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/sr-io/without_std.rs

@@ -283,6 +283,13 @@ extern_functions! {
 	fn ext_sr25519_verify(msg_data: *const u8, msg_len: u32, sig_data: *const u8, pubkey_data: *const u8) -> u32;
 	/// Note: ext_secp256k1_ecdsa_recover returns 0 if the signature is correct, nonzero otherwise.
 	fn ext_secp256k1_ecdsa_recover(msg_data: *const u8, sig_data: *const u8, pubkey_data: *mut u8) -> u32;
+
+	//================================
+	// Offchain-worker Context
+	//================================
+
+	/// Submit extrinsic.
+	fn ext_submit_extrinsic(data: *const u8, len: u32);
 }
 
 /// Ensures we use the right crypto when calling into native
@@ -594,6 +601,18 @@ pub fn secp256k1_ecdsa_recover(sig: &[u8; 65], msg: &[u8; 32]) -> Result<[u8; 64
 	}
 }
 
+/// Submit extrinsic from the runtime.
+///
+/// Depending on the kind of extrinsic it will either be:
+/// 1. scheduled to be included in the next produced block (inherent)
+/// 2. added to the pool and propagated (transaction)
+pub fn submit_extrinsic<T: codec::Encode>(data: &T) {
+	let encoded_data = codec::Encode::encode(data);
+	unsafe {
+		ext_submit_extrinsic.get()(encoded_data.as_ptr(), encoded_data.len() as u32)
+	}
+}
+
 /// Trait for things which can be printed.
 pub trait Printable {
 	fn print(self);