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
}
+//Database struct is a holder for the internal database instance. Applications
+//can use this exported data type to locally store a reference to database
+//instance returned from NewDabase() function.
+type Database struct {
+ instance iDatabase
+}
+
//NewDatabase creates a connection to database that will be used
-//as a backend for the key-value storage. The returned value shall
-//be given as a parameter when calling NewKeyValStorage
-func NewDatabase() *sdlgoredis.DB {
- return sdlgoredis.Create()
+//as a backend for the key-value storage. The returned value
+//can be reused between multiple SDL instances in which case each instance
+//is using the same connection.
+func NewDatabase() *Database {
+ return &Database{
+ instance: sdlgoredis.Create(),
+ }
}
//NewSdlInstance creates a new sdl instance using the given namespace.
//The database used as a backend is given as a parameter
-func NewSdlInstance(NameSpace string, db iDatabase) *SdlInstance {
+func NewSdlInstance(NameSpace string, db *Database) *SdlInstance {
return &SdlInstance{
nameSpace: NameSpace,
nsPrefix: "{" + NameSpace + "},",
eventSeparator: "___",
- iDatabase: db,
+ iDatabase: db.instance,
}
}
//callback as quickly as possible. E.g. reading in callback context should be avoided
//and using of Go signals is recommended. Also it should be noted that in case of several
//events received from different channels, callbacks are called in series one by one.
+//
+//This function is NOT SAFE FOR CONCURRENT USE by multiple goroutines.
func (s *SdlInstance) SubscribeChannel(cb func(string, ...string), channels ...string) error {
s.SubscribeChannelDB(cb, s.nsPrefix, s.eventSeparator, s.setNamespaceToChannels(channels...)...)
return nil
//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.
if len(channelsAndEvents) == 0 {
return s.Del(keys)
}
- if err := s.checkChannelsAndEvents("RemoveIfAndPublish", channelsAndEvents); err != nil {
+ if err := s.checkChannelsAndEvents("RemoveAllAndPublish", channelsAndEvents); err != nil {
return err
}
channelsAndEventsPrepared := s.prepareChannelsAndEvents(channelsAndEvents)
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)
+ SubscribeChannelDB(cb func(string, ...string), channelPrefix, eventSeparator string, channels ...string)
UnsubscribeChannelDB(channels ...string)
MSet(pairs ...interface{}) error
MSetMPub(channelsAndEvents []string, pairs ...interface{}) error
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