log0files_dict.h

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/**************************************************/ /**
 @file include/log0files_dict.h
 
 In-memory dictionary of log files (keeps their meta data).
 
 The dictionary is built by the @see log_files_find_and_analyze().
 
 *******************************************************/
 
#ifndef log0files_dict_h
#define log0files_dict_h
 
/* std::for_each */
#include <algorithm>
 
/* std::iterator */
#include <iterator>
 
/* Log_file, Log_file_id, LOG_START_LSN */
#include "log0types.h"
 
/* os_offset_t */
#include "os0file.h"
 
/* ut::map */
#include "ut0ut.h"
 
/** In-memory dictionary of meta data of existing log files.
This is a plain data structure only. It has no dependency. */
class Log_files_dict {
 private:
  using Log_files_map = ut::map<Log_file_id, Log_file>;
  using Log_files_map_iterator = typename Log_files_map::const_iterator;
 
 public:
  class Const_iterator {
   public:
    using iterator_category = std::bidirectional_iterator_tag;
    using value_type = Log_file;
    using difference_type = std::ptrdiff_t;
    using pointer = const Log_file *;
    using reference = const Log_file &;
 
    explicit Const_iterator(Log_files_dict::Log_files_map_iterator it);
    const Log_file &operator*() const;
    const Log_file *operator->() const;
    Const_iterator &operator++();
    Const_iterator operator++(int);
    Const_iterator &operator--();
    Const_iterator operator--(int);
    bool operator==(const Const_iterator &rhs) const;
    bool operator!=(const Const_iterator &rhs) const;
 
   private:
    Log_files_dict::Log_files_map_iterator m_it;
  };
 
  /** Constructs an empty dictionary. */
  explicit Log_files_dict(Log_files_context &files_ctx);
 
  Log_files_dict(Log_files_dict &&other);
  Log_files_dict &operator=(Log_files_dict &&other);
 
  /** @return context within which files exist */
  const Log_files_context &ctx() const;
 
  /** Searches for an existing log file, that contains the provided lsn.
  @param[in]  lsn       lsn to search for
  @retval iterator pointing to the log file if file has been found
  @retval end() if there was no file containing the provided lsn */
  Const_iterator find(lsn_t lsn) const;
 
  /** Provides log file for the given file id.
  @param[in]  file_id   id of the log file
  @return pointer to the log file */
  Const_iterator file(Log_file_id file_id) const;
 
  /** Clears the whole dictionary. */
  void clear();
 
  /** Removes the meta data about the given log file (which denotes
  the file does not exist anymore) from this data structure.
  @param[in]  file_id   id of the log file */
  void erase(Log_file_id file_id);
 
  /** Add meta data for the existing log file. It asserts that the meta data
  for that file has not been added yet to this data structure.
  @see Log_file_handle::m_encryption_metadata
  @param[in]  file_id              id of the log file
  @param[in]  size_in_bytes        size of the log file (in bytes)
  @param[in]  start_lsn            lsn of the first data byte in file
  @param[in]  full                 true iff file is marked as full
  @param[in]  consumed             true iff file is marked as consumed
  @param[in]  encryption_metadata  encryption metadata */
  void add(Log_file_id file_id, os_offset_t size_in_bytes, lsn_t start_lsn,
           bool full, bool consumed, Encryption_metadata &encryption_metadata);
 
  /** Add meta data for the existing log file. It asserts that the meta data
  for that file has not been added yet to this data structure.
  @see Log_file_handle::m_encryption_metadata
  @param[in]  file_id              id of the log file
  @param[in]  size_in_bytes        size of the log file (in bytes)
  @param[in]  start_lsn            lsn of the first data byte in file
  @param[in]  full                 true iff file is marked as full
  @param[in]  encryption_metadata  encryption metadata */
  void add(Log_file_id file_id, os_offset_t size_in_bytes, lsn_t start_lsn,
           bool full, Encryption_metadata &encryption_metadata);
 
  /** Marks a given log file as consumed.
  @param[in]  file_id         id of the log file */
  void set_consumed(Log_file_id file_id);
 
  /** Marks a given log file as full.
  @param[in]  file_id         id of the log file */
  void set_full(Log_file_id file_id);
 
  /** Marks a given log file as incomplete (undo marking as full).
  @param[in]  file_id         id of the log file */
  void set_incomplete(Log_file_id file_id);
 
  /** Changes size of the file. Updates m_end_lsn accordingly.
  @param[in]  file_id         id of the log file
  @param[in]  new_size        new size (expressed in bytes) */
  void set_size(Log_file_id file_id, os_offset_t new_size);
 
  /** @return iterator to the first log file (with the smallest id) */
  Const_iterator begin() const;
 
  /** @return iterator after the last log file */
  Const_iterator end() const;
 
  /** @return true iff structure is empty */
  bool empty() const;
 
  /** @return the oldest redo log file */
  const Log_file &front() const;
 
  /** @return the newest redo log file */
  const Log_file &back() const;
 
 private:
  /** Context within which log files exist. */
  const Log_files_context &m_files_ctx;
 
  /** Meta information about each existing redo log file. */
  Log_files_map m_files_by_id;
};
 
template <typename F>
void log_files_for_each(const Log_files_dict &files, F functor) {
  std::for_each(files.begin(), files.end(), functor);
}
 
/** Calls the given functor for each of existing log files on path
from a file containing start_lsn to a file containing end_lsn - 1.
Asserts that such a path exists (going through existing log files).
When the range is empty (start_lsn >= end_lsn), no file is visited.
@param[in]  files       in-memory dictionary of log files
@param[in]  start_lsn   path starts at file reported by find(start_lsn)
@param[in]  end_lsn     path ends in file with m_end_lsn >= end_lsn
@param[in]  functor     functor receiving a reference to Log_file */
template <typename F>
void log_files_for_each(const Log_files_dict &files, lsn_t start_lsn,
                        lsn_t end_lsn, F functor) {
  ut_a(start_lsn >= LOG_START_LSN);
  ut_a(start_lsn <= end_lsn);
  if (start_lsn == end_lsn) {
    return;
  }
 
  auto begin = files.find(start_lsn);
  ut_a(begin != files.end());
  ut_a(begin->m_start_lsn <= start_lsn);
 
  auto end = files.find(end_lsn - 1);
  ut_a(end != files.end());
  ut_a(end_lsn <= end->m_end_lsn);
  end++;
 
  ut_a(end == files.end() || end_lsn <= end->m_start_lsn);
 
  std::for_each(begin, end, functor);
}
 
/** Computes logical capacity for the given physical size of the redo log file.
@param[in]  file_size_in_bytes    total size of file, expressed in bytes
@param[out] lsn_capacity          logical capacity of the file
@retval true    succeeded to compute the logical capacity
@retval false   params were invalid (file size was too small or too big) */
bool log_file_compute_logical_capacity(os_offset_t file_size_in_bytes,
                                       lsn_t &lsn_capacity);
 
/** Computes end_lsn for the given: start_lsn and size of the redo log file.
@param[in]  start_lsn             LSN of the first data byte within the file
@param[in]  file_size_in_bytes    total size of file, expressed in bytes
@param[out] end_lsn               LSN after the last data byte within the file
@retval true    succeeded to compute end_lsn
@retval false   params were invalid */
bool log_file_compute_end_lsn(lsn_t start_lsn, os_offset_t file_size_in_bytes,
                              lsn_t &end_lsn);
 
/** Counts the total number of existing log files.
@param[in]  files   in-memory dictionary of log files
@return number of existing log files. */
size_t log_files_number_of_existing_files(const Log_files_dict &files);
 
/** Counts the total number of existing and marked as consumed log files.
@param[in]  files   in-memory dictionary of log files
@return number of existing and marked as consumed log files. */
size_t log_files_number_of_consumed_files(const Log_files_dict &files);
 
/** Computes the total size of the existing log files (sum of sizes).
@note Each file starts with LOG_FILE_HDR_SIZE bytes of headers.
@param[in]  files   in-memory dictionary of log files
@return computed total size of existing log files */
os_offset_t log_files_size_of_existing_files(const Log_files_dict &files);
 
/** Computes the total capacity of the existing log files (sum of capacities).
@note Capacity of a file is smaller than size of the file by LOG_FILE_HDR_SIZE.
@param[in]  files   in-memory dictionary of log files
@return computed total capacity of existing log files */
lsn_t log_files_capacity_of_existing_files(const Log_files_dict &files);
 
/** Finds the largest existing log file (with the largest m_size_in_bytes).
@param[in]  files   in-memory dictionary of log files
@return the largest file or files.end() if there is no file at all */
Log_files_dict::Const_iterator log_files_find_largest(
    const Log_files_dict &files);
 
#endif /* !log0files_dict_h */