9eaf824398
* add jaeger support, link hot container & req span * adds jaeger support now with FN_JAEGER_URL, there's a simple tutorial in the operating/metrics.md file now and it's pretty easy to get up and running. * links a hot request span to a hot container span. when we change this to sample at a lower ratio we'll need to finagle the hot container span to always sample or something, otherwise we'll hide that info. at least, since we're sampling at 100% for now if this is flipped on, can see freeze/unfreeze etc. if they hit. this is useful for debugging. note that zipkin's exporter does not follow the link at all, hence jaeger... and they're backed by the Cloud Empire now (CNCF) so we'll probably use it anyway. * vendor: add thrift for jaeger
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
In following Go conventions, we recommend you use the 'go' tool to install Thrift for go.
$ go get git.apache.org/thrift.git/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"`
}