Thrift Package for Go
API Documentation: http://go.pkgdoc.org/github.com/samuel/go-thrift
License
3-clause BSD. See LICENSE file.
Overview
So why another thrift package? While the existing one (thrift4go) works well, my philosophy is that interfaces should match the language. Most Thrift libraries try to match the API of the original which makes them awkward to use in other languages.
As an example, Go already has the idea of a thrift transport in the ReadWriteCloser interfaces.
Another design decision was to keep the generated code as terse as possible. The generator only creates a struct and the encoding/decoding is done through reflection. Annotations are used to set thrift ID for a field and options such as 'required'.
Example struct:
type User struct {
Id int64 `thrift:"1,required"`
Name string `thrift:"2"`
PostCount int32 `thrift:"3,keepempty"`
Flags []string `thrift:"4"`
SomeSet []string `thrift:"5,set"`
}
Types
Most types map directly to the native Go types, but there are some quirks and limitations.
-
Go supports a more limited set of types for map keys than Thrift
-
To use a set define the field as []type and provide a tag of "set":
StringSet []string `thrift:"1,set"`
-
Unsigned types aren't supported. Thrift only has signed types. Could encode/decode unsigned types as their signed counterparts, but I decided against that for now.
-
[]byte get encoded/decoded as a string because the Thrift binary type is the same as string on the wire.
RPC
The standard Go net/rpc package is used to provide RPC. Although, one incompatibility is the net/rpc's use of ServiceName.Method for naming RPC methods. To get around this the Thrift ServerCodec prefixes method names with "Thrift".
Transport
There are no specific transport "classes" as there are in most Thrift
libraries. Instead, the standard io.ReadWriteCloser
is used as the
interface. If the value also implements the thrift.Flusher interface
then Flush() error
is called after protocol.WriteMessageEnd
.
Framed transport is supported by wrapping a value implementing
io.ReadWriteCloser
with thrift.NewFramedReadWriteCloser(value)
Parser & Code Generator
The "parser" subdirectory contains a Thrift IDL parser, and "generator" contains a Go code generator. It could be extended to include other languages in the future.
How to use the generator:
$ go install github.com/samuel/go-thrift/generator
$ generator --help
Usage of parsimony: [options] inputfile outputfile
-go.binarystring=false: Always use string for binary instead of []byte
-go.json.enumname=false: For JSON marshal enums by name instead of value
-go.packagename="": Override the package name
-go.pointers=false: Make all fields pointers
$ mkdir $GOPATH/src/cassandra
$ generator cassandra.thrift $GOPATH/cassandra/thrift.go
# Then can import "cassandra"