From 0efd6a881afac0b3082f3b1e8780e3438eea5b02 Mon Sep 17 00:00:00 2001
From: Ethan Buchman <ethan@coinculture.info>
Date: Fri, 27 Feb 2015 16:05:03 -0500
Subject: public functions for making chains on the fly

---
 core/chain_makers.go | 131 +++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 131 insertions(+)
 create mode 100644 core/chain_makers.go

(limited to 'core/chain_makers.go')

diff --git a/core/chain_makers.go b/core/chain_makers.go
new file mode 100644
index 000000000..eb43f8aa0
--- /dev/null
+++ b/core/chain_makers.go
@@ -0,0 +1,131 @@
+package core
+
+import (
+	"fmt"
+	"github.com/ethereum/go-ethereum/core/types"
+	"github.com/ethereum/go-ethereum/ethutil"
+	"github.com/ethereum/go-ethereum/event"
+	"github.com/ethereum/go-ethereum/pow"
+	"github.com/ethereum/go-ethereum/state"
+	"math/big"
+)
+
+// So we can generate blocks easily
+type FakePow struct{}
+
+func (f FakePow) Search(block pow.Block, stop <-chan struct{}) []byte { return nil }
+func (f FakePow) Verify(block pow.Block) bool                         { return true }
+func (f FakePow) GetHashrate() int64                                  { return 0 }
+func (f FakePow) Turbo(bool)                                          {}
+
+func NewBlockFromParent(addr []byte, parent *types.Block) *types.Block {
+	return newBlockFromParent(addr, parent)
+}
+
+func MakeBlock(bman *BlockProcessor, parent *types.Block, i int, db ethutil.Database) *types.Block {
+	return makeBlock(bman, parent, i, db)
+}
+
+func MakeChain(bman *BlockProcessor, parent *types.Block, max int, db ethutil.Database) types.Blocks {
+	return makeChain(bman, parent, max, db)
+}
+
+func NewChainMan(block *types.Block, eventMux *event.TypeMux, db ethutil.Database) *ChainManager {
+	return newChainManager(block, eventMux, db)
+}
+
+func NewBlockProc(db ethutil.Database, txpool *TxPool, cman *ChainManager, eventMux *event.TypeMux) *BlockProcessor {
+	return newBlockProcessor(db, txpool, cman, eventMux)
+}
+
+func NewCanonical(n int, db ethutil.Database) (*BlockProcessor, error) {
+	return newCanonical(n, db)
+}
+
+func newBlockFromParent(addr []byte, parent *types.Block) *types.Block {
+	block := types.NewBlock(parent.Hash(), addr, parent.Root(), ethutil.BigPow(2, 32), nil, "")
+
+	block.SetUncles(nil)
+	block.SetTransactions(nil)
+	block.SetReceipts(nil)
+
+	header := block.Header()
+	header.Difficulty = CalcDifficulty(block, parent)
+	header.Number = new(big.Int).Add(parent.Header().Number, ethutil.Big1)
+	header.GasLimit = CalcGasLimit(parent, block)
+
+	block.Td = parent.Td
+
+	return block
+}
+
+// Actually make a block by simulating what miner would do
+func makeBlock(bman *BlockProcessor, parent *types.Block, i int, db ethutil.Database) *types.Block {
+	addr := ethutil.LeftPadBytes([]byte{byte(i)}, 20)
+	block := newBlockFromParent(addr, parent)
+	state := state.New(block.Root(), db)
+	cbase := state.GetOrNewStateObject(addr)
+	cbase.SetGasPool(CalcGasLimit(parent, block))
+	cbase.AddBalance(BlockReward)
+	state.Update(ethutil.Big0)
+	block.SetRoot(state.Root())
+	return block
+}
+
+// Make a chain with real blocks
+// Runs ProcessWithParent to get proper state roots
+func makeChain(bman *BlockProcessor, parent *types.Block, max int, db ethutil.Database) types.Blocks {
+	bman.bc.currentBlock = parent
+	blocks := make(types.Blocks, max)
+	for i := 0; i < max; i++ {
+		block := makeBlock(bman, parent, i, db)
+		td, err := bman.processWithParent(block, parent)
+		if err != nil {
+			fmt.Println("process with parent failed", err)
+			panic(err)
+		}
+		block.Td = td
+		blocks[i] = block
+		parent = block
+		fmt.Printf("New Block: %x\n", block.Hash())
+	}
+	fmt.Println("Done making chain")
+	return blocks
+}
+
+// Create a new chain manager starting from given block
+// Effectively a fork factory
+func newChainManager(block *types.Block, eventMux *event.TypeMux, db ethutil.Database) *ChainManager {
+	bc := &ChainManager{db: db, genesisBlock: GenesisBlock(db), eventMux: eventMux}
+	if block == nil {
+		bc.Reset()
+	} else {
+		bc.currentBlock = block
+		bc.td = block.Td
+	}
+	return bc
+}
+
+// block processor with fake pow
+func newBlockProcessor(db ethutil.Database, txpool *TxPool, cman *ChainManager, eventMux *event.TypeMux) *BlockProcessor {
+	bman := NewBlockProcessor(db, txpool, newChainManager(nil, eventMux, db), eventMux)
+	bman.Pow = FakePow{}
+	return bman
+}
+
+// Make a new canonical chain by running InsertChain
+// on result of makeChain
+func newCanonical(n int, db ethutil.Database) (*BlockProcessor, error) {
+	eventMux := &event.TypeMux{}
+	txpool := NewTxPool(eventMux)
+
+	bman := newBlockProcessor(db, txpool, newChainManager(nil, eventMux, db), eventMux)
+	bman.bc.SetProcessor(bman)
+	parent := bman.bc.CurrentBlock()
+	if n == 0 {
+		return bman, nil
+	}
+	lchain := makeChain(bman, parent, n, db)
+	bman.bc.InsertChain(lchain)
+	return bman, nil
+}
-- 
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