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package com.diozero.util;
/*
* #%L
* Organisation: diozero
* Project: Device I/O Zero - Core
* Filename: EpollNative.java
*
* This file is part of the diozero project. More information about this project
* can be found at http://www.diozero.com/
* %%
* Copyright (C) 2016 - 2021 diozero
* %%
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
* #L%
*/
import java.io.Closeable;
import java.util.HashMap;
import java.util.Map;
import java.util.Queue;
import java.util.concurrent.ConcurrentLinkedQueue;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;
import org.tinylog.Logger;
import com.diozero.api.RuntimeIOException;
public class EpollNative implements EpollNativeCallback, Closeable {
static {
LibraryLoader.loadSystemUtils();
}
private static native int epollCreate();
private static native int addFile(int epollFd, String filename);
private static native int removeFile(int epollFd, int fileFd);
private static native EpollEvent[] waitForEvents(int epollFd);
private static native int eventLoop(int epollFd, EpollNativeCallback callback);
private static native void stopWait(int epollFd);
private static native void shutdown(int epollFd);
private int epollFd;
private Map fdToListener;
private Map filenameToFd;
private AtomicBoolean running;
private Queue eventQueue;
private Lock lock;
private Condition condition;
public EpollNative() {
fdToListener = new HashMap<>();
filenameToFd = new HashMap<>();
running = new AtomicBoolean(false);
eventQueue = new ConcurrentLinkedQueue<>();
lock = new ReentrantLock();
condition = lock.newCondition();
int rc = epollCreate();
if (rc < 0) {
throw new RuntimeIOException("Error in epollCreate: " + rc);
}
epollFd = rc;
}
private void waitForEvents() {
Thread.currentThread().setName("diozero-EpollNative-waitForEvents-" + hashCode());
if (eventLoop(epollFd, this) < 0) {
throw new RuntimeIOException("Error starting native epoll event loop");
}
/*
while (running.get()) {
EpollEvent[] events = waitForEvents(epollFd);
if (events == null) {
Logger.debug("Got no events");
running.getAndSet(false);
} else {
for (EpollEvent event : events) {
eventQueue.add(event);
}
// Notify the process events thread that there are new events on the queue
lock.lock();
try {
condition.signal();
} finally {
lock.unlock();
}
}
}
*/
Logger.trace("Finished");
}
@Override
public void callback(int fd, int eventMask, long epochTime, long nanoTime, byte value) {
// Notify the process events thread that there are new events on the queue
lock.lock();
eventQueue.add(new EpollEvent(fd, eventMask, epochTime, nanoTime, value));
try {
condition.signal();
} finally {
lock.unlock();
}
}
private void processEvents() {
Thread.currentThread().setName("diozero-EpollNative-processEvents-" + hashCode());
while (running.get()) {
// Wait for an event on the queue
lock.lock();
try {
condition.await();
} catch (InterruptedException e) {
Logger.debug("Interrupted!");
break;
} finally {
lock.unlock();
}
// Process all of the events on the queue
// Note the event queue is a concurrent linked queue hence thread safe
do {
EpollEvent event = eventQueue.poll();
if (event == null) {
Logger.debug("No event returned");
} else {
Integer fd = Integer.valueOf(event.getFd());
PollEventListener listener = fdToListener.get(fd);
if (listener == null) {
Logger.warn("No listener for fd {}, event value: '{}'", fd,
Character.valueOf(event.getValue()));
} else {
listener.notify(event.getEpochTime(), event.getNanoTime(), event.getValue());
}
}
} while (! eventQueue.isEmpty());
}
Logger.debug("Finished");
}
public void register(String filename, PollEventListener listener) {
int file_fd = addFile(epollFd, filename);
if (file_fd == -1) {
throw new RuntimeIOException("Error registering file '" + filename + "' with epoll");
}
fdToListener.put(Integer.valueOf(file_fd), listener);
filenameToFd.put(filename, Integer.valueOf(file_fd));
}
public void deregister(String filename) {
Integer file_fd = filenameToFd.get(filename);
if (file_fd == null) {
Logger.warn("No file descriptor for '{}'", filename);
return;
}
int rc = removeFile(epollFd, file_fd.intValue());
if (rc < 0) {
Logger.warn("Error in epoll removeFile for file fd {}: {}", file_fd, Integer.valueOf(rc));
}
fdToListener.remove(file_fd);
filenameToFd.remove(filename);
}
public void enableEvents() {
running.getAndSet(true);
DiozeroScheduler.getDaemonInstance().execute(this::processEvents);
DiozeroScheduler.getDaemonInstance().execute(this::waitForEvents);
}
public void disableEvents() {
running.getAndSet(false);
// Stop the epoll thread
stopWait(epollFd);
// Wake up the process events thread so that it can exit
lock.lock();
try {
condition.signal();
} finally {
lock.unlock();
}
}
@Override
public void close() {
disableEvents();
shutdown(epollFd);
fdToListener.clear();
filenameToFd.clear();
}
}
