fix: download matched blocks even previous download are not finished

[chaoticlonghair]

Issue

If the matched blocks in memory are not empty, but the matched blocks in storage are not empty, the download process will hang.

This logic is existed since 2022 without changes.

ckb-light-client/src/protocols/filter/block_filter.rs

Lines 200 to 228 in 09b9ae5

	if let Some((db_start_number, blocks_count, db_blocks)) =
	self.storage.get_earliest_matched_blocks()
	{
	if matched_blocks.is_empty() {
	debug!(
	"recover matched blocks from storage, start_number={}, blocks_count={}, matched_count: {}",
	db_start_number, blocks_count,
	matched_blocks.len(),
	);
	// recover matched blocks from storage
	self.peers
	.add_matched_blocks(&mut matched_blocks, db_blocks);
	let tip_header = self.storage.get_tip_header();
	prove_or_download_matched_blocks(
	Arc::clone(&self.peers),
	&tip_header,
	&matched_blocks,
	nc.as_ref(),
	INIT_BLOCKS_IN_TRANSIT_PER_PEER,
	);
	if prove_state_number >= start_number {
	debug!(
	"send get block filters to {}, start_number={}",
	peer, start_number
	);
	self.send_get_block_filters(Arc::clone(&nc), *peer, start_number);
	}
	}
	} else if self.should_ask() && prove_state_number >= start_number {

Ref: #77

Solution

After reading the code, in my understanding:

• When a set of new possible matched blocks is found, it will be added into storage.
• If the set of matched blocks in memory is empty, load the earliest set of possible matched blocks from storage.
• If all matched blocks in memory are downloaded, then clear the memory.

So, prove_or_download_matched_blocks(..) should be executed when memory are not empty.

[chaoticlonghair]

After I pushed this PR, I notice that: with get_idle_blocks(..), it should not be stuck.

ckb-light-client/src/protocols/light_client/mod.rs

Lines 143 to 145 in 51d2895

	constant::GET_IDLE_BLOCKS_TOKEN => {
	self.get_idle_blocks(nc.as_ref());
	}

ckb-light-client/src/protocols/light_client/mod.rs

Lines 694 to 704 in 51d2895

	fn get_idle_blocks(&mut self, nc: &dyn CKBProtocolContext) {
	let tip_header = self.storage.get_tip_header();
	let matched_blocks = self.peers.matched_blocks().read().expect("poisoned");
	prove_or_download_matched_blocks(
	Arc::clone(&self.peers),
	&tip_header,
	&matched_blocks,
	nc,
	self.init_blocks_in_transit_per_peer(),
	);
	}