netudima commented on code in PR #4356: URL: https://github.com/apache/cassandra/pull/4356#discussion_r2348331916
########## src/java/org/apache/cassandra/db/virtual/ExceptionsTable.java: ########## @@ -0,0 +1,301 @@ +/* + * 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.db.virtual; + +import java.util.ArrayList; +import java.util.Collections; +import java.util.Date; +import java.util.Iterator; +import java.util.LinkedHashMap; +import java.util.List; +import java.util.Map; + +import com.google.common.annotations.VisibleForTesting; + +import org.apache.cassandra.db.DecoratedKey; +import org.apache.cassandra.db.marshal.Int32Type; +import org.apache.cassandra.db.marshal.ListType; +import org.apache.cassandra.db.marshal.TimestampType; +import org.apache.cassandra.db.marshal.UTF8Type; +import org.apache.cassandra.dht.LocalPartitioner; +import org.apache.cassandra.schema.TableMetadata; + +public class ExceptionsTable extends AbstractMutableVirtualTable +{ + public static final String EXCEPTIONS_TABLE_NAME = "uncaught_exceptions"; + public static final String EXCEPTION_CLASS_COLUMN_NAME = "exception_class"; + public static final String EXCEPTION_LOCATION_COLUMN_NAME = "exception_location"; + public static final String COUNT_COLUMN_NAME = "count"; + public static final String LAST_MESSAGE_COLUMN_NAME = "last_message"; + public static final String LAST_STACKTRACE_COLUMN_NAME = "last_stacktrace"; + public static final String LAST_OCCURENCE_COLUMN_NAME = "last_occurence"; + + /** + * Buffer of uncaught exceptions which happened while virtual table was not initialized. + */ + public static final List<ExceptionRow> preInitialisationBuffer = Collections.synchronizedList(new ArrayList<>()); + + // please be sure operations on this structure are thread-safe + @VisibleForTesting + final BoundedMap buffer; + + ExceptionsTable(String keyspace) + { + // for starters capped to 1k, I do not think we need to make this configurable (yet). + this(keyspace, 1000); + } + + ExceptionsTable(String keyspace, int maxSize) + { + super(TableMetadata.builder(keyspace, EXCEPTIONS_TABLE_NAME) + .comment("View into uncaught exceptions") + .kind(TableMetadata.Kind.VIRTUAL) + .partitioner(new LocalPartitioner(UTF8Type.instance)) + .addPartitionKeyColumn(EXCEPTION_CLASS_COLUMN_NAME, UTF8Type.instance) + .addClusteringColumn(EXCEPTION_LOCATION_COLUMN_NAME, UTF8Type.instance) + .addRegularColumn(COUNT_COLUMN_NAME, Int32Type.instance) + .addRegularColumn(LAST_MESSAGE_COLUMN_NAME, UTF8Type.instance) + .addRegularColumn(LAST_STACKTRACE_COLUMN_NAME, ListType.getInstance(UTF8Type.instance, false)) + .addRegularColumn(LAST_OCCURENCE_COLUMN_NAME, TimestampType.instance) + .build()); + + this.buffer = new BoundedMap(maxSize); + } + + /** + * @param exceptionClass exception class of uncaught exception + * @param exceptionLocation location where that exception was thrown + * @param message message of given exception + * @param stackTrace whole stacktrace of given exception + * @param occurenceTime time when given exception ocurred + */ + public void add(String exceptionClass, + String exceptionLocation, + String message, + List<String> stackTrace, + long occurenceTime) + { + synchronized (buffer) + { + ExceptionRow mergeInto = null; + + LinkedHashMap<String, ExceptionRow> exceptionRowWithLocation = buffer.get(exceptionClass); + + if (exceptionRowWithLocation != null) + { + ExceptionRow exceptionRow = exceptionRowWithLocation.get(exceptionLocation); + if (exceptionRow != null) + mergeInto = exceptionRow; + } + + if (mergeInto == null) + { + if (exceptionRowWithLocation == null) + { + // exception class and location can be null for value as we have it as part of keys already + LinkedHashMap<String, ExceptionRow> newLocation = new LinkedHashMap<>(); + newLocation.put(exceptionLocation, new ExceptionRow(null, null, 1, message, stackTrace, occurenceTime)); + buffer.put(exceptionClass, newLocation); + } + else + { + exceptionRowWithLocation.put(exceptionLocation, new ExceptionRow(null, null, 1, message, stackTrace, occurenceTime)); + // not important, can be null + // we need to do this, because if we add into a map which is + // a value of some buffer key, we might exceed the number + // of overall entries in the buffer + buffer.removeEldestEntry(null); + } + } + else + { + mergeInto.count += 1; + mergeInto.message = message; + mergeInto.stackTrace = stackTrace; + mergeInto.occurence = new Date(occurenceTime); + } + } + } + + public synchronized void flush() + { + for (ExceptionRow row : preInitialisationBuffer) + add(row.exceptionClass, row.exceptionLocation, row.message, row.stackTrace, row.occurence.getTime()); + + preInitialisationBuffer.clear(); + } + + @Override + public DataSet data() + { + SimpleDataSet result = new SimpleDataSet(metadata()); + + synchronized (buffer) + { + Iterator<Map.Entry<String, LinkedHashMap<String, ExceptionRow>>> iterator = buffer.entrySet().iterator(); + while (iterator.hasNext()) + { + Map.Entry<String, LinkedHashMap<String, ExceptionRow>> partition = iterator.next(); + for (Map.Entry<String, ExceptionRow> entry : partition.getValue().entrySet()) + populateRow(result, partition.getKey(), entry.getKey(), entry.getValue()); + } + } + + return result; + } + + @Override + public DataSet data(DecoratedKey partitionKey) + { + SimpleDataSet result = new SimpleDataSet(metadata()); + + synchronized (buffer) + { + String exceptionClass = UTF8Type.instance.getSerializer().deserialize(partitionKey.getKey()); + LinkedHashMap<String, ExceptionRow> partition = buffer.get(exceptionClass); + + if (partition != null) + { + for (Map.Entry<String, ExceptionRow> row : partition.entrySet()) + populateRow(result, exceptionClass, row.getKey(), row.getValue()); + } + } + + return result; + } + + private void populateRow(SimpleDataSet result, String exceptionClass, String exceptionLocation, ExceptionRow row) + { + result.row(exceptionClass, exceptionLocation) + .column(COUNT_COLUMN_NAME, row.count) + .column(LAST_MESSAGE_COLUMN_NAME, row.message) + .column(LAST_STACKTRACE_COLUMN_NAME, row.stackTrace) + .column(LAST_OCCURENCE_COLUMN_NAME, row.occurence); + } + + @Override + public void truncate() + { + synchronized (buffer) + { + buffer.clear(); + } + } + + public static class ExceptionRow + { + public String exceptionClass; Review Comment: it would be nice to mark immutable fields as final + we can use a lowest possible visibility scope (package private) -- This is an automated message from the Apache Git Service. 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