perf: smaller db close implementation

src/database/Database.js

@@ -7,58 +7,21 @@ import {
   STORE_KEYVALUE
 } from './constants'
 import { uniqEmoji } from './utils/uniqEmoji'
-import { jsonChecksum } from './utils/jsonChecksum'
 import {
   closeDatabase,
   deleteDatabase,
   addOnCloseListener,
-  openDatabase,
-  removeOnCloseListener
+  openDatabase
 } from './databaseLifecycle'
 import {
-  isEmpty, hasData, loadData, getEmojiByGroup,
+  isEmpty, getEmojiByGroup,
   getEmojiBySearchQuery, getEmojiByShortcode, getEmojiByUnicode,
   get, set, getTopFavoriteEmoji, incrementFavoriteEmojiCount
 } from './idbInterface'
 import { log } from '../shared/log'
-import { getETag, getETagAndData } from './utils/ajax'
 import { customEmojiIndex } from './customEmojiIndex'
 import { cleanEmoji } from './utils/cleanEmoji'
-
-async function checkForUpdates (db, dataSource) {
-  // just do a simple HEAD request first to see if the eTags match
-  let emojiBaseData
-  let eTag = await getETag(dataSource)
-  if (!eTag) { // work around lack of ETag/Access-Control-Expose-Headers
-    const eTagAndData = await getETagAndData(dataSource)
-    eTag = eTagAndData[0]
-    emojiBaseData = eTagAndData[1]
-    if (!eTag) {
-      eTag = await jsonChecksum(emojiBaseData)
-    }
-  }
-  if (await hasData(db, dataSource, eTag)) {
-    log('Database already populated')
-  } else {
-    log('Database update available')
-    if (!emojiBaseData) {
-      const eTagAndData = await getETagAndData(dataSource)
-      emojiBaseData = eTagAndData[1]
-    }
-    await loadData(db, emojiBaseData, dataSource, eTag)
-  }
-}
-
-async function loadDataForFirstTime (db, dataSource) {
-  let [eTag, emojiBaseData] = await getETagAndData(dataSource)
-  if (!eTag) {
-    // Handle lack of support for ETag or Access-Control-Expose-Headers
-    // https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Access-Control-Expose-Headers#Browser_compatibility
-    eTag = await jsonChecksum(emojiBaseData)
-  }
-
-  await loadData(db, emojiBaseData, dataSource, eTag)
-}
+import { loadDataForFirstTime, checkForUpdates } from './dataLoading'
 
 export default class Database {
   constructor ({ dataSource = DEFAULT_DATA_SOURCE, locale = DEFAULT_LOCALE, customEmoji = [] } = {}) {
@@ -177,15 +140,13 @@ export default class Database {
     }
   }
 
-  _clear () { // clear references to IDB, e.g. during a close event
+  // clear references to IDB, e.g. during a close event
+  _clear () {
     log('_clear database', this._dbName)
-    // Technically we don't need to call these functions because the memory leak tests
-    // prove we don't have leaks even with this code commented out. It's because
+    // We don't need to call removeEventListener or remove the manual "close" listeners.
+    // The memory leak tests prove this is unnecessary. It's because:
     // 1) IDBDatabases that can no longer fire "close" automatically have listeners GCed
     // 2) we clear the manual close listeners in databaseLifecycle.js.
-    // But I am paranoid about memory leaks, so I keep this code here.
-    this._db.removeEventListener('close', this._clear)
-    removeOnCloseListener(this._dbName, this._clear)
     this._db = this._ready = this._lazyUpdate = undefined
   }
 

src/database/dataLoading.js

@@ -0,0 +1,39 @@
+import { getETag, getETagAndData } from './utils/ajax'
+import { jsonChecksum } from './utils/jsonChecksum'
+import { hasData, loadData } from './idbInterface'
+import { log } from '../shared/log'
+
+export async function checkForUpdates (db, dataSource) {
+  // just do a simple HEAD request first to see if the eTags match
+  let emojiBaseData
+  let eTag = await getETag(dataSource)
+  if (!eTag) { // work around lack of ETag/Access-Control-Expose-Headers
+    const eTagAndData = await getETagAndData(dataSource)
+    eTag = eTagAndData[0]
+    emojiBaseData = eTagAndData[1]
+    if (!eTag) {
+      eTag = await jsonChecksum(emojiBaseData)
+    }
+  }
+  if (await hasData(db, dataSource, eTag)) {
+    log('Database already populated')
+  } else {
+    log('Database update available')
+    if (!emojiBaseData) {
+      const eTagAndData = await getETagAndData(dataSource)
+      emojiBaseData = eTagAndData[1]
+    }
+    await loadData(db, emojiBaseData, dataSource, eTag)
+  }
+}
+
+export async function loadDataForFirstTime (db, dataSource) {
+  let [eTag, emojiBaseData] = await getETagAndData(dataSource)
+  if (!eTag) {
+    // Handle lack of support for ETag or Access-Control-Expose-Headers
+    // https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Access-Control-Expose-Headers#Browser_compatibility
+    eTag = await jsonChecksum(emojiBaseData)
+  }
+
+  await loadData(db, emojiBaseData, dataSource, eTag)
+}

src/database/databaseLifecycle.js

@@ -70,9 +70,7 @@ export function closeDatabase (dbName) {
     const listeners = onCloseListeners[dbName]
     if (listeners) {
       for (const listener of listeners) {
-        try {
-          listener()
-        } catch (err) { /* ignore */ }
+        listener()
       }
     }
   }
@@ -98,13 +96,3 @@ export function addOnCloseListener (dbName, listener) {
   }
   listeners.push(listener)
 }
-
-export function removeOnCloseListener (dbName, listener) {
-  const listeners = onCloseListeners[dbName]
-  if (listeners) {
-    const idx = listeners.indexOf(listener)
-    if (idx !== -1) {
-      listeners.splice(idx, 1)
-    }
-  }
-}