Changeset 38908 for main/trunk/greenstone3/src/java/org/greenstone/applet/GsdlCollageApplet/DownloadUrls.java

Timestamp:

2024-04-06T22:41:44+13:00 (2 months ago)

Author:

anupama

Message:

Tried to replace calls to deprecated and dangerous applet stop(). But one problem remains constant between using stop() and the new, custom stopRunning() when GsdlCollageApplet is run in webswing: Unless the application is manually exited (when run as an application in webswing, the exit button is available), I don't see stop() or stopRunning() called in the log at packages/tomcat/bin/logs/webswing.log. Yet is webswing always relaunching the app and calling its init() method, which would start creating new threads and downloading and other things? What happens to the objects never terminated and garbage collected unless explicitly exited? How do I in Java detect that the webswing browser window has been redirected to another page? TODO: Maybe this can be resolved with a Java-JavaScript communication between webswing and the app. TODO2: MyAffineTransform line 39, why is there a division by zero error at times when the app window dimensions ought to always be positive now? TODO3: I want the status bar gone. It is not being used anyway and at present, sometimes the outlines of its dimensions appear, even though they shouldn't. This occasional behaviour (whether the MyAffineTransform error or status bar) is another bother for debugging.

File:

• main/trunk/greenstone3/src/java/org/greenstone/applet/GsdlCollageApplet/DownloadUrls.java (modified) (16 diffs)

main/trunk/greenstone3/src/java/org/greenstone/applet/GsdlCollageApplet/DownloadUrls.java

@@ -8 +8 @@
 import javax.swing.ImageIcon; //****
 
+//import org.apache.log4j.*;
 
 /** 
@@ -21 +22 @@
 
 public class DownloadUrls extends Thread {
+    
     // for GS3    
     String baseURL = null;
@@ -35 +37 @@
     String document_root_ = null;
 
-
+    /** When this thread is asked to stop running, this variable will be set to true */
+    private boolean stop_running = false;    
+
+    /** When this thread is asked to stop downloading, this variable will be set to true.
+     * For now the behaviour is the same as stop_running=true on this thread,
+     * but in case it changes in the future, we have a separate variable.
+     * Also, calling stopRunning() is not the same as setting stop_running = true, so 
+     * to be careful, a separate variable for stop_downloading could be safer when coding.
+     */
+    private boolean stop_downloading = false;
+    
     /** CHRIS - Holds the contents of the collection's assoc directory */
     //    File[] assocDir_ = null;
@@ -181 +193 @@
     }
 
-   
-
+    // some other thread can call this method to tell this thread to stop running
+    public void stopRunning() {
+    if (verbosity_ >= 3) {
+        System.err.println("**** DownloadUrls.stopRunning() called");
+    }
+    
+    stop_running = true;
+    // Interrupt this thread, even if it's not the one running
+    // Just want to make sure the DownloadURls' thread the CURL object runs in
+    // gets interrupted if it's what's currently running
+    if(!this.isInterrupted()) {
+        this.interrupt();
+    }
+    if(!Thread.currentThread().isInterrupted()) {
+        Thread.currentThread().interrupt();
+    }
+    }
+
+    public boolean isStopping() {
+    return stop_running;
+    }
 
 
@@ -390 +421 @@
        try{
            // if have completed the maximum number of downloads for the
-           // application then stop
+           // application then stop downloading
            if (size == app_.maxDownloads()) {
-           stop();
+           // NOTE: the app can continue displaying images forever after download is
+           // finished, until interrupted/stopped.
+           // So don't set stop_running=false just because downloads have finished.
+           //stop_running = true; // Don't do this!
+           //thread_running = false;
+           //thread.currentThread().interrupt();
+
+           stop_downloading = true;
+           //stop(); // TODO, remove this, replacing with above
+           
            }
            
@@ -398 +438 @@
        catch (Exception e) {
            thread_running_ = false;
-           stop();
+           //stop(); // TODO
+           stop_downloading = true;
            e.printStackTrace();
        }
@@ -412 +453 @@
     public void rec_add_images(String new_url, int depth)
     {
-
     if (verbosity_ >= 2) {
         System.err.println("*** Inspecting url: " + new_url);
@@ -424 +464 @@
 
     // connect to the url
+    // stopRunning would have set the interrupted flag, and
+    // CURL checks for that in its loop, *outside* its potentially-blocking read() call
     CURL curl = (app_.gsdlversion == 3) ? new CURL(new_url, app_.baseURL) : new CURL(new_url);
 
@@ -445 +487 @@
         }
         // process each of the image links according to the parameters given.
-        for (int i = 0; i < src_links.size(); i++) 
+        for (int i = 0; i < src_links.size() && !stop_running && !stop_downloading; i++) 
         {
         URL url = (URL)src_links.get(i);
@@ -491 +533 @@
         }
 
+        if(stop_running && verbosity_ >= 3) {
+        System.err.println("*** DownloadUrls.rec_add_images() - Asked to stop running");
+        return;
+        }
+        
         // get all the <code><a href=</code> links into a vector
         Vector href_links = curl.getHrefLinks();
@@ -500 +547 @@
 
         // process each of the href links according to the parameters given.
-        for (int i = 0; i < href_links.size(); i++) 
+        for (int i = 0; i < href_links.size() && !stop_running && !stop_downloading; i++) 
         {
            
@@ -546 +593 @@
         System.err.println("Unable able to download "+new_url);
     }
+
+    if(stop_running && verbosity_ >= 3) {
+        System.err.println("*** DownloadUrls.rec_add_images() thread has been told to stop.");
+    }
     }
 
@@ -566 +617 @@
         return;
         }
-        
+
         // open a url to the file written
         URL u = new URL(starting_url_ + "externallinks");
@@ -576 +627 @@
         String l = r.readLine();
         // split the line of the space, first part is the image, second part the link
-        while (l != null) {
+        while (l != null && !stop_running && !stop_downloading) {
     
         String tmp1 = new String();
@@ -600 +651 @@
         r.close();
 
+        if(stop_running && verbosity_ >= 3) {
+            System.err.println("*** DownloadUrls.externalLinks(): Asked to stop running");
+        }
+        
     } catch (Exception e) {
         e.printStackTrace();
@@ -612 +667 @@
     visited_url_ = new Hashtable();
     visited_images_ = new Hashtable();
-
-        rec_add_images(starting_url_,1);
+    
+    rec_add_images(starting_url_,1);
     download_images_.stopDownload();
-    System.err.println("Download thread finished.");
+    System.err.println("DownloadUrls.run() - download thread finished.");
     }
 }