Module sync 

The syncer downloads and verifies large numbers of blocks from peers to Zebra.

It is used when Zebra is a long way behind the current chain tip.

Modules

downloads 🔒

A download stream for Zebra’s block syncer.

end_of_support

End of support checking task.

gossip 🔒

A task that gossips newly verified block::Hashes to peers.

hedge 🔒

Preserve a live hedge arm when its sibling exhausts its retries.

progress 🔒

Progress tracking for blockchain syncing.

recent_sync_lengths 🔒

A channel which holds a list of recent syncer response lengths.

status 🔒

Syncer chain tip status, based on recent block locator responses from peers.

Structs

ChainSync

CheckedTip 🔒

Helps work around defects in the bitcoin protocol by checking whether the returned hashes actually extend a chain tip.

Config

Sync configuration section.

RecentSyncLengths

A helper type which holds a list of recent syncer response lengths. These sync lengths can be used to work out if Zebra has reached the end of the chain.

SyncStatus

A helper type to determine if the synchronizer has likely reached the chain tip.

Enums

BlockGossipError

Errors that can occur when gossiping committed blocks

Constants

BLOCK_DOWNLOAD_RETRY_LIMIT 🔒

Controls how many times we will retry each block download.

BLOCK_DOWNLOAD_ROUND_TIMEOUT 🔒

Bounds one complete block download round, including readiness, capacity waits and both hedges.

BLOCK_DOWNLOAD_TIMEOUT 🔒

The per-peer wire-response budget used to derive complete download deadlines.

BLOCK_VERIFY_TIMEOUT 🔒

Controls how long we wait for a block verify request to complete.

DEFAULT_CHECKPOINT_CONCURRENCY_LIMIT

The default for the user-specified lookahead limit.

FANOUT 🔒

Controls the number of peers used for each ObtainTips and ExtendTips request.

FINAL_CHECKPOINT_BLOCK_VERIFY_TIMEOUT 🔒

A shorter timeout used for the first few blocks after the final checkpoint.

FINAL_CHECKPOINT_BLOCK_VERIFY_TIMEOUT_LIMIT 🔒

The number of blocks after the final checkpoint that get the shorter timeout.

GENESIS_TIMEOUT_RETRY 🔒

Controls how long we wait to retry a failed attempt to download and verify the genesis block.

MAX_BLOCK_REOBTAIN_RETRIES 🔒

Controls how many times the syncer will re-request a block whose download failed because no peer delivered it (a NotFound), before giving up and letting the normal tip re-walk handle it.

MAX_TIPS_RESPONSE_HASH_COUNT

The expected maximum number of hashes in an ObtainTips or ExtendTips response.

MIN_CHECKPOINT_CONCURRENCY_LIMIT

A lower bound on the user-specified checkpoint verification concurrency limit.

MIN_CONCURRENCY_LIMIT

A lower bound on the user-specified concurrency limit.

MIN_UTXO_RACE_DROPS_BEFORE_RESTART 🔒

The fewest TransparentInputNotFound drops without a verified block before the sync restarts, so a low full_verify_concurrency_limit can’t disable the #11168 exemption.

PEER_GOSSIP_DELAY

Controls how long we wait between gossiping successive blocks or transactions.

REGTEST_SYNC_RESTART_DELAY 🔒

In regtest, use a much shorter restart delay so that downstream nodes pick up newly-mined blocks quickly (e.g. after generate(N) in integration tests). The default 67-second delay exceeds the typical sync_all timeout of 60 seconds.

SYNC_RESTART_DELAY 🔒

Controls how long we wait to restart syncing after finishing a sync run.

TIPS_RESPONSE_TIMEOUT

Controls how long we wait for a tips response to return.

VERIFICATION_PIPELINE_SCALING_MULTIPLIER

A multiplier used to calculate the extra number of blocks we allow in the verifier, state, and block commit pipelines, on top of the lookahead limit.

Functions

gossip_best_tip_block_hashes

Run continuously, gossiping newly verified block::Hashes to peers.

is_not_found 🔒

Match the missing-block errors used by both hedging and sync recovery.

show_block_chain_progress

Logs Zebra’s estimated progress towards the chain tip every minute or so, and updates a terminal progress bar every few seconds.