From 09994438e58bef3c04dfb851f54fb547d9c22f02 Mon Sep 17 00:00:00 2001
From: Ryan Dahl <ry@tinyclouds.org>
Date: Thu, 13 Jan 2011 02:09:03 -0800
Subject: [PATCH] Expose link-list from timers.js; add tests

---
 lib/timers.js                          | 115 +++++++++++++++----------
 test/simple/test-timers-linked-list.js |  94 ++++++++++++++++++++
 2 files changed, 165 insertions(+), 44 deletions(-)
 create mode 100644 test/simple/test-timers-linked-list.js

diff --git a/lib/timers.js b/lib/timers.js
index c1b8a0291fd..d0ec0c8d9da 100644
--- a/lib/timers.js
+++ b/lib/timers.js
@@ -9,6 +9,69 @@ if (process.env.NODE_debug && /timer/.test(process.env.NODE_debug)) {
 }
 
 
+// Export the linklist code for testing.
+
+
+exports.linkedList = {};
+
+
+function init(list) {
+  list._idleNext = list;
+  list._idlePrev = list;
+}
+exports.linkedList.init = init;
+
+
+// show the most idle item
+function peek(list) {
+  if (list._idlePrev == list) return null;
+  return list._idlePrev;
+}
+exports.linkedList.peek = peek;
+
+
+// remove the most idle item from the list
+function shift(list) {
+  var first = list._idlePrev;
+  remove(first);
+  return first;
+}
+exports.linkedList.shift = shift;
+
+
+// remove a item from its list
+function remove(item) {
+  if (item._idleNext) {
+    item._idleNext._idlePrev = item._idlePrev;
+  }
+
+  if (item._idlePrev) {
+    item._idlePrev._idleNext = item._idleNext;
+  }
+
+  item._idleNext = null;
+  item._idlePrev = null;
+}
+exports.linkedList.remove = remove;
+
+
+// remove a item from its list and place at the end.
+function append(list, item) {
+  remove(item);
+  item._idleNext = list._idleNext;
+  list._idleNext._idlePrev = item;
+  item._idlePrev = list;
+  list._idleNext = item;
+}
+exports.linkedList.append = append;
+
+
+function isEmpty(list) {
+  return list._idleNext === list;
+}
+exports.linkedList.isEmpty = isEmpty;
+
+
 // IDLE TIMEOUTS
 //
 // Because often many sockets will have the same idle timeout we will not
@@ -22,36 +85,6 @@ if (process.env.NODE_debug && /timer/.test(process.env.NODE_debug)) {
 // value = list
 var lists = {};
 
-// show the most idle item
-function peek(list) {
-  if (list._idlePrev == list) return null;
-  return list._idlePrev;
-}
-
-
-// remove the most idle item from the list
-function shift(list) {
-  var first = list._idlePrev;
-  remove(first);
-  return first;
-}
-
-
-// remove a item from its list
-function remove(item) {
-  item._idleNext._idlePrev = item._idlePrev;
-  item._idlePrev._idleNext = item._idleNext;
-}
-
-
-// remove a item from its list and place at the end.
-function append(list, item) {
-  item._idleNext = list._idleNext;
-  list._idleNext._idlePrev = item;
-  item._idlePrev = list;
-  list._idleNext = item;
-}
-
 
 // the main function - creates lists on demand and the watchers associated
 // with them.
@@ -67,8 +100,7 @@ function insert(item, msecs) {
     list = lists[msecs];
   } else {
     list = new Timer();
-    list._idleNext = list;
-    list._idlePrev = list;
+    init(list);
 
     lists[msecs] = list;
 
@@ -78,6 +110,7 @@ function insert(item, msecs) {
       // just set its repeat
       var now = new Date();
       debug('now: ' + now);
+
       var first;
       while (first = peek(list)) {
         var diff = now - first._idleStart;
@@ -91,8 +124,9 @@ function insert(item, msecs) {
           if (first._onTimeout) first._onTimeout();
         }
       }
+
       debug(msecs + ' list empty');
-      assert(list._idleNext === list); // list is empty
+      assert(isEmpty(list));
       list.stop();
     };
   }
@@ -103,7 +137,7 @@ function insert(item, msecs) {
   }
 
   append(list, item);
-  assert(list._idleNext !== list); // list is not empty
+  assert(!isEmpty(list)); // list is not empty
 }
 
 
@@ -114,7 +148,7 @@ var unenroll = exports.unenroll = function(item) {
     var list = lists[item._idleTimeout];
     // if empty then stop the watcher
     debug('unenroll');
-    if (list && list._idlePrev == list) {
+    if (list && isEmpty(list)) {
       debug('unenroll: list empty');
       list.stop();
     }
@@ -129,8 +163,7 @@ exports.enroll = function(item, msecs) {
   if (item._idleNext) unenroll(item);
 
   item._idleTimeout = msecs;
-  item._idleNext = item;
-  item._idlePrev = item;
+  init(item);
 };
 
 // call this whenever the item is active (not idle)
@@ -142,14 +175,8 @@ exports.active = function(item) {
     if (item._idleNext == item) {
       insert(item, msecs);
     } else {
-      // inline append
       item._idleStart = new Date();
-      item._idleNext._idlePrev = item._idlePrev;
-      item._idlePrev._idleNext = item._idleNext;
-      item._idleNext = list._idleNext;
-      item._idleNext._idlePrev = item;
-      item._idlePrev = list;
-      list._idleNext = item;
+      append(list, item);
     }
   }
 };
diff --git a/test/simple/test-timers-linked-list.js b/test/simple/test-timers-linked-list.js
new file mode 100644
index 00000000000..9caa909d010
--- /dev/null
+++ b/test/simple/test-timers-linked-list.js
@@ -0,0 +1,94 @@
+var common = require('../common');
+var assert = require('assert');
+var L = require('timers').linkedList;
+
+
+var list = { name: "list" };
+var A = { name: "A" };
+var B = { name: "B" };
+var C = { name: "C" };
+var D = { name: "D" };
+
+
+L.init(list);
+assert.ok(L.isEmpty(list));
+assert.equal(null, L.peek(list));
+
+L.append(list, A);
+// list -> A
+assert.equal(A, L.peek(list));
+
+L.append(list, B);
+// list -> A -> B
+assert.equal(A, L.peek(list));
+
+L.append(list, C);
+// list -> A -> B -> C
+assert.equal(A, L.peek(list));
+
+L.append(list, D);
+// list -> A -> B -> C -> D
+assert.equal(A, L.peek(list));
+
+var x = L.shift(list);
+assert.equal(A, x);
+// list -> B -> C -> D
+assert.equal(B, L.peek(list));
+
+x = L.shift(list);
+assert.equal(B, x);
+// list -> C -> D
+assert.equal(C, L.peek(list));
+
+// B is already removed, so removing it again shouldn't hurt.
+L.remove(B);
+// list -> C -> D
+assert.equal(C, L.peek(list));
+
+// Put B back on the list
+L.append(list, B);
+// list -> C -> D -> B
+assert.equal(C, L.peek(list));
+
+L.remove(C);
+// list -> D -> B
+assert.equal(D, L.peek(list));
+
+L.remove(B);
+// list -> D
+assert.equal(D, L.peek(list));
+
+L.remove(D);
+// list 
+assert.equal(null, L.peek(list));
+
+
+assert.ok(L.isEmpty(list));
+
+
+L.append(list, D);
+// list -> D
+assert.equal(D, L.peek(list));
+
+L.append(list, C);
+L.append(list, B);
+L.append(list, A);
+// list -> D -> C -> B -> A
+
+// Append should REMOVE C from the list and append it to the end.
+L.append(list, C);
+
+// list -> D -> B -> A -> C
+assert.equal(D, L.shift(list));
+// list -> B -> A -> C
+assert.equal(B, L.peek(list));
+assert.equal(B, L.shift(list));
+// list -> A -> C
+assert.equal(A, L.peek(list));
+assert.equal(A, L.shift(list));
+// list -> C
+assert.equal(C, L.peek(list));
+assert.equal(C, L.shift(list));
+// list
+assert.ok(L.isEmpty(list));
+