API description

Read blob data

Through the API of KVDB and TSDB, the blob object can be returned, and the storage address of the blob data is stored in the returned blob object. This API can read the blob data stored in the database and store it in blob->buf.

size_t fdb_blob_read(fdb_db_t db, fdb_blob_t blob)

Initialize KVDB

fdb_err_t fdb_kvdb_init(fdb_kvdb_t db, const char *name, const char *path, struct fdb_default_kv *default_kv, void *user_data)

Control KVDB

Through the command control word, the user can perform some control operations on the database

void fdb_kvdb_control(fdb_kvdb_t db, int cmd, void *arg)

The supported command control words are as follows:

Sector size and block size

The internal storage structure of FlashDB is composed of N sectors, and each formatting takes sector as the smallest unit. A sector is usually N times the size of the Flash block. For example, the block size of Nor Flash is generally 4096.

By default, KVDB will use 1 times the block size as the sector size, that is, 4096. At this time, the KVDB cannot store a KV longer than 4096. If you want to save, for example, a KV with a length of 10K, you can use the control function to set the sector size to 12K or larger.

Deinitialize KVDB

fdb_err_t fdb_kvdb_deinit(fdb_kvdb_t db)

Set KV

This method can be used to increase and modify KV.

• Add: When there is no KV with this name in KVDB, the new operation will be performed;

• Modify: The KV name in the input parameter exists in the current KVDB, then the KV value is modified to the value in the input parameter;

Get the corresponding value by KV’s name. Support two interfaces

Set blob type KV

fdb_err_t fdb_kv_set_blob(fdb_kvdb_t db, const char *key, fdb_blob_t blob)

Set string type KV

fdb_err_t fdb_kv_set(fdb_kvdb_t db, const char *key, const char *value)

Get KV

Get blob type KV

size_t fdb_kv_get_blob(fdb_kvdb_t db, const char *key, fdb_blob_t blob)

Example:

Get KV object

Unlike the fdb_kv_get_blob API, this API does not execute the reading of value data during the get process. The returned KV object stores the read KV attributes. This API is suitable for scenarios where the length of the value is uncertain, or the length of the value is too long, and it needs to be read in segments.

Get string type KV

Note:

• This function is not allowed to be used continuously, and strdup should be used when using it to ensure that the memory space of the string returned each time is independent;

char *fdb_kv_get(fdb_kvdb_t db, const char *key)

fdb_err_t fdb_kv_del(fdb_kvdb_t db, const char *key)

Reset KVDB

Reset the KV in KVDB to the first initial default value

fdb_err_t fdb_kv_set_default(fdb_kvdb_t db)

Print KV information in KVDB

void fdb_kv_print(fdb_kvdb_t db)

Convert KV objects to blob objects

fdb_blob_t fdb_kv_to_blob(fdb_kv_t kv, fdb_blob_t blob)

Initialize KV iterator

fdb_kv_iterator_t fdb_kv_iterator_init(fdb_kv_iterator_t itr)

Iteration KV

Using this iterator API, all KVs in the entire KVDB can be traversed.

Initialize TSDB

Through the command control word, the user can perform some control operations on the database

void fdb_tsdb_control(fdb_tsdb_t db, int cmd, void *arg)

The supported command control words are as follows:

Deinitialize TSDB

fdb_err_t fdb_tsdb_deinit(fdb_tsdb_t db)

Append TSL

For TSDB, the process of adding TSL is the process of appending a new TSL to the end of TSDB

fdb_err_t fdb_tsl_append(fdb_tsdb_t db, fdb_blob_t blob)

Iterative TSL

Traverse the entire TSDB and execute iterative callbacks

void fdb_tsl_iter(fdb_tsdb_t db, fdb_tsl_cb cb, void *cb_arg)

Iterate TSL by time period

According to the time range, traverse the entire TSDB and execute iterative callbacks

void fdb_tsl_iter_by_time(fdb_tsdb_t db, fdb_time_t from, fdb_time_t to, fdb_tsl_cb cb, void *cb_arg)

Query the number of TSL

According to the incoming time period, query the number of TSLs that meet the state size_t fdb_tsl_query_count(fdb_tsdb_t db, fdb_time_t from, fdb_time_t to, fdb_tsl_status_t status)

Set TSL status

For TSL status, please refer to enum fdb_tsl_status. TSL status MUST be set in order.

fdb_err_t fdb_tsl_set_status(fdb_tsdb_t db, fdb_tsl_t tsl, fdb_tsl_status_t status)

void fdb_tsl_clean(fdb_tsdb_t db)

Convert TSL objects to blob objects