* access to locks and lock file. Exceptions: On read-only filesystems
* or with the #MDB_NOLOCK flag described under #mdb_env_open().
*
+ * - By default, in versions before 0.9.10, unused portions of the data
+ * file might receive garbage data from memory freed by other code.
+ * (This does not happen when using the #MDB_WRITEMAP flag.) As of
+ * 0.9.10 the default behavior is to initialize such memory before
+ * writing to the data file. Since there may be a slight performance
+ * cost due to this initialization, applications may disable it using
+ * the #MDB_NOMEMINIT flag. Applications handling sensitive data
+ * which must not be written should not use this flag. This flag is
+ * irrelevant when using #MDB_WRITEMAP.
+ *
* - A thread can only use one transaction at a time, plus any child
* transactions. Each transaction belongs to one thread. See below.
* The #MDB_NOTLS flag changes this for read-only transactions.
/** Library minor version */
#define MDB_VERSION_MINOR 9
/** Library patch version */
-#define MDB_VERSION_PATCH 9
+#define MDB_VERSION_PATCH 11
/** Combine args a,b,c into a single integer for easy version comparisons */
#define MDB_VERINT(a,b,c) (((a) << 24) | ((b) << 16) | (c))
MDB_VERINT(MDB_VERSION_MAJOR,MDB_VERSION_MINOR,MDB_VERSION_PATCH)
/** The release date of this library version */
-#define MDB_VERSION_DATE "October 24, 2013"
+#define MDB_VERSION_DATE "January 15, 2014"
/** A stringifier for the version info */
#define MDB_VERSTR(a,b,c,d) "MDB " #a "." #b "." #c ": (" d ")"
typedef void (MDB_rel_func)(MDB_val *item, void *oldptr, void *newptr, void *relctx);
/** @defgroup mdb_env Environment Flags
- *
- * Values do not overlap Database Flags.
* @{
*/
/** mmap at a fixed address (experimental) */
#define MDB_NOLOCK 0x400000
/** don't do readahead (no effect on Windows) */
#define MDB_NORDAHEAD 0x800000
+ /** don't initialize malloc'd memory before writing to datafile */
+#define MDB_NOMEMINIT 0x1000000
/** @} */
/** @defgroup mdb_dbi_open Database Flags
- *
- * Values do not overlap Environment Flags.
* @{
*/
/** use reverse string keys */
* supports it. Turning it off may help random read performance
* when the DB is larger than RAM and system RAM is full.
* The option is not implemented on Windows.
+ * <li>#MDB_NOMEMINIT
+ * Don't initialize malloc'd memory before writing to unused spaces
+ * in the data file. By default, memory for pages written to the data
+ * file is obtained using malloc. While these pages may be reused in
+ * subsequent transactions, freshly malloc'd pages will be initialized
+ * to zeroes before use. This avoids persisting leftover data from other
+ * code (that used the heap and subsequently freed the memory) into the
+ * data file. Note that many other system libraries may allocate
+ * and free memory from the heap for arbitrary uses. E.g., stdio may
+ * use the heap for file I/O buffers. This initialization step has a
+ * modest performance cost so some applications may want to disable
+ * it using this flag. This option can be a problem for applications
+ * which handle sensitive data like passwords, and it makes memory
+ * checkers like Valgrind noisy. This flag is not needed with #MDB_WRITEMAP,
+ * which writes directly to the mmap instead of using malloc for pages. The
+ * initialization is also skipped if #MDB_RESERVE is used; the
+ * caller is expected to overwrite all of the memory that was
+ * reserved in that case.
+ * This flag may be changed at any time using #mdb_env_set_flags().
* </ul>
* @param[in] mode The UNIX permissions to set on created files. This parameter
* is ignored on Windows.
*/
int mdb_env_set_maxdbs(MDB_env *env, MDB_dbi dbs);
- /** @brief Get the maximum size of a key for the environment.
+ /** @brief Get the maximum size of keys and #MDB_DUPSORT data we can write.
*
- * This is the compile-time constant #MDB_MAXKEYSIZE, default 511.
+ * Depends on the compile-time constant #MDB_MAXKEYSIZE. Default 511.
* See @ref MDB_val.
* @param[in] env An environment handle returned by #mdb_env_create()
- * @return The maximum size of a key
+ * @return The maximum size of a key we can write
*/
int mdb_env_get_maxkeysize(MDB_env *env);
+ /** @brief Set application information associated with the #MDB_env.
+ *
+ * @param[in] env An environment handle returned by #mdb_env_create()
+ * @param[in] ctx An arbitrary pointer for whatever the application needs.
+ * @return A non-zero error value on failure and 0 on success.
+ */
+int mdb_env_set_userctx(MDB_env *env, void *ctx);
+
+ /** @brief Get the application information associated with the #MDB_env.
+ *
+ * @param[in] env An environment handle returned by #mdb_env_create()
+ * @return The pointer set by #mdb_env_set_userctx().
+ */
+void *mdb_env_get_userctx(MDB_env *env);
+
+ /** @brief A callback function for most MDB assert() failures,
+ * called before printing the message and aborting.
+ *
+ * @param[in] env An environment handle returned by #mdb_env_create().
+ * @param[in] msg The assertion message, not including newline.
+ */
+typedef void MDB_assert_func(MDB_env *env, const char *msg);
+
+ /** Set or reset the assert() callback of the environment.
+ * Disabled if liblmdb is buillt with NDEBUG.
+ * @note This hack should become obsolete as lmdb's error handling matures.
+ * @param[in] env An environment handle returned by #mdb_env_create().
+ * @parem[in] func An #MDB_assert_func function, or 0.
+ * @return A non-zero error value on failure and 0 on success.
+ */
+int mdb_env_set_assert(MDB_env *env, MDB_assert_func *func);
+
/** @brief Create a transaction for use with the environment.
*
* The transaction handle may be discarded using #mdb_txn_abort() or #mdb_txn_commit().
* reserved space, which the caller can fill in later - before
* the next update operation or the transaction ends. This saves
* an extra memcpy if the data is being generated later.
+ * MDB does nothing else with this memory, the caller is expected
+ * to modify all of the space requested.
* <li>#MDB_APPEND - append the given key/data pair to the end of the
* database. No key comparisons are performed. This option allows
* fast bulk loading when keys are already known to be in the
*
* @param[in] msg The string to be printed.
* @param[in] ctx An arbitrary context pointer for the callback.
- * @return < 0 on failure, 0 on success.
+ * @return < 0 on failure, >= 0 on success.
*/
typedef int (MDB_msg_func)(const char *msg, void *ctx);
* @param[in] env An environment handle returned by #mdb_env_create()
* @param[in] func A #MDB_msg_func function
* @param[in] ctx Anything the message function needs
- * @return < 0 on failure, 0 on success.
+ * @return < 0 on failure, >= 0 on success.
*/
int mdb_reader_list(MDB_env *env, MDB_msg_func *func, void *ctx);
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