background - introduce ObservableStore

7 files changed, 163 insertions, 109 deletions

diff --git a/app/scripts/lib/config-manager.js b/app/scripts/lib/config-manager.js
index 3a1f12ac0..01e6ccc3c 100644
--- a/app/scripts/lib/config-manager.js
+++ b/app/scripts/lib/config-manager.js
@@ -19,6 +19,7 @@ module.exports = ConfigManager
 function ConfigManager (opts) {
   // ConfigManager is observable and will emit updates
   this._subs = []
+  this.store = opts.store
 
   /* The migrator exported on the config-manager
    * has two methods the user should be concerned with:
@@ -36,12 +37,9 @@ function ConfigManager (opts) {
     // config data format, and returns the new one.
     migrations: migrations,
 
-    // How to load initial config.
-    // Includes step on migrating pre-pojo-migrator data.
-    loadData: opts.loadData,
-
-    // How to persist migrated config.
-    setData: opts.setData,
+    // Data persistence methods
+    loadData: () => this.store.get(),
+    setData: (value) => this.store.put(value),
   })
 }
 
diff --git a/app/scripts/lib/inpage-provider.js b/app/scripts/lib/inpage-provider.js
index 11bd5cc3a..64301be78 100644
--- a/app/scripts/lib/inpage-provider.js
+++ b/app/scripts/lib/inpage-provider.js
@@ -1,7 +1,7 @@
 const Streams = require('mississippi')
 const StreamProvider = require('web3-stream-provider')
 const ObjectMultiplex = require('./obj-multiplex')
-const RemoteStore = require('./remote-store.js').RemoteStore
+const RemoteStore = require('./observable/remote')
 const createRandomId = require('./random-id')
 
 module.exports = MetamaskInpageProvider
@@ -72,13 +72,13 @@ MetamaskInpageProvider.prototype.send = function (payload) {
 
     case 'eth_accounts':
       // read from localStorage
-      selectedAccount = self.publicConfigStore.get('selectedAccount')
+      selectedAccount = self.publicConfigStore.get().selectedAccount
       result = selectedAccount ? [selectedAccount] : []
       break
 
     case 'eth_coinbase':
       // read from localStorage
-      selectedAccount = self.publicConfigStore.get('selectedAccount')
+      selectedAccount = self.publicConfigStore.get().selectedAccount
       result = selectedAccount || '0x0000000000000000000000000000000000000000'
       break
 
@@ -117,9 +117,15 @@ MetamaskInpageProvider.prototype.isMetaMask = true
 
 function remoteStoreWithLocalStorageCache (storageKey) {
   // read local cache
-  var initState = JSON.parse(localStorage[storageKey] || '{}')
-  var store = new RemoteStore(initState)
-  // cache the latest state locally
+  let initState
+  try {
+    initState = JSON.parse(localStorage[storageKey] || '{}')
+  } catch (err) {
+    initState = {}
+  }
+  // intialize store
+  const store = new RemoteStore(initState)
+  // write local cache
   store.subscribe(function (state) {
     localStorage[storageKey] = JSON.stringify(state)
   })
diff --git a/app/scripts/lib/observable/host.js b/app/scripts/lib/observable/host.js
new file mode 100644
index 000000000..69f674be8
--- /dev/null
+++ b/app/scripts/lib/observable/host.js
@@ -0,0 +1,50 @@
+const Dnode = require('dnode')
+const ObservableStore = require('./index')
+const endOfStream = require('end-of-stream')
+
+//
+// HostStore
+//
+// plays host to many RemoteStores and sends its state over a stream
+//
+
+class HostStore extends ObservableStore {
+
+  constructor (initState, opts) {
+    super(initState)
+    this.opts = opts || {}
+  }
+
+  createStream () {
+    const self = this
+    // setup remotely exposed api
+    let remoteApi = {}
+    if (!self.opts.readOnly) {
+      remoteApi.put = (newState) => self.put(newState)
+    }
+    // listen for connection to remote
+    const dnode = Dnode(remoteApi)
+    dnode.on('remote', (remote) => {
+      // setup update subscription lifecycle
+      const updateHandler = (state) => remote.put(state)
+      self._onConnect(updateHandler)
+      endOfStream(dnode, () => self._onDisconnect(updateHandler))
+    })
+    return dnode
+  }
+
+  _onConnect (updateHandler) {
+    // subscribe to updates
+    this.subscribe(updateHandler)
+    // send state immediately
+    updateHandler(this.get())
+  }
+
+  _onDisconnect (updateHandler) {
+    // unsubscribe to updates
+    this.unsubscribe(updateHandler)
+  }
+
+}
+
+module.exports = HostStore
diff --git a/app/scripts/lib/observable/index.js b/app/scripts/lib/observable/index.js
new file mode 100644
index 000000000..d193e5554
--- /dev/null
+++ b/app/scripts/lib/observable/index.js
@@ -0,0 +1,33 @@
+const EventEmitter = require('events').EventEmitter
+
+class ObservableStore extends EventEmitter {
+
+  constructor (initialState) {
+    super()
+    this._state = initialState
+  }
+
+  get () {
+    return this._state
+  }
+
+  put (newState) {
+    this._put(newState)
+  }
+
+  subscribe (handler) {
+    this.on('update', handler)
+  }
+
+  unsubscribe (handler) {
+    this.removeListener('update', handler)
+  }
+
+  _put (newState) {
+    this._state = newState
+    this.emit('update', newState)
+  }
+
+}
+
+module.exports = ObservableStore
diff --git a/app/scripts/lib/observable/remote.js b/app/scripts/lib/observable/remote.js
new file mode 100644
index 000000000..b5a3254a2
--- /dev/null
+++ b/app/scripts/lib/observable/remote.js
@@ -0,0 +1,51 @@
+const Dnode = require('dnode')
+const ObservableStore = require('./index')
+const endOfStream = require('end-of-stream')
+
+//
+// RemoteStore
+//
+// connects to a HostStore and receives its latest state 
+//
+
+class RemoteStore extends ObservableStore {
+
+  constructor (initState, opts) {
+    super(initState)
+    this.opts = opts || {}
+    this._remote = null
+  }
+
+  put (newState) {
+    if (!this._remote) throw new Error('RemoteStore - "put" called before connection to HostStore')
+    this._put(newState)
+    this._remote.put(newState)
+  }
+
+  createStream () {
+    const self = this
+    const dnode = Dnode({
+      put: (newState) => self._put(newState),
+    })
+    // listen for connection to remote
+    dnode.once('remote', (remote) => {
+      // setup connection lifecycle
+      self._onConnect(remote)
+      endOfStream(dnode, () => self._onDisconnect())
+    })
+    return dnode
+  }
+
+  _onConnect (remote) {
+    this._remote = remote
+    this.emit('connected')
+  }
+
+  _onDisconnect () {
+    this._remote = null
+    this.emit('disconnected')
+  }
+
+}
+
+module.exports = RemoteStore
\ No newline at end of file
diff --git a/app/scripts/lib/observable/util/transform.js b/app/scripts/lib/observable/util/transform.js
new file mode 100644
index 000000000..87946f402
--- /dev/null
+++ b/app/scripts/lib/observable/util/transform.js
@@ -0,0 +1,13 @@
+
+module.exports = transformStore
+
+
+function transformStore(inStore, outStore, stateTransform) {
+  const initState = stateTransform(inStore.get())
+  outStore.put(initState)
+  inStore.subscribe((inState) => {
+    const outState = stateTransform(inState)
+    outStore.put(outState)
+  })
+  return outStore
+}
\ No newline at end of file
diff --git a/app/scripts/lib/remote-store.js b/app/scripts/lib/remote-store.js
deleted file mode 100644
index fbfab7bad..000000000
--- a/app/scripts/lib/remote-store.js
+++ /dev/null
@@ -1,97 +0,0 @@
-const Dnode = require('dnode')
-const inherits = require('util').inherits
-
-module.exports = {
-  HostStore: HostStore,
-  RemoteStore: RemoteStore,
-}
-
-function BaseStore (initState) {
-  this._state = initState || {}
-  this._subs = []
-}
-
-BaseStore.prototype.set = function (key, value) {
-  throw Error('Not implemented.')
-}
-
-BaseStore.prototype.get = function (key) {
-  return this._state[key]
-}
-
-BaseStore.prototype.subscribe = function (fn) {
-  this._subs.push(fn)
-  var unsubscribe = this.unsubscribe.bind(this, fn)
-  return unsubscribe
-}
-
-BaseStore.prototype.unsubscribe = function (fn) {
-  var index = this._subs.indexOf(fn)
-  if (index !== -1) this._subs.splice(index, 1)
-}
-
-BaseStore.prototype._emitUpdates = function (state) {
-  this._subs.forEach(function (handler) {
-    handler(state)
-  })
-}
-
-//
-// host
-//
-
-inherits(HostStore, BaseStore)
-function HostStore (initState, opts) {
-  BaseStore.call(this, initState)
-}
-
-HostStore.prototype.set = function (key, value) {
-  this._state[key] = value
-  process.nextTick(this._emitUpdates.bind(this, this._state))
-}
-
-HostStore.prototype.createStream = function () {
-  var dnode = Dnode({
-    // update: this._didUpdate.bind(this),
-  })
-  dnode.on('remote', this._didConnect.bind(this))
-  return dnode
-}
-
-HostStore.prototype._didConnect = function (remote) {
-  this.subscribe(function (state) {
-    remote.update(state)
-  })
-  remote.update(this._state)
-}
-
-//
-// remote
-//
-
-inherits(RemoteStore, BaseStore)
-function RemoteStore (initState, opts) {
-  BaseStore.call(this, initState)
-  this._remote = null
-}
-
-RemoteStore.prototype.set = function (key, value) {
-  this._remote.set(key, value)
-}
-
-RemoteStore.prototype.createStream = function () {
-  var dnode = Dnode({
-    update: this._didUpdate.bind(this),
-  })
-  dnode.once('remote', this._didConnect.bind(this))
-  return dnode
-}
-
-RemoteStore.prototype._didConnect = function (remote) {
-  this._remote = remote
-}
-
-RemoteStore.prototype._didUpdate = function (state) {
-  this._state = state
-  this._emitUpdates(state)
-}