Initial: Offchain Workers (#1942)

* Refactor state-machine stuff.

* Fix tests.

* WiP

* WiP2

* Service support for offchain workers.

* Service support for offchain workers.

* Testing offchain worker.

* Initial version working.

* Pass side effects in call.

* Pass OffchainExt in context.

* Submit extrinsics to the pool.

* Support inherents.

* Insert to inherents pool.

* Inserting to the pool asynchronously.

* Add test to offchain worker.

* Implement convenience syntax for modules.

* Dispatching offchain worker through executive.

* Fix offchain test.

* Remove offchain worker from timestamp.

* Update Cargo.lock.

* Address review comments.

* Use latest patch version for futures.

* Add CLI parameter for offchain worker.

* Fix compilation.

* Fix test.

* Fix extrinsics format for tests.

* Fix RPC test.

* Bump spec version.

* Fix executive.

* Fix support macro.

* Address grumbles.

* Bump runtime

substrate/core/primitives/src/lib.rs

@@ -76,6 +76,35 @@ pub use hash_db::Hasher;
 // pub use self::hasher::blake::BlakeHasher;
 pub use self::hasher::blake2::Blake2Hasher;
 
+/// Context for executing a call into the runtime.
+#[repr(u8)]
+pub enum ExecutionContext {
+	/// Context for general importing (including own blocks).
+	Importing,
+	/// Context used when syncing the blockchain.
+	Syncing,
+	/// Context used for block construction.
+	BlockConstruction,
+	/// Offchain worker context.
+	OffchainWorker(Box<OffchainExt>),
+	/// Context used for other calls.
+	Other,
+}
+
+/// An extended externalities for offchain workers.
+pub trait OffchainExt {
+	/// Submits an extrinsics.
+	///
+	/// The extrinsic will either go to the pool (signed)
+	/// or to the next produced block (inherent).
+	fn submit_extrinsic(&mut self, extrinsic: Vec<u8>);
+}
+impl<T: OffchainExt + ?Sized> OffchainExt for Box<T> {
+	fn submit_extrinsic(&mut self, ex: Vec<u8>) {
+		(&mut **self).submit_extrinsic(ex)
+	}
+}
+
 /// Hex-serialised shim for `Vec<u8>`.
 #[derive(PartialEq, Eq, Clone)]
 #[cfg_attr(feature = "std", derive(Serialize, Deserialize, Debug, Hash, PartialOrd, Ord))]