unistack-org/mdns
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Allow timeout and cancellation via context.Context

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Introduce context.Context to enable cancellation in addition to the
existing timeout functionality.  To retain compatability, Timeout is
still available but will only be used if Context is not set.

We use x/net/context.Context for the moment instead of context.Context
in order to avoid creating a requirement on Go 1.7
This commit is contained in:
Martin Garton 2016-09-29 17:46:10 +01:00
parent 4725bf05ee
commit 8cfcc9a3d9
1 changed files with 14 additions and 8 deletions
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22
client.go
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@ -9,6 +9,7 @@ import (
"time"
"github.com/miekg/dns"
"golang.org/x/net/context"
"golang.org/x/net/ipv4"
"golang.org/x/net/ipv6"
)
@ -39,7 +40,8 @@ func (s *ServiceEntry) complete() bool {
type QueryParam struct {
Service string // Service to lookup
Domain string // Lookup domain, default "local"
Timeout time.Duration // Lookup timeout, default 1 second
Context context.Context // Context
Timeout time.Duration // Lookup timeout, default 1 second. Ignored if Context is provided
Interface *net.Interface // Multicast interface to use
Entries chan<- *ServiceEntry // Entries Channel
WantUnicastResponse bool // Unicast response desired, as per 5.4 in RFC
@ -79,8 +81,15 @@ func Query(params *QueryParam) error {
if params.Domain == "" {
params.Domain = "local"
}
if params.Timeout == 0 {
params.Timeout = time.Second
if params.Context == nil {
if params.Timeout == 0 {
params.Timeout = time.Second
}
params.Context, _ = context.WithTimeout(context.Background(), params.Timeout)
if err != nil {
return err
}
}
// Run the query
@ -316,9 +325,6 @@ func (c *client) query(params *QueryParam) error {
// Map the in-progress responses
inprogress := make(map[string]*ServiceEntry)
// Listen until we reach the timeout
finish := time.After(params.Timeout)
for {
select {
case resp := <-msgCh:
@ -335,7 +341,7 @@ func (c *client) query(params *QueryParam) error {
inp.sent = true
select {
case params.Entries <- inp:
case <-finish:
case <-params.Context.Done():
return nil
}
} else {
@ -347,7 +353,7 @@ func (c *client) query(params *QueryParam) error {
log.Printf("[ERR] mdns: Failed to query instance %s: %v", inp.Name, err)
}
}
case <-finish:
case <-params.Context.Done():
return nil
}
}