petrov-mg commented on code in PR #12429: URL: https://github.com/apache/ignite/pull/12429#discussion_r2770867465
########## modules/commons/src/main/java/org/apache/ignite/internal/thread/context/Context.java: ########## @@ -0,0 +1,321 @@ +/* + * 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.thread.context; + +import java.util.ArrayList; +import java.util.List; +import org.apache.ignite.internal.util.typedef.F; +import org.jetbrains.annotations.Nullable; + +/** + * Represents a storage of {@link ContextAttribute}s and their corresponding values bound to the thread. + * The state of Context is determined by a sequence of {@link Update}s applied to it. Each Update stores the + * updated or newly added {@link ContextAttribute} values and link to the previous Update. + * <pre> + * +-----------+ +-----------+ + * | | | A1 -> V2 | + * null <--| A1 -> V1 |<--| | + * | | | A2 -> V3 | + * +-----------+ +-----------+ + *</pre> + * Context Updates can be undone in the same order they were applied by closing the {@link Scope} associated with each + * update (see {@link #set(ContextAttribute, Object)} and related methods). + */ +public class Context { + /** */ + private static final ThreadLocal<Context> INSTANCE = ThreadLocal.withInitial(Context::new); + + /** + * Sequence of updated applied to the Context. Each update holds a link to the previous Update, so we store only + * the reference to the last one. + */ + @Nullable private Update lastUpd; + + /** */ + private Context() { + // No-op. + } + + /** + * Retrieves value associated with specified attribute by accessing Context bound to the thread this method is + * called from. If no value is explicitly associated with specified attribute, {@link ContextAttribute#initialValue()} + * is returned. + * + * @param attr Context Attribute. + * @return Context Attribute Value. + */ + @Nullable public static <T> T get(ContextAttribute<T> attr) { + AttributeValueHolder<T> valHolder = INSTANCE.get().attributeValue(attr); + + return valHolder == null ? attr.initialValue() : valHolder.value(); + } + + /** + * Updates the value of the specified attribute for the Context bound to the thread this method is called from. + * + * @param attr Context Attribute. + * @return Scope instance that, when closed, undoes the applied update. It is crucial to undo all applied Context + * updates to free up thread-bound resources and avoid memory leaks, so it is highly encouraged to use a + * try-with-resource block to close the returned Scope. Note, updates must be undone in the same order they were applied. + */ + public static <T> Scope set(ContextAttribute<T> attr, T val) { + if (get(attr) == val) Review Comment: Done. ########## modules/commons/src/main/java/org/apache/ignite/internal/thread/context/Context.java: ########## @@ -0,0 +1,321 @@ +/* + * 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.thread.context; + +import java.util.ArrayList; +import java.util.List; +import org.apache.ignite.internal.util.typedef.F; +import org.jetbrains.annotations.Nullable; + +/** + * Represents a storage of {@link ContextAttribute}s and their corresponding values bound to the thread. + * The state of Context is determined by a sequence of {@link Update}s applied to it. Each Update stores the + * updated or newly added {@link ContextAttribute} values and link to the previous Update. + * <pre> + * +-----------+ +-----------+ + * | | | A1 -> V2 | + * null <--| A1 -> V1 |<--| | + * | | | A2 -> V3 | + * +-----------+ +-----------+ + *</pre> + * Context Updates can be undone in the same order they were applied by closing the {@link Scope} associated with each + * update (see {@link #set(ContextAttribute, Object)} and related methods). + */ +public class Context { + /** */ + private static final ThreadLocal<Context> INSTANCE = ThreadLocal.withInitial(Context::new); + + /** + * Sequence of updated applied to the Context. Each update holds a link to the previous Update, so we store only + * the reference to the last one. + */ + @Nullable private Update lastUpd; + + /** */ + private Context() { + // No-op. + } + + /** + * Retrieves value associated with specified attribute by accessing Context bound to the thread this method is + * called from. If no value is explicitly associated with specified attribute, {@link ContextAttribute#initialValue()} + * is returned. + * + * @param attr Context Attribute. + * @return Context Attribute Value. + */ + @Nullable public static <T> T get(ContextAttribute<T> attr) { + AttributeValueHolder<T> valHolder = INSTANCE.get().attributeValue(attr); + + return valHolder == null ? attr.initialValue() : valHolder.value(); + } + + /** + * Updates the value of the specified attribute for the Context bound to the thread this method is called from. + * + * @param attr Context Attribute. + * @return Scope instance that, when closed, undoes the applied update. It is crucial to undo all applied Context + * updates to free up thread-bound resources and avoid memory leaks, so it is highly encouraged to use a + * try-with-resource block to close the returned Scope. Note, updates must be undone in the same order they were applied. + */ + public static <T> Scope set(ContextAttribute<T> attr, T val) { + if (get(attr) == val) + return Scope.NOOP_SCOPE; + + return INSTANCE.get().applyUpdates(new AttributeValueHolder<>(attr, val)); + } + + /** + * Updates the values of the specified attributes for the Context bound to the thread this method is called from. + * + * @param attr1 First Context Attribute. + * @param val1 Values associated with first Context Attribute. + * @param attr2 Second Context Attribute. + * @param val2 Values associated with second Context Attribute. + * @return Scope instance that, when closed, undoes the applied update. It is crucial to undo all applied Context + * updates to free up thread-bound resources and avoid memory leaks, so it is highly encouraged to use a + * try-with-resource block to close the returned Scope. Note, updates must be undone in the same order they were applied. + */ + public static <T1, T2> Scope set( + ContextAttribute<T1> attr1, T1 val1, + ContextAttribute<T2> attr2, T2 val2 + ) { + return ContextUpdater.create().set(attr1, val1).set(attr2, val2).apply(); + } + + /** + * Updates the values of the specified attributes for the Context bound to the thread this method is called from. + * + * @param attr1 First Context Attribute. + * @param val1 Values associated with first Context Attribute. + * @param attr2 Second Context Attribute. + * @param val2 Values associated with second Context Attribute. + * @param attr3 Third Context Attribute. + * @param val3 Values associated with third Context Attribute. + * @return Scope instance that, when closed, undoes the applied update. It is crucial to undo all applied Context + * updates to free up thread-bound resources and avoid memory leaks, so it is highly encouraged to use a + * try-with-resource block to close the returned Scope. Note, updates must be undone in the same order they were applied. + */ + public static <T1, T2, T3> Scope set( + ContextAttribute<T1> attr1, T1 val1, + ContextAttribute<T2> attr2, T2 val2, + ContextAttribute<T3> attr3, T3 val3 + ) { + return ContextUpdater.create().set(attr1, val1).set(attr2, val2).set(attr3, val3).apply(); + } + + /** + * Creates Snapshot of all attributes and their corresponding values stored in the Context bound to the thread this + * method is called from. + * + * @return Context Snapshot. + */ + public static ContextSnapshot createSnapshot() { + return INSTANCE.get().createSnapshotInternal(); + } + + /** + * Restores values of all attributes for Context bound to the thread this method is called from. + * + * @param snp Context Snapshot. + * @return Scope instance that, when closed, undoes the applied operation. It is crucial to undo all applied Context + * updates to free up thread-bound resources and avoid memory leaks, so it is highly encouraged to use a + * try-with-resource block to close the returned Scope. Note, updates must be undone in the same order they were applied. + */ + public static Scope restoreSnapshot(ContextSnapshot snp) { + return INSTANCE.get().restoreSnapshotInternal(snp); + } + + /** Retrieves value for the specified attribute from the current Context. */ + @Nullable private <T> AttributeValueHolder<T> attributeValue(ContextAttribute<T> attr) { + if (lastUpd == null || (lastUpd.storedAttrBits & attr.bitmask()) == 0) + return null; + + AttributeValueHolder<T> res = findAttributeValue(attr); + + assert res != null; + assert res.attribute().equals(attr); + + return res; + } + + /** Updates the current context with the specified attributes and their corresponding values. */ + private Scope applyUpdates(AttributeValueHolder<?>... atrVals) { + lastUpd = new Update(atrVals, lastUpd); + + return lastUpd; + } + + /** Undoes the latest updated. */ + private void undo(Update upd) { + assert lastUpd == upd; + + lastUpd = lastUpd.prev; + } + + /** Iterates over the currently applied context updates and finds the latest value associated with the specified attribute. */ + private <T> AttributeValueHolder<T> findAttributeValue(ContextAttribute<T> attr) { + for (Update upd = lastUpd; upd != null; upd = upd.prev) { + if (!upd.holdsValueFor(attr)) + continue; + + return upd.value(attr); + } + + return null; + } + + /** */ + private ContextSnapshot createSnapshotInternal() { + // The sequence of updates defines the state of the Context. Each update is linked to the previous one and immutable. + // Therefore, to restore the context state elsewhere, we only need to share a reference to the most recent update. + return lastUpd; + } + + /** */ + private Scope restoreSnapshotInternal(ContextSnapshot newSnp) { + ContextSnapshot prevSnp = createSnapshotInternal(); + + if (newSnp == prevSnp) + return Scope.NOOP_SCOPE; + + changeState(prevSnp, newSnp); + + return () -> INSTANCE.get().changeState(newSnp, prevSnp); + } + + /** */ + private void changeState(ContextSnapshot expState, ContextSnapshot newState) { + assert lastUpd == expState; + + lastUpd = (Update)newState; + } + + /** Represents Update applied to the Context. */ + private static class Update implements Scope, ContextSnapshot { + /** Updated attributes and their corresponding values. */ + private final AttributeValueHolder<?>[] attrVals; + + /** + * Bits representing all attributes which values were changed by this update. + * + * @see ContextAttribute#bitmask() + */ + private final int updAttrBits; + + /** + * Bits representing all attributes stored in the current Context after this Update and all preceding are applied. + * We need this for two purposes: + * <ul> + * <li>fast check whether any of the currently applied Context Updates store value for the particular attribute</li> + * <li>do not recalculate state of all attributes when update is undone</li> + * </ul> + * + * @see ContextAttribute#bitmask() + */ + private final int storedAttrBits; + + /** Link to the previous update. */ + private final Update prev; + + /** */ + Update(AttributeValueHolder<?>[] attrVals, Update prev) { + this.attrVals = attrVals; + this.prev = prev; + + updAttrBits = mergeUpdatedAttributeBits(attrVals); + storedAttrBits = prev == null ? updAttrBits : prev.storedAttrBits | updAttrBits; + } + + /** @return Whether current update contains value for the specified attribute. */ + boolean holdsValueFor(ContextAttribute<?> attr) { + return (updAttrBits & attr.bitmask()) != 0; + } + + /** + * @return Attribute value that was set by the current update for the specified attribute. {@code null} if + * specified Attribute was not changed by this update. + */ + @Nullable <T> AttributeValueHolder<T> value(ContextAttribute<T> attr) { + // We iterate in reverse order to correctly handle the case when the value for the same attribute is + // specified multiple times. + for (int i = attrVals.length - 1; i >= 0; i--) { + AttributeValueHolder<?> valHolder = attrVals[i]; + + if (valHolder.attribute().equals(attr)) + return ((AttributeValueHolder<T>)valHolder); + } + + return null; + } + + /** */ + private static int mergeUpdatedAttributeBits(AttributeValueHolder<?>[] attrVals) { + int res = 0; + + for (AttributeValueHolder<?> attrVal : attrVals) + res |= attrVal.attribute().bitmask(); + + return res; + } + + /** */ + @Override public void close() { + INSTANCE.get().undo(this); + } + } + + /** Allows to change multiple attribute values in a single update operation and skip updates that changes nothing. */ + private static class ContextUpdater { + /** */ + private static final int INIT_UPDATES_CAPACITY = 3; + + /** */ + private List<AttributeValueHolder<?>> updates; + + /** */ + <T> ContextUpdater set(ContextAttribute<T> attr, T val) { + if (get(attr) == val) Review Comment: Done. -- This is an automated message from the Apache Git Service. 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