Implemented a timer for loading CSS style sheets to allow content to be displayed if the sheet is taking too long to load. b=17309 r=nisheeth

content/html/document/src/nsHTMLContentSink.cpp

@@ -102,6 +102,7 @@
 #include "nsDOMError.h"
 #include "nsIScrollable.h"
 
+// #define ALLOW_ASYNCH_STYLE_SHEETS
 #ifdef ALLOW_ASYNCH_STYLE_SHEETS
 const PRBool kBlock=PR_FALSE;
 #else
@@ -345,6 +346,11 @@ public:
   PRInt32             mInsideNoXXXTag;
   PRInt32             mInMonolithicContainer;
 
+  nsCOMPtr<nsITimer>  mStyleSheetTimer;           // timer used to prevent infinite wait for style sheet
+  PRBool              mStyleSheetTimerSet;        // TRUE if a timer has been set since Init
+  PRInt32             mStyleSheetTimerInterval;   // interval in milliseconds
+  PRUint32            mNumStyleSheetsLoading;     // number of style sheets still loading
+
   void StartLayout();
 
   void ScrollToRef();
@@ -2084,6 +2090,8 @@ HTMLContentSink::HTMLContentSink() {
   mInNotification = 0;
   mInMonolithicContainer = 0;
   mInsideNoXXXTag  = 0;
+
+  mStyleSheetTimerSet = PR_FALSE;
 }
 
 HTMLContentSink::~HTMLContentSink()
@@ -2112,6 +2120,10 @@ HTMLContentSink::~HTMLContentSink()
     mNotificationTimer->Cancel();
   }
 
+  if (mStyleSheetTimer) {
+    mStyleSheetTimer->Cancel();
+  }
+
   PRInt32 numContexts = mContextStack.Count();
   
   if(mCurrentContext==mHeadContext) {
@@ -2205,6 +2217,11 @@ HTMLContentSink::Init(nsIDocument* aDoc,
   mMaxTextRun = 8192;
   prefs->GetIntPref("content.maxtextrun", &mMaxTextRun);
 
+  mStyleSheetTimerSet = PR_FALSE;
+  mNumStyleSheetsLoading = 0;
+  mStyleSheetTimerInterval = (5*1000);
+  prefs->GetIntPref("content.notify.stylesheettimeout", &mStyleSheetTimerInterval);
+
   nsIHTMLContentContainer* htmlContainer = nsnull;
   if (NS_SUCCEEDED(aDoc->QueryInterface(kIHTMLContentContainerIID, (void**)&htmlContainer))) {
     htmlContainer->GetCSSLoader(mCSSLoader);
@@ -2284,6 +2301,11 @@ HTMLContentSink::DidBuildModel(PRInt32 aQualityLevel)
     mNotificationTimer = 0;
   }
 
+  if (mStyleSheetTimer) {
+    mStyleSheetTimer->Cancel();
+    mStyleSheetTimer = 0;
+  } 
+  
   if (nsnull == mTitle) {
     mHTMLDocument->SetTitle("");
   }
@@ -2320,8 +2342,15 @@ HTMLContentSink::DidBuildModel(PRInt32 aQualityLevel)
 NS_IMETHODIMP_(void)
 HTMLContentSink::Notify(nsITimer *timer)
 {
+  if (timer == mStyleSheetTimer.get()) {
+    // our first sheet timer has expired: resume the parser now
+    mStyleSheetTimer = 0;
+    ResumeParsing();
+  } else {
+
     MOZ_TIMER_DEBUGLOG(("Start: nsHTMLContentSink::Notify()\n"));
     MOZ_TIMER_START(mWatch);
+  
   #ifdef MOZ_DEBUG
     PRTime now = PR_Now();
     PRInt64 diff, interval;
@@ -2338,13 +2367,16 @@ HTMLContentSink::Notify(nsITimer *timer)
     SINK_TRACE(SINK_TRACE_REFLOW,
                ("HTMLContentSink::Notify: reflow on a timer: %d milliseconds late, backoff count: %d", delay, mBackoffCount));
   #endif
+
     if (mCurrentContext) {
       mCurrentContext->FlushTags(PR_TRUE);
     }
     mNotificationTimer = 0;
+
     MOZ_TIMER_DEBUGLOG(("Stop: nsHTMLContentSink::Notify()\n"));
     MOZ_TIMER_STOP(mWatch);
   }
+}
 
 NS_IMETHODIMP
 HTMLContentSink::WillInterrupt()
@@ -2420,6 +2452,7 @@ HTMLContentSink::WillResume()
 {
   SINK_TRACE(SINK_TRACE_CALLS,
              ("HTMLContentSink::WillResume: this=%p", this));
+
   // Cancel a timer if we had one out there
   if (mNotificationTimer) {
     SINK_TRACE(SINK_TRACE_REFLOW,
@@ -2427,7 +2460,6 @@ HTMLContentSink::WillResume()
     mNotificationTimer->Cancel();
     mNotificationTimer = 0;
   }
-
   return NS_OK;
 }
 
@@ -3659,6 +3691,14 @@ NS_IMETHODIMP
 HTMLContentSink::StyleSheetLoaded(nsICSSStyleSheet* aSheet, 
                                   PRBool aDidNotify)
 {
+  mNumStyleSheetsLoading--;
+
+  // if out timer is still pending, cancel it.
+  if (mNumStyleSheetsLoading==0 && mStyleSheetTimer) {
+    mStyleSheetTimer->Cancel();
+    mStyleSheetTimer = 0;
+  }
+
   // If there was a notification done for this style sheet, we know
   // that frames have been created for all content seen so far
   // (processing of a new style sheet causes recreation of the frame
@@ -3719,6 +3759,9 @@ HTMLContentSink::ProcessStyleLink(nsIHTMLContent* aElement,
 		}
 		
     if (isStyleSheet) {
+      PRBool blockParser = kBlock;
+      PRBool important = PR_FALSE;
+      PRBool alternate = PR_FALSE;  // alternate (non-preferred) style sheet
       nsIURI* url = nsnull;
       {
         result = NS_NewURI(&url, aHref, mDocumentBaseURL);
@@ -3733,14 +3776,19 @@ HTMLContentSink::ProcessStyleLink(nsIHTMLContent* aElement,
             mPreferredStyle = aTitle;
             mCSSLoader->SetPreferredSheet(aTitle);
             mDocument->SetHeaderData(nsHTMLAtoms::headerDefaultStyle, aTitle);
+          } else {
+            alternate = PR_TRUE;
           }
         }
       }
 
-      PRBool blockParser = kBlock;
-
       if (-1 != linkTypes.IndexOf("important")) {
         blockParser = PR_TRUE;
+        important = PR_TRUE;
+      }
+
+      if (alternate && !important) {
+        blockParser = PR_FALSE;
       }
 
       PRBool doneLoading;
@@ -3750,10 +3798,36 @@ HTMLContentSink::ProcessStyleLink(nsIHTMLContent* aElement,
                                          doneLoading, 
                                          this);
       NS_RELEASE(url);
-      if (NS_SUCCEEDED(result) && blockParser && (! doneLoading)) {
+      if (NS_SUCCEEDED(result) && (!doneLoading)) {
+        // we are loading another one, so increment the counter
+        mNumStyleSheetsLoading++;
+        // if important, then just block
+        if (important) {
+          NS_ASSERTION(blockParser, "Must block for important styleSheets");
+          result = NS_ERROR_HTMLPARSER_BLOCK;
+        } else {
+          // if not blocking the parser absolutely (!important) 
+          // then setup a notification timer so we can locally 
+          // unblock the parser if it takes too long
+          // bug=17309
+          if (blockParser) {
+            NS_ASSERTION(!alternate, "Alternates should not block parser");
+            // if no stylesheet timer, and none was previously set (ie. first one), then start one
+            if (!mStyleSheetTimer && !mStyleSheetTimerSet) {
+              result = NS_NewTimer(getter_AddRefs(mStyleSheetTimer));
+              if (NS_SUCCEEDED(result)) {
+                result = mStyleSheetTimer->Init(this, mStyleSheetTimerInterval);
+                if( NS_SUCCEEDED(result)) {
+                  mStyleSheetTimerSet = PR_TRUE;
+                  // block the parser: we will unblock it when the timer expires
                   result = NS_ERROR_HTMLPARSER_BLOCK;
                 }
               }
+            }// if no stylesheet timer
+          }// if !important and blockParser
+        } // if important
+      } // if succeeded && !doneLoading
+    }
   }
   return result;
 }

layout/html/document/src/nsHTMLContentSink.cpp

@@ -102,6 +102,7 @@
 #include "nsDOMError.h"
 #include "nsIScrollable.h"
 
+// #define ALLOW_ASYNCH_STYLE_SHEETS
 #ifdef ALLOW_ASYNCH_STYLE_SHEETS
 const PRBool kBlock=PR_FALSE;
 #else
@@ -345,6 +346,11 @@ public:
   PRInt32             mInsideNoXXXTag;
   PRInt32             mInMonolithicContainer;
 
+  nsCOMPtr<nsITimer>  mStyleSheetTimer;           // timer used to prevent infinite wait for style sheet
+  PRBool              mStyleSheetTimerSet;        // TRUE if a timer has been set since Init
+  PRInt32             mStyleSheetTimerInterval;   // interval in milliseconds
+  PRUint32            mNumStyleSheetsLoading;     // number of style sheets still loading
+
   void StartLayout();
 
   void ScrollToRef();
@@ -2084,6 +2090,8 @@ HTMLContentSink::HTMLContentSink() {
   mInNotification = 0;
   mInMonolithicContainer = 0;
   mInsideNoXXXTag  = 0;
+
+  mStyleSheetTimerSet = PR_FALSE;
 }
 
 HTMLContentSink::~HTMLContentSink()
@@ -2112,6 +2120,10 @@ HTMLContentSink::~HTMLContentSink()
     mNotificationTimer->Cancel();
   }
 
+  if (mStyleSheetTimer) {
+    mStyleSheetTimer->Cancel();
+  }
+
   PRInt32 numContexts = mContextStack.Count();
   
   if(mCurrentContext==mHeadContext) {
@@ -2205,6 +2217,11 @@ HTMLContentSink::Init(nsIDocument* aDoc,
   mMaxTextRun = 8192;
   prefs->GetIntPref("content.maxtextrun", &mMaxTextRun);
 
+  mStyleSheetTimerSet = PR_FALSE;
+  mNumStyleSheetsLoading = 0;
+  mStyleSheetTimerInterval = (5*1000);
+  prefs->GetIntPref("content.notify.stylesheettimeout", &mStyleSheetTimerInterval);
+
   nsIHTMLContentContainer* htmlContainer = nsnull;
   if (NS_SUCCEEDED(aDoc->QueryInterface(kIHTMLContentContainerIID, (void**)&htmlContainer))) {
     htmlContainer->GetCSSLoader(mCSSLoader);
@@ -2284,6 +2301,11 @@ HTMLContentSink::DidBuildModel(PRInt32 aQualityLevel)
     mNotificationTimer = 0;
   }
 
+  if (mStyleSheetTimer) {
+    mStyleSheetTimer->Cancel();
+    mStyleSheetTimer = 0;
+  } 
+  
   if (nsnull == mTitle) {
     mHTMLDocument->SetTitle("");
   }
@@ -2320,8 +2342,15 @@ HTMLContentSink::DidBuildModel(PRInt32 aQualityLevel)
 NS_IMETHODIMP_(void)
 HTMLContentSink::Notify(nsITimer *timer)
 {
+  if (timer == mStyleSheetTimer.get()) {
+    // our first sheet timer has expired: resume the parser now
+    mStyleSheetTimer = 0;
+    ResumeParsing();
+  } else {
+
     MOZ_TIMER_DEBUGLOG(("Start: nsHTMLContentSink::Notify()\n"));
     MOZ_TIMER_START(mWatch);
+  
   #ifdef MOZ_DEBUG
     PRTime now = PR_Now();
     PRInt64 diff, interval;
@@ -2338,13 +2367,16 @@ HTMLContentSink::Notify(nsITimer *timer)
     SINK_TRACE(SINK_TRACE_REFLOW,
                ("HTMLContentSink::Notify: reflow on a timer: %d milliseconds late, backoff count: %d", delay, mBackoffCount));
   #endif
+
     if (mCurrentContext) {
       mCurrentContext->FlushTags(PR_TRUE);
     }
     mNotificationTimer = 0;
+
     MOZ_TIMER_DEBUGLOG(("Stop: nsHTMLContentSink::Notify()\n"));
     MOZ_TIMER_STOP(mWatch);
   }
+}
 
 NS_IMETHODIMP
 HTMLContentSink::WillInterrupt()
@@ -2420,6 +2452,7 @@ HTMLContentSink::WillResume()
 {
   SINK_TRACE(SINK_TRACE_CALLS,
              ("HTMLContentSink::WillResume: this=%p", this));
+
   // Cancel a timer if we had one out there
   if (mNotificationTimer) {
     SINK_TRACE(SINK_TRACE_REFLOW,
@@ -2427,7 +2460,6 @@ HTMLContentSink::WillResume()
     mNotificationTimer->Cancel();
     mNotificationTimer = 0;
   }
-
   return NS_OK;
 }
 
@@ -3659,6 +3691,14 @@ NS_IMETHODIMP
 HTMLContentSink::StyleSheetLoaded(nsICSSStyleSheet* aSheet, 
                                   PRBool aDidNotify)
 {
+  mNumStyleSheetsLoading--;
+
+  // if out timer is still pending, cancel it.
+  if (mNumStyleSheetsLoading==0 && mStyleSheetTimer) {
+    mStyleSheetTimer->Cancel();
+    mStyleSheetTimer = 0;
+  }
+
   // If there was a notification done for this style sheet, we know
   // that frames have been created for all content seen so far
   // (processing of a new style sheet causes recreation of the frame
@@ -3719,6 +3759,9 @@ HTMLContentSink::ProcessStyleLink(nsIHTMLContent* aElement,
 		}
 		
     if (isStyleSheet) {
+      PRBool blockParser = kBlock;
+      PRBool important = PR_FALSE;
+      PRBool alternate = PR_FALSE;  // alternate (non-preferred) style sheet
       nsIURI* url = nsnull;
       {
         result = NS_NewURI(&url, aHref, mDocumentBaseURL);
@@ -3733,14 +3776,19 @@ HTMLContentSink::ProcessStyleLink(nsIHTMLContent* aElement,
             mPreferredStyle = aTitle;
             mCSSLoader->SetPreferredSheet(aTitle);
             mDocument->SetHeaderData(nsHTMLAtoms::headerDefaultStyle, aTitle);
+          } else {
+            alternate = PR_TRUE;
           }
         }
       }
 
-      PRBool blockParser = kBlock;
-
       if (-1 != linkTypes.IndexOf("important")) {
         blockParser = PR_TRUE;
+        important = PR_TRUE;
+      }
+
+      if (alternate && !important) {
+        blockParser = PR_FALSE;
       }
 
       PRBool doneLoading;
@@ -3750,10 +3798,36 @@ HTMLContentSink::ProcessStyleLink(nsIHTMLContent* aElement,
                                          doneLoading, 
                                          this);
       NS_RELEASE(url);
-      if (NS_SUCCEEDED(result) && blockParser && (! doneLoading)) {
+      if (NS_SUCCEEDED(result) && (!doneLoading)) {
+        // we are loading another one, so increment the counter
+        mNumStyleSheetsLoading++;
+        // if important, then just block
+        if (important) {
+          NS_ASSERTION(blockParser, "Must block for important styleSheets");
+          result = NS_ERROR_HTMLPARSER_BLOCK;
+        } else {
+          // if not blocking the parser absolutely (!important) 
+          // then setup a notification timer so we can locally 
+          // unblock the parser if it takes too long
+          // bug=17309
+          if (blockParser) {
+            NS_ASSERTION(!alternate, "Alternates should not block parser");
+            // if no stylesheet timer, and none was previously set (ie. first one), then start one
+            if (!mStyleSheetTimer && !mStyleSheetTimerSet) {
+              result = NS_NewTimer(getter_AddRefs(mStyleSheetTimer));
+              if (NS_SUCCEEDED(result)) {
+                result = mStyleSheetTimer->Init(this, mStyleSheetTimerInterval);
+                if( NS_SUCCEEDED(result)) {
+                  mStyleSheetTimerSet = PR_TRUE;
+                  // block the parser: we will unblock it when the timer expires
                   result = NS_ERROR_HTMLPARSER_BLOCK;
                 }
               }
+            }// if no stylesheet timer
+          }// if !important and blockParser
+        } // if important
+      } // if succeeded && !doneLoading
+    }
   }
   return result;
 }