Vladimir Domnich
b1ec6d562c
At the moment we don't need logic that swings back to beginning of registry when all objects have been processed. So, for now we can stop iterating and return an error when selector reaches the end of registry. Signed-off-by: Vladimir Domnich <v.domnich@yadro.com>
69 lines
1.6 KiB
Go
69 lines
1.6 KiB
Go
package registry
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import (
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"encoding/json"
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"errors"
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"sync"
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"go.etcd.io/bbolt"
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)
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type ObjSelector struct {
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boltDB *bbolt.DB
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mu sync.Mutex
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lastId uint64
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objStatus string
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}
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func (o *ObjSelector) NextObject() (*ObjectInfo, error) {
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var foundObj *ObjectInfo
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err := o.boltDB.View(func(tx *bbolt.Tx) error {
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b := tx.Bucket([]byte(bucketName))
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if b == nil {
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return nil
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}
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c := b.Cursor()
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// We use mutex so that multiple VUs won't attempt to modify lastId simultaneously
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// TODO: consider singleton channel that will produce those ids on demand
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o.mu.Lock()
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defer o.mu.Unlock()
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// Establish the start position for searching the next object:
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// If we should go from the beginning (lastId=0), then we start from the first element
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// Otherwise we start from the key right after the lastId
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var keyBytes, objBytes []byte
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if o.lastId == 0 {
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keyBytes, objBytes = c.First()
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} else {
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c.Seek(encodeId(o.lastId))
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keyBytes, objBytes = c.Next()
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}
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// Iterate over objects to find the next object in the target status
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var obj ObjectInfo
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for ; keyBytes != nil; keyBytes, objBytes = c.Next() {
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if objBytes != nil {
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if err := json.Unmarshal(objBytes, &obj); err != nil {
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// Ignore malformed objects for now. Maybe it should be panic?
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continue
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}
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// If we reached an object in the target status, stop iterating
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if obj.Status == o.objStatus {
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foundObj = &obj
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break
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}
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}
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}
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// Update the last key
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if keyBytes != nil {
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o.lastId = decodeId(keyBytes)
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return nil
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}
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return errors.New("no objects are available")
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})
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return foundObj, err
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}
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