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availability.go
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availability.go
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package api
import (
"context"
"encoding/json"
"net/http"
"sync"
"time"
"github.com/insolar/assured-ledger/ledger-core/configuration"
"github.com/insolar/assured-ledger/ledger-core/instrumentation/inslogger"
)
//go:generate minimock -i github.com/insolar/assured-ledger/ledger-core/application/api.AvailabilityChecker -s _mock.go -g
// AvailabilityChecker component checks if insolar network can't process any new requests
type AvailabilityChecker interface {
IsAvailable(context.Context) bool
}
type keeperResponse struct {
Available bool `json:"available"`
}
// NetworkChecker is AvailabilityChecker implementation that checks can we process any API requests based on keeper status
type NetworkChecker struct {
client *http.Client
enabled bool
keeperURL string
checkPeriod time.Duration
stopped chan struct{}
lock *sync.RWMutex
isAvailable bool
}
func NewNetworkChecker(cfg configuration.AvailabilityChecker) *NetworkChecker {
return &NetworkChecker{
client: &http.Client{
Transport: &http.Transport{},
Timeout: time.Duration(cfg.RequestTimeout) * time.Second,
},
enabled: cfg.Enabled,
keeperURL: cfg.KeeperURL,
checkPeriod: time.Duration(cfg.CheckPeriod) * time.Second,
stopped: make(chan struct{}),
lock: &sync.RWMutex{},
isAvailable: false,
}
}
func (nc *NetworkChecker) Start(ctx context.Context) error {
if !nc.enabled {
nc.lock.Lock()
defer nc.lock.Unlock()
nc.isAvailable = true
return nil
}
go func(ctx context.Context) {
ticker := time.NewTicker(nc.checkPeriod)
defer ticker.Stop()
stop := false
for !stop {
select {
case <-ticker.C:
nc.UpdateAvailability(ctx)
case <-nc.stopped:
stop = true
}
}
nc.stopped <- struct{}{}
}(ctx)
return nil
}
func (nc *NetworkChecker) Stop() {
nc.stopped <- struct{}{}
<-nc.stopped
}
func (nc *NetworkChecker) UpdateAvailability(ctx context.Context) {
logger := inslogger.FromContext(ctx)
logger.Debug("[ NetworkChecker ] update availability started")
resp, err := nc.client.Get(nc.keeperURL)
defer func() {
if resp != nil && resp.Body != nil {
err := resp.Body.Close()
if err != nil {
logger.Error("[ NetworkChecker ] Can't close body: ", err)
}
}
}()
nc.lock.Lock()
defer nc.lock.Unlock()
if err != nil {
nc.isAvailable = false
logger.Error("[ NetworkChecker ] Can't get keeper status: ", err)
return
}
if resp == nil || resp.StatusCode != http.StatusOK {
nc.isAvailable = false
logger.Error("[ NetworkChecker ] Can't get keeper status: no response or bad StatusCode: ", resp.StatusCode)
return
}
respObj := &keeperResponse{}
err = json.NewDecoder(resp.Body).Decode(respObj)
if err != nil {
nc.isAvailable = false
logger.Error("[ NetworkChecker ] Can't get keeper status: Can't decode body: ", err)
return
}
if !respObj.Available {
logger.Warn("[ NetworkChecker ] Network is not available for request processing")
}
nc.isAvailable = respObj.Available
}
func (nc *NetworkChecker) IsAvailable(ctx context.Context) bool {
nc.lock.RLock()
defer nc.lock.RUnlock()
return nc.isAvailable
}
type DummyNetworkChecker struct{}
func NewDummyNetworkChecker(_ configuration.AvailabilityChecker) *DummyNetworkChecker {
return &DummyNetworkChecker{}
}
func (d DummyNetworkChecker) IsAvailable(ctx context.Context) bool { return true }