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/*******************************************************************************
 *     ___                  _   ____  ____
 *    / _ \ _   _  ___  ___| |_|  _ \| __ )
 *   | | | | | | |/ _ \/ __| __| | | |  _ \
 *   | |_| | |_| |  __/\__ \ |_| |_| | |_) |
 *    \__\_\\__,_|\___||___/\__|____/|____/
 *
 *  Copyright (c) 2014-2019 Appsicle
 *  Copyright (c) 2019-2020 QuestDB
 *
 *  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 io.questdb.cairo;

import io.questdb.log.Log;
import io.questdb.log.LogFactory;
import io.questdb.std.Files;
import io.questdb.std.FilesFacade;
import io.questdb.std.str.LPSZ;

public class ReadWriteMemory extends VirtualMemory {
    private static final Log LOG = LogFactory.getLog(ReadWriteMemory.class);
    private FilesFacade ff;
    private long fd = -1;

    public ReadWriteMemory(FilesFacade ff, LPSZ name, long maxPageSize) {
        of(ff, name, maxPageSize);
    }

    public ReadWriteMemory() {
    }

    @Override
    public void close() {
        long size = getAppendOffset();
        super.close();
        if (isOpen()) {
            try {
                AppendMemory.bestEffortClose(ff, LOG, fd, true, size, getMapPageSize());
            } finally {
                fd = -1;
            }
        }
    }

    @Override
    protected long allocateNextPage(int page) {
        long address;
        long offset = pageOffset(page);
        final long pageSize = getMapPageSize();

        if (ff.length(fd) < offset + pageSize) {
            ff.truncate(fd, offset + pageSize);
        }

        address = ff.mmap(fd, pageSize, offset, Files.MAP_RW);

        if (address == -1) {
            throw CairoException.instance(ff.errno()).put("Cannot mmap read-write fd=").put(fd).put(", offset=").put(offset).put(", size=").put(pageSize);
        }
        return address;
    }

    @Override
    protected long getPageAddress(int page) {
        return mapWritePage(page);
    }

    @Override
    protected void release(int page, long address) {
        ff.munmap(address, getPageSize(page));
    }

    public long getFd() {
        return fd;
    }

    public boolean isOpen() {
        return fd != -1;
    }

    public final void of(FilesFacade ff, LPSZ name, long pageSize) {
        close();
        this.ff = ff;
        fd = ff.openRW(name);
        if (fd == -1) {
            throw CairoException.instance(ff.errno()).put("Cannot open file: ").put(name);
        }
        long size = ff.length(fd);
        setPageSize(pageSize);
        ensurePagesListCapacity(size);
        LOG.info().$("open ").$(name).$(" [fd=").$(fd).$(']').$();
        try {
            // we may not be able to map page here
            // make sure we close file before bailing out
            jumpTo(size);
        } catch (CairoException e) {
            ff.close(fd);
            fd = -1;
            throw e;
        }
    }
}