From 79b1169a9ff0b54ddf3b520a70a79c78ba5c988d Mon Sep 17 00:00:00 2001
From: Determinant <ted.sybil@gmail.com>
Date: Mon, 21 Oct 2019 14:47:51 -0400
Subject: customize Blockchain code

---
 core/tx_cacher.go | 105 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 105 insertions(+)
 create mode 100644 core/tx_cacher.go

(limited to 'core/tx_cacher.go')

diff --git a/core/tx_cacher.go b/core/tx_cacher.go
new file mode 100644
index 0000000..ffac7f1
--- /dev/null
+++ b/core/tx_cacher.go
@@ -0,0 +1,105 @@
+// Copyright 2018 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package core
+
+import (
+	"runtime"
+
+	"github.com/ava-labs/go-ethereum/core/types"
+)
+
+// senderCacher is a concurrent transaction sender recoverer and cacher.
+var senderCacher = newTxSenderCacher(runtime.NumCPU())
+
+// txSenderCacherRequest is a request for recovering transaction senders with a
+// specific signature scheme and caching it into the transactions themselves.
+//
+// The inc field defines the number of transactions to skip after each recovery,
+// which is used to feed the same underlying input array to different threads but
+// ensure they process the early transactions fast.
+type txSenderCacherRequest struct {
+	signer types.Signer
+	txs    []*types.Transaction
+	inc    int
+}
+
+// txSenderCacher is a helper structure to concurrently ecrecover transaction
+// senders from digital signatures on background threads.
+type txSenderCacher struct {
+	threads int
+	tasks   chan *txSenderCacherRequest
+}
+
+// newTxSenderCacher creates a new transaction sender background cacher and starts
+// as many processing goroutines as allowed by the GOMAXPROCS on construction.
+func newTxSenderCacher(threads int) *txSenderCacher {
+	cacher := &txSenderCacher{
+		tasks:   make(chan *txSenderCacherRequest, threads),
+		threads: threads,
+	}
+	for i := 0; i < threads; i++ {
+		go cacher.cache()
+	}
+	return cacher
+}
+
+// cache is an infinite loop, caching transaction senders from various forms of
+// data structures.
+func (cacher *txSenderCacher) cache() {
+	for task := range cacher.tasks {
+		for i := 0; i < len(task.txs); i += task.inc {
+			types.Sender(task.signer, task.txs[i])
+		}
+	}
+}
+
+// recover recovers the senders from a batch of transactions and caches them
+// back into the same data structures. There is no validation being done, nor
+// any reaction to invalid signatures. That is up to calling code later.
+func (cacher *txSenderCacher) recover(signer types.Signer, txs []*types.Transaction) {
+	// If there's nothing to recover, abort
+	if len(txs) == 0 {
+		return
+	}
+	// Ensure we have meaningful task sizes and schedule the recoveries
+	tasks := cacher.threads
+	if len(txs) < tasks*4 {
+		tasks = (len(txs) + 3) / 4
+	}
+	for i := 0; i < tasks; i++ {
+		cacher.tasks <- &txSenderCacherRequest{
+			signer: signer,
+			txs:    txs[i:],
+			inc:    tasks,
+		}
+	}
+}
+
+// recoverFromBlocks recovers the senders from a batch of blocks and caches them
+// back into the same data structures. There is no validation being done, nor
+// any reaction to invalid signatures. That is up to calling code later.
+func (cacher *txSenderCacher) recoverFromBlocks(signer types.Signer, blocks []*types.Block) {
+	count := 0
+	for _, block := range blocks {
+		count += len(block.Transactions())
+	}
+	txs := make([]*types.Transaction, 0, count)
+	for _, block := range blocks {
+		txs = append(txs, block.Transactions()...)
+	}
+	cacher.recover(signer, txs)
+}
-- 
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