zstan commented on a change in pull request #8513: URL: https://github.com/apache/ignite/pull/8513#discussion_r555541716
########## File path: modules/core/src/main/java/org/apache/ignite/internal/processors/cache/persistence/pagemem/SegmentedLruPageList.java ########## @@ -0,0 +1,364 @@ +/* + * 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.processors.cache.persistence.pagemem; + +import org.apache.ignite.configuration.PageReplacementMode; +import org.apache.ignite.internal.util.GridUnsafe; + +/** + * Pages Segmented-LRU (SLRU) list implementation. + * + * @see PageReplacementMode#SEGMENTED_LRU + */ +public class SegmentedLruPageList { + /** Ratio to limit count of protected pages. */ + private static final double PROTECTED_TO_TOTAL_PAGES_RATIO = 0.5; + + /** Null page index. */ + static final int NULL_IDX = -1; + + /** Index of the head page of LRU list. */ + private int headIdx = NULL_IDX; + + /** Index of the tail page of LRU list. */ + private int tailIdx = NULL_IDX; + + /** Index of the tail page of probationary segment. */ + private int probTailIdx = NULL_IDX; + + /** Count of protected pages in the list. */ + private int protectedPagesCnt; + + /** Protected pages segment limit. */ + private final int protectedPagesLimit; + + /** Pointer to memory region to store links. */ + private final long linksPtr; + + /** Pointer to memory region to store protected flags. */ + private final long flagsPtr; + + /** + * @param totalPagesCnt Total pages count. + * @param memPtr Pointer to memory region. + */ + public SegmentedLruPageList(int totalPagesCnt, long memPtr) { + linksPtr = memPtr; + flagsPtr = memPtr + (((long)totalPagesCnt) << 3); + + GridUnsafe.setMemory(linksPtr, ((long)totalPagesCnt) << 3, (byte)0xFF); + GridUnsafe.setMemory(flagsPtr, (totalPagesCnt + 7) >> 3, (byte)0); + + protectedPagesLimit = (int)(totalPagesCnt * PROTECTED_TO_TOTAL_PAGES_RATIO); + } + + /** + * Remove page from the head of LRU list. + * + * @return Page index or {@code -1} if list is empty. + */ + public synchronized int poll() { + int idx = headIdx; + + if (idx != NULL_IDX) + remove(idx); + + return idx; + } + + /** + * Remove page from LRU list by page index. + * + * @param pageIdx Page index. + */ + public synchronized void remove(int pageIdx) { Review comment: this methoad are always calling under wlock as i see, thus no need in sync here, only wlock hold check or simple comment, i hope. ########## File path: modules/core/src/main/java/org/apache/ignite/internal/processors/cache/persistence/pagemem/SegmentedLruPageList.java ########## @@ -0,0 +1,364 @@ +/* + * 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.processors.cache.persistence.pagemem; + +import org.apache.ignite.configuration.PageReplacementMode; +import org.apache.ignite.internal.util.GridUnsafe; + +/** + * Pages Segmented-LRU (SLRU) list implementation. + * + * @see PageReplacementMode#SEGMENTED_LRU + */ +public class SegmentedLruPageList { + /** Ratio to limit count of protected pages. */ + private static final double PROTECTED_TO_TOTAL_PAGES_RATIO = 0.5; + + /** Null page index. */ + static final int NULL_IDX = -1; + + /** Index of the head page of LRU list. */ + private int headIdx = NULL_IDX; + + /** Index of the tail page of LRU list. */ + private int tailIdx = NULL_IDX; + + /** Index of the tail page of probationary segment. */ + private int probTailIdx = NULL_IDX; + + /** Count of protected pages in the list. */ + private int protectedPagesCnt; + + /** Protected pages segment limit. */ + private final int protectedPagesLimit; + + /** Pointer to memory region to store links. */ + private final long linksPtr; + + /** Pointer to memory region to store protected flags. */ + private final long flagsPtr; + + /** + * @param totalPagesCnt Total pages count. + * @param memPtr Pointer to memory region. + */ + public SegmentedLruPageList(int totalPagesCnt, long memPtr) { + linksPtr = memPtr; + flagsPtr = memPtr + (((long)totalPagesCnt) << 3); + + GridUnsafe.setMemory(linksPtr, ((long)totalPagesCnt) << 3, (byte)0xFF); + GridUnsafe.setMemory(flagsPtr, (totalPagesCnt + 7) >> 3, (byte)0); + + protectedPagesLimit = (int)(totalPagesCnt * PROTECTED_TO_TOTAL_PAGES_RATIO); + } + + /** + * Remove page from the head of LRU list. + * + * @return Page index or {@code -1} if list is empty. + */ + public synchronized int poll() { + int idx = headIdx; + + if (idx != NULL_IDX) + remove(idx); + + return idx; + } + + /** + * Remove page from LRU list by page index. + * + * @param pageIdx Page index. + */ + public synchronized void remove(int pageIdx) { Review comment: this method are always calling under wlock as i see, thus no need in sync here, only wlock hold check or simple comment, i hope. ---------------------------------------------------------------- This is an automated message from the Apache Git Service. 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