| // Copyright (C) 2012 The Android Open Source Project |
| // |
| // 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 |
| // |
| // 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 com.google.gerrit.server.cache.h2; |
| |
| import com.google.common.base.Throwables; |
| import com.google.common.cache.AbstractLoadingCache; |
| import com.google.common.cache.Cache; |
| import com.google.common.cache.CacheLoader; |
| import com.google.common.cache.CacheStats; |
| import com.google.common.cache.LoadingCache; |
| import com.google.common.collect.ImmutableSet; |
| import com.google.common.hash.BloomFilter; |
| import com.google.common.hash.Funnel; |
| import com.google.common.hash.Funnels; |
| import com.google.common.hash.PrimitiveSink; |
| import com.google.gerrit.common.TimeUtil; |
| import com.google.gerrit.server.cache.PersistentCache; |
| import com.google.inject.TypeLiteral; |
| import java.io.IOException; |
| import java.io.InvalidClassException; |
| import java.io.ObjectOutputStream; |
| import java.io.OutputStream; |
| import java.sql.Connection; |
| import java.sql.PreparedStatement; |
| import java.sql.ResultSet; |
| import java.sql.SQLException; |
| import java.sql.Statement; |
| import java.sql.Timestamp; |
| import java.sql.Types; |
| import java.util.Calendar; |
| import java.util.Map; |
| import java.util.concurrent.ArrayBlockingQueue; |
| import java.util.concurrent.BlockingQueue; |
| import java.util.concurrent.Callable; |
| import java.util.concurrent.ExecutionException; |
| import java.util.concurrent.Executor; |
| import java.util.concurrent.Future; |
| import java.util.concurrent.ScheduledExecutorService; |
| import java.util.concurrent.TimeUnit; |
| import java.util.concurrent.atomic.AtomicLong; |
| import org.h2.jdbc.JdbcSQLException; |
| import org.slf4j.Logger; |
| import org.slf4j.LoggerFactory; |
| |
| /** |
| * Hybrid in-memory and database backed cache built on H2. |
| * |
| * <p>This cache can be used as either a recall cache, or a loading cache if a CacheLoader was |
| * supplied to its constructor at build time. Before creating an entry the in-memory cache is |
| * checked for the item, then the database is checked, and finally the CacheLoader is used to |
| * construct the item. This is mostly useful for CacheLoaders that are computationally intensive, |
| * such as the PatchListCache. |
| * |
| * <p>Cache stores and invalidations are performed on a background thread, hiding the latency |
| * associated with serializing the key and value pairs and writing them to the database log. |
| * |
| * <p>A BloomFilter is used around the database to reduce the number of SELECTs issued against the |
| * database for new cache items that have not been seen before, a common operation for the |
| * PatchListCache. The BloomFilter is sized when the cache starts to be 64,000 entries or double the |
| * number of items currently in the database table. |
| * |
| * <p>This cache does not export its items as a ConcurrentMap. |
| * |
| * @see H2CacheFactory |
| */ |
| public class H2CacheImpl<K, V> extends AbstractLoadingCache<K, V> implements PersistentCache { |
| private static final Logger log = LoggerFactory.getLogger(H2CacheImpl.class); |
| |
| private static final ImmutableSet<String> OLD_CLASS_NAMES = |
| ImmutableSet.of("com.google.gerrit.server.change.ChangeKind"); |
| |
| private final Executor executor; |
| private final SqlStore<K, V> store; |
| private final TypeLiteral<K> keyType; |
| private final Cache<K, ValueHolder<V>> mem; |
| |
| H2CacheImpl( |
| Executor executor, |
| SqlStore<K, V> store, |
| TypeLiteral<K> keyType, |
| Cache<K, ValueHolder<V>> mem) { |
| this.executor = executor; |
| this.store = store; |
| this.keyType = keyType; |
| this.mem = mem; |
| } |
| |
| @Override |
| public V getIfPresent(Object objKey) { |
| if (!keyType.getRawType().isInstance(objKey)) { |
| return null; |
| } |
| |
| @SuppressWarnings("unchecked") |
| K key = (K) objKey; |
| |
| ValueHolder<V> h = mem.getIfPresent(key); |
| if (h != null) { |
| return h.value; |
| } |
| |
| if (store.mightContain(key)) { |
| h = store.getIfPresent(key); |
| if (h != null) { |
| mem.put(key, h); |
| return h.value; |
| } |
| } |
| return null; |
| } |
| |
| @Override |
| public V get(K key) throws ExecutionException { |
| if (mem instanceof LoadingCache) { |
| return ((LoadingCache<K, ValueHolder<V>>) mem).get(key).value; |
| } |
| throw new UnsupportedOperationException(); |
| } |
| |
| @Override |
| public V get(K key, Callable<? extends V> valueLoader) throws ExecutionException { |
| return mem.get( |
| key, |
| () -> { |
| if (store.mightContain(key)) { |
| ValueHolder<V> h = store.getIfPresent(key); |
| if (h != null) { |
| return h; |
| } |
| } |
| |
| ValueHolder<V> h = new ValueHolder<>(valueLoader.call()); |
| h.created = TimeUtil.nowMs(); |
| executor.execute(() -> store.put(key, h)); |
| return h; |
| }) |
| .value; |
| } |
| |
| @Override |
| public void put(K key, V val) { |
| final ValueHolder<V> h = new ValueHolder<>(val); |
| h.created = TimeUtil.nowMs(); |
| mem.put(key, h); |
| executor.execute(() -> store.put(key, h)); |
| } |
| |
| @SuppressWarnings("unchecked") |
| @Override |
| public void invalidate(Object key) { |
| if (keyType.getRawType().isInstance(key) && store.mightContain((K) key)) { |
| executor.execute(() -> store.invalidate((K) key)); |
| } |
| mem.invalidate(key); |
| } |
| |
| @Override |
| public void invalidateAll() { |
| store.invalidateAll(); |
| mem.invalidateAll(); |
| } |
| |
| @Override |
| public long size() { |
| return mem.size(); |
| } |
| |
| @Override |
| public CacheStats stats() { |
| return mem.stats(); |
| } |
| |
| @Override |
| public DiskStats diskStats() { |
| return store.diskStats(); |
| } |
| |
| void start() { |
| store.open(); |
| } |
| |
| void stop() { |
| for (Map.Entry<K, ValueHolder<V>> e : mem.asMap().entrySet()) { |
| ValueHolder<V> h = e.getValue(); |
| if (!h.clean) { |
| store.put(e.getKey(), h); |
| } |
| } |
| store.close(); |
| } |
| |
| void prune(ScheduledExecutorService service) { |
| store.prune(mem); |
| |
| Calendar cal = Calendar.getInstance(); |
| cal.set(Calendar.HOUR_OF_DAY, 01); |
| cal.set(Calendar.MINUTE, 0); |
| cal.set(Calendar.SECOND, 0); |
| cal.set(Calendar.MILLISECOND, 0); |
| cal.add(Calendar.DAY_OF_MONTH, 1); |
| |
| long delay = cal.getTimeInMillis() - TimeUtil.nowMs(); |
| @SuppressWarnings("unused") |
| Future<?> possiblyIgnoredError = |
| service.schedule(() -> prune(service), delay, TimeUnit.MILLISECONDS); |
| } |
| |
| static class ValueHolder<V> { |
| final V value; |
| long created; |
| volatile boolean clean; |
| |
| ValueHolder(V value) { |
| this.value = value; |
| } |
| } |
| |
| static class Loader<K, V> extends CacheLoader<K, ValueHolder<V>> { |
| private final Executor executor; |
| private final SqlStore<K, V> store; |
| private final CacheLoader<K, V> loader; |
| |
| Loader(Executor executor, SqlStore<K, V> store, CacheLoader<K, V> loader) { |
| this.executor = executor; |
| this.store = store; |
| this.loader = loader; |
| } |
| |
| @Override |
| public ValueHolder<V> load(K key) throws Exception { |
| if (store.mightContain(key)) { |
| ValueHolder<V> h = store.getIfPresent(key); |
| if (h != null) { |
| return h; |
| } |
| } |
| |
| final ValueHolder<V> h = new ValueHolder<>(loader.load(key)); |
| h.created = TimeUtil.nowMs(); |
| executor.execute(() -> store.put(key, h)); |
| return h; |
| } |
| } |
| |
| private static class KeyType<K> { |
| String columnType() { |
| return "OTHER"; |
| } |
| |
| @SuppressWarnings("unchecked") |
| K get(ResultSet rs, int col) throws SQLException { |
| return (K) rs.getObject(col); |
| } |
| |
| void set(PreparedStatement ps, int col, K value) throws SQLException { |
| ps.setObject(col, value, Types.JAVA_OBJECT); |
| } |
| |
| Funnel<K> funnel() { |
| return new Funnel<K>() { |
| private static final long serialVersionUID = 1L; |
| |
| @Override |
| public void funnel(K from, PrimitiveSink into) { |
| try (ObjectOutputStream ser = new ObjectOutputStream(new SinkOutputStream(into))) { |
| ser.writeObject(from); |
| ser.flush(); |
| } catch (IOException err) { |
| throw new RuntimeException("Cannot hash as Serializable", err); |
| } |
| } |
| }; |
| } |
| |
| @SuppressWarnings("unchecked") |
| static <K> KeyType<K> create(TypeLiteral<K> type) { |
| if (type.getRawType() == String.class) { |
| return (KeyType<K>) STRING; |
| } |
| return (KeyType<K>) OTHER; |
| } |
| |
| static final KeyType<?> OTHER = new KeyType<>(); |
| static final KeyType<String> STRING = |
| new KeyType<String>() { |
| @Override |
| String columnType() { |
| return "VARCHAR(4096)"; |
| } |
| |
| @Override |
| String get(ResultSet rs, int col) throws SQLException { |
| return rs.getString(col); |
| } |
| |
| @Override |
| void set(PreparedStatement ps, int col, String value) throws SQLException { |
| ps.setString(col, value); |
| } |
| |
| @SuppressWarnings("unchecked") |
| @Override |
| Funnel<String> funnel() { |
| Funnel<?> s = Funnels.unencodedCharsFunnel(); |
| return (Funnel<String>) s; |
| } |
| }; |
| } |
| |
| static class SqlStore<K, V> { |
| private final String url; |
| private final KeyType<K> keyType; |
| private final long maxSize; |
| private final long expireAfterWrite; |
| private final BlockingQueue<SqlHandle> handles; |
| private final AtomicLong hitCount = new AtomicLong(); |
| private final AtomicLong missCount = new AtomicLong(); |
| private volatile BloomFilter<K> bloomFilter; |
| private int estimatedSize; |
| |
| SqlStore(String jdbcUrl, TypeLiteral<K> keyType, long maxSize, long expireAfterWrite) { |
| this.url = jdbcUrl; |
| this.keyType = KeyType.create(keyType); |
| this.maxSize = maxSize; |
| this.expireAfterWrite = expireAfterWrite; |
| |
| int cores = Runtime.getRuntime().availableProcessors(); |
| int keep = Math.min(cores, 16); |
| this.handles = new ArrayBlockingQueue<>(keep); |
| } |
| |
| synchronized void open() { |
| if (bloomFilter == null) { |
| bloomFilter = buildBloomFilter(); |
| } |
| } |
| |
| void close() { |
| SqlHandle h; |
| while ((h = handles.poll()) != null) { |
| h.close(); |
| } |
| } |
| |
| boolean mightContain(K key) { |
| BloomFilter<K> b = bloomFilter; |
| if (b == null) { |
| synchronized (this) { |
| b = bloomFilter; |
| if (b == null) { |
| b = buildBloomFilter(); |
| bloomFilter = b; |
| } |
| } |
| } |
| return b == null || b.mightContain(key); |
| } |
| |
| private BloomFilter<K> buildBloomFilter() { |
| SqlHandle c = null; |
| try { |
| c = acquire(); |
| try (Statement s = c.conn.createStatement()) { |
| if (estimatedSize <= 0) { |
| try (ResultSet r = s.executeQuery("SELECT COUNT(*) FROM data")) { |
| estimatedSize = r.next() ? r.getInt(1) : 0; |
| } |
| } |
| |
| BloomFilter<K> b = newBloomFilter(); |
| try (ResultSet r = s.executeQuery("SELECT k FROM data")) { |
| while (r.next()) { |
| b.put(keyType.get(r, 1)); |
| } |
| } catch (JdbcSQLException e) { |
| if (e.getCause() instanceof InvalidClassException) { |
| log.warn( |
| "Entries cached for " |
| + url |
| + " have an incompatible class and can't be deserialized. " |
| + "Cache is flushed."); |
| invalidateAll(); |
| } else { |
| throw e; |
| } |
| } |
| return b; |
| } |
| } catch (SQLException e) { |
| log.warn("Cannot build BloomFilter for " + url + ": " + e.getMessage()); |
| c = close(c); |
| return null; |
| } finally { |
| release(c); |
| } |
| } |
| |
| ValueHolder<V> getIfPresent(K key) { |
| SqlHandle c = null; |
| try { |
| c = acquire(); |
| if (c.get == null) { |
| c.get = c.conn.prepareStatement("SELECT v, created FROM data WHERE k=?"); |
| } |
| keyType.set(c.get, 1, key); |
| try (ResultSet r = c.get.executeQuery()) { |
| if (!r.next()) { |
| missCount.incrementAndGet(); |
| return null; |
| } |
| |
| Timestamp created = r.getTimestamp(2); |
| if (expired(created)) { |
| invalidate(key); |
| missCount.incrementAndGet(); |
| return null; |
| } |
| |
| @SuppressWarnings("unchecked") |
| V val = (V) r.getObject(1); |
| ValueHolder<V> h = new ValueHolder<>(val); |
| h.clean = true; |
| hitCount.incrementAndGet(); |
| touch(c, key); |
| return h; |
| } finally { |
| c.get.clearParameters(); |
| } |
| } catch (SQLException e) { |
| if (!isOldClassNameError(e)) { |
| log.warn("Cannot read cache " + url + " for " + key, e); |
| } |
| c = close(c); |
| return null; |
| } finally { |
| release(c); |
| } |
| } |
| |
| private static boolean isOldClassNameError(Throwable t) { |
| for (Throwable c : Throwables.getCausalChain(t)) { |
| if (c instanceof ClassNotFoundException && OLD_CLASS_NAMES.contains(c.getMessage())) { |
| return true; |
| } |
| } |
| return false; |
| } |
| |
| private boolean expired(Timestamp created) { |
| if (expireAfterWrite == 0) { |
| return false; |
| } |
| long age = TimeUtil.nowMs() - created.getTime(); |
| return 1000 * expireAfterWrite < age; |
| } |
| |
| private void touch(SqlHandle c, K key) throws SQLException { |
| if (c.touch == null) { |
| c.touch = c.conn.prepareStatement("UPDATE data SET accessed=? WHERE k=?"); |
| } |
| try { |
| c.touch.setTimestamp(1, TimeUtil.nowTs()); |
| keyType.set(c.touch, 2, key); |
| c.touch.executeUpdate(); |
| } finally { |
| c.touch.clearParameters(); |
| } |
| } |
| |
| void put(K key, ValueHolder<V> holder) { |
| if (holder.clean) { |
| return; |
| } |
| |
| BloomFilter<K> b = bloomFilter; |
| if (b != null) { |
| b.put(key); |
| bloomFilter = b; |
| } |
| |
| SqlHandle c = null; |
| try { |
| c = acquire(); |
| if (c.put == null) { |
| c.put = |
| c.conn.prepareStatement("MERGE INTO data (k, v, created, accessed) VALUES(?,?,?,?)"); |
| } |
| try { |
| keyType.set(c.put, 1, key); |
| c.put.setObject(2, holder.value, Types.JAVA_OBJECT); |
| c.put.setTimestamp(3, new Timestamp(holder.created)); |
| c.put.setTimestamp(4, TimeUtil.nowTs()); |
| c.put.executeUpdate(); |
| holder.clean = true; |
| } finally { |
| c.put.clearParameters(); |
| } |
| } catch (SQLException e) { |
| log.warn("Cannot put into cache " + url, e); |
| c = close(c); |
| } finally { |
| release(c); |
| } |
| } |
| |
| void invalidate(K key) { |
| SqlHandle c = null; |
| try { |
| c = acquire(); |
| invalidate(c, key); |
| } catch (SQLException e) { |
| log.warn("Cannot invalidate cache " + url, e); |
| c = close(c); |
| } finally { |
| release(c); |
| } |
| } |
| |
| private void invalidate(SqlHandle c, K key) throws SQLException { |
| if (c.invalidate == null) { |
| c.invalidate = c.conn.prepareStatement("DELETE FROM data WHERE k=?"); |
| } |
| try { |
| keyType.set(c.invalidate, 1, key); |
| c.invalidate.executeUpdate(); |
| } finally { |
| c.invalidate.clearParameters(); |
| } |
| } |
| |
| void invalidateAll() { |
| SqlHandle c = null; |
| try { |
| c = acquire(); |
| try (Statement s = c.conn.createStatement()) { |
| s.executeUpdate("DELETE FROM data"); |
| } |
| bloomFilter = newBloomFilter(); |
| } catch (SQLException e) { |
| log.warn("Cannot invalidate cache " + url, e); |
| c = close(c); |
| } finally { |
| release(c); |
| } |
| } |
| |
| void prune(Cache<K, ?> mem) { |
| SqlHandle c = null; |
| try { |
| c = acquire(); |
| try (Statement s = c.conn.createStatement()) { |
| long used = 0; |
| try (ResultSet r = s.executeQuery("SELECT SUM(space) FROM data")) { |
| used = r.next() ? r.getLong(1) : 0; |
| } |
| if (used <= maxSize) { |
| return; |
| } |
| |
| try (ResultSet r = |
| s.executeQuery( |
| "SELECT" + " k" + ",space" + ",created" + " FROM data" + " ORDER BY accessed")) { |
| while (maxSize < used && r.next()) { |
| K key = keyType.get(r, 1); |
| Timestamp created = r.getTimestamp(3); |
| if (mem.getIfPresent(key) != null && !expired(created)) { |
| touch(c, key); |
| } else { |
| invalidate(c, key); |
| used -= r.getLong(2); |
| } |
| } |
| } |
| } |
| } catch (SQLException e) { |
| log.warn("Cannot prune cache " + url, e); |
| c = close(c); |
| } finally { |
| release(c); |
| } |
| } |
| |
| DiskStats diskStats() { |
| long size = 0; |
| long space = 0; |
| SqlHandle c = null; |
| try { |
| c = acquire(); |
| try (Statement s = c.conn.createStatement(); |
| ResultSet r = s.executeQuery("SELECT" + " COUNT(*)" + ",SUM(space)" + " FROM data")) { |
| if (r.next()) { |
| size = r.getLong(1); |
| space = r.getLong(2); |
| } |
| } |
| } catch (SQLException e) { |
| log.warn("Cannot get DiskStats for " + url, e); |
| c = close(c); |
| } finally { |
| release(c); |
| } |
| return new DiskStats(size, space, hitCount.get(), missCount.get()); |
| } |
| |
| private SqlHandle acquire() throws SQLException { |
| SqlHandle h = handles.poll(); |
| return h != null ? h : new SqlHandle(url, keyType); |
| } |
| |
| private void release(SqlHandle h) { |
| if (h != null && !handles.offer(h)) { |
| h.close(); |
| } |
| } |
| |
| private SqlHandle close(SqlHandle h) { |
| if (h != null) { |
| h.close(); |
| } |
| return null; |
| } |
| |
| private BloomFilter<K> newBloomFilter() { |
| int cnt = Math.max(64 * 1024, 2 * estimatedSize); |
| return BloomFilter.create(keyType.funnel(), cnt); |
| } |
| } |
| |
| static class SqlHandle { |
| private final String url; |
| Connection conn; |
| PreparedStatement get; |
| PreparedStatement put; |
| PreparedStatement touch; |
| PreparedStatement invalidate; |
| |
| SqlHandle(String url, KeyType<?> type) throws SQLException { |
| this.url = url; |
| this.conn = org.h2.Driver.load().connect(url, null); |
| try (Statement stmt = conn.createStatement()) { |
| stmt.addBatch( |
| "CREATE TABLE IF NOT EXISTS data" |
| + "(k " |
| + type.columnType() |
| + " NOT NULL PRIMARY KEY HASH" |
| + ",v OTHER NOT NULL" |
| + ",created TIMESTAMP NOT NULL" |
| + ",accessed TIMESTAMP NOT NULL" |
| + ")"); |
| stmt.addBatch( |
| "ALTER TABLE data ADD COLUMN IF NOT EXISTS " |
| + "space BIGINT AS OCTET_LENGTH(k) + OCTET_LENGTH(v)"); |
| stmt.executeBatch(); |
| } |
| } |
| |
| void close() { |
| get = closeStatement(get); |
| put = closeStatement(put); |
| touch = closeStatement(touch); |
| invalidate = closeStatement(invalidate); |
| |
| if (conn != null) { |
| try { |
| conn.close(); |
| } catch (SQLException e) { |
| log.warn("Cannot close connection to " + url, e); |
| } finally { |
| conn = null; |
| } |
| } |
| } |
| |
| private PreparedStatement closeStatement(PreparedStatement ps) { |
| if (ps != null) { |
| try { |
| ps.close(); |
| } catch (SQLException e) { |
| log.warn("Cannot close statement for " + url, e); |
| } |
| } |
| return null; |
| } |
| } |
| |
| private static class SinkOutputStream extends OutputStream { |
| private final PrimitiveSink sink; |
| |
| SinkOutputStream(PrimitiveSink sink) { |
| this.sink = sink; |
| } |
| |
| @Override |
| public void write(int b) { |
| sink.putByte((byte) b); |
| } |
| |
| @Override |
| public void write(byte[] b, int p, int n) { |
| sink.putBytes(b, p, n); |
| } |
| } |
| } |