wiredtiger_size_storer.h

Go to the documentation of this file.

// wiredtiger_size_storer.h

#pragma once

#include <string>

#include <wiredtiger.h>

#include "mongo/base/string_data.h"
#include "mongo/db/storage/wiredtiger/wiredtiger_session_cache.h"
#include "mongo/platform/atomic_word.h"
#include "mongo/stdx/mutex.h"
#include "mongo/util/string_map.h"

namespace mongo {

class WiredTigerSizeStorer {
public:
    struct SizeInfo {
        ~SizeInfo() {
            invariant(!_dirty.load());
        }
        AtomicInt64 numRecords;
        AtomicInt64 dataSize;

    private:
        friend WiredTigerSizeStorer;
        AtomicBool _dirty;
    };

    WiredTigerSizeStorer(WT_CONNECTION* conn,
                         const std::string& storageUri,
                         const bool readOnly = false);
    ~WiredTigerSizeStorer();

    void store(StringData uri, std::shared_ptr<SizeInfo> sizeInfo);

    std::shared_ptr<SizeInfo> load(StringData uri) const;

    void flush(bool syncToDisk);

private:
    const WiredTigerSession _session;
    const bool _readOnly;
    // Guards _cursor. Acquire *before* _bufferMutex.
    mutable stdx::mutex _cursorMutex;
    WT_CURSOR* _cursor;  // pointer is const after constructor

    using Buffer = StringMap<std::shared_ptr<SizeInfo>>;

    mutable stdx::mutex _bufferMutex;  // Guards _buffer
    Buffer _buffer;
};
}