kv_catalog.h

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// kv_catalog.h

#pragma once

#include <map>
#include <memory>
#include <string>

#include "mongo/base/string_data.h"
#include "mongo/db/catalog/collection_options.h"
#include "mongo/db/record_id.h"
#include "mongo/db/storage/bson_collection_catalog_entry.h"
#include "mongo/db/storage/kv/kv_prefix.h"
#include "mongo/stdx/mutex.h"

namespace mongo {

class OperationContext;
class RecordStore;

class KVCatalog {
public:
    class FeatureTracker;

    KVCatalog(RecordStore* rs, bool directoryPerDb, bool directoryForIndexes);
    ~KVCatalog();

    void init(OperationContext* opCtx);

    void getAllCollections(std::vector<std::string>* out) const;

    Status newCollection(OperationContext* opCtx,
                         StringData ns,
                         const CollectionOptions& options,
                         KVPrefix prefix);

    std::string getCollectionIdent(StringData ns) const;

    std::string getIndexIdent(OperationContext* opCtx, StringData ns, StringData idName) const;

    BSONCollectionCatalogEntry::MetaData getMetaData(OperationContext* opCtx, StringData ns) const;
    void putMetaData(OperationContext* opCtx,
                     StringData ns,
                     BSONCollectionCatalogEntry::MetaData& md);

    Status renameCollection(OperationContext* opCtx,
                            StringData fromNS,
                            StringData toNS,
                            bool stayTemp);

    Status dropCollection(OperationContext* opCtx, StringData ns);

    std::vector<std::string> getAllIdentsForDB(StringData db) const;
    std::vector<std::string> getAllIdents(OperationContext* opCtx) const;

    bool isUserDataIdent(StringData ident) const;

    FeatureTracker* getFeatureTracker() const {
        invariant(_featureTracker);
        return _featureTracker.get();
    }

    RecordStore* getRecordStore() {
        return _rs;
    }

private:
    class AddIdentChange;
    class RemoveIdentChange;

    BSONObj _findEntry(OperationContext* opCtx, StringData ns, RecordId* out = NULL) const;

    std::string _newUniqueIdent(StringData ns, const char* kind);

    // Helpers only used by constructor and init(). Don't call from elsewhere.
    static std::string _newRand();
    bool _hasEntryCollidingWithRand() const;

    RecordStore* _rs;  // not owned
    const bool _directoryPerDb;
    const bool _directoryForIndexes;

    // These two are only used for ident generation inside _newUniqueIdent.
    std::string _rand;  // effectively const after init() returns
    AtomicUInt64 _next;

    struct Entry {
        Entry() {}
        Entry(std::string i, RecordId l) : ident(i), storedLoc(l) {}
        std::string ident;
        RecordId storedLoc;
    };
    typedef std::map<std::string, Entry> NSToIdentMap;
    NSToIdentMap _idents;
    mutable stdx::mutex _identsLock;

    // Manages the feature document that may be present in the KVCatalog. '_featureTracker' is
    // guaranteed to be non-null after KVCatalog::init() is called.
    std::unique_ptr<FeatureTracker> _featureTracker;
};
}