From d21f39160f8196efde81a85816a6739a35e51295 Mon Sep 17 00:00:00 2001
From: Ethan Frey <ethanfrey@users.noreply.github.com>
Date: Wed, 13 Dec 2017 18:34:17 +0100
Subject: [PATCH] Apply ConsensusParamChanges to state/State

---
 state/state.go  | 10 ++++++++--
 types/params.go | 38 ++++++++++++++++++++++++++++++++++++++
 2 files changed, 46 insertions(+), 2 deletions(-)

diff --git a/state/state.go b/state/state.go
index 3c9333b75..3b04cd69c 100644
--- a/state/state.go
+++ b/state/state.go
@@ -251,17 +251,22 @@ func (s *State) SetBlockAndValidators(header *types.Header, blockPartsHeader typ
 	// Update validator accums and set state variables
 	nextValSet.IncrementAccum(1)
 
+	nextParams := s.Params.ApplyChanges(
+		abciResponses.EndBlock.ConsensusParamChanges)
+
 	s.setBlockAndValidators(header.Height,
 		header.NumTxs,
 		types.BlockID{header.Hash(), blockPartsHeader},
 		header.Time,
-		prevValSet, nextValSet)
+		prevValSet, nextValSet,
+		nextParams)
 
 }
 
 func (s *State) setBlockAndValidators(height int64,
 	newTxs int64, blockID types.BlockID, blockTime time.Time,
-	prevValSet, nextValSet *types.ValidatorSet) {
+	prevValSet, nextValSet *types.ValidatorSet,
+	nextParams types.ConsensusParams) {
 
 	s.LastBlockHeight = height
 	s.LastBlockTotalTx += newTxs
@@ -269,6 +274,7 @@ func (s *State) setBlockAndValidators(height int64,
 	s.LastBlockTime = blockTime
 	s.Validators = nextValSet
 	s.LastValidators = prevValSet
+	s.Params = nextParams
 }
 
 // GetValidators returns the last and current validator sets.
diff --git a/types/params.go b/types/params.go
index 322cba612..4047913c3 100644
--- a/types/params.go
+++ b/types/params.go
@@ -2,6 +2,8 @@ package types
 
 import (
 	"github.com/pkg/errors"
+
+	abci "github.com/tendermint/abci/types"
 )
 
 const (
@@ -16,6 +18,42 @@ type ConsensusParams struct {
 	BlockGossipParams `json:"block_gossip_params"`
 }
 
+// ApplyChanges returns a new param set, overriding any
+// parameter that is non-zero in argument
+func (p ConsensusParams) ApplyChanges(c *abci.ConsensusParams) ConsensusParams {
+	if c == nil {
+		return p
+	}
+	res := p
+	// we must defensively consider any structs may be nil
+	if c.BlockSizeParams != nil {
+
+		if c.BlockSizeParams.MaxBytes != 0 {
+			res.BlockSizeParams.MaxBytes = int(c.BlockSizeParams.MaxBytes)
+		}
+		if c.BlockSizeParams.MaxTxs != 0 {
+			res.BlockSizeParams.MaxTxs = int(c.BlockSizeParams.MaxTxs)
+		}
+		if c.BlockSizeParams.MaxGas != 0 {
+			res.BlockSizeParams.MaxGas = int(c.BlockSizeParams.MaxGas)
+		}
+	}
+	if c.TxSizeParams != nil {
+		if c.TxSizeParams.MaxBytes != 0 {
+			res.TxSizeParams.MaxBytes = int(c.TxSizeParams.MaxBytes)
+		}
+		if c.TxSizeParams.MaxGas != 0 {
+			res.TxSizeParams.MaxGas = int(c.TxSizeParams.MaxGas)
+		}
+	}
+	if c.BlockGossipParams != nil {
+		if c.BlockGossipParams.BlockPartSizeBytes != 0 {
+			res.BlockGossipParams.BlockPartSizeBytes = int(c.BlockGossipParams.BlockPartSizeBytes)
+		}
+	}
+	return res
+}
+
 // BlockSizeParams contain limits on the block size.
 type BlockSizeParams struct {
 	MaxBytes int `json:"max_bytes"` // NOTE: must not be 0 nor greater than 100MB