Replace map[a]bool with map[a]struct{}

The later uses no memory storage for values and provides the same
functionality.

reorganization_test.go

@@ -57,14 +57,14 @@ func TestReorganization(t *testing.T) {
 	chain.DisableCheckpoints(true)
 	btcchain.TstSetCoinbaseMaturity(1)
 
-	expectedOrphans := map[int]bool{5: true, 6: true}
+	expectedOrphans := map[int]struct{}{5: struct{}{}, 6: struct{}{}}
 	for i := 1; i < len(blocks); i++ {
 		isOrphan, err := chain.ProcessBlock(blocks[i], btcchain.BFNone)
 		if err != nil {
 			t.Errorf("ProcessBlock fail on block %v: %v\n", i, err)
 			return
 		}
-		if isOrphan && !expectedOrphans[i] {
+		if _, ok := expectedOrphans[i]; !ok && isOrphan {
 			t.Errorf("ProcessBlock incorrectly returned block %v "+
 				"is an orphan\n", i)
 		}

txlookup.go

@@ -100,7 +100,7 @@ func disconnectTransactions(txStore TxStore, block *btcutil.Block) error {
 // transactions from the point of view of the end of the main chain.  It takes
 // a flag which specifies whether or not fully spent transaction should be
 // included in the results.
-func fetchTxStoreMain(db btcdb.Db, txSet map[btcwire.ShaHash]bool, includeSpent bool) TxStore {
+func fetchTxStoreMain(db btcdb.Db, txSet map[btcwire.ShaHash]struct{}, includeSpent bool) TxStore {
 	// Just return an empty store now if there are no requested hashes.
 	txStore := make(TxStore)
 	if len(txSet) == 0 {
@@ -160,7 +160,7 @@ func fetchTxStoreMain(db btcdb.Db, txSet map[btcwire.ShaHash]bool, includeSpent
 // chain).  Another scenario is where a transaction exists from the point of
 // view of the main chain, but doesn't exist in a side chain that branches
 // before the block that contains the transaction on the main chain.
-func (b *BlockChain) fetchTxStore(node *blockNode, txSet map[btcwire.ShaHash]bool) (TxStore, error) {
+func (b *BlockChain) fetchTxStore(node *blockNode, txSet map[btcwire.ShaHash]struct{}) (TxStore, error) {
 	// Get the previous block node.  This function is used over simply
 	// accessing node.parent directly as it will dynamically create previous
 	// block nodes as needed.  This helps allow only the pieces of the chain
@@ -245,7 +245,7 @@ func (b *BlockChain) fetchInputTransactions(node *blockNode, block *btcutil.Bloc
 	// Loop through all of the transaction inputs (except for the coinbase
 	// which has no inputs) collecting them into sets of what is needed and
 	// what is already known (in-flight).
-	txNeededSet := make(map[btcwire.ShaHash]bool)
+	txNeededSet := make(map[btcwire.ShaHash]struct{})
 	txStore := make(TxStore)
 	for i, tx := range transactions[1:] {
 		for _, txIn := range tx.MsgTx().TxIn {
@@ -274,7 +274,7 @@ func (b *BlockChain) fetchInputTransactions(node *blockNode, block *btcutil.Bloc
 				txD.Spent = make([]bool, len(originTx.MsgTx().TxOut))
 				txD.Err = nil
 			} else {
-				txNeededSet[*originHash] = true
+				txNeededSet[*originHash] = struct{}{}
 			}
 		}
 	}
@@ -302,10 +302,10 @@ func (b *BlockChain) FetchTransactionStore(tx *btcutil.Tx) (TxStore, error) {
 	// Create a set of needed transactions from the transactions referenced
 	// by the inputs of the passed transaction.  Also, add the passed
 	// transaction itself as a way for the caller to detect duplicates.
-	txNeededSet := make(map[btcwire.ShaHash]bool)
+	txNeededSet := make(map[btcwire.ShaHash]struct{})
-	txNeededSet[*tx.Sha()] = true
+	txNeededSet[*tx.Sha()] = struct{}{}
 	for _, txIn := range tx.MsgTx().TxIn {
-		txNeededSet[txIn.PreviousOutpoint.Hash] = true
+		txNeededSet[txIn.PreviousOutpoint.Hash] = struct{}{}
 	}
 
 	// Request the input transactions from the point of view of the end of

validate.go

@@ -243,13 +243,13 @@ func CheckTransactionSanity(tx *btcutil.Tx) error {
 	}
 
 	// Check for duplicate transaction inputs.
-	existingTxOut := make(map[btcwire.OutPoint]bool)
+	existingTxOut := make(map[btcwire.OutPoint]struct{})
 	for _, txIn := range msgTx.TxIn {
 		if _, exists := existingTxOut[txIn.PreviousOutpoint]; exists {
 			return ruleError(ErrDuplicateTxInputs, "transaction "+
 				"contains duplicate inputs")
 		}
-		existingTxOut[txIn.PreviousOutpoint] = true
+		existingTxOut[txIn.PreviousOutpoint] = struct{}{}
 	}
 
 	// Coinbase script length must be between min and max length.
@@ -518,7 +518,7 @@ func checkBlockSanity(block *btcutil.Block, powLimit *big.Int, flags BehaviorFla
 	// Check for duplicate transactions.  This check will be fairly quick
 	// since the transaction hashes are already cached due to building the
 	// merkle tree above.
-	existingTxHashes := make(map[btcwire.ShaHash]bool)
+	existingTxHashes := make(map[btcwire.ShaHash]struct{})
 	for _, tx := range transactions {
 		hash := tx.Sha()
 		if _, exists := existingTxHashes[*hash]; exists {
@@ -526,7 +526,7 @@ func checkBlockSanity(block *btcutil.Block, powLimit *big.Int, flags BehaviorFla
 				"transaction %v", hash)
 			return ruleError(ErrDuplicateTx, str)
 		}
-		existingTxHashes[*hash] = true
+		existingTxHashes[*hash] = struct{}{}
 	}
 
 	// The number of signature operations must be less than the maximum
@@ -611,9 +611,9 @@ func isTransactionSpent(txD *TxData) bool {
 func (b *BlockChain) checkBIP0030(node *blockNode, block *btcutil.Block) error {
 	// Attempt to fetch duplicate transactions for all of the transactions
 	// in this block from the point of view of the parent node.
-	fetchSet := make(map[btcwire.ShaHash]bool)
+	fetchSet := make(map[btcwire.ShaHash]struct{})
 	for _, tx := range block.Transactions() {
-		fetchSet[*tx.Sha()] = true
+		fetchSet[*tx.Sha()] = struct{}{}
 	}
 	txResults, err := b.fetchTxStore(node, fetchSet)
 	if err != nil {