feat(info): cache ytdl.getInfo() calls to the same videos

A 1 second cache, located in `ytdl.cache.info` has been introduced
for calls to `ytdl.getInfo()` to help with the case of
calling it, and then downloading the video with `ytdl()`,
which uses `ytdl.getInfo()` internally.

closes #331, closes #332
BREAKING CHANGES:
- ytdl.cache -> ytdl.cache.sig

lib/index.js

@@ -15,7 +15,7 @@ const parseTime   = require('m3u8stream/lib/parse-time');
  */
 const ytdl = module.exports = function ytdl(link, options) {
   const stream = createStream(options);
-  getInfo(link, options, (err, info) => {
+  ytdl.getInfo(link, options, (err, info) => {
     if (err) {
       stream.emit('error', err);
       return;
@@ -27,8 +27,6 @@ const ytdl = module.exports = function ytdl(link, options) {
   return stream;
 };
 
-
-ytdl.getInfo = getInfo;
 ytdl.chooseFormat = util.chooseFormat;
 ytdl.filterFormats = util.filterFormats;
 ytdl.validateID = util.validateID;
@@ -37,7 +35,52 @@ ytdl.validateLink = deprecate(util.validateURL,
   'ytdl.validateLink: Renamed to ytdl.validateURL');
 ytdl.getURLVideoID = util.getURLVideoID;
 ytdl.getVideoID = util.getVideoID;
-ytdl.cache = sig.cache;
+ytdl.cache = {
+  sig: sig.cache,
+  info: new Map(),
+};
+
+
+/**
+ * Cached version of `getInfo()`
+ * In case a user wants to get a video's info before downloading.
+ *
+ * @param {String} link
+ * @param {Object} options
+ * @param {Function(Error, Object)} callback
+ */
+ytdl.getInfo = (link, options, callback) => {
+  if (typeof options === 'function') {
+    callback = options;
+    options = {};
+  } else if (!options) {
+    options = {};
+  }
+
+  if (!callback) {
+    return new Promise((resolve, reject) => {
+      ytdl.getInfo(link, options, (err, info) => {
+        if (err) return reject(err);
+        resolve(info);
+      });
+    });
+  }
+
+  const id = util.getVideoID(link);
+  if (id instanceof Error) return callback(id);
+
+  const key = [id, options.lang].join('-');
+  if (ytdl.cache.info.has(key)) {
+    callback(null, ytdl.cache.info.get(key));
+  } else {
+    getInfo(id, options, (err, info) => {
+      if (err) return callback(err);
+      ytdl.cache.info.set(key, info);
+      setTimeout(() => { ytdl.cache.info.delete(key); }, 1000);
+      callback(null, info);
+    });
+  }
+};
 
 
 function createStream(options) {

lib/info.js

@@ -23,29 +23,11 @@ const KEYS_TO_SPLIT = [
 /**
  * Gets info from a video.
  *
- * @param {String} link
+ * @param {String} id
  * @param {Object} options
  * @param {Function(Error, Object)} callback
  */
-module.exports = function getInfo(link, options, callback) {
-  if (typeof options === 'function') {
-    callback = options;
-    options = {};
-  } else if (!options) {
-    options = {};
-  }
-  if (!callback) {
-    return new Promise((resolve, reject) => {
-      getInfo(link, options, (err, info) => {
-        if (err) return reject(err);
-        resolve(info);
-      });
-    });
-  }
-
-  const id = util.getVideoID(link);
-  if (id instanceof Error) return callback(id);
-
+module.exports = function getInfo(id, options, callback) {
   // Try getting config from the video page first.
   const params = 'hl=' + (options.lang || 'en');
   let url = VIDEO_URL + id + '&' + params;

test/download-test.js

@@ -3,7 +3,7 @@ const path        = require('path');
 const fs          = require('fs');
 const url         = require('url');
 const streamEqual = require('stream-equal');
-const spy         = require('sinon').spy;
+const sinon       = require('sinon');
 const nock        = require('./nock');
 const ytdl        = require('..');
 
@@ -24,9 +24,9 @@ describe('Download video', () => {
     });
   });
 
-  beforeEach(() => {
-    ytdl.cache.clear();
-  });
+  let clock;
+  before(() => { clock = sinon.useFakeTimers({ toFake: ['setTimeout'] }); });
+  after(() => { clock.restore(); });
 
   it('Should be pipeable and data equal to stored file', (done) => {
     const scope = nock(id, {
@@ -113,7 +113,7 @@ describe('Download video', () => {
         stream.on('data', () => {
           throw new Error('Should not emit `data`');
         });
-        const abort = spy();
+        const abort = sinon.spy();
         stream.on('abort', abort);
         stream.on('error', (err) => {
           scope.done();
@@ -145,7 +145,7 @@ describe('Download video', () => {
           });
         });
 
-        const abort = spy();
+        const abort = sinon.spy();
         stream.on('abort', abort);
         stream.on('error', (err) => {
           scope.done();

test/info-test.js

@@ -3,14 +3,14 @@ const path   = require('path');
 const fs     = require('fs');
 const assert = require('assert-diff');
 const nock   = require('./nock');
-const spy    = require('sinon').spy;
+const sinon = require('sinon');
 const muk    = require('muk-prop');
 
 
 describe('ytdl.getInfo()', () => {
-  beforeEach(() => {
-    ytdl.cache.clear();
-  });
+  let clock;
+  before(() => { clock = sinon.useFakeTimers({ toFake: ['setTimeout'] }); });
+  after(() => { clock.restore(); });
 
   describe('From a regular video', () => {
     const id = 'pJk0p-98Xzc';
@@ -112,6 +112,33 @@ describe('ytdl.getInfo()', () => {
         });
       });
     });
+
+    describe('Called twice', () => {
+      const id = 'pJk0p-98Xzc';
+
+      it('Only makes requests once', (done) => {
+        const scope = nock(id, {
+          type: 'vevo',
+          dashmpd: true,
+          get_video_info: true,
+          player: 'player-en_US-vflV3n15C',
+        });
+
+        let myinfo = null;
+        ytdl.getInfo(id, (err, info) => {
+          assert.ifError(err);
+          myinfo = info;
+          assert.ok(info.description.length);
+          assert.equal(info.formats.length, expectedInfo.formats.length);
+          ytdl.getInfo(id, (err, info) => {
+            assert.ifError(err);
+            scope.done();
+            assert.equal(info, myinfo);
+            done();
+          });
+        });
+      });
+    });
   });
 
   describe('From a non-existant video', () => {
@@ -381,7 +408,7 @@ describe('ytdl.getInfo()', () => {
 
   describe('When encountering a format not yet known with debug', () => {
     it('Warns the console', (done) => {
-      const warn = spy();
+      const warn = sinon.spy();
       muk(console, 'warn', warn);
       after(muk.restore);
 

test/irl-test.js

@@ -19,7 +19,8 @@ describe('Try downloading videos without mocking', () => {
   beforeEach(() => {
     nock.cleanAll();
     nock.enableNetConnect();
-    ytdl.cache.clear();
+    ytdl.cache.sig.clear();
+    ytdl.cache.info.clear();
   });
 
   Object.keys(videos).forEach((desc) => {

test/nock.js

@@ -1,6 +1,7 @@
-const path = require('path');
-const url  = require('url');
-const nock = require('nock');
+const ytdl   = require('..');
+const path  = require('path');
+const url   = require('url');
+const nock  = require('nock');
 
 const YT_HOST       = 'https://www.youtube.com';
 const VIDEO_PATH    = '/watch?v=';
@@ -13,6 +14,12 @@ const INFO_PATH     = '/get_video_info?';
 before(() => { nock.disableNetConnect(); });
 after(() => { nock.enableNetConnect(); });
 
+beforeEach(() => {
+  ytdl.cache.sig.clear();
+  ytdl.cache.info.clear();
+});
+
+
 exports = module.exports = (id, opts) => {
   opts = opts || {};
   let scopes = [];

test/sig-test.js

@@ -26,10 +26,16 @@ describe('Get tokens', () => {
 
   describe('Hit the same video twice', () => {
     it('Gets html5player tokens from cache', (done) => {
-      sig.getTokens(url, {}, (err, tokens) => {
+      const scope = nock.url(url).replyWithFile(200, filepath);
+      sig.getTokens(url, true, (err, tokens) => {
         assert.ifError(err);
+        scope.done();
         assert.ok(tokens.length);
-        done();
+        sig.getTokens(url, {}, (err, tokens) => {
+          assert.ifError(err);
+          assert.ok(tokens.length);
+          done();
+        });
       });
     });
   });