com.google.gerrit.server.project.ProjectHierarchyIterator.java Source code

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Here is the source code for com.google.gerrit.server.project.ProjectHierarchyIterator.java

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// Copyright (C) 2013 The Android Open Source Project
//
// 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.gerrit.server.project;

import com.google.common.base.Joiner;
import com.google.common.collect.Lists;
import com.google.common.collect.Sets;
import com.google.gerrit.reviewdb.client.Project;
import com.google.gerrit.server.config.AllProjectsName;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.util.Iterator;
import java.util.List;
import java.util.NoSuchElementException;
import java.util.Set;

/**
 * Iterates from a project up through its parents to All-Projects.
 * <p>
 * If a cycle is detected the cycle is broken and All-Projects is visited.
 */
class ProjectHierarchyIterator implements Iterator<ProjectState> {
    private static final Logger log = LoggerFactory.getLogger(ProjectHierarchyIterator.class);

    private final ProjectCache cache;
    private final AllProjectsName allProjectsName;
    private final Set<Project.NameKey> seen;
    private ProjectState next;

    ProjectHierarchyIterator(ProjectCache c, AllProjectsName all, ProjectState firstResult) {
        cache = c;
        allProjectsName = all;

        seen = Sets.newLinkedHashSet();
        seen.add(firstResult.getProject().getNameKey());
        next = firstResult;
    }

    @Override
    public boolean hasNext() {
        return next != null;
    }

    @Override
    public ProjectState next() {
        ProjectState n = next;
        if (n == null) {
            throw new NoSuchElementException();
        }
        next = computeNext(n);
        return n;
    }

    private ProjectState computeNext(ProjectState n) {
        Project.NameKey parentName = n.getProject().getParent();
        if (parentName != null && visit(parentName)) {
            ProjectState p = cache.get(parentName);
            if (p != null) {
                return p;
            }
        }

        // Parent does not exist or was already visited.
        // Fall back to visit All-Projects exactly once.
        if (seen.add(allProjectsName)) {
            return cache.get(allProjectsName);
        }
        return null;
    }

    private boolean visit(Project.NameKey parentName) {
        if (seen.add(parentName)) {
            return true;
        }

        List<String> order = Lists.newArrayListWithCapacity(seen.size() + 1);
        for (Project.NameKey p : seen) {
            order.add(p.get());
        }
        int idx = order.lastIndexOf(parentName.get());
        order.add(parentName.get());
        log.warn("Cycle detected in projects: " + Joiner.on(" -> ").join(order.subList(idx, order.size())));
        return false;
    }

    @Override
    public void remove() {
        throw new UnsupportedOperationException();
    }
}