Bucky/fix evidence halt (#34)

* consensus: createProposalBlock function

* blockExecutor.CreateProposalBlock

- factored out of consensus pkg into a method on blockExec
- new private interfaces for mempool ("txNotifier") and evpool with one function each
- consensus tests still require more mempool methods

* failing test for CreateProposalBlock

* Fix bug in include evidece into block

* evidence: change maxBytes to maxSize

* MaxEvidencePerBlock

- changed to return both the max number and the max bytes
- preparation for #2590

* changelog

* fix linter

* Fix from review

Co-Authored-By: ebuchman <ethan@coinculture.info>

state/execution.go

@@ -29,7 +29,8 @@ type BlockExecutor struct {
 	// events
 	eventBus types.BlockEventPublisher
 
-	// update these with block results after commit
+	// manage the mempool lock during commit
+	// and update both with block results after commit.
 	mempool Mempool
 	evpool  EvidencePool
 
@@ -73,6 +74,31 @@ func (blockExec *BlockExecutor) SetEventBus(eventBus types.BlockEventPublisher)
 	blockExec.eventBus = eventBus
 }
 
+// CreateProposalBlock calls state.MakeBlock with evidence from the evpool
+// and txs from the mempool. The max bytes must be big enough to fit the commit.
+// Up to 1/10th of the block space is allcoated for maximum sized evidence.
+// The rest is given to txs, up to the max gas.
+func (blockExec *BlockExecutor) CreateProposalBlock(
+	height int64,
+	state State, commit *types.Commit,
+	proposerAddr []byte,
+) (*types.Block, *types.PartSet) {
+
+	maxBytes := state.ConsensusParams.BlockSize.MaxBytes
+	maxGas := state.ConsensusParams.BlockSize.MaxGas
+
+	// Fetch a limited amount of valid evidence
+	maxNumEvidence, _ := types.MaxEvidencePerBlock(maxBytes)
+	evidence := blockExec.evpool.PendingEvidence(maxNumEvidence)
+
+	// Fetch a limited amount of valid txs
+	maxDataBytes := types.MaxDataBytes(maxBytes, state.Validators.Size(), len(evidence))
+	txs := blockExec.mempool.ReapMaxBytesMaxGas(maxDataBytes, maxGas)
+
+	return state.MakeBlock(height, txs, commit, evidence, proposerAddr)
+
+}
+
 // ValidateBlock validates the given block against the given state.
 // If the block is invalid, it returns an error.
 // Validation does not mutate state, but does require historical information from the stateDB,