ISAR/libmdbx
3
0
Fork 0
mirror of https://github.com/isar/libmdbx.git synced 2025-01-20 10:58:21 +08:00
Code Issues Packages Projects Releases Wiki Activity

mdbx: more info about "one threat - one transaction".

Browse Source 
Change-Id: I070750b081e02113577dac13488d01f9d18e759b
This commit is contained in:
Leonid Yuriev 2020-02-02 02:41:32 +03:00
parent 49d9779c84
commit 01f65bc872
1 changed files with 16 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

16
mdbx.h
View File

@ -201,6 +201,14 @@
* necessary) in a child process would be both extreme complicated and so * necessary) in a child process would be both extreme complicated and so
* fragile. * 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 (MDBX_TXN_OVERLAPPING, MDBX_BAD_RSLOT, MDBX_BUSY)
* unless you using MDBX_NOTLS option on the environment. Nonetheless, with the
* MDBX_NOTLS 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 * 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, * Local Storage. If you want to pass read-only transactions across threads,
* you can use the MDBX_NOTLS option on the environment. Nevertheless, a write * you can use the MDBX_NOTLS option on the environment. Nevertheless, a write
@ -383,6 +391,14 @@
* belongs to one thread. The MDBX_NOTLS flag changes this for read-only * belongs to one thread. The MDBX_NOTLS flag changes this for read-only
* transactions. See below. * transactions. See below.
* *
* 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 (MDBX_TXN_OVERLAPPING, MDBX_BAD_RSLOT,
* MDBX_BUSY) unless you using MDBX_NOTLS option on the environment.
* Nonetheless, with the MDBX_NOTLS option, you must know exactly what you
* are doing, otherwise you will get deadlocks or reading an alien data.
*
* - Do not have open an MDBX database twice in the same process at the same * - Do not have open an MDBX database twice in the same process at the same
* time. By default MDBX prevent this in most cases by tracking databases * time. By default MDBX prevent this in most cases by tracking databases
* opening and return MDBX_BUSY if anyone LCK-file is already open. * opening and return MDBX_BUSY if anyone LCK-file is already open.