indexers: Minimize differences with upstream code.

This modifies all files in the indexers package to minimize the
differences between them and the upstream code in order to facilitate
easier syncs due to less merge conflicts as a result of superfluous
changes.

While here, it also corrects a few comments that were not updated
properly for the changes in Decred.

blockchain/indexers/addrindex.go

@@ -1,5 +1,5 @@
 // Copyright (c) 2016 The btcsuite developers
-// Copyright (c) 2016 The Decred developers
+// Copyright (c) 2016-2017 The Decred developers
 // Use of this source code is governed by an ISC
 // license that can be found in the LICENSE file.
 
@@ -143,7 +143,7 @@ var (
 
 // fetchBlockHashFunc defines a callback function to use in order to convert a
 // serialized block ID to an associated block hash.
-type fetchBlockHashFunc func(serializedID []byte) (chainhash.Hash, error)
+type fetchBlockHashFunc func(serializedID []byte) (*chainhash.Hash, error)
 
 // serializeAddrIndexEntry serializes the provided block id and transaction
 // location according to the format described in detail above.
@@ -170,7 +170,7 @@ func deserializeAddrIndexEntry(serialized []byte, region *database.BlockRegion,
 	if err != nil {
 		return err
 	}
-	region.Hash = &hash
+	region.Hash = hash
 	region.Offset = byteOrder.Uint32(serialized[4:8])
 	region.Len = byteOrder.Uint32(serialized[8:12])
 	return nil
@@ -390,7 +390,7 @@ func dbRemoveAddrIndexEntries(bucket internalBucket, addrKey [addrKeySize]byte,
 		return nil
 	}
 
-	// Loop fowards through the levels while removing entries until the
+	// Loop forwards through the levels while removing entries until the
 	// specified number has been removed.  This will potentially result in
 	// entirely empty lower levels which will be backfilled below.
 	var highestLoadedLevel uint8
@@ -715,52 +715,50 @@ func (idx *AddrIndex) indexPkScript(data writeIndexData, scriptVersion uint16, p
 }
 
 // indexBlock extract all of the standard addresses from all of the transactions
-// in the passed block and maps each of them to the assocaited transaction using
-// the passed map.
+// in the parent of the passed block (if they were valid) and all of the stake
+// transactions in the passed block, and maps each of them to the associated
+// transaction using the passed map.
 func (idx *AddrIndex) indexBlock(data writeIndexData, block, parent *dcrutil.Block, view *blockchain.UtxoViewpoint) {
-	regularTxTreeValid := dcrutil.IsFlagSet16(block.MsgBlock().Header.VoteBits,
-		dcrutil.BlockValid)
-	var stakeStartIdx int
-	if regularTxTreeValid {
-		for txIdx, tx := range parent.Transactions() {
-			// Coinbases do not reference any inputs.  Since the block is
-			// required to have already gone through full validation, it has
-			// already been proven on the first transaction in the block is
-			// a coinbase.
-			if txIdx != 0 {
-				for _, txIn := range tx.MsgTx().TxIn {
-					// The view should always have the input since
-					// the index contract requires it, however, be
-					// safe and simply ignore any missing entries.
-					origin := &txIn.PreviousOutPoint
-					entry := view.LookupEntry(&origin.Hash)
-					if entry == nil {
-						log.Warnf("Missing input %v for tx %v while "+
-							"indexing block %v (height %v)\n", origin.Hash,
-							tx.Hash(), block.Hash(), block.Height())
-						continue
-					}
-
-					version := entry.ScriptVersionByIndex(origin.Index)
-					pkScript := entry.PkScriptByIndex(origin.Index)
-					txType := entry.TransactionType()
-					idx.indexPkScript(data, version, pkScript, txIdx,
-						txType == stake.TxTypeSStx)
+	var parentRegularTxs []*dcrutil.Tx
+	if approvesParent(block) {
+		parentRegularTxs = parent.Transactions()
+	}
+	for txIdx, tx := range parentRegularTxs {
+		// Coinbases do not reference any inputs.  Since the block is
+		// required to have already gone through full validation, it has
+		// already been proven on the first transaction in the block is
+		// a coinbase.
+		if txIdx != 0 {
+			for _, txIn := range tx.MsgTx().TxIn {
+				// The view should always have the input since
+				// the index contract requires it, however, be
+				// safe and simply ignore any missing entries.
+				origin := &txIn.PreviousOutPoint
+				entry := view.LookupEntry(&origin.Hash)
+				if entry == nil {
+					log.Warnf("Missing input %v for tx %v while "+
+						"indexing block %v (height %v)\n", origin.Hash,
+						tx.Hash(), block.Hash(), block.Height())
+					continue
 				}
-			}
 
-			for _, txOut := range tx.MsgTx().TxOut {
-				idx.indexPkScript(data, txOut.Version, txOut.PkScript, txIdx,
-					false)
+				version := entry.ScriptVersionByIndex(origin.Index)
+				pkScript := entry.PkScriptByIndex(origin.Index)
+				txType := entry.TransactionType()
+				idx.indexPkScript(data, version, pkScript, txIdx,
+					txType == stake.TxTypeSStx)
 			}
 		}
 
-		stakeStartIdx = len(parent.Transactions())
+		for _, txOut := range tx.MsgTx().TxOut {
+			idx.indexPkScript(data, txOut.Version, txOut.PkScript, txIdx,
+				false)
+		}
 	}
 
 	for txIdx, tx := range block.STransactions() {
 		msgTx := tx.MsgTx()
-		thisTxOffset := txIdx + stakeStartIdx
+		thisTxOffset := txIdx + len(parentRegularTxs)
 
 		isSSGen, _ := stake.IsSSGen(msgTx)
 		for i, txIn := range msgTx.TxIn {
@@ -801,24 +799,21 @@ func (idx *AddrIndex) indexBlock(data writeIndexData, block, parent *dcrutil.Blo
 // the transactions in the block involve.
 //
 // This is part of the Indexer interface.
-func (idx *AddrIndex) ConnectBlock(dbTx database.Tx, block, parent *dcrutil.Block,
-	view *blockchain.UtxoViewpoint) error {
+func (idx *AddrIndex) ConnectBlock(dbTx database.Tx, block, parent *dcrutil.Block, view *blockchain.UtxoViewpoint) error {
 	// The offset and length of the transactions within the serialized
 	// block for the regular transactions of the previous block, if
 	// applicable.
-	regularTxTreeValid := dcrutil.IsFlagSet16(block.MsgBlock().Header.VoteBits,
-		dcrutil.BlockValid)
 	var parentTxLocs []wire.TxLoc
 	var parentBlockID uint32
-	if regularTxTreeValid && block.Height() > 1 {
+	if approvesParent(block) && block.Height() > 1 {
 		var err error
 		parentTxLocs, _, err = parent.TxLoc()
 		if err != nil {
 			return err
 		}
 
 		parentHash := parent.Hash()
-		parentBlockID, err = dbFetchBlockIDByHash(dbTx, *parentHash)
+		parentBlockID, err = dbFetchBlockIDByHash(dbTx, parentHash)
 		if err != nil {
 			return err
 		}
@@ -838,7 +833,7 @@ func (idx *AddrIndex) ConnectBlock(dbTx database.Tx, block, parent *dcrutil.Bloc
 
 	// Get the internal block ID associated with the block.
 	blockHash := block.Hash()
-	blockID, err := dbFetchBlockIDByHash(dbTx, *blockHash)
+	blockID, err := dbFetchBlockIDByHash(dbTx, blockHash)
 	if err != nil {
 		return err
 	}
@@ -916,7 +911,7 @@ func (idx *AddrIndex) TxRegionsForAddress(dbTx database.Tx, addr dcrutil.Address
 	err = idx.db.View(func(dbTx database.Tx) error {
 		// Create closure to lookup the block hash given the ID using
 		// the database transaction.
-		fetchBlockHash := func(id []byte) (chainhash.Hash, error) {
+		fetchBlockHash := func(id []byte) (*chainhash.Hash, error) {
 			// Deserialize and populate the result.
 			return dbFetchBlockHashBySerializedID(dbTx, id)
 		}

blockchain/indexers/common.go

@@ -1,5 +1,5 @@
 // Copyright (c) 2016 The btcsuite developers
-// Copyright (c) 2016 The Decred developers
+// Copyright (c) 2016-2017 The Decred developers
 // Use of this source code is governed by an ISC
 // license that can be found in the LICENSE file.
 
@@ -89,3 +89,11 @@ type internalBucket interface {
 	Put(key []byte, value []byte) error
 	Delete(key []byte) error
 }
+
+// approvesParent returns whether or not the vote bits in the header of the
+// passed block indicate the regular transaction tree of the parent block should
+// be considered valid.
+func approvesParent(block *dcrutil.Block) bool {
+	return dcrutil.IsFlagSet16(block.MsgBlock().Header.VoteBits,
+		dcrutil.BlockValid)
+}

blockchain/indexers/existsaddrindex.go

@@ -1,4 +1,4 @@
-// Copyright (c) 2016 The Decred developers
+// Copyright (c) 2016-2017 The Decred developers
 // Use of this source code is governed by an ISC
 // license that can be found in the LICENSE file.
 
@@ -214,10 +214,8 @@ func (idx *ExistsAddrIndex) ExistsAddresses(addrs []dcrutil.Address) ([]bool, er
 //
 // This is part of the Indexer interface.
 func (idx *ExistsAddrIndex) ConnectBlock(dbTx database.Tx, block, parent *dcrutil.Block, view *blockchain.UtxoViewpoint) error {
-	regularTxTreeValid := dcrutil.IsFlagSet16(block.MsgBlock().Header.VoteBits,
-		dcrutil.BlockValid)
 	var parentTxs []*dcrutil.Tx
-	if regularTxTreeValid && block.Height() > 1 {
+	if approvesParent(block) && block.Height() > 1 {
 		parentTxs = parent.Transactions()
 	}
 	blockTxns := block.STransactions()