LCOV - code coverage report
Current view: directory - image/src - DiscardTracker.cpp (source / functions) Found Hit Coverage
Test: app.info Lines: 86 54 62.8 %
Date: 2012-06-02 Functions: 10 6 60.0 %

       1                 : /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
       2                 :    ***** BEGIN LICENSE BLOCK *****
       3                 :  * Version: MPL 1.1/GPL 2.0/LGPL 2.1
       4                 :  *
       5                 :  * The contents of this file are subject to the Mozilla Public License Version
       6                 :  * 1.1 (the "License"); you may not use this file except in compliance with
       7                 :  * the License. You may obtain a copy of the License at
       8                 :  * http://www.mozilla.org/MPL/
       9                 :  *
      10                 :  * Software distributed under the License is distributed on an "AS IS" basis,
      11                 :  * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
      12                 :  * for the specific language governing rights and limitations under the
      13                 :  * License.
      14                 :  *
      15                 :  * The Original Code is mozilla.org code.
      16                 :  *
      17                 :  * The Initial Developer of the Original Code is Mozilla Foundation.
      18                 :  * Portions created by the Initial Developer are Copyright (C) 2010
      19                 :  * the Initial Developer. All Rights Reserved.
      20                 :  *
      21                 :  * Contributor(s):
      22                 :  *   Bobby Holley <bobbyholley@gmail.com>
      23                 :  *
      24                 :  * Alternatively, the contents of this file may be used under the terms of
      25                 :  * either the GNU General Public License Version 2 or later (the "GPL"), or
      26                 :  * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
      27                 :  * in which case the provisions of the GPL or the LGPL are applicable instead
      28                 :  * of those above. If you wish to allow use of your version of this file only
      29                 :  * under the terms of either the GPL or the LGPL, and not to allow others to
      30                 :  * use your version of this file under the terms of the MPL, indicate your
      31                 :  * decision by deleting the provisions above and replace them with the notice
      32                 :  * and other provisions required by the GPL or the LGPL. If you do not delete
      33                 :  * the provisions above, a recipient may use your version of this file under
      34                 :  * the terms of any one of the MPL, the GPL or the LGPL.
      35                 :  *
      36                 :  * ***** END LICENSE BLOCK ***** */
      37                 : 
      38                 : #include "nsComponentManagerUtils.h"
      39                 : #include "nsITimer.h"
      40                 : #include "RasterImage.h"
      41                 : #include "DiscardTracker.h"
      42                 : #include "mozilla/Preferences.h"
      43                 : 
      44                 : namespace mozilla {
      45                 : namespace image {
      46                 : 
      47                 : static bool sInitialized = false;
      48                 : static bool sTimerOn = false;
      49                 : static PRUint32 sMinDiscardTimeoutMs = 10000; /* Default if pref unreadable. */
      50                 : static nsITimer *sTimer = nsnull;
      51                 : static struct DiscardTrackerNode sHead, sSentinel, sTail;
      52                 : 
      53                 : /*
      54                 :  * Puts an image in the back of the tracker queue. If the image is already
      55                 :  * in the tracker, this removes it first.
      56                 :  */
      57                 : nsresult
      58               1 : DiscardTracker::Reset(DiscardTrackerNode *node)
      59                 : {
      60                 :   nsresult rv;
      61                 : #ifdef DEBUG
      62               1 :   bool isSentinel = (node == &sSentinel);
      63                 : 
      64                 :   // Sanity check the node.
      65               1 :   NS_ABORT_IF_FALSE(isSentinel || node->curr, "Node doesn't point to anything!");
      66                 : 
      67                 :   // We should not call this function if we can't discard
      68               1 :   NS_ABORT_IF_FALSE(isSentinel || node->curr->CanDiscard(),
      69                 :                     "trying to reset discarding but can't discard!");
      70                 : 
      71                 :   // As soon as an image becomes animated it is set non-discardable
      72               1 :   NS_ABORT_IF_FALSE(isSentinel || !node->curr->mAnim,
      73                 :                     "Trying to reset discarding on animated image!");
      74                 : #endif
      75                 : 
      76                 :   // Initialize the first time through
      77               1 :   if (NS_UNLIKELY(!sInitialized)) {
      78               1 :     rv = Initialize();
      79               1 :     NS_ENSURE_SUCCESS(rv, rv);
      80                 :   }
      81                 : 
      82                 :   // Remove the node if it's in the list.
      83               1 :   Remove(node);
      84                 : 
      85                 :   // Append it to the list.
      86               1 :   node->prev = sTail.prev;
      87               1 :   node->next = &sTail;
      88               1 :   node->prev->next = sTail.prev = node;
      89                 : 
      90                 :   // Make sure the timer is running
      91               1 :   rv = TimerOn();
      92               1 :   NS_ENSURE_SUCCESS(rv,rv);
      93                 : 
      94               1 :   return NS_OK;
      95                 : }
      96                 : 
      97                 : /*
      98                 :  * Removes a node from the tracker. No-op if the node is currently untracked.
      99                 :  */
     100                 : void
     101              29 : DiscardTracker::Remove(DiscardTrackerNode *node)
     102                 : {
     103              29 :   NS_ABORT_IF_FALSE(node != nsnull, "Can't pass null node");
     104                 : 
     105                 :   // If we're not in a list, we have nothing to do.
     106              29 :   if ((node->prev == nsnull) || (node->next == nsnull)) {
     107              28 :     NS_ABORT_IF_FALSE(node->prev == node->next,
     108                 :                       "Node is half in a list!");
     109              28 :     return;
     110                 :   }
     111                 : 
     112                 :   // Connect around ourselves
     113               1 :   node->prev->next = node->next;
     114               1 :   node->next->prev = node->prev;
     115                 : 
     116                 :   // Clean up the node we removed.
     117               1 :   node->prev = node->next = nsnull;
     118                 : }
     119                 : 
     120                 : /*
     121                 :  * Discard all the images we're tracking.
     122                 :  */
     123                 : void
     124               0 : DiscardTracker::DiscardAll()
     125                 : {
     126               0 :   if (!sInitialized)
     127               0 :     return;
     128                 : 
     129                 :   // Remove the sentinel from the list so that the only elements in the list
     130                 :   // which don't track an image are the head and tail.
     131               0 :   Remove(&sSentinel);
     132                 : 
     133                 :   // Discard all tracked images.
     134               0 :   for (DiscardTrackerNode *node = sHead.next;
     135                 :        node != &sTail; node = sHead.next) {
     136               0 :     NS_ABORT_IF_FALSE(node->curr, "empty node!");
     137               0 :     Remove(node);
     138               0 :     node->curr->Discard();
     139                 :   }
     140                 : 
     141                 :   // Add the sentinel back to the (now empty) list.
     142               0 :   Reset(&sSentinel);
     143                 : 
     144                 :   // Because the sentinel is the only element in the list, the next timer event
     145                 :   // would be a no-op.  Disable the timer as an optimization.
     146               0 :   TimerOff();
     147                 : }
     148                 : 
     149                 : static int
     150               0 : DiscardTimeoutChangedCallback(const char* aPref, void *aClosure)
     151                 : {
     152               0 :   DiscardTracker::ReloadTimeout();
     153               0 :   return 0;
     154                 : }
     155                 : 
     156                 : /**
     157                 :  * Initialize the tracker.
     158                 :  */
     159                 : nsresult
     160               1 : DiscardTracker::Initialize()
     161                 : {
     162                 :   nsresult rv;
     163                 : 
     164                 :   // Set up the list. Head<->Sentinel<->Tail
     165               1 :   sHead.curr = sTail.curr = sSentinel.curr = nsnull;
     166               1 :   sHead.prev = sTail.next = nsnull;
     167               1 :   sHead.next = sTail.prev = &sSentinel;
     168               1 :   sSentinel.prev = &sHead;
     169               1 :   sSentinel.next = &sTail;
     170                 : 
     171                 :   // Watch the timeout pref for changes.
     172                 :   Preferences::RegisterCallback(DiscardTimeoutChangedCallback,
     173               1 :                                 DISCARD_TIMEOUT_PREF);
     174                 : 
     175               1 :   ReloadTimeout();
     176                 : 
     177                 :   // Create and start the timer
     178               2 :   nsCOMPtr<nsITimer> t = do_CreateInstance("@mozilla.org/timer;1");
     179               1 :   NS_ENSURE_TRUE(t, NS_ERROR_OUT_OF_MEMORY);
     180               1 :   t.forget(&sTimer);
     181               1 :   rv = TimerOn();
     182               1 :   NS_ENSURE_SUCCESS(rv, rv);
     183                 : 
     184                 :   // Mark us as initialized
     185               1 :   sInitialized = true;
     186                 : 
     187               1 :   return NS_OK;
     188                 : }
     189                 : 
     190                 : /**
     191                 :  * Shut down the tracker, deallocating the timer.
     192                 :  */
     193                 : void
     194              93 : DiscardTracker::Shutdown()
     195                 : {
     196              93 :   if (sTimer) {
     197               1 :     sTimer->Cancel();
     198               1 :     NS_RELEASE(sTimer);
     199               1 :     sTimer = nsnull;
     200                 :   }
     201              93 : }
     202                 : 
     203                 : /**
     204                 :  * Read the discard timeout from about:config.
     205                 :  */
     206                 : void
     207               1 : DiscardTracker::ReloadTimeout()
     208                 : {
     209                 :   nsresult rv;
     210                 : 
     211                 :   // read the timeout pref
     212                 :   PRInt32 discardTimeout;
     213               1 :   rv = Preferences::GetInt(DISCARD_TIMEOUT_PREF, &discardTimeout);
     214                 : 
     215                 :   // If we got something bogus, return
     216               1 :   if (!NS_SUCCEEDED(rv) || discardTimeout <= 0)
     217               0 :     return;
     218                 : 
     219                 :   // If the value didn't change, return
     220               1 :   if ((PRUint32) discardTimeout == sMinDiscardTimeoutMs)
     221               1 :     return;
     222                 : 
     223                 :   // Update the value
     224               0 :   sMinDiscardTimeoutMs = (PRUint32) discardTimeout;
     225                 : 
     226                 :   // If the timer's on, restart the clock to make changes take effect
     227               0 :   if (sTimerOn) {
     228               0 :     TimerOff();
     229               0 :     TimerOn();
     230                 :   }
     231                 : }
     232                 : 
     233                 : /**
     234                 :  * Enables the timer. No-op if the timer is already running.
     235                 :  */
     236                 : nsresult
     237               2 : DiscardTracker::TimerOn()
     238                 : {
     239                 :   // Nothing to do if the timer's already on.
     240               2 :   if (sTimerOn)
     241               1 :     return NS_OK;
     242               1 :   sTimerOn = true;
     243                 : 
     244                 :   // Activate
     245                 :   return sTimer->InitWithFuncCallback(TimerCallback,
     246                 :                                       nsnull,
     247                 :                                       sMinDiscardTimeoutMs,
     248               1 :                                       nsITimer::TYPE_REPEATING_SLACK);
     249                 : }
     250                 : 
     251                 : /*
     252                 :  * Disables the timer. No-op if the timer isn't running.
     253                 :  */
     254                 : void
     255               0 : DiscardTracker::TimerOff()
     256                 : {
     257                 :   // Nothing to do if the timer's already off.
     258               0 :   if (!sTimerOn)
     259               0 :     return;
     260               0 :   sTimerOn = false;
     261                 : 
     262                 :   // Deactivate
     263               0 :   sTimer->Cancel();
     264                 : }
     265                 : 
     266                 : /**
     267                 :  * Routine activated when the timer fires. This discards everything
     268                 :  * in front of sentinel, and resets the sentinel to the back of the
     269                 :  * list.
     270                 :  */
     271                 : void
     272               0 : DiscardTracker::TimerCallback(nsITimer *aTimer, void *aClosure)
     273                 : {
     274                 :   DiscardTrackerNode *node;
     275                 : 
     276                 :   // Remove and discard everything before the sentinel
     277               0 :   for (node = sSentinel.prev; node != &sHead; node = sSentinel.prev) {
     278               0 :     NS_ABORT_IF_FALSE(node->curr, "empty node!");
     279               0 :     Remove(node);
     280               0 :     node->curr->Discard();
     281                 :   }
     282                 : 
     283                 :   // Append the sentinel to the back of the list
     284               0 :   Reset(&sSentinel);
     285                 : 
     286                 :   // If there's nothing in front of the sentinel, the next callback
     287                 :   // is guaranteed to be a no-op. Disable the timer as an optimization.
     288               0 :   if (sSentinel.prev == &sHead)
     289               0 :     TimerOff();
     290               0 : }
     291                 : 
     292                 : } // namespace image
     293                 : } // namespace mozilla

Generated by: LCOV version 1.7