From 88577076069664b026736d8afb9b708fb26da54a Mon Sep 17 00:00:00 2001 From: Ferenc Szabo Date: Mon, 18 Feb 2019 07:38:14 +0100 Subject: p2p, swarm: fix node up races by granular locking (#18976) * swarm/network: DRY out repeated giga comment I not necessarily agree with the way we wait for event propagation. But I truly disagree with having duplicated giga comments. * p2p/simulations: encapsulate Node.Up field so we avoid data races The Node.Up field was accessed concurrently without "proper" locking. There was a lock on Network and that was used sometimes to access the field. Other times the locking was missed and we had a data race. For example: https://github.com/ethereum/go-ethereum/pull/18464 The case above was solved, but there were still intermittent/hard to reproduce races. So let's solve the issue permanently. resolves: ethersphere/go-ethereum#1146 * p2p/simulations: fix unmarshal of simulations.Node Making Node.Up field private in 13292ee897e345045fbfab3bda23a77589a271c1 broke TestHTTPNetwork and TestHTTPSnapshot. Because the default UnmarshalJSON does not handle unexported fields. Important: The fix is partial and not proper to my taste. But I cut scope as I think the fix may require a change to the current serialization format. New ticket: https://github.com/ethersphere/go-ethereum/issues/1177 * p2p/simulations: Add a sanity test case for Node.Config UnmarshalJSON * p2p/simulations: revert back to defer Unlock() pattern for Network It's a good patten to call `defer Unlock()` right after `Lock()` so (new) error cases won't miss to unlock. Let's get back to that pattern. The patten was abandoned in 85a79b3ad3c5863f8612d25c246bcfad339f36b7, while fixing a data race. That data race does not exist anymore, since the Node.Up field got hidden behind its own lock. * p2p/simulations: consistent naming for test providers Node.UnmarshalJSON * p2p/simulations: remove JSON annotation from private fields of Node As unexported fields are not serialized. * p2p/simulations: fix deadlock in Network.GetRandomDownNode() Problem: GetRandomDownNode() locks -> getDownNodeIDs() -> GetNodes() tries to lock -> deadlock On Network type, unexported functions must assume that `net.lock` is already acquired and should not call exported functions which might try to lock again. * p2p/simulations: ensure method conformity for Network Connect* methods were moved to p2p/simulations.Network from swarm/network/simulation. However these new methods did not follow the pattern of Network methods, i.e., all exported method locks the whole Network either for read or write. * p2p/simulations: fix deadlock during network shutdown `TestDiscoveryPersistenceSimulationSimAdapter` often got into deadlock. The execution was stuck on two locks, i.e, `Kademlia.lock` and `p2p/simulations.Network.lock`. Usually the test got stuck once in each 20 executions with high confidence. `Kademlia` was stuck in `Kademlia.EachAddr()` and `Network` in `Network.Stop()`. Solution: in `Network.Stop()` `net.lock` must be released before calling `node.Stop()` as stopping a node (somehow - I did not find the exact code path) causes `Network.InitConn()` to be called from `Kademlia.SuggestPeer()` and that blocks on `net.lock`. Related ticket: https://github.com/ethersphere/go-ethereum/issues/1223 * swarm/state: simplify if statement in DBStore.Put() * p2p/simulations: remove faulty godoc from private function The comment started with the wrong method name. The method is simple and self explanatory. Also, it's private. => Let's just remove the comment. (cherry picked from commit 50b872bf05b8644f14b9bea340092ced6968dd59) --- swarm/state/dbstore.go | 9 +++------ 1 file changed, 3 insertions(+), 6 deletions(-) (limited to 'swarm/state') diff --git a/swarm/state/dbstore.go b/swarm/state/dbstore.go index 147e34b23..1b541e785 100644 --- a/swarm/state/dbstore.go +++ b/swarm/state/dbstore.go @@ -88,18 +88,15 @@ func (s *DBStore) Get(key string, i interface{}) (err error) { // Put stores an object that implements Binary for a specific key. func (s *DBStore) Put(key string, i interface{}) (err error) { var bytes []byte - - marshaler, ok := i.(encoding.BinaryMarshaler) - if !ok { - if bytes, err = json.Marshal(i); err != nil { + if marshaler, ok := i.(encoding.BinaryMarshaler); ok { + if bytes, err = marshaler.MarshalBinary(); err != nil { return err } } else { - if bytes, err = marshaler.MarshalBinary(); err != nil { + if bytes, err = json.Marshal(i); err != nil { return err } } - return s.db.Put([]byte(key), bytes, nil) } -- cgit