Skip to content

binder: synchronize in-use stream updates #12458

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
wants to merge 2 commits into
base: master
Choose a base branch
from
Open

binder: synchronize in-use stream updates #12458

Changes from 1 commit
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
8a7f1cc
binder: fix race between newStream() and unregisterInbound() by synch…
becomeStar Oct 31, 2025
e32c264
fix: avoid potential deadlock by scheduling listener notifications ou…
becomeStar Nov 5, 2025
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
43 changes: 33 additions & 10 deletions binder/src/main/java/io/grpc/binder/internal/BinderClientTransport.java
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -57,7 +57,7 @@
import io.grpc.internal.StatsTraceContext;
import java.util.concurrent.Executor;
import java.util.concurrent.ScheduledFuture;
import java.util.concurrent.atomic.AtomicInteger;

import javax.annotation.Nullable;
import javax.annotation.concurrent.ThreadSafe;

Expand All @@ -73,7 +73,12 @@ public final class BinderClientTransport extends BinderTransport
private final Bindable serviceBinding;

/** Number of ongoing calls which keep this transport "in-use". */
private final AtomicInteger numInUseStreams;
@GuardedBy("this")
private int numInUseStreams;

/** Last in-use state that was reported to the listener */
@GuardedBy("this")
private boolean listenerInUse;

private final long readyTimeoutMillis;
private final PingTracker pingTracker;
Expand Down Expand Up @@ -114,7 +119,8 @@ public BinderClientTransport(
Boolean preAuthServerOverride = options.getEagAttributes().get(PRE_AUTH_SERVER_OVERRIDE);
this.preAuthorizeServer =
preAuthServerOverride != null ? preAuthServerOverride : factory.preAuthorizeServers;
numInUseStreams = new AtomicInteger();
numInUseStreams = 0;
listenerInUse = false;
pingTracker = new PingTracker(Ticker.systemTicker(), (id) -> sendPing(id));

serviceBinding =
Expand Down Expand Up @@ -259,9 +265,7 @@ public synchronized ClientStream newStream(
return newFailingClientStream(failure, attributes, headers, tracers);
}

if (inbound.countsForInUse() && numInUseStreams.getAndIncrement() == 0) {
clientTransportListener.transportInUse(true);
}
updateInUseStreamsIfNeed(inbound.countsForInUse(), 1);
Outbound.ClientOutbound outbound =
new Outbound.ClientOutbound(this, callId, method, headers, statsTraceContext);
if (method.getType().clientSendsOneMessage()) {
Expand All @@ -273,9 +277,7 @@ public synchronized ClientStream newStream(

@Override
protected void unregisterInbound(Inbound<?> inbound) {
if (inbound.countsForInUse() && numInUseStreams.decrementAndGet() == 0) {
clientTransportListener.transportInUse(false);
}
updateInUseStreamsIfNeed(inbound.countsForInUse(), -1);
Copy link
Member

@jdcormie jdcormie Nov 4, 2025

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Please see "A note on synchronization" at the top of BinderTransport.java. Note that unregisterInbound() is called from Inbound.java's synchronized closeAbnormal() and deliverSuffix() methods (via unregister()) Is your proposed lock acquisition order safe or does it risk deadlock?

Copy link
Contributor Author

@becomeStar becomeStar Nov 5, 2025

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Hello @jdcormie
I’ve updated the PR to address the potential deadlock you mentioned in “A note on synchronization” in BinderTransport.java.
I think the fix ensures listener notifications are executed outside the transport lock via the scheduled executor to maintain safe lock ordering.
I also updated the PR title and description to better reflect the changes, and formatted the code using google-java-format.
Could you please take a look when you have a moment? I’d really appreciate your review and feedback.

super.unregisterInbound(inbound);
}

Expand Down Expand Up @@ -305,7 +307,9 @@ void notifyShutdown(Status status) {
@Override
@GuardedBy("this")
void notifyTerminated() {
if (numInUseStreams.getAndSet(0) > 0) {
if(numInUseStreams > 0) {
Copy link
Member

@jdcormie jdcormie Nov 4, 2025

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Please format this code according to the style guide: https://google.github.io/styleguide/javaguide.html I recommend the https://github.com/google/google-java-format tool

numInUseStreams = 0;
listenerInUse = false;
clientTransportListener.transportInUse(false);
}
if (readyTimeoutFuture != null) {
Expand Down Expand Up @@ -391,6 +395,25 @@ private synchronized void handleAuthResult(Throwable t) {
Status.INTERNAL.withDescription("Could not evaluate SecurityPolicy").withCause(t), true);
}

/** Updates in-use-stream count and notifies listener only on transitions between 0 and >0 */
private synchronized void updateInUseStreamsIfNeed(boolean countsForInUse, int delta) {
if(!countsForInUse) {
return;
}

numInUseStreams += delta;
if(numInUseStreams < 0) {
// Defensive: prevent negative due to unexpected double-decrement
numInUseStreams = 0;
}

boolean nowInUseStream = numInUseStreams > 0;
if(nowInUseStream != listenerInUse) {
listenerInUse = nowInUseStream;
clientTransportListener.transportInUse(nowInUseStream);
}
}

@GuardedBy("this")
@Override
protected void handlePingResponse(Parcel parcel) {
Expand Down
Loading