archive: Refactor archive_storage method into subscription

prdoc/pr_5997.prdoc

@@ -0,0 +1,18 @@
+# Schema: Polkadot SDK PRDoc Schema (prdoc) v1.0.0
+# See doc at https://raw.githubusercontent.com/paritytech/polkadot-sdk/master/prdoc/schema_user.json
+
+title: Implement archive_unstable_storageDiff method
+
+doc:
+  - audience: Node Dev
+    description: |
+      This PR implements the `archive_unstable_storageDiff` rpc-v2 method.
+      Developers can use this method to fetch the storage differences
+      between two blocks. This is useful for oracles and archive nodes.
+      For more details see: https://github.com/paritytech/json-rpc-interface-spec/blob/main/src/api/archive_unstable_storageDiff.md.
+
+crates:
+  - name: sc-rpc-spec-v2
+    bump: major
+  - name: sc-service
+    bump: patch

substrate/client/rpc-spec-v2/Cargo.toml

@@ -42,6 +42,7 @@ log = { workspace = true, default-features = true }
 futures-util = { workspace = true }
 rand = { workspace = true, default-features = true }
 schnellru = { workspace = true }
+itertools = { workspace = true }
 
 [dev-dependencies]
 async-trait = { workspace = true }

substrate/client/rpc-spec-v2/src/archive/api.rs

@@ -19,7 +19,9 @@
 //! API trait of the archive methods.
 
 use crate::{
-	common::events::{ArchiveStorageResult, PaginatedStorageQuery},
+	common::events::{
+		ArchiveStorageDiffEvent, ArchiveStorageDiffItem, ArchiveStorageEvent, StorageQuery,
+	},
 	MethodResult,
 };
 use jsonrpsee::{core::RpcResult, proc_macros::rpc};
@@ -97,11 +99,32 @@ pub trait ArchiveApi<Hash> {
 	/// # Unstable
 	///
 	/// This method is unstable and subject to change in the future.
-	#[method(name = "archive_unstable_storage", blocking)]
+	#[subscription(
+		name = "archive_unstable_storage" => "archive_unstable_storageEvent",
+		unsubscribe = "archive_unstable_stopStorage",
+		item = ArchiveStorageEvent,
+	)]
 	fn archive_unstable_storage(
 		&self,
 		hash: Hash,
-		items: Vec<PaginatedStorageQuery<String>>,
+		items: Vec<StorageQuery<String>>,
 		child_trie: Option<String>,
-	) -> RpcResult<ArchiveStorageResult>;
+	);
+
+	/// Returns the storage difference between two blocks.
+	///
+	/// # Unstable
+	///
+	/// This method is unstable and can change in minor or patch releases.
+	#[subscription(
+		name = "archive_unstable_storageDiff" => "archive_unstable_storageDiffEvent",
+		unsubscribe = "archive_unstable_storageDiff_stopStorageDiff",
+		item = ArchiveStorageDiffEvent,
+	)]
+	fn archive_unstable_storage_diff(
+		&self,
+		hash: Hash,
+		items: Vec<ArchiveStorageDiffItem<String>>,
+		previous_hash: Option<Hash>,
+	);
 }