763f939f47
This commit implements a dual state approach. The dual state approach separates public and private state by making the core vm environment context aware. Although not currently implemented it will need to prohibit value transfers and it must initialise all transactions from accounts on the public state. This means that sending transactions increments the account nonce on the public state and contract addresses are derived from the public state when initialised by a transaction. For obvious reasons, contract created by private contracts are still derived from public state. This is required in order to have consensus over the public state at all times as non-private participants would still process the transaction on the public state even though private payload can not be decrypted. This means that participants of a private group must do the same in order to have public consensus. However the creation of the contract and interaction still occurs on the private state. It implements support for the following calling model: S: sender, (X): private, X: public, ->: direction, [ ]: read only mode 1. S -> A -> B 2. S -> (A) -> (B) 3. S -> (A) -> [ B -> C ] It does not support 1. (S) -> A 2. (S) -> (A) 3. S -> (A) -> B Implemented "read only" mode for the EVM. Read only mode is checked during any opcode that could potentially modify the state. If such an opcode is encountered during "read only", it throws an exception. The EVM is flagged "read only" when a private contract calls in to public state. |
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.. | ||
compiler | ||
httpclient | ||
math | ||
number | ||
registrar | ||
.gitignore | ||
.travis.yml | ||
README.md | ||
big.go | ||
big_test.go | ||
bytes.go | ||
bytes_test.go | ||
debug.go | ||
format.go | ||
icap.go | ||
icap_test.go | ||
list.go | ||
main_test.go | ||
path.go | ||
size.go | ||
size_test.go | ||
test_utils.go | ||
types.go | ||
types_template.go | ||
types_test.go |
README.md
common
The common package contains the ethereum utility library.
Installation
As a subdirectory the main go-ethereum repository, you get it with
go get github.com/ethereum/go-ethereum
.
Usage
RLP (Recursive Linear Prefix) Encoding
RLP Encoding is an encoding scheme used by the Ethereum project. It encodes any native value or list to a string.
More in depth information about the encoding scheme see the Wiki article.
rlp := common.Encode("doge")
fmt.Printf("%q\n", rlp) // => "\0x83dog"
rlp = common.Encode([]interface{}{"dog", "cat"})
fmt.Printf("%q\n", rlp) // => "\0xc8\0x83dog\0x83cat"
decoded := common.Decode(rlp)
fmt.Println(decoded) // => ["dog" "cat"]
Patricia Trie
Patricie Tree is a merkle trie used by the Ethereum project.
More in depth information about the (modified) Patricia Trie can be found on the Wiki.
The patricia trie uses a db as backend and could be anything as long as
it satisfies the Database interface found in common/db.go
.
db := NewDatabase()
// db, root
trie := common.NewTrie(db, "")
trie.Put("puppy", "dog")
trie.Put("horse", "stallion")
trie.Put("do", "verb")
trie.Put("doge", "coin")
// Look up the key "do" in the trie
out := trie.Get("do")
fmt.Println(out) // => verb
trie.Delete("puppy")
The patricia trie, in combination with RLP, provides a robust, cryptographically authenticated data structure that can be used to store all (key, value) bindings.
// ... Create db/trie
// Note that RLP uses interface slices as list
value := common.Encode([]interface{}{"one", 2, "three", []interface{}{42}})
// Store the RLP encoded value of the list
trie.Put("mykey", value)
Value
Value is a Generic Value which is used in combination with RLP data or
([])interface{}
structures. It may serve as a bridge between RLP data
and actual real values and takes care of all the type checking and
casting. Unlike Go's reflect.Value
it does not panic if it's unable to
cast to the requested value. It simple returns the base value of that
type (e.g. Slice()
returns []interface{}, Uint()
return 0, etc).
Creating a new Value
NewEmptyValue()
returns a new *Value with it's initial value set to a
[]interface{}
AppendList()
appends a list to the current value.
Append(v)
appends the value (v) to the current value/list.
val := common.NewEmptyValue().Append(1).Append("2")
val.AppendList().Append(3)
Retrieving values
Get(i)
returns the i
item in the list.
Uint()
returns the value as an unsigned int64.
Slice()
returns the value as a interface slice.
Str()
returns the value as a string.
Bytes()
returns the value as a byte slice.
Len()
assumes current to be a slice and returns its length.
Byte()
returns the value as a single byte.
val := common.NewValue([]interface{}{1,"2",[]interface{}{3}})
val.Get(0).Uint() // => 1
val.Get(1).Str() // => "2"
s := val.Get(2) // => Value([]interface{}{3})
s.Get(0).Uint() // => 3
Decoding
Decoding streams of RLP data is simplified
val := common.NewValueFromBytes(rlpData)
val.Get(0).Uint()
Encoding
Encoding from Value to RLP is done with the Encode
method. The
underlying value can be anything RLP can encode (int, str, lists, bytes)
val := common.NewValue([]interface{}{1,"2",[]interface{}{3}})
rlp := val.Encode()
// Store the rlp data
Store(rlp)