Move pending to sync package

In order to moved handling of pending to synchroniser the following
changes needed to be made:
- Add database to synchroniser, so that pending state can be served
- Blockchain and Events Filter have a pendingBlockFn() which returns the
  pending block. Due to import cycle pending struct could not be
  referenced, therefore, the anonymous function is passed.
- Add PendingBlock() to return just the pending block, this was mainly
  added to support the pendingBlockFn().
- In rpc package the pending block and state is retrieved through
  synchroniser. Therefore, receipt and transaction handler now check the
  pending block for the requested transaction/receipt.

Author: IronGauntlets

blockchain/blockchain.go

@@ -5,7 +5,6 @@ import (
 	"encoding/binary"
 	"errors"
 	"fmt"
-	"sync/atomic"
 
 	"github.com/Masterminds/semver/v3"
 	"github.com/NethermindEth/juno/core"
@@ -39,14 +38,11 @@ type Reader interface {
 	HeadState() (core.StateReader, StateCloser, error)
 	StateAtBlockHash(blockHash *felt.Felt) (core.StateReader, StateCloser, error)
 	StateAtBlockNumber(blockNumber uint64) (core.StateReader, StateCloser, error)
-	PendingState() (core.StateReader, StateCloser, error)
 
 	BlockCommitmentsByNumber(blockNumber uint64) (*core.BlockCommitments, error)
 
 	EventFilter(from *felt.Felt, keys [][]felt.Felt) (EventFilterer, error)
 
-	Pending() (*Pending, error)
-
 	Network() *utils.Network
 }
 
@@ -56,7 +52,7 @@ var (
 	SupportedStarknetVersion  = semver.MustParse("0.13.3")
 )
 
-func checkBlockVersion(protocolVersion string) error {
+func CheckBlockVersion(protocolVersion string) error {
 	blockVer, err := core.ParseBlockVersion(protocolVersion)
 	if err != nil {
 		return err
@@ -81,22 +77,21 @@ func copyWithoutPatch(v *semver.Version) *semver.Version {
 
 var _ Reader = (*Blockchain)(nil)
 
-// Todo: Remove after pending is moved to sychcroniser
-var pending atomic.Pointer[Pending]
-
 // Blockchain is responsible for keeping track of all things related to the Starknet blockchain
 type Blockchain struct {
-	network  *utils.Network
-	database db.DB
-	listener EventListener
+	network        *utils.Network
+	database       db.DB
+	listener       EventListener
+	pendingBlockFn func() *core.Block
 }
 
-func New(database db.DB, network *utils.Network) *Blockchain {
+func New(database db.DB, network *utils.Network, pendingBlockFn func() *core.Block) *Blockchain {
 	RegisterCoreTypesToEncoder()
 	return &Blockchain{
-		database: database,
-		network:  network,
-		listener: &SelectiveListener{},
+		database:       database,
+		network:        network,
+		listener:       &SelectiveListener{},
+		pendingBlockFn: pendingBlockFn,
 	}
 }
 
@@ -266,24 +261,6 @@ func (b *Blockchain) TransactionByHash(hash *felt.Felt) (core.Transaction, error
 	return transaction, b.database.View(func(txn db.Transaction) error {
 		var err error
 		transaction, err = transactionByHash(txn, hash)
-
-		// not found in the canonical blocks, try pending
-		if errors.Is(err, db.ErrKeyNotFound) {
-			var pending *Pending
-			pending, err = pendingBlock(txn)
-			if err != nil {
-				return err
-			}
-
-			for _, t := range pending.Block.Transactions {
-				if hash.Equal(t.Hash()) {
-					transaction = t
-					return nil
-				}
-			}
-			return db.ErrKeyNotFound
-		}
-
 		return err
 	})
 }
@@ -299,29 +276,6 @@ func (b *Blockchain) Receipt(hash *felt.Felt) (*core.TransactionReceipt, *felt.F
 	return receipt, blockHash, blockNumber, b.database.View(func(txn db.Transaction) error {
 		var err error
 		receipt, blockHash, blockNumber, err = receiptByHash(txn, hash)
-
-		// not found in the canonical blocks, try pending
-		if errors.Is(err, db.ErrKeyNotFound) {
-			var pending *Pending
-			pending, err = pendingBlock(txn)
-			if err != nil {
-				if !errors.Is(err, ErrPendingBlockNotFound) {
-					return err
-				}
-				return db.ErrKeyNotFound
-			}
-
-			for i, t := range pending.Block.Transactions {
-				if hash.Equal(t.Hash()) {
-					receipt = pending.Block.Receipts[i]
-					blockHash = nil
-					blockNumber = 0
-					return nil
-				}
-			}
-			return db.ErrKeyNotFound
-		}
-
 		return err
 	})
 }
@@ -407,7 +361,7 @@ func (b *Blockchain) VerifyBlock(block *core.Block) error {
 }
 
 func verifyBlock(txn db.Transaction, block *core.Block) error {
-	if err := checkBlockVersion(block.ProtocolVersion); err != nil {
+	if err := CheckBlockVersion(block.ProtocolVersion); err != nil {
 		return err
 	}
 
@@ -865,7 +819,7 @@ func (b *Blockchain) EventFilter(from *felt.Felt, keys [][]felt.Felt) (EventFilt
 		return nil, err
 	}
 
-	return newEventFilter(txn, from, keys, 0, latest, &pending), nil
+	return newEventFilter(txn, from, keys, 0, latest, b.pendingBlockFn), nil
 }
 
 // RevertHead reverts the head block
@@ -975,87 +929,3 @@ func removeTxsAndReceipts(txn db.Transaction, blockNumber, numTxs uint64) error
 
 	return nil
 }
-
-// StorePending stores a pending block given that it is for the next height
-func (b *Blockchain) StorePending(p *Pending) error {
-	err := checkBlockVersion(p.Block.ProtocolVersion)
-	if err != nil {
-		return err
-	}
-	return b.database.View(func(txn db.Transaction) error {
-		expectedParentHash := new(felt.Felt)
-		h, err := headsHeader(txn)
-		if err != nil && !errors.Is(err, db.ErrKeyNotFound) {
-			return err
-		} else if err == nil {
-			expectedParentHash = h.Hash
-		}
-
-		if !expectedParentHash.Equal(p.Block.ParentHash) {
-			return ErrParentDoesNotMatchHead
-		}
-
-		if existingPending, err := pendingBlock(txn); err == nil {
-			if existingPending.Block.TransactionCount >= p.Block.TransactionCount {
-				// ignore the incoming pending if it has fewer transactions than the one we already have
-				return nil
-			}
-		} else if !errors.Is(err, ErrPendingBlockNotFound) {
-			return err
-		}
-
-		if h != nil {
-			p.Block.Number = h.Number + 1
-		}
-		pending.Store(p)
-
-		return nil
-	})
-}
-
-func pendingBlock(txn db.Transaction) (*Pending, error) {
-	p := pending.Load()
-	if p == nil {
-		return nil, ErrPendingBlockNotFound
-	}
-
-	expectedParentHash := &felt.Zero
-	if head, err := headsHeader(txn); err == nil {
-		expectedParentHash = head.Hash
-	}
-	if p.Block.ParentHash.Equal(expectedParentHash) {
-		return p, nil
-	}
-
-	// Since the pending block in the cache is outdated remove it
-	pending.Store(nil)
-
-	return nil, ErrPendingBlockNotFound
-}
-
-// Pending returns the pending block from the database
-func (b *Blockchain) Pending() (*Pending, error) {
-	b.listener.OnRead("Pending")
-	var pending *Pending
-	return pending, b.database.View(func(txn db.Transaction) error {
-		var err error
-		pending, err = pendingBlock(txn)
-		return err
-	})
-}
-
-// PendingState returns the state resulting from execution of the pending block
-func (b *Blockchain) PendingState() (core.StateReader, StateCloser, error) {
-	b.listener.OnRead("PendingState")
-	txn, err := b.database.NewTransaction(false)
-	if err != nil {
-		return nil, nil, err
-	}
-
-	pending, err := pendingBlock(txn)
-	if err != nil {
-		return nil, nil, utils.RunAndWrapOnError(txn.Discard, err)
-	}
-
-	return NewPendingState(pending.StateUpdate.StateDiff, pending.NewClasses, core.NewState(txn)), txn.Discard, nil
-}