btcstaking: avoid using ctx in APIs (#172)

x/btcstaking/keeper/grpc_query.go

@@ -136,28 +136,9 @@ func (k Keeper) FinalityProviderCurrentPower(ctx context.Context, req *types.Que
 		return nil, status.Errorf(codes.InvalidArgument, "failed to unmarshal finality provider BTC PK hex: %v", err)
 	}
 
-	sdkCtx := sdk.UnwrapSDKContext(ctx)
-	power := uint64(0)
-	curHeight := uint64(sdkCtx.HeaderInfo().Height)
-
-	// if voting power table is recorded at the current height, use this voting power
-	if k.HasVotingPowerTable(sdkCtx, curHeight) {
-		power = k.GetVotingPower(sdkCtx, fpBTCPK.MustMarshal(), curHeight)
-	} else {
-		// NOTE: it's possible that the voting power is not recorded at the current height,
-		// e.g., `EndBlock` is not reached yet
-		// in this case, we use the last height
-
-		// ensure curHeight > 0 thus won't over flow
-		if curHeight == 0 {
-			return &types.QueryFinalityProviderCurrentPowerResponse{Height: 0, VotingPower: 0}, nil
-		}
-
-		curHeight -= 1
-		power = k.GetVotingPower(sdkCtx, fpBTCPK.MustMarshal(), curHeight)
-	}
+	height, power := k.GetCurrentVotingPower(ctx, *fpBTCPK)
 
-	return &types.QueryFinalityProviderCurrentPowerResponse{Height: curHeight, VotingPower: power}, nil
+	return &types.QueryFinalityProviderCurrentPowerResponse{Height: height, VotingPower: power}, nil
 }
 
 // ActiveFinalityProvidersAtHeight returns the active finality providers at the provided height

x/btcstaking/keeper/grpc_query_test.go

@@ -331,11 +331,12 @@ func FuzzFinalityProviderCurrentVotingPower(f *testing.F) {
 		require.Equal(t, randomHeight, resp.Height)
 		require.Equal(t, randomPower, resp.VotingPower)
 
-		// but no more
+		// test the case when the finality provider has 0 voting power
 		ctx = datagen.WithCtxHeight(ctx, randomHeight+2)
+		keeper.SetVotingPower(ctx, fp.BtcPk.MustMarshal(), randomHeight+2, 0)
 		resp, err = keeper.FinalityProviderCurrentPower(ctx, req)
 		require.NoError(t, err)
-		require.Equal(t, randomHeight+1, resp.Height)
+		require.Equal(t, randomHeight+2, resp.Height)
 		require.Equal(t, uint64(0), resp.VotingPower)
 	})
 }

x/btcstaking/keeper/voting_power_table.go

@@ -107,6 +107,39 @@ func (k Keeper) GetVotingPower(ctx context.Context, fpBTCPK []byte, height uint6
 	return sdk.BigEndianToUint64(powerBytes)
 }
 
+// GetCurrentVotingPower gets the voting power of a given finality provider at the current height
+// NOTE: it's possible that the voting power table is 1 block behind CometBFT, e.g., when `BeginBlock`
+// hasn't executed yet
+func (k Keeper) GetCurrentVotingPower(ctx context.Context, fpBTCPK []byte) (uint64, uint64) {
+	// find the last recorded voting power table via iterator
+	storeAdapter := runtime.KVStoreAdapter(k.storeService.OpenKVStore(ctx))
+	store := prefix.NewStore(storeAdapter, types.VotingPowerKey)
+	iter := store.ReverseIterator(nil, nil)
+	defer iter.Close()
+
+	// no voting power table is known yet, return 0
+	if !iter.Valid() {
+		return 0, 0
+	}
+
+	// there is known voting power table, find the last height
+	lastHeight := sdk.BigEndianToUint64(iter.Key())
+	storeAtHeight := prefix.NewStore(store, sdk.Uint64ToBigEndian(lastHeight))
+
+	// if the finality provider is not known, return 0 voting power
+	if !k.HasFinalityProvider(ctx, fpBTCPK) {
+		return lastHeight, 0
+	}
+
+	// find the voting power of this finality provider
+	powerBytes := storeAtHeight.Get(fpBTCPK)
+	if len(powerBytes) == 0 {
+		return lastHeight, 0
+	}
+
+	return lastHeight, sdk.BigEndianToUint64(powerBytes)
+}
+
 // HasVotingPowerTable checks if the voting power table exists at a given height
 func (k Keeper) HasVotingPowerTable(ctx context.Context, height uint64) bool {
 	store := k.votingPowerStore(ctx, height)