feat(get): get from quorum #866

xiang90 · Jun 23, 2014

I do not suggest people to use this function unless they know exactly what they want.
This is just for linearizability in real time order. Index is a better indication of the actual order of events.
Nothing to do with etcd's write consensus/consistency model.

bmizerany · Jun 23, 2014

LGTM. It agree it needs a warning in the docs.

yichengq · Jun 23, 2014

lgtm. A smoke test for it would be great.

philips · Jun 23, 2014

We need to add documentation for this and figure out what happens in a mixed version cluster.

xiang90 feat(get): get from quorum 973bde9

philips merged commit 1cffdb3 into master Jul 9, 2014

philips referenced this pull request Jul 9, 2014
Closed
Consistent reads are not consistent #741

yichengq deleted the qread branch Aug 4, 2014

      	vars := mux.Vars(req)
      	key := "/" + vars["key"]
+    +	recursive := (req.FormValue("recursive") == "true")
+    +	sort := (req.FormValue("sorted") == "true")
+    +
+    +	if req.FormValue("quorum") == "true" {
+    +		c := s.Store().CommandFactory().CreateGetCommand(key, recursive, sort)
+    +		return s.Dispatch(c, w, req)
+    +	}
+    +
      	// Help client to redirect the request to the current leader
      	if req.FormValue("consistent") == "true" && s.State() != raft.Leader {
      		leader := s.Leader()
      		return nil
      	}
-    -	recursive := (req.FormValue("recursive") == "true")
-    -	sort := (req.FormValue("sorted") == "true")
      	waitIndex := req.FormValue("waitIndex")
      	stream := (req.FormValue("stream") == "true")

@@ @@ -24,6 +24,7 @@ type CommandFactory interface { @@
      		prevIndex uint64, expireTime time.Time) raft.Command
      	CreateCompareAndDeleteCommand(key string, prevValue string, prevIndex uint64) raft.Command
      	CreateSyncCommand(now time.Time) raft.Command
+    +	CreateGetCommand(key string, recursive, sorted bool) raft.Command
      }
      // RegisterCommandFactory adds a command factory to the global registry.

      		Time: time.Now(),
      	}
      }
+    +
+    +func (f *CommandFactory) CreateGetCommand(key string, recursive, sorted bool) raft.Command {
+    +	return &GetCommand{
+    +		Key:       key,
+    +		Recursive: recursive,
+    +		Sorted:    sorted,
+    +	}
+    +}

@@ -0,0 +1,35 @@
+    +package v2
+    +
+    +import (
+    +	"github.com/coreos/etcd/log"
+    +	"github.com/coreos/etcd/store"
+    +	"github.com/coreos/etcd/third_party/github.com/goraft/raft"
+    +)
+    +
+    +func init() {
+    +	raft.RegisterCommand(&GetCommand{})
+    +}
+    +
+    +// The GetCommand gets a key from the Store.
+    +type GetCommand struct {
+    +	Key       string `json:"key"`
+    +	Recursive bool   `json:"recursive"`
+    +	Sorted    bool   `json:sorted`
+    +}
+    +
+    +// The name of the get command in the log
+    +func (c *GetCommand) CommandName() string {
+    +	return "etcd:get"
+    +}
+    +
+    +// Get the key
+    +func (c *GetCommand) Apply(context raft.Context) (interface{}, error) {
+    +	s, _ := context.Server().StateMachine().(store.Store)
+    +	e, err := s.Get(c.Key, c.Recursive, c.Sorted)
+    +
+    +	if err != nil {
+    +		log.Debug(err)
+    +		return nil, err
+    +	}
+    +	return e, nil
+    +}

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feat(get): get from quorum #866

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Consistent reads are not consistent #741