josh-mckenzie commented on a change in pull request #1213: URL: https://github.com/apache/cassandra/pull/1213#discussion_r734655938
########## File path: src/java/org/apache/cassandra/schema/PartitionDenylist.java ########## @@ -0,0 +1,517 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one + * or more contributor license agreements. See the NOTICE file + * distributed with this work for additional information + * regarding copyright ownership. The ASF licenses this file + * to you 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 org.apache.cassandra.schema; + +import java.nio.ByteBuffer; +import java.util.Collections; +import java.util.HashMap; +import java.util.HashSet; +import java.util.Map; +import java.util.NavigableSet; +import java.util.Set; +import java.util.TreeSet; +import java.util.concurrent.ExecutorService; +import java.util.concurrent.TimeUnit; + +import com.google.common.collect.ImmutableSet; +import com.google.common.collect.ImmutableSortedSet; +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +import com.github.benmanes.caffeine.cache.CacheLoader; +import com.github.benmanes.caffeine.cache.Caffeine; +import com.github.benmanes.caffeine.cache.LoadingCache; +import org.apache.cassandra.concurrent.ScheduledExecutors; +import org.apache.cassandra.config.DatabaseDescriptor; +import org.apache.cassandra.cql3.UntypedResultSet; +import org.apache.cassandra.db.PartitionPosition; +import org.apache.cassandra.dht.AbstractBounds; +import org.apache.cassandra.dht.Token; +import org.apache.cassandra.exceptions.RequestExecutionException; +import org.apache.cassandra.service.StorageService; +import org.apache.cassandra.service.reads.range.RangeCommands; +import org.apache.cassandra.utils.ByteBufferUtil; +import org.apache.cassandra.utils.NoSpamLogger; + +import static org.apache.cassandra.concurrent.ExecutorFactory.Global.executorFactory; +import static org.apache.cassandra.cql3.QueryProcessor.process; +import static org.apache.cassandra.utils.Clock.Global.currentTimeMillis; + +/** + * PartitionDenylist uses the system_distributed.partition_denylist table to maintain a list of denylisted partition keys + * for each keyspace/table. + * + * Keys can be entered manually into the partition_denylist table or via the JMX operation StorageProxyMBean.denylistKey + * + * The denylist is stored as one CQL partition per table, and the denylisted keys are column names in that partition. The denylisted + * keys for each table are cached in memory, and reloaded from the partition_denylist table every 24 hours (default) or when the + * StorageProxyMBean.loadPartitionDenylist is called via JMX. + * + * Concurrency of the cache is provided by the concurrency semantics of the guava LoadingCache. All values (DenylistEntry) are + * immutable collections of keys/tokens which are replaced in whole when the cache refreshes from disk. + * + * The intersection of the denylist and the configurable (though not conveniently exposed) ConsistencyLevel is subtle; essentially + * we prioritize operator flexibility in the face of degraded cluster state over the consistency of the denylist cache across + * the cluster. What this means in effect is that we warn when we have a degraded availability scenario rather than freezing + * the state of the denylist or, worse, presenting an empty denylist for the owned ks/table set. + * + * For example, in a scenario where you have RF=3 with 2 nodes down, a CL.QUORUM required CL for your denylist would mean + * you could effectively not change the denylist configuration for your only available node until you recovered one of the + * other nodes in this replica set owning the denylist data. Rather than forcing operators to change the CL of their denylist + * table, revise the denylist, reload the cache, then revert the CL, we instead allow all non-timer instigated reloads to proceed. + * + * On a cache refresh in which the cache entry for a denylist entry expires we do not continue with the reload of the + * cache value and instead use the expired value, warning to the user that their cache state is likely stale. + * + * Notably, in the current design it's possible for a table *cache expiration instigated* reload to end up violating the + * contract on total denylisted keys allowed in the case where it initially loads with a value less than the DBD + * allowable max per table limit due to global constraint enforcement on initial load. Our load and reload function + * simply enforce the *per table* limit without consideration to what that entails at the global key level. While we + * could track the constrained state and count in DenylistEntry, for now the complexity doesn't seem to justify the + * protection against that edge case. The enforcement should take place on a user-instigated full reload as well as + * error messaging about count violations, so this only applies to situations in which someone adds a key and doesn't + * actively tell the cache to fully reload to take that key into consideration, which one could reasonably expect to be + * an antipattern. + */ +public class PartitionDenylist +{ + private static final Logger logger = LoggerFactory.getLogger(PartitionDenylist.class); + private static final NoSpamLogger AVAILABILITY_LOGGER = NoSpamLogger.getLogger(logger, 1, TimeUnit.MINUTES); + + private final ExecutorService executor = executorFactory().pooled("DenylistCache", 2); + + /** We effectively don't use our initial empty cache to denylist until the {@link #load()} call which will replace it */ + private volatile LoadingCache<TableId, DenylistEntry> denylist = buildEmptyCache(); + + /** Denylist entry is never mutated once constructed, only replaced with a new entry when the cache is refreshed */ + private static class DenylistEntry + { + public final ImmutableSet<ByteBuffer> keys; + public final ImmutableSortedSet<Token> tokens; + + public DenylistEntry() + { + keys = ImmutableSet.of(); + tokens = ImmutableSortedSet.of(); + } + + public DenylistEntry(final ImmutableSet<ByteBuffer> keys, final ImmutableSortedSet<Token> tokens) + { + this.keys = keys; + this.tokens = tokens; + } + } + + // synchronized on this + private int loadAttempts = 0; + private int loadSuccesses = 0; + + public synchronized int getLoadAttempts() + { + return loadAttempts; + } + public synchronized int getLoadSuccesses() + { + return loadSuccesses; + } + + /** + * Performs initial load of the partition denylist. Should be called at startup and only loads if the operation + * is expected to succeed. If it is not possible to load at call time, a timer is set to retry. + */ + public void initialLoad() + { + if (!DatabaseDescriptor.getEnablePartitionDenylist()) + return; + + synchronized (this) + { + loadAttempts++; + } + + // Check if there are sufficient nodes to attempt reading all the denylist partitions before issuing the query. + // The pre-check prevents definite range-slice unavailables being marked and triggering an alert. Nodes may still change + // state between the check and the query, but it should significantly reduce the alert volume. + String retryReason = "Insufficient nodes"; + try + { + checkDenylistNodeAvailability(); + if (load()) + return; + } + catch (Throwable tr) + { + logger.error("Failed to load partition denylist", tr); + retryReason = "Exception"; + } + + // This path will also be taken on other failures other than UnavailableException, + // but seems like a good idea to retry anyway. + int retryInSeconds = DatabaseDescriptor.getDenylistInitialLoadRetrySeconds(); + logger.info("{} while loading partition denylist cache. Scheduled retry in {} seconds.", retryReason, retryInSeconds); + ScheduledExecutors.optionalTasks.schedule(this::initialLoad, retryInSeconds, TimeUnit.SECONDS); + } + + private boolean checkDenylistNodeAvailability() + { + boolean sufficientNodes = RangeCommands.sufficientLiveNodesForSelectStar(SystemDistributedKeyspace.PartitionDenylistTable, + DatabaseDescriptor.getDenylistConsistencyLevel()); + if (!sufficientNodes) + { + AVAILABILITY_LOGGER.warn("Attempting to load denylist and not enough nodes are available for a {} refresh. Reload the denylist when unavailable nodes are recovered to ensure your denylist remains in sync.", + DatabaseDescriptor.getDenylistConsistencyLevel()); + } + return sufficientNodes; + } + + /** Helper method as we need to both build cache on initial init but also on reload of cache contents and params */ + private LoadingCache<TableId, DenylistEntry> buildEmptyCache() + { + // We rely on details of .refreshAfterWrite to reload this async in the background when it's hit: + // https://github.com/ben-manes/caffeine/wiki/Refresh + return Caffeine.newBuilder() + .refreshAfterWrite(DatabaseDescriptor.getDenylistRefreshSeconds(), TimeUnit.SECONDS) + .executor(executor) + .build(new CacheLoader<TableId, DenylistEntry>() + { + @Override + public DenylistEntry load(final TableId tid) + { + // On initial load, we load whether or not the CL required count are available as the alternative + // is an empty denylist. This allows operators to intervene in the event they need to deny or + // undeny a specific partition key around a node recovery. + checkDenylistNodeAvailability(); + return getDenylistForTableFromCQL(tid); + } + + // The synchronous reload method defaults to being wrapped with a supplyAsync in CacheLoader.asyncReload + @Override + public DenylistEntry reload(final TableId tid, final DenylistEntry oldValue) + { + // Only process when we can hit the user specified CL for the denylist consistency on a timer prompted reload + if (checkDenylistNodeAvailability()) + { + final DenylistEntry newEntry = getDenylistForTableFromCQL(tid); + if (newEntry != null) + return newEntry; + } + if (oldValue != null) + return oldValue; + return new DenylistEntry(); + } + }); + } + + /** + * We need to fully rebuild a new cache to accommodate deleting items from the denylist and potentially shrinking + * the max allowable size in the list. We do not serve queries out of this denylist until it is populated + * so as not to introduce a window of having a partially filled cache allow denylisted entries. + */ + public boolean load() + { + final long start = currentTimeMillis(); + + final Map<TableId, DenylistEntry> allDenylists = getDenylistForAllTablesFromCQL(); + + // On initial load we have the slight overhead of GC'ing our initial empty cache + LoadingCache<TableId, DenylistEntry> newDenylist = buildEmptyCache(); + newDenylist.putAll(allDenylists); + + synchronized (this) + { + loadSuccesses++; + } + denylist = newDenylist; + logger.info("Loaded partition denylist cache in {}ms", currentTimeMillis() - start); + return true; + } + + /** + * We expect the caller to confirm that we are working with a valid keyspace and table. Further, we expect the usage + * pattern of this to be one-off key by key, not in a bulk process, so we relead the entire table's deny list entry + * on an addition or removal. + */ + public boolean addKeyToDenylist(final String keyspace, final String table, final ByteBuffer key) + { + if (!canDenylistKeyspace(keyspace)) + return false; + + final String insert = String.format("INSERT INTO system_distributed.partition_denylist (ks_name, table_name, key) VALUES ('%s', '%s', 0x%s)", + keyspace, table, ByteBufferUtil.bytesToHex(key)); + + try + { + process(insert, DatabaseDescriptor.getDenylistConsistencyLevel()); + return true; + } + catch (final RequestExecutionException e) + { + logger.error("Failed to denylist key [{}] in {}/{}", ByteBufferUtil.bytesToHex(key), keyspace, table, e); + } + return false; + } + + /** + * We expect the caller to confirm that we are working with a valid keyspace and table. + */ + public boolean removeKeyFromDenylist(final String keyspace, final String table, final ByteBuffer key) + { + final String delete = String.format("DELETE FROM system_distributed.partition_denylist " + + "WHERE ks_name = '%s' " + + "AND table_name = '%s' " + + "AND key = 0x%s", + keyspace, table, ByteBufferUtil.bytesToHex(key)); + + try + { + process(delete, DatabaseDescriptor.getDenylistConsistencyLevel()); + return true; + } + catch (final RequestExecutionException e) + { + logger.error("Failed to remove key from denylist: [{}] in {}/{}", ByteBufferUtil.bytesToHex(key), keyspace, table, e); + } + return false; + } + + /** + * We disallow denylisting partitions in certain critical keyspaces to prevent users from making their clusters + * inoperable. + */ + private boolean canDenylistKeyspace(final String keyspace) + { + return !SchemaConstants.DISTRIBUTED_KEYSPACE_NAME.equals(keyspace) && + !SchemaConstants.SYSTEM_KEYSPACE_NAME.equals(keyspace) && + !SchemaConstants.TRACE_KEYSPACE_NAME.equals(keyspace) && + !SchemaConstants.VIRTUAL_SCHEMA.equals(keyspace) && + !SchemaConstants.VIRTUAL_VIEWS.equals(keyspace) && + !SchemaConstants.AUTH_KEYSPACE_NAME.equals(keyspace); + } + + public boolean isKeyPermitted(final String keyspace, final String table, final ByteBuffer key) + { + return isKeyPermitted(getTableId(keyspace, table), key); + } + + public boolean isKeyPermitted(final TableId tid, final ByteBuffer key) + { + final TableMetadata tmd = Schema.instance.getTableMetadata(tid); + + // We have a few quick state checks to get out of the way first; this is hot path so we want to do these first if possible. + if (!DatabaseDescriptor.getEnablePartitionDenylist() || tid == null || !canDenylistKeyspace(tmd.keyspace)) + return true; + + try + { + // If we don't have an entry for this table id, nothing in it is denylisted. + DenylistEntry entry = denylist.get(tid); + if (entry == null) + return true; + return !entry.keys.contains(key); + } + catch (final Exception e) + { + // In the event of an error accessing or populating the cache, assume it's not denylisted + logAccessFailure(tmd, e); + return true; + } + } + + private void logAccessFailure(final TableMetadata tmd, Throwable e) + { + if (tmd == null) + logger.debug("Failed to access partition denylist cache for unknown table id {}", tmd.id, e); Review comment: Simple porting error on my part; originally logAccessFailure worked of the string TableId and looked up tmd for it. Cleared that up. There were a couple other spots where tmd could be null on retrieval I added into the Boolean logic to short-circuit things if so. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
