org.elasticsearch.script.expression.ExpressionScriptEngine Maven / Gradle / Ivy
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* http://www.apache.org/licenses/LICENSE-2.0
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package org.elasticsearch.script.expression;
import org.apache.lucene.expressions.Expression;
import org.apache.lucene.expressions.SimpleBindings;
import org.apache.lucene.expressions.js.JavascriptCompiler;
import org.apache.lucene.expressions.js.VariableContext;
import org.apache.lucene.index.LeafReaderContext;
import org.apache.lucene.queries.function.ValueSource;
import org.apache.lucene.queries.function.valuesource.DoubleConstValueSource;
import org.apache.lucene.search.Scorer;
import org.apache.lucene.search.SortField;
import org.elasticsearch.SpecialPermission;
import org.elasticsearch.common.Nullable;
import org.elasticsearch.index.fielddata.IndexFieldData;
import org.elasticsearch.index.fielddata.IndexNumericFieldData;
import org.elasticsearch.index.mapper.DateFieldMapper;
import org.elasticsearch.index.mapper.GeoPointFieldMapper.GeoPointFieldType;
import org.elasticsearch.index.mapper.MappedFieldType;
import org.elasticsearch.index.mapper.MapperService;
import org.elasticsearch.script.BucketAggregationScript;
import org.elasticsearch.script.BucketAggregationSelectorScript;
import org.elasticsearch.script.ClassPermission;
import org.elasticsearch.script.FilterScript;
import org.elasticsearch.script.ScoreScript;
import org.elasticsearch.script.ScriptContext;
import org.elasticsearch.script.ScriptEngine;
import org.elasticsearch.script.ScriptException;
import org.elasticsearch.script.SearchScript;
import org.elasticsearch.search.lookup.SearchLookup;
import java.io.IOException;
import java.security.AccessControlContext;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.text.ParseException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
/**
* Provides the infrastructure for Lucene expressions as a scripting language for Elasticsearch. Only
* {@link SearchScript}s are supported.
*/
public class ExpressionScriptEngine implements ScriptEngine {
public static final String NAME = "expression";
@Override
public String getType() {
return NAME;
}
@Override
public T compile(String scriptName, String scriptSource, ScriptContext context, Map params) {
// classloader created here
final SecurityManager sm = System.getSecurityManager();
SpecialPermission.check();
Expression expr = AccessController.doPrivileged(new PrivilegedAction() {
@Override
public Expression run() {
try {
// snapshot our context here, we check on behalf of the expression
AccessControlContext engineContext = AccessController.getContext();
ClassLoader loader = getClass().getClassLoader();
if (sm != null) {
loader = new ClassLoader(loader) {
@Override
protected Class loadClass(String name, boolean resolve) throws ClassNotFoundException {
try {
engineContext.checkPermission(new ClassPermission(name));
} catch (SecurityException e) {
throw new ClassNotFoundException(name, e);
}
return super.loadClass(name, resolve);
}
};
}
// NOTE: validation is delayed to allow runtime vars, and we don't have access to per index stuff here
return JavascriptCompiler.compile(scriptSource, JavascriptCompiler.DEFAULT_FUNCTIONS, loader);
} catch (ParseException e) {
throw convertToScriptException("compile error", scriptSource, scriptSource, e);
}
}
});
if (context.instanceClazz.equals(SearchScript.class)) {
SearchScript.Factory factory = (p, lookup) -> newSearchScript(expr, lookup, p);
return context.factoryClazz.cast(factory);
} else if (context.instanceClazz.equals(BucketAggregationScript.class)) {
return context.factoryClazz.cast(newBucketAggregationScriptFactory(expr));
} else if (context.instanceClazz.equals(BucketAggregationSelectorScript.class)) {
BucketAggregationScript.Factory factory = newBucketAggregationScriptFactory(expr);
BucketAggregationSelectorScript.Factory wrappedFactory = parameters -> new BucketAggregationSelectorScript(parameters) {
@Override
public boolean execute() {
return factory.newInstance(getParams()).execute().doubleValue() == 1.0;
}
};
return context.factoryClazz.cast(wrappedFactory);
} else if (context.instanceClazz.equals(FilterScript.class)) {
FilterScript.Factory factory = (p, lookup) -> newFilterScript(expr, lookup, p);
return context.factoryClazz.cast(factory);
} else if (context.instanceClazz.equals(ScoreScript.class)) {
ScoreScript.Factory factory = (p, lookup) -> newScoreScript(expr, lookup, p);
return context.factoryClazz.cast(factory);
}
throw new IllegalArgumentException("expression engine does not know how to handle script context [" + context.name + "]");
}
private static BucketAggregationScript.Factory newBucketAggregationScriptFactory(Expression expr) {
return parameters -> {
ReplaceableConstDoubleValues[] functionValuesArray =
new ReplaceableConstDoubleValues[expr.variables.length];
Map functionValuesMap = new HashMap<>();
for (int i = 0; i < expr.variables.length; ++i) {
functionValuesArray[i] = new ReplaceableConstDoubleValues();
functionValuesMap.put(expr.variables[i], functionValuesArray[i]);
}
return new BucketAggregationScript(parameters) {
@Override
public Double execute() {
getParams().forEach((name, value) -> {
ReplaceableConstDoubleValues placeholder = functionValuesMap.get(name);
if (placeholder == null) {
throw new IllegalArgumentException("Error using " + expr + ". " +
"The variable [" + name + "] does not exist in the executable expressions script.");
} else if (value instanceof Number == false) {
throw new IllegalArgumentException("Error using " + expr + ". " +
"Executable expressions scripts can only process numbers." +
" The variable [" + name + "] is not a number.");
} else {
placeholder.setValue(((Number) value).doubleValue());
}
});
return expr.evaluate(functionValuesArray);
}
};
};
}
private SearchScript.LeafFactory newSearchScript(Expression expr, SearchLookup lookup, @Nullable Map vars) {
MapperService mapper = lookup.doc().mapperService();
// NOTE: if we need to do anything complicated with bindings in the future, we can just extend Bindings,
// instead of complicating SimpleBindings (which should stay simple)
SimpleBindings bindings = new SimpleBindings();
ReplaceableConstDoubleValueSource specialValue = null;
boolean needsScores = false;
for (String variable : expr.variables) {
try {
if (variable.equals("_score")) {
bindings.add(new SortField("_score", SortField.Type.SCORE));
needsScores = true;
} else if (variable.equals("_value")) {
specialValue = new ReplaceableConstDoubleValueSource();
bindings.add("_value", specialValue);
// noop: _value is special for aggregations, and is handled in ExpressionScriptBindings
// TODO: if some uses it in a scoring expression, they will get a nasty failure when evaluating...need a
// way to know this is for aggregations and so _value is ok to have...
} else if (vars != null && vars.containsKey(variable)) {
// TODO: document and/or error if vars contains _score?
// NOTE: by checking for the variable in vars first, it allows masking document fields with a global constant,
// but if we were to reverse it, we could provide a way to supply dynamic defaults for documents missing the field?
Object value = vars.get(variable);
if (value instanceof Number) {
bindings.add(variable, new DoubleConstValueSource(((Number) value).doubleValue()).asDoubleValuesSource());
} else {
throw new ParseException("Parameter [" + variable + "] must be a numeric type", 0);
}
} else {
String fieldname = null;
String methodname = null;
String variablename = "value"; // .value is the default for doc['field'], its optional.
boolean dateAccessor = false; // true if the variable is of type doc['field'].date.xxx
VariableContext[] parts = VariableContext.parse(variable);
if (parts[0].text.equals("doc") == false) {
throw new ParseException("Unknown variable [" + parts[0].text + "]", 0);
}
if (parts.length < 2 || parts[1].type != VariableContext.Type.STR_INDEX) {
throw new ParseException("Variable 'doc' must be used with a specific field like: doc['myfield']", 3);
} else {
fieldname = parts[1].text;
}
if (parts.length == 3) {
if (parts[2].type == VariableContext.Type.METHOD) {
methodname = parts[2].text;
} else if (parts[2].type == VariableContext.Type.MEMBER) {
variablename = parts[2].text;
} else {
throw new IllegalArgumentException("Only member variables or member methods may be accessed on a "
+ "field when not accessing the field directly");
}
}
if (parts.length > 3) {
// access to the .date "object" within the field
if (parts.length == 4 && ("date".equals(parts[2].text) || "getDate".equals(parts[2].text))) {
if (parts[3].type == VariableContext.Type.METHOD) {
methodname = parts[3].text;
dateAccessor = true;
} else if (parts[3].type == VariableContext.Type.MEMBER) {
variablename = parts[3].text;
dateAccessor = true;
}
}
if (!dateAccessor) {
throw new IllegalArgumentException("Variable [" + variable + "] does not follow an allowed format of "
+ "either doc['field'] or doc['field'].method()");
}
}
MappedFieldType fieldType = mapper.fullName(fieldname);
if (fieldType == null) {
throw new ParseException("Field [" + fieldname + "] does not exist in mappings", 5);
}
IndexFieldData fieldData = lookup.doc().getForField(fieldType);
// delegate valuesource creation based on field's type
// there are three types of "fields" to expressions, and each one has a different "api" of variables and methods.
final ValueSource valueSource;
if (fieldType instanceof GeoPointFieldType) {
// geo
if (methodname == null) {
valueSource = GeoField.getVariable(fieldData, fieldname, variablename);
} else {
valueSource = GeoField.getMethod(fieldData, fieldname, methodname);
}
} else if (fieldType instanceof DateFieldMapper.DateFieldType) {
if (dateAccessor) {
// date object
if (methodname == null) {
valueSource = DateObject.getVariable(fieldData, fieldname, variablename);
} else {
valueSource = DateObject.getMethod(fieldData, fieldname, methodname);
}
} else {
// date field itself
if (methodname == null) {
valueSource = DateField.getVariable(fieldData, fieldname, variablename);
} else {
valueSource = DateField.getMethod(fieldData, fieldname, methodname);
}
}
} else if (fieldData instanceof IndexNumericFieldData) {
// number
if (methodname == null) {
valueSource = NumericField.getVariable(fieldData, fieldname, variablename);
} else {
valueSource = NumericField.getMethod(fieldData, fieldname, methodname);
}
} else {
throw new ParseException("Field [" + fieldname + "] must be numeric, date, or geopoint", 5);
}
needsScores |= valueSource.getSortField(false).needsScores();
bindings.add(variable, valueSource.asDoubleValuesSource());
}
} catch (Exception e) {
// we defer "binding" of variables until here: give context for that variable
throw convertToScriptException("link error", expr.sourceText, variable, e);
}
}
return new ExpressionSearchScript(expr, bindings, specialValue, needsScores);
}
/**
* This is a hack for filter scripts, which must return booleans instead of doubles as expression do.
* See https://github.com/elastic/elasticsearch/issues/26429.
*/
private FilterScript.LeafFactory newFilterScript(Expression expr, SearchLookup lookup, @Nullable Map vars) {
SearchScript.LeafFactory searchLeafFactory = newSearchScript(expr, lookup, vars);
return ctx -> {
SearchScript script = searchLeafFactory.newInstance(ctx);
return new FilterScript(vars, lookup, ctx) {
@Override
public boolean execute() {
return script.runAsDouble() != 0.0;
}
@Override
public void setDocument(int docid) {
script.setDocument(docid);
}
};
};
}
private ScoreScript.LeafFactory newScoreScript(Expression expr, SearchLookup lookup, @Nullable Map vars) {
SearchScript.LeafFactory searchLeafFactory = newSearchScript(expr, lookup, vars);
return new ScoreScript.LeafFactory() {
@Override
public boolean needs_score() {
return searchLeafFactory.needs_score();
}
@Override
public ScoreScript newInstance(LeafReaderContext ctx) throws IOException {
SearchScript script = searchLeafFactory.newInstance(ctx);
return new ScoreScript(vars, lookup, ctx) {
@Override
public double execute() {
return script.runAsDouble();
}
@Override
public void setDocument(int docid) {
script.setDocument(docid);
}
@Override
public void setScorer(Scorer scorer) {
script.setScorer(scorer);
}
@Override
public double get_score() {
return script.getScore();
}
};
}
};
}
/**
* converts a ParseException at compile-time or link-time to a ScriptException
*/
private ScriptException convertToScriptException(String message, String source, String portion, Throwable cause) {
List stack = new ArrayList<>();
stack.add(portion);
StringBuilder pointer = new StringBuilder();
if (cause instanceof ParseException) {
int offset = ((ParseException) cause).getErrorOffset();
for (int i = 0; i < offset; i++) {
pointer.append(' ');
}
}
pointer.append("^---- HERE");
stack.add(pointer.toString());
throw new ScriptException(message, cause, stack, source, NAME);
}
}
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