289b30715d
This commit converts the dependency management from Godeps to the vendor folder, also switching the tool from godep to trash. Since the upstream tool lacks a few features proposed via a few PRs, until those PRs are merged in (if), use github.com/karalabe/trash. You can update dependencies via trash --update. All dependencies have been updated to their latest version. Parts of the build system are reworked to drop old notions of Godeps and invocation of the go vet command so that it doesn't run against the vendor folder, as that will just blow up during vetting. The conversion drops OpenCL (and hence GPU mining support) from ethash and our codebase. The short reasoning is that there's noone to maintain and having opencl libs in our deps messes up builds as go install ./... tries to build them, failing with unsatisfied link errors for the C OpenCL deps. golang.org/x/net/context is not vendored in. We expect it to be fetched by the user (i.e. using go get). To keep ci.go builds reproducible the package is "vendored" in build/_vendor. |
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.. | ||
compiler | ||
httpclient | ||
math | ||
number | ||
registrar | ||
.gitignore | ||
.travis.yml | ||
big_test.go | ||
big.go | ||
bytes_test.go | ||
bytes.go | ||
debug.go | ||
format.go | ||
icap_test.go | ||
icap.go | ||
list.go | ||
main_test.go | ||
path.go | ||
README.md | ||
size_test.go | ||
size.go | ||
test_utils.go | ||
types_template.go | ||
types_test.go | ||
types.go |
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)