// Just checking behavior of the context package
func TestSanity(t *testing.T) {
Logger.Level = logrus.InfoLevel
levels := 10
root, cancel := context.WithDeadline(context.Background(), time.Time{})
defer cancel()
var ctxFunc func(parent context.Context, level int) context.Context
ctxFunc = func(parent context.Context, level int) context.Context {
if level == levels {
return parent
}
child, cancel := context.WithDeadline(parent, time.Now().Add(time.Hour))
defer cancel()
return ctxFunc(child, level+1)
}
child := ctxFunc(root, 0)
if !assert.Error(t, child.Err()) {
t.FailNow()
}
err := root.Err()
if !assert.Error(t, err) {
return
}
}
// DeadlineHandler returns a Handler which adds a deadline to the context.
//
// Child handlers are responsible for obeying the context deadline and returning
// an appropriate error (or not) response in case of timeout.
func DeadlineHandler(deadline time.Time) func(http.Handler) http.Handler {
return func(h http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, req *http.Request) {
ctx, cancel := context.WithDeadline(req.Context(), deadline)
req = req.WithContext(ctx)
defer cancel()
h.ServeHTTP(w, req)
})
}
}
// Do a lookup for a single name, which must be rooted
// (otherwise answer will not find the answers).
func tryOneName(ctx context.Context, cfg *dnsConfig, name string, qtype uint16) (string, []dnsRR, error) {
if len(cfg.servers) == 0 {
return "", nil, &DNSError{Err: "no DNS servers", Name: name}
}
deadline := time.Now().Add(cfg.timeout)
if old, ok := ctx.Deadline(); !ok || deadline.Before(old) {
var cancel context.CancelFunc
ctx, cancel = context.WithDeadline(ctx, deadline)
defer cancel()
}
var lastErr error
for i := 0; i < cfg.attempts; i++ {
for _, server := range cfg.servers {
msg, err := exchange(ctx, server, name, qtype)
if err != nil {
lastErr = &DNSError{
Err: err.Error(),
Name: name,
Server: server,
}
if nerr, ok := err.(Error); ok && nerr.Timeout() {
lastErr.(*DNSError).IsTimeout = true
}
continue
}
// libresolv continues to the next server when it receives
// an invalid referral response. See golang.org/issue/15434.
if msg.rcode == dnsRcodeSuccess && !msg.authoritative && !msg.recursion_available && len(msg.answer) == 0 && len(msg.extra) == 0 {
lastErr = &DNSError{Err: "lame referral", Name: name, Server: server}
continue
}
cname, rrs, err := answer(name, server, msg, qtype)
// If answer errored for rcodes dnsRcodeSuccess or dnsRcodeNameError,
// it means the response in msg was not useful and trying another
// server probably won't help. Return now in those cases.
// TODO: indicate this in a more obvious way, such as a field on DNSError?
if err == nil || msg.rcode == dnsRcodeSuccess || msg.rcode == dnsRcodeNameError {
return cname, rrs, err
}
lastErr = err
}
}
return "", nil, lastErr
}
func (s *Stream) waitForData(ctx context.Context) error {
if !s.rDeadline.IsZero() {
dctx, cancel := context.WithDeadline(ctx, s.rDeadline)
defer cancel()
ctx = dctx
}
select {
case read, ok := <-s.dataIn:
if !ok {
return io.EOF
}
s.extra = read
s.exbuf = read
return nil
case <-ctx.Done():
return ctx.Err()
}
}
// This example passes a context with a arbitrary deadline to tell a blocking
// function that it should abandon its work as soon as it gets to it.
func ExampleWithDeadline() {
d := time.Now().Add(50 * time.Millisecond)
ctx, cancel := context.WithDeadline(context.Background(), d)
// Even though ctx will be expired, it is good practice to call its
// cancelation function in any case. Failure to do so may keep the
// context and its parent alive longer than necessary.
defer cancel()
select {
case <-time.After(1 * time.Second):
fmt.Println("overslept")
case <-ctx.Done():
fmt.Println(ctx.Err())
}
// Output:
// context deadline exceeded
}
// dialSerial connects to a list of addresses in sequence, returning
// either the first successful connection, or the first error.
func dialSerial(ctx context.Context, dp *dialParam, ras addrList) (Conn, error) {
var firstErr error // The error from the first address is most relevant.
for i, ra := range ras {
select {
case <-ctx.Done():
return nil, &OpError{Op: "dial", Net: dp.network, Source: dp.LocalAddr, Addr: ra, Err: mapErr(ctx.Err())}
default:
}
deadline, _ := ctx.Deadline()
partialDeadline, err := partialDeadline(time.Now(), deadline, len(ras)-i)
if err != nil {
// Ran out of time.
if firstErr == nil {
firstErr = &OpError{Op: "dial", Net: dp.network, Source: dp.LocalAddr, Addr: ra, Err: err}
}
break
}
dialCtx := ctx
if partialDeadline.Before(deadline) {
var cancel context.CancelFunc
dialCtx, cancel = context.WithDeadline(ctx, partialDeadline)
defer cancel()
}
c, err := dialSingle(dialCtx, dp, ra)
if err == nil {
return c, nil
}
if firstErr == nil {
firstErr = err
}
}
if firstErr == nil {
firstErr = &OpError{Op: "dial", Net: dp.network, Source: nil, Addr: nil, Err: errMissingAddress}
}
return nil, firstErr
}
// exchange sends a query on the connection and hopes for a response.
func exchange(ctx context.Context, server, name string, qtype uint16, timeout time.Duration) (*dnsMsg, error) {
d := testHookDNSDialer()
out := dnsMsg{
dnsMsgHdr: dnsMsgHdr{
recursion_desired: true,
},
question: []dnsQuestion{
{name, qtype, dnsClassINET},
},
}
for _, network := range []string{"udp", "tcp"} {
// TODO(mdempsky): Refactor so defers from UDP-based
// exchanges happen before TCP-based exchange.
ctx, cancel := context.WithDeadline(ctx, time.Now().Add(timeout))
defer cancel()
c, err := d.dialDNS(ctx, network, server)
if err != nil {
return nil, err
}
defer c.Close()
if d, ok := ctx.Deadline(); ok && !d.IsZero() {
c.SetDeadline(d)
}
out.id = uint16(rand.Int()) ^ uint16(time.Now().UnixNano())
in, err := c.dnsRoundTrip(&out)
if err != nil {
return nil, mapErr(err)
}
if in.truncated { // see RFC 5966
continue
}
return in, nil
}
return nil, errors.New("no answer from DNS server")
}
// WithDeadline returns a copy of the parent context with the deadline adjusted
// to be no later than d. If the parent's deadline is already earlier than d,
// WithDeadline(parent, d) is semantically equivalent to parent. The returned
// context's Done channel is closed when the deadline expires, when the returned
// cancel function is called, or when the parent context's Done channel is
// closed, whichever happens first.
//
// Canceling this context releases resources associated with it, so code should
// call cancel as soon as the operations running in this Context complete.
func WithDeadline(parent Context, deadline time.Time) (Context, CancelFunc) {
ctx, f := context.WithDeadline(parent, deadline)
return ctx, CancelFunc(f)
}
// DialContext connects to the address on the named network using
// the provided context.
//
// The provided Context must be non-nil. If the context expires before
// the connection is complete, an error is returned. Once successfully
// connected, any expiration of the context will not affect the
// connection.
//
// See func Dial for a description of the network and address
// parameters.
func (d *Dialer) DialContext(ctx context.Context, network, address string) (Conn, error) {
if ctx == nil {
panic("nil context")
}
deadline := d.deadline(ctx, time.Now())
if !deadline.IsZero() {
if d, ok := ctx.Deadline(); !ok || deadline.Before(d) {
subCtx, cancel := context.WithDeadline(ctx, deadline)
defer cancel()
ctx = subCtx
}
}
if oldCancel := d.Cancel; oldCancel != nil {
subCtx, cancel := context.WithCancel(ctx)
defer cancel()
go func() {
select {
case <-oldCancel:
cancel()
case <-subCtx.Done():
}
}()
ctx = subCtx
}
// Shadow the nettrace (if any) during resolve so Connect events don't fire for DNS lookups.
resolveCtx := ctx
if trace, _ := ctx.Value(nettrace.TraceKey{}).(*nettrace.Trace); trace != nil {
shadow := *trace
shadow.ConnectStart = nil
shadow.ConnectDone = nil
resolveCtx = context.WithValue(resolveCtx, nettrace.TraceKey{}, &shadow)
}
addrs, err := d.resolver().resolveAddrList(resolveCtx, "dial", network, address, d.LocalAddr)
if err != nil {
return nil, &OpError{Op: "dial", Net: network, Source: nil, Addr: nil, Err: err}
}
dp := &dialParam{
Dialer: *d,
network: network,
address: address,
}
var primaries, fallbacks addrList
if d.DualStack && network == "tcp" {
primaries, fallbacks = addrs.partition(isIPv4)
} else {
primaries = addrs
}
var c Conn
if len(fallbacks) > 0 {
c, err = dialParallel(ctx, dp, primaries, fallbacks)
} else {
c, err = dialSerial(ctx, dp, primaries)
}
if err != nil {
return nil, err
}
if tc, ok := c.(*TCPConn); ok && d.KeepAlive > 0 {
setKeepAlive(tc.fd, true)
setKeepAlivePeriod(tc.fd, d.KeepAlive)
testHookSetKeepAlive()
}
return c, nil
}
{Criteria{Metric: "cpu", From: xmltime("2014-10-25T09:41:00Z"), Interval: time.Minute}, ResultSet{}},
// `until` is before the first point
{Criteria{Metric: "cpu", From: xmltime("2014-10-24T08:00:00Z"), Until: xmltime("2014-10-24T08:59:00Z"), Interval: time.Minute}, ResultSet{}},
}
for _, test := range tests {
res, err := subject.Query(context.Background(), &test.crit)
Expect(err).NotTo(HaveOccurred(), "for %+v", test.crit)
Expect(res).To(Equal(test.res), "for %+v", test.crit)
}
})
It("should query with context", func() {
subject.Set([]Point{point("cpu,a,b 1414141200 1")})
ctx, _ := context.WithDeadline(context.Background(), time.Now().Add(-time.Millisecond))
_, err := subject.Query(ctx, &Criteria{
Metric: "cpu",
From: xmltime("2014-10-24T09:00:00Z"),
Interval: time.Hour,
})
Expect(err).To(Equal(context.DeadlineExceeded))
})
It("should query points", func() {
subject.Set([]Point{
point("cpu,a,b 1414141200 1"), // 2014-10-24T09:00:00Z
point("cpu,a,c 1414141300 2"), // 2014-10-24T09:01:40Z
point("cpu,a,c 1414142000 4"), // 2014-10-24T09:13:20Z
point("cpu,b,c 1414146000 8"), // 2014-10-24T10:20:00Z
})
// WithDeadline
func WithDeadline(parent *Operation, expiration time.Time, format string, args ...interface{}) (Operation, context.CancelFunc) {
ctx, cancelFunc := context.WithDeadline(parent.Context, expiration)
op := parent.newChild(ctx, fmt.Sprintf(format, args...))
return op, cancelFunc
}
func _() {
ctx, _ := context.WithCancel() // ERROR "the cancel function returned by context.WithCancel should be called, not discarded, to avoid a context leak"
ctx, _ = context.WithTimeout() // ERROR "the cancel function returned by context.WithTimeout should be called, not discarded, to avoid a context leak"
ctx, _ = context.WithDeadline() // ERROR "the cancel function returned by context.WithDeadline should be called, not discarded, to avoid a context leak"
}
func _() {
ctx, cancel2 := context.WithDeadline() // ERROR "the cancel2 function is not used..."
} // ERROR "may be reached without using the cancel2 var defined on line 21"
func performWatchOnPrefixes(ctx context.Context, getClient getClientFunc, round int) {
runningTime := 60 * time.Second // time for which operation should be performed
noOfPrefixes := 36 // total number of prefixes which will be watched upon
watchPerPrefix := 10 // number of watchers per prefix
reqRate := 30 // put request per second
keyPrePrefix := 30 // max number of keyPrePrefixs for put operation
prefixes := stringutil.UniqueStrings(5, noOfPrefixes)
keys := stringutil.RandomStrings(10, keyPrePrefix)
roundPrefix := fmt.Sprintf("%16x", round)
var (
revision int64
wg sync.WaitGroup
gr *clientv3.GetResponse
err error
)
client := getClient()
defer client.Close()
gr, err = getKey(ctx, client, "non-existent")
if err != nil {
log.Fatalf("failed to get the initial revision: %v", err)
}
revision = gr.Header.Revision
ctxt, cancel := context.WithDeadline(ctx, time.Now().Add(runningTime))
defer cancel()
// generate and put keys in cluster
limiter := rate.NewLimiter(rate.Limit(reqRate), reqRate)
go func() {
for _, key := range keys {
for _, prefix := range prefixes {
if err = limiter.Wait(ctxt); err != nil {
return
}
if err = putKeyAtMostOnce(ctxt, client, roundPrefix+"-"+prefix+"-"+key); err != nil {
log.Fatalf("failed to put key: %v", err)
return
}
}
}
}()
ctxc, cancelc := context.WithCancel(ctx)
wcs := make([]clientv3.WatchChan, 0)
rcs := make([]*clientv3.Client, 0)
for _, prefix := range prefixes {
for j := 0; j < watchPerPrefix; j++ {
rc := getClient()
rcs = append(rcs, rc)
watchPrefix := roundPrefix + "-" + prefix
wc := rc.Watch(ctxc, watchPrefix, clientv3.WithPrefix(), clientv3.WithRev(revision))
wcs = append(wcs, wc)
wg.Add(1)
go func() {
defer wg.Done()
checkWatchResponse(wc, watchPrefix, keys)
}()
}
}
wg.Wait()
cancelc()
// verify all watch channels are closed
for e, wc := range wcs {
if _, ok := <-wc; ok {
log.Fatalf("expected wc to be closed, but received %v", e)
}
}
for _, rc := range rcs {
rc.Close()
}
if err = deletePrefix(ctx, client, roundPrefix); err != nil {
log.Fatalf("failed to clean up keys after test: %v", err)
}
}
