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package sarama
import (
"bytes"
"encoding/binary"
"fmt"
"io"
"net"
"reflect"
"strconv"
"sync"
"time"
"github.com/davecgh/go-spew/spew"
)
const (
expectationTimeout = 500 * time.Millisecond
)
type requestHandlerFunc func(req *request) (res encoder)
// RequestNotifierFunc is invoked when a mock broker processes a request successfully
// and will provides the number of bytes read and written.
type RequestNotifierFunc func(bytesRead, bytesWritten int)
// MockBroker is a mock Kafka broker that is used in unit tests. It is exposed
// to facilitate testing of higher level or specialized consumers and producers
// built on top of Sarama. Note that it does not 'mimic' the Kafka API protocol,
// but rather provides a facility to do that. It takes care of the TCP
// transport, request unmarshaling, response marshaling, and makes it the test
// writer responsibility to program correct according to the Kafka API protocol
// MockBroker behaviour.
//
// MockBroker is implemented as a TCP server listening on a kernel-selected
// localhost port that can accept many connections. It reads Kafka requests
// from that connection and returns responses programmed by the SetHandlerByMap
// function. If a MockBroker receives a request that it has no programmed
// response for, then it returns nothing and the request times out.
//
// A set of MockRequest builders to define mappings used by MockBroker is
// provided by Sarama. But users can develop MockRequests of their own and use
// them along with or instead of the standard ones.
//
// When running tests with MockBroker it is strongly recommended to specify
// a timeout to `go test` so that if the broker hangs waiting for a response,
// the test panics.
//
// It is not necessary to prefix message length or correlation ID to your
// response bytes, the server does that automatically as a convenience.
type MockBroker struct {
brokerID int32
port int32
closing chan none
stopper chan none
expectations chan encoder
listener net.Listener
t TestReporter
latency time.Duration
handler requestHandlerFunc
notifier RequestNotifierFunc
history []RequestResponse
lock sync.Mutex
}
// RequestResponse represents a Request/Response pair processed by MockBroker.
type RequestResponse struct {
Request protocolBody
Response encoder
}
// SetLatency makes broker pause for the specified period every time before
// replying.
func (b *MockBroker) SetLatency(latency time.Duration) {
b.latency = latency
}
// SetHandlerByMap defines mapping of Request types to MockResponses. When a
// request is received by the broker, it looks up the request type in the map
// and uses the found MockResponse instance to generate an appropriate reply.
// If the request type is not found in the map then nothing is sent.
func (b *MockBroker) SetHandlerByMap(handlerMap map[string]MockResponse) {
b.setHandler(func(req *request) (res encoder) {
reqTypeName := reflect.TypeOf(req.body).Elem().Name()
mockResponse := handlerMap[reqTypeName]
if mockResponse == nil {
return nil
}
return mockResponse.For(req.body)
})
}
// SetNotifier set a function that will get invoked whenever a request has been
// processed successfully and will provide the number of bytes read and written
func (b *MockBroker) SetNotifier(notifier RequestNotifierFunc) {
b.lock.Lock()
b.notifier = notifier
b.lock.Unlock()
}
// BrokerID returns broker ID assigned to the broker.
func (b *MockBroker) BrokerID() int32 {
return b.brokerID
}
// History returns a slice of RequestResponse pairs in the order they were
// processed by the broker. Note that in case of multiple connections to the
// broker the order expected by a test can be different from the order recorded
// in the history, unless some synchronization is implemented in the test.
func (b *MockBroker) History() []RequestResponse {
b.lock.Lock()
history := make([]RequestResponse, len(b.history))
copy(history, b.history)
b.lock.Unlock()
return history
}
// Port returns the TCP port number the broker is listening for requests on.
func (b *MockBroker) Port() int32 {
return b.port
}
// Addr returns the broker connection string in the form "<address>:<port>".
func (b *MockBroker) Addr() string {
return b.listener.Addr().String()
}
// Close terminates the broker blocking until it stops internal goroutines and
// releases all resources.
func (b *MockBroker) Close() {
close(b.expectations)
if len(b.expectations) > 0 {
buf := bytes.NewBufferString(fmt.Sprintf("mockbroker/%d: not all expectations were satisfied! Still waiting on:\n", b.BrokerID()))
for e := range b.expectations {
_, _ = buf.WriteString(spew.Sdump(e))
}
b.t.Error(buf.String())
}
close(b.closing)
<-b.stopper
}
// setHandler sets the specified function as the request handler. Whenever
// a mock broker reads a request from the wire it passes the request to the
// function and sends back whatever the handler function returns.
func (b *MockBroker) setHandler(handler requestHandlerFunc) {
b.lock.Lock()
b.handler = handler
b.lock.Unlock()
}
func (b *MockBroker) serverLoop() {
defer close(b.stopper)
var err error
var conn net.Conn
go func() {
<-b.closing
err := b.listener.Close()
if err != nil {
b.t.Error(err)
}
}()
wg := &sync.WaitGroup{}
i := 0
for conn, err = b.listener.Accept(); err == nil; conn, err = b.listener.Accept() {
wg.Add(1)
go b.handleRequests(conn, i, wg)
i++
}
wg.Wait()
Logger.Printf("*** mockbroker/%d: listener closed, err=%v", b.BrokerID(), err)
}
func (b *MockBroker) handleRequests(conn net.Conn, idx int, wg *sync.WaitGroup) {
defer wg.Done()
defer func() {
_ = conn.Close()
}()
Logger.Printf("*** mockbroker/%d/%d: connection opened", b.BrokerID(), idx)
var err error
abort := make(chan none)
defer close(abort)
go func() {
select {
case <-b.closing:
_ = conn.Close()
case <-abort:
}
}()
resHeader := make([]byte, 8)
for {
req, bytesRead, err := decodeRequest(conn)
if err != nil {
Logger.Printf("*** mockbroker/%d/%d: invalid request: err=%+v, %+v", b.brokerID, idx, err, spew.Sdump(req))
b.serverError(err)
break
}
if b.latency > 0 {
time.Sleep(b.latency)
}
b.lock.Lock()
res := b.handler(req)
b.history = append(b.history, RequestResponse{req.body, res})
b.lock.Unlock()
if res == nil {
Logger.Printf("*** mockbroker/%d/%d: ignored %v", b.brokerID, idx, spew.Sdump(req))
continue
}
Logger.Printf("*** mockbroker/%d/%d: served %v -> %v", b.brokerID, idx, req, res)
encodedRes, err := encode(res, nil)
if err != nil {
b.serverError(err)
break
}
if len(encodedRes) == 0 {
b.lock.Lock()
if b.notifier != nil {
b.notifier(bytesRead, 0)
}
b.lock.Unlock()
continue
}
binary.BigEndian.PutUint32(resHeader, uint32(len(encodedRes)+4))
binary.BigEndian.PutUint32(resHeader[4:], uint32(req.correlationID))
if _, err = conn.Write(resHeader); err != nil {
b.serverError(err)
break
}
if _, err = conn.Write(encodedRes); err != nil {
b.serverError(err)
break
}
b.lock.Lock()
if b.notifier != nil {
b.notifier(bytesRead, len(resHeader)+len(encodedRes))
}
b.lock.Unlock()
}
Logger.Printf("*** mockbroker/%d/%d: connection closed, err=%v", b.BrokerID(), idx, err)
}
func (b *MockBroker) defaultRequestHandler(req *request) (res encoder) {
select {
case res, ok := <-b.expectations:
if !ok {
return nil
}
return res
case <-time.After(expectationTimeout):
return nil
}
}
func (b *MockBroker) serverError(err error) {
isConnectionClosedError := false
if _, ok := err.(*net.OpError); ok {
isConnectionClosedError = true
} else if err == io.EOF {
isConnectionClosedError = true
} else if err.Error() == "use of closed network connection" {
isConnectionClosedError = true
}
if isConnectionClosedError {
return
}
b.t.Errorf(err.Error())
}
// NewMockBroker launches a fake Kafka broker. It takes a TestReporter as provided by the
// test framework and a channel of responses to use. If an error occurs it is
// simply logged to the TestReporter and the broker exits.
func NewMockBroker(t TestReporter, brokerID int32) *MockBroker {
return NewMockBrokerAddr(t, brokerID, "localhost:0")
}
// NewMockBrokerAddr behaves like newMockBroker but listens on the address you give
// it rather than just some ephemeral port.
func NewMockBrokerAddr(t TestReporter, brokerID int32, addr string) *MockBroker {
listener, err := net.Listen("tcp", addr)
if err != nil {
t.Fatal(err)
}
return NewMockBrokerListener(t, brokerID, listener)
}
// NewMockBrokerListener behaves like newMockBrokerAddr but accepts connections on the listener specified.
func NewMockBrokerListener(t TestReporter, brokerID int32, listener net.Listener) *MockBroker {
var err error
broker := &MockBroker{
closing: make(chan none),
stopper: make(chan none),
t: t,
brokerID: brokerID,
expectations: make(chan encoder, 512),
listener: listener,
}
broker.handler = broker.defaultRequestHandler
Logger.Printf("*** mockbroker/%d listening on %s\n", brokerID, broker.listener.Addr().String())
_, portStr, err := net.SplitHostPort(broker.listener.Addr().String())
if err != nil {
t.Fatal(err)
}
tmp, err := strconv.ParseInt(portStr, 10, 32)
if err != nil {
t.Fatal(err)
}
broker.port = int32(tmp)
go broker.serverLoop()
return broker
}
func (b *MockBroker) Returns(e encoder) {
b.expectations <- e
}
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