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progress on a streaming interface

This commit is contained in:
Vincent Batts 2015-03-25 17:28:17 -04:00
parent 949cec0dce
commit fd362c6aa5
3 changed files with 74 additions and 18 deletions

22
node.go
View file

@ -1,23 +1,22 @@
package merkle
import (
"crypto"
_ "crypto/sha1" // to satisfy our DefaultHash
"crypto/sha1"
"fmt"
"hash"
)
var (
// DefaultHash is for checksum of blocks and nodes
DefaultHash = crypto.SHA1
// DefaultHashMaker is for checksum of blocks and nodes
DefaultHashMaker = func() hash.Hash { return sha1.New() }
)
// HashMaker produces a new has for use in making checksums
type HashMaker func() hash.Hash
// NewNode returns a new Node with the DefaultHash for checksums
// NewNode returns a new Node with the DefaultHashMaker for checksums
func NewNode() *Node {
return NewNodeHash(DefaultHash.New)
return NewNodeHash(DefaultHashMaker)
}
// NewNodeHash returns a new Node using the provided crypto.Hash for checksums
@ -25,13 +24,22 @@ func NewNodeHash(h HashMaker) *Node {
return &Node{hash: h}
}
// NewNodeHashBlock returns a new Node using the provided crypto.Hash, and calculates the block's checksum
func NewNodeHashBlock(h HashMaker, b []byte) *Node {
n := &Node{hash: h}
h1 := n.hash()
h1.Write(b)
n.checksum = h1.Sum(nil)
return n
}
// Node is a fundamental part of the tree.
type Node struct {
hash HashMaker
checksum []byte
Parent, Left, Right *Node
pos int // XXX maybe keep their order when it is a direct block's hash
//pos int // XXX maybe keep their order when it is a direct block's hash
}
// IsLeaf indicates this node is for specific block (and has no children)

View file

@ -9,7 +9,7 @@ import (
func TestNodeSums(t *testing.T) {
var (
nodes []*Node
h = DefaultHash.New()
h = DefaultHashMaker()
words = `Who were expelled from the academy for crazy & publishing obscene odes on the windows of the skull`
expectedChecksum = "819fe8fed7a46900bd0613344c5ba2be336c74db"
)
@ -19,7 +19,7 @@ func TestNodeSums(t *testing.T) {
t.Errorf("on word %q, encountered %s", word, err)
}
sum := h.Sum(nil)
nodes = append(nodes, &Node{checksum: sum, hash: DefaultHash.New})
nodes = append(nodes, &Node{checksum: sum, hash: DefaultHashMaker})
}
newNodes := nodes

View file

@ -1,14 +1,18 @@
package merkle
import "hash"
import (
"hash"
"log"
)
// NewHash provides a hash.Hash to generate a merkle.Tree checksum, given a
// HashMaker for the checksums of the blocks written and the blockSize of each
// block per node in the tree.
func NewHash(hm HashMaker, merkleBlockSize int) hash.Hash {
func NewHash(hm HashMaker, merkleBlockLength int) hash.Hash {
mh := new(merkleHash)
mh.blockSize = merkleBlockSize
mh.blockSize = merkleBlockLength
mh.hm = hm
mh.tree = &Tree{Nodes: []*Node{}, BlockLength: merkleBlockLength}
return mh
}
@ -18,9 +22,11 @@ func NewHash(hm HashMaker, merkleBlockSize int) hash.Hash {
// TODO satisfy the hash.Hash interface
type merkleHash struct {
blockSize int
tree Tree
hm HashMaker
blockSize int
tree *Tree
hm HashMaker
lastBlock []byte // as needed, for Sum()
partialLastBlock bool
}
// XXX this will be tricky, as the last block can be less than the BlockSize.
@ -32,15 +38,57 @@ type merkleHash struct {
//
// if that last block was complete, then no worries. start the next node.
func (mh *merkleHash) Sum(b []byte) []byte {
return nil
// TODO check if len(mh.lastBlock) < blockSize
sum, err := mh.tree.Root().Checksum()
if err != nil {
log.Println(err)
}
return sum
}
func (mh *merkleHash) Write(b []byte) (int, error) {
return 0, nil
// basically we need to:
// * chunk these writes into blockSize
// * create Node of the sum
// * add the Node to the tree
// * stash remainder in the mh.lastBlock
var (
curBlock = make([]byte, mh.blockSize)
numBytes int = 0
numWritten int
)
if mh.lastBlock != nil && len(mh.lastBlock) > 0 {
numBytes = copy(curBlock, mh.lastBlock)
// not adding to numWritten, since these blocks were accounted for in a
// prior Write()
}
if numBytes > 0 {
copy(curBlock, b[:(mh.blockSize-numBytes)])
numWritten += (mh.blockSize - numBytes)
// TODO Node for curBlock
n := NewNodeHashBlock(mh.hm, curBlock)
_ = n
}
numBytes = len(b) - numBytes
for i := 0; i < numBytes/mh.blockSize; i++ {
// TODO Node for curBlock
}
// TODO stash (numBytes % mh.blockSize) in mh.lastBlock
// TODO if len(mh.lastBlock) < blockSize, then set that before returning
return numWritten, nil
}
func (mh *merkleHash) Reset() {
mh.Tree = Tree{}
mh.tree = &Tree{}
mh.lastBlock = nil
}
// likely not the best to pass this through and not use our own node block
// size, but let's revisit this.
func (mh *merkleHash) BlockSize() int { return mh.hm().BlockSize() }
func (mh *merkleHash) Size() int { return mh.hm().Size() }