olaf_db.h File Reference

Olaf fingerprint database. More...

#include <stdbool.h>
#include <stdint.h>

Go to the source code of this file.

Data Structures
struct	Olaf_Resource_Meta_data
	A struct containing meta data on indexed audio files. More...

Typedefs
typedef struct Olaf_DB	Olaf_DB
typedef struct Olaf_Resource_Meta_data	Olaf_Resource_Meta_data

Functions
Olaf_DB *	olaf_db_new (const char *db_file_folder, bool readonly)
void	olaf_db_destroy (Olaf_DB *db)
void	olaf_db_store_meta_data (Olaf_DB *db, uint32_t *key, Olaf_Resource_Meta_data *value)
void	olaf_db_find_meta_data (Olaf_DB *db, uint32_t *key, Olaf_Resource_Meta_data *value)
void	olaf_db_delete_meta_data (Olaf_DB *db, uint32_t *key)
bool	olaf_db_has_meta_data (Olaf_DB *db, uint32_t *key)
void	olaf_db_stats_meta_data (Olaf_DB *db, bool verbose)
void	olaf_db_store (Olaf_DB *db, uint64_t *keys, uint64_t *values, size_t size)
void	olaf_db_delete (Olaf_DB *db, uint64_t *keys, uint64_t *values, size_t size)
size_t	olaf_db_find (Olaf_DB *db, uint64_t start_key, uint64_t stop_key, uint64_t *results, size_t results_size)
bool	olaf_db_find_single (Olaf_DB *db, uint64_t start_key, uint64_t stop_key)
void	olaf_db_stats (Olaf_DB *db, bool verbose)
uint32_t	olaf_db_string_hash (const char *key, size_t len)

Detailed Description

Olaf fingerprint database.

The interface to a data store with fingerprints. There are two implementations included in Olaf. A persistent key value store backed by a B-tree (LMDB) or an in memory store.

The data store is a list of fingerprint hashes (uint64_t) pointing to a value (also uint64_t) The value consists of: *

• The 32 least significant bits (uint32_t) are an audio identifier
• The next 32 bits (uint32_t) a time stamp

Hash collisions are possible so duplicates should be allowed.

Function Documentation

olaf_db_delete()

void olaf_db_delete	(	Olaf_DB *	db,
		uint64_t *	keys,
		uint64_t *	values,
		size_t	size )

Delete a list of elements in the data store.

Parameters

db	The database.
keys	A list of keys: the 64bit fingerprint hash.
values	A list of values: Typically the highest 32bits contain a timestamp, the lowest 32bits an audio identifier.
size	The size of both the keys and values arrays.

olaf_db_delete_meta_data()

void olaf_db_delete_meta_data	(	Olaf_DB *	db,
		uint32_t *	key )

Delete meta-data.

Parameters

db	The database.
key	The audio identifier to delete meta-data for.-

olaf_db_destroy()

void olaf_db_destroy

(

Olaf_DB *

db

)

Free database related memory resources and close files or other resources.

Parameters

db	the database to close.

olaf_db_find()

size_t olaf_db_find	(	Olaf_DB *	db,
		uint64_t	start_key,
		uint64_t	stop_key,
		uint64_t *	results,
		size_t	results_size )

Find a list of elements in the database store

Parameters

db	The database.
start_key	The begin key to start returning results from.
stop_key	The end key, should be greater than start_key.
results	An array to store the results in.
results_size	the maximum size of the results array.

Returns

The number of found results

olaf_db_find_meta_data()

void olaf_db_find_meta_data	(	Olaf_DB *	db,
		uint32_t *	key,
		Olaf_Resource_Meta_data *	value )

Search meta-data.

Parameters

db	The database.
key	The audio identifier.
value	Where to store meta-data information on the audio.

olaf_db_find_single()

bool olaf_db_find_single	(	Olaf_DB *	db,
		uint64_t	start_key,
		uint64_t	stop_key )

Checks if a hash is present in the database.

Parameters

db	The database.
start_key	The begin key to start returning results from.
stop_key	The end key, should be greater than start_key.

Returns

The true if a hash in the range is present.

olaf_db_has_meta_data()

bool olaf_db_has_meta_data	(	Olaf_DB *	db,
		uint32_t *	key )

Check if there is meta data for a key.

Parameters

db	The database.
key	The audio identifier.

Returns

True if meta-data is available.

olaf_db_new()

Olaf_DB * olaf_db_new	(	const char *	db_file_folder,
		bool	readonly )

Creates a new database, if the file name exists, read the contents

Parameters

db_file_folder	The folder used to store database files
readonly	The mode to open the database, if no write operations are expected this should be true.

olaf_db_stats()

void olaf_db_stats	(	Olaf_DB *	db,
		bool	verbose )

Print database statistics.

Parameters

db	The database.
verbose	Print more information than usual.

olaf_db_stats_meta_data()

void olaf_db_stats_meta_data	(	Olaf_DB *	db,
		bool	verbose )

Print meta database statistics.

Parameters

db	The database.
verbose	Print more information than usual.

olaf_db_store()

void olaf_db_store	(	Olaf_DB *	db,
		uint64_t *	keys,
		uint64_t *	values,
		size_t	size )

Store a list of elements in the data store.

Parameters

db	The database.
keys	A list of keys: the 64bit fingerprint hash.
values	A list of values: Typically the highest 32bits contain a timestamp, the lowest 32bits an audio identifier.
size	The size of both the keys and values arrays.

olaf_db_store_meta_data()

void olaf_db_store_meta_data	(	Olaf_DB *	db,
		uint32_t *	key,
		Olaf_Resource_Meta_data *	value )

Store meta-data.

Parameters

db	The database to store info in.
key	The audio identifier.
value	The meta-data with information on the audio.

olaf_db_string_hash()

uint32_t olaf_db_string_hash	(	const char *	key,
		size_t	len )

Hash a string into a 32 bit integer e.g. using a Jenkins hash. This can be practial to convert an audio file name into an identifier.

Parameters

key	The list of characters.
len	The length of the string.