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https://github.com/isar/libmdbx.git
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mdbx: add MDBX_TXN_RDONLY_PREPARE.
Change-Id: I95647d1679b69d1e97514a45f20d7373174244d5
This commit is contained in:
Leonid Yuriev
parent
1e7a1da14e
commit
87de3fc25f
8
mdbx.h
8
mdbx.h
@ -1010,6 +1010,14 @@ enum MDBX_txn_flags_t {
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* block each other and a write transactions. */
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MDBX_TXN_RDONLY = MDBX_RDONLY,
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/** Prepare but not start readonly transaction.
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*
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* Transaction will not be started immediately, but created transaction handle
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* will be ready for use with \ref mdbx_txn_renew(). This flag allows to
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* preallocate memory and assign a reader slot, thus avoiding these operations
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* at the next start of the transaction. */
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MDBX_TXN_RDONLY_PREPARE = MDBX_TXN_RDONLY | MDBX_NOMEMINIT,
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/** Do not block when starting a write transaction. */
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MDBX_TXN_TRY = UINT32_C(0x10000000),
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59
src/core.c
59
src/core.c
@ -5909,8 +5909,6 @@ typedef struct {
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static bind_rslot_result bind_rslot(MDBX_env *env, const uintptr_t tid) {
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mdbx_assert(env, env->me_lck);
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mdbx_assert(env, (env->me_flags & (MDBX_NOTLS | MDBX_ENV_TXKEY)) ==
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MDBX_ENV_TXKEY);
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mdbx_assert(env, env->me_lck->mti_magic_and_version == MDBX_LOCK_MAGIC);
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mdbx_assert(env, env->me_lck->mti_os_and_format == MDBX_LOCK_FORMAT);
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@ -6043,7 +6041,7 @@ __cold int mdbx_thread_unregister(MDBX_env *env) {
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}
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/* Common code for mdbx_txn_begin() and mdbx_txn_renew(). */
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static int mdbx_txn_renew0(MDBX_txn *txn, unsigned flags) {
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static int mdbx_txn_renew0(MDBX_txn *txn, const unsigned flags) {
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MDBX_env *env = txn->mt_env;
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int rc;
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@ -6067,10 +6065,9 @@ static int mdbx_txn_renew0(MDBX_txn *txn, unsigned flags) {
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STATIC_ASSERT(offsetof(MDBX_lockinfo, mti_readers) % MDBX_CACHELINE_SIZE ==
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0);
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mdbx_assert(env, (flags & ~(MDBX_TXN_BEGIN_FLAGS | MDBX_TXN_SPILLS |
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MDBX_WRITEMAP)) == 0);
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const uintptr_t tid = mdbx_thread_self();
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if (flags & MDBX_TXN_RDONLY) {
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mdbx_assert(env, (flags & ~(MDBX_TXN_RO_BEGIN_FLAGS | MDBX_WRITEMAP)) == 0);
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txn->mt_flags =
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MDBX_TXN_RDONLY | (env->me_flags & (MDBX_NOTLS | MDBX_WRITEMAP));
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MDBX_reader *r = txn->to.reader;
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@ -6096,6 +6093,17 @@ static int mdbx_txn_renew0(MDBX_txn *txn, unsigned flags) {
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return brs.err;
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r = brs.rslot;
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}
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txn->to.reader = r;
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if (flags & (MDBX_TXN_RDONLY_PREPARE - MDBX_TXN_RDONLY)) {
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mdbx_assert(env, r->mr_txnid.inconsistent >= SAFE64_INVALID_THRESHOLD);
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mdbx_assert(env, txn->mt_txnid == 0);
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mdbx_assert(env, txn->mt_owner == 0);
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mdbx_assert(env, txn->mt_numdbs == 0);
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mdbx_assert(env, r->mr_snapshot_pages_used == 0);
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r->mr_snapshot_pages_used = 0;
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txn->mt_flags = MDBX_TXN_RDONLY | MDBX_TXN_FINISHED;
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return MDBX_SUCCESS;
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}
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/* Seek & fetch the last meta */
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while (1) {
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@ -6142,12 +6150,13 @@ static int mdbx_txn_renew0(MDBX_txn *txn, unsigned flags) {
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goto bailout;
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}
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mdbx_assert(env, txn->mt_txnid >= *env->me_oldest);
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txn->to.reader = r;
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txn->mt_dbxs = env->me_dbxs; /* mostly static anyway */
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mdbx_ensure(env, txn->mt_txnid >=
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/* paranoia is appropriate here */ *env->me_oldest);
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txn->mt_numdbs = env->me_numdbs;
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} else {
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mdbx_assert(env, (flags & ~(MDBX_TXN_RW_BEGIN_FLAGS | MDBX_TXN_SPILLS |
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MDBX_WRITEMAP)) == 0);
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if (unlikely(txn->mt_owner == tid))
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return MDBX_BUSY;
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MDBX_lockinfo *const lck = env->me_lck;
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@ -6352,24 +6361,21 @@ int mdbx_txn_begin(MDBX_env *env, MDBX_txn *parent, unsigned flags,
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return MDBX_EINVAL;
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*ret = NULL;
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if (unlikely((flags & ~MDBX_TXN_RW_BEGIN_FLAGS) &&
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(flags & ~MDBX_TXN_RO_BEGIN_FLAGS)))
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return MDBX_EINVAL;
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int rc = check_env(env);
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if (unlikely(rc != MDBX_SUCCESS))
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return rc;
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#if !defined(_WIN32) && !defined(_WIN64)
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/* Don't check env->me_map until lock to
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* avoid race with re-mapping for shrinking */
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if (unlikely(!env->me_map))
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return MDBX_EPERM;
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#endif /* Windows */
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if (unlikely(flags & ~MDBX_TXN_BEGIN_FLAGS))
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return MDBX_EINVAL;
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if (unlikely(env->me_flags & MDBX_RDONLY &
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~flags)) /* write txn in RDONLY env */
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return MDBX_EACCESS;
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if (unlikely(!env->me_map))
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return MDBX_EPERM;
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flags |= env->me_flags & MDBX_WRITEMAP;
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if (parent) {
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@ -6379,12 +6385,7 @@ int mdbx_txn_begin(MDBX_env *env, MDBX_txn *parent, unsigned flags,
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if (unlikely(rc != MDBX_SUCCESS))
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return rc;
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#if defined(_WIN32) || defined(_WIN64)
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if (unlikely(!env->me_map))
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return MDBX_EPERM;
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#endif /* Windows */
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flags |= parent->mt_flags & (MDBX_TXN_BEGIN_FLAGS | MDBX_TXN_SPILLS);
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flags |= parent->mt_flags & (MDBX_TXN_RW_BEGIN_FLAGS | MDBX_TXN_SPILLS);
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/* Child txns save MDBX_pgstate and use own copy of cursors */
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size = env->me_maxdbs * (sizeof(MDBX_db) + sizeof(MDBX_cursor *) + 1);
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size += tsize = sizeof(MDBX_txn);
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@ -6477,10 +6478,16 @@ int mdbx_txn_begin(MDBX_env *env, MDBX_txn *parent, unsigned flags,
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if (txn != env->me_txn0)
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mdbx_free(txn);
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} else {
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mdbx_assert(env,
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(txn->mt_flags & ~(MDBX_NOTLS | MDBX_TXN_RDONLY |
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MDBX_WRITEMAP | MDBX_SHRINK_ALLOWED |
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MDBX_NOMETASYNC | MDBX_SAFE_NOSYNC)) == 0);
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if (flags & (MDBX_TXN_RDONLY_PREPARE - MDBX_TXN_RDONLY))
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mdbx_assert(env, txn->mt_flags == (MDBX_TXN_RDONLY | MDBX_TXN_FINISHED));
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else if (flags & MDBX_TXN_RDONLY)
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mdbx_assert(env, (txn->mt_flags &
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~(MDBX_NOTLS | MDBX_TXN_RDONLY | MDBX_WRITEMAP |
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/* Win32: SRWL flag */ MDBX_SHRINK_ALLOWED)) == 0);
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else
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mdbx_assert(env,
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(txn->mt_flags & ~(MDBX_WRITEMAP | MDBX_SHRINK_ALLOWED |
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MDBX_NOMETASYNC | MDBX_SAFE_NOSYNC)) == 0);
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txn->mt_signature = MDBX_MT_SIGNATURE;
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*ret = txn;
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mdbx_debug("begin txn %" PRIaTXN "%c %p on env %p, root page %" PRIaPGNO
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@ -720,8 +720,9 @@ struct MDBX_txn {
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/* Transaction Flags */
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/* mdbx_txn_begin() flags */
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#define MDBX_TXN_BEGIN_FLAGS \
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(MDBX_TXN_NOMETASYNC | MDBX_TXN_NOSYNC | MDBX_TXN_RDONLY | MDBX_TXN_TRY)
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#define MDBX_TXN_RO_BEGIN_FLAGS (MDBX_TXN_RDONLY | MDBX_TXN_RDONLY_PREPARE)
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#define MDBX_TXN_RW_BEGIN_FLAGS \
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(MDBX_TXN_NOMETASYNC | MDBX_TXN_NOSYNC | MDBX_TXN_TRY)
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/* Additional flag for mdbx_sync_locked() */
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#define MDBX_SHRINK_ALLOWED UINT32_C(0x40000000)
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@ -739,8 +740,9 @@ struct MDBX_txn {
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(MDBX_TXN_FINISHED | MDBX_TXN_ERROR | MDBX_TXN_DIRTY | MDBX_TXN_SPILLS | \
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MDBX_TXN_HAS_CHILD)
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#if (TXN_FLAGS & MDBX_TXN_BEGIN_FLAGS) || \
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((MDBX_TXN_BEGIN_FLAGS | TXN_FLAGS) & MDBX_SHRINK_ALLOWED)
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#if (TXN_FLAGS & (MDBX_TXN_RW_BEGIN_FLAGS | MDBX_TXN_RO_BEGIN_FLAGS)) || \
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((MDBX_TXN_RW_BEGIN_FLAGS | MDBX_TXN_RO_BEGIN_FLAGS | TXN_FLAGS) & \
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MDBX_SHRINK_ALLOWED)
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#error "Oops, some flags overlapped or wrong"
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#endif
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