction need to be rounded up.
*/
WT_RET(__wt_config_gets_def(
session, cfg, "roundup_timestamps.prepared", 0, &cval));
if (cval.val)
F_SET(txn, WT_TXN_TS_ROUND_PREPARED);
/* Check if read timestamp needs to be rounded up. */
WT_RET(__wt_config_gets_def(
session, cfg, "roundup_timestamps.read", 0, &cval));
if (cval.val)
F_SET(txn, WT_TXN_TS_ROUND_READ);
WT_RET(__wt_config_gets_def(session, cfg, "read_timestamp", 0, &cval));
if (cval.len != 0) {
WT_RET(__wt_txn_parse_timestamp(
session, "read", &read_ts, &cval));
WT_RET(__wt_txn_set_read_timestamp(session, read_ts));
}
return (0);
}
/*
* __wt_txn_reconfigure --
* WT_SESSION::reconfigure for transactions.
*/
int
__wt_txn_reconfigure(WT_SESSION_IMPL *session, const char *config)
{
WT_CONFIG_ITEM cval;
WT_DECL_RET;
WT_TXN *txn;
txn = &session->txn;
ret = __wt_config_getones(session, config, "isolation", &cval);
if (ret == 0 && cval.len != 0) {
session->isolation = txn->isolation =
WT_STRING_MATCH("snapshot", cval.str, cval.len) ?
WT_ISO_SNAPSHOT :
WT_STRING_MATCH("read-uncommitted", cval.str, cval.len) ?
WT_ISO_READ_UNCOMMITTED : WT_ISO_READ_COMMITTED;
}
WT_RET_NOTFOUND_OK(ret);
return (0);
}
/*
* __wt_txn_release --
* Release the resources associated with the current transaction.
*/
void
__wt_txn_release(WT_SESSION_IMPL *session)
{
WT_TXN *txn;
WT_TXN_GLOBAL *txn_global;
txn = &session->txn;
txn_global = &S2C(session)->txn_global;
WT_ASSERT(session, txn->mod_count == 0);
txn->notify = NULL;
/* Clear the transaction's ID from the global table. */
if (WT_SESSION_IS_CHECKPOINT(session)) {
WT_ASSERT(session,
WT_SESSION_TXN_STATE(session)->id == WT_TXN_NONE);
txn->id = txn_global->checkpoint_state.id = WT_TXN_NONE;
/*
* Be extra careful to cleanup everything for checkpoints: once
* the global checkpoint ID is cleared, we can no longer tell
* if this session is doing a checkpoint.
*/
txn_global->checkpoint_id = 0;
} else if (F_ISSET(txn, WT_TXN_HAS_ID)) {
/*
* If transaction is prepared, this would have been done in
* prepare.
*/
if (!F_ISSET(txn, WT_TXN_PREPARE))
__txn_remove_from_global_table(session);
txn->id = WT_TXN_NONE;
}
__wt_txn_clear_commit_timestamp(session);
/* Free the scratch buffer allocated for logging. */
__wt_logrec_free(session, &txn->logrec);
/* Discard any memory from the session's stash that we can. */
WT_ASSERT(session, __wt_session_gen(session, WT_GEN_SPLIT) == 0);
__wt_stash_discard(session);
/*
* Reset the transaction state to not running and release the snapshot.
*/
__wt_txn_release_snapshot(session);
txn->isolation = session->isolation;
#ifdef HAVE_DIAGNOSTIC
txn->multi_update_count = 0;
#endif
txn->rollback_reason = NULL;
/* Ensure the transaction flags are cleared on exit */
txn->flags = 0;
txn->prepare_timestamp = WT_TS_NONE;
txn->durable_timestamp = WT_TS_NONE;
}
/*
* __txn_commit_timestamps_assert --
* Validate that timestamps provided to commit are legal.
*/
static inline int
__txn_commit_timestamps_assert(WT_SESSION_IMPL *session)
{
WT_CURSOR *cursor;
WT_DECL_RET;
WT_TXN *txn;
WT_TXN_OP *op;
WT_UPDATE *upd;
wt_timestamp_t op_timestamp;
u_int i;
const char *open_cursor_cfg[] = {
WT_CONFIG_BASE(session, WT_SESSION_open_cursor), NULL };
bool op_zero_ts, upd_zero_ts;
txn = &session->txn;
/*
* Debugging checks on timestamps, if user requested them.
*/
if (F_ISSET(txn, WT_TXN_TS_COMMIT_ALWAYS) &&
!F_ISSET(txn, WT_TXN_HAS_TS_COMMIT) &&
txn->mod_count != 0)
WT_RET_MSG(session, EINVAL, "commit_timestamp required and "
"none set on this transaction");
if (F_ISSET(txn, WT_TXN_TS_COMMIT_NEVER) &&
F_ISSET(txn, WT_TXN_HAS_TS_COMMIT) &&
txn->mod_count != 0)
WT_RET_MSG(session, EINVAL, "no commit_timestamp required and "
"timestamp set on this transaction");
if (F_ISSET(txn, WT_TXN_TS_DURABLE_ALWAYS) &&
!F_ISSET(txn, WT_TXN_HAS_TS_DURABLE) &&
txn->mod_count != 0)
WT_RET_MSG(session, EINVAL, "durable_timestamp required and "
"none set on this transaction");
if (F_ISSET(txn, WT_TXN_TS_DURABLE_NEVER) &&
F_ISSET(txn, WT_TXN_HAS_TS_DURABLE) &&
txn->mod_count != 0)
WT_RET_MSG(session, EINVAL, "no durable_timestamp required and "
"durable timestamp set on this transaction");
/*
* If we're not doing any key consistency checking, we're done.
*/
if (!F_ISSET(txn, WT_TXN_TS_COMMIT_KEYS | WT_TXN_TS_DURABLE_KEYS))
return (0);
/*
* Error on any valid update structures for the same key that
* are at a later timestamp or use timestamps inconsistently.
*/
for (i = 0, op = txn->mod; i < txn->mod_count; i++, op++)
if (op->type == WT_TXN_OP_BASIC_COL ||
op->type == WT_TXN_OP_BASIC_ROW) {
/*
* Search for prepared updates, so that they will be
* restored, if moved to lookaside.
*/
if (F_ISSET(txn, WT_TXN_PREPARE)) {
WT_RET(__wt_open_cursor(session,
op->btree->dhandle->name, NULL,
open_cursor_cfg, &cursor));
F_CLR(txn, WT_TXN_PREPARE);
if (op->type == WT_TXN_OP_BASIC_ROW)
__wt_cursor_set_raw_key(
cursor, &op->u.op_row.key);
else
((WT_CURSOR_BTREE*)cursor)->iface.recno
= op->u.op_col.recno;
F_SET(txn, WT_TXN_PREPARE);
WT_WITH_BTREE(session, op->btree,
ret = __wt_btcur_search_uncommitted(
(WT_CURSOR_BTREE *)cursor, &upd));
WT_TRET(cursor->close(cursor));
if (ret != 0)
WT_RET_MSG(session, EINVAL,
"prepared update restore failed");
op->u.op_upd = upd;
} else
upd = op->u.op_upd->next;
/*
* Skip over any aborted update structures or ones
* from our own transaction.
*/
while (upd != NULL && (upd->txnid == WT_TXN_ABORTED ||
upd->txnid == txn->id))
upd = upd->next;
/*
* Check the timestamp on this update with the
* first valid update in the chain. They're in
* most recent order.
*/
if (upd == NULL)
continue;
/*
* Check for consistent per-key timestamp usage.
* If timestamps are or are not used originally then
* they should be used the same way always. For this
* transaction, timestamps are in use anytime the
* commit timestamp is set.
* Check timestamps are used in order.
*/
op_zero_ts = !F_ISSET(txn, WT_TXN_HAS_TS_COMMIT);
upd_zero_ts = upd->start_ts == WT_TS_NONE;
if (op_zero_ts != upd_zero_ts)
WT_RET_MSG(session, EINVAL,
"per-key timestamps used inconsistently");
/*
* If we aren't using timestamps for this transaction
* then we are done checking. Don't check the timestamp
* because the one in the transaction is not cleared.
*/
if (op_zero_ts)
continue;
op_timestamp = op->u.op_upd->start_ts;
/*
* Only if the update structure doesn't have a timestamp
* then use the one in the transaction structure.
*/
if (op_timestamp == WT_TS_NONE)
op_timestamp = txn->commit_timestamp;
if (F_ISSET(txn, WT_TXN_TS_COMMIT_KEYS) &&
op_timestamp < upd->start_ts)
WT_RET_MSG(session, EINVAL,
"out of order commit timestamps");
if (F_ISSET(txn, WT_TXN_TS_DURABLE_KEYS) &&
txn->durable_timestamp < upd->durable_ts)
WT_RET_MSG(session, EINVAL,
"out of order durable timestamps");
}
return (0);
}
/*
* __wt_txn_commit --
* Commit the current transaction.
*/
int
__wt_txn_commit(WT_SESSION_IMPL *session, const char *cfg[])
{
WT_CONFIG_ITEM cval;
WT_CONNECTION_IMPL *conn;
WT_DECL_RET;
WT_TXN *txn;
WT_TXN_GLOBAL *txn_global;
WT_TXN_OP *op;
WT_UPDATE *upd;
wt_timestamp_t prev_commit_timestamp;
uint32_t fileid;
u_int i;
bool locked, prepare, readonly, update_timestamp;
txn = &session->txn;
conn = S2C(session);
txn_global = &conn->txn_global;
prev_commit_timestamp = 0; /* -Wconditional-uninitialized */
locked = false;
WT_ASSERT(session, F_ISSET(txn, WT_TXN_RUNNING));
WT_ASSERT(session, !F_ISSET(txn, WT_TXN_ERROR) ||
txn->mod_count == 0);
readonly = txn->mod_count == 0;
prepare = F_ISSET(txn, WT_TXN_PREPARE);
/*
* Clear the prepared round up flag if the transaction is not prepared.
* There is no rounding up to do in that case.
*/
if (!prepare)
F_CLR(txn, WT_TXN_TS_ROUND_PREPARED);
/* Set the commit and the durable timestamps. */
WT_ERR(__wt_txn_set_timestamp(session, cfg));
if (prepare) {
if (!F_ISSET(txn, WT_TXN_HAS_TS_COMMIT))
WT_ERR_MSG(session, EINVAL,
"commit_timestamp is required for a prepared "
"transaction");
if (!F_ISSET(txn, WT_TXN_HAS_TS_DURABLE))
WT_ERR_MSG(session, EINVAL,
"durable_timestamp is required for a prepared "
"transaction");
WT_ASSERT(session,
txn->prepare_timestamp <= txn->commit_timestamp);
} else {
if (F_ISSET(txn, WT_TXN_HAS_TS_PREPARE))
WT_ERR_MSG(session, EINVAL,
"prepare timestamp is set for non-prepared "
"transaction");
if (F_ISSET(txn, WT_TXN_HAS_TS_DURABLE))
WT_ERR_MSG(session, EINVAL,
"durable_timestamp should not be specified for "
"non-prepared transaction");
}
if (F_ISSET(txn, WT_TXN_HAS_TS_COMMIT))
WT_ASSERT(session,
txn->commit_timestamp <= txn->durable_timestamp);
WT_ERR(__txn_commit_timestamps_assert(session));
/*
* The default sync setting is inherited from the connection, but can
* be overridden by an explicit "sync" setting for this transaction.
*/
WT_ERR(__wt_config_gets_def(session, cfg, "sync", 0, &cval));
/*
* If the user chose the default setting, check whether sync is enabled
* for this transaction (either inherited or via begin_transaction).
* If sync is disabled, clear the field to avoid the log write being
* flushed.
*
* Otherwise check for specific settings. We don't need to check for
* "on" because that is the default inherited from the connection. If
* the user set anything in begin_transaction, we only override with an
* explicit setting.
*/
if (cval.len == 0) {
if (!FLD_ISSET(txn->txn_logsync, WT_LOG_SYNC_ENABLED) &&
!F_ISSET(txn, WT_TXN_SYNC_SET))
txn->txn_logsync = 0;
} else {
/*
* If the caller already set sync on begin_transaction then
* they should not be using sync on commit_transaction.
* Flag that as an error.
*/
if (F_ISSET(txn, WT_TXN_SYNC_SET))
WT_ERR_MSG(session, EINVAL,
"Sync already set during begin_transaction");
if (WT_STRING_MATCH("background", cval.str, cval.len))
txn->txn_logsync = WT_LOG_BACKGROUND;
else if (WT_STRING_MATCH("off", cval.str, cval.len))
txn->txn_logsync = 0;
/*
* We don't need to check for "on" here because that is the
* default to inherit from the connection setting.
*/
}
/* Commit notification. */
if (txn->notify != NULL)
WT_ERR(txn->notify->notify(txn->notify,
(WT_SESSION *)session, txn->id, 1));
/*
* We are about to release the snapshot: copy values into any
* positioned cursors so they don't point to updates that could be
* freed once we don't have a snapshot.
* If this transaction is prepared, then copying values would have been
* done during prepare.
*/
if (session->ncursors > 0 && !prepare) {
WT_DIAGNOSTIC_YIELD;
WT_ERR(__wt_session_copy_values(session));
}
/* If we are logging, write a commit log record. */
if (txn->logrec != NULL &&
FLD_ISSET(conn->log_flags, WT_CONN_LOG_ENABLED) &&
!F_ISSET(session, WT_SESSION_NO_LOGGING)) {
/*
* We are about to block on I/O writing the log.
* Release our snapshot in case it is keeping data pinned.
* This is particularly important for checkpoints.
*/
__wt_txn_release_snapshot(session);
/*
* We hold the visibility lock for reading from the time
* we write our log record until the time we release our
* transaction so that the LSN any checkpoint gets will
* always reflect visible data.
*/
__wt_readlock(session, &txn_global->visibility_rwlock);
locked = true;
WT_ERR(__wt_txn_log_commit(session, cfg));
}
/* Note: we're going to commit: nothing can fail after this point. */
/* Process and free updates. */
for (i = 0, op = txn->mod; i < txn->mod_count; i++, op++) {
fileid = op->btree->id;
switch (op->type) {
case WT_TXN_OP_NONE:
break;
case WT_TXN_OP_BASIC_COL:
case WT_TXN_OP_BASIC_ROW:
case WT_TXN_OP_INMEM_COL:
case WT_TXN_OP_INMEM_ROW:
upd = op->u.op_upd;
/*
* Need to resolve indirect references of transaction
* operation, in case of prepared transaction.
*/
if (!prepare) {
/*
* Switch reserved operations to abort to
* simplify obsolete update list truncation.
*/
if (upd->type == WT_UPDATE_RESERVE) {
upd->txnid = WT_TXN_ABORTED;
break;
}
/*
* Writes to the lookaside file can be evicted
* as soon as they commit.
*/
if (conn->cache->las_fileid != 0 &&
fileid == conn->cache->las_fileid) {
upd->txnid = WT_TXN_NONE;
break;
}
__wt_txn_op_set_timestamp(session, op);
} else {
WT_ERR(__wt_txn_resolve_prepared_op(
session, op, true));
}
break;
case WT_TXN_OP_REF_DELETE:
__wt_txn_op_set_timestamp(session, op);
break;
case WT_TXN_OP_TRUNCATE_COL:
case WT_TXN_OP_TRUNCATE_ROW:
/* Other operations don't need timestamps. */
break;
}
__wt_txn_op_free(session, op);
}
/*
* FIXME: I think we want to say that all prepared updates were
* resolved.
* WT_ASSERT(session, txn->multi_update_count == 0);