filemap.h

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/*-------------------------------------------------------------------------
 *
 * filemap.h
 *
 * Copyright (c) 2013-2025, PostgreSQL Global Development Group
 *-------------------------------------------------------------------------
 */
#ifndef FILEMAP_H
#define FILEMAP_H
 
#include "datapagemap.h"
#include "storage/block.h"
#include "storage/relfilelocator.h"
#include "access/xlogdefs.h"
 
/* these enum values are sorted in the order we want actions to be processed */
typedef enum
{
    FILE_ACTION_UNDECIDED = 0,  /* not decided yet */
 
    FILE_ACTION_CREATE,         /* create local directory or symbolic link */
    FILE_ACTION_COPY,           /* copy whole file, overwriting if exists */
    FILE_ACTION_COPY_TAIL,      /* copy tail from 'source_size' to
                                 * 'target_size' */
    FILE_ACTION_NONE,           /* no action (we might still copy modified
                                 * blocks based on the parsed WAL) */
    FILE_ACTION_TRUNCATE,       /* truncate local file to 'newsize' bytes */
    FILE_ACTION_REMOVE,         /* remove local file / directory / symlink */
} file_action_t;
 
typedef enum
{
    FILE_TYPE_UNDEFINED = 0,
 
    FILE_TYPE_REGULAR,
    FILE_TYPE_DIRECTORY,
    FILE_TYPE_SYMLINK,
} file_type_t;
 
typedef enum
{
    FILE_CONTENT_TYPE_OTHER = 0,
    FILE_CONTENT_TYPE_RELATION,
    FILE_CONTENT_TYPE_WAL
} file_content_type_t;
 
/*
 * For every file found in the local or remote system, we have a file entry
 * that contains information about the file on both systems.  For relation
 * files, there is also a page map that marks pages in the file that were
 * changed in the target after the last common checkpoint.
 *
 * When gathering information, these are kept in a hash table, private to
 * filemap.c.  decide_file_actions() fills in the 'action' field, sorts all
 * the entries, and returns them in an array, ready for executing the actions.
 */
typedef struct file_entry_t
{
    uint32      status;         /* hash status */
 
    const char *path;
    file_content_type_t content_type;
 
    /*
     * Status of the file in the target.
     */
    bool        target_exists;
    file_type_t target_type;
    size_t      target_size;    /* for a regular file */
    char       *target_link_target; /* for a symlink */
 
    /*
     * Pages that were modified in the target and need to be replaced from the
     * source.
     */
    datapagemap_t target_pages_to_overwrite;
 
    /*
     * Status of the file in the source.
     */
    bool        source_exists;
    file_type_t source_type;
    size_t      source_size;
    char       *source_link_target; /* for a symlink */
 
    /*
     * What will we do to the file?
     */
    file_action_t action;
} file_entry_t;
 
/*
 * This contains the final decisions on what to do with each file.
 * 'entries' array contains an entry for each file, sorted in the order
 * that their actions should executed.
 */
typedef struct filemap_t
{
    /* Summary information, filled by calculate_totals() */
    uint64      total_size;     /* total size of the source cluster */
    uint64      fetch_size;     /* number of bytes that needs to be copied */
 
    int         nentries;       /* size of 'entries' array */
    file_entry_t *entries[FLEXIBLE_ARRAY_MEMBER];
} filemap_t;
 
/* Functions for populating the filemap */
extern void filehash_init(void);
extern void process_source_file(const char *path, file_type_t type,
                                size_t size, const char *link_target);
extern void process_target_file(const char *path, file_type_t type,
                                size_t size, const char *link_target);
extern void process_target_wal_block_change(ForkNumber forknum,
                                            RelFileLocator rlocator,
                                            BlockNumber blkno);
 
extern filemap_t *decide_file_actions(XLogSegNo last_common_segno);
extern void calculate_totals(filemap_t *filemap);
extern void print_filemap(filemap_t *filemap);
 
extern void keepwal_init(void);
extern void keepwal_add_entry(const char *path);
 
#endif                          /* FILEMAP_H */