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forked from openzipkin-contrib/zipkin-go-opentracing
/
httpclient.go
82 lines (68 loc) · 1.96 KB
/
httpclient.go
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// +build go1.7
package svc2
import (
"context"
"fmt"
"io/ioutil"
"net/http"
"strconv"
opentracing "github.com/opentracing/opentracing-go"
"github.com/openzipkin-contrib/zipkin-go-opentracing/examples/middleware"
)
// client is our actual client implementation
type client struct {
baseURL string
httpClient *http.Client
tracer opentracing.Tracer
traceRequest middleware.RequestFunc
}
// Sum implements our Service interface.
func (c *client) Sum(ctx context.Context, a int64, b int64) (int64, error) {
// create new span using span found in context as parent (if none is found,
// our span becomes the trace root).
span, ctx := opentracing.StartSpanFromContext(ctx, "Sum")
defer span.Finish()
// assemble URL query
url := fmt.Sprintf("%s/sum/?a=%d&b=%d", c.baseURL, a, b)
// create the HTTP request
req, err := http.NewRequest("GET", url, nil)
if err != nil {
return 0, err
}
// use our middleware to propagate our trace
req = c.traceRequest(req.WithContext(ctx))
// execute the HTTP request
resp, err := c.httpClient.Do(req)
if err != nil {
// annotate our span with the error condition
span.SetTag("error", err.Error())
return 0, err
}
defer resp.Body.Close()
// read the http response body
data, err := ioutil.ReadAll(resp.Body)
if err != nil {
// annotate our span with the error condition
span.SetTag("error", err.Error())
return 0, err
}
// convert html response to expected result type (int64)
result, err := strconv.ParseInt(string(data), 10, 64)
if err != nil {
// annotate our span with the error condition
span.SetTag("error", err.Error())
return 0, err
}
// return the result
return result, nil
}
// NewHTTPClient returns a new client instance to our svc2 using the HTTP
// transport.
func NewHTTPClient(tracer opentracing.Tracer, baseURL string) Service {
return &client{
baseURL: baseURL,
httpClient: &http.Client{},
tracer: tracer,
traceRequest: middleware.ToHTTPRequest(tracer),
}
}