remote-database.h

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/* Copyright (C) 2006,2007,2009,2010,2011,2014,2015,2019,2020 Olly Betts
 * Copyright (C) 2007,2009,2010 Lemur Consulting Ltd
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; either version 2 of the
 * License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
 */

#ifndef XAPIAN_INCLUDED_REMOTE_DATABASE_H
#define XAPIAN_INCLUDED_REMOTE_DATABASE_H

#include "backends/backends.h"
#include "backends/database.h"
#include "api/omenquireinternal.h"
#include "api/queryinternal.h"
#include "net/remoteconnection.h"
#include "backends/valuestats.h"
#include "xapian/weight.h"

namespace Xapian {
    class RSet;
}

class NetworkPostList;

class RemoteDatabase : public Xapian::Database::Internal {
    void operator=(const RemoteDatabase &);

    RemoteDatabase(const RemoteDatabase &);

    mutable OwnedRemoteConnection link;

    mutable Xapian::doccount doccount;

    mutable Xapian::docid lastdocid;

    mutable Xapian::termcount doclen_lbound;

    mutable Xapian::termcount doclen_ubound;

    mutable Xapian::totallength total_length;

    mutable bool has_positional_info;

    mutable int pending_reply = -1;

    mutable string uuid;

    string context;

    mutable bool cached_stats_valid;

    mutable ValueStats mru_valstats;

    mutable Xapian::valueno mru_slot;

    mutable bool uncommitted_changes = false;

    bool update_stats(message_type msg_code = MSG_UPDATE,
                      const std::string & body = std::string()) const;

  protected:
    RemoteDatabase(int fd, double timeout_, const string & context_,
                   bool writable, int flags);

    reply_type get_message(std::string& message,
                           reply_type required_type,
                           reply_type required_type2) const;

    void get_message(std::string& message,
                     reply_type required_type) const {
        (void)get_message(message, required_type, required_type);
    }

    bool get_message_or_done(std::string& message,
                             reply_type required_type) const {
        return get_message(message, required_type, REPLY_DONE) != REPLY_DONE;
    }

    void send_message(message_type type, const string & data) const;

    void do_close();

    bool get_posting(Xapian::docid &did, double &w, string &value);

    double timeout;

  public:
    void keep_alive();

    void set_query(const Xapian::Query& query,
                   Xapian::termcount qlen,
                   Xapian::doccount collapse_max,
                   Xapian::valueno collapse_key,
                   Xapian::Enquire::docid_order order,
                   Xapian::valueno sort_key,
                   Xapian::Enquire::Internal::sort_setting sort_by,
                   bool sort_value_forward,
                   double time_limit,
                   int percent_cutoff, double weight_cutoff,
                   const Xapian::Weight *wtscheme,
                   const Xapian::RSet &omrset,
                   const vector<Xapian::Internal::opt_intrusive_ptr<Xapian::MatchSpy>> & matchspies);

    bool get_remote_stats(bool nowait, Xapian::Weight::Internal &out);

    void send_global_stats(Xapian::doccount first,
                           Xapian::doccount maxitems,
                           Xapian::doccount check_at_least,
                           const Xapian::Weight::Internal &stats);

    void get_mset(Xapian::MSet &mset,
                  const vector<Xapian::Internal::opt_intrusive_ptr<Xapian::MatchSpy>> & matchspies);

    TermList * open_metadata_keylist(const std::string & prefix) const;

    TermList * open_term_list(Xapian::docid did) const;

    TermList * open_allterms(const string & prefix) const;

    bool has_positions() const;

    bool reopen();

    void close();

    LeafPostList * open_post_list(const string & tname) const;

    Xapian::doccount read_post_list(const string &term, NetworkPostList & pl) const;

    PositionList * open_position_list(Xapian::docid did,
                                      const string & tname) const;

    Xapian::Document::Internal * open_document(Xapian::docid did, bool lazy) const;

    Xapian::doccount get_doccount() const;

    Xapian::docid get_lastdocid() const;

    Xapian::totallength get_total_length() const;

    Xapian::termcount get_doclength(Xapian::docid did) const;
    Xapian::termcount get_unique_terms(Xapian::docid did) const;

    bool term_exists(const string & tname) const;

    void get_freqs(const string & term,
                   Xapian::doccount * termfreq_ptr,
                   Xapian::termcount * collfreq_ptr) const;

    void read_value_stats(Xapian::valueno slot) const;
    Xapian::doccount get_value_freq(Xapian::valueno slot) const;
    std::string get_value_lower_bound(Xapian::valueno slot) const;
    std::string get_value_upper_bound(Xapian::valueno slot) const;

    Xapian::termcount get_doclength_lower_bound() const;
    Xapian::termcount get_doclength_upper_bound() const;
    Xapian::termcount get_wdf_upper_bound(const string & term) const;

    void commit();

    void cancel();

    Xapian::docid add_document(const Xapian::Document & doc);

    void delete_document(Xapian::docid did);
    void delete_document(const std::string & unique_term);

    void replace_document(Xapian::docid did, const Xapian::Document & doc);
    Xapian::docid replace_document(const std::string & unique_term,
                                   const Xapian::Document & document);

    std::string get_uuid() const;

    string get_metadata(const string & key) const;

    void set_metadata(const string & key, const string & value);

    void add_spelling(const std::string&, Xapian::termcount) const;

    void remove_spelling(const std::string&, Xapian::termcount freqdec) const;

    int get_backend_info(string * path) const {
        if (path) *path = context;
        return BACKEND_REMOTE;
    }

    bool locked() const;
};

#endif // XAPIAN_INCLUDED_REMOTE_DATABASE_H