Do a POW (Browser)

.gitignore

@@ -1,3 +1,4 @@
 /node_modules/
 /npm-debug.log
 /docs/
+/worker.browserify.js

.jshintignore

@@ -1,4 +1,5 @@
-node_modules
-test*
-karma*
-docs
+/node_modules/
+/test*
+/karma*
+/docs/
+/worker.browserify.js

.npmignore

@@ -1,5 +1,6 @@
-.travis.yml
-.jshint*
-karma*
-docs
-jsdoc.json
+/.travis.yml
+/.jshint*
+/karma*
+/docs/
+/jsdoc.json
+/worker.browserify.js

karma.conf.js

@@ -1,9 +1,11 @@
 process.env.CHROME_BIN = "chromium-browser";
 var allTests = !!process.env.ALL_TESTS;
 var files = ["test.js"];
-// Kludgy way to pass a variable to `test.js`.
 if (allTests) {
+  // Kludgy way to pass a variable to `test.js`.
   files.unshift("karma-all-tests.js");
+  // Worker code.
+  files.push({pattern: "worker.browserify.js", included: false});
 };
 
 module.exports = function(config) {
@@ -15,7 +17,7 @@ module.exports = function(config) {
 
     // frameworks to use
     // available frameworks: https://npmjs.org/browse/keyword/karma-adapter
-    frameworks: ["mocha", "browserify"],
+    frameworks: ["browserify", "mocha"],
 
 
     // list of files / patterns to load in the browser
@@ -73,6 +75,6 @@ module.exports = function(config) {
     singleRun: true,
 
 
-    browserNoActivityTimeout: allTests ? 60000 : 10000,
+    browserNoActivityTimeout: allTests ? 120000 : 10000,
   });
 };

lib/platform.browser.js

@@ -41,3 +41,82 @@ exports.getTarget = function(opts) {
   assert(target <= 9007199254740991, "Unsafe target");
   return target;
 };
+
+var FAILBACK_POOL_SIZE = 8;
+
+// NOTE(Kagami): We don't use promise shim in Browser implementation
+// because it's supported natively in new browsers (see
+// <http://caniuse.com/#feat=promises>) and we can use only new browsers
+// because of the WebCryptoAPI (see
+// <http://caniuse.com/#feat=cryptography>).
+exports.doPOW = function(opts) {
+  // Try to get native cores count then fallback to more or less
+  // reasonable value. See <https://stackoverflow.com/q/3289465> for
+  // details.
+  var poolSize = opts.poolSize || navigator.hardwareConcurrency;
+  poolSize = poolSize || FAILBACK_POOL_SIZE;
+
+  // Check all input params prematurely to not let promise executor or
+  // worker to fail because of it.
+  assert(poolSize > 0, "Bad pool size");
+  assert(opts.workerUrl, "Bad worker URL");
+  assert(typeof opts.target === "number", "Bad target");
+  assert(Buffer.isBuffer(opts.initialHash), "Bad initial hash");
+
+  var cancel;
+  var promise = new Promise(function(resolve, reject) {
+    function terminateAll() {
+      while (workers.length) {
+        workers.shift().terminate();
+      }
+    }
+
+    function onmessage(e) {
+      terminateAll();
+      if (e.data >= 0) {
+        resolve(e.data);
+      } else {
+        // It's very unlikely that execution will ever reach this place.
+        // Currently the only reason why Worker may return value less
+        // than zero is a 32-bit nonce overflow (see worker
+        // implementation). It's more than 4G double hashes.
+        reject();
+      }
+    }
+
+    function onerror(e) {
+      // XXX(Kagami): `onerror` events fires in Chrome even after all
+      // workers were terminated. It doesn't cause wrong behaviour but
+      // beware that this function may be executed several times.
+      terminateAll();
+      reject(e);
+    }
+
+    var workers = [];
+    var worker;
+    for (var i = 0; i < poolSize; i++) {
+      worker = new Worker(opts.workerUrl);
+      workers.push(worker);
+      // NOTE(Kagami): There is no race condition here. `onmessage` can
+      // only be called _after_ this for-loop finishes. See
+      // <https://stackoverflow.com/a/18192122> for details.
+      worker.onmessage = onmessage;
+      worker.onerror = onerror;
+      worker.postMessage({
+        num: i,
+        poolSize: poolSize,
+        target: opts.target,
+        initialHash: opts.initialHash,
+      });
+    }
+
+    cancel = function(e) {
+      terminateAll();
+      reject(e);
+    };
+  });
+  // Allow to stop POW via custom function added to the Promise
+  // instance.
+  promise.cancel = cancel;
+  return promise;
+};

lib/pow.js

@@ -3,9 +3,11 @@
  * @see {@link https://bitmessage.org/wiki/Proof_of_work}
  * @module bitmessage/pow
  */
+// TODO(Kagami): Find a way how to document object params properly.
 
 "use strict";
 
+var objectAssign = Object.assign || require("object-assign");
 var bmcrypto = require("./crypto");
 var platform = require("./platform");
 
@@ -17,7 +19,6 @@ var DEFAULT_EXTRA_BYTES = 1000;
  * @param {Object} opts - Target options
  * @return {number} Target.
  */
-// TODO(Kagami): Find a way how to document object params properly.
 // Just a wrapper around platform-specific implementation.
 exports.getTarget = function(opts) {
   var payloadLength = opts.payloadLength || opts.payload.length;
@@ -75,3 +76,20 @@ exports.check = function(opts) {
     return trialLo <= targetLo;
   }
 };
+
+/**
+ * Do a POW.
+ * @param {Object} opts - Proof of work options
+ * @return {Promise.<Buffer>} A promise that contains computed nonce for
+ * the given target when fulfilled.
+ */
+exports.do = function(opts) {
+  var initialHash;
+  if (opts.payload) {
+    initialHash = bmcrypto.sha512(opts.payload);
+  } else {
+    initialHash = opts.initialHash;
+  }
+  opts = objectAssign({}, opts, {initialHash: initialHash});
+  return platform.doPOW(opts);
+};

lib/worker.browser.js

@@ -0,0 +1,65 @@
+/**
+ * Web Worker routines for Browser platform.
+ */
+
+"use strict";
+
+// NOTE(Kagami): In order to use it you need to create separate
+// browserify bundle for this file, place it somewhere in your HTTP
+// server assets path (under the same origin with your application code)
+// and then pass appropriate `workerUrl` value to the function that
+// spawns workers.
+// You may also try to pass object URL instead. See
+// <http://mdn.io/worker.worker>, <https://stackoverflow.com/q/10343913>
+// for details.
+
+// XXX(Kagami): This is rather unpleasent that we use different SHA-2
+// implementations for main library code and for worker code (we use
+// `sha.js` here because it's faster). Though worker code lays in
+// separate file so it shouldn't result in any download overhead.
+var createHash = require("sha.js");
+
+function sha512(buf) {
+  return createHash("sha512").update(buf).digest();
+}
+
+function pow(opts) {
+  var nonce = opts.num;
+  var poolSize = opts.poolSize;
+  var message = new Buffer(72);
+  message.fill(0);
+  Buffer(opts.initialHash).copy(message, 8);
+  var targetHi = Math.floor(opts.target / 4294967296);
+  var targetLo = opts.target % 4294967296;
+  var digest, trialHi, trialLo;
+
+  while (true) {
+    // uint32_t overflow. There is no much need to fix it since 4G
+    // double hashes would we computed too long anyway in a Browser.
+    if (nonce > 4294967295) {
+      return -1;
+    }
+
+    message.writeUInt32BE(nonce, 4, true);
+    digest = sha512(sha512(message));
+    trialHi = digest.readUInt32BE(0, true);
+
+    if (trialHi > targetHi) {
+      nonce += poolSize;
+    } else if (trialHi === targetHi) {
+      trialLo = digest.readUInt32BE(4, true);
+      if (trialLo > targetLo) {
+        nonce += poolSize;
+      } else {
+        return nonce;
+      }
+    } else {
+      return nonce;
+    }
+  }
+}
+
+onmessage = function(e) {  // jshint ignore:line
+  var nonce = pow(e.data);
+  postMessage(nonce);  // jshint ignore:line
+};

package.json

@@ -7,11 +7,12 @@
     "./lib/platform.js": "./lib/platform.browser.js"
   },
   "scripts": {
-    "test": "ALL_TESTS=1 mocha && ALL_TESTS=1 xvfb-run -a karma start && jshint .",
+    "test": "ALL_TESTS=1 mocha && ALL_TESTS=1 npm run -s kc && ALL_TESTS=1 npm run -s kf && jshint .",
     "m": "mocha",
-    "k": "xvfb-run -a karma start",
-    "kc": "xvfb-run -a karma start --browsers Chromium",
-    "kf": "xvfb-run -a karma start --browsers Firefox",
+    "k": "npm run -s w && xvfb-run -a karma start",
+    "kc": "npm run -s w && xvfb-run -a karma start --browsers Chromium",
+    "kf": "npm run -s w && xvfb-run -a karma start --browsers Firefox",
+    "w": "browserify lib/worker.browser.js > worker.browserify.js",
     "j": "jshint .",
     "d": "jsdoc -c jsdoc.json",
     "mv-docs": "rm -rf docs && jsdoc -c jsdoc.json && D=`mktemp -d` && mv docs \"$D\" && git checkout gh-pages && rm -rf docs && mv \"$D/docs\" . && rm -rf \"$D\""
@@ -33,14 +34,15 @@
   },
   "homepage": "https://github.com/bitchan/bitmessage",
   "devDependencies": {
+    "browserify": "^8.1.0",
     "chai": "*",
     "jsdoc": "^3.3.0-alpha13",
     "jshint": "*",
-    "karma": "^0.12.28",
-    "karma-browserify": "^1.0.1",
+    "karma": "^0.12.31",
+    "karma-browserify": "^2.0.0",
     "karma-chrome-launcher": "^0.1.7",
     "karma-cli": "~0.0.4",
-    "karma-firefox-launcher": "^0.1.3",
+    "karma-firefox-launcher": "^0.1.4",
     "karma-mocha": "^0.1.10",
     "karma-mocha-reporter": "^0.3.1",
     "mocha": "*"

test.js

@@ -278,6 +278,16 @@ describe("POW", function() {
     expect(POW.check({nonce: 3122437, target: 4864647698763, initialHash: Buffer("8ff2d685db89a0af2e3dbfd3f700ae96ef4d9a1eac72fd778bbb368c7510cddda349e03207e1c4965bd95c6f7265e8f1a481a08afab3874eaafb9ade09a10880", "hex")})).to.be.true;
     expect(POW.check({nonce: 3122436, target: 4864647698763, initialHash: Buffer("8ff2d685db89a0af2e3dbfd3f700ae96ef4d9a1eac72fd778bbb368c7510cddda349e03207e1c4965bd95c6f7265e8f1a481a08afab3874eaafb9ade09a10880", "hex")})).to.be.false;
   });
+
+  if (allTests && typeof window !== "undefined") {
+    it("should do a POW", function() {
+      this.timeout(120000);
+      return POW.do({workerUrl: "/base/worker.browserify.js", target: 10693764680411, initialHash: Buffer("8ff2d685db89a0af2e3dbfd3f700ae96ef4d9a1eac72fd778bbb368c7510cddda349e03207e1c4965bd95c6f7265e8f1a481a08afab3874eaafb9ade09a10880", "hex")})
+        .then(function(nonce) {
+          expect(nonce).to.equal(2373146);
+        });
+    });
+  }
 });
 
 describe("High-level classes", function() {
@@ -317,7 +327,7 @@ describe("High-level classes", function() {
     // very slow. This need to be fixed.
     if (allTests && typeof window === "undefined") {
       it("should allow to generate shorter address", function() {
-        this.timeout(60000);
+        this.timeout(120000);
         var addr = Address.fromRandom({ripelen: 18});
         var ripe = addr.getRipe({short: true});
         expect(ripe.length).to.be.at.most(18);