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/*******************************************************************************
* ___ _ ____ ____
* / _ \ _ _ ___ ___| |_| _ \| __ )
* | | | | | | |/ _ \/ __| __| | | | _ \
* | |_| | |_| | __/\__ \ |_| |_| | |_) |
* \__\_\\__,_|\___||___/\__|____/|____/
*
* Copyright (c) 2014-2019 Appsicle
* Copyright (c) 2019-2020 QuestDB
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
******************************************************************************/
package io.questdb.network;
public class IODispatcherLinux extends AbstractIODispatcher {
private static final int M_ID = 2;
private final Epoll epoll;
private long fdid = 1;
public IODispatcherLinux(
IODispatcherConfiguration configuration,
IOContextFactory ioContextFactory
) {
super(configuration, ioContextFactory);
this.epoll = new Epoll(configuration.getEpollFacade(), configuration.getEventCapacity());
this.epoll.listen(serverFd);
logSuccess(configuration);
}
private void enqueuePending(int watermark) {
for (int i = watermark, sz = pending.size(), offset = 0; i < sz; i++, offset += EpollAccessor.SIZEOF_EVENT) {
epoll.setOffset(offset);
if (
epoll.control(
(int) pending.get(i, M_FD),
pending.get(i, M_ID),
EpollAccessor.EPOLL_CTL_ADD,
initialBias == IODispatcherConfiguration.BIAS_READ ? EpollAccessor.EPOLLIN : EpollAccessor.EPOLLOUT
) < 0) {
LOG.debug().$("epoll_ctl failure ").$(nf.errno()).$();
}
}
}
@Override
public void close() {
super.close();
this.epoll.close();
LOG.info().$("closed").$();
}
@Override
protected void pendingAdded(int index) {
pending.set(index, M_ID, fdid++);
}
private void processIdleConnections(long deadline) {
int count = 0;
for (int i = 0, n = pending.size(); i < n && pending.get(i, M_TIMESTAMP) < deadline; i++, count++) {
doDisconnect(pending.get(i));
}
pending.zapTop(count);
}
private boolean processRegistrations(long timestamp) {
long cursor;
int offset = 0;
while ((cursor = interestSubSeq.next()) > -1) {
IOEvent evt = interestQueue.get(cursor);
C context = evt.context;
int operation = evt.operation;
interestSubSeq.done(cursor);
int fd = (int) context.getFd();
final long id = fdid++;
// we re-arm epoll globally, in that even when we disconnect
// because we have to remove FD from epoll
LOG.debug().$("registered [fd=").$(fd).$(", op=").$(operation).$(", id=").$(id).$(']').$();
epoll.setOffset(offset);
if (epoll.control(fd, id, EpollAccessor.EPOLL_CTL_MOD, operation == IOOperation.READ ? EpollAccessor.EPOLLIN : EpollAccessor.EPOLLOUT) < 0) {
System.out.println("oops2: " + nf.errno());
}
offset += EpollAccessor.SIZEOF_EVENT;
int r = pending.addRow();
pending.set(r, M_TIMESTAMP, timestamp);
pending.set(r, M_FD, fd);
pending.set(r, M_ID, id);
pending.set(r, context);
}
if (offset > 0) {
LOG.debug().$("reg").$();
}
return offset > 0;
}
@Override
protected boolean runSerially() {
// todo: introduce fairness factor
// current worker impl will still proceed to execute another job even if this one was useful
// we should see if we can stay inside of this method until we have a completely idle iteration
// at the same time we should hog this thread in case we are always 'useful', we can probably
// introduce a loop count after which we always exit
boolean useful = false;
processDisconnects();
final long timestamp = clock.getTicks();
final int n = epoll.poll();
int watermark = pending.size();
int offset = 0;
if (n > 0) {
// check all activated FDs
LOG.debug().$("epoll [n=").$(n).$(']').$();
for (int i = 0; i < n; i++) {
epoll.setOffset(offset);
offset += EpollAccessor.SIZEOF_EVENT;
final long id = epoll.getData();
// this is server socket, accept if there aren't too many already
if (id == 0) {
accept(timestamp);
} else {
// find row in pending for two reasons:
// 1. find payload
// 2. remove row from pending, remaining rows will be timed out
int row = pending.binarySearch(id, M_ID);
if (row < 0) {
LOG.error().$("internal error: epoll returned unexpected id [id=").$(id).$(']').$();
continue;
}
publishOperation(
(epoll.getEvent() & EpollAccessor.EPOLLIN) > 0 ? IOOperation.READ : IOOperation.WRITE,
pending.get(row)
);
pending.deleteRow(row);
watermark--;
}
}
// process rows over watermark
if (watermark < pending.size()) {
enqueuePending(watermark);
}
useful = true;
}
// process timed out connections
final long deadline = timestamp - idleConnectionTimeout;
if (pending.size() > 0 && pending.get(0, M_TIMESTAMP) < deadline) {
processIdleConnections(deadline);
useful = true;
}
return processRegistrations(timestamp) || useful;
}
}
