From bc325c4d1cdf499f219c79596db0b4a58c1523f5 Mon Sep 17 00:00:00 2001
From: Ethan Frey <ethanfrey@users.noreply.github.com>
Date: Tue, 30 Jan 2018 15:20:38 +0100
Subject: [PATCH] Add Query routing to rootMultiStore

---
 store/rootmultistore.go | 52 ++++++++++++++++++++++++++++++++++++++++-
 store/types.go          |  1 +
 types/errors.go         |  3 ++-
 types/result.go         |  8 +++++++
 types/store.go          |  9 +++++++
 5 files changed, 71 insertions(+), 2 deletions(-)

diff --git a/store/rootmultistore.go b/store/rootmultistore.go
index 2a0c831d81..3e6fde5c34 100644
--- a/store/rootmultistore.go
+++ b/store/rootmultistore.go
@@ -2,10 +2,13 @@ package store
 
 import (
 	"fmt"
+	"strings"
 
+	"golang.org/x/crypto/ripemd160"
+
+	abci "github.com/tendermint/abci/types"
 	dbm "github.com/tendermint/tmlibs/db"
 	"github.com/tendermint/tmlibs/merkle"
-	"golang.org/x/crypto/ripemd160"
 
 	sdk "github.com/cosmos/cosmos-sdk/types"
 )
@@ -28,6 +31,7 @@ type rootMultiStore struct {
 }
 
 var _ CommitMultiStore = (*rootMultiStore)(nil)
+var _ Queryable = (*rootMultiStore)(nil)
 
 func NewCommitMultiStore(db dbm.DB) *rootMultiStore {
 	return &rootMultiStore{
@@ -185,6 +189,52 @@ func (rs *rootMultiStore) GetStoreByName(name string) Store {
 	return rs.stores[key]
 }
 
+//---------------------- Query ------------------
+
+func (rs *rootMultiStore) Query(req abci.RequestQuery) abci.ResponseQuery {
+	// Query just routes this to a substore.
+	path := req.Path
+	storeName, subpath, err := parsePath(path)
+	if err != nil {
+		return err.Result().ToQuery()
+	}
+
+	store := rs.GetStoreByName(storeName)
+	if store == nil {
+		msg := fmt.Sprintf("no such store: %s", storeName)
+		return sdk.ErrUnknownRequest(msg).Result().ToQuery()
+	}
+	query, ok := store.(Queryable)
+	if !ok {
+		msg := fmt.Sprintf("store %s doesn't support queries", storeName)
+		return sdk.ErrUnknownRequest(msg).Result().ToQuery()
+	}
+
+	// trim the path and make the query
+	req.Path = subpath
+	res := query.Query(req)
+
+	// Note: later we have to think about adding information about
+	// the multistore -> store path to the proof
+	return res
+}
+
+// parsePath expects a format like /<storeName>[/<subpath>]
+// Must start with /, subpath may be empty
+// Returns error if it doesn't start with /
+func parsePath(path string) (storeName string, subpath string, err sdk.Error) {
+	if !strings.HasPrefix(path, "/") {
+		err = sdk.ErrUnknownRequest(fmt.Sprintf("invalid path: %s", path))
+		return
+	}
+	paths := strings.SplitN(path[1:], "/", 2)
+	storeName = paths[0]
+	if len(paths) == 2 {
+		subpath = paths[1]
+	}
+	return
+}
+
 //----------------------------------------
 
 func (rs *rootMultiStore) loadCommitStoreFromParams(id CommitID, params storeParams) (store CommitStore, err error) {
diff --git a/store/types.go b/store/types.go
index e6946fb4d5..ec842d9cf8 100644
--- a/store/types.go
+++ b/store/types.go
@@ -19,3 +19,4 @@ type CacheWrap = types.CacheWrap
 type CommitID = types.CommitID
 type StoreKey = types.StoreKey
 type StoreType = types.StoreType
+type Queryable = types.Queryable
diff --git a/types/errors.go b/types/errors.go
index 3f93045f69..a878149313 100644
--- a/types/errors.go
+++ b/types/errors.go
@@ -2,8 +2,9 @@ package types
 
 import (
 	"fmt"
-	"github.com/tendermint/go-crypto"
 	"runtime"
+
+	"github.com/tendermint/go-crypto"
 )
 
 type CodeType uint32
diff --git a/types/result.go b/types/result.go
index 412a9778de..c1afec00ce 100644
--- a/types/result.go
+++ b/types/result.go
@@ -38,3 +38,11 @@ type Result struct {
 func (res Result) IsOK() bool {
 	return res.Code.IsOK()
 }
+
+// ToQuery allows us to return sdk.Error.Result() in query responses
+func (res Result) ToQuery() abci.ResponseQuery {
+	return abci.ResponseQuery{
+		Code: uint32(res.Code),
+		Log:  res.Log,
+	}
+}
diff --git a/types/store.go b/types/store.go
index 5847091a41..e9894d0d61 100644
--- a/types/store.go
+++ b/types/store.go
@@ -3,6 +3,7 @@ package types
 import (
 	"fmt"
 
+	abci "github.com/tendermint/abci/types"
 	dbm "github.com/tendermint/tmlibs/db"
 )
 
@@ -25,6 +26,14 @@ type CommitStore interface {
 	Store
 }
 
+// Queryable allows a Store to expose internal state to the abci.Query
+// interface. Multistore can route requests to the proper Store.
+//
+// This is an optional, but useful extension to any CommitStore
+type Queryable interface {
+	Query(abci.RequestQuery) abci.ResponseQuery
+}
+
 //----------------------------------------
 // MultiStore