Adapt parser for Bitcoin Core's block storage XOR

[shesek]

bitcoin/bitcoin#28052

[maflcko]

Just for clarity: The XOR pattern is only applied when the blocksdir is freshly created, and there is also an option to disable it (on creation).

So an alternative to adapt the parser would be to require the option to be disabled, for now. (Possibly for esplora a config update similar to commit Blockstream/esplora@52c1ecd could work)

[junderw]

mempool/electrs#101

I added support that basically doesn't look at any config, but rather uses the presence of the xor.dat file to decide whether to use it.

[junderw]

Blockstream:

electrs/src/new_index/fetch.rs

Lines 153 to 170 in 306f66a

	fn blkfiles_reader(blk_files: Vec<PathBuf>) -> Fetcher<Vec<u8>> {
	let chan = SyncChannel::new(1);
	let sender = chan.sender();
	Fetcher::from(
	chan.into_receiver(),
	spawn_thread("blkfiles_reader", move || {
	for path in blk_files {
	trace!("reading {:?}", path);
	let blob = fs::read(&path)
	.unwrap_or_else(|e| panic!("failed to read {:?}: {:?}", path, e));
	sender
	.send(blob)
	.unwrap_or_else(|_| panic!("failed to send {:?} contents", path));
	}
	}),
	)
	}

mempool:

https://github.com/mempool/electrs/blob/10274b50ec4b8828c1d33aea0b3f87c86fb9f90e/src/new_index/fetch.rs#L149-L185

Looks like that portion is untouched so you could just merge that in if you want.

[junderw]

We plan to release it as a patch v3.0.1 once Core releases v28

[shesek]

Resolved by #130.