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Make rescan faster by avoiding hash copies.

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Copying the RIPEMD160 after SHA256 hash result into a new stack array
to be used as a map lookup key can be quite expensive, and this should
be avoided if possible on intensive tasks such as rescans.  This
change takes advantage of the new Hash160 methods of the
AddressPubKeyHash and AddressScriptHash types to use the address's
underlying hash array directly, rather than creating a copy from the
ScriptAddress result.

Unfortunately, for AddressPubKey, ScriptAddress may return either a
byte slice of len 33 or 65 depending on whether the pubkey is
compressed or not, so no such straightforward optimization is
possible.

As a result of this change, I have seen rescans perform roughly 3.5x
faster than before.
This commit is contained in:
Josh Rickmar 2014-04-20 15:51:04 -05:00
parent 1e75ccc9b9
commit f88db561f1
1 changed files with 8 additions and 12 deletions
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20
rpcwebsocket.go
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@ -1479,9 +1479,10 @@ type rescanKeys struct {
// rescanBlock rescans all transactions in a single block. This is a helper
// function for handleRescan.
func rescanBlock(wsc *wsClient, lookups *rescanKeys, blk *btcutil.Block) {
// Vars used for map keys. The item being checked is copied into
// these and then used as the lookup key. Saves on GC.
var ripemd160Hash [ripemd160.Size]byte
// Vars used for map keys. If necessary, the byte slice for each
// checked item is copied into and then used as the lookup key.
// This is quite a bit more efficient than creating an address
// string as it saves on GC and performs less copying.
var compressedPubkey [33]byte
var uncompressedPubkey [65]byte
var outpoint btcwire.OutPoint
@ -1532,14 +1533,12 @@ func rescanBlock(wsc *wsClient, lookups *rescanKeys, blk *btcutil.Block) {
for _, addr := range addrs {
switch a := addr.(type) {
case *btcutil.AddressPubKeyHash:
copy(ripemd160Hash[:], a.ScriptAddress())
if _, ok := lookups.pubKeyHashes[ripemd160Hash]; !ok {
if _, ok := lookups.pubKeyHashes[*a.Hash160()]; !ok {
continue
}
case *btcutil.AddressScriptHash:
copy(ripemd160Hash[:], a.ScriptAddress())
if _, ok := lookups.scriptHashes[ripemd160Hash]; !ok {
if _, ok := lookups.scriptHashes[*a.Hash160()]; !ok {
continue
}
@ -1642,7 +1641,6 @@ func handleRescan(wsc *wsClient, icmd btcjson.Cmd) (interface{}, *btcjson.Error)
uncompressedPubkeys: map[[65]byte]struct{}{},
unspent: map[btcwire.OutPoint]struct{}{},
}
var ripemd160Hash [ripemd160.Size]byte
var compressedPubkey [33]byte
var uncompressedPubkey [65]byte
for _, addrStr := range cmd.Addresses {
@ -1656,12 +1654,10 @@ func handleRescan(wsc *wsClient, icmd btcjson.Cmd) (interface{}, *btcjson.Error)
}
switch a := addr.(type) {
case *btcutil.AddressPubKeyHash:
copy(ripemd160Hash[:], a.ScriptAddress())
lookups.pubKeyHashes[ripemd160Hash] = struct{}{}
lookups.pubKeyHashes[*a.Hash160()] = struct{}{}
case *btcutil.AddressScriptHash:
copy(ripemd160Hash[:], a.ScriptAddress())
lookups.scriptHashes[ripemd160Hash] = struct{}{}
lookups.scriptHashes[*a.Hash160()] = struct{}{}
case *btcutil.AddressPubKey:
pubkeyBytes := a.ScriptAddress()