Merge #2500: Block conflicting redelegations

* Block conflicting redelegations

* Update PENDING.md

* Add conflicting redelegation testcase

PENDING.md

@@ -70,6 +70,7 @@ BREAKING CHANGES
     * [x/staking] \#2236 more distribution hooks for distribution
     * [x/stake] \#2394 Split up UpdateValidator into distinct state transitions applied only in EndBlock
     * [x/stake] \#2412 Added an unbonding validator queue to EndBlock to automatically update validator.Status when finished Unbonding
+    * [x/stake] \#2500 Block conflicting redelegations until we add an index
     * [x/params] Global Paramstore refactored
 
 * Tendermint

x/stake/handler_test.go

@@ -863,6 +863,48 @@ func TestTransitiveRedelegation(t *testing.T) {
 	require.True(t, got.IsOK(), "expected no error")
 }
 
+func TestConflictingRedelegation(t *testing.T) {
+	ctx, _, keeper := keep.CreateTestInput(t, false, 1000)
+	validatorAddr := sdk.ValAddress(keep.Addrs[0])
+	validatorAddr2 := sdk.ValAddress(keep.Addrs[1])
+
+	// set the unbonding time
+	params := keeper.GetParams(ctx)
+	params.UnbondingTime = 1
+	keeper.SetParams(ctx, params)
+
+	// create the validators
+	msgCreateValidator := newTestMsgCreateValidator(validatorAddr, keep.PKs[0], 10)
+	got := handleMsgCreateValidator(ctx, msgCreateValidator, keeper)
+	require.True(t, got.IsOK(), "expected no error on runMsgCreateValidator")
+
+	msgCreateValidator = newTestMsgCreateValidator(validatorAddr2, keep.PKs[1], 10)
+	got = handleMsgCreateValidator(ctx, msgCreateValidator, keeper)
+	require.True(t, got.IsOK(), "expected no error on runMsgCreateValidator")
+
+	// end block to bond them
+	EndBlocker(ctx, keeper)
+
+	// begin redelegate
+	msgBeginRedelegate := NewMsgBeginRedelegate(sdk.AccAddress(validatorAddr), validatorAddr, validatorAddr2, sdk.NewDec(5))
+	got = handleMsgBeginRedelegate(ctx, msgBeginRedelegate, keeper)
+	require.True(t, got.IsOK(), "expected no error, %v", got)
+
+	// cannot redelegate again while first redelegation still exists
+	got = handleMsgBeginRedelegate(ctx, msgBeginRedelegate, keeper)
+	require.True(t, !got.IsOK(), "expected an error, msg: %v", msgBeginRedelegate)
+
+	// progress forward in time
+	ctx = ctx.WithBlockTime(ctx.BlockHeader().Time.Add(10 * time.Second))
+
+	// complete first redelegation
+	EndBlocker(ctx, keeper)
+
+	// now should be able to redelegate again
+	got = handleMsgBeginRedelegate(ctx, msgBeginRedelegate, keeper)
+	require.True(t, got.IsOK(), "expected no error")
+}
+
 func TestUnbondingWhenExcessValidators(t *testing.T) {
 	ctx, _, keeper := keep.CreateTestInput(t, false, 1000)
 	validatorAddr1 := sdk.ValAddress(keep.Addrs[0])

x/stake/keeper/delegation.go

@@ -526,6 +526,13 @@ func (k Keeper) CompleteUnbonding(ctx sdk.Context, delAddr sdk.AccAddress, valAd
 func (k Keeper) BeginRedelegation(ctx sdk.Context, delAddr sdk.AccAddress,
 	valSrcAddr, valDstAddr sdk.ValAddress, sharesAmount sdk.Dec) (types.Redelegation, sdk.Error) {
 
+	// check if there is already a redelgation in progress from src to dst
+	// TODO quick fix, instead we should use an index, see https://github.com/cosmos/cosmos-sdk/issues/1402
+	_, found := k.GetRedelegation(ctx, delAddr, valSrcAddr, valDstAddr)
+	if found {
+		return types.Redelegation{}, types.ErrConflictingRedelegation(k.Codespace())
+	}
+
 	// check if this is a transitive redelegation
 	if k.HasReceivingRedelegation(ctx, delAddr, valSrcAddr) {
 		return types.Redelegation{}, types.ErrTransitiveRedelegation(k.Codespace())

x/stake/types/errors.go

@@ -164,6 +164,11 @@ func ErrTransitiveRedelegation(codespace sdk.CodespaceType) sdk.Error {
 		"redelegation to this validator already in progress, first redelegation to this validator must complete before next redelegation")
 }
 
+func ErrConflictingRedelegation(codespace sdk.CodespaceType) sdk.Error {
+	return sdk.NewError(codespace, CodeInvalidDelegation,
+		"conflicting redelegation from this source validator to this dest validator already exists, you must wait for it to finish")
+}
+
 func ErrBothShareMsgsGiven(codespace sdk.CodespaceType) sdk.Error {
 	return sdk.NewError(codespace, CodeInvalidInput, "both shares amount and shares percent provided")
 }