Reduce risk of file-system corruption / inconsistencies

The migration nonce is now stored in `app.json` file instead of
separate `migration.json`. It will ensure consistency between nonce
and app data, because the file is written in atomic way.

Migration handle legacy migration file and remove it properly.

src/migrations/index.js

@@ -8,14 +8,16 @@ import migrations from './migrations'
 
 // Logic to run all the migrations based on what was not yet run:
 export const runMigrations = async (): Promise<void> => {
-  const current = await db.getNamespace('migrations')
+  // Legacy: the migration nonce was previously stored in separate file
+  // it can happen, so we have to check it from here also.
+  const current = (await db.getKey('app', 'migrations')) || (await db.getNamespace('migrations'))
 
   let { nonce } = current || { nonce: migrations.length }
   const outdated = migrations.length - nonce
 
   if (!outdated) {
     if (!current) {
-      await db.setNamespace('migrations', { nonce })
+      await db.setKey('app', 'migrations.nonce', nonce)
     }
     return
   }
@@ -31,6 +33,6 @@ export const runMigrations = async (): Promise<void> => {
     }
     logger.log(`${outdated} migration(s) performed.`)
   } finally {
-    await db.setNamespace('migrations', { nonce })
+    await db.setKey('app', 'migrations.nonce', nonce)
   }
 }

src/migrations/migrations.js

@@ -37,6 +37,17 @@ const migrations: Migration[] = [
       )
     },
   },
+  {
+    doc: 'merging migrations into app.json',
+    run: async () => {
+      const migrations = await db.getNamespace('migrations')
+      await db.setKey('app', 'migrations', migrations)
+      const dbPath = db.getDBPath()
+      try {
+        await fsUnlink(path.resolve(dbPath, 'migrations.json'))
+      } catch (err) {} // eslint-disable-line
+    },
+  },
 ]
 
 async function getFileData(dbPath, fileName) {

src/migrations/migrations.spec.js

@@ -12,6 +12,7 @@ import db from 'helpers/db'
 
 const rimraf = promisify(rimrafModule)
 const fsReaddir = promisify(fs.readdir)
+const fsReadFile = promisify(fs.readFile)
 
 const tmpDir = os.tmpdir()
 
@@ -20,14 +21,12 @@ const accountsTransform = {
   set: encodeAccountsModel,
 }
 
-describe('migration 1', () => {
+describe('from nonce 0', () => {
   describe('without encryption', () => {
     test('merging db files', async () => {
       const dir = await extractMock('userdata_v1.0.5_mock-01')
-      let files
       db.init(dir)
-      files = await fsReaddir(dir)
-      expect(files).toEqual([
+      await expectFiles(dir, [
         'accounts.json',
         'countervalues.json',
         'migrations.json',
@@ -35,8 +34,7 @@ describe('migration 1', () => {
         'user.json',
       ])
       await runMigrations()
-      files = await fsReaddir(dir)
-      expect(files).toEqual(['app.json', 'migrations.json', 'windowParams.json'])
+      await expectFiles(dir, ['app.json', 'windowParams.json'])
       db.init(dir)
       db.registerTransform('app', 'accounts', accountsTransform)
       const accounts = await db.getKey('app', 'accounts')
@@ -53,9 +51,12 @@ describe('migration 1', () => {
 
     test('handle missing file without crash', async () => {
       const dir = await extractMock('userdata_v1.0.5_mock-03-missing-file')
-      let files
-      files = await fsReaddir(dir)
-      expect(files).toEqual(['countervalues.json', 'migrations.json', 'settings.json', 'user.json'])
+      await expectFiles(dir, [
+        'countervalues.json',
+        'migrations.json',
+        'settings.json',
+        'user.json',
+      ])
       db.init(dir)
       let err
       try {
@@ -64,15 +65,12 @@ describe('migration 1', () => {
         err = e
       }
       expect(err).toBeUndefined()
-      files = await fsReaddir(dir)
-      expect(files).toEqual(['app.json', 'migrations.json', 'windowParams.json'])
+      await expectFiles(dir, ['app.json', 'windowParams.json'])
     })
 
     test('handle where app.json is already present', async () => {
       const dir = await extractMock('userdata_v1.0.5_mock-04-app-json-present')
-      let files
-      files = await fsReaddir(dir)
-      expect(files).toEqual([
+      await expectFiles(dir, [
         'accounts.json',
         'app.json',
         'countervalues.json',
@@ -82,8 +80,7 @@ describe('migration 1', () => {
       ])
       db.init(dir)
       await runMigrations()
-      files = await fsReaddir(dir)
-      expect(files).toEqual(['app.json', 'migrations.json', 'windowParams.json'])
+      await expectFiles(dir, ['app.json', 'windowParams.json'])
     })
   })
 
@@ -94,8 +91,7 @@ describe('migration 1', () => {
       db.registerTransform('app', 'accounts', accountsTransform)
       await runMigrations()
       await db.setEncryptionKey('app', 'accounts', 'passw0rd')
-      const files = await fsReaddir(dir)
-      expect(files).toEqual(['app.json', 'migrations.json', 'windowParams.json'])
+      await expectFiles(dir, ['app.json', 'windowParams.json'])
       const accounts = await db.getKey('app', 'accounts')
       expect(accounts.length).toBe(6)
       expect(accounts[0].balance).toBeInstanceOf(BigNumber)
@@ -114,6 +110,21 @@ describe('migration 1', () => {
   })
 })
 
+describe('from nonce 1', () => {
+  test('merging migration file into app file', async () => {
+    const dir = await extractMock('userdata_v1.1.1_mock-01')
+    await expectFiles(dir, ['app.json', 'migrations.json', 'windowParams.json'])
+    const migrationsBefore = await fsReadFile(path.resolve(dir, 'migrations.json'), 'utf-8')
+    expect(migrationsBefore).toBe('{"data":{"nonce":1}}')
+    db.init(dir)
+    db.registerTransform('app', 'accounts', accountsTransform)
+    await runMigrations()
+    await expectFiles(dir, ['app.json', 'windowParams.json'])
+    const migrations = await db.getKey('app', 'migrations')
+    expect(migrations).toEqual({ nonce: 2 })
+  })
+})
+
 async function extractMock(mockName) {
   const destDirectory = path.resolve(tmpDir, mockName)
   const zipFilePath = path.resolve(__dirname, 'mocks', `${mockName}.zip`)
@@ -129,3 +140,8 @@ function extractZip(zipFilePath, destDirectory) {
     childProcess.on('error', reject)
   })
 }
+
+async function expectFiles(dir, expectedFiles) {
+  const files = await fsReaddir(dir)
+  expect(files).toEqual(expectedFiles)
+}