jetbrains.exodus.log.SharedLogCache.kt Maven / Gradle / Ivy

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/**
 * Copyright 2010 - 2022 JetBrains s.r.o.
 *
 * Licensed 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
 *
 * https://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 jetbrains.exodus.log

import jetbrains.exodus.ArrayByteIterable
import jetbrains.exodus.core.dataStructures.*
import jetbrains.exodus.core.dataStructures.ObjectCacheBase.DEFAULT_SIZE
import kotlin.math.min

internal class SharedLogCache : LogCache {

    private val pagesCache: LongObjectCacheBase
    internal val useSoftReferences: Boolean;

    constructor(memoryUsage: Long,
                pageSize: Int,
                nonBlocking: Boolean,
                useSoftReferences: Boolean,
                cacheGenerationCount: Int) : super(memoryUsage, pageSize) {
        this.useSoftReferences = useSoftReferences
        val pagesCount = (memoryUsage / (pageSize +  /* each page consumes additionally 96 bytes in the cache */
                96)).toInt()
        pagesCache = if (nonBlocking) {
            if (useSoftReferences) {
                SoftConcurrentLongObjectCache(pagesCount, cacheGenerationCount)
            } else {
                ConcurrentLongObjectCache(pagesCount, cacheGenerationCount)
            }
        } else {
            if (useSoftReferences) {
                SoftLongObjectCache(pagesCount)
            } else {
                LongObjectCache(pagesCount)
            }
        }
    }

    constructor(memoryUsagePercentage: Int,
                pageSize: Int,
                nonBlocking: Boolean,
                useSoftReferences: Boolean,
                cacheGenerationCount: Int) : super(memoryUsagePercentage, pageSize) {
        this.useSoftReferences = useSoftReferences
        pagesCache = if (memoryUsage == Long.MAX_VALUE) {
            if (nonBlocking) {
                if (useSoftReferences) {
                    SoftConcurrentLongObjectCache(DEFAULT_SIZE, cacheGenerationCount)
                } else {
                    ConcurrentLongObjectCache(DEFAULT_SIZE, cacheGenerationCount)
                }
            } else {
                if (useSoftReferences) {
                    SoftLongObjectCache(DEFAULT_SIZE)
                } else {
                    LongObjectCache()
                }
            }
        } else {
            val pagesCount = (memoryUsage / (pageSize +  /* each page consumes additionally some bytes in the cache */
                    if (useSoftReferences) 160 else 96)).toInt()
            if (nonBlocking) {
                if (useSoftReferences) {
                    SoftConcurrentLongObjectCache(pagesCount, cacheGenerationCount)
                } else {
                    ConcurrentLongObjectCache(pagesCount, cacheGenerationCount)
                }
            } else {
                if (useSoftReferences) {
                    SoftLongObjectCache(pagesCount)
                } else {
                    LongObjectCache(pagesCount)
                }
            }
        }
    }

    override fun clear() { // do nothing on clear since the cache can contain pages of different environments
    }

    override fun hitRate() = pagesCache.hitRate()

    override fun cachePage(log: Log, pageAddress: Long, page: ByteArray) =
            log.identity.let { logIdentity -> cachePage(getLogPageFingerPrint(logIdentity, pageAddress), logIdentity, pageAddress, page) }

    override fun getPage(log: Log, pageAddress: Long): ByteArray {
        val logIdentity = log.identity
        val key = getLogPageFingerPrint(logIdentity, pageAddress)
        val cachedValue = pagesCache.tryKeyLocked(key)
        if (cachedValue != null && cachedValue.logIdentity == logIdentity && cachedValue.address == pageAddress) {
            return cachedValue.page
        }
        var page = log.getHighPage(pageAddress)
        if (page != null) {
            return page
        }
        page = readFullPage(log, pageAddress)
        cachePage(key, logIdentity, pageAddress, page)
        return page
    }

    override fun getCachedPage(log: Log, pageAddress: Long): ByteArray? {
        val logIdentity = log.identity
        val key = getLogPageFingerPrint(logIdentity, pageAddress)
        val cachedValue = pagesCache.getObjectLocked(key)
        return if (cachedValue != null && cachedValue.logIdentity == logIdentity && cachedValue.address == pageAddress) {
            cachedValue.page
        } else log.getHighPage(pageAddress)
    }

    override fun getPageIterable(log: Log, pageAddress: Long): ArrayByteIterable {
        val logIdentity = log.identity
        val key = getLogPageFingerPrint(logIdentity, pageAddress)
        val cachedValue = pagesCache.tryKeyLocked(key)
        if (cachedValue != null && cachedValue.logIdentity == logIdentity && cachedValue.address == pageAddress) {
            return ArrayByteIterable(cachedValue.page)
        }
        var page = log.getHighPage(pageAddress)
        if (page != null) {
            return ArrayByteIterable(page, min(log.highAddress - pageAddress, pageSize.toLong()).toInt())
        }
        page = readFullPage(log, pageAddress)
        cachePage(key, logIdentity, pageAddress, page)
        return ArrayByteIterable(page)
    }

    override fun removePage(log: Log, pageAddress: Long) {
        val key = getLogPageFingerPrint(log.identity, pageAddress)
        pagesCache.removeLocked(key)
    }

    private fun cachePage(key: Long, logIdentity: Int, address: Long, page: ByteArray) {
        pagesCache.cacheObjectLocked(key, CachedValue(logIdentity, address, postProcessTailPage(page)))
    }

    private class CachedValue(val logIdentity: Int, val address: Long, val page: ByteArray)
}

private fun getLogPageFingerPrint(logIdentity: Int, address: Long): Long = (address + logIdentity shl 32) + address + logIdentity