Monotonic clock

[reliable-chat] / server / server.go

diff --git a/server/server.go b/server/server.go
index c47bfaa2f63849d89376abeac8709d2648d38b83..c3bb59310b8ff28195f299b664cb0bd495c2c03c 100644 (file)
--- a/server/server.go
+++ b/server/server.go
@@ -1,7 +1,25 @@
+/*  reliable-chat - multipath chat
+ *  Copyright (C) 2012  Scott Worley <sworley@chkno.net>
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU Affero General Public License as
+ *  published by the Free Software Foundation, either version 3 of the
+ *  License, or (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU Affero General Public License for more details.
+ *
+ *  You should have received a copy of the GNU Affero General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
 package main
 
 import "container/list"
 import "encoding/json"
+import "expvar"
 import "flag"
 import "log"
 import "net/http"
@@ -9,9 +27,19 @@ import "strconv"
 import "time"
 
 var port = flag.Int("port", 21059, "Port to listen on")
+var localaddress = flag.String("localaddress", "", "Local address to bind to")
+var max_messages = flag.Int("maxmessages", 1000, "Maximum number of messages to retain")
+
+var start_time = expvar.NewInt("start_time")
+var speak_count = expvar.NewInt("speak_count")
+var fetch_count = expvar.NewInt("fetch_count")
+var fetch_wait_count = expvar.NewInt("fetch_wait_count")
+var fetch_wake_count = expvar.NewInt("fetch_wake_count")
+var drop_due_to_limit_count = expvar.NewInt("drop_due_to_limit_count")
 
 type Message struct {
        Time time.Time
+       ID   string
        Text string
 }
 
@@ -25,12 +53,43 @@ type Store struct {
        Get chan *StoreRequest
 }
 
-// TODO: Monotonic clock
+var monotonic_clock chan chan time.Time
+
+const minimum_clock_increment = time.Millisecond
+
+func start_clock() {
+       internal_monotonic_clock := make(chan chan time.Time, 1)
+       go func() {
+               last_time := time.Now()
+       main:
+               for {
+                       select {
+                       case request, ok := <-internal_monotonic_clock:
+                               if !ok {
+                                       break main
+                               }
+                               earliest_acceptable_time := last_time.Add(minimum_clock_increment)
+                               current_time := time.Now()
+                               if current_time.Before(earliest_acceptable_time) {
+                                       current_time = earliest_acceptable_time
+                               }
+                               request <- current_time
+                               last_time = current_time
+                       }
+               }
+       }()
+       monotonic_clock = internal_monotonic_clock
+}
+
+func now() time.Time {
+       c := make(chan time.Time, 0)
+       monotonic_clock <- c
+       return <-c
+}
 
 func manage_store(store Store) {
        messages := list.New()
        message_count := 0
-       max_messages := 1000
        waiting := list.New()
 main:
        for {
@@ -39,23 +98,28 @@ main:
                        if !ok {
                                break main
                        }
-                       messages.PushBack(new_message)
+                       speak_count.Add(1)
                        for waiter := waiting.Front(); waiter != nil; waiter = waiter.Next() {
                                waiter.Value.(*StoreRequest).Messages <- []Message{*new_message}
                                close(waiter.Value.(*StoreRequest).Messages)
+                               fetch_wake_count.Add(1)
                        }
                        waiting.Init()
-                       if message_count < max_messages {
+                       messages.PushBack(new_message)
+                       if message_count < *max_messages {
                                message_count++
                        } else {
                                messages.Remove(messages.Front())
+                               drop_due_to_limit_count.Add(1)
                        }
                case request, ok := <-store.Get:
                        if !ok {
                                break main
                        }
+                       fetch_count.Add(1)
                        if messages.Back() == nil || !request.StartTime.Before(messages.Back().Value.(*Message).Time) {
                                waiting.PushBack(request)
+                               fetch_wait_count.Add(1)
                        } else {
                                start := messages.Back()
                                response_size := 1
@@ -84,6 +148,10 @@ func start_store() Store {
        return store
 }
 
+const robots_txt = `User-agent: *
+Disallow: /
+`
+
 func start_server(store Store) {
        http.HandleFunc("/fetch", func(w http.ResponseWriter, r *http.Request) {
                var since time.Time
@@ -107,17 +175,28 @@ func start_server(store Store) {
                        return
                }
                w.Header().Add("Content-Type", "application/json")
+               w.Header().Add("Access-Control-Allow-Origin", "*")
                w.Write(json_encoded)
        })
 
        http.HandleFunc("/speak", func(w http.ResponseWriter, r *http.Request) {
-               store.Add <- &Message{time.Now(), r.FormValue("text")}
+               store.Add <- &Message{
+                       now(),
+                       r.FormValue("id"),
+                       r.FormValue("text")}
+       })
+
+       http.HandleFunc("/robots.txt", func(w http.ResponseWriter, r *http.Request) {
+               w.Write([]byte(robots_txt))
        })
 
-       log.Fatal(http.ListenAndServe(":" + strconv.Itoa(*port), nil))
+       log.Fatal(http.ListenAndServe(*localaddress+":"+strconv.Itoa(*port), nil))
 }
 
 func main() {
+       flag.Parse()
+       start_clock()
+       start_time.Set(now().UnixNano())
        store := start_store()
        start_server(store)
 }