Abort request when too many Druid filters are generated

CHANGELOG.md

@@ -15,6 +15,10 @@ pull request if there was one.
 
 ### Changed:
 
+- [Abort request when too many Druid filters are generated](https://github.com/yahoo/fili/pull/690)
+    * In order to avoid Druid queries with too much filters on high-cardinality dimension, Fili sets a upper limit
+      on the number of filters and aborts requests if the limit is exceeded.
+
 - [Class re-organization](https://github.com/yahoo/fili/pull/694)
     * Put `Granularity` interfaces and its implementations in the same package
     * Put `*ApiRequest` interfaces and their implementations in the same package

fili-core/src/main/java/com/yahoo/bard/webservice/data/filterbuilders/ConjunctionDruidFilterBuilder.java

@@ -2,6 +2,10 @@
 // Licensed under the terms of the Apache license. Please see LICENSE.md file distributed with this work for terms.
 package com.yahoo.bard.webservice.data.filterbuilders;
 
+import static com.yahoo.bard.webservice.web.ErrorMessageFormat.TOO_MANY_DRUID_FILTERS;
+
+import com.yahoo.bard.webservice.config.SystemConfig;
+import com.yahoo.bard.webservice.config.SystemConfigProvider;
 import com.yahoo.bard.webservice.data.dimension.Dimension;
 import com.yahoo.bard.webservice.data.dimension.DimensionRow;
 import com.yahoo.bard.webservice.data.dimension.DimensionRowNotFoundException;
@@ -11,6 +15,7 @@
 import com.yahoo.bard.webservice.druid.model.filter.ExtractionFilter;
 import com.yahoo.bard.webservice.druid.model.filter.Filter;
 import com.yahoo.bard.webservice.druid.model.filter.SelectorFilter;
+import com.yahoo.bard.webservice.exception.TooManyDruidFiltersException;
 import com.yahoo.bard.webservice.web.ApiFilter;
 import com.yahoo.bard.webservice.web.ErrorMessageFormat;
 
@@ -30,7 +35,15 @@
  * each dimension being filtered on.
  */
 public abstract class ConjunctionDruidFilterBuilder implements DruidFilterBuilder {
+
     private static final Logger LOG = LoggerFactory.getLogger(ConjunctionDruidFilterBuilder.class);
+    private static final SystemConfig SYSTEM_CONFIG = SystemConfigProvider.getInstance();
+
+    private static final int DEFAULT_MAX_NUM_DRUID_FILTERS = 10000;
+    private static final int MAX_NUM_DRUID_FILTERS = SYSTEM_CONFIG.getIntProperty(
+            SYSTEM_CONFIG.getPackageVariableName("max_num_druid_filters"),
+            DEFAULT_MAX_NUM_DRUID_FILTERS
+    );
 
     @Override
     public Filter buildFilters(Map<Dimension, Set<ApiFilter>> filterMap) throws DimensionRowNotFoundException {
@@ -52,6 +65,12 @@ public Filter buildFilters(Map<Dimension, Set<ApiFilter>> filterMap) throws Dime
         }
 
         AndFilter newFilter = new AndFilter(dimensionFilters);
+
+        if (newFilter.getFields().size() > MAX_NUM_DRUID_FILTERS) {
+            LOG.error(TOO_MANY_DRUID_FILTERS.logFormat());
+            throw new TooManyDruidFiltersException(TOO_MANY_DRUID_FILTERS.format());
+        }
+
         LOG.trace("Filter: {}", newFilter);
         return newFilter;
     }
@@ -88,6 +107,7 @@ protected Set<DimensionRow> getFilteredDimensionRows(Dimension dimension, Set<Ap
             LOG.debug(msg);
             throw new DimensionRowNotFoundException(msg);
         }
+
         return rows;
     }
 

fili-core/src/main/java/com/yahoo/bard/webservice/exception/TooManyDruidFiltersException.java

@@ -0,0 +1,43 @@
+// Copyright 2016 Yahoo Inc.
+// Licensed under the terms of the Apache license. Please see LICENSE.md file distributed with this work for terms.
+package com.yahoo.bard.webservice.exception;
+
+/**
+ * Unchecked exception for situations when too many Druid filters a generated for a Druid query.
+ * <p>
+ * Dimensions with extremely large cardinalities could result in such error when user put a "contain" filter on the
+ * dimension value. For example, a filter of dimension|id-contains[123], where there are 10,000 ID's starting with 123,
+ * could generate 10,000 Druid filters using
+ * {@link com.yahoo.bard.webservice.data.filterbuilders.DefaultDruidFilterBuilder}. This giant query shall eventually
+ * timeout the Druid query and returns the timeout error to API user.
+ */
+public class TooManyDruidFiltersException extends RuntimeException {
+
+    /**
+     * Constructor.
+     *
+     * @param message  Message of the exception
+     */
+    public TooManyDruidFiltersException(String message) {
+        super(message);
+    }
+
+    /**
+     * Constructor.
+     *
+     * @param cause  Cause of the exception
+     */
+    public TooManyDruidFiltersException(Throwable cause) {
+        super(cause);
+    }
+
+    /**
+     * Constructor.
+     *
+     * @param message  Message of the exception
+     * @param cause  Cause of the exception
+     */
+    public TooManyDruidFiltersException(String message, Throwable cause) {
+        super(message, cause);
+    }
+}

fili-core/src/main/java/com/yahoo/bard/webservice/web/ErrorMessageFormat.java

@@ -259,6 +259,12 @@ public enum ErrorMessageFormat implements MessageFormatter {
                                               "%s operator needs %d parameters but found %d"),
     HAVING_OPERATOR_IMPROPER_RANGE("Upper range cannot be less than the lower range for %s operator."),
 
+    TOO_MANY_DRUID_FILTERS(
+            "Too many filtering dimension values found. Request is aborted because it will significantly slows down " +
+                    "or timeout Druid query.",
+            "DruidFilterBuilder generated too many filters. Request is aborted."
+    ),
+
     UNABLE_TO_CREATE_DIR("Unable to create directory %s."),
     UNABLE_TO_DELETE_DIR("Unable to delete directory %s."),
     FAIL_TO_WIPTE_LUCENE_INDEX_DIR("Failed to wipte Lucene index at directory: %s"),

fili-core/src/main/resources/moduleConfig.properties

@@ -81,6 +81,9 @@ bard__lucene_index_path = [SET ME IN APPLICATION CONFIG]
 # Lucene search timeout in milliseconds
 bard__lucene_search_timeout_ms = 600000
 
+# Maximum number of druid filters in a Fili-generated Druid query
+bard__max_num_druid_filters = 10000
+
 # setting for maximum allowed results without any filters - used for /dim/values endpoint
 bard__max_results_without_filters = 10000
 

fili-core/src/test/resources/testApplicationConfig.properties

@@ -74,6 +74,9 @@ bard__cache_partial_data = false
 # Lucene index files path
 bard__lucene_index_path = ./target/tmp/
 
+# Maximum number of druid filters in a Fili-generated Druid query
+bard__max_num_druid_filters = 10000
+
 # max results without filters
 # Default number of records per-page. This applies ONLY to the dimensions endpoint, NOT to the data endpoint. The
 # data endpoint does not paginate by default.