Changeset 665

Timestamp:

Mar 10, 2010, 1:33:14 AM (15 years ago)

Author:

Dmitry A. Kuminov

Message:

corelib: Sockets: Fixed: "has data to read" socket notifications would be sometimes delivered with a delay depending on the frequency of timers which could significantly slow down network data transfer.

File:

• trunk/src/corelib/kernel/qeventdispatcher_pm.cpp (modified) (8 diffs)

trunk/src/corelib/kernel/qeventdispatcher_pm.cpp

@@ -322 +322 @@
     int refcnt;
     QWaitCondition cond;
-    bool cancelWait;
 
     // socket stuff
@@ -331 +330 @@
 
     fd_set readS, writeS, exS;
-    int maxSockfd;
+    int maxSockfd;
 
     // timer stuff
@@ -699 +698 @@
 
 QSelectThread::QSelectThread()
-    : finish(false), refcnt(0), cancelWait(false), allTimersPosted(false)
+    : finish(false), refcnt(0), allTimersPosted(false)
 {
     // initialize socket stuff
@@ -705 +704 @@
     FD_ZERO(&writeS);
     FD_ZERO(&exS);
-    maxSockfd = -1;
+    maxSockfd = -1;
 
     // initialize timer stuff
@@ -786 +785 @@
         if (maxSockfd >= 0) {
             fd_set tmpRead = readS, tmpWrite = writeS, tmpEx = exS;
+
             mutex.unlock();
-            nsel = ::select(maxSockfd + 1, &tmpRead, &tmpWrite, &tmpEx, timeout);
+            nsel = ::select(maxSockfd
             if (nsel == -1 && errno == EINVAL) {
                 qWarning("QSocketNotifier: select() returned EINVAL, check that "
                          "the socket is not an OS/2 file handle.");
-                // give it some sleep to let other threads do something
-                DosSleep(100);
+                // give it some sleep to avoid 100% CPU load due to select()
+                // constantly failing in a tight loop which freezes the system
+                msleep(100);
             }
             mutex.lock();
@@ -814 +815 @@
                     }
                     if (isSet) {
+
+
+
                         FD_CLR(sockfd, setForType(type));
                         updateMaxSockFd(sockfd, Remove);
@@ -822 +826 @@
         } else {
             nsel = -1;
-            errno = EINTR;
-            if (!cancelWait) {
-                long msecs = timeout ?
-                    timeout->tv_sec * 1000l + timeout->tv_usec / 1000l : LONG_MAX;
-                if (!cond.wait(&mutex, msecs))
-                    nsel = 0; // indicate timeout
-            }
-            cancelWait = false;
+            errno = EINTR; // indicate interrupt
+            long msecs = timeout ?
+                timeout->tv_sec * 1000l + timeout->tv_usec / 1000l : LONG_MAX;
+            maxSockfdInSelect = -1;
+            if (!cond.wait(&mutex, msecs))
+                nsel = 0; // indicate timeout
         }
 
@@ -846 +848 @@
 void QSelectThread::cancelSelectOrIdle()
 {
-    if (maxSockfd >= 0) {
+    if (maxSockfdInSelect < 0) {
+        // terminate the idle or simple wait state
+        cond.wakeOne();
+    } else {
         // terminate select() execution
-        ::so_cancel(maxSockfd);
-    } else {
-        // terminate the idle or simple wait state
-        if (!cancelWait) {
-            cancelWait = true;
-            cond.wakeOne();
-        }
+        ::so_cancel(maxSockfdInSelect);
     }
 }