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cache.go
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cache.go
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package datastore
import (
"fmt"
"sync"
store "github.com/docker/docker/libnetwork/internal/kvstore"
)
type kvMap map[string]KVObject
type cache struct {
mu sync.Mutex
kmm map[string]kvMap
ds store.Store
}
func newCache(ds store.Store) *cache {
return &cache{kmm: make(map[string]kvMap), ds: ds}
}
func (c *cache) kmap(kvObject KVObject) (kvMap, error) {
var err error
c.mu.Lock()
keyPrefix := Key(kvObject.KeyPrefix()...)
kmap, ok := c.kmm[keyPrefix]
c.mu.Unlock()
if ok {
return kmap, nil
}
kmap = kvMap{}
kvList, err := c.ds.List(keyPrefix)
if err != nil {
if err == store.ErrKeyNotFound {
// If the store doesn't have anything then there is nothing to
// populate in the cache. Just bail out.
goto out
}
return nil, fmt.Errorf("error while populating kmap: %v", err)
}
for _, kvPair := range kvList {
// Ignore empty kvPair values
if len(kvPair.Value) == 0 {
continue
}
dstO := kvObject.New()
err = dstO.SetValue(kvPair.Value)
if err != nil {
return nil, err
}
// Make sure the object has a correct view of the DB index in
// case we need to modify it and update the DB.
dstO.SetIndex(kvPair.LastIndex)
kmap[Key(dstO.Key()...)] = dstO
}
out:
// There may multiple go routines racing to fill the
// cache. The one which places the kmap in c.kmm first
// wins. The others should just use what the first populated.
c.mu.Lock()
kmapNew, ok := c.kmm[keyPrefix]
if ok {
c.mu.Unlock()
return kmapNew, nil
}
c.kmm[keyPrefix] = kmap
c.mu.Unlock()
return kmap, nil
}
func (c *cache) add(kvObject KVObject, atomic bool) error {
kmap, err := c.kmap(kvObject)
if err != nil {
return err
}
c.mu.Lock()
// If atomic is true, cache needs to maintain its own index
// for atomicity and the add needs to be atomic.
if atomic {
if prev, ok := kmap[Key(kvObject.Key()...)]; ok {
if prev.Index() != kvObject.Index() {
c.mu.Unlock()
return ErrKeyModified
}
}
// Increment index
index := kvObject.Index()
index++
kvObject.SetIndex(index)
}
kmap[Key(kvObject.Key()...)] = kvObject
c.mu.Unlock()
return nil
}
func (c *cache) del(kvObject KVObject, atomic bool) error {
kmap, err := c.kmap(kvObject)
if err != nil {
return err
}
c.mu.Lock()
// If atomic is true, cache needs to maintain its own index
// for atomicity and del needs to be atomic.
if atomic {
if prev, ok := kmap[Key(kvObject.Key()...)]; ok {
if prev.Index() != kvObject.Index() {
c.mu.Unlock()
return ErrKeyModified
}
}
}
delete(kmap, Key(kvObject.Key()...))
c.mu.Unlock()
return nil
}
func (c *cache) get(kvObject KVObject) error {
kmap, err := c.kmap(kvObject)
if err != nil {
return err
}
c.mu.Lock()
defer c.mu.Unlock()
o, ok := kmap[Key(kvObject.Key()...)]
if !ok {
return ErrKeyNotFound
}
return o.CopyTo(kvObject)
}
func (c *cache) list(kvObject KVObject) ([]KVObject, error) {
kmap, err := c.kmap(kvObject)
if err != nil {
return nil, err
}
c.mu.Lock()
defer c.mu.Unlock()
var kvol []KVObject
for _, v := range kmap {
kvol = append(kvol, v)
}
return kvol, nil
}