mdbx: more isolation MDBX/LMDB API.

mdbx.h

@@ -50,6 +50,11 @@
 #	define _GNU_SOURCE
 #endif
 
+/** @defgroup mdbx MDBX API
+ *	@{
+ *	@brief libmdbx - Extended version of LMDB
+ */
+
 #define mdb_version	mdbx_version
 #define mdb_strerror	mdbx_strerror
 #define mdb_env_create	mdbx_env_create
@@ -61,7 +66,6 @@
 #define mdb_env_copyfd2	mdbx_env_copyfd2
 #define mdb_env_sync	mdbx_env_sync
 #define mdb_env_close	mdbx_env_close
-#define mdb_env_close_ex	mdbx_env_close_ex
 #define mdb_env_set_flags	mdbx_env_set_flags
 #define mdb_env_get_flags	mdbx_env_get_flags
 #define mdb_env_get_path	mdbx_env_get_path
@@ -113,4 +117,104 @@
 
 #include "./lmdb.h"
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+int mdbx_env_open_ex(MDB_env *env, const char *path, unsigned flags, mode_t mode, int *exclusive);
+int mdbx_env_stat(MDB_env *env, MDBX_stat *stat, size_t bytes);
+int mdbx_stat(MDB_txn *txn, MDB_dbi dbi, MDBX_stat *stat, size_t bytes);
+int mdbx_env_info(MDB_env *env, MDBX_envinfo *info, size_t bytes);
+int mdbx_env_close_ex(MDB_env *env, int dont_sync);
+
+	/** @brief Set threshold to force flush the data buffers to disk,
+	 * even of #MDB_NOSYNC, #MDB_NOMETASYNC and #MDB_MAPASYNC flags
+	 * in the environment.
+	 *
+	 * Data is always written to disk when #mdb_txn_commit() is called,
+	 * but the operating system may keep it buffered. LMDB always flushes
+	 * the OS buffers upon commit as well, unless the environment was
+	 * opened with #MDB_NOSYNC or in part #MDB_NOMETASYNC.
+	 *
+	 * The default is 0, than mean no any threshold checked,
+	 * and no additional flush will be made.
+	 *
+	 * @param[in] env An environment handle returned by #mdb_env_create()
+	 * @param[in] bytes The size in bytes of summary changes
+	 * when a synchronous flush would be made.
+	 * @return A non-zero error value on failure and 0 on success.
+	 */
+int mdbx_env_set_syncbytes(MDB_env *env, size_t bytes);
+	/** @brief Returns a lag of the reading.
+	 *
+	 * Returns an information for estimate how much given read-only
+	 * transaction is lagging relative the to actual head.
+	 *
+	 * @param[in] txn A transaction handle returned by #mdb_txn_begin()
+	 * @param[out] percent Percentage of page allocation in the database.
+	 * @return Number of transactions committed after the given was started for read, or -1 on failure.
+	 */
+int mdbx_txn_straggler(MDB_txn *txn, int *percent);
+
+	/** @brief A callback function for killing a laggard readers,
+	 * but also could waiting ones. Called in case of MDB_MAP_FULL error.
+	 *
+	 * @param[in] env An environment handle returned by #mdb_env_create().
+	 * @param[in] pid pid of the reader process.
+	 * @param[in] thread_id thread_id of the reader thread.
+	 * @param[in] txn Transaction number on which stalled.
+	 * @param[in] gap a lag from the last commited txn.
+	 * @param[in] retry a retry number, less that zero for notify end of OOM-loop.
+	 * @return -1 on failure (reader is not killed),
+	 * 	0 on a race condition (no such reader),
+	 * 	1 on success (reader was killed),
+	 * 	>1 on success (reader was SURE killed).
+	 */
+typedef int (MDBX_oom_func)(MDB_env *env, int pid, void* thread_id, size_t txn, unsigned gap, int retry);
+
+	/** @brief Set the OOM callback.
+	 *
+	 * Callback will be called only on out-of-pages case for killing
+	 * a laggard readers to allowing reclaiming of freeDB.
+	 *
+	 * @param[in] env An environment handle returned by #mdb_env_create().
+	 * @param[in] oomfunc A #MDBX_oom_func function or NULL to disable.
+	 */
+void mdbx_env_set_oomfunc(MDB_env *env, MDBX_oom_func *oom_func);
+
+	/** @brief Get the current oom_func callback.
+	 *
+	 * Callback will be called only on out-of-pages case for killing
+	 * a laggard readers to allowing reclaiming of freeDB.
+	 *
+	 * @param[in] env An environment handle returned by #mdb_env_create().
+	 * @return A #MDBX_oom_func function or NULL if disabled.
+	 */
+MDBX_oom_func* mdbx_env_get_oomfunc(MDB_env *env);
+
+#define MDBX_DBG_ASSERT	1
+#define MDBX_DBG_PRINT	2
+#define MDBX_DBG_TRACE	4
+#define MDBX_DBG_EXTRA	8
+#define MDBX_DBG_AUDIT	16
+#define MDBX_DBG_EDGE	32
+
+/* LY: a "don't touch" value */
+#define MDBX_DBG_DNT	(-1L)
+
+typedef void MDBX_debug_func(int type, const char *function, int line,
+								  const char *msg, va_list args);
+
+int mdbx_setup_debug(int flags, MDBX_debug_func* logger, long edge_txn);
+
+typedef int MDBX_pgvisitor_func(size_t pgno, unsigned pgnumber, void* ctx,
+					const char* dbi, const char *type, int nentries,
+					int payload_bytes, int header_bytes, int unused_bytes);
+int mdbx_env_pgwalk(MDB_txn *txn, MDBX_pgvisitor_func* visitor, void* ctx);
+/**	@} */
+
+#ifdef __cplusplus
+}
+#endif
+
 #endif /* _MDBX_H_ */