github.com/macb/etcd@v0.3.1-0.20140227003422-a60481c6b1a0/store/v2/compare_and_swap_command.go (about)

     1  package v2
     2  
     3  import (
     4  	"time"
     5  
     6  	"github.com/coreos/etcd/log"
     7  	"github.com/coreos/etcd/store"
     8  	"github.com/coreos/etcd/third_party/github.com/coreos/raft"
     9  )
    10  
    11  func init() {
    12  	raft.RegisterCommand(&CompareAndSwapCommand{})
    13  }
    14  
    15  // The CompareAndSwap performs a conditional update on a key in the store.
    16  type CompareAndSwapCommand struct {
    17  	Key		string		`json:"key"`
    18  	Value		string		`json:"value"`
    19  	ExpireTime	time.Time	`json:"expireTime"`
    20  	PrevValue	string		`json:"prevValue"`
    21  	PrevIndex	uint64		`json:"prevIndex"`
    22  }
    23  
    24  // The name of the testAndSet command in the log
    25  func (c *CompareAndSwapCommand) CommandName() string {
    26  	return "etcd:compareAndSwap"
    27  }
    28  
    29  // Set the key-value pair if the current value of the key equals to the given prevValue
    30  func (c *CompareAndSwapCommand) Apply(context raft.Context) (interface{}, error) {
    31  	s, _ := context.Server().StateMachine().(store.Store)
    32  
    33  	e, err := s.CompareAndSwap(c.Key, c.PrevValue, c.PrevIndex, c.Value, c.ExpireTime)
    34  
    35  	if err != nil {
    36  		log.Debug(err)
    37  		return nil, err
    38  	}
    39  
    40  	return e, nil
    41  }