Added support for Haystack tracing

vendor/github.com/ExpediaDotCom/haystack-client-go/remote_client.go

@@ -0,0 +1,165 @@
+/*
+ *  Copyright 2018 Expedia Group.
+ *
+ *     Licensed 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.
+ *
+ */
+
+package haystack
+
+import (
+	"bytes"
+	"fmt"
+	"io/ioutil"
+	"net/http"
+	"time"
+
+	"github.com/golang/protobuf/proto"
+	context "golang.org/x/net/context"
+	grpc "google.golang.org/grpc"
+)
+
+/*RemoteClient remote client*/
+type RemoteClient interface {
+	Send(span *Span)
+	Close() error
+	SetLogger(logger Logger)
+}
+
+/*GrpcClient grpc client*/
+type GrpcClient struct {
+	conn    *grpc.ClientConn
+	client  SpanAgentClient
+	timeout time.Duration
+	logger  Logger
+}
+
+/*NewGrpcClient returns a new grpc client*/
+func NewGrpcClient(host string, port int, timeout time.Duration) *GrpcClient {
+	targetHost := fmt.Sprintf("%s:%d", host, port)
+	conn, err := grpc.Dial(targetHost, grpc.WithInsecure())
+
+	if err != nil {
+		panic(fmt.Sprintf("fail to connect to agent with error: %v", err))
+	}
+
+	return &GrpcClient{
+		conn:    conn,
+		client:  NewSpanAgentClient(conn),
+		timeout: timeout,
+	}
+}
+
+/*Send a proto span to grpc server*/
+func (c *GrpcClient) Send(span *Span) {
+	ctx, cancel := context.WithTimeout(context.Background(), c.timeout)
+	defer cancel()
+
+	result, err := c.client.Dispatch(ctx, span)
+
+	if err != nil {
+		c.logger.Error("Fail to dispatch to haystack-agent with error %v", err)
+	} else if result.GetCode() != DispatchResult_SUCCESS {
+		c.logger.Error(fmt.Sprintf("Fail to dispatch to haystack-agent with error code: %d, message :%s", result.GetCode(), result.GetErrorMessage()))
+	} else {
+		c.logger.Debug(fmt.Sprintf("span [%v] has been successfully dispatched to haystack", span))
+	}
+}
+
+/*Close the grpc client*/
+func (c *GrpcClient) Close() error {
+	return c.conn.Close()
+}
+
+/*SetLogger sets the logger*/
+func (c *GrpcClient) SetLogger(logger Logger) {
+	c.logger = logger
+}
+
+/*HTTPClient a http client*/
+type HTTPClient struct {
+	url     string
+	headers map[string]string
+	client  *http.Client
+	logger  Logger
+}
+
+/*NewHTTPClient returns a new http client*/
+func NewHTTPClient(url string, headers map[string]string, timeout time.Duration) *HTTPClient {
+	httpClient := &http.Client{
+		Timeout: timeout,
+	}
+
+	return &HTTPClient{
+		url:     url,
+		headers: headers,
+		client:  httpClient,
+	}
+}
+
+/*Send a proto span to http server*/
+func (c *HTTPClient) Send(span *Span) {
+	serializedBytes, marshalErr := proto.Marshal(span)
+
+	if marshalErr != nil {
+		c.logger.Error("Fail to serialize the span to proto bytes, error=%v", marshalErr)
+		return
+	}
+
+	postRequest, requestErr := http.NewRequest(http.MethodPost, c.url, bytes.NewReader(serializedBytes))
+	if requestErr != nil {
+		c.logger.Error("Fail to create request for posting span to haystack server, error=%v", requestErr)
+		return
+	}
+
+	if c.headers != nil {
+		for k, v := range c.headers {
+			postRequest.Header.Add(k, v)
+		}
+	}
+
+	resp, err := c.client.Do(postRequest)
+
+	if err != nil {
+		c.logger.Error("Fail to dispatch to haystack http server, error=%v", err)
+	}
+
+	defer func() {
+		closeErr := resp.Body.Close()
+		if closeErr != nil {
+			/* do nothing */
+		}
+	}()
+
+	respBytes, respErr := ioutil.ReadAll(resp.Body)
+	if respErr != nil {
+		c.logger.Error("Fail to read the http response from haystack server, error=%v", respErr)
+		return
+	}
+
+	if resp.StatusCode < 200 || resp.StatusCode >= 300 {
+		c.logger.Error("Fail to dispatch the span to haystack http server with statusCode=%d , payload=%s", resp.StatusCode, string(respBytes))
+	} else {
+		c.logger.Debug(fmt.Sprintf("span [%v] has been successfully dispatched to haystack, response=%s", span, string(respBytes)))
+	}
+}
+
+/*Close the http client*/
+func (c *HTTPClient) Close() error {
+	return nil
+}
+
+/*SetLogger sets the logger*/
+func (c *HTTPClient) SetLogger(logger Logger) {
+	c.logger = logger
+}