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fix: find common header between the header chain and the current body chain (#3033)

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* fix: find common header between the header chain and the current body chain

* add some code comments
This commit is contained in:
Gary Yu 2019-09-10 07:54:42 +08:00 committed by GitHub
parent 383985292c
commit fa0fed9de5
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GPG key ID: 4AEE18F83AFDEB23
1 changed files with 31 additions and 19 deletions
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50
chain/src/chain.rs
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@ -791,11 +791,12 @@ impl Chain {
let mut oldest_height = 0;
let mut oldest_hash = ZERO_HASH;
let mut current = self.get_block_header(&header_head.last_block_h);
// Start with body_head (head of the full block chain)
let mut current = self.get_block_header(&body_head.last_block_h);
if current.is_err() {
error!(
"{}: header_head not found in chain db: {} at {}",
caller, header_head.last_block_h, header_head.height,
"{}: body_head not found in chain db: {} at {}",
caller, body_head.last_block_h, body_head.height,
);
return Ok(false);
}
@ -804,37 +805,48 @@ impl Chain {
// TODO - Investigate finding the "common header" by comparing header_mmr and
// sync_mmr (bytes will be identical up to the common header).
//
// Traverse back through the full block chain from body head until we find a header
// that "is on current chain", which is the "fork point" between existing header chain
// and full block chain.
while let Ok(header) = current {
// break out of the while loop when we find a header common
// between the header chain and the current body chain
if header.height <= body_head.height {
if let Ok(_) = self.is_on_current_chain(&header) {
break;
}
if let Ok(_) = self.is_on_current_chain(&header) {
oldest_height = header.height;
oldest_hash = header.hash();
break;
}
oldest_height = header.height;
oldest_hash = header.hash();
if let Some(hs) = hashes {
hs.push(oldest_hash);
}
current = self.get_previous_header(&header);
}
// Traverse back through the header chain from header_head back to this fork point.
// These are the blocks that we need to request in body sync (we have the header but not the full block).
if let Some(hs) = hashes {
let mut h = self.get_block_header(&header_head.last_block_h);
while let Ok(header) = h {
if header.height <= oldest_height {
break;
}
hs.push(header.hash());
h = self.get_previous_header(&header);
}
}
if oldest_height < header_head.height.saturating_sub(horizon) {
if oldest_height > 0 {
if oldest_hash != ZERO_HASH {
// this is the normal case. for example:
// body head height is 1 (and not a fork), oldest_height will be 2
// body head height is 0 (a typical fresh node), oldest_height will be 1
// body head height is 10,001 (but at a fork), oldest_height will be 10,001
// body head height is 10,005 (but at a fork with depth 5), oldest_height will be 10,001
// body head height is 1 (and not a fork), oldest_height will be 1
// body head height is 0 (a typical fresh node), oldest_height will be 0
// body head height is 10,001 (but at a fork with depth 1), oldest_height will be 10,000
// body head height is 10,005 (but at a fork with depth 5), oldest_height will be 10,000
debug!(
"{}: need a state sync for txhashset. oldest block which is not on local chain: {} at {}",
caller, oldest_hash, oldest_height,
);
} else {
// this is the abnormal case, when is_on_current_chain() already return Err, and even for genesis block.
error!("{}: corrupted storage? oldest_height is 0 when check_txhashset_needed. state sync is needed", caller);
// this is the abnormal case, when is_on_current_chain() always return Err, and even for genesis block.
error!("{}: corrupted storage? state sync is needed", caller);
}
Ok(true)
} else {