Set machine

README.md

@@ -62,6 +62,13 @@ This diverges from [bson](https://github.com/mongodb/js-bson)'s implementation w
 
 **returns** a valid 24 character `ObjectID` hex string.
 
+### ObjectID.setMachineID(number)<br>ObjectID.setMachineID(string)
+You can use this to set a custom machine-id.
+It should be a 6 character hex string or a 3 byte integer and will truncate all larger values.
+
+### ObjectID.getMachineID()
+**returns** the machine-id as a 3 byte int.
+
 ## Test
     mocha
 

objectid.js

@@ -101,6 +101,47 @@ ObjectID.isValid = function(objectid) {
   return /^[0-9A-F]{24}$/i.test(objectid.toString());
 };
 
+/**
+ * set a custom machineID
+ * 
+ * @param {String|Number} machineid Can be a string, hex-string or a number
+ * @return {void}
+ * @api public
+ */
+ObjectID.setMachineID = function(arg) {
+  var machineID;
+
+  if(typeof arg === "string") {
+    // hex string
+    machineID = parseInt(arg, 16);
+
+    // any string
+    if(isNaN(machineID)) {
+      arg = ('000000' + arg).substr(-7,6);
+
+      machineID = "";
+      for(var i = 0;i<6; i++) {
+        machineID += (arg.charCodeAt(i));
+      }
+    }
+  }
+  else if(/number|undefined/.test(typeof arg)) {
+    machineID = arg | 0;
+  }
+
+  MACHINE_ID = (machineID & 0xFFFFFF);
+}
+
+/**
+ * get the machineID
+ * 
+ * @return {number}
+ * @api public
+ */
+ObjectID.getMachineID = function() {
+  return MACHINE_ID;
+}
+
 ObjectID.prototype = {
   _bsontype: 'ObjectID',
   constructor: ObjectID,

package.json

@@ -28,6 +28,7 @@
   },
   "homepage": "https://github.com/williamkapke/bson-objectid",
   "devDependencies": {
+    "mocha": "^3.5.3",
     "should": "^4.1.0"
   }
 }

test/test.js

@@ -143,5 +143,36 @@ describe("ObjectIDs", function() {
     }).should.throw();
   });
 
+  it("should should set/get a custom machineID", function() {
+    var tests = [
+      { machineID: 0x1,                 expected: 0x000001 }, // short
+      { machineID: 0x123456,            expected: 0x123456 }, // exact
+      { machineID: 0x0987654321,        expected: 0x654321 }, // long
+
+      { machineID: 'TIZÙL“G!íçm',      expected: 0xe41e05 }, // any string
+
+      { machineID: '01',            expected: 0x000001 }, // short hex string
+      { machineID: '01a2b3',        expected: 0x01a2b3 }, // exact hex string
+      { machineID: '7f6e5d4c3b2a0', expected: 0xc3b2a0 }, // long hex string
+    ];
+
+    tests.forEach(function(test) {
+      ObjectID.setMachineID(test.machineID);
+
+      ObjectID.getMachineID().should.eql(test.expected);
+    });
+  });
+
+  it("should work with a specific machineID", function() {
+    var testPattern = /^([0-9a-f]{8})([0-9a-f]{6})([0-9a-f]{4})([0-9a-f]{6})$/i;
+
+    var mid = parseInt(Math.random() * 0xFFFFFF, 10);
+    ObjectID.setMachineID(mid);
+
+    var o = ObjectID.generate();
+    var result = o.match(testPattern);
+
+    result[2].should.eql(mid.toString(16));
+  });
 });