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HDDS-1802. Add Eviction policy for table cache. (#1100)

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This commit is contained in:
Bharat Viswanadham 2019-07-17 18:19:06 -07:00 committed by GitHub
parent 9792f58662
commit 73e6ffce69
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8 changed files with 305 additions and 48 deletions
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14
hadoop-hdds/common/src/main/java/org/apache/hadoop/utils/db/DBStore.java
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@ -25,6 +25,7 @@
import java.util.Map;
import org.apache.hadoop.classification.InterfaceStability;
import org.apache.hadoop.utils.db.cache.TableCacheImpl;
/**
* The DBStore interface provides the ability to create Tables, which store
@ -47,7 +48,9 @@ public interface DBStore extends AutoCloseable {
/**
* Gets an existing TableStore with implicit key/value conversion.
* Gets an existing TableStore with implicit key/value conversion and
* with default cleanup policy for cache. Default cache clean up policy is
* manual.
*
* @param name - Name of the TableStore to get
* @param keyType
@ -58,6 +61,15 @@ public interface DBStore extends AutoCloseable {
<KEY, VALUE> Table<KEY, VALUE> getTable(String name,
Class<KEY> keyType, Class<VALUE> valueType) throws IOException;
/**
* Gets an existing TableStore with implicit key/value conversion and
* with specified cleanup policy for cache.
* @throws IOException
*/
<KEY, VALUE> Table<KEY, VALUE> getTable(String name,
Class<KEY> keyType, Class<VALUE> valueType,
TableCacheImpl.CacheCleanupPolicy cleanupPolicy) throws IOException;
/**
* Lists the Known list of Tables in a DB.
*

9
hadoop-hdds/common/src/main/java/org/apache/hadoop/utils/db/RDBStore.java
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@ -38,6 +38,7 @@
import org.apache.hadoop.utils.RocksDBStoreMBean;
import com.google.common.base.Preconditions;
import org.apache.hadoop.utils.db.cache.TableCacheImpl;
import org.apache.ratis.thirdparty.com.google.common.annotations.VisibleForTesting;
import org.rocksdb.ColumnFamilyDescriptor;
import org.rocksdb.ColumnFamilyHandle;
@ -260,6 +261,14 @@ public <KEY, VALUE> Table<KEY, VALUE> getTable(String name,
valueType);
}
@Override
public <KEY, VALUE> Table<KEY, VALUE> getTable(String name,
Class<KEY> keyType, Class<VALUE> valueType,
TableCacheImpl.CacheCleanupPolicy cleanupPolicy) throws IOException {
return new TypedTable<KEY, VALUE>(getTable(name), codecRegistry, keyType,
valueType, cleanupPolicy);
}
@Override
public ArrayList<Table> listTables() throws IOException {
ArrayList<Table> returnList = new ArrayList<>();

86
hadoop-hdds/common/src/main/java/org/apache/hadoop/utils/db/TypedTable.java
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@ -23,11 +23,16 @@
import java.util.Map;
import com.google.common.annotations.VisibleForTesting;
import com.google.common.base.Optional;
import org.apache.hadoop.utils.db.cache.CacheKey;
import org.apache.hadoop.utils.db.cache.CacheResult;
import org.apache.hadoop.utils.db.cache.CacheValue;
import org.apache.hadoop.utils.db.cache.PartialTableCache;
import org.apache.hadoop.utils.db.cache.TableCacheImpl;
import org.apache.hadoop.utils.db.cache.TableCache;
import org.apache.hadoop.utils.db.cache.TableCacheImpl.CacheCleanupPolicy;
import static org.apache.hadoop.utils.db.cache.CacheResult.CacheStatus.EXISTS;
import static org.apache.hadoop.utils.db.cache.CacheResult.CacheStatus.NOT_EXIST;
/**
* Strongly typed table implementation.
* <p>
@ -49,16 +54,61 @@ public class TypedTable<KEY, VALUE> implements Table<KEY, VALUE> {
private final TableCache<CacheKey<KEY>, CacheValue<VALUE>> cache;
private final static long EPOCH_DEFAULT = -1L;
/**
* Create an TypedTable from the raw table.
* Default cleanup policy used for the table is
* {@link CacheCleanupPolicy#MANUAL}.
* @param rawTable
* @param codecRegistry
* @param keyType
* @param valueType
*/
public TypedTable(
Table<byte[], byte[]> rawTable,
CodecRegistry codecRegistry, Class<KEY> keyType,
Class<VALUE> valueType) {
Class<VALUE> valueType) throws IOException {
this(rawTable, codecRegistry, keyType, valueType,
CacheCleanupPolicy.MANUAL);
}
/**
* Create an TypedTable from the raw table with specified cleanup policy
* for table cache.
* @param rawTable
* @param codecRegistry
* @param keyType
* @param valueType
* @param cleanupPolicy
*/
public TypedTable(
Table<byte[], byte[]> rawTable,
CodecRegistry codecRegistry, Class<KEY> keyType,
Class<VALUE> valueType,
TableCacheImpl.CacheCleanupPolicy cleanupPolicy) throws IOException {
this.rawTable = rawTable;
this.codecRegistry = codecRegistry;
this.keyType = keyType;
this.valueType = valueType;
cache = new PartialTableCache<>();
cache = new TableCacheImpl<>(cleanupPolicy);
if (cleanupPolicy == CacheCleanupPolicy.NEVER) {
//fill cache
try(TableIterator<KEY, ? extends KeyValue<KEY, VALUE>> tableIterator =
iterator()) {
while (tableIterator.hasNext()) {
KeyValue< KEY, VALUE > kv = tableIterator.next();
// We should build cache after OM restart when clean up policy is
// NEVER. Setting epoch value -1, so that when it is marked for
// delete, this will be considered for cleanup.
cache.put(new CacheKey<>(kv.getKey()),
new CacheValue<>(Optional.of(kv.getValue()), EPOCH_DEFAULT));
}
}
}
}
@Override
@ -83,9 +133,17 @@ public boolean isEmpty() throws IOException {
@Override
public boolean isExist(KEY key) throws IOException {
CacheValue<VALUE> cacheValue= cache.get(new CacheKey<>(key));
return (cacheValue != null && cacheValue.getCacheValue() != null) ||
rawTable.isExist(codecRegistry.asRawData(key));
CacheResult<CacheValue<VALUE>> cacheResult =
cache.lookup(new CacheKey<>(key));
if (cacheResult.getCacheStatus() == EXISTS) {
return true;
} else if (cacheResult.getCacheStatus() == NOT_EXIST) {
return false;
} else {
return rawTable.isExist(codecRegistry.asRawData(key));
}
}
/**
@ -104,14 +162,16 @@ public boolean isExist(KEY key) throws IOException {
public VALUE get(KEY key) throws IOException {
// Here the metadata lock will guarantee that cache is not updated for same
// key during get key.
CacheValue< VALUE > cacheValue = cache.get(new CacheKey<>(key));
if (cacheValue == null) {
// If no cache for the table or if it does not exist in cache get from
// RocksDB table.
return getFromTable(key);
CacheResult<CacheValue<VALUE>> cacheResult =
cache.lookup(new CacheKey<>(key));
if (cacheResult.getCacheStatus() == EXISTS) {
return cacheResult.getValue().getCacheValue();
} else if (cacheResult.getCacheStatus() == NOT_EXIST) {
return null;
} else {
// We have a value in cache, return the value.
return cacheValue.getCacheValue();
return getFromTable(key);
}
}

58
hadoop-hdds/common/src/main/java/org/apache/hadoop/utils/db/cache/CacheResult.java vendored Normal file
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@ -0,0 +1,58 @@
package org.apache.hadoop.utils.db.cache;
import java.util.Objects;
/**
* CacheResult which is returned as response for Key exist in cache or not.
* @param <CACHEVALUE>
*/
public class CacheResult<CACHEVALUE extends CacheValue> {
private CacheStatus cacheStatus;
private CACHEVALUE cachevalue;
public CacheResult(CacheStatus cacheStatus, CACHEVALUE cachevalue) {
this.cacheStatus = cacheStatus;
this.cachevalue = cachevalue;
}
public CacheStatus getCacheStatus() {
return cacheStatus;
}
public CACHEVALUE getValue() {
return cachevalue;
}
@Override
public boolean equals(Object o) {
if (this == o) {
return true;
}
if (o == null || getClass() != o.getClass()) {
return false;
}
CacheResult< ? > that = (CacheResult< ? >) o;
return cacheStatus == that.cacheStatus &&
Objects.equals(cachevalue, that.cachevalue);
}
@Override
public int hashCode() {
return Objects.hash(cacheStatus, cachevalue);
}
/**
* Status which tells whether key exists in cache or not.
*/
public enum CacheStatus {
EXISTS, // When key exists in cache.
NOT_EXIST, // We guarantee that it does not exist. This will be returned
// when the key does not exist in cache, when cache clean up policy is
// NEVER.
MAY_EXIST // This will be returned when the key does not exist in
// cache, when cache clean up policy is MANUAL. So caller need to check
// if it might exist in it's rocksdb table.
}
}

31
hadoop-hdds/common/src/main/java/org/apache/hadoop/utils/db/cache/TableCache.java vendored
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@ -21,7 +21,8 @@
import org.apache.hadoop.classification.InterfaceAudience.Private;
import org.apache.hadoop.classification.InterfaceStability.Evolving;
import org.apache.hadoop.utils.db.cache.CacheResult.CacheStatus;
import org.apache.hadoop.utils.db.cache.TableCacheImpl.CacheCleanupPolicy;
import java.util.Iterator;
import java.util.Map;
@ -52,8 +53,11 @@ public interface TableCache<CACHEKEY extends CacheKey,
/**
* Removes all the entries from the cache which are having epoch value less
* than or equal to specified epoch value. For FullTable Cache this is a
* do-nothing operation.
* than or equal to specified epoch value.
*
* If clean up policy is NEVER, this is a do nothing operation.
* If clean up policy is MANUAL, it is caller responsibility to cleanup the
* cache before calling cleanup.
* @param epoch
*/
void cleanup(long epoch);
@ -69,4 +73,25 @@ public interface TableCache<CACHEKEY extends CacheKey,
* @return iterator of the underlying cache for the table.
*/
Iterator<Map.Entry<CACHEKEY, CACHEVALUE>> iterator();
/**
* Check key exist in cache or not.
*
* If it exists return CacheResult with value and status as
* {@link CacheStatus#EXISTS}
*
* If it does not exist:
* If cache clean up policy is
* {@link TableCacheImpl.CacheCleanupPolicy#NEVER} it means table cache is
* full cache. It return's {@link CacheResult} with null
* and status as {@link CacheStatus#NOT_EXIST}.
*
* If cache clean up policy is {@link CacheCleanupPolicy#MANUAL} it means
* table cache is partial cache. It return's {@link CacheResult} with
* null and status as MAY_EXIST.
*
* @param cachekey
*/
CacheResult<CACHEVALUE> lookup(CACHEKEY cachekey);
}

73
hadoop-hdds/common/src/main/java/org/apache/hadoop/utils/db/cache/PartialTableCache.java → hadoop-hdds/common/src/main/java/org/apache/hadoop/utils/db/cache/TableCacheImpl.java vendored
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@ -32,21 +32,28 @@
import org.apache.hadoop.classification.InterfaceStability.Evolving;
/**
* Cache implementation for the table, this cache is partial cache, this will
* be cleaned up, after entries are flushed to DB.
* Cache implementation for the table. Depending on the cache clean up policy
* this cache will be full cache or partial cache.
*
* If cache cleanup policy is set as {@link CacheCleanupPolicy#MANUAL},
* this will be a partial cache.
*
* If cache cleanup policy is set as {@link CacheCleanupPolicy#NEVER},
* this will be a full cache.
*/
@Private
@Evolving
public class PartialTableCache<CACHEKEY extends CacheKey,
public class TableCacheImpl<CACHEKEY extends CacheKey,
CACHEVALUE extends CacheValue> implements TableCache<CACHEKEY, CACHEVALUE> {
private final ConcurrentHashMap<CACHEKEY, CACHEVALUE> cache;
private final TreeSet<EpochEntry<CACHEKEY>> epochEntries;
private ExecutorService executorService;
private CacheCleanupPolicy cleanupPolicy;
public PartialTableCache() {
public TableCacheImpl(CacheCleanupPolicy cleanupPolicy) {
cache = new ConcurrentHashMap<>();
epochEntries = new TreeSet<>();
// Created a singleThreadExecutor, so one cleanup will be running at a
@ -54,7 +61,7 @@ public PartialTableCache() {
ThreadFactory build = new ThreadFactoryBuilder().setDaemon(true)
.setNameFormat("PartialTableCache Cleanup Thread - %d").build();
executorService = Executors.newSingleThreadExecutor(build);
this.cleanupPolicy = cleanupPolicy;
}
@Override
@ -70,7 +77,7 @@ public void put(CACHEKEY cacheKey, CACHEVALUE value) {
@Override
public void cleanup(long epoch) {
executorService.submit(() -> evictCache(epoch));
executorService.submit(() -> evictCache(epoch, cleanupPolicy));
}
@Override
@ -83,17 +90,25 @@ public Iterator<Map.Entry<CACHEKEY, CACHEVALUE>> iterator() {
return cache.entrySet().iterator();
}
private void evictCache(long epoch) {
private void evictCache(long epoch, CacheCleanupPolicy cacheCleanupPolicy) {
EpochEntry<CACHEKEY> currentEntry = null;
for (Iterator<EpochEntry<CACHEKEY>> iterator = epochEntries.iterator();
iterator.hasNext();) {
currentEntry = iterator.next();
CACHEKEY cachekey = currentEntry.getCachekey();
CacheValue cacheValue = cache.computeIfPresent(cachekey, ((k, v) -> {
if (cleanupPolicy == CacheCleanupPolicy.MANUAL) {
if (v.getEpoch() <= epoch) {
iterator.remove();
return null;
}
} else if (cleanupPolicy == CacheCleanupPolicy.NEVER) {
// Remove only entries which are marked for delete.
if (v.getEpoch() <= epoch && v.getCacheValue() == null) {
iterator.remove();
return null;
}
}
return v;
}));
// If currentEntry epoch is greater than epoch, we have deleted all
@ -103,4 +118,48 @@ private void evictCache(long epoch) {
}
}
}
public CacheResult<CACHEVALUE> lookup(CACHEKEY cachekey) {
// TODO: Remove this check once HA and Non-HA code is merged and all
// requests are converted to use cache and double buffer.
// This is to done as temporary instead of passing ratis enabled flag
// which requires more code changes. We cannot use ratis enabled flag
// also because some of the requests in OM HA are not modified to use
// double buffer and cache.
if (cache.size() == 0) {
return new CacheResult<>(CacheResult.CacheStatus.MAY_EXIST,
null);
}
CACHEVALUE cachevalue = cache.get(cachekey);
if (cachevalue == null) {
if (cleanupPolicy == CacheCleanupPolicy.NEVER) {
return new CacheResult<>(CacheResult.CacheStatus.NOT_EXIST, null);
} else {
return new CacheResult<>(CacheResult.CacheStatus.MAY_EXIST,
null);
}
} else {
if (cachevalue.getCacheValue() != null) {
return new CacheResult<>(CacheResult.CacheStatus.EXISTS, cachevalue);
} else {
// When entity is marked for delete, cacheValue will be set to null.
// In that case we can return NOT_EXIST irrespective of cache cleanup
// policy.
return new CacheResult<>(CacheResult.CacheStatus.NOT_EXIST, null);
}
}
}
/**
* Cleanup policies for table cache.
*/
public enum CacheCleanupPolicy {
NEVER, // Cache will not be cleaned up. This mean's the table maintains
// full cache.
MANUAL // Cache will be cleaned up, once after flushing to DB. It is
// caller's responsibility to flush to DB, before calling cleanup cache.
}
}

49
hadoop-hdds/common/src/test/java/org/apache/hadoop/utils/db/cache/TestPartialTableCache.java → hadoop-hdds/common/src/test/java/org/apache/hadoop/utils/db/cache/TestTableCacheImpl.java vendored
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@ -19,6 +19,8 @@
package org.apache.hadoop.utils.db.cache;
import java.util.Arrays;
import java.util.Collection;
import java.util.concurrent.CompletableFuture;
import com.google.common.base.Optional;
@ -26,18 +28,40 @@
import org.junit.Assert;
import org.junit.Before;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.junit.runners.Parameterized;
import static org.junit.Assert.fail;
/**
* Class tests partial table cache.
*/
public class TestPartialTableCache {
@RunWith(value = Parameterized.class)
public class TestTableCacheImpl {
private TableCache<CacheKey<String>, CacheValue<String>> tableCache;
private final TableCacheImpl.CacheCleanupPolicy cacheCleanupPolicy;
@Parameterized.Parameters
public static Collection<Object[]> policy() {
Object[][] params = new Object[][] {
{TableCacheImpl.CacheCleanupPolicy.NEVER},
{TableCacheImpl.CacheCleanupPolicy.MANUAL}
};
return Arrays.asList(params);
}
public TestTableCacheImpl(
TableCacheImpl.CacheCleanupPolicy cacheCleanupPolicy) {
this.cacheCleanupPolicy = cacheCleanupPolicy;
}
@Before
public void create() {
tableCache = new PartialTableCache<>();
tableCache =
new TableCacheImpl<>(cacheCleanupPolicy);
}
@Test
public void testPartialTableCache() {
@ -98,26 +122,27 @@ public void testPartialTableCacheParallel() throws Exception {
tableCache.get(new CacheKey<>(Integer.toString(i))).getCacheValue());
}
int deleted = 5;
// cleanup first 5 entires
tableCache.cleanup(deleted);
value = future.get();
Assert.assertEquals(10, value);
totalCount += value;
if (cacheCleanupPolicy == TableCacheImpl.CacheCleanupPolicy.MANUAL) {
int deleted = 5;
// cleanup first 5 entires
tableCache.cleanup(deleted);
// We should totalCount - deleted entries in cache.
final int tc = totalCount;
GenericTestUtils.waitFor(() -> (tc - deleted == tableCache.size()), 100,
5000);
// Check if we have remaining entries.
for (int i=6; i <= totalCount; i++) {
Assert.assertEquals(Integer.toString(i),
tableCache.get(new CacheKey<>(Integer.toString(i))).getCacheValue());
Assert.assertEquals(Integer.toString(i), tableCache.get(
new CacheKey<>(Integer.toString(i))).getCacheValue());
}
tableCache.cleanup(10);
tableCache.cleanup(totalCount);
@ -125,6 +150,12 @@ public void testPartialTableCacheParallel() throws Exception {
// Cleaned up all entries, so cache size should be zero.
GenericTestUtils.waitFor(() -> (0 == tableCache.size()), 100,
5000);
} else {
tableCache.cleanup(totalCount);
Assert.assertEquals(totalCount, tableCache.size());
}
}
private int writeToCache(int count, int startVal, long sleep)

7
hadoop-ozone/ozone-manager/src/main/java/org/apache/hadoop/ozone/om/OmMetadataManagerImpl.java
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@ -69,6 +69,7 @@
import org.apache.hadoop.utils.db.TypedTable;
import org.apache.hadoop.utils.db.cache.CacheKey;
import org.apache.hadoop.utils.db.cache.CacheValue;
import org.apache.hadoop.utils.db.cache.TableCacheImpl;
import org.eclipse.jetty.util.StringUtil;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
@ -269,11 +270,13 @@ protected void initializeOmTables() throws IOException {
this.store.getTable(USER_TABLE, String.class, VolumeList.class);
checkTableStatus(userTable, USER_TABLE);
volumeTable =
this.store.getTable(VOLUME_TABLE, String.class, OmVolumeArgs.class);
this.store.getTable(VOLUME_TABLE, String.class, OmVolumeArgs.class,
TableCacheImpl.CacheCleanupPolicy.NEVER);
checkTableStatus(volumeTable, VOLUME_TABLE);
bucketTable =
this.store.getTable(BUCKET_TABLE, String.class, OmBucketInfo.class);
this.store.getTable(BUCKET_TABLE, String.class, OmBucketInfo.class,
TableCacheImpl.CacheCleanupPolicy.NEVER);
checkTableStatus(bucketTable, BUCKET_TABLE);