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Pure Java implementation of libzmq
/*
Copyright (c) 2007-2014 Contributors as noted in the AUTHORS file
This file is part of 0MQ.
0MQ is free software; you can redistribute it and/or modify it under
the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
0MQ is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with this program. If not, see sockets;
// List of unused thread slots.
private final Deque emptySlots;
// If true, init has been called but no socket has been created
// yet. Launching of I/O threads is delayed.
private AtomicBoolean starting = new AtomicBoolean(true);
// If true, zmq_term was already called.
private boolean terminating;
// Synchronisation of accesses to global slot-related data:
// sockets, emptySlots, terminating. It also synchronises
// access to zombie sockets as such (as opposed to slots) and provides
// a memory barrier to ensure that all CPU cores see the same data.
private final Lock slotSync;
// The reaper thread.
private Reaper reaper;
// I/O threads.
private final List ioThreads;
// Array of pointers to mailboxes for both application and I/O threads.
private int slotCount;
private Mailbox[] slots;
// Mailbox for zmq_term thread.
private final Mailbox termMailbox;
// List of inproc endpoints within this context.
private final Map endpoints;
// Synchronisation of access to the list of inproc endpoints.
private final Lock endpointsSync;
// Maximum socket ID.
private static AtomicInteger maxSocketId = new AtomicInteger(0);
// Maximum number of sockets that can be opened at the same time.
private int maxSockets;
// Number of I/O threads to launch.
private int ioThreadCount;
// Does context wait (possibly forever) on termination?
private boolean blocky;
// Synchronisation of access to context options.
private final Lock optSync;
public static final int TERM_TID = 0;
public static final int REAPER_TID = 1;
public Ctx()
{
tag = 0xabadcafe;
terminating = false;
reaper = null;
slotCount = 0;
slots = null;
maxSockets = ZMQ.ZMQ_MAX_SOCKETS_DFLT;
ioThreadCount = ZMQ.ZMQ_IO_THREADS_DFLT;
blocky = true;
slotSync = new ReentrantLock();
endpointsSync = new ReentrantLock();
optSync = new ReentrantLock();
termMailbox = new Mailbox("terminater");
emptySlots = new ArrayDeque();
ioThreads = new ArrayList();
sockets = new ArrayList();
endpoints = new HashMap();
}
private void destroy() throws IOException
{
for (IOThread it : ioThreads) {
it.stop();
}
for (IOThread it : ioThreads) {
it.close();
}
if (reaper != null) {
reaper.close();
}
termMailbox.close();
tag = 0xdeadbeef;
}
// Returns false if object is not a context.
public boolean checkTag()
{
return tag == 0xabadcafe;
}
// This function is called when user invokes zmq_term. If there are
// no more sockets open it'll cause all the infrastructure to be shut
// down. If there are open sockets still, the deallocation happens
// after the last one is closed.
public void terminate()
{
tag = 0xdeadbeef;
if (!starting.get()) {
slotSync.lock();
try {
// Check whether termination was already underway, but interrupted and now
// restarted.
boolean restarted = terminating;
terminating = true;
// First attempt to terminate the context.
if (!restarted) {
// First send stop command to sockets so that any blocking calls
// can be interrupted. If there are no sockets we can ask reaper
// thread to stop.
for (SocketBase socket : sockets) {
socket.stop();
}
if (sockets.isEmpty()) {
reaper.stop();
}
}
}
finally {
slotSync.unlock();
}
// Wait till reaper thread closes all the sockets.
Command cmd = termMailbox.recv(-1);
if (cmd == null) {
throw new IllegalStateException();
}
assert (cmd.type() == Command.Type.DONE);
slotSync.lock();
try {
assert (sockets.isEmpty());
}
finally {
slotSync.unlock();
}
}
// Deallocate the resources.
try {
destroy();
}
catch (IOException e) {
throw new RuntimeException(e);
}
}
public boolean set(int option, int optval)
{
if (option == ZMQ.ZMQ_MAX_SOCKETS && optval >= 1) {
optSync.lock();
try {
maxSockets = optval;
}
finally {
optSync.unlock();
}
}
else
if (option == ZMQ.ZMQ_IO_THREADS && optval >= 0) {
optSync.lock();
try {
ioThreadCount = optval;
}
finally {
optSync.unlock();
}
}
else
if (option == ZMQ.ZMQ_BLOCKY && optval >= 0) {
optSync.lock();
try {
blocky = (optval != 0);
}
finally {
optSync.unlock();
}
}
else {
return false;
}
return true;
}
public int get(int option)
{
int rc = 0;
if (option == ZMQ.ZMQ_MAX_SOCKETS) {
rc = maxSockets;
}
else if (option == ZMQ.ZMQ_IO_THREADS) {
rc = ioThreadCount;
}
else if (option == ZMQ.ZMQ_BLOCKY) {
rc = blocky ? 1 : 0;
}
else {
throw new IllegalArgumentException("option = " + option);
}
return rc;
}
public SocketBase createSocket(int type)
{
SocketBase s = null;
slotSync.lock();
try {
if (starting.compareAndSet(true, false)) {
// Initialize the array of mailboxes. Additional three slots are for
// zmq_term thread and reaper thread.
int mazmq;
int ios;
optSync.lock();
try {
mazmq = maxSockets;
ios = ioThreadCount;
}
finally {
optSync.unlock();
}
slotCount = mazmq + ios + 2;
slots = new Mailbox[slotCount];
//alloc_assert (slots);
// Initialize the infrastructure for zmq_term thread.
slots[TERM_TID] = termMailbox;
// Create the reaper thread.
reaper = new Reaper(this, REAPER_TID);
//alloc_assert (reaper);
slots[REAPER_TID] = reaper.getMailbox();
reaper.start();
// Create I/O thread objects and launch them.
for (int i = 2; i != ios + 2; i++) {
IOThread ioThread = new IOThread(this, i);
//alloc_assert (io_thread);
ioThreads.add(ioThread);
slots[i] = ioThread.getMailbox();
ioThread.start();
}
// In the unused part of the slot array, create a list of empty slots.
for (int i = (int) slotCount - 1;
i >= (int) ios + 2; i--) {
emptySlots.add(i);
slots[i] = null;
}
}
// Once zmq_term() was called, we can't create new sockets.
if (terminating) {
throw new ZError.CtxTerminatedException();
}
// If maxSockets limit was reached, return error.
if (emptySlots.isEmpty()) {
throw new IllegalStateException("EMFILE");
}
// Choose a slot for the socket.
int slot = emptySlots.pollLast();
// Generate new unique socket ID.
int sid = maxSocketId.incrementAndGet();
// Create the socket and register its mailbox.
s = SocketBase.create(type, this, slot, sid);
if (s == null) {
emptySlots.addLast(slot);
return null;
}
sockets.add(s);
slots[slot] = s.getMailbox();
}
finally {
slotSync.unlock();
}
return s;
}
public void destroySocket(SocketBase socket)
{
slotSync.lock();
// Free the associated thread slot.
try {
int tid = socket.getTid();
emptySlots.add(tid);
slots[tid] = null;
// Remove the socket from the list of sockets.
sockets.remove(socket);
// If zmq_term() was already called and there are no more socket
// we can ask reaper thread to terminate.
if (terminating && sockets.isEmpty()) {
reaper.stop();
}
}
finally {
slotSync.unlock();
}
}
// Returns reaper thread object.
ZObject getReaper()
{
return reaper;
}
// Send command to the destination thread.
void sendCommand(int tid, final Command command)
{
slots[tid].send(command);
}
// Returns the I/O thread that is the least busy at the moment.
// Affinity specifies which I/O threads are eligible (0 = all).
// Returns NULL if no I/O thread is available.
IOThread chooseIoThread(long affinity)
{
if (ioThreads.isEmpty()) {
return null;
}
// Find the I/O thread with minimum load.
int minLoad = -1;
IOThread selectedIoThread = null;
for (int i = 0; i != ioThreads.size(); i++) {
if (affinity == 0 || (affinity & (1L << i)) > 0) {
int load = ioThreads.get(i).getLoad();
if (selectedIoThread == null || load < minLoad) {
minLoad = load;
selectedIoThread = ioThreads.get(i);
}
}
}
return selectedIoThread;
}
// Management of inproc endpoints.
boolean registerEndpoint(String addr, Endpoint endpoint)
{
endpointsSync.lock();
Endpoint inserted = null;
try {
inserted = endpoints.put(addr, endpoint);
}
finally {
endpointsSync.unlock();
}
if (inserted != null) {
return false;
}
return true;
}
void unregisterEndpoints(SocketBase socket)
{
endpointsSync.lock();
try {
Iterator> it = endpoints.entrySet().iterator();
while (it.hasNext()) {
Entry e = it.next();
if (e.getValue().socket == socket) {
it.remove();
}
}
}
finally {
endpointsSync.unlock();
}
}
Endpoint findEndpoint(String addr)
{
Endpoint endpoint = null;
endpointsSync.lock();
try {
endpoint = endpoints.get(addr);
if (endpoint == null) {
//ZError.errno(ZError.ECONNREFUSED);
return new Endpoint(null, new Options());
}
// Increment the command sequence number of the peer so that it won't
// get deallocated until "bind" command is issued by the caller.
// The subsequent 'bind' has to be called with inc_seqnum parameter
// set to false, so that the seqnum isn't incremented twice.
endpoint.socket.incSeqnum();
}
finally {
endpointsSync.unlock();
}
return endpoint;
}
}
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