livestatus/src/Table.h

   1 // +------------------------------------------------------------------+
   2 // |             ____ _               _        __  __ _  __           |
   3 // |            / ___| |__   ___  ___| | __   |  \/  | |/ /           |
   4 // |           | |   | '_ \ / _ \/ __| |/ /   | |\/| | ' /            |
   5 // |           | |___| | | |  __/ (__|   <    | |  | | . \            |
   6 // |            \____|_| |_|\___|\___|_|\_\___|_|  |_|_|\_\           |
   7 // |                                                                  |
   8 // | Copyright Mathias Kettner 2014             mk@mathias-kettner.de |
   9 // +------------------------------------------------------------------+
  10 //
  11 // This file is part of Check_MK.
  12 // The official homepage is at http://mathias-kettner.de/check_mk.
  13 //
  14 // check_mk is free software;  you can redistribute it and/or modify it
  15 // under the  terms of the  GNU General Public License  as published by
  16 // the Free Software Foundation in version 2.  check_mk is  distributed
  17 // in the hope that it will be useful, but WITHOUT ANY WARRANTY;  with-
  18 // out even the implied warranty of  MERCHANTABILITY  or  FITNESS FOR A
  19 // PARTICULAR PURPOSE. See the  GNU General Public License for more de-
  20 // tails. You should have  received  a copy of the  GNU  General Public
  21 // License along with GNU Make; see the file  COPYING.  If  not,  write
  22 // to the Free Software Foundation, Inc., 51 Franklin St,  Fifth Floor,
  23 // Boston, MA 02110-1301 USA.
  24
  25 #ifndef Table_h
  26 #define Table_h
  27
  28 #include "config.h"  // IWYU pragma: keep
  29 #include <map>
  30 #include <memory>
  31 #include <string>
  32 #include <utility>
  33 #include "Row.h"
  34 #include "contact_fwd.h"
  35 class Column;
  36 class DynamicColumn;
  37 class Logger;
  38 class MonitoringCore;
  39 class Query;
  40
  41 // NOTE: This macro leads to undefined behaviour for non-POD/non-standard-layout
  42 // classes, e.g. Entity, Host, etc., nevertheless we have to use it below. :-/
  43 #define DANGEROUS_OFFSETOF(typename, member) \
  44     (reinterpret_cast<size_t>(&(reinterpret_cast<typename *>(32))->member) - 32)
  45
  46 /// A table-like view for some underlying data, exposed via LQL.
  47 class Table {
  48 public:
  49     explicit Table(MonitoringCore *mc);
  50     virtual ~Table();
  51
  52     void addColumn(std::unique_ptr<Column> col);
  53     void addDynamicColumn(std::unique_ptr<DynamicColumn> dyncol);
  54
  55     template <typename Predicate>
  56     bool any_column(Predicate pred) const {
  57         for (auto &c : _columns) {
  58             if (pred(c.second)) {
  59                 return true;
  60             }
  61         }
  62         return false;
  63     }
  64
  65     /// The name of the table, as used in the GET command.
  66     virtual std::string name() const = 0;
  67
  68     /// \brief An optional prefix for column names.
  69     ///
  70     /// \todo Due to the way multisite works, column names are sometimes
  71     /// prefixed by a variation of the table name (e.g. "hosts" => "host_"), but
  72     /// the logic for this really shouldn't live on the cmc side. Furthermore,
  73     /// multisite sometimes even seems to use a *sequence* of prefixes, which is
  74     /// yet another a bug. Instead of fixing it there, it is currently papered
  75     /// over on the cmc side. :-/
  76     virtual std::string namePrefix() const = 0;
  77
  78     /// \brief Retrieve a column with a give name.
  79     ///
  80     /// If the name contains a ':' then we have a dynamic column with column
  81     /// arguments: The part before the colon is the column name of the dynamic
  82     /// column and the part after it is the name of the fresh, dynamically
  83     /// created column (up to the 2nd ':') and further arguments. This whole
  84     /// mechanism is e.g. used to access RRD metrics data.
  85     ///
  86     /// \todo This member function is virtual just because TableStateHistory and
  87     /// TableLog override it for some dubious reason: They first try the normal
  88     /// lookup, and if that didn't find a column, the lookup is retried with a
  89     /// "current_" prefix. This logic should probably not live in cmc at all.
  90     virtual std::shared_ptr<Column> column(std::string colname) const;
  91
  92     // NOTE: We can't make the query argument 'const' right now, because we call
  93     // the non-const Query::processDataset() member function on it. This is a
  94     // bit ugly, but only a minor issue: Each Query instance is only accessed in
  95     // the thread which created it. Splitting up the Query class into a const
  96     // and a non-const part can probably fix that wart.
  97     //
  98     // A much bigger problem is that we can't make answerQuery() itself 'const',
  99     // because its impementations in TableStateHistory and TableCachedStatehist
 100     // are non-const. Tables are shared between threads and the locking in the
 101     // problematic answerQuery() implementations is a "bit" chaotic, so this can
 102     // be a real correctness problem! This has to be fixed...
 103     virtual void answerQuery(Query *query) = 0;
 104     virtual bool isAuthorized(Row row, const contact *ctc) const;
 105     virtual Row findObject(const std::string &objectspec) const;
 106
 107     template <typename T>
 108     const T *rowData(Row row) const {
 109         return row.rawData<T>();
 110     }
 111
 112     MonitoringCore *core() const { return _mc; }
 113     Logger *logger() const;
 114
 115 private:
 116     MonitoringCore *_mc;
 117
 118     std::unique_ptr<Column> dynamicColumn(const std::string &colname,
 119                                           const std::string &rest) const;
 120
 121     std::map<std::string, std::shared_ptr<Column>> _columns;
 122     std::map<std::string, std::unique_ptr<DynamicColumn>> _dynamic_columns;
 123 };
 124
 125 #endif  // Table_h