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mdbx: rework mdbx_env_sync().

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Change-Id: I6192e8a333b607d1e46eadddb73863943635f1ec
This commit is contained in:
Leo Yuriev 2017-05-18 02:21:39 +03:00
parent 7a4541f598
commit c479c5ff15
1 changed files with 62 additions and 45 deletions
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107
src/mdbx.c
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@ -656,7 +656,8 @@ static int mdbx_page_split(MDB_cursor *mc, MDB_val *newkey, MDB_val *newdata,
pgno_t newpgno, unsigned nflags);
static int mdbx_read_header(MDB_env *env, MDB_meta *meta);
static int mdbx_env_sync0(MDB_env *env, unsigned flags, MDB_meta *pending);
static int mdbx_env_sync_locked(MDB_env *env, unsigned flags,
MDB_meta *pending);
static void mdbx_env_close0(MDB_env *env);
static MDB_node *mdbx_node_search(MDB_cursor *mc, MDB_val *key, int *exactp);
@ -1724,7 +1725,7 @@ static int mdbx_page_alloc(MDB_cursor *mc, int num, MDB_page **mp, int flags) {
me_flags |= MDBX_UTTERLY_NOSYNC;
mdbx_assert(env, env->me_sync_pending > 0);
if (mdbx_env_sync0(env, me_flags, &meta) == MDB_SUCCESS) {
if (mdbx_env_sync_locked(env, me_flags, &meta) == MDB_SUCCESS) {
txnid_t snap = mdbx_find_oldest(env, NULL);
if (snap > oldest) {
continue;
@ -1969,10 +1970,6 @@ fail:
}
int mdbx_env_sync(MDB_env *env, int force) {
int rc;
MDB_meta *head;
unsigned flags;
if (unlikely(!env))
return MDBX_EINVAL;
@ -1982,49 +1979,60 @@ int mdbx_env_sync(MDB_env *env, int force) {
if (unlikely(!env->me_lck))
return MDB_PANIC;
flags = env->me_flags & ~MDB_NOMETASYNC;
unsigned flags = env->me_flags & ~MDB_NOMETASYNC;
if (unlikely(flags & (MDB_RDONLY | MDB_FATAL_ERROR)))
return MDBX_EACCESS;
head = mdbx_meta_head(env);
if (!META_IS_WEAK(head) && env->me_sync_pending == 0 &&
env->me_mapsize == head->mm_mapsize)
/* LY: nothing to do */
return MDB_SUCCESS;
if (force || head->mm_mapsize != env->me_mapsize ||
(env->me_sync_threshold &&
env->me_sync_pending >= env->me_sync_threshold))
flags &= MDB_WRITEMAP;
/* LY: early sync before acquiring the mutex to reduce writer's latency */
if (env->me_sync_pending > env->me_psize * 16 && (flags & MDB_NOSYNC) == 0) {
assert(((flags ^ env->me_flags) & MDB_WRITEMAP) == 0);
if (flags & MDB_WRITEMAP) {
size_t used_size = env->me_psize * (head->mm_last_pg + 1);
rc = mdbx_msync(env->me_map, used_size, flags & MDB_MAPASYNC);
} else {
rc = mdbx_filesync(env->me_fd, false);
}
if (unlikely(rc != MDB_SUCCESS))
return rc;
}
rc = mdbx_txn_lock(env);
int rc = mdbx_txn_lock(env);
if (unlikely(rc != MDB_SUCCESS))
return rc;
/* LY: head may be changed while the mutex has been acquired. */
head = mdbx_meta_head(env);
rc = MDB_SUCCESS;
if (META_IS_WEAK(head) || env->me_sync_pending != 0 ||
MDB_meta *head = mdbx_meta_head(env);
if (!META_IS_STEADY(head) || env->me_sync_pending ||
env->me_mapsize != head->mm_mapsize) {
MDB_meta meta = *head;
rc = mdbx_env_sync0(env, flags, &meta);
if (force || head->mm_mapsize != env->me_mapsize ||
(env->me_sync_threshold &&
env->me_sync_pending >= env->me_sync_threshold))
flags &= MDB_WRITEMAP /* clear flags for full steady sync */;
if (env->me_sync_pending > env->me_psize * 16 &&
(flags & MDB_NOSYNC) == 0) {
assert(((flags ^ env->me_flags) & MDB_WRITEMAP) == 0);
size_t used_size = env->me_psize * (head->mm_last_pg + 1);
mdbx_txn_unlock(env);
/* LY: pre-sync without holding lock to reduce latency for writer(s) */
if (flags & MDB_WRITEMAP) {
rc = mdbx_msync(env->me_map, used_size, flags & MDB_MAPASYNC);
} else {
rc = mdbx_filesync(env->me_fd, false);
}
if (unlikely(rc != MDB_SUCCESS))
return rc;
rc = mdbx_txn_lock(env);
if (unlikely(rc != MDB_SUCCESS))
return rc;
/* LY: head may be changed. */
head = mdbx_meta_head(env);
}
if (!META_IS_STEADY(head) || env->me_sync_pending ||
env->me_mapsize != head->mm_mapsize) {
MDB_meta meta = *head;
rc = mdbx_env_sync_locked(env, flags, &meta);
if (unlikely(rc != MDB_SUCCESS)) {
mdbx_txn_unlock(env);
return rc;
}
}
}
mdbx_txn_unlock(env);
return rc;
assert(rc == MDB_SUCCESS);
return MDB_SUCCESS;
}
/** Back up parent txn's cursors, then grab the originals for tracking */
@ -3266,7 +3274,7 @@ int mdbx_txn_commit(MDB_txn *txn) {
meta.mm_txnid = txn->mt_txnid;
meta.mm_canary = txn->mt_canary;
rc = mdbx_env_sync0(env, env->me_flags | txn->mt_flags, &meta);
rc = mdbx_env_sync_locked(env, env->me_flags | txn->mt_flags, &meta);
}
if (unlikely(rc != MDB_SUCCESS))
goto fail;
@ -3396,7 +3404,8 @@ static int __cold mdbx_env_init_meta(MDB_env *env, MDB_meta *meta) {
return rc;
}
static int mdbx_env_sync0(MDB_env *env, unsigned flags, MDB_meta *pending) {
static int mdbx_env_sync_locked(MDB_env *env, unsigned flags,
MDB_meta *pending) {
int rc;
MDB_meta *head = mdbx_meta_head(env);
size_t prev_mapsize = head->mm_mapsize;
@ -3484,10 +3493,15 @@ static int mdbx_env_sync0(MDB_env *env, unsigned flags, MDB_meta *pending) {
: "Legacy");
if (env->me_flags & MDB_WRITEMAP) {
/* LY: 'invalidate' the meta,
* but mdbx_meta_head_r() will be confused/retired in collision case. */
target->mm_datasync_sign = MDB_DATASIGN_WEAK;
target->mm_txnid = 0;
/* LY: 'invalidate' the meta. */
mdbx_jitter4testing(true);
if (target->mm_datasync_sign != MDB_DATASIGN_WEAK ||
target->mm_txnid != pending->mm_txnid) {
target->mm_datasync_sign = MDB_DATASIGN_WEAK;
mdbx_jitter4testing(true);
target->mm_txnid = 0;
mdbx_jitter4testing(true);
}
/* LY: update info */
target->mm_mapsize = pending->mm_mapsize;
target->mm_dbs[FREE_DBI] = pending->mm_dbs[FREE_DBI];
@ -3495,8 +3509,11 @@ static int mdbx_env_sync0(MDB_env *env, unsigned flags, MDB_meta *pending) {
target->mm_last_pg = pending->mm_last_pg;
target->mm_canary = pending->mm_canary;
/* LY: 'commit' the meta */
mdbx_jitter4testing(true);
target->mm_txnid = pending->mm_txnid;
mdbx_jitter4testing(true);
target->mm_datasync_sign = pending->mm_datasync_sign;
mdbx_jitter4testing(true);
} else {
pending->mm_magic = MDB_MAGIC;
pending->mm_version = MDB_DATA_VERSION;