com.google.errorprone.bugpatterns.ThreadLocalUsage Maven / Gradle / Ivy
/*
* Copyright 2017 The Error Prone Authors.
*
* Licensed 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 com.google.errorprone.bugpatterns;
import static com.google.common.collect.Iterables.getOnlyElement;
import static com.google.errorprone.BugPattern.SeverityLevel.WARNING;
import static com.google.errorprone.matchers.Description.NO_MATCH;
import static com.google.errorprone.matchers.method.MethodMatchers.constructor;
import static com.google.errorprone.predicates.TypePredicates.isDescendantOf;
import static com.google.errorprone.util.ASTHelpers.getSymbol;
import static com.google.errorprone.util.ASTHelpers.getType;
import static com.google.errorprone.util.ASTHelpers.hasDirectAnnotationWithSimpleName;
import static com.google.errorprone.util.ASTHelpers.isSubtype;
import com.google.common.collect.ImmutableSet;
import com.google.common.collect.Streams;
import com.google.errorprone.BugPattern;
import com.google.errorprone.VisitorState;
import com.google.errorprone.bugpatterns.BugChecker.NewClassTreeMatcher;
import com.google.errorprone.matchers.Description;
import com.google.errorprone.matchers.Matcher;
import com.google.errorprone.suppliers.Supplier;
import com.sun.source.tree.ClassTree;
import com.sun.source.tree.ExpressionTree;
import com.sun.source.tree.NewClassTree;
import com.sun.source.tree.Tree;
import com.sun.source.tree.VariableTree;
import com.sun.tools.javac.code.Symbol;
import com.sun.tools.javac.code.Symbol.VarSymbol;
import com.sun.tools.javac.code.Type;
/** A {@link BugChecker}; see the associated {@link BugPattern} annotation for details. */
@BugPattern(summary = "ThreadLocals should be stored in static fields", severity = WARNING)
public class ThreadLocalUsage extends BugChecker implements NewClassTreeMatcher {
private static final Matcher NEW_THREAD_LOCAL =
constructor().forClass(isDescendantOf("java.lang.ThreadLocal"));
@Override
public Description matchNewClass(NewClassTree tree, VisitorState state) {
if (!NEW_THREAD_LOCAL.matches(tree, state)) {
return NO_MATCH;
}
if (wellKnownTypeArgument(tree, state)) {
return NO_MATCH;
}
Tree parent = state.getPath().getParentPath().getLeaf();
if (!(parent instanceof VariableTree)) {
// If the ThreadLocal is created outside of a field we can't easily make assumptions about its
// scope.
return NO_MATCH;
}
VarSymbol sym = getSymbol((VariableTree) parent);
if (sym.isStatic()) {
return NO_MATCH;
}
if (Streams.stream(state.getPath())
.filter(ClassTree.class::isInstance)
.map(ClassTree.class::cast)
.anyMatch(
c -> {
if (hasDirectAnnotationWithSimpleName(getSymbol(c), "Singleton")) {
return true;
}
Type scopeType = COM_GOOGLE_INJECT_SCOPE.get(state);
if (isSubtype(getType(c), scopeType, state)) {
return true;
}
return false;
})) {
// The instance X thread issue doesn't apply if there's only one instance.
return NO_MATCH;
}
return describeMatch(tree);
}
private static final ImmutableSet WELL_KNOWN_TYPES =
ImmutableSet.of(
"java.lang.String",
"java.lang.Boolean",
"java.lang.Long",
"java.lang.Integer",
"java.lang.Short",
"java.lang.Character",
"java.lang.Float",
"java.lang.Double");
/** Ignore some common ThreadLocal type arguments that are fine to have per-instance copies of. */
private static boolean wellKnownTypeArgument(NewClassTree tree, VisitorState state) {
Type type = getType(tree);
if (type == null) {
return false;
}
type = state.getTypes().asSuper(type, JAVA_LANG_THREADLOCAL.get(state));
if (type == null) {
return false;
}
if (type.getTypeArguments().isEmpty()) {
return false;
}
Type argType = getOnlyElement(type.getTypeArguments());
if (WELL_KNOWN_TYPES.contains(argType.asElement().getQualifiedName().toString())) {
return true;
}
if (isSubtype(argType, JAVA_TEXT_DATEFORMAT.get(state), state)) {
return true;
}
return false;
}
private static final Supplier JAVA_LANG_THREADLOCAL =
VisitorState.memoize(state -> state.getSymbolFromString("java.lang.ThreadLocal"));
private static final Supplier COM_GOOGLE_INJECT_SCOPE =
VisitorState.memoize(state -> state.getTypeFromString("com.google.inject.Scope"));
private static final Supplier JAVA_TEXT_DATEFORMAT =
VisitorState.memoize(state -> state.getTypeFromString("java.text.DateFormat"));
}