Refactor sr-api to not depend on client anymore (#4086)

* Refactor sr-api to not depend on client anymore

* Fix benches

* Apply suggestions from code review

Co-Authored-By: Tomasz Drwięga <tomusdrw@users.noreply.github.com>

* Apply suggestions from code review

substrate/core/offchain/Cargo.toml

@@ -8,7 +8,8 @@ edition = "2018"
 
 [dependencies]
 bytes = "0.4.12"
-client = { package = "substrate-client", path = "../../core/client" }
+client = { package = "substrate-client", path = "../client" }
+sr-api = { path = "../sr-api" }
 fnv = "1.0.6"
 futures01 = { package = "futures", version = "0.1" }
 futures-preview = "0.3.0-alpha.19"

substrate/core/offchain/primitives/Cargo.toml

@@ -7,12 +7,12 @@ authors = ["Parity Technologies <admin@parity.io>"]
 edition = "2018"
 
 [dependencies]
-client = { package = "substrate-client", path = "../../client", default-features = false }
+sr-api = { path = "../../sr-api", default-features = false }
 sr-primitives = {  path = "../../sr-primitives", default-features = false }
 
 [features]
 default = ["std"]
 std = [
-	"client/std",
+	"sr-api/std",
 	"sr-primitives/std"
 ]

substrate/core/offchain/primitives/src/lib.rs

@@ -19,13 +19,12 @@
 #![cfg_attr(not(feature = "std"), no_std)]
 #![warn(missing_docs)]
 
-use client::decl_runtime_apis;
 use sr_primitives::traits::NumberFor;
 
 /// Local Storage Prefix used by the Offchain Worker API to
 pub const STORAGE_PREFIX: &[u8] = b"storage";
 
-decl_runtime_apis! {
+sr_api::decl_runtime_apis! {
 	/// The offchain worker api.
 	pub trait OffchainWorkerApi {
 		/// Starts the off-chain task for given block number.

substrate/core/offchain/src/lib.rs

@@ -33,15 +33,11 @@
 
 #![warn(missing_docs)]
 
-use std::{
-	fmt,
-	marker::PhantomData,
-	sync::Arc,
-};
+use std::{fmt, marker::PhantomData, sync::Arc};
 
 use parking_lot::Mutex;
 use threadpool::ThreadPool;
-use client::runtime_api::ApiExt;
+use sr_api::ApiExt;
 use futures::future::Future;
 use log::{debug, warn};
 use network::NetworkStateInfo;
@@ -106,7 +102,7 @@ impl<Client, Storage, Block> OffchainWorkers<
 	) -> impl Future<Output = ()> where A: ChainApi<Block=Block> + 'static {
 		let runtime = self.client.runtime_api();
 		let at = BlockId::number(*number);
-		let has_api = runtime.has_api::<dyn OffchainWorkerApi<Block>>(&at);
+		let has_api = runtime.has_api::<dyn OffchainWorkerApi<Block, Error = ()>>(&at);
 		debug!("Checking offchain workers at {:?}: {:?}", at, has_api);
 
 		if has_api.unwrap_or(false) {