thrift/lib/go

Thrift Go Software Library

License

Licensed to the Apache Software Foundation (ASF) under one or more contributor license agreements. See the NOTICE file distributed with this work for additional information regarding copyright ownership. The ASF licenses this file to you under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.

Using Thrift with Go

Thrift supports Go 1.7+

In following Go conventions, we recommend you use the 'go' tool to install Thrift for go.

$ go get github.com/apache/thrift/lib/go/thrift/...

Will retrieve and install the most recent version of the package.

A note about optional fields

The thrift-to-Go compiler tries to represent thrift IDL structs as Go structs. We must be able to distinguish between optional fields that are set to their default value and optional values which are actually unset, so the generated code represents optional fields via pointers.

This is generally intuitive and works well much of the time, but Go does not have a syntax for creating a pointer to a constant in a single expression. That is, given a struct like

struct SomeIDLType {
	OptionalField *int32
}

, the following will not compile:

x := &SomeIDLType{
	OptionalField: &(3),
}

(Nor is there any other syntax that's built in to the language)

As such, we provide some helpers that do just this under lib/go/thrift/. E.g.,

x := &SomeIDLType{
	OptionalField: thrift.Int32Ptr(3),
}

And so on. The code generator also creates analogous helpers for user-defined typedefs and enums.

Adding custom tags to generated Thrift structs

You can add tags to the auto-generated thrift structs using the following format:

struct foo {
  1: required string Bar (go.tag = "some_tag:\"some_tag_value\"")
}

which will generate:

type Foo struct {
  Bar string `thrift:"bar,1,required" some_tag:"some_tag_value"`
}

A note about server handler implementations

The context object passed into the server handler function will be canceled when the client closes the connection (this is a best effort check, not a guarantee -- there's no guarantee that the context object is always canceled when client closes the connection, but when it's canceled you can always assume the client closed the connection). When implementing Go Thrift server, you can take advantage of that to abandon requests that's no longer needed:

func MyEndpoint(ctx context.Context, req *thriftRequestType) (*thriftResponseType, error) {
    ...
    if ctx.Err() == context.Canceled {
        return nil, thrift.ErrAbandonRequest
    }
    ...
}

This feature would add roughly 1 millisecond of latency overhead to the server handlers (along with roughly 2 goroutines per request). If that is unacceptable, it can be disabled by having this line early in your main function:

thrift.ServerConnectivityCheckInterval = 0

Please be advised that due to a Go runtime bug, currently if this interval is set to a value too low (for example, 1ms), it might cause excessive cpu overhead.

This feature is also only enabled on non-oneway endpoints.