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mdbx: добавление режима MDBX_NOSTICKYTHREADS вместо MDBX_NOTLS.

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Леонид Юрьев (Leonid Yuriev)
2024-04-02 00:22:09 +03:00
parent 1727b697a0
commit e56c73b4e6
14 changed files with 283 additions and 198 deletions
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docs/_starting.md
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@@ -129,20 +129,23 @@ no open MDBX-instance(s) during fork(), or at least close it immediately after
necessary) in a child process would be both extreme complicated and so
fragile.
Do not start more than one transaction for a one thread. If you think about
this, it's really strange to do something with two data snapshots at once,
which may be different. MDBX checks and preventing this by returning
corresponding error code (\ref MDBX_TXN_OVERLAPPING, \ref MDBX_BAD_RSLOT, \ref MDBX_BUSY)
unless you using \ref MDBX_NOTLS option on the environment. Nonetheless, with the
\ref MDBX_NOTLS option, you must know exactly what you are doing, otherwise you
will get deadlocks or reading an alien data.
Do not start more than one transaction for a one thread. If you think
about this, it's really strange to do something with two data snapshots
at once, which may be different. MDBX checks and preventing this by
returning corresponding error code (\ref MDBX_TXN_OVERLAPPING,
\ref MDBX_BAD_RSLOT, \ref MDBX_BUSY) unless you using
\ref MDBX_NOSTICKYTHREADS option on the environment. Nonetheless,
with the \ref MDBX_NOSTICKYTHREADS option, you must know exactly what
you are doing, otherwise you will get deadlocks or reading an alien
data.
Also note that a transaction is tied to one thread by default using Thread
Local Storage. If you want to pass read-only transactions across threads,
you can use the \ref MDBX_NOTLS option on the environment. Nevertheless, a write
transaction entirely should only be used in one thread from start to finish.
MDBX checks this in a reasonable manner and return the \ref MDBX_THREAD_MISMATCH
error in rules violation.
Also note that a transaction is tied to one thread by default using
Thread Local Storage. If you want to pass transactions across threads,
you can use the \ref MDBX_NOSTICKYTHREADS option on the environment.
Nevertheless, a write transaction must be committed or aborted in the
same thread which it was started. MDBX checks this in a reasonable
manner and return the \ref MDBX_THREAD_MISMATCH error in rules
violation.
## Transactions, rollbacks etc