sc-block-builder: Remove BlockBuilderProvider (#2099)

The `BlockBuilderProvider` was a trait that was defined in
`sc-block-builder`. The trait was implemented for `Client`. This
basically meant that you needed to import `sc-block-builder` any way to
have access to the block builder. So, this trait was not providing any
real value. This pull request is removing the said trait. Instead of the
trait it introduces a builder for creating a `BlockBuilder`. The builder
currently has the quite fabulous name `BlockBuilderBuilder` (I'm open to
any better name 😅). The rest of the pull request is about
replacing the old trait with the new builder.

# Downstream code changes

If you used `new_block` or `new_block_at` before you now need to switch
it over to the new `BlockBuilderBuilder` pattern:

```rust
// `new` requires a type that implements `CallApiAt`. 
let mut block_builder = BlockBuilderBuilder::new(client)
                // Then you need to specify the hash of the parent block the block will be build on top of
		.on_parent_block(at)
                // The block builder also needs the block number of the parent block. 
                // Here it is fetched from the given `client` using the `HeaderBackend`
                // However, there also exists `with_parent_block_number` for directly passing the number
		.fetch_parent_block_number(client)
		.unwrap()
                // Enable proof recording if required. This call is optional.
		.enable_proof_recording()
                // Pass the digests. This call is optional.
                .with_inherent_digests(digests)
		.build()
		.expect("Creates new block builder");
```

---------

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

substrate/bin/node/cli/benches/block_production.rs

@@ -20,7 +20,7 @@ use criterion::{criterion_group, criterion_main, BatchSize, Criterion, Throughpu
 
 use kitchensink_runtime::{constants::currency::*, BalancesCall};
 use node_cli::service::{create_extrinsic, FullClient};
-use sc_block_builder::{BlockBuilderProvider, BuiltBlock, RecordProof};
+use sc_block_builder::{BlockBuilderBuilder, BuiltBlock};
 use sc_consensus::{
 	block_import::{BlockImportParams, ForkChoiceStrategy},
 	BlockImport, StateAction,
@@ -127,7 +127,11 @@ fn prepare_benchmark(client: &FullClient) -> (usize, Vec<OpaqueExtrinsic>) {
 
 	let mut max_transfer_count = 0;
 	let mut extrinsics = Vec::new();
-	let mut block_builder = client.new_block(Default::default()).unwrap();
+	let mut block_builder = BlockBuilderBuilder::new(client)
+		.on_parent_block(client.chain_info().best_hash)
+		.with_parent_block_number(client.chain_info().best_number)
+		.build()
+		.unwrap();
 
 	// Every block needs one timestamp extrinsic.
 	let extrinsic_set_time = extrinsic_set_time(1 + MINIMUM_PERIOD_FOR_BLOCKS);
@@ -174,7 +178,11 @@ fn block_production(c: &mut Criterion) {
 
 	// Buliding the very first block is around ~30x slower than any subsequent one,
 	// so let's make sure it's built and imported before we benchmark anything.
-	let mut block_builder = client.new_block(Default::default()).unwrap();
+	let mut block_builder = BlockBuilderBuilder::new(client)
+		.on_parent_block(client.chain_info().best_hash)
+		.with_parent_block_number(client.chain_info().best_number)
+		.build()
+		.unwrap();
 	block_builder.push(extrinsic_set_time(1)).unwrap();
 	import_block(client, block_builder.build().unwrap());
 
@@ -186,14 +194,19 @@ fn block_production(c: &mut Criterion) {
 	group.sample_size(10);
 	group.throughput(Throughput::Elements(max_transfer_count as u64));
 
-	let best_hash = client.chain_info().best_hash;
+	let chain = client.chain_info();
+	let best_hash = chain.best_hash;
+	let best_number = chain.best_number;
 
 	group.bench_function(format!("{} transfers (no proof)", max_transfer_count), |b| {
 		b.iter_batched(
 			|| extrinsics.clone(),
 			|extrinsics| {
-				let mut block_builder =
-					client.new_block_at(best_hash, Default::default(), RecordProof::No).unwrap();
+				let mut block_builder = BlockBuilderBuilder::new(client)
+					.on_parent_block(best_hash)
+					.with_parent_block_number(best_number)
+					.build()
+					.unwrap();
 				for extrinsic in extrinsics {
 					block_builder.push(extrinsic).unwrap();
 				}
@@ -207,8 +220,11 @@ fn block_production(c: &mut Criterion) {
 		b.iter_batched(
 			|| extrinsics.clone(),
 			|extrinsics| {
-				let mut block_builder =
-					client.new_block_at(best_hash, Default::default(), RecordProof::Yes).unwrap();
+				let mut block_builder = BlockBuilderBuilder::new(client)
+					.on_parent_block(best_hash)
+					.with_parent_block_number(best_number)
+					.build()
+					.unwrap();
 				for extrinsic in extrinsics {
 					block_builder.push(extrinsic).unwrap();
 				}