The total difficulty is the sum of all block difficulties from genesis
to a certain block. This value was used in PoW for deciding which chain
is heavier, and thus which chain to select. Since PoS has a different
fork selection algorithm, all blocks since the merge have a difficulty
of 0, and all total difficulties are the same for the past 2 years.
Whilst the TDs are mostly useless nowadays, there was never really a
reason to mess around removing them since they are so tiny. This
reasoning changes when we go down the path of pruned chain history. In
order to reconstruct any TD, we **must** retrieve all the headers from
chain head to genesis and then iterate all the difficulties to compute
the TD.
In a world where we completely prune past chain segments (bodies,
receipts, headers), it is not possible to reconstruct the TD at all. In
a world where we still keep chain headers and prune only the rest,
reconstructing it possible as long as we process (or download) the chain
forward from genesis, but trying to snap sync the head first and
backfill later hits the same issue, the TD becomes impossible to
calculate until genesis is backfilled.
All in all, the TD is a messy out-of-state, out-of-consensus computed
field that is overall useless nowadays, but code relying on it forces
the client into certain modes of operation and prevents other modes or
other optimizations. This PR completely nukes out the TD from the node.
It doesn't compute it, it doesn't operate on it, it's as if it didn't
even exist.
Caveats:
- Whenever we have APIs that return TD (devp2p handshake, tracer, etc.)
we return a TD of 0.
- For era files, we recompute the TD during export time (fairly quick)
to retain the format content.
- It is not possible to "verify" the merge point (i.e. with TD gone, TTD
is useless). Since we're not verifying PoW any more, just blindly trust
it, not verifying but blindly trusting the many year old merge point
seems just the same trust model.
- Our tests still need to be able to generate pre and post merge blocks,
so they need a new way to split the merge without TTD. The PR introduces
a settable ttdBlock field on the consensus object which is used by tests
as the block where originally the TTD happened. This is not needed for
live nodes, we never want to generate old blocks.
- One merge transition consensus test was disabled. With a
non-operational TD, testing how the client reacts to TTD is useless, it
cannot react.
Questions:
- Should we also drop total terminal difficulty from the genesis json?
It's a number we cannot react on any more, so maybe it would be cleaner
to get rid of even more concepts.
---------
Co-authored-by: Gary Rong <garyrong0905@gmail.com>
* eth/downloader: implement beacon sync
* eth/downloader: fix a crash if the beacon chain is reduced in length
* eth/downloader: fix beacon sync start/stop thrashing data race
* eth/downloader: use a non-nil pivot even in degenerate sync requests
* eth/downloader: don't touch internal state on beacon Head retrieval
* eth/downloader: fix spelling mistakes
* eth/downloader: fix some typos
* eth: integrate legacy/beacon sync switchover and UX
* eth: handle UX wise being stuck on post-merge TTD
* core, eth: integrate the beacon client with the beacon sync
* eth/catalyst: make some warning messages nicer
* eth/downloader: remove Ethereum 1&2 notions in favor of merge
* core/beacon, eth: clean up engine API returns a bit
* eth/downloader: add skeleton extension tests
* eth/catalyst: keep non-kiln spec, handle mining on ttd
* eth/downloader: add beacon header retrieval tests
* eth: fixed spelling, commented failing tests out
* eth/downloader: review fixes
* eth/downloader: drop peers failing to deliver beacon headers
* core/rawdb: track beacon sync data in db inspect
* eth: fix review concerns
* internal/web3ext: nit
Co-authored-by: Marius van der Wijden <m.vanderwijden@live.de>
This change extracts the peer QoS tracking logic from eth/downloader, moving
it into the new package p2p/msgrate. The job of msgrate.Tracker is determining
suitable timeout values and request sizes per peer.
The snap sync scheduler now uses msgrate.Tracker instead of the hard-coded 15s
timeout. This should make the sync work better on network links with high latency.
This commit splits the eth package, separating the handling of eth and snap protocols. It also includes the capability to run snap sync (https://github.com/ethereum/devp2p/blob/master/caps/snap.md) , but does not enable it by default.
Co-authored-by: Marius van der Wijden <m.vanderwijden@live.de>
Co-authored-by: Martin Holst Swende <martin@swende.se>
* init
notes
removed some mentions of eth62, bumped protocol err too old to >=63
* remove sanity checks and bump supported protocol version up to 63
* remove 62 tests, still need to add 65
* remove 65 tests
* eth/downloader: refactor downloader + queue
downloader, fetcher: throttle-metrics, fetcher filter improvements, standalone resultcache
downloader: more accurate deliverytime calculation, less mem overhead in state requests
downloader/queue: increase underlying buffer of results, new throttle mechanism
eth/downloader: updates to tests
eth/downloader: fix up some review concerns
eth/downloader/queue: minor fixes
eth/downloader: minor fixes after review call
eth/downloader: testcases for queue.go
eth/downloader: minor change, don't set progress unless progress...
eth/downloader: fix flaw which prevented useless peers from being dropped
eth/downloader: try to fix tests
eth/downloader: verify non-deliveries against advertised remote head
eth/downloader: fix flaw with checking closed-status causing hang
eth/downloader: hashing avoidance
eth/downloader: review concerns + simplify resultcache and queue
eth/downloader: add back some locks, address review concerns
downloader/queue: fix remaining lock flaw
* eth/downloader: nitpick fixes
* eth/downloader: remove the *2*3/4 throttling threshold dance
* eth/downloader: print correct throttle threshold in stats
Co-authored-by: Péter Szilágyi <peterke@gmail.com>
* eth/downloader: separate state sync from queue
Scheduling of state node downloads hogged the downloader queue lock when
new requests were scheduled. This caused timeouts for other requests.
With this change, state sync is fully independent of all other downloads
and doesn't involve the queue at all.
State sync is started and checked on in processContent. This is slightly
awkward because processContent doesn't have a select loop. Instead, the
queue is closed by an auxiliary goroutine when state sync fails. We
tried several alternatives to this but settled on the current approach
because it's the least amount of change overall.
Handling of the pivot block has changed slightly: the queue previously
prevented import of pivot block receipts before the state of the pivot
block was available. In this commit, the receipt will be imported before
the state. This causes an annoyance where the pivot block is committed
as fast block head even when state downloads fail. Stay tuned for more
updates in this area ;)
* eth/downloader: remove cancelTimeout channel
* eth/downloader: retry state requests on timeout
* eth/downloader: improve comment
* eth/downloader: mark peers idle when state sync is done
* eth/downloader: move pivot block splitting to processContent
This change also ensures that pivot block receipts aren't imported
before the pivot block itself.
* eth/downloader: limit state node retries
* eth/downloader: improve state node error handling and retry check
* eth/downloader: remove maxStateNodeRetries
It fails the sync too much.
* eth/downloader: remove last use of cancelCh in statesync.go
Fixes TestDeliverHeadersHang*Fast and (hopefully)
the weird cancellation behaviour at the end of fast sync.
* eth/downloader: fix leak in runStateSync
* eth/downloader: don't run processFullSyncContent in LightSync mode
* eth/downloader: improve comments
* eth/downloader: fix vet, megacheck
* eth/downloader: remove unrequested tasks anyway
* eth/downloader, trie: various polishes around duplicate items
This commit explicitly tracks duplicate and unexpected state
delieveries done against a trie Sync structure, also adding
there to import info logs.
The commit moves the db batch used to commit trie changes one
level deeper so its flushed after every node insertion. This
is needed to avoid a lot of duplicate retrievals caused by
inconsistencies between Sync internals and database. A better
approach is to track not-yet-written states in trie.Sync and
flush on commit, but I'm focuing on correctness first now.
The commit fixes a regression around pivot block fail count.
The counter previously was reset to 1 if and only if a sync
cycle progressed (inserted at least 1 entry to the database).
The current code reset it already if a node was delivered,
which is not stong enough, because unless it ends up written
to disk, an attacker can just loop and attack ad infinitum.
The commit also fixes a regression around state deliveries
and timeouts. The old downloader tracked if a delivery is
stale (none of the deliveries were requestedt), in which
case it didn't mark the node idle and did not send further
requests, since it signals a past timeout. The current code
did mark it idle even on stale deliveries, which eventually
caused two requests to be in flight at the same time, making
the deliveries always stale and mass duplicating retrievals
between multiple peers.
* eth/downloader: fix state request leak
This commit fixes the hang seen sometimes while doing the state
sync. The cause of the hang was a rare combination of events:
request state data from peer, peer drops and reconnects almost
immediately. This caused a new download task to be assigned to
the peer, overwriting the old one still waiting for a timeout,
which in turned leaked the requests out, never to be retried.
The fix is to ensure that a task assignment moves any pending
one back into the retry queue.
The commit also fixes a regression with peer dropping due to
stalls. The current code considered a peer stalling if they
timed out delivering 1 item. However, the downloader never
requests only one, the minimum is 2 (attempt to fine tune
estimated latency/bandwidth). The fix is simply to drop if
a timeout is detected at 2 items.
Apart from the above bugfixes, the commit contains some code
polishes I made while debugging the hang.
* core, eth, trie: support batched trie sync db writes
* trie: rename SyncMemCache to syncMemBatch
* accounts, cmd, eth, ethdb: port logs over to new system
* ethdb: drop concept of cache distribution between dbs
* eth: fix some log nitpicks to make them nicer
Péter Szilágyi
Justin Traglia
Felix Lange
Martin Holst Swende
rene
sixdays
Martin Michlmayr
rjl493456442
Wenbiao Zheng
Yusup
Ricardo Domingos
Nick Johnson
Felix Lange