core/local/atom: Migrate Windows updated_at dates

  Stat dates on Windows were previously truncated to the second while
  we now get the milliseconds as well.
  To avoid re-calculating all the local checksums during the initial
  scan because of the date migration, we'll truncate `scan` events
  dates to the second during the first initial scan following the
  publication of v3.28.1 when checking if the checksum of a given file
  can be reused or not.

  When publishing v3.28.2 or greater, we can remove
  `WINDOWS_DATE_MIGRATION_FLAG` and stop truncating dates during the
  initial scan.

  Users who will have skipped the version introducing the flag will
  see all their checksums re-computed.

core/app.js

@@ -13,6 +13,7 @@ const url = require('url')
 const uuid = require('uuid/v4')
 const https = require('https')
 const { createGzip } = require('zlib')
+const semver = require('semver')
 
 require('./globals')
 const pkg = require('../package.json')
@@ -373,6 +374,23 @@ class App {
         )
         wasUpdated = false
       }
+
+      // TODO: remove with flag WINDOWS_DATE_MIGRATION_FLAG
+      try {
+        if (
+          semver.lt(
+            clientInfo.configVersion,
+            config.WINDOWS_DATE_MIGRATION_APP_VERSION
+          )
+        ) {
+          this.config.setFlag(config.WINDOWS_DATE_MIGRATION_FLAG, true)
+        }
+      } catch (err) {
+        log.error(
+          { err, sentry: true },
+          `could not set ${config.WINDOWS_DATE_MIGRATION_FLAG} flag`
+        )
+      }
     }
 
     this.instanciate()

core/config.js

@@ -21,6 +21,22 @@ export type WatcherType = 'atom' | 'chokidar'
 type FileConfig = Object
 */
 
+/* Stat dates on Windows were previously truncated to the second while we now
+ * get the milliseconds as well.
+ * To avoid re-calculating all the local checksums during the initial scan
+ * because of the date migration, we'll truncate `scan` events dates to the
+ * second during the first initial scan following the publication of v3.28.1
+ * when checking if the checksum of a given file can be reused or not.
+ *
+ * When publishing v3.28.2 or greater, we can remove WINDOWS_DATE_MIGRATION_FLAG
+ * and stop truncating dates during the initial scan.
+ *
+ * Users who will have skipped the version introducing the flag will see all
+ * their checksums re-computed.
+ */
+const WINDOWS_DATE_MIGRATION_APP_VERSION = '3.28.1'
+const WINDOWS_DATE_MIGRATION_FLAG = 'roundWindowsDatesToSecondInInitialDiff'
+
 const INVALID_CONFIG_ERROR = 'InvalidConfigError'
 const INVALID_CONFIG_MESSAGE = 'Invalid client configuration'
 class InvalidConfigError extends Error {
@@ -170,6 +186,24 @@ class Config {
     return _.get(this.fileConfig, 'flags', {})
   }
 
+  isFlagActive(flagName /*: string */) /*: boolean */ {
+    return this.flags[flagName] || false
+  }
+
+  setFlag(flag /*: string */, isActive /*: boolean */) {
+    if (
+      typeof flag !== 'string' ||
+      typeof isActive !== 'boolean' ||
+      flag === ''
+    ) {
+      throw new Error(
+        `Invalid flag or value: [String(${flag})] → "${String(isActive)}"`
+      )
+    }
+    _.set(this.fileConfig, `flags.${flag}`, isActive)
+    this.persist()
+  }
+
   get version() /*: ?string */ {
     return _.get(this.fileConfig, 'creds.client.softwareVersion', '')
   }
@@ -288,6 +322,8 @@ function validateWatcherType(watcherType /*: ?string */) /*: ?WatcherType */ {
 
 module.exports = {
   INVALID_CONFIG_ERROR,
+  WINDOWS_DATE_MIGRATION_APP_VERSION,
+  WINDOWS_DATE_MIGRATION_FLAG,
   InvalidConfigError,
   Config,
   environmentWatcherType,

core/local/atom/dispatch.js

@@ -11,6 +11,7 @@ const _ = require('lodash')
 
 const winDetectMove = require('./win_detect_move')
 const { buildDir, buildFile } = require('../../metadata')
+const { WINDOWS_DATE_MIGRATION_FLAG } = require('../../config')
 const logger = require('../../utils/logger')
 
 const STEP_NAME = 'dispatch'
@@ -28,6 +29,7 @@ import type {
 } from './event'
 import type { WinDetectMoveState } from './win_detect_move'
 import type EventEmitter from 'events'
+import type { Config } from '../../config'
 import type Prep from '../../prep'
 import type { Pouch } from '../../pouch'
 import type { Metadata } from '../../metadata'
@@ -41,6 +43,7 @@ type DispatchState = {
 }
 
 type DispatchOptions = {
+  config: Config,
   events: EventEmitter,
   prep: Prep,
   pouch: Pouch,
@@ -133,8 +136,12 @@ async function dispatchEvent(
 }
 
 actions = {
-  initialScanDone: ({ events }) => {
+  initialScanDone: ({ config, events }) => {
     log.info('Initial scan done')
+    // TODO: remove with flag WINDOWS_DATE_MIGRATION_FLAG
+    if (config.isFlagActive(WINDOWS_DATE_MIGRATION_FLAG)) {
+      config.setFlag(WINDOWS_DATE_MIGRATION_FLAG, false)
+    }
     events.emit('initial-scan-done')
   },
 

core/local/atom/initial_diff.js

@@ -12,11 +12,13 @@
 const _ = require('lodash')
 const path = require('path')
 
+const { WINDOWS_DATE_MIGRATION_FLAG } = require('../../config')
 const { kind } = require('../../metadata')
 const logger = require('../../utils/logger')
 const Channel = require('./channel')
 
 /*::
+import type { Config } from '../../config'
 import type { Pouch } from '../../pouch'
 import type { AtomEvent, AtomBatch, EventKind } from './event'
 import type { Metadata } from '../../metadata'
@@ -68,10 +70,10 @@ module.exports = {
 
 function loop(
   channel /*: Channel */,
-  opts /*: { pouch: Pouch, state: InitialDiffState } */
+  opts /*: { config: Config, state: InitialDiffState } */
 ) /*: Channel */ {
   const out = new Channel()
-  initialDiff(channel, out, opts.state).catch(err => {
+  initialDiff(channel, out, opts).catch(err => {
     log.warn({ err })
   })
   return out
@@ -126,7 +128,7 @@ function clearState(state /*: InitialDiffState */) {
 async function initialDiff(
   channel /*: Channel */,
   out /*: Channel */,
-  state /*: InitialDiffState */
+  { config, state } /*: { config: Config, state: InitialDiffState } */
 ) /*: Promise<void> */ {
   // eslint-disable-next-line no-constant-condition
   while (true) {
@@ -140,6 +142,10 @@ async function initialDiff(
         initialScanDone
       }
     } = state
+    // TODO: remove with flag WINDOWS_DATE_MIGRATION_FLAG
+    const truncateWindowsDates = config.isFlagActive(
+      WINDOWS_DATE_MIGRATION_FLAG
+    )
 
     if (initialScanDone) {
       out.push(events)
@@ -189,7 +195,7 @@ async function initialDiff(
               deletedIno: was.local.fileid || was.local.ino
             })
           }
-        } else if (foundUntouchedFile(event, was)) {
+        } else if (foundUntouchedFile(event, was, truncateWindowsDates)) {
           _.set(event, [STEP_NAME, 'md5sumReusedFrom'], was.local.path)
           event.md5sum = was.local.md5sum
         }
@@ -338,8 +344,10 @@ function fixPathsAfterParentMove(renamedEvents, event) {
   }
 }
 
-function contentUpdateTime(event) {
-  return event.stats.mtime.getTime()
+function contentUpdateTime(event, truncateWindowsDates) {
+  return truncateWindowsDates
+    ? event.stats.mtime.getTime() - event.stats.mtime.getMilliseconds()
+    : event.stats.mtime.getTime()
 }
 
 function docUpdateTime(oldLocal) {
@@ -354,12 +362,16 @@ function foundRenamedOrReplacedDoc(event, was) /*: boolean %checks */ {
   return was != null && was.local != null && was.local.path !== event.path
 }
 
-function foundUntouchedFile(event, was) /*: boolean %checks */ {
+function foundUntouchedFile(
+  event,
+  was,
+  truncateWindowsDates
+) /*: boolean %checks */ {
   return (
     event.kind === 'file' &&
     was != null &&
     was.local != null &&
     was.local.md5sum != null &&
-    contentUpdateTime(event) === docUpdateTime(was.local)
+    contentUpdateTime(event, truncateWindowsDates) === docUpdateTime(was.local)
   )
 }

package.json

@@ -118,6 +118,7 @@
     "react-markdown": "^4.3.1",
     "read": "1.0.7",
     "regedit": "^3.0.3",
+    "semver": "^7.3.2",
     "uuid": "^3.3.2",
     "yargs": "^11.0.0"
   },

test/unit/local/atom/dispatch.js

@@ -66,6 +66,7 @@ describe('core/local/atom/dispatch.loop()', function() {
     events = sinon.createStubInstance(SyncState)
     prep = sinon.createStubInstance(Prep)
     stepOptions = {
+      config: this.config,
       events,
       prep,
       pouch: this.pouch,