Persistent Local Storage for offchain workers. (#2894)

* WiP.

* Implement offchain storage APIs.

* Change compare_and_set to return bool.

* Add offchain http test.

* Fix tests.

* Bump spec version.

* Fix warnings and test.

* Fix compilation.

* Remove unused code.

* Introduce Local (fork-aware) and Persistent storage.

* Fix borked merge.

* Prevent warning on depreacated client.backend

* Fix long lines.

* Clean up dependencies.

* Update core/primitives/src/offchain.rs

Co-Authored-By: André Silva <andre.beat@gmail.com>

* Update core/primitives/src/offchain.rs

Co-Authored-By: André Silva <andre.beat@gmail.com>

substrate/core/service/src/components.rs

@@ -121,6 +121,11 @@ pub type ComponentClient<C> = Client<
 	<C as Components>::RuntimeApi,
 >;
 
+/// A offchain workers storage backend type.
+pub type ComponentOffchainStorage<C> = <
+	<C as Components>::Backend as client::backend::Backend<ComponentBlock<C>, Blake2Hasher>
+>::OffchainStorage;
+
 /// Block type for `Components`
 pub type ComponentBlock<C> = <<C as Components>::Factory as ServiceFactory>::Block;
 
@@ -259,7 +264,11 @@ impl<C: Components> MaintainTransactionPool<Self> for C where
 pub trait OffchainWorker<C: Components> {
 	fn offchain_workers(
 		number: &FactoryBlockNumber<C::Factory>,
-		offchain: &offchain::OffchainWorkers<ComponentClient<C>, ComponentBlock<C>>,
+		offchain: &offchain::OffchainWorkers<
+			ComponentClient<C>,
+			ComponentOffchainStorage<C>,
+			ComponentBlock<C>
+		>,
 		pool: &Arc<TransactionPool<C::TransactionPoolApi>>,
 	) -> error::Result<Box<dyn Future<Item = (), Error = ()> + Send>>;
 }
@@ -270,7 +279,11 @@ impl<C: Components> OffchainWorker<Self> for C where
 {
 	fn offchain_workers(
 		number: &FactoryBlockNumber<C::Factory>,
-		offchain: &offchain::OffchainWorkers<ComponentClient<C>, ComponentBlock<C>>,
+		offchain: &offchain::OffchainWorkers<
+			ComponentClient<C>,
+			ComponentOffchainStorage<C>,
+			ComponentBlock<C>
+		>,
 		pool: &Arc<TransactionPool<C::TransactionPoolApi>>,
 	) -> error::Result<Box<dyn Future<Item = (), Error = ()> + Send>> {
 		Ok(Box::new(offchain.on_block_imported(number, pool)))

substrate/core/service/src/lib.rs

@@ -32,7 +32,7 @@ use std::time::Duration;
 use futures::sync::mpsc;
 use parking_lot::Mutex;
 
-use client::{BlockchainEvents, backend::Backend};
+use client::{BlockchainEvents, backend::Backend, runtime_api::BlockT};
 use exit_future::Signal;
 use futures::prelude::*;
 use keystore::Store as Keystore;
@@ -51,11 +51,10 @@ pub use chain_spec::{ChainSpec, Properties};
 pub use transaction_pool::txpool::{
 	self, Pool as TransactionPool, Options as TransactionPoolOptions, ChainApi, IntoPoolError
 };
-use client::runtime_api::BlockT;
 pub use client::FinalityNotifications;
 
 pub use components::{ServiceFactory, FullBackend, FullExecutor, LightBackend,
-	LightExecutor, Components, PoolApi, ComponentClient,
+	LightExecutor, Components, PoolApi, ComponentClient, ComponentOffchainStorage,
 	ComponentBlock, FullClient, LightClient, FullComponents, LightComponents,
 	CodeExecutor, NetworkService, FactoryChainSpec, FactoryBlock,
 	FactoryFullConfiguration, RuntimeGenesis, FactoryGenesis,
@@ -94,8 +93,12 @@ pub struct Service<Components: components::Components> {
 	pub config: FactoryFullConfiguration<Components::Factory>,
 	_rpc: Box<dyn std::any::Any + Send + Sync>,
 	_telemetry: Option<tel::Telemetry>,
-	_offchain_workers: Option<Arc<offchain::OffchainWorkers<ComponentClient<Components>, ComponentBlock<Components>>>>,
 	_telemetry_on_connect_sinks: Arc<Mutex<Vec<mpsc::UnboundedSender<()>>>>,
+	_offchain_workers: Option<Arc<offchain::OffchainWorkers<
+		ComponentClient<Components>,
+		ComponentOffchainStorage<Components>,
+		ComponentBlock<Components>>
+	>>,
 }
 
 /// Creates bare client without any networking.
@@ -234,10 +237,20 @@ impl<Components: components::Components> Service<Components> {
 			.select(exit.clone())
 			.then(|_| Ok(()))));
 
-		let offchain_workers =  if config.offchain_worker {
-			Some(Arc::new(offchain::OffchainWorkers::new(client.clone())))
-		} else {
-			None
+		#[allow(deprecated)]
+		let offchain_storage = client.backend().offchain_storage();
+		let offchain_workers = match (config.offchain_worker, offchain_storage) {
+			(true, Some(db)) => {
+				Some(Arc::new(offchain::OffchainWorkers::new(
+					client.clone(),
+					db,
+				)))
+			},
+			(true, None) => {
+				log::warn!("Offchain workers disabled, due to lack of offchain storage support in backend.");
+				None
+			},
+			_ => None,
 		};
 
 		{