core: add lightweight HasCanonicalTransaction check

We only had the getter exposed, which is heavy compared to
just checking the existence.

Signed-off-by: Csaba Kiraly <csaba.kiraly@gmail.com>

core/blockchain_reader.go

@@ -321,6 +321,25 @@ func (bc *BlockChain) GetAncestor(hash common.Hash, number, ancestor uint64, max
 	return bc.hc.GetAncestor(hash, number, ancestor, maxNonCanonical)
 }
 
+// HasCanonicalTransaction is a lightweight check to see if a transaction is present
+// in the indexed part of the canonical chain without retrieving the transaction itself.
+// It's view is limited to the indexed part of the chain, so very old transactions
+// might fail the check if the indexer was constrained, or indexing is still in progress.
+func (bc *BlockChain) HasCanonicalTransaction(hash common.Hash) bool {
+	bc.txLookupLock.RLock()
+	defer bc.txLookupLock.RUnlock()
+
+	// Check in memory cache first
+	if _, exist := bc.txLookupCache.Get(hash); exist {
+		return true
+	}
+	// Fallback to database lookup, without reading the transaction itself
+	if rawdb.HasCanonicalTransaction(bc.db, hash) {
+		return true
+	}
+	return false
+}
+
 // GetCanonicalTransaction retrieves the lookup along with the transaction
 // itself associate with the given transaction hash.
 //

core/rawdb/accessors_indexes.go

@@ -174,6 +174,12 @@ func findTxInBlockBody(blockbody rlp.RawValue, target common.Hash) (*types.Trans
 	return nil, 0, errors.New("transaction not found")
 }
 
+// HasCanonicalTransaction checks whether a specific transaction is in the database.
+func HasCanonicalTransaction(db ethdb.Reader, hash common.Hash) bool {
+	blockNumber := ReadTxLookupEntry(db, hash)
+	return blockNumber != nil
+}
+
 // ReadCanonicalTransaction retrieves a specific transaction from the database, along
 // with its added positional metadata. Notably, only the transaction in the canonical
 // chain is visible.