fix: Charge gas even when there are no entries in gaskv (#10218)

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## Description

Closes: #10127

Charge gas for seeks with empty ranges

---

### Author Checklist

*All items are required. Please add a note to the item if the item is not applicable and
please add links to any relevant follow up issues.*

I have...

- [ ] included the correct [type prefix](https://github.com/commitizen/conventional-commit-types/blob/v3.0.0/index.json) in the PR title
- [ ] added `!` to the type prefix if API or client breaking change
- [ ] targeted the correct branch (see [PR Targeting](https://github.com/cosmos/cosmos-sdk/blob/master/CONTRIBUTING.md#pr-targeting))
- [ ] provided a link to the relevant issue or specification
- [ ] followed the guidelines for [building modules](https://github.com/cosmos/cosmos-sdk/blob/master/docs/building-modules)
- [ ] included the necessary unit and integration [tests](https://github.com/cosmos/cosmos-sdk/blob/master/CONTRIBUTING.md#testing)
- [ ] added a changelog entry to `CHANGELOG.md`
- [ ] included comments for [documenting Go code](https://blog.golang.org/godoc)
- [ ] updated the relevant documentation or specification
- [ ] reviewed "Files changed" and left comments if necessary
- [ ] confirmed all CI checks have passed

### Reviewers Checklist

*All items are required. Please add a note if the item is not applicable and please add
your handle next to the items reviewed if you only reviewed selected items.*

I have...

- [ ] confirmed the correct [type prefix](https://github.com/commitizen/conventional-commit-types/blob/v3.0.0/index.json) in the PR title
- [ ] confirmed `!` in the type prefix if API or client breaking change
- [ ] confirmed all author checklist items have been addressed
- [ ] reviewed state machine logic
- [ ] reviewed API design and naming
- [ ] reviewed documentation is accurate
- [ ] reviewed tests and test coverage
- [ ] manually tested (if applicable)

(cherry picked from commit 4c3aa4d)

# Conflicts:
#	CHANGELOG.md

CHANGELOG.md

@@ -116,8 +116,28 @@ Security Release. No breaking changes related to 0.44.x.
 
 ### Bug Fixes
 
+<<<<<<< HEAD
 * [\#9965](https://github.com/cosmos/cosmos-sdk/pull/9965) Fixed `simd version` command output to report the right release tag.
 * (x/upgrade) [\#10189](https://github.com/cosmos/cosmos-sdk/issues/10189) Removed potential sources of non-determinism in upgrades.
+=======
+* (store) [#10218](https://github.com/cosmos/cosmos-sdk/pull/10218) Charge gas even when there are no entries while seeking.
+* (x/genutil) [#10104](https://github.com/cosmos/cosmos-sdk/pull/10104) Ensure the `init` command reads the `--home` flag value correctly.
+* [\#9651](https://github.com/cosmos/cosmos-sdk/pull/9651) Change inconsistent limit of `0` to `MaxUint64` on InfiniteGasMeter and add GasRemaining func to GasMeter.
+* [\#9639](https://github.com/cosmos/cosmos-sdk/pull/9639) Check store keys length before accessing them by making sure that `key` is of length `m+1` (for `key[n:m]`)
+* (types) [\#9627](https://github.com/cosmos/cosmos-sdk/pull/9627) Fix nil pointer panic on `NewBigIntFromInt`
+* (x/genutil) [\#9574](https://github.com/cosmos/cosmos-sdk/pull/9575) Actually use the `gentx` client tx flags (like `--keyring-dir`)
+* (x/distribution) [\#9599](https://github.com/cosmos/cosmos-sdk/pull/9599) Withdraw rewards event now includes a value attribute even if there are 0 rewards (due to situations like 100% commission).
+* (x/genutil) [\#9638](https://github.com/cosmos/cosmos-sdk/pull/9638) Added missing validator key save when recovering from mnemonic
+* [\#9762](https://github.com/cosmos/cosmos-sdk/pull/9762) The init command uses the chain-id from the client config if --chain-id is not provided
+* [\#9854](https://github.com/cosmos/cosmos-sdk/pull/9854) Fixed the `make proto-gen` to get dynamic container name based on project name for the cosmos based sdks.
+* [\#9829](https://github.com/cosmos/cosmos-sdk/pull/9829) Fixed Coin denom sorting not being checked during `Balance.Validate` check. Refactored the Validation logic to use `Coins.Validate` for `Balance.Coins`.
++ [\#9965](https://github.com/cosmos/cosmos-sdk/pull/9965) Fixed `simd version` command output to report the right release tag.
++ [\#9980](https://github.com/cosmos/cosmos-sdk/pull/9980) Returning the error when the invalid argument is passed to bank query total supply cli.
++ [\#10061](https://github.com/cosmos/cosmos-sdk/pull/10061) Ensure that `LegacyAminoPubKey` struct correctly unmarshals from JSON
+* (server) [#10016](https://github.com/cosmos/cosmos-sdk/issues/10016) Fix marshaling of index-events into server config file.
+* (x/feegrant) [\#10049](https://github.com/cosmos/cosmos-sdk/issues/10049) Fixed the error message when `period` or `period-limit` flag is not set on a feegrant grant transaction.
+* [\#10184](https://github.com/cosmos/cosmos-sdk/pull/10184) Fixed CLI tx commands to no longer explicitly require the chain-id flag as this value can come from a user config.
+>>>>>>> 4c3aa4dba (fix: Charge gas even when there are no entries in gaskv (#10218))
 
 ### Client Breaking Changes
 

store/gaskv/store.go

@@ -108,9 +108,7 @@ func (gs *Store) iterator(start, end []byte, ascending bool) types.Iterator {
 	}
 
 	gi := newGasIterator(gs.gasMeter, gs.gasConfig, parent)
-	if gi.Valid() {
-		gi.(*gasIterator).consumeSeekGas()
-	}
+	gi.(*gasIterator).consumeSeekGas()
 
 	return gi
 }
@@ -143,10 +141,7 @@ func (gi *gasIterator) Valid() bool {
 // in the iterator. It incurs a flat gas cost for seeking and a variable gas
 // cost based on the current value's length if the iterator is valid.
 func (gi *gasIterator) Next() {
-	if gi.Valid() {
-		gi.consumeSeekGas()
-	}
-
+	gi.consumeSeekGas()
 	gi.parent.Next()
 }
 
@@ -177,8 +172,10 @@ func (gi *gasIterator) Error() error {
 // consumeSeekGas consumes on each iteration step a flat gas cost and a variable gas cost
 // based on the current value's length.
 func (gi *gasIterator) consumeSeekGas() {
-	value := gi.Value()
+	if gi.Valid() {
+		value := gi.Value()
 
-	gi.gasMeter.ConsumeGas(gi.gasConfig.ReadCostPerByte*types.Gas(len(value)), types.GasValuePerByteDesc)
+		gi.gasMeter.ConsumeGas(gi.gasConfig.ReadCostPerByte*types.Gas(len(value)), types.GasValuePerByteDesc)
+	}
 	gi.gasMeter.ConsumeGas(gi.gasConfig.IterNextCostFlat, types.GasIterNextCostFlatDesc)
 }

store/gaskv/store_test.go

@@ -4,13 +4,12 @@ import (
 	"fmt"
 	"testing"
 
+	"github.com/stretchr/testify/require"
 	dbm "github.com/tendermint/tm-db"
 
 	"github.com/cosmos/cosmos-sdk/store/dbadapter"
 	"github.com/cosmos/cosmos-sdk/store/gaskv"
 	"github.com/cosmos/cosmos-sdk/store/types"
-
-	"github.com/stretchr/testify/require"
 )
 
 func bz(s string) []byte { return []byte(s) }
@@ -41,14 +40,18 @@ func TestGasKVStoreBasic(t *testing.T) {
 
 func TestGasKVStoreIterator(t *testing.T) {
 	mem := dbadapter.Store{DB: dbm.NewMemDB()}
-	meter := types.NewGasMeter(10000)
+	meter := types.NewGasMeter(100000)
 	st := gaskv.NewStore(mem, meter, types.KVGasConfig())
 	require.False(t, st.Has(keyFmt(1)))
 	require.Empty(t, st.Get(keyFmt(1)), "Expected `key1` to be empty")
 	require.Empty(t, st.Get(keyFmt(2)), "Expected `key2` to be empty")
+	require.Empty(t, st.Get(keyFmt(3)), "Expected `key3` to be empty")
+
 	st.Set(keyFmt(1), valFmt(1))
 	require.True(t, st.Has(keyFmt(1)))
 	st.Set(keyFmt(2), valFmt(2))
+	require.True(t, st.Has(keyFmt(2)))
+	st.Set(keyFmt(3), valFmt(0))
 
 	iterator := st.Iterator(nil, nil)
 	start, end := iterator.Domain()
@@ -71,8 +74,16 @@ func TestGasKVStoreIterator(t *testing.T) {
 	vb := iterator.Value()
 	require.Equal(t, vb, valFmt(2))
 	iterator.Next()
+	require.Equal(t, types.Gas(13377), meter.GasConsumed())
+	kc := iterator.Key()
+	require.Equal(t, kc, keyFmt(3))
+	vc := iterator.Value()
+	require.Equal(t, vc, valFmt(0))
+	iterator.Next()
+	require.Equal(t, types.Gas(13446), meter.GasConsumed())
 	require.False(t, iterator.Valid())
 	require.Panics(t, iterator.Next)
+	require.Equal(t, types.Gas(13476), meter.GasConsumed())
 	require.NoError(t, iterator.Error())
 
 	reverseIterator := st.ReverseIterator(nil, nil)
@@ -81,14 +92,16 @@ func TestGasKVStoreIterator(t *testing.T) {
 			t.Fatal(err)
 		}
 	})
+	require.Equal(t, reverseIterator.Key(), keyFmt(3))
+	reverseIterator.Next()
 	require.Equal(t, reverseIterator.Key(), keyFmt(2))
 	reverseIterator.Next()
 	require.Equal(t, reverseIterator.Key(), keyFmt(1))
 	reverseIterator.Next()
 	require.False(t, reverseIterator.Valid())
 	require.Panics(t, reverseIterator.Next)
 
-	require.Equal(t, types.Gas(9194), meter.GasConsumed())
+	require.Equal(t, types.Gas(13782), meter.GasConsumed())
 }
 
 func TestGasKVStoreOutOfGasSet(t *testing.T) {