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132 lines
3.2 KiB
C
132 lines
3.2 KiB
C
/*-------------------------------------------------------------------------
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*
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* local_source.c
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* Functions for using a local data directory as the source.
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*
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* Portions Copyright (c) 2013-2021, PostgreSQL Global Development Group
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*
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*-------------------------------------------------------------------------
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*/
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#include "postgres_fe.h"
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#include <fcntl.h>
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#include <unistd.h>
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#include "datapagemap.h"
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#include "file_ops.h"
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#include "filemap.h"
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#include "pg_rewind.h"
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#include "rewind_source.h"
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typedef struct
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{
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rewind_source common; /* common interface functions */
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const char *datadir; /* path to the source data directory */
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} local_source;
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static void local_traverse_files(rewind_source *source,
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process_file_callback_t callback);
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static char *local_fetch_file(rewind_source *source, const char *path,
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size_t *filesize);
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static void local_fetch_file_range(rewind_source *source, const char *path,
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off_t off, size_t len);
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static void local_finish_fetch(rewind_source *source);
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static void local_destroy(rewind_source *source);
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rewind_source *
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init_local_source(const char *datadir)
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{
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local_source *src;
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src = pg_malloc0(sizeof(local_source));
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src->common.traverse_files = local_traverse_files;
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src->common.fetch_file = local_fetch_file;
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src->common.queue_fetch_range = local_fetch_file_range;
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src->common.finish_fetch = local_finish_fetch;
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src->common.get_current_wal_insert_lsn = NULL;
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src->common.destroy = local_destroy;
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src->datadir = datadir;
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return &src->common;
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}
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static void
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local_traverse_files(rewind_source *source, process_file_callback_t callback)
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{
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traverse_datadir(((local_source *) source)->datadir, &process_source_file);
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}
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static char *
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local_fetch_file(rewind_source *source, const char *path, size_t *filesize)
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{
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return slurpFile(((local_source *) source)->datadir, path, filesize);
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}
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/*
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* Copy a file from source to target, starting at 'off', for 'len' bytes.
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*/
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static void
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local_fetch_file_range(rewind_source *source, const char *path, off_t off,
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size_t len)
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{
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const char *datadir = ((local_source *) source)->datadir;
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PGAlignedBlock buf;
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char srcpath[MAXPGPATH];
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int srcfd;
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off_t begin = off;
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off_t end = off + len;
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snprintf(srcpath, sizeof(srcpath), "%s/%s", datadir, path);
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srcfd = open(srcpath, O_RDONLY | PG_BINARY, 0);
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if (srcfd < 0)
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pg_fatal("could not open source file \"%s\": %m",
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srcpath);
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if (lseek(srcfd, begin, SEEK_SET) == -1)
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pg_fatal("could not seek in source file: %m");
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open_target_file(path, false);
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while (end - begin > 0)
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{
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ssize_t readlen;
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size_t len;
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if (end - begin > sizeof(buf))
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len = sizeof(buf);
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else
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len = end - begin;
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readlen = read(srcfd, buf.data, len);
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if (readlen < 0)
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pg_fatal("could not read file \"%s\": %m", srcpath);
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else if (readlen == 0)
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pg_fatal("unexpected EOF while reading file \"%s\"", srcpath);
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write_target_range(buf.data, begin, readlen);
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begin += readlen;
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}
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if (close(srcfd) != 0)
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pg_fatal("could not close file \"%s\": %m", srcpath);
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}
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static void
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local_finish_fetch(rewind_source *source)
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{
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/*
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* Nothing to do, local_fetch_file_range() copies the ranges immediately.
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*/
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}
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static void
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local_destroy(rewind_source *source)
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{
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pfree(source);
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}
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