pub trait DbExternalities: Send {
// Required methods
fn local_storage_set(&mut self, kind: StorageKind, key: &[u8], value: &[u8]);
fn local_storage_clear(&mut self, kind: StorageKind, key: &[u8]);
fn local_storage_compare_and_set(
&mut self,
kind: StorageKind,
key: &[u8],
old_value: Option<&[u8]>,
new_value: &[u8],
) -> bool;
fn local_storage_get(
&mut self,
kind: StorageKind,
key: &[u8],
) -> Option<Vec<u8>>;
}Expand description
A externalities extension for accessing the Offchain DB.
Required Methods§
sourcefn local_storage_set(&mut self, kind: StorageKind, key: &[u8], value: &[u8])
fn local_storage_set(&mut self, kind: StorageKind, key: &[u8], value: &[u8])
Sets a value in the local storage.
Note this storage is not part of the consensus, it’s only accessible by offchain worker tasks running on the same machine. It is persisted between runs.
sourcefn local_storage_clear(&mut self, kind: StorageKind, key: &[u8])
fn local_storage_clear(&mut self, kind: StorageKind, key: &[u8])
Removes a value in the local storage.
Note this storage is not part of the consensus, it’s only accessible by offchain worker tasks running on the same machine. It is persisted between runs.
sourcefn local_storage_compare_and_set(
&mut self,
kind: StorageKind,
key: &[u8],
old_value: Option<&[u8]>,
new_value: &[u8],
) -> bool
fn local_storage_compare_and_set( &mut self, kind: StorageKind, key: &[u8], old_value: Option<&[u8]>, new_value: &[u8], ) -> bool
Sets a value in the local storage if it matches current value.
Since multiple offchain workers may be running concurrently, to prevent data races use CAS to coordinate between them.
Returns true if the value has been set, false otherwise.
Note this storage is not part of the consensus, it’s only accessible by offchain worker tasks running on the same machine. It is persisted between runs.
sourcefn local_storage_get(
&mut self,
kind: StorageKind,
key: &[u8],
) -> Option<Vec<u8>>
fn local_storage_get( &mut self, kind: StorageKind, key: &[u8], ) -> Option<Vec<u8>>
Gets a value from the local storage.
If the value does not exist in the storage None will be returned.
Note this storage is not part of the consensus, it’s only accessible by
offchain worker tasks running on the same machine. It is persisted between runs.