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)

1 files changed, 5 insertions, 4 deletions

diff --git a/p2p/simulations/mocker_test.go b/p2p/simulations/mocker_test.go
index 192be1732..069040257 100644
--- a/p2p/simulations/mocker_test.go
+++ b/p2p/simulations/mocker_test.go
@@ -90,15 +90,12 @@ func TestMocker(t *testing.T) {
 		for {
 			select {
 			case event := <-events:
-				//if the event is a node Up event only
-				if event.Node != nil && event.Node.Up {
+				if isNodeUp(event) {
 					//add the correspondent node ID to the map
 					nodemap[event.Node.Config.ID] = true
 					//this means all nodes got a nodeUp event, so we can continue the test
 					if len(nodemap) == nodeCount {
 						nodesComplete = true
-						//wait for 3s as the mocker will need time to connect the nodes
-						//time.Sleep( 3 *time.Second)
 					}
 				} else if event.Conn != nil && nodesComplete {
 					connCount += 1
@@ -169,3 +166,7 @@ func TestMocker(t *testing.T) {
 		t.Fatalf("Expected empty list of nodes, got: %d", len(nodesInfo))
 	}
 }
+
+func isNodeUp(event *Event) bool {
+	return event.Node != nil && event.Node.Up()
+}