recv_mds/recv_mds.go

   1 //
   2 // Copyright © 2011-2016 Guy M. Allard
   3 //
   4 // Licensed under the Apache License, Version 2.0 (the "License");
   5 // you may not use this file except in compliance with the License.
   6 // You may obtain a copy of the License at
   7 //
   8 //     http://www.apache.org/licenses/LICENSE-2.0
   9 //
  10 // Unless required by applicable law or agreed to in writing, software
  11 // distributed under the License is distributed on an "AS IS" BASIS,
  12 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13 // See the License for the specific language governing permissions and
  14 // limitations under the License.
  15 //
  16
  17 // Show a number of queue writers and readers operating concurrently.
  18 // Try to be realistic about workloads.
  19 // Receiver checks messages for proper queue and message number.
  20 // All senders and receivers use the same Stomp connection.
  21
  22 /*
  23 Outputs to demonstrate different broker's algorithms for balancing messages across
  24 multiple subscriptions to the same queue.  (One go routine per subscription). In
  25 this example all subscriptions share the same connection/session.  The actual
  26 results can / will likely be slightly surprising.  YMMV.
  27
  28 Prime the queue for this demonstration using publish.go.
  29
  30         Examples:
  31
  32                 # Prime a queue with messages:
  33                 STOMP_PORT=61613 STOMP_NMSGS=10 go run publish.go
  34                 # Review ActiveMQ balancing characteristics.  Note:
  35                 # this will eventually block, and the program will have to be
  36                 # forcibly stopped.
  37                 STOMP_PORT=61613 STOMP_ACKMODE="client-individual" go run recv_mds.go
  38
  39                 # Prime a queue with messages again:
  40                 STOMP_PORT=62613 STOMP_NMSGS=10 go run publish.go
  41                 # Review Apollo balancing characteristics.  Note:
  42                 # this will eventually block, and the program will have to be
  43                 # forcibly stopped.
  44                 STOMP_PORT=62613 STOMP_ACKMODE="client-individual" go run recv_mds.go
  45
  46 */
  47 package main
  48
  49 import (
  50         "log"
  51         "net"
  52         "os"
  53         "runtime"
  54         "time"
  55         //
  56         "github.com/gmallard/stompngo"
  57         // senv methods could be used in general by stompngo clients.
  58
  59         // sngecomm methods are used specifically for these example clients.
  60         "github.com/gmallard/stompngo_examples/sngecomm"
  61 )
  62
  63 var (
  64         exampid = "recv_mds: "
  65         ns      = 4                           // Number of subscriptions
  66         n       net.Conn                      // Network Connection
  67         conn    *stompngo.Connection          // Stomp Connection
  68         ackMode string               = "auto" // ackMode control
  69         port    string
  70         ll      = log.New(os.Stdout, "EMDS ", log.Ldate|log.Lmicroseconds|log.Lshortfile)
  71
  72         tag = "recvmdsmain"
  73 )
  74
  75 func recv(conn *stompngo.Connection, s int) {
  76         ltag := tag + "-recv"
  77
  78         ll.Printf("%stag:%s connsess:%s receiver_starts s:%d\n",
  79                 exampid, ltag, conn.Session(),
  80                 s)
  81
  82         // Setup Headers ...
  83         id := stompngo.Uuid() // Use package convenience function for unique ID
  84         d := sngecomm.Dest()
  85         ackMode = sngecomm.AckMode() // get ack mode
  86
  87         pbc := sngecomm.Pbc() // Print byte count
  88
  89         sc := sngecomm.HandleSubscribe(conn, d, id, ackMode)
  90         // Receive loop.
  91         mc := 0
  92         var md stompngo.MessageData
  93         for {
  94                 select {
  95                 case md = <-sc: // Read a messagedata struct, with a MESSAGE frame
  96                 case md = <-conn.MessageData: // Read a messagedata struct, with a ERROR/RECEIPT frame
  97                         // Frames RECEIPT or ERROR not expected here
  98                         ll.Fatalf("%stag:%s connsess:%s bad_frame md:%v",
  99                                 exampid, ltag, conn.Session(),
 100                                 md) // Handle this ......
 101                 }
 102                 //
 103                 mc++
 104                 if md.Error != nil {
 105                         ll.Fatalf("%stag:%s connsess:%s error_read error:%v",
 106                                 exampid, ltag, conn.Session(),
 107                                 md.Error) // Handle this ......
 108                 }
 109                 ll.Printf("%stag:%s connsess:%s received_message s:%d id:%s mc:%d hdrs:%v\n",
 110                         exampid, ltag, conn.Session(),
 111                         s, id, mc, md.Message.Headers)
 112                 if pbc > 0 {
 113                         maxlen := pbc
 114                         if len(md.Message.Body) < maxlen {
 115                                 maxlen = len(md.Message.Body)
 116                         }
 117                         ss := string(md.Message.Body[0:maxlen])
 118                         ll.Printf("%stag:%s connsess:%s payload body:%s\n",
 119                                 exampid, tag, conn.Session(),
 120                                 ss)
 121                 }
 122
 123                 // time.Sleep(3 * time.Second) // A very arbitrary number
 124                 // time.Sleep(500 * time.Millisecond) // A very arbitrary number
 125                 runtime.Gosched()
 126                 time.Sleep(1500 * time.Millisecond) // A very arbitrary number
 127                 runtime.Gosched()
 128                 if ackMode != "auto" {
 129                         sngecomm.HandleAck(conn, md.Message.Headers, id)
 130                         ll.Printf("%stag:%s connsess:%s ack_complete s:%d id:%s mc:%d\n",
 131                                 exampid, ltag, conn.Session(),
 132                                 s, id, mc)
 133                 }
 134                 runtime.Gosched()
 135         }
 136 }
 137
 138 // Connect to a STOMP broker, receive and ackMode some messages.
 139 // Disconnect never occurs, kill via ^C.
 140 func main() {
 141
 142         // Standard example connect sequence
 143         _, conn, e := sngecomm.CommonConnect(exampid, tag, ll)
 144         if e != nil {
 145                 ll.Fatalf("%stag:%s connsess:%s main_on_connect error:%v",
 146                         exampid, tag, sngecomm.Lcs,
 147                         e.Error()) // Handle this ......
 148         }
 149
 150         for i := 1; i <= ns; i++ {
 151                 go recv(conn, i)
 152         }
 153         ll.Printf("%stag:%s connsess:%s receivers_started\n",
 154                 exampid, tag, conn.Session())
 155
 156         select {} // This will never complete, use ^C to cancel
 157
 158 }