BaseSearch.java

/*
 * Copyright (C) 2011, Google Inc. and others
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Distribution License v. 1.0 which is available at
 * https://www.eclipse.org/org/documents/edl-v10.php.
 *
 * SPDX-License-Identifier: BSD-3-Clause
 */

package org.eclipse.jgit.internal.storage.pack;

import static org.eclipse.jgit.lib.Constants.OBJ_BLOB;
import static org.eclipse.jgit.lib.Constants.OBJ_TREE;

import java.io.IOException;
import java.util.List;
import java.util.Set;

import org.eclipse.jgit.errors.IncorrectObjectTypeException;
import org.eclipse.jgit.errors.MissingObjectException;
import org.eclipse.jgit.lib.AnyObjectId;
import org.eclipse.jgit.lib.FileMode;
import org.eclipse.jgit.lib.MutableObjectId;
import org.eclipse.jgit.lib.ObjectId;
import org.eclipse.jgit.lib.ObjectIdOwnerMap;
import org.eclipse.jgit.lib.ObjectLoader;
import org.eclipse.jgit.lib.ObjectReader;
import org.eclipse.jgit.lib.ProgressMonitor;
import org.eclipse.jgit.revwalk.RevTree;
import org.eclipse.jgit.treewalk.CanonicalTreeParser;

class BaseSearch {
    private static final int M_BLOB = FileMode.REGULAR_FILE.getBits();

    private static final int M_TREE = FileMode.TREE.getBits();

    private final ProgressMonitor progress;

    private final ObjectReader reader;

    private final ObjectId[] baseTrees;

    private final ObjectIdOwnerMap<ObjectToPack> objectsMap;

    private final List<ObjectToPack> edgeObjects;

    private final IntSet alreadyProcessed;

    private final ObjectIdOwnerMap<TreeWithData> treeCache;

    private final CanonicalTreeParser parser;

    private final MutableObjectId idBuf;

    BaseSearch(ProgressMonitor countingMonitor, Set<RevTree> bases,
            ObjectIdOwnerMap<ObjectToPack> objects,
            List<ObjectToPack> edges, ObjectReader or) {
        progress = countingMonitor;
        reader = or;
        baseTrees = bases.toArray(new ObjectId[0]);
        objectsMap = objects;
        edgeObjects = edges;

        alreadyProcessed = new IntSet();
        treeCache = new ObjectIdOwnerMap<>();
        parser = new CanonicalTreeParser();
        idBuf = new MutableObjectId();
    }

    void addBase(int objectType, byte[] pathBuf, int pathLen, int pathHash)
            throws IOException {
        final int tailMode = modeForType(objectType);
        if (tailMode == 0)
            return;

        if (!alreadyProcessed.add(pathHash))
            return;

        if (pathLen == 0) {
            for (ObjectId root : baseTrees)
                add(root, OBJ_TREE, pathHash);
            return;
        }

        final int firstSlash = nextSlash(pathBuf, 0, pathLen);

        CHECK_BASE: for (ObjectId root : baseTrees) {
            int ptr = 0;
            int end = firstSlash;
            int mode = end != pathLen ? M_TREE : tailMode;

            parser.reset(readTree(root));
            while (!parser.eof()) {
                int cmp = parser.pathCompare(pathBuf, ptr, end, mode);

                if (cmp < 0) {
                    parser.next();
                    continue;
                }

                if (cmp > 0)
                    continue CHECK_BASE;

                if (end == pathLen) {
                    if (parser.getEntryFileMode().getObjectType() == objectType) {
                        idBuf.fromRaw(parser.idBuffer(), parser.idOffset());
                        add(idBuf, objectType, pathHash);
                    }
                    continue CHECK_BASE;
                }

                if (!FileMode.TREE.equals(parser.getEntryRawMode()))
                    continue CHECK_BASE;

                ptr = end + 1;
                end = nextSlash(pathBuf, ptr, pathLen);
                mode = end != pathLen ? M_TREE : tailMode;

                idBuf.fromRaw(parser.idBuffer(), parser.idOffset());
                parser.reset(readTree(idBuf));
            }
        }
    }

    private static int modeForType(int typeCode) {
        switch (typeCode) {
        case OBJ_TREE:
            return M_TREE;

        case OBJ_BLOB:
            return M_BLOB;

        default:
            return 0;
        }
    }

    private static int nextSlash(byte[] pathBuf, int ptr, int end) {
        while (ptr < end && pathBuf[ptr] != '/')
            ptr++;
        return ptr;
    }

    @SuppressWarnings("ReferenceEquality")
    private void add(AnyObjectId id, int objectType, int pathHash) {
        ObjectToPack obj = new ObjectToPack(id, objectType);
        obj.setEdge();
        obj.setPathHash(pathHash);

        if (objectsMap.addIfAbsent(obj) == obj) {
            edgeObjects.add(obj);
            progress.update(1);
        }
    }

    private byte[] readTree(AnyObjectId id) throws MissingObjectException,
            IncorrectObjectTypeException, IOException {
        TreeWithData tree = treeCache.get(id);
        if (tree != null)
            return tree.buf;

        ObjectLoader ldr = reader.open(id, OBJ_TREE);
        byte[] buf = ldr.getCachedBytes(Integer.MAX_VALUE);
        treeCache.add(new TreeWithData(id, buf));
        return buf;
    }

    private static class TreeWithData extends ObjectIdOwnerMap.Entry {
        final byte[] buf;

        TreeWithData(AnyObjectId id, byte[] buf) {
            super(id);
            this.buf = buf;
        }
    }
}