From 34a1621c0ae9f6fe787bd640b224bc2333d200df Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ga=C3=ABtan=20Renaudeau?= <gaetan.renaudeau@ledger.fr>
Date: Wed, 6 Jun 2018 10:31:18 +0200
Subject: [PATCH] debounce the device add/remove + better logs

---
 src/commands/listenDevices.js | 51 ++++++++++++++++++++++++++++++++++-
 src/helpers/ipc.js            |  9 ++++---
 2 files changed, 55 insertions(+), 5 deletions(-)

diff --git a/src/commands/listenDevices.js b/src/commands/listenDevices.js
index e523750a..529250fb 100644
--- a/src/commands/listenDevices.js
+++ b/src/commands/listenDevices.js
@@ -4,6 +4,55 @@ import { createCommand } from 'helpers/ipc'
 import { Observable } from 'rxjs'
 import CommNodeHid from '@ledgerhq/hw-transport-node-hid'
 
-const cmd = createCommand('listenDevices', () => Observable.create(CommNodeHid.listen))
+const DEBOUNCE_REMOVE_DEVICE_EVENT = 500
+
+const cmd = createCommand('listenDevices', () =>
+  Observable.create(o => {
+    const pendingRemovePerPath = {}
+    const sub = CommNodeHid.listen({
+      next: e => {
+        // debounce the add/remove in case we see quick `remove,add` events on same path.
+        switch (e.type) {
+          case 'add': {
+            const pendingRemove = pendingRemovePerPath[e.descriptor]
+            if (pendingRemove) {
+              console.warn(`Skipping remove/add usb event for ${e.descriptor}`)
+              // there where a recent "remove" event, we don't emit add because we didn't emit "remove" yet.
+              clearTimeout(pendingRemove)
+              delete pendingRemovePerPath[e.descriptor]
+            } else {
+              // if there were no recent "remove", we just emit the "add"
+              o.next(e)
+            }
+            break
+          }
+          case 'remove': {
+            // we we always debounce the "remove" event. emit it a bit later in case a "add" of same descriptor happen soon.
+            if (pendingRemovePerPath[e.descriptor]) {
+              clearTimeout(pendingRemovePerPath[e.descriptor])
+            }
+            pendingRemovePerPath[e.descriptor] = setTimeout(() => {
+              delete pendingRemovePerPath[e.descriptor]
+              o.next(e)
+            }, DEBOUNCE_REMOVE_DEVICE_EVENT)
+            break
+          }
+          default:
+            o.next(e)
+        }
+      },
+      complete: () => {
+        o.complete()
+      },
+      error: err => {
+        o.error(err)
+      },
+    })
+    return () => {
+      Object.keys(pendingRemovePerPath).map(k => clearTimeout(pendingRemovePerPath[k]))
+      sub.unsubscribe()
+    }
+  }),
+)
 
 export default cmd
diff --git a/src/helpers/ipc.js b/src/helpers/ipc.js
index c7fa28f7..25053ef5 100644
--- a/src/helpers/ipc.js
+++ b/src/helpers/ipc.js
@@ -37,6 +37,7 @@ function ipcRendererSendCommand<In, A>(id: string, data: In): Observable<A> {
   const { ipcRenderer } = require('electron')
   return Observable.create(o => {
     const requestId: string = uuidv4()
+    const startTime = Date.now()
 
     const unsubscribe = () => {
       ipcRenderer.send('command-unsubscribe', { requestId })
@@ -47,20 +48,20 @@ function ipcRendererSendCommand<In, A>(id: string, data: In): Observable<A> {
       if (requestId !== msg.requestId) return
       switch (msg.type) {
         case 'NEXT':
-          console.log('<= COMMAND next', msg)
+          console.log(`● CMD ${id}`, msg.data)
           if (msg.data) {
             o.next(msg.data)
           }
           break
 
         case 'COMPLETE':
-          console.log('<= COMMAND complete', msg)
+          console.log(`✔ CMD ${id} finished in ${(Date.now() - startTime).toFixed(0)}ms`)
           o.complete()
           ipcRenderer.removeListener('command-event', handleCommandEvent)
           break
 
         case 'ERROR':
-          console.warn('<= COMMAND error', msg)
+          console.warn(`✖ CMD ${id} error`, msg.data)
           o.error(msg.data)
           ipcRenderer.removeListener('command-event', handleCommandEvent)
           break
@@ -73,7 +74,7 @@ function ipcRendererSendCommand<In, A>(id: string, data: In): Observable<A> {
 
     ipcRenderer.send('command', { id, data, requestId })
 
-    console.log('=> COMMAND', { id, data, requestId })
+    console.log(`CMD ${id}.send(`, data, ')')
 
     return unsubscribe
   })