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 *  Copyright (c) 2014-2019 Appsicle
 *  Copyright (c) 2019-2023 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
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package io.questdb.cairo.vm;

import io.questdb.cairo.CairoConfiguration;
import io.questdb.cairo.CairoException;
import io.questdb.cairo.TableUtils;
import io.questdb.cairo.vm.api.MemoryCMR;
import io.questdb.log.Log;
import io.questdb.log.LogFactory;
import io.questdb.std.Files;
import io.questdb.std.FilesFacade;
import io.questdb.std.MemoryTag;
import io.questdb.std.str.LPSZ;

import static io.questdb.cairo.vm.Vm.PARANOIA_MODE;

//contiguous mapped readable 
public class MemoryCMRImpl extends AbstractMemoryCR implements MemoryCMR {
    private static final Log LOG = LogFactory.getLog(MemoryCMRImpl.class);
    protected int memoryTag = MemoryTag.MMAP_DEFAULT;
    private int madviseOpts = -1;

    public MemoryCMRImpl(FilesFacade ff, LPSZ name, long size, int memoryTag) {
        of(ff, name, 0, size, memoryTag, 0);
    }

    public MemoryCMRImpl() {
        // intentionally left empty
    }

    @Override
    public void close() {
        clear();
        if (pageAddress != 0) {
            ff.munmap(pageAddress, size, memoryTag);
            LOG.debug().$("unmapped [pageAddress=").$(pageAddress)
                    .$(", size=").$(size)
                    .$(", tag=").$(memoryTag)
                    .I$();
            size = 0;
            pageAddress = 0;
        }
        if (ff != null && ff.close(fd)) {
            LOG.debug().$("closed [fd=").$(fd).I$();
            fd = -1;
        }
    }

    @Override
    public void extend(long newSize) {
        if (newSize > size) {
            setSize0(newSize);
        }
    }

    @Override
    public boolean isMapped(long offset, long len) {
        return offset + len <= size();
    }

    @Override
    public void of(FilesFacade ff, LPSZ name, long extendSegmentSize, long size, int memoryTag, long opts, int madviseOpts) {
        this.memoryTag = memoryTag;
        this.madviseOpts = madviseOpts;
        openFile(ff, name);
        if (size < 0) {
            size = ff.length(fd);
            if (size < 0) {
                close();
                throw CairoException.critical(ff.errno()).put("could not get length: ").put(name);
            }
        }
        assert !PARANOIA_MODE || size <= ff.length(fd) || size <= ff.length(fd); // Some tests simulate ff.length() to be 0 once.
        map(ff, name, size);
    }

    @Override
    public void smallFile(FilesFacade ff, LPSZ name, int memoryTag) {
        // Override default implementation to defer ff.length() call to use fd instead of path
        of(ff, name, ff.getPageSize(), -1, memoryTag, CairoConfiguration.O_NONE, -1);
    }

    @Override
    public void wholeFile(FilesFacade ff, LPSZ name, int memoryTag) {
        // Override default implementation to defer ff.length() call to use fd instead of path
        of(ff, name, ff.getMapPageSize(), -1, memoryTag, CairoConfiguration.O_NONE, -1);
    }

    private void openFile(FilesFacade ff, LPSZ name) {
        close();
        this.ff = ff;
        fd = TableUtils.openRO(ff, name, LOG);
    }

    private void setSize0(long newSize) {
        try {
            if (size > 0) {
                pageAddress = TableUtils.mremap(ff, fd, pageAddress, size, newSize, Files.MAP_RO, memoryTag);
            } else {
                assert pageAddress == 0;
                pageAddress = TableUtils.mapRO(ff, fd, newSize, memoryTag);
            }
            ff.madvise(pageAddress, newSize, madviseOpts);
            size = newSize;
        } catch (Throwable e) {
            close();
            throw e;
        }
    }

    protected void map(FilesFacade ff, LPSZ name, final long size) {
        this.size = size;
        if (size > 0) {
            try {
                this.pageAddress = TableUtils.mapRO(ff, fd, size, memoryTag);
                ff.madvise(pageAddress, size, madviseOpts);
            } catch (Throwable e) {
                close();
                throw e;
            }
        } else {
            assert size > -1;
            this.pageAddress = 0;
        }

        // ---------------V leave a space here for alignment with open log message
        LOG.debug().$("map  [file=").$(name).$(", fd=").$(fd).$(", pageSize=").$(size).$(", size=").$(this.size).$(']').$();
    }
}