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

     1  package v2
     2  
     3  import (
     4  	"encoding/json"
     5  	"fmt"
     6  	"net/http"
     7  	"net/url"
     8  	"strconv"
     9  
    10  	etcdErr "github.com/coreos/etcd/error"
    11  	"github.com/coreos/etcd/log"
    12  	"github.com/coreos/etcd/third_party/github.com/coreos/raft"
    13  	"github.com/coreos/etcd/third_party/github.com/gorilla/mux"
    14  )
    15  
    16  func GetHandler(w http.ResponseWriter, req *http.Request, s Server) error {
    17  	vars := mux.Vars(req)
    18  	key := "/" + vars["key"]
    19  
    20  	// Help client to redirect the request to the current leader
    21  	if req.FormValue("consistent") == "true" && s.State() != raft.Leader {
    22  		leader := s.Leader()
    23  		hostname, _ := s.ClientURL(leader)
    24  
    25  		url, err := url.Parse(hostname)
    26  		if err != nil {
    27  			log.Warn("Redirect cannot parse hostName ", hostname)
    28  			return err
    29  		}
    30  		url.RawQuery = req.URL.RawQuery
    31  		url.Path = req.URL.Path
    32  
    33  		log.Debugf("Redirect consistent get to %s", url.String())
    34  		http.Redirect(w, req, url.String(), http.StatusTemporaryRedirect)
    35  		return nil
    36  	}
    37  
    38  	recursive := (req.FormValue("recursive") == "true")
    39  	sort := (req.FormValue("sorted") == "true")
    40  	waitIndex := req.FormValue("waitIndex")
    41  	stream := (req.FormValue("stream") == "true")
    42  
    43  	if req.FormValue("wait") == "true" {
    44  		return handleWatch(key, recursive, stream, waitIndex, w, s)
    45  	}
    46  
    47  	return handleGet(key, recursive, sort, w, s)
    48  }
    49  
    50  func handleWatch(key string, recursive, stream bool, waitIndex string, w http.ResponseWriter, s Server) error {
    51  	// Create a command to watch from a given index (default 0).
    52  	var sinceIndex uint64 = 0
    53  	var err error
    54  
    55  	if waitIndex != "" {
    56  		sinceIndex, err = strconv.ParseUint(waitIndex, 10, 64)
    57  		if err != nil {
    58  			return etcdErr.NewError(etcdErr.EcodeIndexNaN, "Watch From Index", s.Store().Index())
    59  		}
    60  	}
    61  
    62  	watcher, err := s.Store().Watch(key, recursive, stream, sinceIndex)
    63  	if err != nil {
    64  		return err
    65  	}
    66  
    67  	cn, _ := w.(http.CloseNotifier)
    68  	closeChan := cn.CloseNotify()
    69  
    70  	writeHeaders(w, s)
    71  
    72  	if stream {
    73  		// watcher hub will not help to remove stream watcher
    74  		// so we need to remove here
    75  		defer watcher.Remove()
    76  		for {
    77  			select {
    78  			case <-closeChan:
    79  				return nil
    80  			case event, ok := <-watcher.EventChan:
    81  				if !ok {
    82  					// If the channel is closed this may be an indication of
    83  					// that notifications are much more than we are able to
    84  					// send to the client in time. Then we simply end streaming.
    85  					return nil
    86  				}
    87  
    88  				b, _ := json.Marshal(event)
    89  				_, err := w.Write(b)
    90  				if err != nil {
    91  					return nil
    92  				}
    93  				w.(http.Flusher).Flush()
    94  			}
    95  		}
    96  	}
    97  
    98  	select {
    99  	case <-closeChan:
   100  		watcher.Remove()
   101  	case event := <-watcher.EventChan:
   102  		b, _ := json.Marshal(event)
   103  		w.Write(b)
   104  	}
   105  	return nil
   106  }
   107  
   108  func handleGet(key string, recursive, sort bool, w http.ResponseWriter, s Server) error {
   109  	event, err := s.Store().Get(key, recursive, sort)
   110  	if err != nil {
   111  		return err
   112  	}
   113  
   114  	writeHeaders(w, s)
   115  	b, _ := json.Marshal(event)
   116  	w.Write(b)
   117  	return nil
   118  }
   119  
   120  func writeHeaders(w http.ResponseWriter, s Server) {
   121  	w.Header().Set("Content-Type", "application/json")
   122  	w.Header().Add("X-Etcd-Index", fmt.Sprint(s.Store().Index()))
   123  	w.Header().Add("X-Raft-Index", fmt.Sprint(s.CommitIndex()))
   124  	w.Header().Add("X-Raft-Term", fmt.Sprint(s.Term()))
   125  	w.WriteHeader(http.StatusOK)
   126  }