Fix: block_filter: refresh_snapshot() in build_filter_data may race with ChainService

[eval-exec]

What problem does this PR solve?

Problem Summary:

block-filter::build_filter_data call refresh_snapshot on every new_block_watcher.changed() here:

ckb/block-filter/src/filter.rs

Line 94 in d3fc58f

self.shared.refresh_snapshot();

and ChainService may update snapshot simultaneously in here:

ckb/chain/src/chain.rs

Lines 480 to 486 in d3fc58f

	let new_snapshot =
	self.shared
	.new_snapshot(tip_header, total_difficulty, epoch, new_proposals);
	self.shared.store_snapshot(Arc::clone(&new_snapshot));

For example:

1. In fn build_filter_data, refresh_snapshot load a Snapshot with tip_header(100)
2. ChainService received a new_tip_header(101), and store it into snapshot
3. In fn build_filter_data, refresh_snapshot store the Snapshot with tip_header(100), this cause tip_header goes backwards.

What's Changed:

remove refresh_snapshot() in block-filter::build_filter_data

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
• No code ci-runs-only: [ quick_checks,linters ]

Release note

None: Exclude this PR from the release note.

[eval-exec]

The CI job was failed after I removed refresh_snapshot() in block-filter::build_filter_data.

When a new tip block comes, ChainService will get a new RocksDB's StoreSnapshot and store it to snapshot after commit the new tip block into RocksDB. Then block-filter get notified and build filter data for the new tip block.

In build_filter_data_for_block, it just only commit the block filter data into rocksdb via StoreTransaction, but the snapshot's inner value(RocksDBSnapshot) doesn't contains the new tip block's block filter data.

ckb/block-filter/src/filter.rs

Lines 144 to 149 in 2ad82e6

	let filter_data = filter_writer.into_inner();
	let db_transaction = db.begin_transaction();
	db_transaction
	.insert_block_filter(&header.hash(), &filter_data.pack())
	.expect("insert_block_filter should be ok");
	db_transaction.commit().expect("commit should be ok");

but in ChainRpc::get_block_filter, it will load a snapshot which doesn't contains the new tip blocks' block filter data, since I removed refresh_snapshot() from block-filter::build_filter_data. So the CI job failed.

ckb/rpc/src/module/chain.rs

Lines 1646 to 1653 in cd1e2f8

	fn get_block_filter(&self, block_hash: H256) -> Result<Option<JsonBytes>> {
	let snapshot = self.shared.snapshot();
	let block_hash = block_hash.pack();
	if !snapshot.is_main_chain(&block_hash) {
	return Ok(None);
	}
	Ok(snapshot.get_block_filter(&block_hash).map(Into::into))
	}

[quake]

bors r=quake,driftluo

[bors]

Build succeeded:

• ci_benchmarks_ubuntu
• ci_cargo_deny_ubuntu
• ci_integration_tests_ubuntu
• ci_linters_ubuntu
• ci_quick_checks_ubuntu
• ci_unit_tests_ubuntu
• ci_wasm_build_ubuntu