Align proposer logic with spec

[milosevic]

if proposer(h_p , round_p ) = p then
if validValue_p != nil then
proposal ← validValue_p
else
proposal ← getValue()
broadcast ⟨PROPOSAL, h_p , round_p , proposal, validRound_p⟩.

More details can be found in https://github.com/tendermint/spec.

[ebuchman]

@milosevic can you clarify how our current implementation differs right now?

[milosevic]

In defaultDecideProposal, we first check if we have locked block, and this is what we propose; if locked block is not set we propose validBlock (if set). See

tendermint/consensus/state.go

Lines 892 to 904 in 37928cb

	if cs.LockedBlock != nil {
	// If we're locked onto a block, just choose that.
	block, blockParts = cs.LockedBlock, cs.LockedBlockParts
	} else if cs.ValidBlock != nil {
	// If there is valid block, choose that.
	block, blockParts = cs.ValidBlock, cs.ValidBlockParts
	} else {
	// Create a new proposal block from state/txs from the mempool.
	block, blockParts = cs.createProposalBlock()
	if block == nil { // on error
	return
	}
	}

. This is wrong as proposal should only be based on validBlock ( see spec).

[ebuchman]

Fixed in #2642. Thanks!