Support time discretization in scripts

This can be used to ensure parameter refresh times are aligned (as
opposed to using Date.now() - X). It also allows for possible future
optimizations by exploiting the fact that the value of Date.now(X)
remains static for a given amount of time.

The variance value can be used to shift the discretization threshold
points based on the hash of the device ID for load distribution.

The djb2 hashing algorithm has been replaced with MD5 for better
distribution.

lib/common.coffee

@@ -18,7 +18,6 @@
 ###
 
 buffer = require 'buffer'
-querystring = require 'querystring'
 
 UNDEFINED_TYPE = '[object Undefined]'
 NULL_TYPE = '[object Null]'
@@ -224,14 +223,6 @@ escapeRegExp = (str) ->
   return str.replace(/[\-\[\]\/\{\}\(\)\*\+\?\.\\\^\$\|]/g, "\\$&")
 
 
-# djb2 hashing algorithm adapted from http://www.cse.yorku.ca/~oz/hash.html
-djb2 = (str) ->
-  hash = 5381
-  for i in [0...str.length]
-    hash = ((hash << 5) + hash) ^ str.charCodeAt(i)
-  return hash
-
-
 exports.UNDEFINED_TYPE = UNDEFINED_TYPE
 exports.NULL_TYPE = NULL_TYPE
 exports.NUMBER_TYPE = NUMBER_TYPE
@@ -246,4 +237,3 @@ exports.parsePath = parsePath
 exports.addPathMeta = addPathMeta
 exports.hammingWeight = hammingWeight
 exports.escapeRegExp = escapeRegExp
-exports.djb2 = djb2

lib/cwmp.coffee

@@ -31,6 +31,8 @@ cache = require './cache'
 localCache = require './local-cache'
 db = require './db'
 logger = require './logger'
+scheduling = require './scheduling'
+
 
 MAX_CYCLES = 4
 
@@ -198,28 +200,6 @@ transferComplete = (sessionContext, rpc) ->
   )
 
 
-testSchedule = (schedule, timestamp) ->
-  range = schedule.schedule.nextRange(10, new Date(timestamp))
-  prev = schedule.schedule.prevRange(1, new Date(timestamp), new Date(timestamp - schedule.duration))
-
-  if prev
-    first = +(prev[0] ? 0)
-    last = +(prev[1] ? 0) + schedule.duration
-  else
-    first = +(range[0][0] ? 0)
-    last = +(range[0][1] ? 0) + schedule.duration
-
-  for r in range
-    if last < r[0]
-      break
-    last = +(r[1] ? 0) + schedule.duration
-
-  if timestamp >= first
-    return [true, Math.max(0, last - timestamp)]
-  else
-    return [false, first - timestamp]
-
-
 # Append providions and remove duplicates
 appendProvisions = (original, toAppend) ->
   modified = false
@@ -293,8 +273,13 @@ applyPresets = (sessionContext) ->
           eventsMatch = false
           break
 
-      continue if (not eventsMatch) or (preset.schedule and not
+      continue if not eventsMatch
-        (preset.schedule.schedule and testSchedule(preset.schedule, sessionContext.timestamp)[0]))
+
+      if preset.schedule
+        continue if not preset.schedule.schedule
+        r = scheduling.cron(sessionContext.timestamp, preset.schedule.schedule)
+        if not (r[0] + preset.schedule.duration > sessionContext.timestamp)
+          continue
 
       filteredPresets.push(preset)
       for k of preset.precondition

lib/default-provisions.js

@@ -21,6 +21,7 @@
 const config = require("./config");
 const common = require("./common");
 const device = require("./device");
+const scheduling = require("./scheduling");
 
 const MAX_DEPTH = config.get("MAX_DEPTH");
 
@@ -31,8 +32,8 @@ function refresh(sessionContext, provision, declarations, startRevision, endRevi
   path.length = MAX_DEPTH;
   path.fill("*", l);
   let every = 1000 * (provision[2] || 1);
-  let offset = Math.abs(common.djb2(sessionContext.deviceId)) % 86400000;
+  let offset = scheduling.variance(sessionContext.deviceId, every);
-  let t = Math.trunc((sessionContext.timestamp + offset) / every) * every - offset;
+  let t = scheduling.interval(sessionContext.timestamp, every, offset);
 
   for (let i = l; i < path.length; ++ i)
     declarations.push([path.slice(0, i), t, {object: 1, writable: 1, value: t}]);

lib/local-cache.js

@@ -21,12 +21,11 @@
 const vm = require("vm");
 const crypto = require("crypto");
 
-const later = require("later");
-
 const db = require("./db");
 const cache = require("./cache");
 const query = require("./query");
 const logger = require("./logger");
+const scheduling = require("./scheduling");
 
 const REFRESH = 3000;
 
@@ -125,11 +124,7 @@ function refresh(callback) {
 
               try {
                 schedule.duration = +(parts.shift()) * 1000;
-                if (parts.length === 5) {
+                schedule.schedule = scheduling.parseCron(parts.join(" "));
-                  parts.unshift("0");
-                  // TODO later.js doesn't throw erorr if expression is invalid!
-                  schedule.schedule = later.schedule(later.parse.cron(parts.join(" "), true));
-                }
               }
               catch (err) {
                 logger.warn({

lib/sandbox.js

@@ -26,6 +26,7 @@ const common = require("./common");
 const device = require("./device");
 const extensions = require("./extensions");
 const logger = require("./logger");
+const scheduling = require("./scheduling");
 
 
 // Used for throwing to exit user script and commit
@@ -40,15 +41,39 @@ let state;
 
 
 class SandboxDate {
-  constructor(arg) {
+  constructor() {
     if (arguments.length)
-      return new (Function.prototype.bind.apply(Date, arguments));
+      return new Date(...arguments);
 
     return new Date(state.sessionContext.timestamp);
   }
 
-  static now() {
+  static now(intervalOrCron, variance) {
-    return state.sessionContext.timestamp;
+    let t = state.sessionContext.timestamp;
+
+    if (typeof intervalOrCron === "number") {
+
+      if (variance == null)
+        variance = intervalOrCron;
+
+      let offset = 0;
+      if (variance)
+        offset = scheduling.variance(state.sessionContext.deviceId, variance);
+
+      t = scheduling.interval(t, intervalOrCron, offset);
+    }
+    else if (typeof intervalOrCron === "string") {
+      let offset = 0;
+      if (variance)
+        offset = scheduling.variance(state.sessionContext.deviceId, variance);
+      let cron = scheduling.parseCron(intervalOrCron);
+      t = scheduling.cron(t, cron, offset)[0];
+    }
+    else if (intervalOrCron) {
+      throw new Error("Invalid Date.now() argument");
+    }
+
+    return t;
   }
 };
 

lib/scheduling.js

@@ -0,0 +1,78 @@
+/**
+ * Copyright 2013-2017  Zaid Abdulla
+ *
+ * This file is part of GenieACS.
+ *
+ * GenieACS is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * GenieACS is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with GenieACS.  If not, see <http://www.gnu.org/licenses/>.
+ */
+"use strict";
+
+const crypto = require("crypto");
+
+const later = require("later");
+
+
+function md532(str) {
+  const digest = crypto
+    .createHash("md5")
+    .update(str)
+    .digest();
+  return (
+    digest.readUInt32LE(0) ^
+    digest.readUInt32LE(4) ^
+    digest.readUInt32LE(8) ^
+    digest.readUInt32LE(12)
+  );
+}
+
+
+function variance(deviceId, variance) {
+  return (md532(deviceId) >>> 0) % variance;
+}
+
+
+function interval(timestamp, interval, offset = 0) {
+  return Math.trunc((timestamp + offset) / interval) * interval - offset;
+}
+
+
+function parseCron(cronExp) {
+  let parts = cronExp.trim().split(/\s+/);
+  if (parts.length === 5)
+    parts.unshift("*");
+
+  return later.schedule(later.parse.cron(parts.join(" "), true));
+}
+
+
+function cron(timestamp, schedule, offset = 0) {
+  // TODO later.js doesn't throw erorr if expression is invalid!
+  const ret = [0, 0];
+
+  let prev = schedule.prev(1, new Date(timestamp + offset));
+  if (prev)
+    ret[0] = prev.setMilliseconds(0) - offset;
+
+  let next = schedule.next(1, new Date(timestamp + offset + 1000));
+  if (next)
+    ret[1] = next.setMilliseconds(0) - offset;
+
+  return ret;
+}
+
+
+exports.variance = variance;
+exports.interval = interval;
+exports.parseCron = parseCron;
+exports.cron = cron;