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Posted to notifications@ignite.apache.org by GitBox <gi...@apache.org> on 2023/01/12 13:00:11 UTC
[GitHub] [ignite-3] xtern commented on a diff in pull request #1511: IGNITE-18227: Make composite publisher is thread safe
xtern commented on code in PR #1511:
URL: https://github.com/apache/ignite-3/pull/1511#discussion_r1068051235
##########
modules/sql-engine/src/main/java/org/apache/ignite/internal/sql/engine/util/ConcatPublisher.java:
##########
@@ -0,0 +1,263 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You 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 org.apache.ignite.internal.sql.engine.util;
+
+import java.lang.invoke.MethodHandles;
+import java.lang.invoke.MethodHandles.Lookup;
+import java.lang.invoke.VarHandle;
+import java.util.Iterator;
+import java.util.concurrent.Flow.Publisher;
+import java.util.concurrent.Flow.Subscriber;
+import java.util.concurrent.Flow.Subscription;
+import java.util.concurrent.atomic.AtomicInteger;
+
+
+/**
+ * Thread-safe realization of combine multiple publishers. Generally, start consuming a source once the previous source has terminated,
+ * building a chain.
+ */
+public class ConcatPublisher<T> implements Publisher<T> {
+ /** Iterator of upstream publishers. */
+ private final Iterator<Publisher<? extends T>> sources;
+
+ /**
+ * Constructor.
+ *
+ * @param sources Iterator of upstream publishers.
+ */
+ public ConcatPublisher(Iterator<Publisher<? extends T>> sources) {
+ this.sources = sources;
+ }
+
+ /** {@inheritDoc} */
+ @Override
+ public void subscribe(Subscriber<? super T> downstream) {
+ ConcatCoordinator<T> subscription = new ConcatCoordinator<>(downstream, sources);
+
+ downstream.onSubscribe(subscription);
+ subscription.drain();
+ }
+
+ /**
+ * Concatenation composite subscription.
+ */
+ static final class ConcatCoordinator<T> extends SubscriptionArbiter implements Subscriber<T> {
+ /** Counter to prevent concurrent execution of a critical section. */
+ private final AtomicInteger guardCntr = new AtomicInteger();
+
+ final Subscriber downstream;
+
+ final Iterator<Publisher<? extends T>> sources;
+
+ long consumed;
+
+ ConcatCoordinator(
+ Subscriber downstream,
Review Comment:
```suggestion
Subscriber<? super T> downstream,
```
##########
modules/sql-engine/src/main/java/org/apache/ignite/internal/sql/engine/util/ConcatPublisher.java:
##########
@@ -0,0 +1,263 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You 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 org.apache.ignite.internal.sql.engine.util;
+
+import java.lang.invoke.MethodHandles;
+import java.lang.invoke.MethodHandles.Lookup;
+import java.lang.invoke.VarHandle;
+import java.util.Iterator;
+import java.util.concurrent.Flow.Publisher;
+import java.util.concurrent.Flow.Subscriber;
+import java.util.concurrent.Flow.Subscription;
+import java.util.concurrent.atomic.AtomicInteger;
+
+
+/**
+ * Thread-safe realization of combine multiple publishers. Generally, start consuming a source once the previous source has terminated,
+ * building a chain.
+ */
+public class ConcatPublisher<T> implements Publisher<T> {
+ /** Iterator of upstream publishers. */
+ private final Iterator<Publisher<? extends T>> sources;
+
+ /**
+ * Constructor.
+ *
+ * @param sources Iterator of upstream publishers.
+ */
+ public ConcatPublisher(Iterator<Publisher<? extends T>> sources) {
+ this.sources = sources;
+ }
+
+ /** {@inheritDoc} */
+ @Override
+ public void subscribe(Subscriber<? super T> downstream) {
+ ConcatCoordinator<T> subscription = new ConcatCoordinator<>(downstream, sources);
+
+ downstream.onSubscribe(subscription);
+ subscription.drain();
+ }
+
+ /**
+ * Concatenation composite subscription.
+ */
+ static final class ConcatCoordinator<T> extends SubscriptionArbiter implements Subscriber<T> {
+ /** Counter to prevent concurrent execution of a critical section. */
+ private final AtomicInteger guardCntr = new AtomicInteger();
+
+ final Subscriber downstream;
Review Comment:
```suggestion
final Subscriber<? super T> downstream;
```
##########
modules/sql-engine/src/main/java/org/apache/ignite/internal/sql/engine/util/ConcatPublisher.java:
##########
@@ -0,0 +1,263 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You 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 org.apache.ignite.internal.sql.engine.util;
+
+import java.lang.invoke.MethodHandles;
+import java.lang.invoke.MethodHandles.Lookup;
+import java.lang.invoke.VarHandle;
+import java.util.Iterator;
+import java.util.concurrent.Flow.Publisher;
+import java.util.concurrent.Flow.Subscriber;
+import java.util.concurrent.Flow.Subscription;
+import java.util.concurrent.atomic.AtomicInteger;
+
+
+/**
+ * Thread-safe realization of combine multiple publishers. Generally, start consuming a source once the previous source has terminated,
+ * building a chain.
+ */
+public class ConcatPublisher<T> implements Publisher<T> {
+ /** Iterator of upstream publishers. */
+ private final Iterator<Publisher<? extends T>> sources;
+
+ /**
+ * Constructor.
+ *
+ * @param sources Iterator of upstream publishers.
+ */
+ public ConcatPublisher(Iterator<Publisher<? extends T>> sources) {
+ this.sources = sources;
+ }
+
+ /** {@inheritDoc} */
+ @Override
+ public void subscribe(Subscriber<? super T> downstream) {
+ ConcatCoordinator<T> subscription = new ConcatCoordinator<>(downstream, sources);
+
+ downstream.onSubscribe(subscription);
+ subscription.drain();
+ }
+
+ /**
+ * Concatenation composite subscription.
+ */
+ static final class ConcatCoordinator<T> extends SubscriptionArbiter implements Subscriber<T> {
+ /** Counter to prevent concurrent execution of a critical section. */
+ private final AtomicInteger guardCntr = new AtomicInteger();
+
+ final Subscriber downstream;
+
+ final Iterator<Publisher<? extends T>> sources;
+
+ long consumed;
+
+ ConcatCoordinator(
+ Subscriber downstream,
+ Iterator<Publisher<? extends T>> sources
+ ) {
+ this.downstream = downstream;
+ this.sources = sources;
+ }
+
+ @Override
+ public void onSubscribe(Subscription s) {
+ setSubscription(s);
+ }
+
+ @Override
+ public void onNext(T item) {
+ consumed++;
+ downstream.onNext(item);
+ }
+
+ @Override
+ public void onError(Throwable throwable) {
+ downstream.onError(throwable);
+ }
+
+ @Override
+ public void onComplete() {
+ drain();
+ }
+
+ void drain() {
+ if (guardCntr.getAndIncrement() == 0) {
+ do {
+ if (isCancelled()) {
+ return;
+ }
+
+ if (!sources.hasNext()) {
+ downstream.onComplete();
+ return;
+ }
+
+ long c = consumed;
+ if (c != 0L) {
+ consumed = 0L;
+ setProduced(c);
+ }
+
+ sources.next().subscribe(this);
+
+ } while ((guardCntr.getAndDecrement() - 1) != 0);
+ }
+ }
+ }
+
+ static class SubscriptionArbiter implements Subscription {
+ Subscription current;
+ static final VarHandle CURRENT;
+
+ Subscription next;
+ static final VarHandle NEXT;
+
+ long requested;
+
+ long downstreamRequested;
+ static final VarHandle DOWNSTREAM_REQUESTED;
+
+ long produced;
+ static final VarHandle PRODUCED;
+
+ int wip;
+ static final VarHandle WIP;
Review Comment:
I suggest to replace it with `AtomicInteger` (and may be rename it similar to `guardCnt".
This will simplify the code.
##########
modules/sql-engine/src/main/java/org/apache/ignite/internal/sql/engine/util/ConcatPublisher.java:
##########
@@ -0,0 +1,263 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You 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 org.apache.ignite.internal.sql.engine.util;
+
+import java.lang.invoke.MethodHandles;
+import java.lang.invoke.MethodHandles.Lookup;
+import java.lang.invoke.VarHandle;
+import java.util.Iterator;
+import java.util.concurrent.Flow.Publisher;
+import java.util.concurrent.Flow.Subscriber;
+import java.util.concurrent.Flow.Subscription;
+import java.util.concurrent.atomic.AtomicInteger;
+
+
+/**
+ * Thread-safe realization of combine multiple publishers. Generally, start consuming a source once the previous source has terminated,
+ * building a chain.
+ */
+public class ConcatPublisher<T> implements Publisher<T> {
+ /** Iterator of upstream publishers. */
+ private final Iterator<Publisher<? extends T>> sources;
+
+ /**
+ * Constructor.
+ *
+ * @param sources Iterator of upstream publishers.
+ */
+ public ConcatPublisher(Iterator<Publisher<? extends T>> sources) {
+ this.sources = sources;
+ }
+
+ /** {@inheritDoc} */
+ @Override
+ public void subscribe(Subscriber<? super T> downstream) {
+ ConcatCoordinator<T> subscription = new ConcatCoordinator<>(downstream, sources);
+
+ downstream.onSubscribe(subscription);
+ subscription.drain();
+ }
+
+ /**
+ * Concatenation composite subscription.
+ */
+ static final class ConcatCoordinator<T> extends SubscriptionArbiter implements Subscriber<T> {
+ /** Counter to prevent concurrent execution of a critical section. */
+ private final AtomicInteger guardCntr = new AtomicInteger();
+
+ final Subscriber downstream;
+
+ final Iterator<Publisher<? extends T>> sources;
+
+ long consumed;
+
+ ConcatCoordinator(
+ Subscriber downstream,
+ Iterator<Publisher<? extends T>> sources
+ ) {
+ this.downstream = downstream;
+ this.sources = sources;
+ }
+
+ @Override
+ public void onSubscribe(Subscription s) {
+ setSubscription(s);
+ }
+
+ @Override
+ public void onNext(T item) {
+ consumed++;
+ downstream.onNext(item);
+ }
+
+ @Override
+ public void onError(Throwable throwable) {
+ downstream.onError(throwable);
+ }
+
+ @Override
+ public void onComplete() {
+ drain();
+ }
+
+ void drain() {
+ if (guardCntr.getAndIncrement() == 0) {
+ do {
+ if (isCancelled()) {
+ return;
+ }
+
+ if (!sources.hasNext()) {
+ downstream.onComplete();
+ return;
+ }
+
+ long c = consumed;
+ if (c != 0L) {
+ consumed = 0L;
+ setProduced(c);
+ }
+
+ sources.next().subscribe(this);
+
+ } while ((guardCntr.getAndDecrement() - 1) != 0);
+ }
+ }
+ }
+
+ static class SubscriptionArbiter implements Subscription {
+ Subscription current;
+ static final VarHandle CURRENT;
+
+ Subscription next;
+ static final VarHandle NEXT;
+
+ long requested;
+
+ long downstreamRequested;
+ static final VarHandle DOWNSTREAM_REQUESTED;
Review Comment:
I suggest to replace it with `AtomicLong`.
The code will be cleaner.
##########
modules/sql-engine/src/main/java/org/apache/ignite/internal/sql/engine/util/ConcatPublisher.java:
##########
@@ -0,0 +1,263 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You 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 org.apache.ignite.internal.sql.engine.util;
+
+import java.lang.invoke.MethodHandles;
+import java.lang.invoke.MethodHandles.Lookup;
+import java.lang.invoke.VarHandle;
+import java.util.Iterator;
+import java.util.concurrent.Flow.Publisher;
+import java.util.concurrent.Flow.Subscriber;
+import java.util.concurrent.Flow.Subscription;
+import java.util.concurrent.atomic.AtomicInteger;
+
+
+/**
+ * Thread-safe realization of combine multiple publishers. Generally, start consuming a source once the previous source has terminated,
+ * building a chain.
+ */
+public class ConcatPublisher<T> implements Publisher<T> {
+ /** Iterator of upstream publishers. */
+ private final Iterator<Publisher<? extends T>> sources;
+
+ /**
+ * Constructor.
+ *
+ * @param sources Iterator of upstream publishers.
+ */
+ public ConcatPublisher(Iterator<Publisher<? extends T>> sources) {
+ this.sources = sources;
+ }
+
+ /** {@inheritDoc} */
+ @Override
+ public void subscribe(Subscriber<? super T> downstream) {
+ ConcatCoordinator<T> subscription = new ConcatCoordinator<>(downstream, sources);
+
+ downstream.onSubscribe(subscription);
+ subscription.drain();
+ }
+
+ /**
+ * Concatenation composite subscription.
+ */
+ static final class ConcatCoordinator<T> extends SubscriptionArbiter implements Subscriber<T> {
+ /** Counter to prevent concurrent execution of a critical section. */
+ private final AtomicInteger guardCntr = new AtomicInteger();
+
+ final Subscriber downstream;
+
+ final Iterator<Publisher<? extends T>> sources;
+
+ long consumed;
+
+ ConcatCoordinator(
+ Subscriber downstream,
+ Iterator<Publisher<? extends T>> sources
+ ) {
+ this.downstream = downstream;
+ this.sources = sources;
+ }
+
+ @Override
+ public void onSubscribe(Subscription s) {
+ setSubscription(s);
+ }
+
+ @Override
+ public void onNext(T item) {
+ consumed++;
+ downstream.onNext(item);
+ }
+
+ @Override
+ public void onError(Throwable throwable) {
+ downstream.onError(throwable);
+ }
+
+ @Override
+ public void onComplete() {
+ drain();
+ }
+
+ void drain() {
+ if (guardCntr.getAndIncrement() == 0) {
+ do {
+ if (isCancelled()) {
+ return;
+ }
+
+ if (!sources.hasNext()) {
+ downstream.onComplete();
+ return;
+ }
+
+ long c = consumed;
+ if (c != 0L) {
+ consumed = 0L;
+ setProduced(c);
+ }
+
+ sources.next().subscribe(this);
+
+ } while ((guardCntr.getAndDecrement() - 1) != 0);
+ }
+ }
+ }
+
+ static class SubscriptionArbiter implements Subscription {
Review Comment:
We currently only have one class that inherits from `SubscriptionArbiter`.
It seems we should just combine `ConcatCoordinator` with `SubscriptionArbiter`
##########
modules/sql-engine/src/main/java/org/apache/ignite/internal/sql/engine/util/ConcatPublisher.java:
##########
@@ -0,0 +1,263 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You 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 org.apache.ignite.internal.sql.engine.util;
+
+import java.lang.invoke.MethodHandles;
+import java.lang.invoke.MethodHandles.Lookup;
+import java.lang.invoke.VarHandle;
+import java.util.Iterator;
+import java.util.concurrent.Flow.Publisher;
+import java.util.concurrent.Flow.Subscriber;
+import java.util.concurrent.Flow.Subscription;
+import java.util.concurrent.atomic.AtomicInteger;
+
+
+/**
+ * Thread-safe realization of combine multiple publishers. Generally, start consuming a source once the previous source has terminated,
+ * building a chain.
+ */
+public class ConcatPublisher<T> implements Publisher<T> {
+ /** Iterator of upstream publishers. */
+ private final Iterator<Publisher<? extends T>> sources;
+
+ /**
+ * Constructor.
+ *
+ * @param sources Iterator of upstream publishers.
+ */
+ public ConcatPublisher(Iterator<Publisher<? extends T>> sources) {
+ this.sources = sources;
+ }
+
+ /** {@inheritDoc} */
+ @Override
+ public void subscribe(Subscriber<? super T> downstream) {
+ ConcatCoordinator<T> subscription = new ConcatCoordinator<>(downstream, sources);
+
+ downstream.onSubscribe(subscription);
+ subscription.drain();
+ }
+
+ /**
+ * Concatenation composite subscription.
+ */
+ static final class ConcatCoordinator<T> extends SubscriptionArbiter implements Subscriber<T> {
+ /** Counter to prevent concurrent execution of a critical section. */
+ private final AtomicInteger guardCntr = new AtomicInteger();
+
+ final Subscriber downstream;
+
+ final Iterator<Publisher<? extends T>> sources;
+
+ long consumed;
+
+ ConcatCoordinator(
+ Subscriber downstream,
+ Iterator<Publisher<? extends T>> sources
+ ) {
+ this.downstream = downstream;
+ this.sources = sources;
+ }
+
+ @Override
+ public void onSubscribe(Subscription s) {
+ setSubscription(s);
+ }
+
+ @Override
+ public void onNext(T item) {
+ consumed++;
+ downstream.onNext(item);
+ }
+
+ @Override
+ public void onError(Throwable throwable) {
+ downstream.onError(throwable);
+ }
+
+ @Override
+ public void onComplete() {
+ drain();
+ }
+
+ void drain() {
+ if (guardCntr.getAndIncrement() == 0) {
+ do {
+ if (isCancelled()) {
+ return;
+ }
+
+ if (!sources.hasNext()) {
+ downstream.onComplete();
+ return;
+ }
+
+ long c = consumed;
+ if (c != 0L) {
+ consumed = 0L;
+ setProduced(c);
+ }
+
+ sources.next().subscribe(this);
+
+ } while ((guardCntr.getAndDecrement() - 1) != 0);
Review Comment:
```suggestion
} while (guardCntr.decrementAndGet() != 0);
```
##########
modules/sql-engine/src/main/java/org/apache/ignite/internal/sql/engine/util/ConcatPublisher.java:
##########
@@ -0,0 +1,263 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You 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 org.apache.ignite.internal.sql.engine.util;
+
+import java.lang.invoke.MethodHandles;
+import java.lang.invoke.MethodHandles.Lookup;
+import java.lang.invoke.VarHandle;
+import java.util.Iterator;
+import java.util.concurrent.Flow.Publisher;
+import java.util.concurrent.Flow.Subscriber;
+import java.util.concurrent.Flow.Subscription;
+import java.util.concurrent.atomic.AtomicInteger;
+
+
+/**
+ * Thread-safe realization of combine multiple publishers. Generally, start consuming a source once the previous source has terminated,
+ * building a chain.
+ */
+public class ConcatPublisher<T> implements Publisher<T> {
+ /** Iterator of upstream publishers. */
+ private final Iterator<Publisher<? extends T>> sources;
+
+ /**
+ * Constructor.
+ *
+ * @param sources Iterator of upstream publishers.
+ */
+ public ConcatPublisher(Iterator<Publisher<? extends T>> sources) {
+ this.sources = sources;
+ }
+
+ /** {@inheritDoc} */
+ @Override
+ public void subscribe(Subscriber<? super T> downstream) {
+ ConcatCoordinator<T> subscription = new ConcatCoordinator<>(downstream, sources);
+
+ downstream.onSubscribe(subscription);
+ subscription.drain();
+ }
+
+ /**
+ * Concatenation composite subscription.
+ */
+ static final class ConcatCoordinator<T> extends SubscriptionArbiter implements Subscriber<T> {
+ /** Counter to prevent concurrent execution of a critical section. */
+ private final AtomicInteger guardCntr = new AtomicInteger();
+
+ final Subscriber downstream;
+
+ final Iterator<Publisher<? extends T>> sources;
+
+ long consumed;
+
+ ConcatCoordinator(
+ Subscriber downstream,
+ Iterator<Publisher<? extends T>> sources
+ ) {
+ this.downstream = downstream;
+ this.sources = sources;
+ }
+
+ @Override
+ public void onSubscribe(Subscription s) {
+ setSubscription(s);
+ }
+
+ @Override
+ public void onNext(T item) {
+ consumed++;
+ downstream.onNext(item);
+ }
+
+ @Override
+ public void onError(Throwable throwable) {
+ downstream.onError(throwable);
+ }
+
+ @Override
+ public void onComplete() {
+ drain();
+ }
+
+ void drain() {
+ if (guardCntr.getAndIncrement() == 0) {
+ do {
+ if (isCancelled()) {
+ return;
+ }
+
+ if (!sources.hasNext()) {
+ downstream.onComplete();
+ return;
+ }
+
+ long c = consumed;
+ if (c != 0L) {
+ consumed = 0L;
+ setProduced(c);
+ }
+
+ sources.next().subscribe(this);
+
+ } while ((guardCntr.getAndDecrement() - 1) != 0);
+ }
+ }
+ }
+
+ static class SubscriptionArbiter implements Subscription {
+ Subscription current;
+ static final VarHandle CURRENT;
+
+ Subscription next;
+ static final VarHandle NEXT;
+
+ long requested;
+
+ long downstreamRequested;
+ static final VarHandle DOWNSTREAM_REQUESTED;
+
+ long produced;
+ static final VarHandle PRODUCED;
+
+ int wip;
+ static final VarHandle WIP;
+
+ static {
+ Lookup lk = MethodHandles.lookup();
+
+ try {
+ CURRENT = lk.findVarHandle(SubscriptionArbiter.class, "current", Subscription.class);
+ NEXT = lk.findVarHandle(SubscriptionArbiter.class, "next", Subscription.class);
+ DOWNSTREAM_REQUESTED = lk.findVarHandle(SubscriptionArbiter.class, "downstreamRequested", long.class);
+ PRODUCED = lk.findVarHandle(SubscriptionArbiter.class, "produced", long.class);
+ WIP = lk.findVarHandle(SubscriptionArbiter.class, "wip", int.class);
+
+ } catch (NoSuchFieldException | IllegalAccessException ex) {
+ throw new InternalError(ex);
+ }
+ }
+
+
+ @Override
+ public final void request(long n) {
+ for (; ; ) {
+ long r = (long) DOWNSTREAM_REQUESTED.getAcquire(this);
+ long u = r + n;
+ if (u < 0L) {
+ u = Long.MAX_VALUE;
+ }
+ if (DOWNSTREAM_REQUESTED.compareAndSet(this, r, u)) {
+ arbiterDrain();
+ break;
+ }
+ }
+ }
+
+ @Override
+ public void cancel() {
+ Subscription s = (Subscription) CURRENT.getAndSet(this, this);
+ if (s != null && s != this) {
+ s.cancel();
+ }
+ s = (Subscription) NEXT.getAndSet(this, this);
+ if (s != null && s != this) {
+ s.cancel();
+ }
+ }
+
+ public final boolean isCancelled() {
+ return CURRENT.getAcquire(this) == this;
+ }
+
+ public final void setSubscription(Subscription subscription) {
+ if (NEXT.compareAndSet(this, null, subscription)) {
+ arbiterDrain();
+ } else {
+ subscription.cancel();
+ }
+ }
+
+ public final void setProduced(long n) {
+ PRODUCED.setRelease(this, n);
+ arbiterDrain();
+ }
+
+ final void arbiterDrain() {
+ if ((int) WIP.getAndAdd(this, 1) != 0) {
+ return;
+ }
+
+ Subscription requestFrom = null;
+ long requestAmount = 0L;
+
+ for (; ; ) {
+ Subscription currentSub = (Subscription) CURRENT.getAcquire(this);
+ if (currentSub != this) {
+
+ long req = requested;
+
+ long downstreamReq = (long) DOWNSTREAM_REQUESTED.getAndSet(this, 0L);
+
+ long prod = (long) PRODUCED.getAndSet(this, 0L);
+
+ Subscription nextSub = (Subscription) NEXT.getAcquire(this); // null
+ if (nextSub != null && nextSub != this) {
+ NEXT.compareAndSet(this, nextSub, null);
+ }
+
+ if (downstreamReq != 0L) {
+ req += downstreamReq;
+ if (req < 0L) {
+ req = Long.MAX_VALUE;
+ }
+ }
+
+ if (prod != 0L && req != Long.MAX_VALUE) {
+ req -= prod;
+ }
+
+ requested = req;
+
+ if (nextSub != null && nextSub != this) {
+ requestFrom = nextSub;
+ requestAmount = req;
+ CURRENT.compareAndSet(this, currentSub, nextSub);
+ } else {
+ // (6) --------------------------------------
Review Comment:
do not forgot to remove
##########
modules/sql-engine/src/main/java/org/apache/ignite/internal/sql/engine/util/ConcatPublisher.java:
##########
@@ -0,0 +1,263 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You 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 org.apache.ignite.internal.sql.engine.util;
+
+import java.lang.invoke.MethodHandles;
+import java.lang.invoke.MethodHandles.Lookup;
+import java.lang.invoke.VarHandle;
+import java.util.Iterator;
+import java.util.concurrent.Flow.Publisher;
+import java.util.concurrent.Flow.Subscriber;
+import java.util.concurrent.Flow.Subscription;
+import java.util.concurrent.atomic.AtomicInteger;
+
+
+/**
+ * Thread-safe realization of combine multiple publishers. Generally, start consuming a source once the previous source has terminated,
+ * building a chain.
+ */
+public class ConcatPublisher<T> implements Publisher<T> {
+ /** Iterator of upstream publishers. */
+ private final Iterator<Publisher<? extends T>> sources;
+
+ /**
+ * Constructor.
+ *
+ * @param sources Iterator of upstream publishers.
+ */
+ public ConcatPublisher(Iterator<Publisher<? extends T>> sources) {
+ this.sources = sources;
+ }
+
+ /** {@inheritDoc} */
+ @Override
+ public void subscribe(Subscriber<? super T> downstream) {
+ ConcatCoordinator<T> subscription = new ConcatCoordinator<>(downstream, sources);
+
+ downstream.onSubscribe(subscription);
+ subscription.drain();
+ }
+
+ /**
+ * Concatenation composite subscription.
+ */
+ static final class ConcatCoordinator<T> extends SubscriptionArbiter implements Subscriber<T> {
+ /** Counter to prevent concurrent execution of a critical section. */
+ private final AtomicInteger guardCntr = new AtomicInteger();
+
+ final Subscriber downstream;
+
+ final Iterator<Publisher<? extends T>> sources;
+
+ long consumed;
+
+ ConcatCoordinator(
+ Subscriber downstream,
+ Iterator<Publisher<? extends T>> sources
+ ) {
+ this.downstream = downstream;
+ this.sources = sources;
+ }
+
+ @Override
+ public void onSubscribe(Subscription s) {
+ setSubscription(s);
+ }
+
+ @Override
+ public void onNext(T item) {
+ consumed++;
+ downstream.onNext(item);
+ }
+
+ @Override
+ public void onError(Throwable throwable) {
+ downstream.onError(throwable);
+ }
+
+ @Override
+ public void onComplete() {
+ drain();
+ }
+
+ void drain() {
+ if (guardCntr.getAndIncrement() == 0) {
+ do {
+ if (isCancelled()) {
+ return;
+ }
+
+ if (!sources.hasNext()) {
+ downstream.onComplete();
+ return;
+ }
+
+ long c = consumed;
+ if (c != 0L) {
+ consumed = 0L;
+ setProduced(c);
+ }
+
+ sources.next().subscribe(this);
+
+ } while ((guardCntr.getAndDecrement() - 1) != 0);
+ }
+ }
+ }
+
+ static class SubscriptionArbiter implements Subscription {
+ Subscription current;
+ static final VarHandle CURRENT;
+
+ Subscription next;
+ static final VarHandle NEXT;
+
+ long requested;
+
+ long downstreamRequested;
+ static final VarHandle DOWNSTREAM_REQUESTED;
+
+ long produced;
+ static final VarHandle PRODUCED;
Review Comment:
I suggest to replace this with `AtomicLong`
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