[#66] policy: Support IteratorChainsByPrefix method

Signed-off-by: Alexander Chuprov <a.chuprov@yadro.com>

policy/config.yml

@@ -4,4 +4,5 @@ safemethods:
   - "listChains"
   - "getChain"
   - "listChainsByPrefix"
-  - "version"
+  - "iteratorChainsByPrefix"
+  - "version"

policy/policy_contract.go

@@ -150,3 +150,9 @@ func ListChainsByPrefix(entity Kind, entityName string, prefix []byte) [][]byte
 
 	return result
 }
+
+func IteratorChainsByPrefix(entity Kind, entityName string, prefix []byte) iterator.Iterator {
+	ctx := storage.GetReadOnlyContext()
+	keyPrefix := storageKey(entity, entityName, prefix)
+	return storage.Find(ctx, keyPrefix, storage.ValuesOnly)
+}

rpcclient/policy/client.go

@@ -4,6 +4,7 @@
 package ape
 
 import (
+	"github.com/google/uuid"
 	"github.com/nspcc-dev/neo-go/pkg/core/transaction"
 	"github.com/nspcc-dev/neo-go/pkg/neorpc/result"
 	"github.com/nspcc-dev/neo-go/pkg/rpcclient/unwrap"
@@ -15,6 +16,9 @@ import (
 // Invoker is used by ContractReader to call various safe methods.
 type Invoker interface {
 	Call(contract util.Uint160, operation string, params ...any) (*result.Invoke, error)
+	CallAndExpandIterator(contract util.Uint160, method string, maxItems int, params ...any) (*result.Invoke, error)
+	TerminateSession(sessionID uuid.UUID) error
+	TraverseIterator(sessionID uuid.UUID, iterator *result.Iterator, num int) ([]stackitem.Item, error)
 }
 
 // Actor is used by Contract to call state-changing methods.
@@ -62,6 +66,20 @@ func (c *ContractReader) GetChain(entity *big.Int, entityName string, name []byt
 	return unwrap.Bytes(c.invoker.Call(c.hash, "getChain", entity, entityName, name))
 }
 
+// IteratorChainsByPrefix invokes `iteratorChainsByPrefix` method of contract.
+func (c *ContractReader) IteratorChainsByPrefix(entity *big.Int, entityName string, prefix []byte) (uuid.UUID, result.Iterator, error) {
+	return unwrap.SessionIterator(c.invoker.Call(c.hash, "iteratorChainsByPrefix", entity, entityName, prefix))
+}
+
+// IteratorChainsByPrefixExpanded is similar to IteratorChainsByPrefix (uses the same contract
+// method), but can be useful if the server used doesn't support sessions and
+// doesn't expand iterators. It creates a script that will get the specified
+// number of result items from the iterator right in the VM and return them to
+// you. It's only limited by VM stack and GAS available for RPC invocations.
+func (c *ContractReader) IteratorChainsByPrefixExpanded(entity *big.Int, entityName string, prefix []byte, _numOfIteratorItems int) ([]stackitem.Item, error) {
+	return unwrap.Array(c.invoker.CallAndExpandIterator(c.hash, "iteratorChainsByPrefix", _numOfIteratorItems, entity, entityName, prefix))
+}
+
 // ListChains invokes `listChains` method of contract.
 func (c *ContractReader) ListChains(namespace string, container string, name []byte) ([]stackitem.Item, error) {
 	return unwrap.Array(c.invoker.Call(c.hash, "listChains", namespace, container, name))

tests/policy_test.go

@@ -6,6 +6,7 @@ import (
 	"testing"
 
 	"git.frostfs.info/TrueCloudLab/frostfs-contract/policy"
+	"github.com/nspcc-dev/neo-go/pkg/core/interop/storage"
 	"github.com/nspcc-dev/neo-go/pkg/neotest"
 	"github.com/nspcc-dev/neo-go/pkg/util"
 	"github.com/nspcc-dev/neo-go/pkg/vm"
@@ -56,6 +57,9 @@ func TestPolicy(t *testing.T) {
 	checkChainsByPrefix(t, e, policy.Container, "cnr1", "", [][]byte{p2, p33})
 	checkChainsByPrefix(t, e, policy.IAM, "", "", nil)
 
+	checkChainsIteratorByPrefix(t, e, policy.Container, "cnr1", "ingress:myrule3", [][]byte{p33})
+	checkChainsIteratorByPrefix(t, e, policy.Container, "cnr1", "ingress", [][]byte{p2, p33})
+
 	t.Run("removal", func(t *testing.T) {
 		t.Run("wrong name", func(t *testing.T) {
 			e.Invoke(t, stackitem.Null{}, "removeChain", policy.Namespace, "mynamespace", "ingress")
@@ -103,6 +107,25 @@ func checkChainsByPrefix(t *testing.T, e *neotest.ContractInvoker, kind byte, en
 	checksChainsOnStack(t, s, expected)
 }
 
+func checkChainsIteratorByPrefix(t *testing.T, e *neotest.ContractInvoker, kind byte, entityName, prefix string, expected [][]byte) {
+	s, err := e.TestInvoke(t, "iteratorChainsByPrefix", kind, entityName, prefix)
+	require.NoError(t, err)
+
+	if s.Len() == 0 {
+		t.Fatal("Stack is empty")
+	}
+
+	iteratorItem := s.Pop().Value().(*storage.Iterator)
+	policys := iteratorToArray(iteratorItem)
+	require.Equal(t, len(expected), len(policys))
+
+	for i := range expected {
+		bytesPolicy, err := policys[i].TryBytes()
+		require.NoError(t, err)
+		require.Equal(t, expected[i], bytesPolicy)
+	}
+}
+
 func checksChainsOnStack(t *testing.T, s *vm.Stack, expected [][]byte) {
 	require.Equal(t, 1, s.Len())