/**
* Download an artifact from a host to the cache.
*
* @param host the remote host
* @param artifact the artifact being retrieved
* @param destination the cached destination
* @return TRUE if downloaded
* @exception IOException if an IO error occurs
* @exception TransitException if a transit system error occurs
*/
private boolean download(ResourceHost host, Artifact artifact, File destination)
throws IOException, TransitException {
if (host == null) {
return false;
}
CacheMonitorRouter monitor = Transit.getInstance().getCacheMonitorRouter();
File parentDir = destination.getParentFile();
File tempFile = File.createTempFile("~dpml", ".tmp", parentDir);
tempFile.deleteOnExit(); // safety harness in case we abort abnormally
FileOutputStream tempOut = new FileOutputStream(tempFile);
try {
Date lastModified = host.download(artifact, tempOut);
// An atomic operation and no risk of a corrupted
// artifact content.
tempFile.renameTo(destination);
destination.setLastModified(lastModified.getTime());
return true;
} catch (Throwable e) {
tempFile.delete();
if (monitor != null) {
monitor.failedDownloadFromHost(host.toString(), artifact, e);
}
return false;
}
}
/**
* Find any host.
*
* @param artifact the artifact
* @return the resource host (possibly null)
*/
private ResourceHost findAnyPresence(Artifact artifact) {
synchronized (m_resourceHosts) {
Iterator list = m_resourceHosts.values().iterator();
while (list.hasNext()) {
ResourceHost host = (ResourceHost) list.next();
if (host.isEnabled()) {
if (host.checkPresence(artifact, false)) {
return host;
}
}
}
return null;
}
}
