Changeset 17547 for gsdl/trunk/perllib/downloaders/WgetDownload.pm

Timestamp:

2008-10-15T17:45:08+13:00 (16 years ago)

Author:

ak19

Message:

When subroutines useWget and useWgetMonitored receive the STOP signal from GLI to prematurely terminate wget, these subroutines now wait 5 seconds for wget to have been launched before trying to terminate them. Previously it was possible for the kill signal to have been sent to wget before it started up, in which wget would then start running and continue in the background without anyone noticing that it hadn't gone away as it should have.

File:

• gsdl/trunk/perllib/downloaders/WgetDownload.pm (modified) (5 diffs)

gsdl/trunk/perllib/downloaders/WgetDownload.pm

@@ -100 +100 @@
     close($chld_in);
     
-    #print STDOUT "Received termination signal: $termination_signal\n";
+    print STDOUT "Received termination signal: $termination_signal\n";
 
     # Send TERM signal to child process to terminate it. Sending the INT signal doesn't work
@@ -240 +240 @@
     } 
     else { # wget finished, terminate naturally
-        #print STDERR "\nPerl: open2 command, input stream closed. Wget terminated naturally.\n";
+        #print STDOUT "\nPerl: open2 command, input stream closed. Wget terminated naturally.\n";
         close($chld_in);
         close($chld_out);
@@ -269 +269 @@
         print $client "Talked to ServerSocket (port $port). Connection accepted\n";
         
-        # Read from the client (getting rid of trailing newline)
+        # Read from the client (getting rid of the trailing newline)
         # Has the client sent the <<STOP>> signal?
         my $signal = <$client>;
@@ -275 +275 @@
         if($signal eq "<<STOP>>") {
             print $client "Perl received STOP signal (on port $port): stopping wget\n";
+            $loop = 0;
             
-            $loop = 0;
-            close($chld_in);
-            close($chld_out);
-            kill("TERM", $childpid);
-            
-            $childpid = undef;
-
-            # Stop monitoring the read_handle
-            # close the serverSocket (the Java end will close the client socket that Java opened)
-            $read_set->remove($rh); #$read_set->remove($serverSocket);
-            close($rh);         #close($serverSocket);
-            #print $client "Perl is about to exit\n";
-            last;
+            # Sometimes the wget process takes some time to start up. If the STOP signal
+            # was sent, don't try to terminate the process until we know it is running. 
+            # Otherwise wget may start running after we tried to kill it. Wait 5 seconds
+            # for it to start up, checking for whether it is running in order to kill it.
+            for(my $seconds = 1; $seconds <= 5; $seconds++) {
+            if(kill(0, $childpid)) { 
+                # If kill(0, $childpid) returns true, then the process is running
+                # and we need to kill it.
+                close($chld_in);
+                close($chld_out);
+                kill("TERM", $childpid);
+                
+                $childpid = undef;
+                
+                # Stop monitoring the read_handle and close the serverSocket 
+                # (the Java end will close the client socket that Java opened)
+                $read_set->remove($rh);     #$read_set->remove($serverSocket);
+                close($rh);             #close($serverSocket);
+                print $client "Perl terminated wget and is about to exit\n";
+            }
+            else { # the process may just be starting up, wait
+                sleep(1);
+            }
+            }
+            last; # we're done here
         }
         }
@@ -410 +423 @@
         if($signal eq "<<STOP>>") {
             print $client "Perl received STOP signal (on port $port): stopping wget\n";
+            $loop = 0;
             
-            $loop = 0;
-            close($chld_in);
-            close($chld_out);
-            kill("TERM", $childpid);
-            
-            $childpid = undef;
-
-            # Stop monitoring the read_handle
-            # close the serverSocket (the Java end will close the client socket that Java opened)
-            $read_set->remove($rh); #$read_set->remove($serverSocket);
-            close($rh);         #close($serverSocket);
-            #print $client "Perl is about to exit\n";
-            last;
+            # Sometimes the wget process takes some time to start up. If the STOP signal
+            # was sent, don't try to terminate the process until we know it is running. 
+            # Otherwise wget may start running after we tried to kill it. Wait 5 seconds
+            # for it to start up, checking for whether it is running in order to kill it.
+            for(my $seconds = 1; $seconds <= 5; $seconds++) {
+            if(kill(0, $childpid)) { 
+                # If kill(0, $childpid) returns true, then the process is running
+                # and we need to kill it.
+                close($chld_in);
+                close($chld_out);
+                kill("TERM", $childpid);
+                
+                $childpid = undef;
+                
+                # Stop monitoring the read_handle and close the serverSocket 
+                # (the Java end will close the client socket that Java opened)
+                $read_set->remove($rh);     #$read_set->remove($serverSocket);
+                close($rh);             #close($serverSocket);
+                print $client "Perl terminated wget and is about to exit\n";
+            }
+            else { # the process may just be starting up, wait
+                sleep(1);
+            }
+            }
+            last; # we're done here
         }
         }