The great big resource manager revamp: the resource manager now supports

the JNLP versioned resource protocol so that it can download jardiffs
instead of whole new jar files when a resource bundle is updated.
Unversioned http downloads (which we'll probably continue to use for the
dynamically generated island bundles) are currently not working.


git-svn-id: svn+ssh://src.earth.threerings.net/narya/trunk@2739 542714f4-19e9-0310-aa3c-eee0fc999fb1

src/java/com/threerings/resource/Downloader.java

@@ -0,0 +1,153 @@
+//
+// $Id: Downloader.java,v 1.1 2003/08/05 01:33:20 mdb Exp $
+
+package com.threerings.resource;
+
+import java.io.File;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.net.URLConnection;
+
+import com.threerings.resource.DownloadManager.DownloadDescriptor;
+import com.threerings.resource.DownloadManager.DownloadObserver;
+
+/**
+ * Does something extraordinary.
+ */
+public abstract class Downloader
+{
+    /**
+     * Provides this downloader with a reference to the download
+     * descriptor it needs to do its business.
+     */
+    public void init (DownloadDescriptor ddesc)
+    {
+        _desc = ddesc;
+        _desc.destFileSize = _desc.destFile.length();
+        _desc.destLastModified = _desc.destFile.lastModified();
+    }
+
+    /**
+     * Returns a reference to the descriptor we are downloading.
+     */
+    public DownloadDescriptor getDescriptor ()
+    {
+        return _desc;
+    }
+
+    /**
+     * Requests that this downloader determine whether it needs to be
+     * updated and if so, it should add its total download requirement to
+     * {@link ProgressInfo#totalSize} the supplied {@link ProgressInfo}
+     * record.
+     *
+     * @return true if this downloader needs be updated, false if not.
+     */
+    public abstract boolean checkUpdate (ProgressInfo info)
+        throws IOException;
+
+    /**
+     * Compares the supplied size and last modified time with the size and
+     * last modified time of our local copy of the file.
+     */
+    protected boolean compareWithLocal (long fileSize, long lastModified)
+    {
+        // check to see whether we have a local copy at all, and if so,
+        // whether its file size or last-modified time differs from the
+        // source file modulo a delta to account for inexactness on the
+        // part of the file-system (thanks Microsoft)
+        return ((!_desc.destFile.exists()) ||
+                (_desc.destFileSize != fileSize) ||
+                (_desc.destLastModified < (lastModified - DELTA)) ||
+                (_desc.destLastModified > (lastModified + DELTA)));
+    }
+
+    /**
+     * Processes a single download descriptor.
+     */
+    public void processDownload (DownloadManager dmgr, DownloadObserver obs,
+                                 ProgressInfo pinfo, byte[] buffer)
+        throws IOException
+    {
+        // download the resource bundle from the specified URL
+        URLConnection ucon = _desc.sourceURL.openConnection();
+
+        // prepare to read the data from the URL into the cache file
+        Log.info("Downloading file [url=" + _desc.sourceURL + "].");
+        downloadContent(dmgr, obs, pinfo, buffer, ucon, _desc.destFile);
+
+        // if we have a last modified time, we want to adjust our cache
+        // file accordingly
+        if (_desc.lastModified != 0) {
+            if (!_desc.destFile.setLastModified(_desc.lastModified)) {
+                Log.warning("Failed to set last-modified date " +
+                            "[file=" + _desc.destFile + "].");
+            }
+        }
+    }
+
+    /**
+     * Downloads the content from the supplied URL connection into the
+     * specified destination file, informing the supplied download manager
+     * and observer of our progress along the way.
+     */
+    protected void downloadContent (DownloadManager dmgr, DownloadObserver obs,
+                                    ProgressInfo pinfo, byte[] buffer,
+                                    URLConnection ucon, File destFile)
+        throws IOException
+    {
+        InputStream in = ucon.getInputStream();
+        FileOutputStream out = new FileOutputStream(destFile);
+        int read;
+
+        // read in the file data
+        while ((read = in.read(buffer)) != -1) {
+            // write it out to our local copy
+            out.write(buffer, 0, read);
+
+            // report our progress to the download observer as a
+            // percentage of the total file data to be transferred
+            pinfo.currentSize += read;
+
+            // update our percent completion; if we're totally done, hold
+            // off on notifying the observer until the download manager
+            // finishes fiddling to ensure that any action the observer
+            // may take on the downloaded files can be safely undertaken
+            int pctdone = pinfo.getPercentDone();
+            pinfo.complete = (pctdone >= 100);
+            if (pinfo.complete) {
+                continue;
+            }
+
+            // update the transfer rate to reflect the bit of data we just
+            // transferred
+            long now = System.currentTimeMillis();
+            pinfo.updateXferRate(now);
+
+            // notify the progress observer if it's been sufficiently long
+            // since our last notification
+            if ((now - pinfo.lastUpdate) >= UPDATE_DELAY) {
+                pinfo.lastUpdate = now;
+                long remaining = pinfo.getXferTimeRemaining();
+                dmgr.notifyProgress(obs, pctdone, remaining);
+            }
+        }
+
+        // close the streams
+        in.close();
+        out.close();
+    }
+
+    /** The descriptor that we're downloading. */
+    protected DownloadDescriptor _desc;
+
+    /** The last-modified difference in milliseconds allowed between the
+     * source and destination file without considering the destination
+     * file to be out of date. */
+    protected static final long DELTA = 5000L;
+
+    /** The delay in milliseconds between notifying progress observers of
+     * file download progress. */
+    protected static final long UPDATE_DELAY = 2500L;
+}