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IGNITE-23597 Cache latest term values in log manager (#5005)
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modules/raft/src/main/java/org/apache/ignite/internal/raft/storage/TermCache.java
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| /* | ||
| * 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. | ||
| */ | ||
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| package org.apache.ignite.internal.raft.storage; | ||
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| import static org.apache.ignite.internal.util.IgniteUtils.isPow2; | ||
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| import org.apache.ignite.raft.jraft.entity.LogId; | ||
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| /** | ||
| * Cyclic buffer to cache several last term values for log storage. | ||
| */ | ||
| public class TermCache { | ||
| private final int mask; | ||
| private final long[] indexes; | ||
| private final long[] terms; | ||
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| // Head position. -1 means the cache is empty. | ||
| private int head = -1; | ||
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| // Tail position. Might be equal to head if the cache only has a single term. | ||
| private int tail; | ||
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| /** | ||
| * Constructor. | ||
| * | ||
| * @param capacity Cache capacity. Must be a power of 2. Should be a small value, term update is a rare operation. | ||
| */ | ||
| public TermCache(int capacity) { | ||
| assert isPow2(capacity) : "Capacity must be a power of 2"; | ||
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| this.mask = capacity - 1; | ||
| this.indexes = new long[capacity]; | ||
| this.terms = new long[capacity]; | ||
| } | ||
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| /** | ||
| * Should be called when appending a new log entry. | ||
| */ | ||
| public void append(LogId id) { | ||
| if (isEmpty()) { | ||
| head = 0; | ||
| indexes[tail] = id.getIndex(); | ||
| terms[tail] = id.getTerm(); | ||
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| return; | ||
| } | ||
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| // Term has not changed, nothing to update. | ||
| if (terms[tail] == id.getTerm()) { | ||
| return; | ||
| } | ||
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| tail = next(tail); | ||
| indexes[tail] = id.getIndex(); | ||
| terms[tail] = id.getTerm(); | ||
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| // Handle buffer overflow by moving head to the next position. | ||
| if (tail == head) { | ||
| head = next(head); | ||
| } | ||
| } | ||
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| private int prev(int i) { | ||
| return (i - 1) & mask; | ||
| } | ||
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| private int next(int i) { | ||
| return (i + 1) & mask; | ||
| } | ||
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| private boolean isEmpty() { | ||
| return head == -1; | ||
| } | ||
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| private int findIndex(long idx) { | ||
| // Could be replaced with a binary search, but why bother for such a small cache. | ||
| for (int i = tail; i != head; i = prev(i)) { | ||
| if (idx >= indexes[i]) { | ||
| return i; | ||
| } | ||
| } | ||
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| return head; | ||
| } | ||
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| /** | ||
| * Lookup term for the given index. Returns {@code -1} if the index is not found in the cache. | ||
| */ | ||
| public long lookup(long idx) { | ||
| if (isEmpty() || idx < indexes[head]) { | ||
| return -1; | ||
| } | ||
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| return terms[findIndex(idx)]; | ||
| } | ||
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| /** | ||
| * Resets the cache to the initial state. | ||
| */ | ||
| public void reset() { | ||
| head = -1; | ||
| tail = 0; | ||
| } | ||
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| /** | ||
| * Truncates the cache to the given index, deleting all information for indexes greater than or equal to the given one. | ||
| */ | ||
| public void truncateTail(long idx) { | ||
| if (isEmpty() || idx < indexes[head]) { | ||
| reset(); | ||
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| return; | ||
| } | ||
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| tail = findIndex(idx); | ||
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| if (indexes[tail] == idx) { | ||
| if (head == tail) { | ||
| reset(); | ||
| } else { | ||
| tail = prev(tail); | ||
| } | ||
| } | ||
| } | ||
| } |
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90
modules/raft/src/test/java/org/apache/ignite/internal/raft/storage/TermCacheTest.java
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| Original file line number | Diff line number | Diff line change |
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| @@ -0,0 +1,90 @@ | ||
| /* | ||
| * 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. | ||
| */ | ||
|
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| package org.apache.ignite.internal.raft.storage; | ||
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| import static org.junit.jupiter.api.Assertions.assertEquals; | ||
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| import org.apache.ignite.raft.jraft.entity.LogId; | ||
| import org.junit.jupiter.api.BeforeEach; | ||
| import org.junit.jupiter.api.Test; | ||
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| class TermCacheTest { | ||
| private TermCache termCache; | ||
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| @BeforeEach | ||
| void setUp() { | ||
| termCache = new TermCache(4); | ||
| } | ||
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| @Test | ||
| void testAppendAndLookup() { | ||
| termCache.append(new LogId(1, 1)); | ||
| termCache.append(new LogId(2, 2)); | ||
| termCache.append(new LogId(3, 3)); | ||
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| assertEquals(-1, termCache.lookup(0)); | ||
| assertEquals(1, termCache.lookup(1)); | ||
| assertEquals(2, termCache.lookup(2)); | ||
| assertEquals(3, termCache.lookup(3)); | ||
| assertEquals(3, termCache.lookup(4)); | ||
| } | ||
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| @Test | ||
| void testAppendSameTerm() { | ||
| termCache.append(new LogId(1, 1)); | ||
| termCache.append(new LogId(2, 1)); | ||
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| assertEquals(1, termCache.lookup(1)); | ||
| assertEquals(1, termCache.lookup(2)); | ||
| } | ||
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| @Test | ||
| void testReset() { | ||
| termCache.append(new LogId(1, 1)); | ||
| termCache.reset(); | ||
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| assertEquals(-1, termCache.lookup(1)); | ||
| } | ||
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| @Test | ||
| void testTruncateTail() { | ||
| termCache.append(new LogId(1, 1)); | ||
| termCache.append(new LogId(2, 1)); | ||
| termCache.append(new LogId(3, 2)); | ||
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| termCache.truncateTail(2); | ||
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| assertEquals(1, termCache.lookup(1)); | ||
| assertEquals(1, termCache.lookup(2)); | ||
| assertEquals(1, termCache.lookup(3)); | ||
| } | ||
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| @Test | ||
| void testTruncateTailExactMatch() { | ||
| termCache.append(new LogId(1, 1)); | ||
| termCache.append(new LogId(2, 2)); | ||
| termCache.append(new LogId(3, 2)); | ||
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| termCache.truncateTail(2); | ||
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| assertEquals(1, termCache.lookup(1)); | ||
| assertEquals(1, termCache.lookup(2)); | ||
| assertEquals(1, termCache.lookup(3)); | ||
| } | ||
| } |