Trait sp_core::offchain::DbExternalities

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>>;
}

A externalities extension for accessing the Offchain DB.

Required Methods

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.

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.

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.

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.

Implementations on Foreign Types

impl<T: DbExternalities + ?Sized> DbExternalities for Box<T>

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>>

Implementors

impl DbExternalities for TestOffchainExt

impl<Storage: OffchainStorage> DbExternalities for OffchainDb<Storage>

impl<T: DbExternalities> DbExternalities for LimitedExternalities<T>