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build/node_modules/sw-toolbox/lib/idb-cache-expiration.js

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+/*
+ Copyright 2015 Google Inc. All Rights Reserved.
+
+ Licensed under the Apache License, Version 2.0 (the "License");
+ you may not use this file except in compliance with the License.
+ You may obtain a copy of the License at
+
+     http://www.apache.org/licenses/LICENSE-2.0
+
+ Unless required by applicable law or agreed to in writing, software
+ distributed under the License is distributed on an "AS IS" BASIS,
+ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ See the License for the specific language governing permissions and
+ limitations under the License.
+*/
+'use strict';
+
+var DB_PREFIX = 'sw-toolbox-';
+var DB_VERSION = 1;
+var STORE_NAME = 'store';
+var URL_PROPERTY = 'url';
+var TIMESTAMP_PROPERTY = 'timestamp';
+var cacheNameToDbPromise = {};
+
+function openDb(cacheName) {
+  return new Promise(function(resolve, reject) {
+    var request = indexedDB.open(DB_PREFIX + cacheName, DB_VERSION);
+
+    request.onupgradeneeded = function() {
+      var objectStore = request.result.createObjectStore(STORE_NAME,
+          {keyPath: URL_PROPERTY});
+      objectStore.createIndex(TIMESTAMP_PROPERTY, TIMESTAMP_PROPERTY,
+          {unique: false});
+    };
+
+    request.onsuccess = function() {
+      resolve(request.result);
+    };
+
+    request.onerror = function() {
+      reject(request.error);
+    };
+  });
+}
+
+function getDb(cacheName) {
+  if (!(cacheName in cacheNameToDbPromise)) {
+    cacheNameToDbPromise[cacheName] = openDb(cacheName);
+  }
+
+  return cacheNameToDbPromise[cacheName];
+}
+
+function setTimestampForUrl(db, url, now) {
+  return new Promise(function(resolve, reject) {
+    var transaction = db.transaction(STORE_NAME, 'readwrite');
+    var objectStore = transaction.objectStore(STORE_NAME);
+    objectStore.put({url: url, timestamp: now});
+
+    transaction.oncomplete = function() {
+      resolve(db);
+    };
+
+    transaction.onabort = function() {
+      reject(transaction.error);
+    };
+  });
+}
+
+function expireOldEntries(db, maxAgeSeconds, now) {
+  // Bail out early by resolving with an empty array if we're not using
+  // maxAgeSeconds.
+  if (!maxAgeSeconds) {
+    return Promise.resolve([]);
+  }
+
+  return new Promise(function(resolve, reject) {
+    var maxAgeMillis = maxAgeSeconds * 1000;
+    var urls = [];
+
+    var transaction = db.transaction(STORE_NAME, 'readwrite');
+    var objectStore = transaction.objectStore(STORE_NAME);
+    var index = objectStore.index(TIMESTAMP_PROPERTY);
+
+    index.openCursor().onsuccess = function(cursorEvent) {
+      var cursor = cursorEvent.target.result;
+      if (cursor) {
+        if (now - maxAgeMillis > cursor.value[TIMESTAMP_PROPERTY]) {
+          var url = cursor.value[URL_PROPERTY];
+          urls.push(url);
+          objectStore.delete(url);
+          cursor.continue();
+        }
+      }
+    };
+
+    transaction.oncomplete = function() {
+      resolve(urls);
+    };
+
+    transaction.onabort = reject;
+  });
+}
+
+function expireExtraEntries(db, maxEntries) {
+  // Bail out early by resolving with an empty array if we're not using
+  // maxEntries.
+  if (!maxEntries) {
+    return Promise.resolve([]);
+  }
+
+  return new Promise(function(resolve, reject) {
+    var urls = [];
+
+    var transaction = db.transaction(STORE_NAME, 'readwrite');
+    var objectStore = transaction.objectStore(STORE_NAME);
+    var index = objectStore.index(TIMESTAMP_PROPERTY);
+
+    var countRequest = index.count();
+    index.count().onsuccess = function() {
+      var initialCount = countRequest.result;
+
+      if (initialCount > maxEntries) {
+        index.openCursor().onsuccess = function(cursorEvent) {
+          var cursor = cursorEvent.target.result;
+          if (cursor) {
+            var url = cursor.value[URL_PROPERTY];
+            urls.push(url);
+            objectStore.delete(url);
+            if (initialCount - urls.length > maxEntries) {
+              cursor.continue();
+            }
+          }
+        };
+      }
+    };
+
+    transaction.oncomplete = function() {
+      resolve(urls);
+    };
+
+    transaction.onabort = reject;
+  });
+}
+
+function expireEntries(db, maxEntries, maxAgeSeconds, now) {
+  return expireOldEntries(db, maxAgeSeconds, now).then(function(oldUrls) {
+    return expireExtraEntries(db, maxEntries).then(function(extraUrls) {
+      return oldUrls.concat(extraUrls);
+    });
+  });
+}
+
+module.exports = {
+  getDb: getDb,
+  setTimestampForUrl: setTimestampForUrl,
+  expireEntries: expireEntries
+};