lightclient: Add support for multi-chain usecase (#1238)

* lightclient: Make `smoldot::chainID` part of the RPC requests Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * lightclient: Make `BackgroundTask` generic over `PlatformRef` and chain Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * lightclient: Construct from raw smoldot and target different chains Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * testing: Update cargo lock for wasm tests Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * lightclient: Reuse `new_from_client` method and removed unused imports Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * lightclient: Reexport smoldot client and RPC objects used in pub interface Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * lightclient: Adjust `new_from_client` interface Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * lightclient: Extend background to poll over multiple RPC objects Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * subxt: Build light client from raw and target different chains Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * artifacts: Add demo chain specs Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * artifacts: Move artifacts to dedicated folder Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * lightclient: Use SelectAll to drive all streams Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * lightclient: Fetch initial data from the target chain Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * lightclient: Reexport other smoldot objects Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * subxt: Target chain with potentially different config Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * subxt/rpc: Log chainID for debugging Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * subxt/examples: Add smoldot client with parachain example Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * lightclient: Propagate chain ID together with rpc responses object Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * lightclient: Multiplex responses by request ID and chain ID Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * subxt: Add raw light client builder Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * subxt: Add cargo feature flag for parachains example Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * lightclient: Derive default for internal structure Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * lightclient: Guard reexports by std feature flag Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * Update subxt/src/client/light_client/mod.rs Co-authored-by: James Wilson <james@jsdw.me> * lightclient: Update the builder pattern and chain targetting Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * lightclient: Fix documentation Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * Provide more insightful docs wrt native/wasm panics Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * examples: Adjust comment location Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * lightclient: Refactor UniqueChainId into the background task Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * Update lightclient/src/background.rs Co-authored-by: Niklas Adolfsson <niklasadolfsson1@gmail.com> * Update subxt/src/client/light_client/builder.rs Co-authored-by: James Wilson <james@jsdw.me> * lightclient: Update docs wrt panics Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * subxt: Update docs wrt to smoldot instance -> client Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * lightclient: Use IntoIter instead of Iterator Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * subxt: Adjsut docs wrt [`Self::new_from_client`] Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * subxt: Remove RawRpc from LightClient in favor of chainID Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * lightclient: Reexport everything under smoldot module Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * artifacts: Use stateRootHash instead of genesis.raw Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> --------- Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> Co-authored-by: James Wilson <james@jsdw.me> Co-authored-by: Niklas Adolfsson <niklasadolfsson1@gmail.com>
2026-06-11 17:41:08 +00:00 · 2023-11-16 18:29:00 +02:00
parent 7b210f5a8e
commit 34ff3da37d
11 changed files with 606 additions and 104 deletions
@@ -0,0 +1,101 @@
+use futures::StreamExt;
+use std::{iter, num::NonZeroU32};
+use subxt::{
+    client::{LightClient, RawLightClient},
+    PolkadotConfig,
+};
+
+// Generate an interface that we can use from the node's metadata.
+#[subxt::subxt(runtime_metadata_path = "../artifacts/polkadot_metadata_small.scale")]
+pub mod polkadot {}
+
+const POLKADOT_SPEC: &str = include_str!("../../artifacts/demo_chain_specs/polkadot.json");
+const ASSET_HUB_SPEC: &str =
+    include_str!("../../artifacts/demo_chain_specs/polkadot_asset_hub.json");
+
+#[tokio::main]
+async fn main() -> Result<(), Box<dyn std::error::Error>> {
+    // The smoldot logs are informative:
+    tracing_subscriber::fmt::init();
+
+    // Connecting to a parachain is a multi step process.
+
+    // Step 1. Construct a new smoldot client.
+    let mut client =
+        subxt_lightclient::smoldot::Client::new(subxt_lightclient::smoldot::DefaultPlatform::new(
+            "subxt-example-light-client".into(),
+            "version-0".into(),
+        ));
+
+    // Step 2. Connect to the relay chain of the parachain. For this example, the Polkadot relay chain.
+    let polkadot_connection = client
+        .add_chain(subxt_lightclient::smoldot::AddChainConfig {
+            specification: POLKADOT_SPEC,
+            json_rpc: subxt_lightclient::smoldot::AddChainConfigJsonRpc::Enabled {
+                max_pending_requests: NonZeroU32::new(128).unwrap(),
+                max_subscriptions: 1024,
+            },
+            potential_relay_chains: iter::empty(),
+            database_content: "",
+            user_data: (),
+        })
+        .expect("Light client chain added with valid spec; qed");
+    let polkadot_json_rpc_responses = polkadot_connection
+        .json_rpc_responses
+        .expect("Light client configured with json rpc enabled; qed");
+    let polkadot_chain_id = polkadot_connection.chain_id;
+
+    // Step 3. Connect to the parachain. For this example, the Asset hub parachain.
+    let assethub_connection = client
+        .add_chain(subxt_lightclient::smoldot::AddChainConfig {
+            specification: ASSET_HUB_SPEC,
+            json_rpc: subxt_lightclient::smoldot::AddChainConfigJsonRpc::Enabled {
+                max_pending_requests: NonZeroU32::new(128).unwrap(),
+                max_subscriptions: 1024,
+            },
+            // The chain specification of the asset hub parachain mentions that the identifier
+            // of its relay chain is `polkadot`.
+            potential_relay_chains: [polkadot_chain_id].into_iter(),
+            database_content: "",
+            user_data: (),
+        })
+        .expect("Light client chain added with valid spec; qed");
+    let parachain_json_rpc_responses = assethub_connection
+        .json_rpc_responses
+        .expect("Light client configured with json rpc enabled; qed");
+    let parachain_chain_id = assethub_connection.chain_id;
+
+    // Step 4. Turn the smoldot client into a raw client.
+    let raw_light_client = RawLightClient::builder()
+        .add_chain(polkadot_chain_id, polkadot_json_rpc_responses)
+        .add_chain(parachain_chain_id, parachain_json_rpc_responses)
+        .build(client)
+        .await?;
+
+    // Step 5. Obtain a client to target the relay chain and the parachain.
+    let polkadot_api: LightClient<PolkadotConfig> =
+        raw_light_client.for_chain(polkadot_chain_id).await?;
+    let parachain_api: LightClient<PolkadotConfig> =
+        raw_light_client.for_chain(parachain_chain_id).await?;
+
+    // Step 6. Subscribe to the finalized blocks of the chains.
+    let polkadot_sub = polkadot_api
+        .blocks()
+        .subscribe_finalized()
+        .await?
+        .map(|block| ("Polkadot", block));
+    let parachain_sub = parachain_api
+        .blocks()
+        .subscribe_finalized()
+        .await?
+        .map(|block| ("AssetHub", block));
+    let mut stream_combinator = futures::stream::select(polkadot_sub, parachain_sub);
+
+    while let Some((chain, block)) = stream_combinator.next().await {
+        let block = block?;
+
+        println!("     Chain {:?} hash={:?}", chain, block.hash());
+    }
+
+    Ok(())
+}