/**
* Returns known active commands in an unmodifiable list. The list contains at most {@link
* #MAX_COMMANDS_SIZE} elements from the command database. It is safe to call it frequently.
* Threads should care of synchronization when iterating over the it.
*/
public synchronized List getCommands() {
List o = commandCollection;
if (o == null) {
o = Collections.unmodifiableList(new ArrayList(commands.keySet()));
commandCollection = o;
}
return o;
}
/**
* Returns known contributions in an unmodifiable list. The list contains at most {@link
* #MAX_CACHE_SIZE} random elements from the contribution repository. Might return the same list
* when called again if there is two little time between the calls. The dynamic type of elements
* is ContributionBox. It is safe to call it frequently. Threads should care of synchronization
* when iterating over it.
*/
public synchronized List getContributions() {
List o = cacheCollection;
if (o == null) {
o = Collections.unmodifiableList(new ArrayList(cache.values()));
cacheCollection = o;
}
return o;
}
/**
* Removes randomly chosen entries until from the cache and commands until the size is not larger
* than MAX_CACHE_SIZE and MAX_COMMANDS_SIZE respectively.
*/
private void cutToSize() {
if (MAX_CACHE_SIZE < cache.size())
synchronized (cache) {
Vector keyList = new Vector(cache.keySet());
Collections.shuffle(keyList);
while (MAX_CACHE_SIZE < cache.size()) {
cache.remove(keyList.get(0));
keyList.remove(0);
}
}
if (MAX_COMMANDS_SIZE < commands.size())
synchronized (commands) {
Vector keyList = new Vector(commands.keySet());
Collections.shuffle(keyList);
while (MAX_COMMANDS_SIZE < commands.size()) {
commands.remove(keyList.get(0));
keyList.remove(0);
}
}
}
/**
* Initiates an information exchange with a known and living other base if such a base exists.
*
* @return true if refresh was succesful, false otherwise.
*/
private boolean refresh() {
final String logSender = observer + "#refresh";
final String contrName = ((contributor != null) ? contributor.getName() : null);
// --- refreshing local contribution and commands
updateLocalInfo();
// --- creating a random permutation of peers
Vector peers = null;
synchronized (cache) {
peers = new Vector(cache.values());
// just to be sure, shouldn't be there anyway
if (contrName != null) peers.remove(cache.get(contrName));
}
Collections.shuffle(peers);
if (peers.isEmpty()) {
Logger.debug(logSender, "no peers in cache");
return false;
}
// --- reset array representations
cacheCollection = null;
commandCollection = null;
// --- trying to talk to random peer
IRequest answer = null;
Address peer = null;
for (int i = 0; i < peers.size(); ++i) {
if (!shouldLive) return false;
peer = ((ContributionBox) peers.get(i)).contributor;
Logger.debug(logSender, "asking " + peer);
answer = observer.fireMessage(peer, "collectiveUpdate-" + name, this);
while (answer.getStatus() == IRequest.WAITING) {
try {
Thread.sleep(100);
} catch (Exception e) {
}
}
if (answer.getStatus() == IRequest.DONE) break;
Logger.debug(logSender, "not accessable: " + peer);
}
if (answer.getStatus() != IRequest.DONE) {
Logger.debug(logSender, "no accessable peers");
observer.collectiveUpdated(null);
return false;
} else {
Collective c = (Collective) answer.getInfo("reply");
// --- remove possible garbage
if (contributor != null) {
cache.remove(contributor.getName());
c.cache.remove(contributor.getName());
}
cache.remove(peer.name);
c.cache.remove(peer.name);
repairSenderAddress(c, peer);
merge(c);
observer.collectiveUpdated((ContributionBox) cache.get(c.myContribution.contributor.name));
return true;
}
}
