Merge pull request #122 from sachaaaaa/consolidateLists

Add logic to consolidate list of data returned by different snodes

Gruntfile.js

@@ -100,7 +100,10 @@ module.exports = grunt => {
         dest: 'js/libtextsecure.js',
       },
       libloki: {
-        src: ['libloki/libloki-protocol.js'],
+        src: [
+          'libloki/libloki-protocol.js',
+          'libloki/service_nodes.js',
+        ],
         dest: 'js/libloki.js',
       },
       lokitest: {

libloki/service_nodes.js

@@ -0,0 +1,35 @@
+/* global window */
+
+// eslint-disable-next-line func-names
+(function () {
+  window.libloki = window.libloki || {};
+  window.libloki.serviceNodes = window.libloki.serviceNodes || {};
+
+  function consolidateLists(lists, threshold = 1){
+    if (typeof threshold !== 'number') {
+      throw Error('Provided threshold is not a number');
+    }
+
+    // calculate list size manually since `Set`
+    // does not have a `length` attribute
+    let numLists = 0;
+    const occurences = {};
+    lists.forEach(list => {
+      numLists += 1;
+      list.forEach(item => {
+        if (!(item in occurences)) {
+          occurences[item] = 1;
+        } else {
+          occurences[item] += 1;
+        }
+      });
+    });
+
+    const scaledThreshold = numLists * threshold;
+    return Object.entries(occurences)
+      .filter(keyValue => keyValue[1] >= scaledThreshold)
+      .map(keyValue => keyValue[0]);
+  }
+
+  window.libloki.serviceNodes.consolidateLists = consolidateLists;
+})();

libloki/test/index.html

@@ -25,9 +25,11 @@
   <script type="text/javascript" src="../../libtextsecure/stringview.js" data-cover></script>
 
   <script type="text/javascript" src="../libloki-protocol.js" data-cover></script>
+  <script type="text/javascript" src="../service_nodes.js" data-cover></script>
 
   <script type="text/javascript" src="proof-of-work_test.js"></script>
   <script type="text/javascript" src="libloki-protocol_test.js"></script>
+  <script type="text/javascript" src="service_nodes_test.js"></script>
 
   <!-- Comment out to turn off code coverage. Useful for getting real callstacks. -->
   <!--   NOTE: blanket doesn't support modern syntax and will choke until we find a replacement. :0( -->

libloki/test/service_nodes_test.js

@@ -0,0 +1,57 @@
+/* global libloki, chai */
+
+describe('ServiceNodes', () => {
+  describe('#consolidateLists', () => {
+    it('should throw when provided a non-iterable list', () => {
+      chai.expect(() => libloki.serviceNodes.consolidateLists(null, 1)).to.throw();
+    });
+    it('should throw when provided a non-iterable item in the list', () => {
+      chai.expect(() => libloki.serviceNodes.consolidateLists([1, 2, 3], 1)).to.throw();
+    });
+    it('should throw when provided a non-number threshold', () => {
+      chai.expect(() => libloki.serviceNodes.consolidateLists([], 'a')).to.throw();
+    });
+    it('should return an empty array when the input is an empty array', () => {
+      const result = libloki.serviceNodes.consolidateLists([]);
+      chai.expect(result).to.deep.equal([]);
+    });
+    it('should return the input when only 1 list is provided', () => {
+      const result = libloki.serviceNodes.consolidateLists([['a', 'b', 'c']]);
+      chai.expect(result).to.deep.equal(['a', 'b', 'c']);
+    });
+    it('should return the union of all lists when threshold is 0', () => {
+      const result = libloki.serviceNodes.consolidateLists([
+        ['a', 'b', 'c', 'h'],
+        ['d', 'e', 'f', 'g'],
+        ['g', 'h'],
+      ], 0);
+      chai.expect(result.sort()).to.deep.equal(['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h']);
+    });
+    it('should return the intersection of all lists when threshold is 1', () => {
+      const result = libloki.serviceNodes.consolidateLists([
+        ['a', 'b', 'c', 'd'],
+        ['a', 'e', 'f', 'g'],
+        ['a', 'h'],
+      ], 1);
+      chai.expect(result).to.deep.equal(['a']);
+    });
+    it('should return the elements that have an occurence >= the provided threshold', () => {
+      const result = libloki.serviceNodes.consolidateLists([
+        ['a', 'b', 'c', 'd', 'e', 'f', 'g'],
+        ['a', 'b', 'c', 'd', 'e', 'f', 'h'],
+        ['a', 'b', 'c', 'd', 'e', 'f', 'g'],
+        ['a', 'b', 'c', 'd', 'e', 'g', 'h'],
+      ], 3/4);
+      chai.expect(result).to.deep.equal(['a', 'b', 'c', 'd', 'e', 'f', 'g']);
+    });
+    it('should work with sets as well', () => {
+      const result = libloki.serviceNodes.consolidateLists(new Set([
+        new Set(['a', 'b', 'c', 'd', 'e', 'f', 'g']),
+        new Set(['a', 'b', 'c', 'd', 'e', 'f', 'h']),
+        new Set(['a', 'b', 'c', 'd', 'e', 'f', 'g']),
+        new Set(['a', 'b', 'c', 'd', 'e', 'g', 'h']),
+      ]), 3/4);
+      chai.expect(result).to.deep.equal(['a', 'b', 'c', 'd', 'e', 'f', 'g']);
+    });
+  });
+});