com.google.errorprone.bugpatterns.threadsafety.AbstractLockMethodChecker.java Source code

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Here is the source code for com.google.errorprone.bugpatterns.threadsafety.AbstractLockMethodChecker.java

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/*
 * Copyright 2014 Google Inc. All Rights Reserved.
 *
 * 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.threadsafety;

import com.google.common.base.Functions;
import com.google.common.base.Joiner;
import com.google.common.base.Optional;
import com.google.common.collect.FluentIterable;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableSet;
import com.google.common.collect.Ordering;
import com.google.common.collect.Sets;
import com.google.common.collect.Sets.SetView;
import com.google.errorprone.VisitorState;
import com.google.errorprone.bugpatterns.BugChecker;
import com.google.errorprone.matchers.Description;
import com.sun.source.tree.MethodTree;
import com.sun.source.tree.Tree;
import java.util.List;
import java.util.Set;

/**
 * Abstract implementation of checkers for {@code @LockMethod} and{@code @UnlockMethod}.
 *
 * @author cushon@google.com (Liam Miller-Cushon)
 */
public abstract class AbstractLockMethodChecker extends BugChecker implements BugChecker.MethodTreeMatcher {

    /**
     * Returns the lock expressions in the {@code @LockMethod}/{@code @UnlockMethod}
     * annotation, if any.
     */
    protected abstract ImmutableList<String> getLockExpressions(MethodTree tree);

    /**
     * Searches the method body for locks that are acquired/released.
     */
    protected abstract Set<GuardedByExpression> getActual(MethodTree tree, VisitorState state);

    /**
     * Searches the method body for the incorrect lock operation (e.g. releasing a lock in
     * {@code @LockMethod}, or acquiring a lock in {@code @UnlockMethod}).
     */
    protected abstract Set<GuardedByExpression> getUnwanted(MethodTree tree, VisitorState state);

    /**
     * Builds the error message, given the list of locks that were not handled.
     */
    protected abstract String buildMessage(String unhandled);

    @Override
    public Description matchMethod(MethodTree tree, final VisitorState state) {

        ImmutableList<String> lockExpressions = getLockExpressions(tree);
        if (lockExpressions.isEmpty()) {
            return Description.NO_MATCH;
        }

        Optional<ImmutableSet<GuardedByExpression>> expected = parseLockExpressions(lockExpressions, tree, state);
        if (!expected.isPresent()) {
            return buildDescription(tree).setMessage("Could not resolve lock expression.").build();
        }

        Set<GuardedByExpression> unwanted = getUnwanted(tree, state);
        SetView<GuardedByExpression> mishandled = Sets.intersection(expected.get(), unwanted);
        if (!mishandled.isEmpty()) {
            String message = buildMessage(formatLockString(mishandled));
            return buildDescription(tree).setMessage(message).build();
        }

        Set<GuardedByExpression> actual = getActual(tree, state);
        SetView<GuardedByExpression> unhandled = Sets.difference(expected.get(), actual);
        if (!unhandled.isEmpty()) {
            String message = buildMessage(formatLockString(unhandled));
            return buildDescription(tree).setMessage(message).build();
        }

        return Description.NO_MATCH;
    }

    private static String formatLockString(Set<GuardedByExpression> locks) {
        ImmutableList<String> sortedUnhandled = FluentIterable.from(locks).transform(Functions.toStringFunction())
                .toSortedList(Ordering.natural());
        return Joiner.on(", ").join(sortedUnhandled);
    }

    private static Optional<ImmutableSet<GuardedByExpression>> parseLockExpressions(List<String> lockExpressions,
            Tree tree, VisitorState state) {
        ImmutableSet.Builder<GuardedByExpression> builder = ImmutableSet.builder();
        for (String lockExpression : lockExpressions) {
            Optional<GuardedByExpression> guard = GuardedByBinder.bindString(lockExpression,
                    GuardedBySymbolResolver.from(tree, state));
            if (!guard.isPresent()) {
                return Optional.absent();
            }
            builder.add(guard.get());
        }
        return Optional.of(builder.build());
    }
}