The current trie memory database/cache that we do pruning on stores
trie nodes as binary rlp encoded blobs, and also stores the node
relationships/references for GC purposes. However, most of the trie
nodes (everything apart from a value node) is in essence just a
collection of references.
This PR switches out the RLP encoded trie blobs with the
collapsed-but-not-serialized trie nodes. This permits most of the
references to be recovered from within the node data structure,
avoiding the need to track them a second time (expensive memory wise).
This removes a golint warning: type name will be used as trie.TrieSync by
other packages, and that stutters; consider calling this Sync.
In hexToKeybytes len(hex) is even and (even+1)/2 == even/2, remove the +1.
* trie: make fullnode children hash calculation concurrently
* trie: thread out only on topmost fullnode
* trie: clean up full node children hash calculation
* trie: minor code fixups
This PR implements the new LES protocol version extensions:
* new and more efficient Merkle proofs reply format (when replying to
a multiple Merkle proofs request, we just send a single set of trie
nodes containing all necessary nodes)
* BBT (BloomBitsTrie) works similarly to the existing CHT and contains
the bloombits search data to speed up log searches
* GetTxStatusMsg returns the inclusion position or the
pending/queued/unknown state of a transaction referenced by hash
* an optional signature of new block data (number/hash/td) can be
included in AnnounceMsg to provide an option for "very light
clients" (mobile/embedded devices) to skip expensive Ethash check
and accept multiple signatures of somewhat trusted servers (still a
lot better than trusting a single server completely and retrieving
everything through RPC). The new client mode is not implemented in
this PR, just the protocol extension.
* ethdb: add Putter interface and Has method
* ethdb: improve docs and add IdealBatchSize
* ethdb: remove memory batch lock
Batches are not safe for concurrent use.
* core: use ethdb.Putter for Write* functions
This covers the easy cases.
* core/state: simplify StateSync
* trie: optimize local node check
* ethdb: add ValueSize to Batch
* core: optimize HasHeader check
This avoids one random database read get the block number. For many uses
of HasHeader, the expectation is that it's actually there. Using Has
avoids a load + decode of the value.
* core: write fast sync block data in batches
Collect writes into batches up to the ideal size instead of issuing many
small, concurrent writes.
* eth/downloader: commit larger state batches
Collect nodes into a batch up to the ideal size instead of committing
whenever a node is received.
* core: optimize HasBlock check
This avoids a random database read to get the number.
* core: use numberCache in HasHeader
numberCache has higher capacity, increasing the odds of finding the
header without a database lookup.
* core: write imported block data using a batch
Restore batch writes of state and add blocks, tx entries, receipts to
the same batch. The change also simplifies the miner.
This commit also removes posting of logs when a forked block is imported.
* core: fix DB write error handling
* ethdb: use RLock for Has
* core: fix HasBlock comment
With this commit, core/state's access to the underlying key/value database is
mediated through an interface. Database errors are tracked in StateDB and
returned by CommitTo or the new Error method.
Motivation for this change: We can remove the light client's duplicated copy of
core/state. The light client now supports node iteration, so tracing and storage
enumeration can work with the light client (not implemented in this commit).
* 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
* ethdb: remove Set
Set deadlocks immediately and isn't part of the Database interface.
* trie: add Err to Iterator
This is useful for testing because the underlying NodeIterator doesn't
need to be kept in a separate variable just to get the error.
* trie: add LeafKey to iterator, panic when not at leaf
LeafKey is useful for callers that can't interpret Path.
* trie: retry failed seek/peek in iterator Next
Instead of failing iteration irrecoverably, make it so Next retries the
pending seek or peek every time.
Smaller changes in this commit make this easier to test:
* The iterator previously returned from Next on encountering a hash
node. This caused it to visit the same path twice.
* Path returned nibbles with terminator symbol for valueNode attached
to fullNode, but removed it for valueNode attached to shortNode. Now
the terminator is always present. This makes Path unique to each node
and simplifies Leaf.
* trie: add Path to MissingNodeError
The light client trie iterator needs to know the path of the node that's
missing so it can retrieve a proof for it. NodeIterator.Path is not
sufficient because it is updated when the node is resolved and actually
visited by the iterator.
Also remove unused fields. They were added a long time ago before we
knew which fields would be needed for the light client.
The 'step' method is split into two parts, 'peek' and 'push'. peek
returns the next state but doesn't make it current.
The end of iteration was previously tracked by setting 'trie' to nil.
End of iteration is now tracked using the 'iteratorEnd' error, which is
slightly cleaner and requires less code.
