rpc: Implement chainHead RPC API (#12544)

* rpc/chain_head: Add event structure for serialization

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* rpc/chain_head: Add tests for events

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* rpc/chain_head: Add API trait for `chainHead`

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* rpc/chain_head: Add RPC errors

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* rpc/chain_head: Manage subscription ID tracking for pinned blocks

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* rpc/chain_head: Add tests for subscription management

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* rpc/chain_head: Constructor for the API

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* rpc/chain_head: Placeholders for API implementation

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* rpc/chain_head: Accept RPC subscription sink

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* rpc/chain_head: Generate the runtime API event

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* rpc/chain_head: Implement the `follow` method

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* rpc/chain_head: Implement the `body` method

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* rpc/chain_head: Implement the `header` method

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* rpc/chain_head: Implement the `storage` method

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* rpc/chain_head: Implement the `call` method

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* rpc/chain_head: Implement the `unpin` method

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* Update `Cargo.lock`

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* rpc/chain_head: Implement `getGenesis` method

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* rpc/chain_head: Fix clippy

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* rpc/chain_head: Parse params from hex string

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* rpc/chain_head: Constuct API with genesis hash

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* rpc/chain_head: Add the finalized block to reported tree route

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* rpc/chain_head: Export the API and events for better ergonomics

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* chain_head/tests: Add test module with helper functions

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* chain_head/tests: Test block events from the `follow` pubsub

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* chain_head/tests: Test `genesisHash` getter

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* chain_head/tests: Test `header` method

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* chain_head/tests: Test `body` method

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* chain_head/tests: Test calling into the runtime API

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* chain_head/tests: Test runtime for the `follow` method

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* chain_head/tests: Add runtime code changes for `follow` method

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* rpc/chain_head: Remove space from rustdoc

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* rpc/chain_head: Use the `child_key` for storage queries

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* rpc/chain_head: Test `storage` method

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* rpc/chain_head: Test child trie query for `storage` method

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* rpc/chain_head: Event serialization typo

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* rpc/chain_head: Remove subscription aliases

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* rpc/chain_head: Add `NetworkConfig` parameter

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* rpc/chain_head: Named parameters as camelCase if present

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* rpc/chain_head: Implement From<ApiError> for RuntimeEvents

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* rpc/chain_head: Handle pruning of the best block in finalization window

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* rpc/chain_head: Generate initial block events

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* chain_head/tests: Verify that initial in-memory blocks are reported

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* chain_head/tests: Verify the finalized event with forks and pruned blocks

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* rpc/chain_head: Fix clippy

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* rpc/chain_head: Separate logic for generating initial events

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* rpc/chain_head: Handle stopping a subscription ID

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* rpc/chain_head: Submit events until the "Stop" event is triggered

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* rpc/chain_head: Separate logic for handling new and finalized blocks

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* rpc/chain_head: Extend subscription logic with subId handle

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* rpc/chain_head: Adjust to the new subscription mngmt API

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* rpc/chain_head: Refuse RuntimeAPI calls without the runtime flag

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* chain_head/tests: Verify RuntimeAPI calls without runtime flag

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* rpc/chain_head: Add best block per subscription

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* rpc/chain_head: Check storage keys for prefixes

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* chain_head/tests: Check storage queries with invalid prefixes

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* rpc/chain_head: Allow maximum number of pinned blocks

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* chain_head/tests: Test the maximum number of pinned blocks

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* rpc/chain_head: Adjust to origin/master and apply clippy

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* client/service: Enable the `chainHead` API

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* rpc/chain_head: Stop subscription on client disconnect and add debug logs

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* rpc/chain_head: Fix sending `Stop` on subscription exit

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* rpc/chain_head: Check best block is descendent of latest finalized

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* chain_head/tests: Report events before pruning the best block

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* rpc/chain_head: Nonrecursive initial block generation

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* rpc/chain_head: Generate initial events on subscription executor

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* rpc/chain_head: Reduce dev-dependencies for tokio

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* Apply suggestions from code review

Co-authored-by: Sebastian Kunert <skunert49@gmail.com>

* rpc/chain_head: Accept empty parameters

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* rpc/chain_head: Use debug of `HexDisplay` for full format

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* rpc/chain_head: Enable subscription ID

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* rpc/chain_head: Use jsonrpsee 16.2 camelCase feature for paramaters

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* rpc/chain_head: Use `NonZeroUsize` for `NetworkConfig` param

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* rpc/chain_head: Rename `runtime_updates` to `has_runtime_updates`

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>
Co-authored-by: Sebastian Kunert <skunert49@gmail.com>

substrate/client/service/src/builder.rs

@@ -59,7 +59,7 @@ use sc_rpc::{
 	system::SystemApiServer,
 	DenyUnsafe, SubscriptionTaskExecutor,
 };
-use sc_rpc_spec_v2::transaction::TransactionApiServer;
+use sc_rpc_spec_v2::{chain_head::ChainHeadApiServer, transaction::TransactionApiServer};
 use sc_telemetry::{telemetry, ConnectionMessage, Telemetry, TelemetryHandle, SUBSTRATE_INFO};
 use sc_transaction_pool_api::MaintainedTransactionPool;
 use sc_utils::mpsc::{tracing_unbounded, TracingUnboundedSender};
@@ -549,7 +549,7 @@ where
 			keystore.clone(),
 			system_rpc_tx.clone(),
 			&config,
-			backend.offchain_storage(),
+			backend.clone(),
 			&*rpc_builder,
 		)
 	};
@@ -643,7 +643,7 @@ fn gen_rpc_module<TBl, TBackend, TCl, TRpc, TExPool>(
 	keystore: SyncCryptoStorePtr,
 	system_rpc_tx: TracingUnboundedSender<sc_rpc::system::Request<TBl>>,
 	config: &Configuration,
-	offchain_storage: Option<<TBackend as sc_client_api::backend::Backend<TBl>>::OffchainStorage>,
+	backend: Arc<TBackend>,
 	rpc_builder: &(dyn Fn(DenyUnsafe, SubscriptionTaskExecutor) -> Result<RpcModule<TRpc>, Error>),
 ) -> Result<RpcModule<()>, Error>
 where
@@ -698,6 +698,19 @@ where
 	)
 	.into_rpc();
 
+	// Maximum pinned blocks per connection.
+	// This number is large enough to consider immediate blocks,
+	// but it will change to facilitate adequate limits for the pinning API.
+	const MAX_PINNED_BLOCKS: usize = 4096;
+	let chain_head_v2 = sc_rpc_spec_v2::chain_head::ChainHead::new(
+		client.clone(),
+		backend.clone(),
+		task_executor.clone(),
+		client.info().genesis_hash,
+		MAX_PINNED_BLOCKS,
+	)
+	.into_rpc();
+
 	let author = sc_rpc::author::Author::new(
 		client.clone(),
 		transaction_pool,
@@ -709,7 +722,7 @@ where
 
 	let system = sc_rpc::system::System::new(system_info, system_rpc_tx, deny_unsafe).into_rpc();
 
-	if let Some(storage) = offchain_storage {
+	if let Some(storage) = backend.offchain_storage() {
 		let offchain = sc_rpc::offchain::Offchain::new(storage, deny_unsafe).into_rpc();
 
 		rpc_api.merge(offchain).map_err(|e| Error::Application(e.into()))?;
@@ -717,6 +730,7 @@ where
 
 	// Part of the RPC v2 spec.
 	rpc_api.merge(transaction_v2).map_err(|e| Error::Application(e.into()))?;
+	rpc_api.merge(chain_head_v2).map_err(|e| Error::Application(e.into()))?;
 
 	// Part of the old RPC spec.
 	rpc_api.merge(chain).map_err(|e| Error::Application(e.into()))?;