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ping.go
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ping.go
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package forwarder
import (
"context"
"fmt"
"sync"
"time"
"github.com/google/uuid"
"github.com/saiya/mesh_for_home_server/config"
"github.com/saiya/mesh_for_home_server/interfaces"
"github.com/saiya/mesh_for_home_server/logger"
"github.com/saiya/mesh_for_home_server/peering/proto/generated"
)
type pingForwarder struct {
router interfaces.Router
unregisterListen interfaces.RouterUnregister
m sync.Mutex
table map[string]*inFlightPing
}
type inFlightPing struct {
ctx context.Context
ctxCancel context.CancelFunc
sucessCh chan struct{}
}
func NewPingForwarder(router interfaces.Router) interfaces.PingForwarder {
exec := &pingForwarder{
router: router,
table: make(map[string]*inFlightPing),
}
exec.unregisterListen = router.Listen(func(ctx context.Context, from config.NodeID, msg interfaces.Message) error {
pong := msg.GetPong()
if pong != nil {
exec.Pong(ctx, pong)
}
return nil
})
return exec
}
func (exec *pingForwarder) Close(ctx context.Context) error {
exec.m.Lock()
defer exec.m.Unlock()
exec.unregisterListen()
return nil
}
func (exec *pingForwarder) Ping(ctx context.Context, dest config.NodeID, timeout time.Duration) error {
nonce := exec.generateNonce(dest)
logger.GetFrom(ctx).Infow("Executing PING...", "dest", dest, "timeout", timeout, "nonce", nonce)
inflight := &inFlightPing{
sucessCh: make(chan struct{}),
}
inflight.ctx, inflight.ctxCancel = context.WithTimeout(ctx, timeout)
defer inflight.ctxCancel()
func() {
exec.m.Lock()
defer exec.m.Unlock()
exec.table[nonce] = inflight
}()
defer func() {
exec.m.Lock()
defer exec.m.Unlock()
delete(exec.table, nonce)
}()
exec.router.Deliver(ctx, exec.router.NodeID(), dest, &generated.PeerMessage{
Message: &generated.PeerMessage_Ping{
Ping: &generated.Ping{
Payload: nonce,
},
},
})
select {
case <-inflight.sucessCh:
return nil
case <-inflight.ctx.Done():
return inflight.ctx.Err()
}
}
func (exec *pingForwarder) Pong(ctx context.Context, msg *generated.Pong) {
logger.GetFrom(ctx).Infow("PONG received", "nonce", msg.Payload)
var inflight *inFlightPing
func() {
exec.m.Lock()
defer exec.m.Unlock()
inflight = exec.table[msg.Payload]
}()
if inflight == nil {
logger.GetFrom(ctx).Warnw("PONG received but unknown value, skipping...", "nonce", msg.Payload)
}
close(inflight.sucessCh)
}
func (exec *pingForwarder) generateNonce(dest config.NodeID) string {
return fmt.Sprintf("%s$%s$nonce:%s", exec.router.NodeID(), dest, uuid.New().String())
}