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cache.js
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cache.js
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var dbPromise;
var canUseCache =
// The server doesn't benefit from dynamic module fetching, and almost
// certainly doesn't support IndexedDB.
Meteor.isClient &&
// Cordova bundles all modules into the monolithic initial bundle, so
// the dynamic module cache won't be necessary.
! Meteor.isCordova &&
// Caching can be confusing in development, and is designed to be a
// transparent optimization for production performance.
Meteor.isProduction;
function getIDB() {
if (typeof indexedDB !== "undefined") return indexedDB;
if (typeof webkitIndexedDB !== "undefined") return webkitIndexedDB;
if (typeof mozIndexedDB !== "undefined") return mozIndexedDB;
if (typeof OIndexedDB !== "undefined") return OIndexedDB;
if (typeof msIndexedDB !== "undefined") return msIndexedDB;
}
function withDB(callback) {
dbPromise = dbPromise || new Promise(function (resolve, reject) {
var idb = getIDB();
if (! idb) {
throw new Error("IndexedDB not available");
}
// Incrementing the version number causes all existing object stores
// to be deleted and recreates those specified by objectStoreMap.
var request = idb.open("MeteorDynamicImportCache", 2);
request.onupgradeneeded = function (event) {
var db = event.target.result;
// It's fine to delete existing object stores since onupgradeneeded
// is only called when we change the DB version number, and the data
// we're storing is disposable/reconstructible.
Array.from(db.objectStoreNames).forEach(db.deleteObjectStore, db);
Object.keys(objectStoreMap).forEach(function (name) {
db.createObjectStore(name, objectStoreMap[name]);
});
};
request.onerror = makeOnError(reject, "indexedDB.open");
request.onsuccess = function (event) {
resolve(event.target.result);
};
});
return dbPromise.then(callback, function (error) {
return callback(null);
});
}
var objectStoreMap = {
sourcesByVersion: { keyPath: "version" }
};
function makeOnError(reject, source) {
return function (event) {
reject(new Error(
"IndexedDB failure in " + source + " " +
JSON.stringify(event.target)
));
// Returning true from an onerror callback function prevents an
// InvalidStateError in Firefox during Private Browsing. Silencing
// that error is safe because we handle the error more gracefully by
// passing it to the Promise reject function above.
// https://github.com/meteor/meteor/issues/8697
return true;
};
}
var checkCount = 0;
exports.checkMany = function (versions) {
var ids = Object.keys(versions);
var sourcesById = Object.create(null);
// Initialize sourcesById with null values to indicate all sources are
// missing (unless replaced with actual sources below).
ids.forEach(function (id) {
sourcesById[id] = null;
});
if (! canUseCache) {
return Promise.resolve(sourcesById);
}
return withDB(function (db) {
if (! db) {
// We thought we could used IndexedDB, but something went wrong
// while opening the database, so err on the side of safety.
return sourcesById;
}
var txn = db.transaction([
"sourcesByVersion"
], "readonly");
var sourcesByVersion = txn.objectStore("sourcesByVersion");
++checkCount;
function finish() {
--checkCount;
return sourcesById;
}
return Promise.all(ids.map(function (id) {
return new Promise(function (resolve, reject) {
var version = versions[id];
if (version) {
var sourceRequest = sourcesByVersion.get(version);
sourceRequest.onerror = makeOnError(reject, "sourcesByVersion.get");
sourceRequest.onsuccess = function (event) {
var result = event.target.result;
if (result) {
sourcesById[id] = result.source;
}
resolve();
};
} else resolve();
});
})).then(finish, finish);
});
};
var pendingVersionsAndSourcesById = Object.create(null);
exports.setMany = function (versionsAndSourcesById) {
if (canUseCache) {
Object.assign(
pendingVersionsAndSourcesById,
versionsAndSourcesById
);
// Delay the call to flushSetMany so that it doesn't contribute to the
// amount of time it takes to call module.dynamicImport.
if (! flushSetMany.timer) {
flushSetMany.timer = setTimeout(flushSetMany, 100);
}
}
};
function flushSetMany() {
if (checkCount > 0) {
// If checkMany is currently underway, postpone the flush until later,
// since updating the cache is less important than reading from it.
return flushSetMany.timer = setTimeout(flushSetMany, 100);
}
flushSetMany.timer = null;
var versionsAndSourcesById = pendingVersionsAndSourcesById;
pendingVersionsAndSourcesById = Object.create(null);
return withDB(function (db) {
if (! db) {
// We thought we could used IndexedDB, but something went wrong
// while opening the database, so err on the side of safety.
return;
}
var setTxn = db.transaction([
"sourcesByVersion"
], "readwrite");
var sourcesByVersion = setTxn.objectStore("sourcesByVersion");
return Promise.all(
Object.keys(versionsAndSourcesById).map(function (id) {
var info = versionsAndSourcesById[id];
return new Promise(function (resolve, reject) {
var request = sourcesByVersion.put({
version: info.version,
source: info.source
});
request.onerror = makeOnError(reject, "sourcesByVersion.put");
request.onsuccess = resolve;
});
})
);
});
}