xxx: Backup

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

Cargo.lock

@@ -4284,6 +4284,8 @@ dependencies = [
  "sp-keyring",
  "subxt",
  "tokio",
+ "tracing",
+ "tracing-subscriber 0.3.17",
 ]
 
 [[package]]

examples/Cargo.toml

@@ -18,3 +18,5 @@ tokio = { workspace = true }
 futures = { workspace = true }
 hex = { workspace = true }
 sp-keyring = { workspace = true }
+tracing = { workspace = true }
+tracing-subscriber = { workspace = true }

examples/examples/storage_iterating.rs

@@ -12,7 +12,7 @@ async fn main() -> Result<(), Box<dyn std::error::Error>> {
     let storage_query = polkadot::storage().system().account_root();
 
     // Get back an iterator of results (here, we are fetching 10 items at
-    // a time from the node, but we always iterate over oen at a time).
+    // a time from the node, but we always iterate over one at a time).
     let mut results = api
         .storage()
         .at_latest()

examples/examples/tx_basic_light_client.rs

@@ -1,8 +1,27 @@
-use sp_keyring::AccountKeyring;
-use subxt::rpc::LightClient;
-use subxt::{tx::PairSigner, OnlineClient, PolkadotConfig};
+//! This is a comprehensive example that utilizes the Light Client
+//! for all subxt requests.
+//!
+//! Includes:
+//!  - submitting a transaction to a local development chain
+//!  - Subscribes to all finalized blocks using the old RPC method
+//!  - Subscribes to the head of the chain using the new `chainHead` RPC method
+//!  - Dynamically query constants
+//!  - Dynamically decode the events of the latest block
+//!  - Various RPC calls to ensure proper shape of the response.
+//!
+//! # Note
+//!
+//! This feature is experimental and things might break without notice.
 
+use futures::StreamExt;
+use sp_keyring::AccountKeyring;
 use std::sync::Arc;
+use subxt::dynamic::At;
+use subxt::dynamic::Value;
+use subxt::rpc::types::FollowEvent;
+use subxt::rpc::LightClient;
+use subxt::utils::AccountId32;
+use subxt::{OnlineClient, PolkadotConfig};
 
 // Generate an interface that we can use from the node's metadata.
 #[subxt::subxt(runtime_metadata_path = "../artifacts/polkadot_metadata_small.scale")]
@@ -10,28 +29,188 @@ pub mod polkadot {}
 
 #[tokio::main]
 async fn main() -> Result<(), Box<dyn std::error::Error>> {
+    tracing_subscriber::fmt::init();
+
+    println!("Creating light client");
     // Create a light client from the provided chain spec.
     let light_client = LightClient::new(include_str!("../../artifacts/dev_spec.json"))?;
     let api = OnlineClient::<PolkadotConfig>::from_rpc_client(Arc::new(light_client)).await?;
+    println!("Done with creating light client");
 
     // Build a balance transfer extrinsic.
-    let dest = AccountKeyring::Bob.to_account_id().into();
-    let balance_transfer_tx = polkadot::tx().balances().transfer(dest, 10_000);
+    // {
+    //     let dest = AccountKeyring::Bob.to_account_id().into();
+    //     let balance_transfer_tx = polkadot::tx().balances().transfer(dest, 10_000);
 
-    // Submit the balance transfer extrinsic from Alice, and wait for it to be successful
-    // and in a finalized block. We get back the extrinsic events if all is well.
-    let from = PairSigner::new(AccountKeyring::Alice.pair());
-    let events = api
-        .tx()
-        .sign_and_submit_then_watch_default(&balance_transfer_tx, &from)
-        .await?
-        .wait_for_finalized_success()
-        .await?;
+    //     // Submit the balance transfer extrinsic from Alice, and wait for it to be successful
+    //     // and in a finalized block. We get back the extrinsic events if all is well.
+    //     let from = PairSigner::new(AccountKeyring::Alice.pair());
+    //     let events = api
+    //         .tx()
+    //         .sign_and_submit_then_watch_default(&balance_transfer_tx, &from)
+    //         .await?
+    //         .wait_for_finalized_success()
+    //         .await?;
 
-    // Find a Transfer event and print it.
-    let transfer_event = events.find_first::<polkadot::balances::events::Transfer>()?;
-    if let Some(event) = transfer_event {
-        println!("Balance transfer success: {event:?}");
+    //     // Find a Transfer event and print it.
+    //     let transfer_event = events.find_first::<polkadot::balances::events::Transfer>()?;
+    //     if let Some(event) = transfer_event {
+    //         println!("Balance transfer success: {event:?}");
+    //     }
+    // }
+
+    // Subscribe to the latest 3 finalized blocks.
+    {
+        let mut blocks_sub = api.blocks().subscribe_finalized().await?.take(3);
+        // For each block, print a bunch of information about it:
+        while let Some(block) = blocks_sub.next().await {
+            let block = block?;
+
+            let block_number = block.header().number;
+            let block_hash = block.hash();
+
+            println!("Block #{block_number}:");
+            println!("  Hash: {block_hash}");
+        }
+    }
+
+    // Subscribe to a few events from the head of the chain.
+    {
+        let blocks = api.rpc().chainhead_unstable_follow(false).await?;
+        let sub_id = blocks
+            .subscription_id()
+            .expect("RPC provides a valid subscription id; qed")
+            .to_owned();
+
+        let mut blocks = blocks.take(10);
+        while let Some(event) = blocks.next().await {
+            let event = event?;
+
+            println!("chainHead_follow event: {event:?}");
+
+            // Fetch the body, header and storage of the best blocks only.
+            let FollowEvent::BestBlockChanged(best_block) = event else {
+                continue
+            };
+            let hash = best_block.best_block_hash;
+
+            // Subscribe to fetch the block's body.
+            let mut sub = api
+                .rpc()
+                .chainhead_unstable_body(sub_id.clone(), hash)
+                .await?
+                .take(5);
+
+            while let Some(event) = sub.next().await {
+                let event = event?;
+
+                println!("  chainHead_body event: {event:?}");
+            }
+
+            // Fetch the block's header.
+            // let header = api
+            //     .rpc()
+            //     .chainhead_unstable_header(sub_id.clone(), hash)
+            //     .await?;
+            // let header = header.expect("RPC must have this header in memory; qed");
+
+            // println!("  chainHead_header: {header}");
+
+            // Make a storage query.
+            let account_id: AccountId32 = AccountKeyring::Alice.to_account_id().into();
+            let addr = polkadot::storage().system().account(account_id);
+            let addr_bytes = api.storage().address_bytes(&addr).unwrap();
+
+            let mut sub = api
+                .rpc()
+                .chainhead_unstable_storage(sub_id.clone(), hash, &addr_bytes, None)
+                .await?
+                .take(5);
+
+            while let Some(event) = sub.next().await {
+                let event = event?;
+
+                println!("  chainHead_storage event: {event:?}");
+            }
+        }
+    }
+
+    // A dynamic query to obtain some contant:
+    {
+        let constant_query = subxt::dynamic::constant("System", "BlockLength");
+
+        // Obtain the value:
+        let value = api.constants().at(&constant_query)?;
+
+        println!("Constant bytes: {:?}", value.encoded());
+        println!("Constant value: {}", value.to_value()?);
+    }
+
+    // Get events for the latest block:
+    {
+        let events = api.events().at_latest().await?;
+
+        // We can dynamically decode events:
+        println!("Dynamic event details:");
+        for event in events.iter() {
+            let event = event?;
+
+            let pallet = event.pallet_name();
+            let variant = event.variant_name();
+            let field_values = event.field_values()?;
+
+            println!("{pallet}::{variant}: {field_values}");
+        }
+    }
+
+    // Create a dynamically runtime API payload that calls the
+    // `AccountNonceApi_account_nonce` function.
+    {
+        let account = AccountKeyring::Alice.to_account_id();
+        let runtime_api_call = subxt::dynamic::runtime_api_call(
+            "AccountNonceApi_account_nonce",
+            vec![Value::from_bytes(account)],
+        );
+
+        // Submit the call to get back a result.
+        let nonce = api
+            .runtime_api()
+            .at_latest()
+            .await?
+            .call(runtime_api_call)
+            .await?;
+
+        println!("Account nonce: {:#?}", nonce.to_value());
+    }
+
+    // Build a dynamic storage query to access account information.
+    {
+        let account = AccountKeyring::Alice.to_account_id();
+        let storage_query =
+            subxt::dynamic::storage("System", "Account", vec![Value::from_bytes(account)]);
+
+        // Use that query to `fetch` a result. Because the query is dynamic, we don't know what the result
+        // type will be either, and so we get a type back that can be decoded into a dynamic Value type.
+        let result = api
+            .storage()
+            .at_latest()
+            .await?
+            .fetch(&storage_query)
+            .await?;
+        let value = result.unwrap().to_value()?;
+
+        println!("Alice has free balance: {:?}", value.at("data").at("free"));
+    }
+
+    {
+        let system_chain = api.rpc().system_chain().await?;
+        println!("System chain: {system_chain}");
+
+        let system_name = api.rpc().system_name().await?;
+        println!("System name: {system_name}");
+
+        let finalized_hash = api.rpc().finalized_head().await?;
+        println!("Finalized hash {finalized_hash:?}");
     }
 
     Ok(())

subxt/src/rpc/lightclient/background.rs

@@ -113,6 +113,8 @@ impl BackgroundTask {
                 }
             }
             Ok(RpcResponse::Subscription { method, id, result }) => {
+                println!(" BACKRGOUND response {result:?}\n");
+
                 // Subxt calls into `author_submitAndWatchExtrinsic`, however the smoldot produces
                 // `{"event":"broadcasted","numPeers":1}` which is part of the RPC V2 API. Ignore
                 // this spurious event.
@@ -131,6 +133,9 @@ impl BackgroundTask {
                             "Cannot send notification to subscription {:?}",
                             id
                         );
+
+                        // Remove the sender if the subscription dropped the receiver.
+                        self.subscriptions.remove(&id);
                     }
                     return;
                 }

subxt/src/rpc/types.rs

@@ -509,7 +509,11 @@ pub enum FollowEvent<Hash> {
 #[serde(rename_all = "camelCase")]
 pub struct ChainHeadResult<T> {
     /// Result of the method.
+    #[cfg(not(feature = "experimental-light-client"))]
     pub result: T,
+    /// Result of the method.
+    #[cfg(feature = "experimental-light-client")]
+    pub value: Vec<T>,
 }
 
 /// The event generated by the body / call / storage methods.