HBase \u63d0\u4f9b\u4e86\u4e24\u79cd\u4e3b\u8981\u7684 BlockCache \u5b9e\u73b0：<\/p>\n
\u5728\u73b0\u4ee3 HBase \u7248\u672c（2.0+）\u4e2d，\u5f53\u542f\u7528\u00a0BucketCache\u00a0\u65f6，\u901a\u5e38\u4f1a\u91c7\u7528\u4e00\u79cd\u540d\u4e3a\u00a0CombinedBlockCache\u00a0\u7684\u7ec4\u5408\u6a21\u5f0f：<\/p>\n
\u4ece\u6587\u6863\u7247\u6bb5\u4e2d\u4e5f\u80fd\u5370\u8bc1\u8fd9\u4e00\u70b9：<\/p>\n
src\/main\/asciidoc\/_chapters\/architecture.adoc:973-998\u00a0<\/p>\n
…when BucketCache is enabled, all DATA blocks are kept in the BucketCache tier and meta blocks — INDEX and BLOOM blocks — are on-heap in the\u00a0LruBlockCache.<\/p>\n
LruBlockCache\u00a0\u6ca1\u6709\u4f7f\u7528 \u5e38\u89c1\u7684\u201c\u54c8\u5e0c\u8868 + \u53cc\u5411\u94fe\u8868\u201d\u6765\u5b9e\u73b0 LRU\u3002\u8fd9\u80cc\u540e\u5176\u5b9e\u662f HBase \u9488\u5bf9\u5176\u7279\u5b9a\u573a\u666f\u505a\u51fa\u7684\u6027\u80fd\u6743\u8861\u548c\u8bbe\u8ba1\u9009\u62e9\u3002<\/p>\n
\u7b80\u5355\u6765\u8bf4，\u539f\u56e0\u4e3b\u8981\u6709\u4ee5\u4e0b\u51e0\u70b9：<\/p>\n
\u4ece\u00a0evict()\u00a0\u65b9\u6cd5\u7684\u5b9e\u73b0\u4e2d\u6211\u4eec\u53ef\u4ee5\u770b\u5230，HBase \u7684\u00a0LruBlockCache\u00a0\u5e76\u4e0d\u662f\u4e00\u4e2a\u5355\u4e00\u7684 LRU \u961f\u5217\u3002\u5b83\u5c06\u7f13\u5b58\u7684 Block \u5206\u4e3a\u4e09\u4e2a\u4e0d\u540c\u7684\u4f18\u5148\u7ea7\u6876（Bucket）：<\/p>\n
\/\/ … existing code …
\n \/\/ Instantiate priority buckets
\n BlockBucket bucketSingle = new BlockBucket("single", bytesToFree, blockSize, singleSize());
\n BlockBucket bucketMulti = new BlockBucket("multi", bytesToFree, blockSize, multiSize());
\n BlockBucket bucketMemory = new BlockBucket("memory", bytesToFree, blockSize, memorySize());<\/p>\n
\/\/ Scan entire map putting into appropriate buckets
\n for (LruCachedBlock cachedBlock : map.values()) {
\n switch (cachedBlock.getPriority()) {
\n case SINGLE: {
\n bucketSingle.add(cachedBlock);
\n break;
\n }
\n case MULTI: {
\n bucketMulti.add(cachedBlock);
\n break;
\n }
\n case MEMORY: {
\n bucketMemory.add(cachedBlock);
\n break;
\n }
\n }
\n }
\n\/\/ … existing code …<\/p>\n
\u9a71\u9010\u6570\u636e\u65f6，\u5b83\u7684\u903b\u8f91\u4e5f\u6bd4\u7b80\u5355\u7684\u201c\u6dd8\u6c70\u6700\u4e45\u672a\u4f7f\u7528\u7684\u201d\u590d\u6742\u5f97\u591a\u3002\u5b83\u4f1a\u6839\u636e\u6bcf\u4e2a\u6876\u7684\u914d\u7f6e\u5927\u5c0f（singleFactor,\u00a0multiFactor,\u00a0memoryFactor）\u548c\u5f53\u524d\u5b9e\u9645\u5927\u5c0f\u8ba1\u7b97\u51fa\u201c\u6ea2\u51fa\u201d\u91cf，\u7136\u540e\u6309\u6bd4\u4f8b\u4ece\u4e0d\u540c\u7684\u6876\u4e2d\u6dd8\u6c70\u6570\u636e\u3002<\/p>\n
\u5982\u679c\u4f7f\u7528\u53cc\u5411\u94fe\u8868，\u5c31\u9700\u8981\u7ef4\u62a4\u4e09\u4e2a\u72ec\u7acb\u7684\u94fe\u8868，\u5e76\u4e14\u5728 Block \u7684\u4f18\u5148\u7ea7\u53d1\u751f\u53d8\u5316\u65f6（\u4f8b\u5982，\u4e00\u4e2a\u00a0SINGLE\u00a0\u8bbf\u95ee\u7684 Block \u88ab\u518d\u6b21\u8bbf\u95ee，\u9700\u8981\u5347\u7ea7\u5230\u00a0MULTI），\u9700\u8981\u5728\u4e0d\u540c\u94fe\u8868\u4e4b\u95f4\u79fb\u52a8\u8282\u70b9，\u8fd9\u4f1a\u589e\u52a0\u5e76\u53d1\u63a7\u5236\u7684\u590d\u6742\u6027\u3002<\/p>\n
HBase \u662f\u4e00\u4e2a\u9ad8\u5e76\u53d1\u7684\u5206\u5e03\u5f0f\u6570\u636e\u5e93，\u5b83\u7684 BlockCache \u4f1a\u88ab\u5927\u91cf\u7684\u8bfb\u5199\u7ebf\u7a0b\u540c\u65f6\u8bbf\u95ee\u3002\u8bbe\u8ba1\u4e0a\u5fc5\u987b\u4f18\u5148\u4fdd\u8bc1\u00a0getBlock()（\u8bfb\u7f13\u5b58）\u548c\u00a0cacheBlock()（\u5199\u7f13\u5b58）\u7684\u6027\u80fd\u3002<\/p>\n
\u8bfb\u64cd\u4f5c (getBlock)：\u5728\u00a0LruBlockCache\u00a0\u4e2d，\u4e00\u6b21\u7f13\u5b58\u547d\u4e2d（hit）\u7684\u64cd\u4f5c\u975e\u5e38\u5feb\u3002\u5b83\u901a\u8fc7\u00a0ConcurrentHashMap.computeIfPresent\u00a0\u6765\u5b9e\u73b0，\u8fd9\u5728\u5f88\u5927\u7a0b\u5ea6\u4e0a\u662f\u65e0\u9501\u7684\u3002\u547d\u4e2d\u540e，\u4ec5\u4ec5\u662f\u8c03\u7528\u00a0cb.access()\u00a0\u66f4\u65b0\u4e00\u4e0b\u8bbf\u95ee\u65f6\u95f4\u548c\u8ba1\u6570\u5668，\u8fd9\u4e2a\u64cd\u4f5c\u4e5f\u662f\u8f7b\u91cf\u7ea7\u7684，\u4e0d\u6d89\u53ca\u590d\u6742\u7684\u6570\u636e\u7ed3\u6784\u4fee\u6539（\u5982\u94fe\u8868\u6307\u9488\u7684\u79fb\u52a8）\u3002<\/p>\n<\/li>\n
\u5199\u64cd\u4f5c (cacheBlock)：\u4e3b\u8981\u662f\u5411\u00a0ConcurrentHashMap\u00a0\u4e2d\u00a0put\u00a0\u4e00\u4e2a\u5143\u7d20\u3002<\/p>\n<\/li>\n<\/ul>\n
\u5982\u679c\u4f7f\u7528\u4f20\u7edf\u7684\u54c8\u5e0c\u53cc\u5411\u94fe\u8868，\u6bcf\u6b21\u8bbf\u95ee（getBlock）\u90fd\u9700\u8981\u79fb\u52a8\u8282\u70b9\u5230\u94fe\u8868\u5934\u90e8，\u8fd9\u4e2a\u64cd\u4f5c\u9700\u8981\u5bf9\u94fe\u8868\u8fdb\u884c\u5199\u64cd\u4f5c，\u5fc5\u987b\u52a0\u9501\u6765\u4fdd\u8bc1\u7ebf\u7a0b\u5b89\u5168，\u8fd9\u5728\u9ad8\u5e76\u53d1\u573a\u666f\u4e0b\u4f1a\u6210\u4e3a\u4e25\u91cd\u7684\u6027\u80fd\u74f6\u9888\u3002<\/p>\n
LruBlockCache\u00a0\u7684\u8bbe\u8ba1\u505a\u4e86\u4e00\u4e2a\u975e\u5e38\u660e\u786e\u7684\u53d6\u820d：\u5c06\u590d\u6742\u6027\u548c\u6027\u80fd\u5f00\u9500\u4ece\u9ad8\u9891\u7684\u8bfb\u64cd\u4f5c\u8f6c\u79fb\u5230\u4e86\u76f8\u5bf9\u4f4e\u9891\u7684\u9a71\u9010\u64cd\u4f5c\u4e0a\u3002<\/p>\n
evict()\u00a0\u65b9\u6cd5\u5728\u6267\u884c\u65f6\u4f1a\u83b7\u53d6\u4e00\u4e2a\u5168\u5c40\u7684\u00a0evictionLock，\u6b64\u65f6\u6574\u4e2a\u9a71\u9010\u8fc7\u7a0b\u662f\u4e32\u884c\u6267\u884c\u7684\u3002\u901a\u8fc7\u904d\u5386\u00a0map\u00a0\u7684\u6240\u6709\u00a0values()\u00a0\u6765\u5b9e\u65f6\u6784\u5efa\u5404\u4e2a\u9a71\u9010\u6876\u548c\u4f18\u5148\u7ea7\u961f\u5217，\u867d\u7136\u8fd9\u4e2a\u64cd\u4f5c\u662f O(N) \u7684，\u4f46\u5b83\u907f\u514d\u4e86\u5728\u6bcf\u6b21\u8bfb\u7f13\u5b58\u65f6\u90fd\u8fdb\u884c\u52a0\u9501\u7684\u94fe\u8868\u64cd\u4f5c\u3002\u5bf9\u4e8e\u4e00\u4e2a\u8bbe\u8ba1\u826f\u597d\u3001\u547d\u4e2d\u7387\u9ad8\u7684\u7f13\u5b58\u6765\u8bf4，\u8fd9\u79cd\u201c\u8bfb\u5feb，\u9a71\u9010\u6162\u201d\u7684\u8bbe\u8ba1\u662f\u5b8c\u5168\u503c\u5f97\u7684\u3002<\/p>\n
LruBlockCache\u00a0\u4e0d\u4f7f\u7528\u54c8\u5e0c\u53cc\u5411\u94fe\u8868，\u662f\u56e0\u4e3a：<\/p>\n
\u8fd9\u79cd\u8bbe\u8ba1\u662f\u5178\u578b\u7684\u5728\u7279\u5b9a\u4e1a\u52a1\u573a\u666f\u4e0b\u5bf9\u901a\u7528\u6570\u636e\u7ed3\u6784\u8fdb\u884c\u6743\u8861\u548c\u4f18\u5316\u7684\u8303\u4f8b\u3002<\/p>\n<\/p>\n
Caffeine\u00a0 \u901a\u8fc7\u591a\u4e2a\u961f\u5217\u548c\u590d\u6742\u7684\u7b97\u6cd5（W-TinyLFU）\u5728\u7ef4\u6301 O(1) \u590d\u6742\u5ea6\u7684\u540c\u65f6，\u5b9e\u73b0\u4e86\u6bd4\u4f20\u7edf LRU \u66f4\u9ad8\u7684\u547d\u4e2d\u7387\u3002<\/p>\n
\u90a3\u4e48，\u4e3a\u4ec0\u4e48 HBase \u7684\u00a0LruBlockCache\u00a0\u6ca1\u6709\u91c7\u7528\u7c7b\u4f3c Caffeine \u7684\u201c\u591a\u961f\u5217（\u53cc\u5411\u94fe\u8868）\u201d\u8bbe\u8ba1，\u800c\u662f\u9009\u62e9\u4e86\u201c\u9a71\u9010\u65f6\u904d\u5386\u5efa\u5806\u201d\u8fd9\u79cd\u770b\u8d77\u6765\u66f4\u201c\u7b28\u91cd\u201d\u7684\u65b9\u5f0f\u5462？<\/p>\n
Caffeine \u901a\u8fc7\u591a\u6307\u9488\u6784\u5efa\u4e86\u4e00\u4e2a\u56fe，\u91cd\u590d\u5229\u7528\u4e86\u8282\u70b9<\/p>\n
\u8fd9\u4e3b\u8981\u662f\u7531\u5386\u53f2\u539f\u56e0\u3001\u8bbe\u8ba1\u6f14\u8fdb\u548c\u7279\u5b9a\u573a\u666f\u4e0b\u7684\u6027\u80fd\u6743\u8861\u5171\u540c\u51b3\u5b9a\u7684\u3002<\/p>\n
LruBlockCache\u00a0\u662f HBase \u4e2d\u4e00\u4e2a\u76f8\u5f53\u201c\u5143\u8001\u201d\u7ea7\u522b\u7684\u7ec4\u4ef6\u3002\u5728\u5b83\u88ab\u8bbe\u8ba1\u548c\u5b9e\u73b0\u7684\u5e74\u4ee3（\u8fdc\u65e9\u4e8e Caffeine \u7684\u51fa\u73b0），\u9762\u4e34\u7684\u4e3b\u8981\u75db\u70b9\u662f\u5982\u4f55\u5728\u9ad8\u5e76\u53d1\u4e0b\u51cf\u5c11\u9501\u7ade\u4e89\u3002<\/p>\n
Caffeine \u662f\u4e00\u4e2a\u901a\u7528\u7684\u3001\u9876\u7ea7\u7684\u672c\u5730\u7f13\u5b58\u5e93，\u5b83\u7684 W-TinyLFU \u7b97\u6cd5\u975e\u5e38\u590d\u6742，\u9700\u8981\u7cbe\u786e\u5730\u7ba1\u7406\u591a\u4e2a\u961f\u5217\u3001\u9891\u7387\u8349\u56fe（Frequency Sketch）\u7b49，\u4ee5\u8fbe\u5230\u8fd1\u4f3c\u6700\u4f18\u7684\u7f13\u5b58\u6548\u679c\u3002<\/p>\n
\u800c\u00a0LruBlockCache\u00a0\u7684\u76ee\u6807\u5219\u66f4\u4e13\u4e00：\u4e3a HFile \u7684 Block \u670d\u52a1\u3002\u5b83\u7684\u4e09\u7ea7\u4f18\u5148\u7ea7\u8bbe\u8ba1（SINGLE,\u00a0MULTI,\u00a0MEMORY）\u662f\u4e3a HBase \u7684\u7279\u5b9a\u5de5\u4f5c\u8d1f\u8f7d\u91cf\u8eab\u5b9a\u505a\u7684：<\/p>\n
\u8fd9\u79cd\u7b80\u5355\u7684\u4e09\u7ea7\u5206\u7c7b\u867d\u7136\u4e0d\u5982 Caffeine \u7cbe\u7ec6，\u4f46\u5bf9\u4e8e HBase \u7684\u573a\u666f\u6765\u8bf4，\u8db3\u591f\u6709\u6548\u4e14\u5b9e\u73b0\u7b80\u5355\u3001\u903b\u8f91\u6e05\u6670\u3001\u6613\u4e8e\u8c03\u8bd5\u3002<\/p>\n
HBase \u540e\u6765\u5f15\u5165\u4e86\u57fa\u4e8e Caffeine \u7684\u7f13\u5b58\u5b9e\u73b0！<\/p>\n
\u4e3a\u4e86\u63d0\u4f9b\u66f4\u4f18\u7684\u7f13\u5b58\u6027\u80fd，HBase \u793e\u533a\u5f00\u53d1\u4e86\u00a0TinyLfuBlockCache\u3002\u8fd9\u4e2a\u7c7b\u5176\u5b9e\u5c31\u662f\u5bf9 Caffeine Cache \u7684\u4e00\u4e2a\u5c01\u88c5\u548c\u9002\u914d，\u4f7f\u5176\u80fd\u591f\u65e0\u7f1d\u5730\u5728 HBase \u4e2d\u4f7f\u7528\u3002<\/p>\n
\u53ef\u4ee5\u5728 HBase \u7684\u914d\u7f6e\u4e2d，\u901a\u8fc7\u00a0hfile.block.cache.policy\u00a0\u6765\u9009\u62e9\u4f7f\u7528\u54ea\u79cd\u7f13\u5b58\u7b56\u7565\u3002<\/p>\n
hbase-default.xml<\/p>\n
<property>
\n <name>hfile.block.cache.policy<\/name>
\n <value>LRU<\/value> <!– \u9ed8\u8ba4\u662f LruBlockCache –>
\n <!– \u4f60\u53ef\u4ee5\u5c06\u5176\u4fee\u6539\u4e3a TinyLFU \u6765\u542f\u7528\u57fa\u4e8e Caffeine \u7684\u7f13\u5b58 –>
\n <!– <value>TinyLFU<\/value> –>
\n<\/property><\/p>\n
\u4e4b\u6240\u4ee5\u4e0d\u76f4\u63a5\u7528\u00a0TinyLfuBlockCache\u00a0(Caffeine) \u66ff\u6362\u6389\u00a0LruBlockCache，\u800c\u662f\u4f5c\u4e3a\u4e00\u79cd\u53ef\u9009\u9879，\u4e3b\u8981\u6709\u4ee5\u4e0b\u8003\u8651：<\/p>\n
\u53ef\u4ee5\u8fd9\u6837\u7406\u89e3：<\/p>\n
\u6240\u4ee5，HBase \u5e76\u975e\u6ca1\u6709\u770b\u5230\u66f4\u4f18\u7684\u65b9\u6848，\u800c\u662f\u901a\u8fc7\u201c\u63d2\u4ef6\u5316\u201d\u7684\u65b9\u5f0f，\u5728\u4fdd\u8bc1\u7cfb\u7edf\u7a33\u5b9a\u6027\u7684\u524d\u63d0\u4e0b，\u4f18\u96c5\u5730\u96c6\u6210\u4e86\u66f4\u73b0\u4ee3\u3001\u66f4\u9ad8\u6548\u7684\u8bbe\u8ba1\u3002<\/p>\n<\/p>\n
LruCachedBlock\u00a0\u662f Apache HBase \u4e2d LRU (Least Recently Used, \u6700\u8fd1\u6700\u5c11\u4f7f\u7528) \u7f13\u5b58\u7b56\u7565\u7684\u6838\u5fc3\u5b9e\u73b0\u4e4b\u4e00\u3002\u5b83\u4ee3\u8868\u4e86\u00a0LruBlockCache\u00a0\u4e2d\u7684\u4e00\u4e2a\u7f13\u5b58\u6761\u76ee\u3002\u6211\u4eec\u53ef\u4ee5\u4ece\u5b83\u7684\u5b9a\u4e49\u3001\u6210\u5458\u53d8\u91cf\u3001\u6784\u9020\u51fd\u6570\u548c\u5173\u952e\u65b9\u6cd5\u7b49\u65b9\u9762\u6765\u6df1\u5165\u7406\u89e3\u5176\u8bbe\u8ba1\u548c\u4f5c\u7528\u3002<\/p>\n
@InterfaceAudience.Private
\npublic class LruCachedBlock implements HeapSize, Comparable<LruCachedBlock> {
\n\/\/…
\n}<\/p>\n
\/\/ … existing code …
\npublic interface HeapSize {
\n \/**
\n * Return the approximate 'exclusive deep size' of implementing object. Includes count of payload
\n * and hosting object sizings.
\n *\/
\n long heapSize();
\n}<\/p>\n<\/li>\n
LruCachedBlock\u00a0\u5c01\u88c5\u4e86\u4f5c\u4e3a\u4e00\u4e2a\u7f13\u5b58\u6761\u76ee\u6240\u9700\u7684\u6240\u6709\u4fe1\u606f\u3002<\/p>\n
\/\/ … existing code …
\n public final static long PER_BLOCK_OVERHEAD =
\n ClassSize.align(ClassSize.OBJECT + (3 * ClassSize.REFERENCE) + (3 * Bytes.SIZEOF_LONG)
\n + ClassSize.STRING + ClassSize.BYTE_BUFFER);<\/p>\n
private final BlockCacheKey cacheKey;
\n private final Cacheable buf;
\n private volatile long accessTime;
\n private long size;
\n private BlockPriority priority;
\n \/**
\n * Time this block was cached. Presumes we are created just before we are added to the cache.
\n *\/
\n private final long cachedTime = System.nanoTime();
\n\/\/ … existing code …<\/p>\n
\/\/ … existing code …
\n public LruCachedBlock(BlockCacheKey cacheKey, Cacheable buf, long accessTime) {
\n this(cacheKey, buf, accessTime, false);
\n }<\/p>\n
public LruCachedBlock(BlockCacheKey cacheKey, Cacheable buf, long accessTime, boolean inMemory) {
\n this.cacheKey = cacheKey;
\n this.buf = buf;
\n this.accessTime = accessTime;
\n \/\/ We approximate the size of this class by the size of its name string
\n \/\/ plus the size of its byte buffer plus the overhead associated with all
\n \/\/ the base classes. We also include the base class
\n \/\/ sizes in the PER_BLOCK_OVERHEAD variable rather than align()ing them with
\n \/\/ their buffer lengths. This variable is used elsewhere in unit tests.
\n this.size =
\n ClassSize.align(cacheKey.heapSize()) + ClassSize.align(buf.heapSize()) + PER_BLOCK_OVERHEAD;
\n if (inMemory) {
\n this.priority = BlockPriority.MEMORY;
\n } else {
\n this.priority = BlockPriority.SINGLE;
\n }
\n }
\n\/\/ … existing code …<\/p>\n
\u6784\u9020\u51fd\u6570\u5b8c\u6210\u4e86\u6240\u6709\u5b57\u6bb5\u7684\u521d\u59cb\u5316\u3002<\/p>\n
\u8fd9\u4e9b\u65b9\u6cd5\u5b9a\u4e49\u4e86\u00a0LruCachedBlock\u00a0\u7684\u884c\u4e3a，\u662f LRU \u7f13\u5b58\u903b\u8f91\u80fd\u591f\u6b63\u786e\u8fd0\u884c\u7684\u4fdd\u8bc1\u3002<\/p>\n
access(long accessTime): \u5f53\u7f13\u5b58\u5757\u88ab\u547d\u4e2d\u65f6\u8c03\u7528\u3002<\/p>\n
\/\/ … existing code …
\n public void access(long accessTime) {
\n this.accessTime = accessTime;
\n if (this.priority == BlockPriority.SINGLE) {
\n this.priority = BlockPriority.MULTI;
\n }
\n }
\n\/\/ … existing code …<\/p>\n
\u5b83\u4f1a\u66f4\u65b0\u00a0accessTime\u00a0\u4e3a\u6700\u65b0\u7684\u8bbf\u95ee\u5e8f\u5217\u53f7，\u5e76\u68c0\u67e5\u5f53\u524d\u4f18\u5148\u7ea7\u3002\u5982\u679c\u4f18\u5148\u7ea7\u662f\u00a0SINGLE，\u5c31\u5c06\u5176\u63d0\u5347\u4e3a\u00a0MULTI\u3002\u8fd9\u4e2a\u673a\u5236\u662f LRU \u7f13\u5b58\u7684\u91cd\u8981\u4f18\u5316\u3002<\/p>\n<\/li>\n
heapSize(): \u5b9e\u73b0\u4e86\u00a0HeapSize\u00a0\u63a5\u53e3\u3002<\/p>\n
\/\/ … existing code …
\n @Override
\n public long heapSize() {
\n return size;
\n }
\n\/\/ … existing code …<\/p>\n
\u76f4\u63a5\u8fd4\u56de\u5728\u6784\u9020\u51fd\u6570\u4e2d\u8ba1\u7b97\u597d\u7684\u00a0size\u00a0\u5b57\u6bb5\u3002<\/p>\n<\/li>\n
compareTo(LruCachedBlock that): \u5b9e\u73b0\u4e86\u00a0Comparable\u00a0\u63a5\u53e3，\u5b9a\u4e49\u4e86\u6392\u5e8f\u89c4\u5219\u3002<\/p>\n
\/\/ … existing code …
\n @Override
\n public int compareTo(LruCachedBlock that) {
\n \/\/ Newer accessed blocks sort before older ones.
\n if (this.accessTime == that.accessTime) return 0;
\n return this.accessTime < that.accessTime ? 1 : -1;
\n }
\n\/\/ … existing code …<\/p>\n
\u8fd9\u91cc\u7684\u6bd4\u8f83\u903b\u8f91\u975e\u5e38\u5173\u952e：<\/p>\n
equals(Object obj)\u00a0\u548c\u00a0hashCode():<\/p>\n
\/\/ … existing code …
\n @Override
\n public int hashCode() {
\n return (int) (accessTime ^ (accessTime >>> 32));
\n }<\/p>\n
@Override
\n public boolean equals(Object obj) {
\n if (this == obj) {
\n return true;
\n }
\n if (obj == null || getClass() != obj.getClass()) {
\n return false;
\n }
\n LruCachedBlock other = (LruCachedBlock) obj;
\n return compareTo(other) == 0;
\n }
\n\/\/ … existing code …<\/p>\n
\u8fd9\u4e24\u4e2a\u65b9\u6cd5\u7684\u5b9e\u73b0\u90fd\u53ea\u4f9d\u8d56\u4e8e\u00a0accessTime\u3002\u8fd9\u610f\u5473\u7740，\u5982\u679c\u4e24\u4e2a\u00a0LruCachedBlock\u00a0\u5b9e\u4f8b\u7684\u00a0accessTime\u00a0\u76f8\u540c，\u5b83\u4eec\u5c31\u88ab\u8ba4\u4e3a\u662f\u00a0equals\u00a0\u7684\u3002\u8fd9\u5728\u901a\u5e38\u7684\u4e1a\u52a1\u5bf9\u8c61\u4e2d\u6bd4\u8f83\u5c11\u89c1（\u901a\u5e38\u4f1a\u57fa\u4e8eID\u6216\u5185\u5bb9），\u4f46\u5728\u8fd9\u91cc\u662f\u7279\u610f\u4e3a\u4e4b，\u56e0\u4e3a\u5728\u67d0\u4e9b\u7528\u4e8e\u6392\u5e8f\u7684\u6570\u636e\u7ed3\u6784（\u5982\u00a0MinMaxPriorityQueue）\u4e2d，\u5143\u7d20\u7684\u76f8\u7b49\u6027\u5224\u65ad\u548c\u6392\u5e8f\u903b\u8f91\u9700\u8981\u4fdd\u6301\u4e00\u81f4\u3002<\/p>\n<\/li>\n<\/ul>\n
LruCachedBlock\u00a0\u662f\u4e00\u4e2a\u7cbe\u5fc3\u8bbe\u8ba1\u7684\u7c7b，\u5b83\u4e0d\u4ec5\u4ec5\u662f\u4e00\u4e2a\u6570\u636e\u6301\u6709\u8005，\u66f4\u662f\u00a0LruBlockCache\u00a0\u80fd\u591f\u5b9e\u73b0\u9ad8\u6548\u3001\u5e26\u4f18\u5148\u7ea7\u7684 LRU \u6dd8\u6c70\u7b56\u7565\u7684\u6838\u5fc3\u7ec4\u4ef6\u3002\u5b83\u901a\u8fc7：<\/p>\n
\u901a\u8fc7\u5c06\u8fd9\u4e9b\u903b\u8f91\u5185\u805a\u5728\u00a0LruCachedBlock\u00a0\u5185\u90e8，\u4f7f\u5f97\u4e0a\u5c42\u7684\u00a0LruBlockCache\u00a0\u548c\u00a0LruAdaptiveBlockCache\u00a0\u7684\u5b9e\u73b0\u53ef\u4ee5\u66f4\u52a0\u6e05\u6670，\u4e13\u6ce8\u4e8e\u7f13\u5b58\u7684\u5b8f\u89c2\u7ba1\u7406\u548c\u5e76\u53d1\u63a7\u5236，\u800c\u5c06\u5355\u4e2a\u7f13\u5b58\u6761\u76ee\u7684\u72b6\u6001\u548c\u884c\u4e3a\u4ea4\u7531\u00a0LruCachedBlock\u00a0\u81ea\u5df1\u7ba1\u7406\u3002<\/p>\n
LruBlockCache\u00a0\u662f Apache HBase \u4e2d\u9ed8\u8ba4\u7684\u3001\u57fa\u4e8e\u5806\u5185\u5185\u5b58\u7684 Block Cache（\u5757\u7f13\u5b58）\u5b9e\u73b0\u3002\u5b83\u662f\u4e00\u4e2a\u81f3\u5173\u91cd\u8981\u7684\u7ec4\u4ef6，\u76f4\u63a5\u5f71\u54cd HBase \u7684\u8bfb\u53d6\u6027\u80fd\u3002\u5b83\u7684\u6838\u5fc3\u76ee\u6807\u662f\u5c06\u5728 HDFS \u4e2d\u8bfb\u53d6\u8fc7\u7684\u70ed\u70b9\u6570\u636e\u5757（HFile Block）\u7f13\u5b58\u5728 RegionServer \u7684 JVM \u5806\u5185\u5b58\u4e2d，\u4ece\u800c\u907f\u514d\u4e0b\u4e00\u6b21\u8bfb\u53d6\u76f8\u540c\u6570\u636e\u65f6\u6602\u8d35\u7684\u78c1\u76d8 I\/O \u64cd\u4f5c\u3002<\/p>\n
@InterfaceAudience.Private
\npublic class LruBlockCache implements FirstLevelBlockCache {
\n\/\/…
\n}<\/p>\n
LruBlockCache\u00a0\u7684\u8bbe\u8ba1\u7cbe\u9ad3\u5728\u4e8e\u5b83\u5e76\u975e\u4e00\u4e2a\u7b80\u5355\u7684 LRU \u7f13\u5b58，\u800c\u662f\u878d\u5408\u4e86\u5e76\u53d1\u63a7\u5236\u3001\u4f18\u5148\u7ea7\u548c\u7cbe\u7ec6\u5316\u5185\u5b58\u7ba1\u7406\u7684\u590d\u6742\u7cfb\u7edf\u3002<\/p>\n
\u7f13\u5b58\u7cfb\u7edf\u5fc5\u987b\u652f\u6301\u9ad8\u5e76\u53d1\u7684\u8bfb\u5199\u3002LruBlockCache\u00a0\u4f7f\u7528\u00a0java.util.concurrent.ConcurrentHashMap\u00a0\u4f5c\u4e3a\u5176\u5e95\u5c42\u5b58\u50a8\u7ed3\u6784\u3002<\/p>\n
\/\/ … existing code …
\n \/**
\n * Defined the cache map as {@link ConcurrentHashMap} here, because in
\n * {@link LruBlockCache#getBlock}, we need to guarantee the atomicity of map#k (key, func).
\n * Besides, the func method must execute exactly once only when the key is present and under the
\n * lock context, otherwise the reference count will be messed up. Notice that the
\n * {@link java.util.concurrent.ConcurrentSkipListMap} can not guarantee that. Some code using
\n * #computeIfPresent also expects the supplier to be executed only once. ConcurrentHashMap can
\n * guarantee that. Other types may not.
\n *\/
\n private transient final ConcurrentHashMap<BlockCacheKey, LruCachedBlock> map;
\n\/\/ … existing code …<\/p>\n
\u9009\u62e9\u00a0ConcurrentHashMap\u00a0\u7684\u5173\u952e\u5728\u4e8e\u5176\u00a0computeIfPresent\u00a0\u7b49\u539f\u5b50\u64cd\u4f5c\u65b9\u6cd5，\u8fd9\u80fd\u4fdd\u8bc1\u5728\u201c\u83b7\u53d6\u5e76\u66f4\u65b0\u201d\u4e00\u4e2a\u7f13\u5b58\u5757（\u4f8b\u5982\u66f4\u65b0\u5176\u8bbf\u95ee\u65f6\u95f4）\u8fd9\u4e2a\u590d\u5408\u64cd\u4f5c\u7684\u539f\u5b50\u6027，\u907f\u514d\u4e86\u5728\u9ad8\u5e76\u53d1\u573a\u666f\u4e0b\u4f7f\u7528\u663e\u5f0f\u9501\u5e26\u6765\u7684\u6027\u80fd\u5f00\u9500\u548c\u590d\u6742\u6027\u3002<\/p>\n
\u7eaf\u7cb9\u7684 LRU \u7b97\u6cd5\u5728\u67d0\u4e9b\u573a\u666f\u4e0b\u8868\u73b0\u4e0d\u4f73，\u4f8b\u5982，\u4e00\u6b21\u5927\u7684\u626b\u63cf\u64cd\u4f5c（Scan）\u53ef\u80fd\u4f1a\u8bfb\u5165\u5927\u91cf\u4f4e\u4ef7\u503c\u3001\u53ea\u8bbf\u95ee\u4e00\u6b21\u7684\u6570\u636e\u5757，\u4ece\u800c\u5c06\u771f\u6b63\u9700\u8981\u9891\u7e41\u8bbf\u95ee\u7684\u70ed\u70b9\u6570\u636e\u5757\u201c\u51b2\u5237\u201d\u51fa\u7f13\u5b58\u3002\u4e3a\u4e86\u89e3\u51b3\u8fd9\u4e2a\u95ee\u9898，LruBlockCache\u00a0\u5f15\u5165\u4e86\u4e09\u7ea7\u4f18\u5148\u7ea7：<\/p>\n
\u8fd9\u4e09\u4e2a\u4f18\u5148\u7ea7\u5404\u81ea\u88ab\u5206\u914d\u4e86\u4e00\u5b9a\u6bd4\u4f8b\u7684\u7f13\u5b58\u7a7a\u95f4（\u7531\u914d\u7f6e\u53c2\u6570\u00a0singleFactor,\u00a0multiFactor,\u00a0memoryFactor\u00a0\u51b3\u5b9a），\u6dd8\u6c70\u7b97\u6cd5\u4f1a\u6839\u636e\u6bcf\u4e2a\u4f18\u5148\u7ea7\u5206\u533a\u7684\u4f7f\u7528\u60c5\u51b5\u6765\u516c\u5e73\u5730\u8fdb\u884c\u6dd8\u6c70\u3002<\/p>\n
\u4e3a\u4e86\u4fdd\u8bc1\u00a0cacheBlock\u00a0\u548c\u00a0getBlock\u00a0\u65b9\u6cd5\u7684\u4f4e\u5ef6\u8fdf，\u6dd8\u6c70\u64cd\u4f5c\u5728\u4e00\u4e2a\u72ec\u7acb\u7684\u540e\u53f0\u7ebf\u7a0b (EvictionThread) \u4e2d\u6267\u884c\u3002<\/p>\n
LruBlockCache\u00a0\u5185\u90e8\u6709\u5927\u91cf\u7684\u6210\u5458\u53d8\u91cf\u6765\u7ef4\u62a4\u5176\u72b6\u6001\u548c\u914d\u7f6e\u3002<\/p>\n
\/\/ … existing code …
\n \/** Cache access count (sequential ID) *\/
\n private final AtomicLong count;<\/p>\n
\/** hard capacity limit *\/
\n private float hardCapacityLimitFactor;<\/p>\n
\/** Cache statistics *\/
\n private final CacheStats stats;<\/p>\n
\/** Maximum allowable size of cache (block put if size > max, evict) *\/
\n private long maxSize;<\/p>\n
\/\/ … existing code …
\n \/** Acceptable size of cache (no evictions if size < acceptable) *\/
\n private float acceptableFactor;<\/p>\n
\/** Minimum threshold of cache (when evicting, evict until size < min) *\/
\n private float minFactor;<\/p>\n
\/** Single access bucket size *\/
\n private float singleFactor;<\/p>\n
\/** Multiple access bucket size *\/
\n private float multiFactor;<\/p>\n
\/** In-memory bucket size *\/
\n private float memoryFactor;<\/p>\n
\/\/ … existing code …
\n \/**
\n * Where to send victims (blocks evicted\/missing from the cache). This is used only when we use an
\n * external cache as L2. Note: See org.apache.hadoop.hbase.io.hfile.MemcachedBlockCache
\n *\/
\n private transient BlockCache victimHandler = null;
\n\/\/ … existing code …<\/p>\n
\u8fd9\u662f\u5411\u7f13\u5b58\u4e2d\u6dfb\u52a0\u65b0\u5757\u7684\u5165\u53e3\u3002<\/p>\n
\/\/ … existing code …
\n @Override
\n public void cacheBlock(BlockCacheKey cacheKey, Cacheable buf, boolean inMemory) {
\n if (buf.heapSize() > maxBlockSize) {
\n\/\/ … existing code …
\n return;
\n }<\/p>\n
LruCachedBlock cb = map.get(cacheKey);
\n if (cb != null && !BlockCacheUtil.shouldReplaceExistingCacheBlock(this, cacheKey, buf)) {
\n return;
\n }
\n long currentSize = size.get();
\n long currentAcceptableSize = acceptableSize();
\n long hardLimitSize = (long) (hardCapacityLimitFactor * currentAcceptableSize);
\n if (currentSize >= hardLimitSize) {
\n stats.failInsert();
\n\/\/ … existing code …
\n if (!evictionInProgress) {
\n runEviction();
\n }
\n return;
\n }
\n \/\/ Ensure that the block is an heap one.
\n buf = asReferencedHeapBlock(buf);
\n cb = new LruCachedBlock(cacheKey, buf, count.incrementAndGet(), inMemory);
\n long newSize = updateSizeMetrics(cb, false);
\n map.put(cacheKey, cb);
\n\/\/ … existing code …
\n if (newSize > currentAcceptableSize && !evictionInProgress) {
\n runEviction();
\n }
\n }
\n\/\/ … existing code …<\/p>\n
\u5176\u6267\u884c\u6d41\u7a0b\u5982\u4e0b：<\/p>\n
\u8fd9\u662f\u4ece\u7f13\u5b58\u4e2d\u8bfb\u53d6\u5757\u7684\u5165\u53e3\u3002\u5b83\u5229\u7528\u4e86\u00a0map.computeIfPresent\u00a0\u6765\u539f\u5b50\u5730\u5b8c\u6210\u201c\u83b7\u53d6\u5e76\u66f4\u65b0\u201d\u64cd\u4f5c，\u4fdd\u8bc1\u4e86\u7ebf\u7a0b\u5b89\u5168\u548c\u9ad8\u6027\u80fd\u3002\u5982\u679c\u547d\u4e2d，\u5b83\u4f1a\u66f4\u65b0\u5757\u7684\u00a0accessTime\u00a0\u548c\u4f18\u5148\u7ea7，\u8fd9\u662f LRU \u903b\u8f91\u7684\u6838\u5fc3\u3002<\/p>\n
evict()\u00a0\u65b9\u6cd5\u662f\u00a0LruBlockCache\u00a0\u4e2d\u8d1f\u8d23\u6267\u884c\u7f13\u5b58\u6dd8\u6c70\u7684\u6838\u5fc3\u51fd\u6570\u3002\u5b83\u7684\u4e3b\u8981\u76ee\u6807\u662f\u5f53\u7f13\u5b58\u5927\u5c0f\u8d85\u8fc7\u9884\u8bbe\u7684\u9608\u503c\u65f6，\u901a\u8fc7\u79fb\u9664\u6700\u8fd1\u6700\u5c11\u4f7f\u7528\u7684\u5757（LRU），\u5c06\u7f13\u5b58\u5927\u5c0f\u964d\u4f4e\u5230\u4e00\u4e2a\u53ef\u63a5\u53d7\u7684\u6c34\u5e73\u3002\u8fd9\u4e2a\u8fc7\u7a0b\u662f\u5f02\u6b65\u7684，\u901a\u5e38\u7531\u4e00\u4e2a\u4e13\u95e8\u7684\u00a0EvictionThread\u00a0\u7ebf\u7a0b\u6765\u8c03\u7528，\u4ee5\u907f\u514d\u963b\u585e\u6b63\u5e38\u7684\u7f13\u5b58\u8bfb\u5199\u64cd\u4f5c\u3002<\/p>\n
\u6211\u4eec\u6765\u9010\u6bb5\u5206\u6790\u5b83\u7684\u5b9e\u73b0：<\/p>\n
\/\/ … existing code …
\n void evict() {<\/p>\n
\/\/ Ensure only one eviction at a time
\n if (!evictionLock.tryLock()) {
\n return;
\n }<\/p>\n
try {
\n evictionInProgress = true;
\n long currentSize = this.size.get();
\n long bytesToFree = currentSize – minSize();<\/p>\n
if (LOG.isTraceEnabled()) {
\n\/\/ … existing code …
\n }<\/p>\n
if (bytesToFree <= 0) {
\n return;
\n }<\/p>\n
\/\/ Instantiate priority buckets
\n BlockBucket bucketSingle = new BlockBucket("single", bytesToFree, blockSize, singleSize());
\n BlockBucket bucketMulti = new BlockBucket("multi", bytesToFree, blockSize, multiSize());
\n BlockBucket bucketMemory = new BlockBucket("memory", bytesToFree, blockSize, memorySize());<\/p>\n
\/\/ Scan entire map putting into appropriate buckets
\n for (LruCachedBlock cachedBlock : map.values()) {
\n switch (cachedBlock.getPriority()) {
\n case SINGLE: {
\n bucketSingle.add(cachedBlock);
\n break;
\n }
\n case MULTI: {
\n bucketMulti.add(cachedBlock);
\n break;
\n }
\n case MEMORY: {
\n bucketMemory.add(cachedBlock);
\n break;
\n }
\n }
\n }<\/p>\n
long bytesFreed = 0;
\n if (forceInMemory || memoryFactor > 0.999f) {
\n\/\/ … (special eviction logic) …
\n } else {
\n PriorityQueue<BlockBucket> bucketQueue = new PriorityQueue<>(3);<\/p>\n
bucketQueue.add(bucketSingle);
\n bucketQueue.add(bucketMulti);
\n bucketQueue.add(bucketMemory);<\/p>\n
int remainingBuckets = bucketQueue.size();<\/p>\n
BlockBucket bucket;
\n while ((bucket = bucketQueue.poll()) != null) {
\n long overflow = bucket.overflow();
\n if (overflow > 0) {
\n long bucketBytesToFree =
\n Math.min(overflow, (bytesToFree – bytesFreed) \/ remainingBuckets);
\n bytesFreed += bucket.free(bucketBytesToFree);
\n }
\n remainingBuckets–;
\n }
\n }
\n\/\/ … (logging) …
\n } finally {
\n stats.evict();
\n evictionInProgress = false;
\n evictionLock.unlock();
\n }
\n }
\n\/\/ … existing code …<\/p>\n
\/\/ Ensure only one eviction at a time
\nif (!evictionLock.tryLock()) {
\n return;
\n}<\/p>\n
try {
\n evictionInProgress = true;
\n \/\/ …
\n} finally {
\n \/\/ …
\n evictionInProgress = false;
\n evictionLock.unlock();
\n}<\/p>\n
\u8ba1\u7b97\u9700\u8981\u91ca\u653e\u7684\u7a7a\u95f4<\/p>\n
long currentSize = this.size.get();
\nlong bytesToFree = currentSize – minSize();<\/p>\n
if (bytesToFree <= 0) {
\n return;
\n}<\/p>\n
\u8fd9\u662f\u5b9e\u73b0\u5e26\u4f18\u5148\u7ea7\u6dd8\u6c70\u7b56\u7565\u7684\u6838\u5fc3\u6b65\u9aa4\u3002<\/p>\n
\u6ce8\u610f\u8fd9\u91cc\u7684\u6784\u9020，\u6700\u5c0f\u6700\u5927\u5806\u7684 \u5bb9\u91cf \u5c31\u662f\u00a0bytesToFree，\u5373\u8981\u6dd8\u6c70\u7684\u6570\u91cf，\u662f\u4e00\u4e2atop K\u7528\u6cd5\u3002<\/p>\n
\/\/ Instantiate priority buckets
\nBlockBucket bucketSingle = new BlockBucket("single", bytesToFree, blockSize, singleSize());
\nBlockBucket bucketMulti = new BlockBucket("multi", bytesToFree, blockSize, multiSize());
\nBlockBucket bucketMemory = new BlockBucket("memory", bytesToFree, blockSize, memorySize());<\/p>\n
\/\/ Scan entire map putting into appropriate buckets
\nfor (LruCachedBlock cachedBlock : map.values()) {
\n switch (cachedBlock.getPriority()) {
\n case SINGLE: {
\n bucketSingle.add(cachedBlock);
\n break;
\n }
\n \/\/ … other cases
\n }
\n}<\/p>\n
BlockBucket.add(LruCachedBlock block)<\/p>\n
\/\/ in class BlockBucket
\npublic void add(LruCachedBlock block) {
\n totalSize += block.heapSize();
\n queue.add(block);
\n}<\/p>\n
\u8fd9\u4e2a\u65b9\u6cd5\u5f88\u7b80\u5355，\u5b83\u7d2f\u52a0\u6876\u7684\u603b\u5927\u5c0f，\u5e76\u5c06\u00a0LruCachedBlock\u00a0\u6dfb\u52a0\u5230\u5185\u90e8\u7684\u00a0LruCachedBlockQueue\u00a0\u4e2d\u3002LruCachedBlockQueue\u00a0\u5185\u90e8\u662f\u4e00\u4e2a\u00a0MinMaxPriorityQueue，\u5b83\u4f1a\u6839\u636e\u00a0LruCachedBlock\u00a0\u7684\u00a0compareTo\u00a0\u65b9\u6cd5（\u5373\u6bd4\u8f83\u00a0accessTime）\u6765\u81ea\u52a8\u6392\u5e8f，\u786e\u4fdd\u8bbf\u95ee\u65f6\u95f4\u6700\u8001\u548c\u6700\u65b0\u7684\u5757\u603b\u662f\u5728\u961f\u5217\u7684\u4e24\u7aef，\u53ef\u4ee5\u88ab\u5feb\u901f\u8bbf\u95ee\u5230\u3002<\/p>\n
\u8fd9\u91cc\u6709\u4e24\u79cd\u4e3b\u8981\u7684\u6dd8\u6c70\u903b\u8f91：<\/p>\n
\u9ed8\u8ba4\u6dd8\u6c70\u903b\u8f91<\/p>\n
PriorityQueue<BlockBucket> bucketQueue = new PriorityQueue<>(3);<\/p>\n
bucketQueue.add(bucketSingle);
\nbucketQueue.add(bucketMulti);
\nbucketQueue.add(bucketMemory);<\/p>\n
int remainingBuckets = bucketQueue.size();<\/p>\n
BlockBucket bucket;
\nwhile ((bucket = bucketQueue.poll()) != null) {
\n long overflow = bucket.overflow();
\n if (overflow > 0) {
\n long bucketBytesToFree =
\n Math.min(overflow, (bytesToFree – bytesFreed) \/ remainingBuckets);
\n bytesFreed += bucket.free(bucketBytesToFree);
\n }
\n remainingBuckets–;
\n}<\/p>\n
\u8fd9\u662f\u6807\u51c6\u7684\u3001\u57fa\u4e8e\u201c\u6ea2\u51fa\u201d\u7684\u516c\u5e73\u6dd8\u6c70\u7b97\u6cd5\u3002<\/p>\n
BlockBucket.free(long toFree)<\/p>\n
\/\/ in class BlockBucket
\npublic long free(long toFree) {
\n \/\/ … logging …
\n LruCachedBlock cb;
\n long freedBytes = 0;
\n while ((cb = queue.pollLast()) != null) {
\n freedBytes += evictBlock(cb, true);
\n if (freedBytes >= toFree) {
\n return freedBytes;
\n }
\n }
\n \/\/ … logging …
\n return freedBytes;
\n}<\/p>\n
\u4f18\u5148\u4fdd\u62a4\u5185\u5b58\u4e2d（in-memory）\u6570\u636e\u5757\u7684\u7279\u6b8a\u6dd8\u6c70\u6a21\u5f0f\u3002<\/p>\n
\u8fd9\u4e2a\u903b\u8f91\u7684\u89e6\u53d1\u6761\u4ef6\u662f：<\/p>\n
if (forceInMemory || memoryFactor > 0.999f)<\/p>\n
\u5f53\u6ee1\u8db3\u4ee5\u4e0a\u4efb\u4e00\u6761\u4ef6\u65f6，\u5c31\u4f1a\u8fdb\u5165\u8fd9\u4e2a\u7279\u6b8a\u7684\u6dd8\u6c70\u903b\u8f91，\u5176\u6838\u5fc3\u601d\u60f3\u662f：\u5c3d\u53ef\u80fd\u5730\u907f\u514d\u6dd8\u6c70 "memory" \u7c7b\u578b\u7684\u7f13\u5b58\u5757，\u4f18\u5148\u6dd8\u6c70 "single-access" \u548c "multi-access" \u7c7b\u578b\u7684\u7f13\u5b58\u5757\u3002<\/p>\n
\u8fd9\u4e2a\u903b\u8f91\u5185\u90e8\u5206\u4e3a\u4e24\u79cd\u60c5\u51b5：<\/p>\n
\u4e0d\u5f97\u4e0d\u6dd8\u6c70 "memory" \u5757\u7684\u60c5\u51b5<\/p>\n
if (bytesToFree > (s + m)) {
\n \/\/ …
\n}<\/p>\n
\u8fd9\u4e2a\u00a0if\u00a0\u6761\u4ef6\u610f\u5473\u7740，\u5373\u4f7f\u628a "single" \u548c "multi" \u6876\u91cc\u7684\u5757\u5168\u90e8\u6e05\u7a7a，\u4e5f\u65e0\u6cd5\u6ee1\u8db3\u9700\u8981\u91ca\u653e\u7684\u7a7a\u95f4\u5927\u5c0f\u3002\u5728\u8fd9\u79cd\u60c5\u51b5\u4e0b，\u4ee3\u7801\u4f1a： a. \u9996\u5148\u6e05\u7a7a\u00a0bucketSingle\u00a0\u548c\u00a0bucketMulti\u3002 b. \u7136\u540e\u4ece\u00a0bucketMemory\u00a0\u4e2d\u6dd8\u6c70\u6389\u5269\u4f59\u9700\u8981\u91ca\u653e\u7684\u7a7a\u95f4\u3002 \u8fd9\u6e05\u6670\u5730\u4f53\u73b0\u4e86\u5bf9 "memory" \u5757\u7684\u4fdd\u62a4：\u53ea\u6709\u5728\u4e07\u4e0d\u5f97\u5df2\u65f6\u624d\u52a8\u5b83\u3002<\/p>\n<\/li>\n
\u4e0d\u9700\u8981\u6dd8\u6c70 "memory" \u5757\u7684\u60c5\u51b5<\/p>\n
\u8fd9\u79cd\u60c5\u51b5\u610f\u5473\u7740，\u4ec5\u4ece "single" \u548c "multi" \u6876\u4e2d\u6dd8\u6c70\u5757\u5c31\u8db3\u4ee5\u91ca\u653e\u6240\u9700\u7a7a\u95f4\u3002\u6b64\u65f6，\u4ee3\u7801\u7684\u76ee\u6807\u662f\u5728\u5b8c\u6210\u6dd8\u6c70\u540e，\u5c3d\u529b\u7ef4\u6301 "single" \u6876\u548c "multi" \u6876\u7684\u5927\u5c0f\u6bd4\u4f8b\u4e3a 1:2\u3002<\/p>\n
evictBlock(LruCachedBlock block, boolean evictedByEvictionProcess)<\/p>\n
\/\/ in class LruBlockCache
\nprotected long evictBlock(LruCachedBlock block, boolean evictedByEvictionProcess) {
\n final MutableBoolean evicted = new MutableBoolean(false);
\n map.computeIfPresent(block.getCacheKey(), (k, v) -> {
\n if (evictedByEvictionProcess && victimHandler != null) {
\n victimHandler.cacheBlock(k, v.getBuffer());
\n }
\n v.getBuffer().release();
\n evicted.setTrue();
\n return null;
\n });
\n if (evicted.isFalse()) {
\n return 0;
\n }
\n \/\/ … update metrics …
\n return block.heapSize();
\n}<\/p>\n
\u8fd9\u662f\u79fb\u9664\u5355\u4e2a\u5757\u7684\u6700\u7ec8\u5b9e\u73b0，\u975e\u5e38\u5173\u952e：<\/p>\n
} finally {
\n stats.evict();
\n evictionInProgress = false;
\n evictionLock.unlock();
\n}<\/p>\n
\u5728\u00a0finally\u00a0\u5757\u4e2d：<\/p>\n
LruBlockCache.evict()\u00a0\u662f\u4e00\u4e2a\u8bbe\u8ba1\u7cbe\u826f\u3001\u903b\u8f91\u590d\u6742\u7684\u51fd\u6570，\u5b83\u5b8c\u7f8e\u5730\u4f53\u73b0\u4e86\u8be5\u7f13\u5b58\u7cfb\u7edf\u7684\u6838\u5fc3\u601d\u60f3：<\/p>\n
\u6574\u4e2a\u6d41\u7a0b\u4ece\u5b8f\u89c2\u7684\u52a0\u9501\u3001\u8ba1\u7b97，\u5230\u4e2d\u89c2\u7684\u5206\u6876\u3001\u6392\u5e8f，\u518d\u5230\u5fae\u89c2\u7684\u539f\u5b50\u79fb\u9664\u548c\u5f15\u7528\u8ba1\u6570\u7ba1\u7406，\u5c42\u5c42\u9012\u8fdb，\u903b\u8f91\u4e25\u8c28，\u662f\u7406\u89e3 HBase \u9ad8\u6027\u80fd\u7f13\u5b58\u5b9e\u73b0\u7684\u5173\u952e\u3002<\/p>\n
\u5728\u00a0single（\u5355\u6b21\u8bbf\u95ee）\u3001multi（\u591a\u6b21\u8bbf\u95ee）\u548c\u00a0in-memory（\u5185\u5b58\u4e2d）\u4e4b\u95f4\u8f6c\u6362\u7684\u3002<\/p>\n
\u8fd9\u4e2a\u8f6c\u6362\u903b\u8f91\u4e3b\u8981\u7531\u00a0LruBlockCache\u00a0\u7684\u8bbe\u8ba1\u51b3\u5b9a，\u5176\u76ee\u7684\u662f\u4e3a\u4e86\u5728\u7f13\u5b58\u4e2d\u66f4\u597d\u5730\u533a\u5206\u4e0d\u540c\u8bbf\u95ee\u6a21\u5f0f\u7684\u6570\u636e，\u9632\u6b62\u5076\u7136\u7684\u5927\u91cf\u626b\u63cf（scan）\u64cd\u4f5c\u6c61\u67d3\u6574\u4e2a\u7f13\u5b58，\u4ece\u800c\u63d0\u9ad8\u7f13\u5b58\u547d\u4e2d\u7387\u3002<\/p>\n
\u5f53\u4e00\u4e2a block \u9996\u6b21\u88ab\u653e\u5165\u7f13\u5b58\u65f6，\u5b83\u7684\u521d\u59cb\u4f18\u5148\u7ea7\u5c31\u88ab\u786e\u5b9a\u4e86\u3002\u8fd9\u4e3b\u8981\u53d1\u751f\u5728\u00a0cacheBlock\u00a0\u65b9\u6cd5\u4e2d\u3002<\/p>\n
\/\/ … existing code …
\n @Override
\n public void cacheBlock(BlockCacheKey cacheKey, Cacheable buf, boolean inMemory) {
\n if (buf.heapSize() > maxBlockSize) {
\n\/\/ … existing code …
\n return;
\n }<\/p>\n
\/\/ … existing code …
\n \/\/ Ensure that the block is an heap one.
\n buf = asReferencedHeapBlock(buf);
\n cb = new LruCachedBlock(cacheKey, buf, count.incrementAndGet(), inMemory);
\n long newSize = updateSizeMetrics(cb, false);
\n map.put(cacheKey, cb);
\n\/\/ … existing code …
\n }
\n\/\/ … existing code …<\/p>\n
\u4ece\u00a0cacheBlock\u00a0\u65b9\u6cd5\u7684\u7b7e\u540d\u548c\u5b9e\u73b0\u53ef\u4ee5\u770b\u51fa：<\/p>\n
\u5f53\u4e00\u4e2a\u5df2\u7ecf\u662f\u00a0SINGLE\u00a0\u4f18\u5148\u7ea7\u7684 block \u88ab\u518d\u6b21\u8bbf\u95ee\u65f6，\u5b83\u7684\u4f18\u5148\u7ea7\u4f1a\u88ab\u63d0\u5347\u4e3a\u00a0MULTI\u3002\u8fd9\u4e2a\u903b\u8f91\u53d1\u751f\u5728\u00a0getBlock\u00a0\u65b9\u6cd5\u4e2d\u3002<\/p>\n
\/\/ … existing code …
\n @Override
\n public Cacheable getBlock(BlockCacheKey cacheKey, boolean caching, boolean repeat,
\n boolean updateCacheMetrics) {
\n \/\/ Note: 'map' must be a ConcurrentHashMap or the supplier may be invoked more than once.
\n LruCachedBlock cb = map.computeIfPresent(cacheKey, (key, val) -> {
\n\/\/ … existing code …
\n val.getBuffer().retain();
\n return val;
\n });
\n if (cb == null) {
\n\/\/ … existing code …
\n return null;
\n }
\n if (updateCacheMetrics) {
\n stats.hit(caching, cacheKey.isPrimary(), cacheKey.getBlockType());
\n }
\n cb.access(count.incrementAndGet());
\n return cb.getBuffer();
\n }
\n\/\/ … existing code …<\/p>\n
\u5f53\u00a0getBlock\u00a0\u65b9\u6cd5\u6210\u529f\u5728\u7f13\u5b58\u4e2d\u627e\u5230\u4e00\u4e2a block（\u5373\u7f13\u5b58\u547d\u4e2d）\u65f6，\u4f1a\u8c03\u7528\u00a0cb.access(…)\u00a0\u65b9\u6cd5\u3002\u8fd9\u4e2a\u00a0access\u00a0\u65b9\u6cd5（\u5728\u00a0LruCachedBlock\u00a0\u5185\u90e8\u5b9e\u73b0，\u5176\u884c\u4e3a\u5728\u00a0LruBlockCache\u00a0\u7684\u7c7b\u6ce8\u91ca\u4e2d\u6709\u8be6\u7ec6\u63cf\u8ff0）\u4f1a\u68c0\u67e5\u5f53\u524d block \u7684\u4f18\u5148\u7ea7：<\/p>\n
\/**
\n * Block has been accessed.
\n * @param accessTime Last access; this is actually a incremented sequence number rather than an
\n * actual time.
\n *\/
\n public void access(long accessTime) {
\n this.accessTime = accessTime;
\n if (this.priority == BlockPriority.SINGLE) {
\n this.priority = BlockPriority.MULTI;
\n }
\n }<\/p>\n
block \u7684\u4f18\u5148\u7ea7\u8f6c\u6362\u8def\u5f84\u662f\u5355\u5411\u7684：<\/p>\n
\u9996\u6b21\u7f13\u5b58:<\/p>\n
\u540e\u7eed\u8bbf\u95ee:<\/p>\n
\u4e00\u65e6\u4e00\u4e2a block \u7684\u4f18\u5148\u7ea7\u53d8\u4e3a\u00a0MULTI\u00a0\u6216\u00a0MEMORY，\u5b83\u5c31\u4e0d\u4f1a\u518d\u964d\u7ea7\u3002\u8fd9\u79cd\u673a\u5236\u786e\u4fdd\u4e86\u9891\u7e41\u8bbf\u95ee\u7684\u201c\u70ed\u201d\u6570\u636e\u548c\u914d\u7f6e\u4e3a\u5e38\u9a7b\u5185\u5b58\u7684\u6570\u636e\u80fd\u591f\u6709\u66f4\u9ad8\u7684\u6982\u7387\u4fdd\u7559\u5728\u7f13\u5b58\u4e2d，\u800c\u53ea\u88ab\u8bbf\u95ee\u4e00\u6b21\u7684\u201c\u51b7\u201d\u6570\u636e（\u5982\u5168\u8868\u626b\u63cf\u4ea7\u751f\u7684\u6570\u636e）\u5219\u66f4\u5bb9\u6613\u88ab\u6dd8\u6c70\u3002<\/p>\n
LruBlockCache\u00a0\u662f\u4e00\u4e2a\u9ad8\u5ea6\u4f18\u5316\u7684\u3001\u751f\u4ea7\u7ea7\u7684\u7f13\u5b58\u5b9e\u73b0\u3002\u5b83\u901a\u8fc7\u4ee5\u4e0b\u8bbe\u8ba1\u5b9e\u73b0\u4e86\u9ad8\u6027\u80fd\u548c\u9ad8\u6548\u7387：<\/p>\n
\u7406\u89e3\u00a0LruBlockCache\u00a0\u7684\u5de5\u4f5c\u539f\u7406\u5bf9\u4e8e HBase \u7684\u6027\u80fd\u8c03\u4f18\u548c\u95ee\u9898\u8bca\u65ad\u81f3\u5173\u91cd\u8981\u3002<\/p>\n
LruCachedBlockQueue\u00a0\u662f HBase \u4e2d\u00a0LruBlockCache\u00a0\u6dd8\u6c70\u673a\u5236\u7684\u4e00\u4e2a\u5173\u952e\u8f85\u52a9\u7c7b\u3002\u5b83\u5e76\u4e0d\u662f\u4e00\u4e2a\u901a\u7528\u7684\u961f\u5217，\u800c\u662f\u4e3a\u4e00\u4e2a\u975e\u5e38\u7279\u5b9a\u7684\u573a\u666f\u8bbe\u8ba1\u7684：\u5728\u5185\u5b58\u5927\u5c0f\u53d7\u9650\u7684\u60c5\u51b5\u4e0b，\u7ef4\u62a4\u4e00\u7ec4\u201c\u6700\u4f18\u201d\u7684\u5143\u7d20\u3002\u5728\u00a0LruBlockCache\u00a0\u7684\u4e0a\u4e0b\u6587\u4e2d，\u8fd9\u4e2a\u201c\u6700\u4f18\u201d\u6307\u7684\u662f \u8bbf\u95ee\u65f6\u95f4\u6700\u65b0（accessTime \u6700\u5927） \u7684\u00a0LruCachedBlock\u00a0\u96c6\u5408\u3002<\/p>\n
\u4e0b\u9762\u6211\u4eec\u4ece\u5b83\u7684\u8bbe\u8ba1\u76ee\u6807\u3001\u6838\u5fc3\u6570\u636e\u7ed3\u6784\u3001\u6784\u9020\u51fd\u6570\u548c\u5173\u952e\u65b9\u6cd5\u7b49\u65b9\u9762\u6765\u6df1\u5165\u5256\u6790\u3002<\/p>\n
@InterfaceAudience.Private
\npublic class LruCachedBlockQueue implements HeapSize {
\n\/\/…
\n}<\/p>\n
\u5b83\u7684\u6838\u5fc3\u8bbe\u8ba1\u76ee\u6807\u5728\u7c7b\u7684\u6ce8\u91ca\u4e2d\u6709\u6e05\u6670\u7684\u63cf\u8ff0：<\/p>\n
A memory-bound queue that will grow until an element brings total size >= maxSize. From then on, only entries that are sorted larger than the smallest current entry will be inserted\/replaced.<\/p>\n
\u7ffb\u8bd1\u8fc7\u6765\u5c31\u662f：\u4e00\u4e2a\u53d7\u5185\u5b58\u9650\u5236\u7684\u961f\u5217\u3002\u5b83\u4f1a\u4e00\u76f4\u589e\u957f，\u76f4\u5230\u5185\u90e8\u6240\u6709\u5143\u7d20\u7684\u603b\u5927\u5c0f（heapSize）\u8d85\u8fc7\u4e86\u8bbe\u5b9a\u7684\u00a0maxSize\u3002\u4ece\u90a3\u4e00\u523b\u8d77，\u53ea\u6709\u5f53\u4e00\u4e2a\u65b0\u5143\u7d20\u7684\u6392\u5e8f（compareTo\u00a0\u7684\u7ed3\u679c）\u6bd4\u961f\u5217\u4e2d\u5f53\u524d\u6700\u5c0f\u7684\u5143\u7d20\u8fd8\u8981\u5927\u65f6，\u624d\u4f1a\u88ab\u8003\u8651\u52a0\u5165\u961f\u5217（\u5e76\u53ef\u80fd\u66ff\u6362\u6389\u6700\u5c0f\u7684\u5143\u7d20）\u3002<\/p>\n
\u8fd9\u4e2a\u7c7b\u7684\u4f5c\u7528\u662f\u5728\u00a0LruBlockCache\u00a0\u7684\u00a0evict()\u00a0\u8fc7\u7a0b\u4e2d，\u4e3a\u6bcf\u4e2a\u4f18\u5148\u7ea7（SINGLE,\u00a0MULTI,\u00a0MEMORY）\u7684\u00a0BlockBucket\u00a0\u4e34\u65f6\u5b58\u653e\u8be5\u4f18\u5148\u7ea7\u7684\u5168\u90e8\u00a0LruCachedBlock，\u5e76\u80fd\u5feb\u901f\u5730\u4ece\u4e2d\u627e\u5230\u5e76\u79fb\u9664\u6700\u8fd1\u6700\u5c11\u4f7f\u7528（accessTime\u00a0\u6700\u5c0f）\u7684\u5757\u3002<\/p>\n
\/\/ … existing code …
\n private MinMaxPriorityQueue<LruCachedBlock> queue;<\/p>\n
private long heapSize;
\n private long maxSize;
\n\/\/ … existing code …<\/p>\n
\/\/ … existing code …
\n public LruCachedBlockQueue(long maxSize, long blockSize) {
\n Preconditions.checkArgument(blockSize > 0, "negative blockSize %s", blockSize);
\n Preconditions.checkArgument(maxSize > 0, "negative maxSize %s", maxSize);
\n int initialSize = (int) (maxSize \/ blockSize);
\n if (initialSize == 0) {
\n initialSize++;
\n }
\n queue = MinMaxPriorityQueue.expectedSize(initialSize).create();
\n heapSize = 0;
\n this.maxSize = maxSize;
\n }
\n\/\/ … existing code …<\/p>\n
\u6784\u9020\u51fd\u6570\u4e3b\u8981\u505a\u521d\u59cb\u5316\u5de5\u4f5c：<\/p>\n
\u8fd9\u662f\u8fd9\u4e2a\u7c7b\u4e2d\u6700\u6838\u5fc3\u3001\u903b\u8f91\u6700\u590d\u6742\u7684\u65b9\u6cd5\u3002\u5b83\u5b9a\u4e49\u4e86\u5143\u7d20\u5982\u4f55\u88ab\u6dfb\u52a0\u5230\u8fd9\u4e2a\u53d7\u9650\u961f\u5217\u4e2d\u3002<\/p>\n
\/\/ … existing code …
\n public void add(LruCachedBlock cb) {
\n if (heapSize < maxSize) {
\n queue.add(cb);
\n heapSize += cb.heapSize();
\n } else {
\n LruCachedBlock head = queue.peek();
\n if (cb.compareTo(head) > 0) {
\n heapSize += cb.heapSize();
\n heapSize -= head.heapSize();
\n if (heapSize > maxSize) {
\n queue.poll();
\n } else {
\n heapSize += head.heapSize();
\n }
\n queue.add(cb);
\n }
\n }
\n }
\n\/\/ … existing code …<\/p>\n
\u8be5\u65b9\u6cd5\u5206\u4e3a\u4e24\u79cd\u60c5\u51b5：<\/p>\n
heapSize < maxSize\u00a0(\u961f\u5217\u672a\u6ee1):<\/p>\n
heapSize >= maxSize\u00a0(\u961f\u5217\u5df2\u6ee1\u6216\u8d85\u9650):<\/p>\n
\u6ce8\u610f:\u00a0add\u00a0\u65b9\u6cd5\u7684\u903b\u8f91\u5728\u00a0LruBlockCache\u00a0\u7684\u00a0evict\u00a0\u573a\u666f\u4e0b\u662f\u6b63\u786e\u7684，\u56e0\u4e3a\u00a0evict\u00a0\u53ea\u662f\u7528\u8fd9\u4e2a\u961f\u5217\u6765\u7ef4\u62a4top K \u5f85\u6dd8\u6c70\u5143\u7d20，\u4e4b\u540e\u4f1a\u901a\u8fc7\u00a0pollLast\u00a0\u6765\u4e3b\u52a8\u79fb\u9664\u5143\u7d20\u3002<\/p>\n
\u8fd9\u662f\u5728\u6784\u5efa\u6dd8\u6c70\u5019\u9009\u6c60，\u5982\u679c\u6c60\u5b50\u6ee1\u4e86，\u6bcf\u5f53\u9047\u5230\u4e00\u4e2a\u65b0\u5757，\u5c31\u548c\u6c60\u91cc\u6700\u5e74\u8f7b\u7684\u90a3\u4e2a\u5019\u9009\u8005（head）\u6bd4\u8f83\u3002\u5982\u679c\u65b0\u5757\u6bd4\u5b83\u8fd8\u8001，\u5c31\u8bf4\u660e\u65b0\u5757\u66f4\u5e94\u8be5\u88ab\u6dd8\u6c70，\u4e8e\u662f\u7528\u65b0\u5757\u6362\u6389\u90a3\u4e2a\u6700\u5e74\u8f7b\u7684\u5019\u9009\u8005\u3002\u8fd9\u4e2a\u201c\u6362\u6389\u201d\u7684\u64cd\u4f5c，\u5c31\u662f\u901a\u8fc7 poll() \u79fb\u9664 head，\u518d add(cb) \u5b9e\u73b0\u7684\u3002<\/p>\n<\/p>\n
\/\/ … existing code …
\n \/** Returns The next element in this queue, or {@code null} if the queue is empty. *\/
\n public LruCachedBlock poll() {
\n return queue.poll();
\n }<\/p>\n
\/** Returns The last element in this queue, or {@code null} if the queue is empty. *\/
\n public LruCachedBlock pollLast() {
\n return queue.pollLast();
\n }
\n\/\/ … existing code …<\/p>\n
\u8ba9\u6211\u4eec\u518d\u6b21\u786e\u8ba4\u00a0LruCachedBlock.compareTo\u00a0\u7684\u5b9e\u73b0：<\/p>\n
public int compareTo(LruCachedBlock that) {
\n if (this.accessTime == that.accessTime) return 0;
\n return this.accessTime < that.accessTime ? 1 : -1;
\n}<\/p>\n
this.accessTime < that.accessTime\u00a0(this\u66f4\u8001) -> \u8fd4\u56de 1\u3002\u5728\u00a0PriorityQueue\u00a0\u4e2d，\u8fd4\u56de\u503c\u5927\u4e8e0\u610f\u5473\u7740\u00a0this\u00a0\u7684\u4f18\u5148\u7ea7\u66f4\u4f4e，\u4f1a\u6392\u5728\u540e\u9762\u3002\u6240\u4ee5\u00a0poll()\u00a0\u4f1a\u53d6\u51fa\u00a0accessTime\u00a0\u6700\u5927\u7684（\u6700\u65b0\u7684），pollLast()\u00a0\u4f1a\u53d6\u51fa\u00a0accessTime\u00a0\u6700\u5c0f\u7684（\u6700\u8001\u7684）\u3002BlockBucket.free()\u00a0\u4e2d\u8c03\u7528\u00a0queue.pollLast()\u00a0\u662f\u6b63\u786e\u7684，\u5b83\u786e\u5b9e\u5728\u6dd8\u6c70\u6700\u8001\u7684\u5757\u3002<\/p>\n
LruCachedBlockQueue\u00a0\u662f\u4e00\u4e2a\u9ad8\u5ea6\u7279\u5316\u7684\u6570\u636e\u7ed3\u6784，\u5b83\u5de7\u5999\u5730\u5229\u7528\u4e86 Guava \u7684\u00a0MinMaxPriorityQueue\u00a0\u6765\u6ee1\u8db3\u00a0LruBlockCache\u00a0\u6dd8\u6c70\u7b97\u6cd5\u7684\u9700\u6c42\u3002<\/p>\n
\u603b\u800c\u8a00\u4e4b，LruCachedBlockQueue\u00a0\u662f\u00a0LruBlockCache\u00a0\u5b9e\u73b0\u5176\u9ad8\u6548\u3001\u5e26\u4f18\u5148\u7ea7\u7684\u6dd8\u6c70\u7b56\u7565\u7684\u4e00\u4e2a\u4e0d\u53ef\u6216\u7f3a\u7684\u5e95\u5c42\u7ec4\u4ef6\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"
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