go-kosu: use a list type to store orders

packages/go-kosu/store/cosmos/list.go

@@ -0,0 +1,115 @@
+package cosmos
+
+import (
+	"fmt"
+	"strconv"
+
+	"github.com/cosmos/cosmos-sdk/types"
+
+	"github.com/ParadigmFoundation/kosu-monorepo/packages/go-kosu/store"
+)
+
+type panicCodec struct {
+	store.Codec
+}
+
+func (cdc *panicCodec) MustEncode(ptr interface{}) []byte {
+	bz, err := cdc.Encode(ptr)
+	if err != nil {
+		panic(err)
+	}
+	return bz
+}
+
+func (cdc *panicCodec) MustDecode(bz []byte, ptr interface{}) {
+	if err := cdc.Decode(bz, ptr); err != nil {
+		panic(err)
+	}
+}
+
+// LengthKey is the key for the length of the list
+func LengthKey() []byte {
+	return []byte{0x00}
+}
+
+// ElemKey is the key for the elements of the list
+func ElemKey(index uint64) []byte {
+	return append([]byte{0x01}, []byte(fmt.Sprintf("%020d", index))...)
+}
+
+// List defines an integer indexable mapper
+// It panics when the element type cannot be (un/)marshalled by the codec
+type List struct {
+	cdc   *panicCodec
+	store types.KVStore
+}
+
+// NewList constructs new List
+func NewList(cdc store.Codec, store types.KVStore) *List {
+	return &List{
+		cdc:   &panicCodec{cdc},
+		store: store,
+	}
+}
+
+// Len returns the length of the list
+// The user should check Len() before doing any actions
+func (m List) Len() (res uint64) {
+	bz := m.store.Get(LengthKey())
+	if bz == nil {
+		return 0
+	}
+
+	m.cdc.MustDecode(bz, &res)
+	return
+}
+
+// Get returns the element by its index
+func (m List) Get(index uint64, ptr interface{}) error {
+	bz := m.store.Get(ElemKey(index))
+	return m.cdc.Decode(bz, ptr)
+}
+
+// Set stores the element to the given position
+// Setting element out of range will break length counting
+// Use Push() instead of Set() to append a new element
+func (m List) Set(index uint64, value interface{}) {
+	bz := m.cdc.MustEncode(value)
+	m.store.Set(ElemKey(index), bz)
+}
+
+// Delete deletes the element in the given position
+// Other elements' indices are preserved after deletion
+// Panics when the index is out of range
+func (m List) Delete(index uint64) {
+	m.store.Delete(ElemKey(index))
+}
+
+// Push inserts the element to the end of the list
+// It will increase the length when it is called
+func (m List) Push(value interface{}) {
+	length := m.Len()
+	m.Set(length, value)
+	m.store.Set(LengthKey(), m.cdc.MustEncode(length+1))
+}
+
+// Iterate is used to iterate over all existing elements in the list
+// Return true in the continuation to break
+// Using it with Get() will return the same one with the provided element
+func (m List) Iterate(fn func(uint64) bool) {
+	iter := types.KVStorePrefixIterator(m.store, []byte{0x01})
+	defer iter.Close()
+	for ; iter.Valid(); iter.Next() {
+		k := iter.Key()
+		s := string(k[len(k)-20:])
+
+		index, err := strconv.ParseUint(s, 10, 64)
+		if err != nil {
+			panic(err)
+		}
+
+		if fn(index) {
+			break
+		}
+	}
+}

packages/go-kosu/store/cosmos/store.go

@@ -2,10 +2,6 @@ package cosmos
 
 import (
 	"encoding/hex"
-	"fmt"
-	"sort"
-	"strconv"
-	"strings"
 
 	abci "github.com/tendermint/tendermint/abci/types"
 	db "github.com/tendermint/tm-db"
@@ -30,6 +26,8 @@ type Store struct {
 	posterKey    *sdk.KVStoreKey
 	validatorKey *sdk.KVStoreKey
 	orderKey     *sdk.KVStoreKey
+
+	ordersList *List
 }
 
 // NewStore returns a new store
@@ -54,6 +52,9 @@ func NewStore(db db.DB, cdc store.Codec) *Store {
 		panic(err)
 	}
 
+	kv := s.cms.GetCommitKVStore(s.orderKey)
+	s.ordersList = NewList(cdc, kv)
+
 	return s
 }
 
@@ -207,75 +208,33 @@ func (s *Store) LastEvent() uint64 {
 	return v
 }
 
-// SetTotalOrders sets the TotalOrders
-func (s *Store) SetTotalOrders(v uint64) {
-	s.Set("totalorders", s.chainKey, v)
-}
-
-// TotalOrders gets the TotalOrders
+// TotalOrders gets the TotalOrders, this is all the received orders.
+// This number is only increased by SetOrders and never decreased
 func (s *Store) TotalOrders() uint64 {
-	var v uint64
-	s.Get("totalorders", s.chainKey, &v)
-	return v
-}
-
-// OrderKeyPrefix is the prefix to be used in the orders
-// We need a prefix to be able to use the `/subspace` query path.
-const OrderKeyPrefix = "orders"
-
-func orderKey(id int) string {
-	return fmt.Sprintf("%s%d", OrderKeyPrefix, id)
-}
-
-func parseOrderKey(key string) (int, error) {
-	key = strings.TrimPrefix(key, OrderKeyPrefix)
-	return strconv.Atoi(key)
+	return s.ordersList.Len()
 }
 
 // SetOrder creates an order in the store and remove the oldest
 // if the number of stored orders exceeds the limit value.
 // SetOrder will also update the TotalOrders counter
 func (s *Store) SetOrder(tx *types.TransactionOrder, limit int) {
-	// we generate auto-incremental IDs so that we can track the oldest order
-	var keys []int
-	s.All(s.orderKey, func(key string, _ []byte) {
-		n, err := parseOrderKey(key)
-		if err != nil {
-			panic(err)
-		}
-
-		keys = append(keys, n)
-	})
-	sort.Ints(keys)
-	// at this point we have all the IDs in order
-
-	// Delete all the orders that exceeds the limit
-	for len(keys) >= limit && limit > 0 {
-		key := keys[0]
-		s.Delete(orderKey(key), s.orderKey)
-		keys = keys[1:]
-	}
-
-	var newKey = 0
-	if len(keys) > 0 {
-		newKey = keys[len(keys)-1] + 1
+	s.ordersList.Push(tx)
+	l := s.ordersList.Len()
+	if l > uint64(limit) {
+		s.ordersList.Delete(l - uint64(limit) - 1)
 	}
-	s.Set(orderKey(newKey), s.orderKey, tx)
-
-	total := s.TotalOrders()
-	s.SetTotalOrders(total + 1)
 }
 
 // GetOrders retrieves all the available orders in the store
 func (s *Store) GetOrders() (orders []types.TransactionOrder) {
-	s.All(s.orderKey, func(_ string, bytes []byte) {
+	s.ordersList.Iterate(func(id uint64) bool {
 		var tx types.TransactionOrder
-		if err := s.Codec().Decode(bytes, &tx); err != nil {
+		if err := s.ordersList.Get(id, &tx); err != nil {
 			panic(err)
 		}
 		orders = append(orders, tx)
+		return false
 	})
-
 	return
 }
 

packages/go-kosu/store/store.go

@@ -25,7 +25,6 @@ type Store interface {
 	SetLastEvent(uint64)
 
 	TotalOrders() uint64
-	SetTotalOrders(uint64)
 	SetOrder(tx *types.TransactionOrder, limit int)
 	GetOrders() []types.TransactionOrder
 

packages/go-kosu/store/storetest/testing.go

@@ -25,7 +25,6 @@ func TestSuite(t *testing.T, f Factory) {
 		{"RoundInfo", TestRoundInfo},
 		{"ConsensusParams", TestConsensusParams},
 		{"LastEvent", TestLastEvent},
-		{"TotalOrders", TestTotalOrders},
 		{"Witness", TestWitness},
 		{"Poster", TestPoster},
 		{"Validator", TestValidator},
@@ -68,16 +67,6 @@ func TestLastEvent(t *testing.T, s store.Store) {
 	assert.Equal(t, lastEvent, s.LastEvent())
 }
 
-// TestTotalOrders verifies the LastTotalOrders storage behavior
-func TestTotalOrders(t *testing.T, s store.Store) {
-	s.SetTotalOrders(1)
-	s.SetTotalOrders(2)
-	s.SetTotalOrders(3)
-	s.SetTotalOrders(4)
-
-	assert.Equal(t, uint64(4), s.TotalOrders())
-}
-
 // TestWitness verifies the Witness storage behavior
 func TestWitness(t *testing.T, s store.Store) {
 	witnessTx := &types.TransactionWitness{