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mdbx: rework API and Docs around Handle-Slow-Readers (no algorithmic changes).

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Change-Id: I5b76a8400ce6f5f241f8e4a7f53d746fe39f8e1e
This commit is contained in:
Leonid Yuriev
2020-09-29 19:24:57 +03:00
parent 6294e1710a
commit c8a0951566
12 changed files with 124 additions and 90 deletions
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27
mdbx.h++
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@@ -2100,14 +2100,16 @@ public:
/// return number of cleared slots.
inline unsigned check_readers();
/// \brief Sets the out-of-space callback.
/// \brief Sets a Handle-Slow-Readers callback to resolve database
/// full/overflow issue due to a reader(s) which prevents the old data from
/// being recycled.
///
/// Such callback will be triggered in a case where there is not enough free
/// space in the database due to long read transaction(s) which impedes
/// reusing the pages of an old MVCC snapshot(s).
///
/// Using this callback you can choose how to get out of the situation:
/// - abort the record transaction with an error;
/// Using this callback you can choose how to resolve the situation:
/// - abort the write transaction with an error;
/// - wait for the read transaction(s) to complete;
/// - notify a thread performing a long-lived read transaction
/// and wait for an effect;
@@ -2115,10 +2117,13 @@ public:
/// transaction;
///
/// \see long-lived-read
inline env &set_OutOfSpace_callback(MDBX_oom_func *);
/// \brief Returns the current out-of-space callback.
/// \see set_OutOfSpace_callback()
inline MDBX_oom_func *get_OutOfSpace_callback() const noexcept;
inline env &set_HandleSlowReaders(MDBX_hsr_func *);
/// \brief Returns the current Handle-Slow-Readers callback used to resolve
/// database full/overflow issue due to a reader(s) which prevents the old
/// data from being recycled.
/// \see set_HandleSlowReaders()
inline MDBX_hsr_func *get_HandleSlowReaders() const noexcept;
/// \brief Starts read (read-only) transaction.
inline txn_managed start_read() const;
@@ -3499,13 +3504,13 @@ inline unsigned env::check_readers() {
return static_cast<unsigned>(dead_count);
}
inline env &env::set_OutOfSpace_callback(MDBX_oom_func *cb) {
error::success_or_throw(::mdbx_env_set_oomfunc(handle_, cb));
inline env &env::set_HandleSlowReaders(MDBX_hsr_func *cb) {
error::success_or_throw(::mdbx_env_set_hsr(handle_, cb));
return *this;
}
inline MDBX_oom_func *env::get_OutOfSpace_callback() const noexcept {
return ::mdbx_env_get_oomfunc(handle_);
inline MDBX_hsr_func *env::get_HandleSlowReaders() const noexcept {
return ::mdbx_env_get_hsr(handle_);
}
inline txn_managed env::start_read() const {