package sdlgo
import (
+ "crypto/rand"
+ "encoding/base64"
"errors"
"fmt"
+ "io"
"reflect"
"strings"
+ "sync"
+ "time"
"gerrit.o-ran-sc.org/r/ric-plt/sdlgo/internal/sdlgoredis"
)
nameSpace string
nsPrefix string
eventSeparator string
+ mutex sync.Mutex
+ tmp []byte
iDatabase
}
//given channel.
func (s *SdlInstance) SetIfNotExistsAndPublish(channelsAndEvents []string, key string, data interface{}) (bool, error) {
if len(channelsAndEvents) == 0 {
- return s.SetNX(s.nsPrefix+key, data)
+ return s.SetNX(s.nsPrefix+key, data, 0)
}
if err := s.checkChannelsAndEvents("SetIfNotExistsAndPublish", channelsAndEvents); err != nil {
return false, err
//then it's value is not changed. Checking the key existence and potential set operation
//is done atomically.
func (s *SdlInstance) SetIfNotExists(key string, data interface{}) (bool, error) {
- return s.SetNX(s.nsPrefix+key, data)
+ return s.SetNX(s.nsPrefix+key, data, 0)
}
//RemoveAndPublish removes data from SDL. Operation is done atomically, i.e. either all succeeds or fails.
return retVal, err
}
+func (s *SdlInstance) randomToken() (string, error) {
+ s.mutex.Lock()
+ defer s.mutex.Unlock()
+
+ if len(s.tmp) == 0 {
+ s.tmp = make([]byte, 16)
+ }
+
+ if _, err := io.ReadFull(rand.Reader, s.tmp); err != nil {
+ return "", err
+ }
+
+ return base64.RawURLEncoding.EncodeToString(s.tmp), nil
+}
+
+//LockResource function is used for locking a resource. The resource lock in
+//practice is a key with random value that is set to expire after a time
+//period. The value written to key is a random value, thus only the instance
+//created a lock, can release it. Resource locks are per namespace.
+func (s *SdlInstance) LockResource(resource string, expiration time.Duration, opt *Options) (*Lock, error) {
+ value, err := s.randomToken()
+ if err != nil {
+ return nil, err
+ }
+
+ var retryTimer *time.Timer
+ for i, attempts := 0, opt.getRetryCount()+1; i < attempts; i++ {
+ ok, err := s.SetNX(s.nsPrefix+resource, value, expiration)
+ if err != nil {
+ return nil, err
+ } else if ok {
+ return &Lock{s: s, key: resource, value: value}, nil
+ }
+ if retryTimer == nil {
+ retryTimer = time.NewTimer(opt.getRetryWait())
+ defer retryTimer.Stop()
+ } else {
+ retryTimer.Reset(opt.getRetryWait())
+ }
+
+ select {
+ case <-retryTimer.C:
+ }
+ }
+ return nil, errors.New("Lock not obtained")
+}
+
+//ReleaseResource removes the lock from a resource. If lock is already
+//expired or some other instance is keeping the lock (lock taken after expiration),
+//an error is returned.
+func (l *Lock) ReleaseResource() error {
+ ok, err := l.s.DelIE(l.s.nsPrefix+l.key, l.value)
+
+ if err != nil {
+ return err
+ }
+ if !ok {
+ return errors.New("Lock not held")
+ }
+ return nil
+}
+
+//RefreshResource function can be used to set a new expiration time for the
+//resource lock (if the lock still exists). The old remaining expiration
+//time is overwritten with the given new expiration time.
+func (l *Lock) RefreshResource(expiration time.Duration) error {
+ err := l.s.PExpireIE(l.s.nsPrefix+l.key, l.value, expiration)
+ return err
+}
+
+//CheckResource returns the expiration time left for a resource.
+//If the resource doesn't exist, -2 is returned.
+func (s *SdlInstance) CheckResource(resource string) (time.Duration, error) {
+ result, err := s.PTTL(s.nsPrefix + resource)
+ if err != nil {
+ return 0, err
+ }
+ if result == time.Duration(-1) {
+ return 0, errors.New("invalid resource given, no expiration time attached")
+ }
+ return result, nil
+}
+
+//Options struct defines the behaviour for getting the resource lock.
+type Options struct {
+ //The number of time the lock will be tried.
+ //Default: 0 = no retry
+ RetryCount int
+
+ //Wait between the retries.
+ //Default: 100ms
+ RetryWait time.Duration
+}
+
+func (o *Options) getRetryCount() int {
+ if o != nil && o.RetryCount > 0 {
+ return o.RetryCount
+ }
+ return 0
+}
+
+func (o *Options) getRetryWait() time.Duration {
+ if o != nil && o.RetryWait > 0 {
+ return o.RetryWait
+ }
+ return 100 * time.Millisecond
+}
+
+//Lock struct identifies the resource lock instance. Releasing and adjusting the
+//expirations are done using the methods defined for this struct.
+type Lock struct {
+ s *SdlInstance
+ key string
+ value string
+}
+
type iDatabase interface {
SubscribeChannelDB(cb sdlgoredis.ChannelNotificationCb, channelPrefix, eventSeparator string, channels ...string)
UnsubscribeChannelDB(channels ...string)
Keys(key string) ([]string, error)
SetIE(key string, oldData, newData interface{}) (bool, error)
SetIEPub(channel, message, key string, oldData, newData interface{}) (bool, error)
- SetNX(key string, data interface{}) (bool, error)
+ SetNX(key string, data interface{}, expiration time.Duration) (bool, error)
SetNXPub(channel, message, key string, data interface{}) (bool, error)
DelIE(key string, data interface{}) (bool, error)
DelIEPub(channel, message, key string, data interface{}) (bool, error)
SMembers(key string) ([]string, error)
SIsMember(key string, data interface{}) (bool, error)
SCard(key string) (int64, error)
+ PTTL(key string) (time.Duration, error)
+ PExpireIE(key string, data interface{}, expiration time.Duration) error
}
Code Review / ric-plt / sdlgo.git / blobdiff