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mdbx: add mdbx_thread_register() and mdbx_thread_unregister().

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Change-Id: I605bc75a20631e781043fafcc26f5e59cb40adaa
This commit is contained in:
Leonid Yuriev
2020-07-30 01:17:03 +03:00
parent b91918b027
commit 0a01b46112
3 changed files with 184 additions and 65 deletions
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38
mdbx.h
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@@ -3605,8 +3605,7 @@ LIBMDBX_API int mdbx_reader_list(const MDBX_env *env,
* \param [out] dead Number of stale slots that were cleared.
*
* \returns A non-zero error value on failure and 0 on success,
* or \ref MDBX_RESULT_TRUE if a dead reader(s) found or mutex was recovered.
*/
* or \ref MDBX_RESULT_TRUE if a dead reader(s) found or mutex was recovered. */
LIBMDBX_API int mdbx_reader_check(MDBX_env *env, int *dead);
/** Returns a lag of the reading for the given transaction.
@@ -3624,6 +3623,41 @@ LIBMDBX_API int mdbx_reader_check(MDBX_env *env, int *dead);
MDBX_DEPRECATED LIBMDBX_API int mdbx_txn_straggler(const MDBX_txn *txn,
int *percent);
/** Registers the current thread as a reader for the environment.
* \ingroup c_extra
*
* To perform read operations without blocking, a reader slot must be assigned
* for each thread. However, this assignment requires a short-term lock
* acquisition which is performed automatically. This function allows you to
* assign the reader slot in advance and thus avoid capturing the blocker when
* the read transaction starts firstly from current thread.
* \see mdbx_thread_unregister()
*
* \note Threads are registered automatically the first time a read transaction
* starts. Therefore, there is no need to use this function, except in
* special cases.
*
* \param [in] env An environment handle returned by \ref mdbx_env_create().
*
* \returns A non-zero error value on failure and 0 on success,
* or \ref MDBX_RESULT_TRUE if thread is already registered. */
LIBMDBX_API int mdbx_thread_register(MDBX_env *env);
/** Unregisters the current thread as a reader for the environment.
* \ingroup c_extra
*
* To perform read operations without blocking, a reader slot must be assigned
* for each thread. However, the assigned reader slot will remain occupied until
* the thread ends or the environment closes. This function allows you to
* explicitly release the assigned reader slot.
* \see mdbx_thread_register()
*
* \param [in] env An environment handle returned by \ref mdbx_env_create().
*
* \returns A non-zero error value on failure and 0 on success, or
* \ref MDBX_RESULT_TRUE if thread is not registered or already undegistered. */
LIBMDBX_API int mdbx_thread_unregister(MDBX_env *env);
/** A lack-of-space callback function to resolve issues with a laggard readers.
* \ingroup c_err
*