PEERSTORE — GNUnet documentation

# PEERSTORE

## libgnunetpeerstore

libgnunetpeerstore is the library containing the PEERSTORE API. Subsystems wishing to communicate with the PEERSTORE service use this API to open a connection to PEERSTORE. This is done by calling `GNUNET_PEERSTORE_connect` which returns a handle to the newly created connection. This handle has to be used with any further calls to the API.

To store a new record, the function `GNUNET_PEERSTORE_store` is to be used which requires the record fields and a continuation function that will be called by the API after the STORE request is sent to the PEERSTORE service. Note that calling the continuation function does not mean that the record is successfully stored, only that the STORE request has been successfully sent to the PEERSTORE service. `GNUNET_PEERSTORE_store_cancel` can be called to cancel the STORE request only before the continuation function has been called.

To iterate over stored records, the function `GNUNET_PEERSTORE_iterate` is to be used. peerid and key can be set to NULL. An iterator callback function will be called with each matching record found and a NULL record at the end to signal the end of result set. `GNUNET_PEERSTORE_iterate_cancel` can be used to cancel the ITERATE request before the iterator callback is called with a NULL record.

To be notified with new values stored under a (subsystem, peerid, key) combination, the function `GNUNET_PEERSTORE_watch` is to be used. This will register the watcher with the PEERSTORE service, any new records matching the given combination will trigger the callback function passed to `GNUNET_PEERSTORE_watch`. This continues until `GNUNET_PEERSTORE_watch_cancel` is called or the connection to the service is destroyed.

After the connection is no longer needed, the function `GNUNET_PEERSTORE_disconnect` can be called to disconnect from the PEERSTORE service. Any pending ITERATE or WATCH requests will be destroyed. If the `sync_first` flag is set to `GNUNET_YES`, the API will delay the disconnection until all pending STORE requests are sent to the PEERSTORE service, otherwise, the pending STORE requests will be destroyed as well.