light-client: Add experimental light-client support (#965)

* rpc/types: Decode `SubstrateTxStatus` for substrate and smoldot

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

* lightclient: Add light client Error

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

* lightclient: Add background task to manage RPC responses

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

* lightclient: Implement the light client RPC in subxt

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

* subxt: Expose light client under experimental feature-flag

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

* artifacts: Add development chain spec for local nodes

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

* Update cargo lock

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

* examples: Add light client example

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

* Update sp-* crates and smoldot to use git with branch / rev

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

* Apply cargo fmt

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

* Fix clippy

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

* Import hashmap entry

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

* lightclient: Fetch spec only if jsonrpsee feature is enabled

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

* Update subxt/src/rpc/lightclient/background.rs

Co-authored-by: Niklas Adolfsson <niklasadolfsson1@gmail.com>

* Fix typo

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

* artifacts: Update dev chain spec

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

* types: Handle storage replies from chainHead_storage

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

* artifacts: Add polkadot spec

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

* lightclient: Handle RPC error responses

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

* examples: Tx basic with light client for local nodes

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

* example: Light client coprehensive example for live chains

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

* examples: Remove prior light client example

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

* feature: Rename experimental to unstable

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

* book: Add light client section

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

* testing: Fix clippy

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

* lightclient: Ignore validated events

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

* Adjust tests for light-clients and normal clients

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

* testing: Keep lightclient variant

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

* Remove support for chainHead_storage for light client

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

* Update light client to point to crates.io

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

* Update sp-crates from crates.io

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

* Replace Atomic with u64

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

* Add LightClientBuilder

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

* Adjust chainspec with provided bootnodes

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

* Add potential_relay_chains to light client builder

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

* Move the light-client to the background task

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

* Adjust tracing logs

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

* Update book and example

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

* Apply cargo fmt

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

* Remove dev_spec.json artifact

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

* Examples fix duplicate Cargo.toml

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

* Use tracing_subscriber crate

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

* Fix clippy for different features

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

* Add comment about bootNodes

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

* Add comment about tracing-sub dependency

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

* Run integration-tests with light-client

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

* Feature guard some incompatible tests

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

* ci: Enable light-client tests under feature flag

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

* ci: Fix git step name

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

* Adjust flags for testing

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

* Adjust warnings

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

* Rename feature flag jsonrpsee-ws to jsonrpsee

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

* Fix cargo check

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

* ci: Run tests on just 2 threads

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

* Move light-client to subxt/src/client

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

* Adjust LightClientBuilder

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

* Use ws_url to construct light client for testing

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

* Refactor background

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

* Address feedback

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

* Remove polkadot.spec and trim sub_id

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

* Wait for substrate to produce block before connecting light client

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

* Adjust builder and tests

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

* Apply fmt

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

* ci: Use release for light client testing

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

* Add single test for light-client

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

* Wait for more blocks

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

* Use polkadot endpoint for testing

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

* Adjust cargo check

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

* examples: Remove light client chain connection example

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

* Adjust cargo.toml section for the old example

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

* Adjust background task to use usize for subscription Id

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

* Build bootnodes with serde_json::Value directly

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

* Make channel between subxt user and subxt background unbounded

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

* Update subxt/src/client/lightclient/builder.rs

Co-authored-by: Niklas Adolfsson <niklasadolfsson1@gmail.com>

* Switch to smoldot 0.6.0 from 0.5.0

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

* Move testing to `full_client` and `light_client` higher modules

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

* Remove subscriptionID type

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

* Remove subxt/integration-testing feature flag

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

* Adjust wait_for_blocks documentation

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

* Adjust utils import for testing

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

* Remove into_iter from builder construction

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

---------

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>
Co-authored-by: Niklas Adolfsson <niklasadolfsson1@gmail.com>

subxt/Cargo.toml

@@ -53,10 +53,15 @@ substrate-compat = [
 # latest features exposed by the metadata.
 unstable-metadata = []
 
-# Enable this to expose functionality only used for integration testing.
-# The exposed functionality is subject to breaking changes at any point,
-# and should not be relied upon.
-integration-tests = []
+# Activate this to expose the Light Client functionality.
+# Note that this feature is experimental and things may break or not work as expected.
+unstable-light-client = [
+    "smoldot-light/std",
+    "tokio-stream",
+    "tokio/sync",
+    "tokio/rt",
+    "futures-util",
+]
 
 [dependencies]
 codec = { package = "parity-scale-codec", workspace = true, features = ["derive"] }
@@ -95,6 +100,12 @@ sp-runtime = { workspace = true, optional = true }
 subxt-macro = { workspace = true }
 subxt-metadata = { workspace = true }
 
+# Light client support:
+smoldot-light = { workspace = true, optional = true }
+tokio = { workspace = true, optional = true }
+tokio-stream = { workspace = true, optional = true }
+futures-util = { workspace = true, optional = true }
+
 # Included if "web" feature is enabled, to enable its js feature.
 getrandom = { workspace = true, optional = true }
 
@@ -108,4 +119,19 @@ sp-runtime = { workspace = true }
 sp-keyring = { workspace = true }
 sp-version = { workspace = true }
 assert_matches = { workspace = true }
-subxt-signer = { workspace = true, features = ["subxt"] }
+subxt-signer = { workspace = true, features = ["subxt"] }
+# Tracing subscriber is useful for light-client examples to ensure that
+# the `bootNodes` and chain spec are configured correctly. If all is fine, then
+# the light-client wlll emit INFO logs with
+# `GrandPa warp sync finished` and `Finalized block runtime ready.`
+tracing-subscriber = { workspace = true }
+
+[[example]]
+name = "unstable_light_client_tx_basic"
+path = "examples/unstable_light_client_tx_basic.rs"
+required-features = ["unstable-light-client", "jsonrpsee"]
+
+[profile.dev.package.smoldot-light]
+opt-level = 2
+[profile.test.package.smoldot-light]
+opt-level = 2