extent_manager.h

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// extent_manager.h

#pragma once

#include <memory>
#include <string>
#include <vector>

#include "mongo/base/status.h"
#include "mongo/base/string_data.h"
#include "mongo/db/storage/mmap_v1/diskloc.h"

namespace mongo {

class DataFile;
class DataFileVersion;
class MmapV1RecordHeader;
class RecordFetcher;
class OperationContext;

struct Extent;

class ExtentManager {
    MONGO_DISALLOW_COPYING(ExtentManager);

public:
    ExtentManager() {}

    class Factory {
    public:
        virtual ~Factory() = default;
        virtual std::unique_ptr<ExtentManager> create(StringData dbname,
                                                      StringData path,
                                                      bool directoryPerDB) = 0;
    };

    virtual ~ExtentManager() {}

    virtual void close(OperationContext* opCtx) = 0;

    virtual Status init(OperationContext* opCtx) = 0;

    virtual int numFiles() const = 0;
    virtual long long fileSize() const = 0;

    // must call Extent::reuse on the returned extent
    virtual DiskLoc allocateExtent(OperationContext* opCtx,
                                   bool capped,
                                   int size,
                                   bool enforceQuota) = 0;

    virtual void freeExtents(OperationContext* opCtx, DiskLoc firstExt, DiskLoc lastExt) = 0;

    virtual void freeExtent(OperationContext* opCtx, DiskLoc extent) = 0;

    virtual void freeListStats(OperationContext* opCtx,
                               int* numExtents,
                               int64_t* totalFreeSizeBytes) const = 0;

    virtual MmapV1RecordHeader* recordForV1(const DiskLoc& loc) const = 0;

    virtual std::unique_ptr<RecordFetcher> recordNeedsFetch(const DiskLoc& loc) const = 0;

    virtual Extent* extentForV1(const DiskLoc& loc) const = 0;

    virtual DiskLoc extentLocForV1(const DiskLoc& loc) const = 0;

    virtual Extent* getExtent(const DiskLoc& loc, bool doSanityCheck = true) const = 0;

    virtual int maxSize() const = 0;

    virtual int minSize() const {
        return 0x1000;
    }

    virtual int followupSize(int recordLen, int lastExtentLen) const;

    virtual int initialSize(int recordLen) const;

    virtual int quantizeExtentSize(int size) const;

    // see cacheHint methods
    enum HintType { Sequential, Random };
    class CacheHint {
    public:
        virtual ~CacheHint() {}
    };
    virtual CacheHint* cacheHint(const DiskLoc& extentLoc, const HintType& hint) = 0;

    virtual DataFileVersion getFileFormat(OperationContext* opCtx) const = 0;
    virtual void setFileFormat(OperationContext* opCtx, DataFileVersion newVersion) = 0;

    virtual const DataFile* getOpenFile(int n) const = 0;
};

}  // namespace mongo