Backport of Bitcoin PR #21750

[JackPiri]

Backport of Bitcoin PR #21750 (bitcoin/bitcoin#21750).

Referencing Bitcoin PR description, "[...] Indeed all locks of CNode::cs_vSend are done either when the reference
count is >0 or under the protection of CConnman::cs_vNodes and the
node being in CConnman::vNodes. [...]" still applies to Zend current codebase:

• TLSManager::threadSocketHandler: node in CConnman::vNodes and CConnman::cs_vNodes protected
• ThreadSocketHandler: node in CConnman::vNodes and CConnman::cs_vNodes protected
• ThreadMessageHandler: reference count >0
• CNode::BeginMessage/CNode::AbortMessage/CNode::EndMessage: called in PushMessage, in turn called (directly/indirectly) in ProcessMessages/SendMessages which fall in the case of reference count >0

Regarding the other two locks:

• TRY_LOCK(pnode->cs_vRecvMsg, lockRecv);: will be addressed by backport of Bitcoin PR #9441 (Net: Massive speedup. Net locks overhaul bitcoin/bitcoin#9441)

• TRY_LOCK(pnode->cs_inventory, lockInv);: can be linked to Bitcoin PR #19347 ([net] Make cs_inventory nonrecursive bitcoin/bitcoin#19347), considering the commit message "[...] The only other places that cs_inventory can be taken are:

  • In ProcessMessages() or SendMessages(), when the CNode's nRefCount
    must be >0 (see ThreadMessageHandler(), where the refcount is
    incremented before calling ProcessMessages() and SendMessages()).
  • In a ForEachNode() lambda in PeerLogicValidation::UpdatedBlockTip().
    ForEachNode() locks cs_vNodes and calls the function on the CNode
    objects in vNodes. [...]"

  in Zend codebase there are some lockings on cs_inventory in ActivateBestChain, RelayAlternativeChain, Relay but they are protected through connman->cs_vNodes, hence the lock can be removed.

[a-petrini]

Thanks, looks good to me!

[drgora]

Looks good to me, thank you!