[GitHub] eolivelli commented on a change in pull request #513: BOOKKEEPER-1106: Introduce write FileInfo cache and read FileInfo cache

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eolivelli commented on a change in pull request #513: BOOKKEEPER-1106: Introduce write FileInfo cache and read FileInfo cache
URL: https://github.com/apache/bookkeeper/pull/513#discussion_r156700175
 
 

 ##########
 File path: bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/IndexPersistenceMgr.java
 ##########
 @@ -100,71 +118,160 @@ public IndexPersistenceMgr(int pageSize,
         getActiveLedgers();
         ledgerDirsManager.addLedgerDirsListener(getLedgerDirsListener());
 
+        // build the file info cache
+        int concurrencyLevel = Math.max(1, Math.max(conf.getNumAddWorkerThreads(), conf.getNumReadWorkerThreads()));
+        RemovalListener<Long, FileInfo> fileInfoEvictionListener = this::handleLedgerEviction;
+        writeFileInfoCache = buildCache(
+            concurrencyLevel,
+            conf.getFileInfoCacheInitialCapacity(),
+            openFileLimit,
+            conf.getFileInfoMaxIdleTime(),
+            fileInfoEvictionListener);
+        readFileInfoCache = buildCache(
+            concurrencyLevel,
+            2 * conf.getFileInfoCacheInitialCapacity(),
+            2 * openFileLimit,
+            conf.getFileInfoMaxIdleTime(),
+            fileInfoEvictionListener);
+
         // Expose Stats
         evictedLedgersCounter = statsLogger.getCounter(LEDGER_CACHE_NUM_EVICTED_LEDGERS);
-        statsLogger.registerGauge(NUM_OPEN_LEDGERS, new Gauge<Integer>() {
+        pendingGetFileInfoCounter = statsLogger.getCounter(PENDING_GET_FILE_INFO);
+        statsLogger.registerGauge(WRITE_FILE_INFO_CACHE_SIZE, new Gauge<Number>() {
+            @Override
+            public Number getDefaultValue() {
+                return 0;
+            }
+
+            @Override
+            public Number getSample() {
+                return writeFileInfoCache.size();
+            }
+        });
+        statsLogger.registerGauge(READ_FILE_INFO_CACHE_SIZE, new Gauge<Number>() {
             @Override
-            public Integer getDefaultValue() {
+            public Number getDefaultValue() {
                 return 0;
             }
 
             @Override
-            public Integer getSample() {
-                return getNumOpenLedgers();
+            public Number getSample() {
+                return readFileInfoCache.size();
             }
         });
     }
 
-    FileInfo getFileInfo(Long ledger, byte masterKey[]) throws IOException {
-        FileInfo fi = fileInfoCache.get(ledger);
-        if (null == fi) {
-            boolean createdNewFile = false;
-            File lf = null;
-            synchronized (this) {
-                // Check if the index file exists on disk.
-                lf = findIndexFile(ledger);
-                if (null == lf) {
-                    if (null == masterKey) {
-                        throw new Bookie.NoLedgerException(ledger);
+    private static Cache<Long, FileInfo> buildCache(int concurrencyLevel,
+                                            int initialCapacity,
+                                            int maximumSize,
+                                            long expireAfterAccessSeconds,
+                                            RemovalListener<Long, FileInfo> removalListener) {
+        CacheBuilder<Long, FileInfo> builder = CacheBuilder.newBuilder()
+            .concurrencyLevel(concurrencyLevel)
+            .initialCapacity(initialCapacity)
+            .maximumSize(maximumSize)
+            .removalListener(removalListener);
+        if (expireAfterAccessSeconds > 0) {
+            builder.expireAfterAccess(expireAfterAccessSeconds, TimeUnit.SECONDS);
+        }
+        return builder.build();
+    }
+
+    /**
+     * When a ledger is evicted, we need to make sure there's no other thread
+     * trying to get FileInfo for that ledger at the same time when we close
+     * the FileInfo.
+     */
+    private void handleLedgerEviction(RemovalNotification<Long, FileInfo> notification) {
+        FileInfo fileInfo = notification.getValue();
+        Long ledgerId = notification.getKey();
+        if (null == fileInfo || null == notification.getKey()) {
+            return;
+        }
+        if (notification.wasEvicted()) {
+            evictedLedgersCounter.inc();
+            // we need to acquire the write lock in another thread,
+            // otherwise there could be dead lock happening.
+            evictionThreadPool.execute(() -> {
 
 Review comment:
   @ivankelly do your think this can be a blocker for 4.6 release ?
   @jiazhai 

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