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Lock all read/writes of selected keys via the public key set #147

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Lock all read/writes of selected keys via the public key set #147

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6818639
Fix file descriptor leak under high concurrency
ThePumpingLemma Oct 28, 2023
51636c7
Lock all read/writes of selected keys via the public key set
ThePumpingLemma Nov 8, 2023
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20 changes: 0 additions & 20 deletions junixsocket-common/src/main/java/org/newsclub/net/unix/AFSelectionKey.java
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Original file line number Diff line number Diff line change
Expand Up @@ -66,18 +66,10 @@ public boolean isValid() {
return !hasOpInvalid() && !cancelled.get() && chann.isOpen() && sel.isOpen();
}

boolean isCancelled() {
return cancelled.get();
}

boolean hasOpInvalid() {
return (opsReady & OP_INVALID) != 0;
}

boolean isSelected() {
return readyOps() != 0;
}

@Override
public void cancel() {
if (!cancelled.compareAndSet(false, true) || !chann.isOpen()) {
Expand All @@ -86,18 +78,6 @@ public void cancel() {
sel.prepareRemove(this);
}

void cancelNoRemove() {
if (!cancelled.compareAndSet(false, true) || !chann.isOpen()) {
return;
}

cancel1();
}

private void cancel1() {
// FIXME
}

@Override
public int interestOps() {
return ops;
Expand Down
158 changes: 87 additions & 71 deletions junixsocket-common/src/main/java/org/newsclub/net/unix/AFSelector.java
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Original file line number Diff line number Diff line change
Expand Up @@ -28,7 +28,9 @@
import java.nio.channels.Selector;
import java.nio.channels.spi.AbstractSelectableChannel;
import java.nio.channels.spi.AbstractSelector;
import java.util.ArrayDeque;
import java.util.Collections;
import java.util.Deque;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Map;
Expand All @@ -49,7 +51,8 @@ final class AFSelector extends AbstractSelector {

private final Set<SelectionKey> selectedKeysSet = new HashSet<>();
private final Set<SelectionKey> selectedKeysPublic = new UngrowableSet<>(selectedKeysSet);
private final Set<SelectionKey> cancelledKeysSet = new HashSet<>();

private final Deque<SelectionKey> cancelledKeys = new ArrayDeque<>();

private PollFd pollFd = null;

Expand Down Expand Up @@ -113,8 +116,10 @@ private int select0(int timeout) throws IOException {
throw new ClosedSelectorException();
}
pfd = pollFd = initPollFd(pollFd);
performRemove();
selectedKeysSet.clear();
synchronized (selectedKeysPublic) {
performRemove();
selectedKeysPublic.clear();
}
}
int num;
try {
Expand All @@ -124,7 +129,6 @@ private int select0(int timeout) throws IOException {
end();
}
synchronized (this) {
selectedKeysSet.clear();
pfd = pollFd;
if (pfd != null) {
AFSelectionKey[] keys = pfd.keys;
Expand All @@ -139,15 +143,24 @@ private int select0(int timeout) throws IOException {
}
}
}

if (num > 0) {
consumeAllBytesAfterPoll();
setOpsReady(pfd); // updates keysSelected and numKeysSelected
}
return selectedKeysSet.size();

synchronized (selectedKeysPublic) {
selectedKeysPublic.clear();
if (num > 0) {
setOpsReady(pfd); // updates keysSelected and numKeysSelected
}
return selectedKeysPublic.size();
}
}
}

private synchronized void consumeAllBytesAfterPoll() throws IOException {
private void consumeAllBytesAfterPoll() throws IOException {
assert Thread.holdsLock(this);

if (pollFd == null) {
return;
}
Expand Down Expand Up @@ -181,80 +194,86 @@ private synchronized void consumeAllBytesAfterPoll() throws IOException {
}
}

private synchronized void setOpsReady(PollFd pfd) {
private void setOpsReady(PollFd pfd) {
assert Thread.holdsLock(this);
assert Thread.holdsLock(selectedKeysPublic);

if (pfd != null) {
for (int i = 1; i < pfd.rops.length; i++) {
int rops = pfd.rops[i];
AFSelectionKey key = pfd.keys[i];
key.setOpsReady(rops);
if (rops != 0 && key.isValid()) {
if (rops != 0) {
selectedKeysSet.add(key);
}
if (!key.isValid()) {
key.cancel();
}
}
}
}

@SuppressWarnings({"resource", "PMD.CognitiveComplexity"})
private PollFd initPollFd(PollFd existingPollFd) throws IOException {
synchronized (this) {
for (Iterator<AFSelectionKey> it = keysRegisteredKeySet.iterator(); it.hasNext();) {
AFSelectionKey key = it.next();
if (!key.getAFCore().fd.valid() || key.hasOpInvalid()) {
key.cancelNoRemove();
it.remove();
existingPollFd = null;
} else {
key.setOpsReady(0);
}
assert Thread.holdsLock(this);

for (Iterator<AFSelectionKey> it = keysRegisteredKeySet.iterator(); it.hasNext();) {
AFSelectionKey key = it.next();
if (!key.getAFCore().fd.valid() || !key.isValid()) {
key.cancel();
it.remove();
existingPollFd = null;
} else {
key.setOpsReady(0);
}
}

if (existingPollFd != null && //
existingPollFd.keys != null && //
(existingPollFd.keys.length - 1) == keysRegistered.size()) {
boolean needsUpdate = false;
int i = 1;
for (AFSelectionKey key : keysRegisteredKeySet) {
if (existingPollFd.keys[i] != key || !key.isValid()) { // NOPMD
needsUpdate = true;
break;
}
existingPollFd.ops[i] = key.interestOps();

i++;
if (existingPollFd != null && //
existingPollFd.keys != null && //
(existingPollFd.keys.length - 1) == keysRegistered.size()) {
boolean needsUpdate = false;
int i = 1;
for (AFSelectionKey key : keysRegisteredKeySet) {
if (existingPollFd.keys[i] != key || !key.isValid()) { // NOPMD
needsUpdate = true;
break;
}
existingPollFd.ops[i] = key.interestOps();

if (!needsUpdate) {
return existingPollFd;
}
i++;
}

int keysToPoll = keysRegistered.size();
for (AFSelectionKey key : keysRegisteredKeySet) {
if (!key.isValid()) {
keysToPoll--;
}
if (!needsUpdate) {
return existingPollFd;
}
}

int size = keysToPoll + 1;
FileDescriptor[] fds = new FileDescriptor[size];
int[] ops = new int[size];
int keysToPoll = keysRegistered.size();
for (AFSelectionKey key : keysRegisteredKeySet) {
if (!key.isValid()) {
keysToPoll--;
}
}

AFSelectionKey[] keys = new AFSelectionKey[size];
fds[0] = selectorPipe.sourceFD();
ops[0] = SelectionKey.OP_READ;
int size = keysToPoll + 1;
FileDescriptor[] fds = new FileDescriptor[size];
int[] ops = new int[size];

int i = 1;
for (AFSelectionKey key : keysRegisteredKeySet) {
if (!key.isValid()) {
continue;
}
keys[i] = key;
fds[i] = key.getAFCore().fd;
ops[i] = key.interestOps();
i++;
AFSelectionKey[] keys = new AFSelectionKey[size];
fds[0] = selectorPipe.sourceFD();
ops[0] = SelectionKey.OP_READ;

int i = 1;
for (AFSelectionKey key : keysRegisteredKeySet) {
if (!key.isValid()) {
continue;
}
return new PollFd(keys, fds, ops);
keys[i] = key;
fds[i] = key.getAFCore().fd;
ops[i] = key.interestOps();
i++;
}
return new PollFd(keys, fds, ops);
}

@Override
Expand All @@ -263,11 +282,11 @@ protected void implCloseSelector() throws IOException {
Set<SelectionKey> keys;
synchronized (this) {
keys = keys();
for (SelectionKey key : keys) {
key.cancel();
}
keysRegistered.clear();
}
for (SelectionKey key : keys) {
((AFSelectionKey) key).cancelNoRemove();
}
selectorPipe.close();
}

Expand Down Expand Up @@ -295,26 +314,23 @@ public Selector wakeup() {
return this;
}

synchronized void remove(AFSelectionKey key) {
selectedKeysSet.remove(key);
deregister(key);
pollFd = null;
}

void prepareRemove(AFSelectionKey key) {
synchronized (cancelledKeysSet) {
cancelledKeysSet.add(key);
synchronized (cancelledKeys) {
cancelledKeys.addLast(key);
}
}

void performRemove() {
synchronized (cancelledKeysSet) {
for (SelectionKey key : cancelledKeysSet) {
selectedKeysSet.remove(key);
assert Thread.holdsLock(this);
assert Thread.holdsLock(selectedKeysPublic);

synchronized (cancelledKeys) {
SelectionKey key;
while ((key = cancelledKeys.pollFirst()) != null) {
selectedKeysPublic.remove(key);
deregister((AFSelectionKey) key);
pollFd = null;
}
cancelledKeysSet.clear();
}
}

Expand Down