Don't rely on lucky timings when sending messages from the provider.

lib/db/api.js

@@ -84,6 +84,12 @@ dbapi.setDeviceAbsent = function(serial) {
   }))
 }
 
+dbapi.setDeviceChannel = function(serial, channel) {
+  return db.run(r.table('devices').get(serial).update({
+    channel: channel
+  }))
+}
+
 dbapi.saveDeviceIdentity = function(serial, identity) {
   return db.run(r.table('devices').get(serial).update({
     platform: identity.platform
@@ -105,16 +111,4 @@ dbapi.loadDevice = function(serial) {
   return db.run(r.table('devices').get(serial))
 }
 
-dbapi.ensureDeviceSaved = function(serial) {
-  return dbapi.loadDevice(serial)
-    .then(function(device) {
-      if (!device) {
-        return Promise.delay(100).then(function() {
-          return dbapi.loadDevice(serial)
-        })
-      }
-      return device
-    })
-}
-
 module.exports = dbapi

lib/roles/device.js

@@ -431,8 +431,13 @@ module.exports = function(options) {
     .handler())
 
   function poke() {
-    push.send([wireutil.global,
-      wireutil.makeDevicePokeMessage(options.serial, solo)])
+    push.send([
+      wireutil.global
+    , wireutil.envelope(new wire.DevicePokeMessage(
+        options.serial
+      , solo
+      ))
+    ])
   }
 
   function isGrouped() {

lib/roles/processor.js

@@ -32,10 +32,20 @@ module.exports = function(options) {
   })
 
   devDealer.on('message', wirerouter()
+    // Initial device message
     .on(wire.DevicePresentMessage, function(channel, message, data) {
       dbapi.saveDevice(message.serial, message)
+        .then(function() {
+          devDealer.send([
+            message.provider.channel
+          , wireutil.envelope(new wire.DeviceRegisteredMessage(
+              message.serial
+            ))
+          ])
           appDealer.send([channel, data])
         })
+    })
+    // Workerless messages
     .on(wire.DeviceAbsentMessage, function(channel, message, data) {
       dbapi.setDeviceAbsent(message.serial)
       appDealer.send([channel, data])
@@ -44,6 +54,17 @@ module.exports = function(options) {
       dbapi.saveDeviceStatus(message.serial, message.status)
       appDealer.send([channel, data])
     })
+    // Worker initialized
+    .on(wire.DevicePokeMessage, function(channel, message) {
+      dbapi.setDeviceChannel(message.serial, message.channel)
+        .then(function() {
+          devDealer.send([
+            message.channel
+          , wireutil.envelope(new wire.ProbeMessage())
+          ])
+        })
+    })
+    // Worker messages
     .on(wire.JoinGroupMessage, function(channel, message, data) {
       dbapi.setDeviceOwner(message.serial, message.owner)
       appDealer.send([channel, data])
@@ -56,12 +77,6 @@ module.exports = function(options) {
       dbapi.saveDeviceLog(message.serial, message)
       appDealer.send([channel, data])
     })
-    .on(wire.DevicePokeMessage, function(channel, message) {
-      dbapi.ensureDeviceSaved(message.serial)
-        .then(function() {
-          devDealer.send([message.channel, wireutil.makeProbeMessage()])
-        })
-    })
     .on(wire.DeviceIdentityMessage, function(channel, message, data) {
       dbapi.saveDeviceIdentity(message.serial, message)
       appDealer.send([channel, data])

lib/roles/provider.js

@@ -9,12 +9,14 @@ var _ = require('lodash')
 var logger = require('../util/logger')
 var wire = require('../wire')
 var wireutil = require('../wire/util')
+var wirerouter = require('../wire/router')
 var procutil = require('../util/procutil')
 
 module.exports = function(options) {
   var log = logger.createLogger('provider')
   var client = Promise.promisifyAll(adb.createClient())
   var workers = {}
+  var solo = wireutil.makePrivateChannel()
   var lists = {
     all: []
   , ready: []
@@ -58,6 +60,19 @@ module.exports = function(options) {
     push.connect(endpoint)
   })
 
+  // Input
+  var sub = zmq.socket('sub')
+  options.endpoints.sub.forEach(function(endpoint) {
+    log.info('Receiving input from %s', endpoint)
+    sub.connect(endpoint)
+  })
+
+  // Establish always-on channels
+  ;[solo].forEach(function(channel) {
+    log.info('Subscribing to permanent channel "%s"', channel)
+    sub.subscribe(channel)
+  })
+
   // Track and manage devices
   client.trackDevicesAsync().then(function(tracker) {
     log.info('Tracking devices')
@@ -82,34 +97,53 @@ module.exports = function(options) {
     tracker.on('add', filterDevice(function(device) {
       log.info('Found device "%s" (%s)', device.id, device.type)
 
+      var privateTracker = new events.EventEmitter()
+        , timer
+        , worker
+
+      // Wait for others to acknowledge the device
+      var register = new Promise(function(resolve, reject) {
         // Tell others we found a device
         push.send([
           wireutil.global
         , wireutil.envelope(new wire.DevicePresentMessage(
             device.id
-        , options.name
           , wireutil.toDeviceStatus(device.type)
+          , new wire.ProviderMessage(
+              solo
+            , options.name
+            )
           ))
         ])
 
+        privateTracker.once('register', resolve)
+      })
+
+      register.then(function() {
+        log.info('Registered device "%s"', device.id)
+        check()
+      })
+
       // Statistics
       lists.all.push(device.id)
       delayedTotals()
 
-      var privateTracker = new events.EventEmitter()
-        , resolver = Promise.defer()
-        , timer
-        , worker
+      // The device object will be kept up to date by the tracker, except
+      // our custom "present" property
+      _.assign(device, {
+        present: true
+      })
 
       // When any event occurs on the added device
-      function deviceListener(type, device) {
+      function deviceListener(type) {
         // Okay, this is a bit unnecessary but it allows us to get rid of an
         // ugly switch statement and return to the original style.
-        privateTracker.emit(type, device)
+        privateTracker.emit(type)
       }
 
       // When the added device changes
-      function changeListener(device) {
+      function changeListener() {
+        register.then(function() {
           log.info('Device "%s" is now "%s"', device.id, device.type)
 
           // Tell others the device changed
@@ -121,11 +155,13 @@ module.exports = function(options) {
             ))
           ])
 
-        check(device)
+          check()
+        })
       }
 
       // When the added device gets removed
-      function removeListener(device) {
+      function removeListener() {
+        register.then(function() {
           log.info('Lost device "%s" (%s)', device.id, device.type)
 
           clearTimeout(timer)
@@ -141,26 +177,39 @@ module.exports = function(options) {
             ))
           ])
 
-        stop()
+          _.assign(device, {
+            present: false
+          })
+
+          check()
+        })
       }
 
       // Check if we can do anything with the device
-      function check(device) {
+      function check() {
         clearTimeout(timer)
+
+        if (device.present) {
+          // We might get multiple status updates in rapid succession,
+          // so let's wait for a while
           switch (device.type) {
             case 'device':
             case 'emulator':
               timer = setTimeout(work, 100)
               break
             default:
-            stop()
+              timer = setTimeout(stop, 100)
               break
           }
         }
+        else {
+          stop()
+        }
+      }
 
       // Starts a device worker and keeps it alive
       function work() {
-        return worker = workers[device.id] = spawn(device)
+        return worker = workers[device.id] = spawn()
           .then(function() {
             log.info('Device worker "%s" has retired', device.id)
             worker = workers[device.id] = null
@@ -188,7 +237,7 @@ module.exports = function(options) {
       }
 
       // Spawn a device worker
-      function spawn(device) {
+      function spawn() {
         var ports = options.ports.splice(0, 2)
           , proc = options.fork(device, ports)
           , resolver = Promise.defer()
@@ -272,7 +321,6 @@ module.exports = function(options) {
       flippedTracker.on(device.id, deviceListener)
       privateTracker.on('change', changeListener)
       privateTracker.on('remove', removeListener)
-      check(device)
     }))
 
     tracker.on('change', filterDevice(function(device) {
@@ -282,6 +330,12 @@ module.exports = function(options) {
     tracker.on('remove', filterDevice(function(device) {
       flippedTracker.emit(device.id, 'remove', device)
     }))
+
+    sub.on('message', wirerouter()
+      .on(wire.DeviceRegisteredMessage, function(channel, message) {
+        flippedTracker.emit(message.serial, 'register')
+      })
+      .handler())
   })
 
   function gracefullyExit() {

lib/wire/util.js

@@ -40,12 +40,6 @@ var wireutil = {
     , entry.identifier
     ))
   }
-, makeDevicePokeMessage: function(serial, channel) {
-    return wireutil.envelope(new wire.DevicePokeMessage(
-      serial
-    , channel
-    ))
-  }
 , makeDeviceIdentityMessage: function(serial, identity) {
     return wireutil.envelope(new wire.DeviceIdentityMessage(
       serial
@@ -78,9 +72,6 @@ var wireutil = {
       })
     ))
   }
-, makeProbeMessage: function() {
-    return wireutil.envelope(new wire.ProbeMessage())
-  }
 , makeShellCommandMessage: function(channel, command) {
     return wireutil.envelope(new wire.ShellCommandMessage(
       channel

lib/wire/wire.proto

@@ -25,6 +25,7 @@ enum MessageType {
   KeyDownMessage          = 23;
   KeyUpMessage            = 24;
   KeyPressMessage         = 25;
+  DeviceRegisteredMessage = 26;
 }
 
 message Envelope {
@@ -46,10 +47,19 @@ message DeviceLogMessage {
 
 // Introductions
 
+message ProviderMessage {
+  required string channel = 1;
+  required string name = 2;
+}
+
 message DevicePresentMessage {
   required string serial = 1;
-  required string provider = 2;
-  required DeviceStatus status = 4;
+  required DeviceStatus status = 2;
+  required ProviderMessage provider = 3;
+}
+
+message DeviceRegisteredMessage {
+  required string serial = 1;
 }
 
 message DeviceAbsentMessage {