archive_waldump.c File Reference

#include "postgres_fe.h"
#include <unistd.h>
#include "access/xlog_internal.h"
#include "common/file_perm.h"
#include "common/hashfn.h"
#include "common/logging.h"
#include "fe_utils/simple_list.h"
#include "pg_waldump.h"
#include "lib/simplehash.h"

Include dependency graph for archive_waldump.c:

Go to the source code of this file.

Data Structures
struct	ArchivedWALFile
struct	astreamer_waldump

Macros
#define	READ_CHUNK_SIZE   (128 * 1024)
#define	READ_ANY_WAL(privateInfo)   ((privateInfo)->start_segno == 0)
#define	SH_PREFIX   ArchivedWAL
#define	SH_ELEMENT_TYPE   ArchivedWALFile
#define	SH_KEY_TYPE   const char *
#define	SH_KEY   fname
#define	SH_HASH_KEY(tb, key)   hash_string_pointer(key)
#define	SH_EQUAL(tb, a, b)   (strcmp(a, b) == 0)
#define	SH_SCOPE   static inline
#define	SH_RAW_ALLOCATOR   pg_malloc0
#define	SH_DECLARE
#define	SH_DEFINE

Typedefs
typedef struct ArchivedWALFile	ArchivedWALFile
typedef struct astreamer_waldump	astreamer_waldump

Functions
static uint32	hash_string_pointer (const char *s)
static ArchivedWALFile *	get_archive_wal_entry (const char *fname, XLogDumpPrivate *privateInfo)
static int	read_archive_file (XLogDumpPrivate *privateInfo, Size count)
static void	setup_tmpwal_dir (const char *waldir)
static void	cleanup_tmpwal_dir_atexit (void)
static FILE *	prepare_tmp_write (const char *fname, XLogDumpPrivate *privateInfo)
static void	perform_tmp_write (const char *fname, StringInfo buf, FILE *file)
static astreamer *	astreamer_waldump_new (XLogDumpPrivate *privateInfo)
static void	astreamer_waldump_content (astreamer *streamer, astreamer_member *member, const char *data, int len, astreamer_archive_context context)
static void	astreamer_waldump_finalize (astreamer *streamer)
static void	astreamer_waldump_free (astreamer *streamer)
static bool	member_is_wal_file (astreamer_waldump *mystreamer, astreamer_member *member, char **fname)
void	init_archive_reader (XLogDumpPrivate *privateInfo, pg_compress_algorithm compression)
void	free_archive_reader (XLogDumpPrivate *privateInfo)
int	read_archive_wal_page (XLogDumpPrivate *privateInfo, XLogRecPtr targetPagePtr, Size count, char *readBuff)
void	free_archive_wal_entry (const char *fname, XLogDumpPrivate *privateInfo)

Variables
char *	TmpWalSegDir = NULL
static const astreamer_ops	astreamer_waldump_ops

Macro Definition Documentation

READ_ANY_WAL

#define READ_ANY_WAL

(

privateInfo

)

((privateInfo)->start_segno == 0)

Definition at line 38 of file archive_waldump.c.

READ_CHUNK_SIZE

#define READ_CHUNK_SIZE   (128 * 1024)

Definition at line 29 of file archive_waldump.c.

SH_DECLARE

#define SH_DECLARE

Definition at line 80 of file archive_waldump.c.

SH_DEFINE

#define SH_DEFINE

Definition at line 81 of file archive_waldump.c.

SH_ELEMENT_TYPE

#define SH_ELEMENT_TYPE   ArchivedWALFile

Definition at line 73 of file archive_waldump.c.

SH_EQUAL

#define SH_EQUAL	(		tb,
			a,
			b
	)		(strcmp(a, b) == 0)

Definition at line 77 of file archive_waldump.c.

SH_HASH_KEY

#define SH_HASH_KEY	(		tb,
			key
	)		hash_string_pointer(key)

Definition at line 76 of file archive_waldump.c.

SH_KEY

#define SH_KEY   fname

Definition at line 75 of file archive_waldump.c.

SH_KEY_TYPE

#define SH_KEY_TYPE   const char *

Definition at line 74 of file archive_waldump.c.

SH_PREFIX

#define SH_PREFIX   ArchivedWAL

Definition at line 72 of file archive_waldump.c.

SH_RAW_ALLOCATOR

#define SH_RAW_ALLOCATOR   pg_malloc0

Definition at line 79 of file archive_waldump.c.

SH_SCOPE

#define SH_SCOPE   static inline

Definition at line 78 of file archive_waldump.c.

Typedef Documentation

ArchivedWALFile

typedef struct ArchivedWALFile ArchivedWALFile

astreamer_waldump

typedef struct astreamer_waldump astreamer_waldump

Function Documentation

astreamer_waldump_content()

static void astreamer_waldump_content ( astreamer *  streamer, astreamer_member *  member, const char *  data, int  len, astreamer_archive_context  context  )

static

Definition at line 693 of file archive_waldump.c.

{
    astreamer_waldump *mystreamer = (astreamer_waldump *) streamer;
    XLogDumpPrivate *privateInfo = mystreamer->privateInfo;
 
    Assert(context != ASTREAMER_UNKNOWN);
 
    switch (context)
    {
        case ASTREAMER_MEMBER_HEADER:
            {
                char       *fname = NULL;
                ArchivedWALFile *entry;
                bool        found;
 
                pg_log_debug("reading \"%s\"", member->pathname);
 
                if (!member_is_wal_file(mystreamer, member, &fname))
                    break;
 
                /*
                 * Skip range filtering during initial startup, before the WAL
                 * segment size and segment number bounds are known.
                 */
                if (!READ_ANY_WAL(privateInfo))
                {
                    XLogSegNo   segno;
                    TimeLineID  timeline;
 
                    /*
                     * Skip the segment if the timeline does not match, if it
                     * falls outside the caller-specified range.
                     */
                    XLogFromFileName(fname, &timeline, &segno, privateInfo->segsize);
                    if (privateInfo->timeline != timeline ||
                        privateInfo->start_segno > segno ||
                        privateInfo->end_segno < segno)
                    {
                        pfree(fname);
                        break;
                    }
                }
 
                entry = ArchivedWAL_insert(privateInfo->archive_wal_htab,
                                           fname, &found);
 
                /*
                 * Shouldn't happen, but if it does, simply ignore the
                 * duplicate WAL file.
                 */
                if (found)
                {
                    pg_log_warning("ignoring duplicate WAL \"%s\" found in archive \"%s\"",
                                   member->pathname, privateInfo->archive_name);
                    pfree(fname);
                    break;
                }
 
                entry->buf = makeStringInfo();
                entry->spilled = false;
                entry->read_len = 0;
                privateInfo->cur_file = entry;
            }
            break;
 
        case ASTREAMER_MEMBER_CONTENTS:
            if (privateInfo->cur_file)
            {
                appendBinaryStringInfo(privateInfo->cur_file->buf, data, len);
                privateInfo->cur_file->read_len += len;
            }
            break;
 
        case ASTREAMER_MEMBER_TRAILER:
 
            /*
             * End of this tar member; mark cur_file NULL so subsequent
             * content callbacks (if any) know no WAL file is currently
             * active.
             */
            privateInfo->cur_file = NULL;
            break;
 
        case ASTREAMER_ARCHIVE_TRAILER:
            break;
 
        default:
            /* Shouldn't happen. */
            pg_fatal("unexpected state while parsing tar file");
    }
}

References appendBinaryStringInfo(), XLogDumpPrivate::archive_name, XLogDumpPrivate::archive_wal_htab, Assert, ASTREAMER_ARCHIVE_TRAILER, ASTREAMER_MEMBER_CONTENTS, ASTREAMER_MEMBER_HEADER, ASTREAMER_MEMBER_TRAILER, ASTREAMER_UNKNOWN, ArchivedWALFile::buf, XLogDumpPrivate::cur_file, data, XLogDumpPrivate::end_segno, fb(), len, makeStringInfo(), member_is_wal_file(), astreamer_member::pathname, pfree(), pg_fatal, pg_log_debug, pg_log_warning, READ_ANY_WAL, ArchivedWALFile::read_len, XLogDumpPrivate::segsize, ArchivedWALFile::spilled, XLogDumpPrivate::start_segno, XLogDumpPrivate::timeline, and XLogFromFileName().

astreamer_waldump_finalize()

static void astreamer_waldump_finalize ( astreamer *  streamer )

static

Definition at line 792 of file archive_waldump.c.

{
    Assert(streamer->bbs_next == NULL);
}

References Assert, astreamer::bbs_next, and fb().

astreamer_waldump_free()

static void astreamer_waldump_free ( astreamer *  streamer )

static

Definition at line 801 of file archive_waldump.c.

{
    Assert(streamer->bbs_next == NULL);
    pfree(streamer);
}

References Assert, astreamer::bbs_next, fb(), and pfree().

astreamer_waldump_new()

static astreamer * astreamer_waldump_new ( XLogDumpPrivate *  privateInfo )

static

Definition at line 673 of file archive_waldump.c.

{
    astreamer_waldump *streamer;
 
    streamer = palloc0_object(astreamer_waldump);
    *((const astreamer_ops **) &streamer->base.bbs_ops) =
        &astreamer_waldump_ops;
 
    streamer->privateInfo = privateInfo;
 
    return &streamer->base;
}

References astreamer_waldump_ops, astreamer_waldump::base, astreamer::bbs_ops, palloc0_object, and astreamer_waldump::privateInfo.

Referenced by init_archive_reader().

cleanup_tmpwal_dir_atexit()

static void cleanup_tmpwal_dir_atexit ( void  )

static

Definition at line 601 of file archive_waldump.c.

{
    Assert(TmpWalSegDir != NULL);
 
    rmtree(TmpWalSegDir, true);
 
    TmpWalSegDir = NULL;
}

References Assert, fb(), rmtree(), and TmpWalSegDir.

Referenced by prepare_tmp_write().

free_archive_reader()

void free_archive_reader

(

XLogDumpPrivate *

privateInfo

)

Definition at line 234 of file archive_waldump.c.

{
    /*
     * NB: Normally, astreamer_finalize() is called before astreamer_free() to
     * flush any remaining buffered data or to ensure the end of the tar
     * archive is reached.  However, when decoding WAL, once we hit the end
     * LSN, any remaining buffered data or unread portion of the archive can
     * be safely ignored.
     */
    astreamer_free(privateInfo->archive_streamer);
 
    /* Free any remaining hash table entries and their buffers. */
    if (privateInfo->archive_wal_htab != NULL)
    {
        ArchivedWAL_iterator iter;
        ArchivedWALFile *entry;
 
        ArchivedWAL_start_iterate(privateInfo->archive_wal_htab, &iter);
        while ((entry = ArchivedWAL_iterate(privateInfo->archive_wal_htab,
                                            &iter)) != NULL)
        {
            if (entry->buf != NULL)
                destroyStringInfo(entry->buf);
        }
        ArchivedWAL_destroy(privateInfo->archive_wal_htab);
        privateInfo->archive_wal_htab = NULL;
    }
 
    /* Free the reusable read buffer. */
    if (privateInfo->archive_read_buf != NULL)
    {
        pg_free(privateInfo->archive_read_buf);
        privateInfo->archive_read_buf = NULL;
    }
 
    /* Close the file. */
    if (close(privateInfo->archive_fd) != 0)
        pg_log_error("could not close file \"%s\": %m",
                     privateInfo->archive_name);
}

References XLogDumpPrivate::archive_fd, XLogDumpPrivate::archive_name, XLogDumpPrivate::archive_read_buf, XLogDumpPrivate::archive_streamer, XLogDumpPrivate::archive_wal_htab, astreamer_free(), ArchivedWALFile::buf, close, destroyStringInfo(), fb(), pg_free(), and pg_log_error.

Referenced by main().

free_archive_wal_entry()

void free_archive_wal_entry	(	const char *	fname,
		XLogDumpPrivate *	privateInfo
	)

Definition at line 415 of file archive_waldump.c.

{
    ArchivedWALFile *entry;
 
    entry = ArchivedWAL_lookup(privateInfo->archive_wal_htab, fname);
 
    if (entry == NULL)
        return;
 
    /* Destroy the buffer */
    destroyStringInfo(entry->buf);
    entry->buf = NULL;
 
    /* Remove temporary file if any */
    if (entry->spilled)
    {
        char        fpath[MAXPGPATH];
 
        snprintf(fpath, MAXPGPATH, "%s/%s", TmpWalSegDir, fname);
 
        if (unlink(fpath) == 0)
            pg_log_debug("removed file \"%s\"", fpath);
    }
 
    /* Clear cur_file if it points to the entry being freed */
    if (privateInfo->cur_file == entry)
        privateInfo->cur_file = NULL;
 
    ArchivedWAL_delete_item(privateInfo->archive_wal_htab, entry);
}

References XLogDumpPrivate::archive_wal_htab, ArchivedWALFile::buf, XLogDumpPrivate::cur_file, destroyStringInfo(), fb(), MAXPGPATH, pg_log_debug, snprintf, ArchivedWALFile::spilled, and TmpWalSegDir.

Referenced by init_archive_reader(), and TarWALDumpReadPage().

get_archive_wal_entry()

static ArchivedWALFile * get_archive_wal_entry ( const char *  fname, XLogDumpPrivate *  privateInfo  )

static

Definition at line 454 of file archive_waldump.c.

{
    ArchivedWALFile *entry = NULL;
    FILE       *write_fp = NULL;
 
    /*
     * Search the hash table first. If the entry is found, return it.
     * Otherwise, the requested WAL entry hasn't been read from the archive
     * yet; invoke the archive streamer to fetch it.
     */
    while (1)
    {
        /*
         * Search hash table.
         *
         * We perform the search inside the loop because a single iteration of
         * the archive reader may decompress and extract multiple files into
         * the hash table. One of these newly added files could be the one we
         * are seeking.
         */
        entry = ArchivedWAL_lookup(privateInfo->archive_wal_htab, fname);
 
        if (entry != NULL)
            return entry;
 
        /*
         * Capture the current entry before calling read_archive_file(),
         * because cur_file may advance to a new segment during streaming. We
         * hold this reference so we can flush any remaining buffer data and
         * close the write handle once we detect that cur_file has moved on.
         */
        entry = privateInfo->cur_file;
 
        /*
         * Fetch more data either when no current file is being tracked or
         * when its buffer has been fully flushed to the temporary file.
         */
        if (entry == NULL || entry->buf->len == 0)
        {
            if (read_archive_file(privateInfo, READ_CHUNK_SIZE) == 0)
                break;          /* archive file ended */
        }
 
        /*
         * Archive streamer is reading a non-WAL file or an irrelevant WAL
         * file.
         */
        if (entry == NULL)
            continue;
 
        /*
         * The streamer is producing a WAL segment that isn't the one asked
         * for; it must be arriving out of order.  Spill its data to disk so
         * it can be read back when needed.
         */
        Assert(strcmp(fname, entry->fname) != 0);
 
        /* Create a temporary file if one does not already exist */
        if (!entry->spilled)
        {
            write_fp = prepare_tmp_write(entry->fname, privateInfo);
            entry->spilled = true;
        }
 
        /* Flush data from the buffer to the file */
        perform_tmp_write(entry->fname, entry->buf, write_fp);
        resetStringInfo(entry->buf);
 
        /*
         * If cur_file changed since we captured entry above, the archive
         * streamer has finished this segment and moved on.  Close its spill
         * file handle so data is flushed to disk before the next segment
         * starts writing to a different handle.
         */
        if (entry != privateInfo->cur_file && write_fp != NULL)
        {
            fclose(write_fp);
            write_fp = NULL;
        }
    }
 
    /* Requested WAL segment not found */
    pg_fatal("could not find WAL \"%s\" in archive \"%s\"",
             fname, privateInfo->archive_name);
}

References XLogDumpPrivate::archive_name, XLogDumpPrivate::archive_wal_htab, Assert, ArchivedWALFile::buf, XLogDumpPrivate::cur_file, fb(), ArchivedWALFile::fname, StringInfoData::len, perform_tmp_write(), pg_fatal, prepare_tmp_write(), read_archive_file(), READ_CHUNK_SIZE, resetStringInfo(), and ArchivedWALFile::spilled.

Referenced by read_archive_wal_page().

hash_string_pointer()

static uint32 hash_string_pointer ( const char *  s )

static

Definition at line 855 of file archive_waldump.c.

{
    unsigned char *ss = (unsigned char *) s;
 
    return hash_bytes(ss, strlen(s));
}

References fb(), and hash_bytes().

init_archive_reader()

void init_archive_reader	(	XLogDumpPrivate *	privateInfo,
		pg_compress_algorithm	compression
	)

Definition at line 124 of file archive_waldump.c.

{
    int         fd;
    astreamer  *streamer;
    ArchivedWALFile *entry = NULL;
    XLogLongPageHeader longhdr;
    XLogSegNo   segno;
    TimeLineID  timeline;
 
    /* Open tar archive and store its file descriptor */
    fd = open_file_in_directory(privateInfo->archive_dir,
                                privateInfo->archive_name);
 
    if (fd < 0)
        pg_fatal("could not open file \"%s\"", privateInfo->archive_name);
 
    privateInfo->archive_fd = fd;
 
    streamer = astreamer_waldump_new(privateInfo);
 
    /* We must first parse the tar archive. */
    streamer = astreamer_tar_parser_new(streamer);
 
    /* If the archive is compressed, decompress before parsing. */
    if (compression == PG_COMPRESSION_GZIP)
        streamer = astreamer_gzip_decompressor_new(streamer);
    else if (compression == PG_COMPRESSION_LZ4)
        streamer = astreamer_lz4_decompressor_new(streamer);
    else if (compression == PG_COMPRESSION_ZSTD)
        streamer = astreamer_zstd_decompressor_new(streamer);
 
    privateInfo->archive_streamer = streamer;
 
    /*
     * Allocate a buffer for reading the archive file to facilitate content
     * decoding; read requests must not exceed the allocated buffer size.
     */
    privateInfo->archive_read_buf = pg_malloc(READ_CHUNK_SIZE);
 
#ifdef USE_ASSERT_CHECKING
    privateInfo->archive_read_buf_size = READ_CHUNK_SIZE;
#endif
 
    /*
     * Hash table storing WAL entries read from the archive with an arbitrary
     * initial size.
     */
    privateInfo->archive_wal_htab = ArchivedWAL_create(8, NULL);
 
    /*
     * Read until we have at least one full WAL page (XLOG_BLCKSZ bytes) from
     * the first WAL segment in the archive so we can extract the WAL segment
     * size from the long page header.
     */
    while (entry == NULL || entry->buf->len < XLOG_BLCKSZ)
    {
        if (read_archive_file(privateInfo, XLOG_BLCKSZ) == 0)
            pg_fatal("could not find WAL in archive \"%s\"",
                     privateInfo->archive_name);
 
        entry = privateInfo->cur_file;
    }
 
    /* Extract the WAL segment size from the long page header */
    longhdr = (XLogLongPageHeader) entry->buf->data;
 
    if (!IsValidWalSegSize(longhdr->xlp_seg_size))
    {
        pg_log_error(ngettext("invalid WAL segment size in WAL file from archive \"%s\" (%d byte)",
                              "invalid WAL segment size in WAL file from archive \"%s\" (%d bytes)",
                              longhdr->xlp_seg_size),
                     privateInfo->archive_name, longhdr->xlp_seg_size);
        pg_log_error_detail("The WAL segment size must be a power of two between 1 MB and 1 GB.");
        exit(1);
    }
 
    privateInfo->segsize = longhdr->xlp_seg_size;
 
    /*
     * With the WAL segment size available, we can now initialize the
     * dependent start and end segment numbers.
     */
    Assert(!XLogRecPtrIsInvalid(privateInfo->startptr));
    XLByteToSeg(privateInfo->startptr, privateInfo->start_segno,
                privateInfo->segsize);
 
    if (!XLogRecPtrIsInvalid(privateInfo->endptr))
        XLByteToSeg(privateInfo->endptr, privateInfo->end_segno,
                    privateInfo->segsize);
 
    /*
     * This WAL record was fetched before the filtering parameters
     * (start_segno and end_segno) were fully initialized. Perform the
     * relevance check against the user-provided range now; if the WAL falls
     * outside this range, remove it from the hash table. Subsequent WAL will
     * be filtered automatically by the archive streamer using the updated
     * start_segno and end_segno values.
     */
    XLogFromFileName(entry->fname, &timeline, &segno, privateInfo->segsize);
    if (privateInfo->timeline != timeline ||
        privateInfo->start_segno > segno ||
        privateInfo->end_segno < segno)
        free_archive_wal_entry(entry->fname, privateInfo);
}

References XLogDumpPrivate::archive_dir, XLogDumpPrivate::archive_fd, XLogDumpPrivate::archive_name, XLogDumpPrivate::archive_read_buf, XLogDumpPrivate::archive_streamer, XLogDumpPrivate::archive_wal_htab, Assert, astreamer_gzip_decompressor_new(), astreamer_lz4_decompressor_new(), astreamer_tar_parser_new(), astreamer_waldump_new(), astreamer_zstd_decompressor_new(), ArchivedWALFile::buf, XLogDumpPrivate::cur_file, StringInfoData::data, XLogDumpPrivate::end_segno, XLogDumpPrivate::endptr, fb(), fd(), ArchivedWALFile::fname, free_archive_wal_entry(), IsValidWalSegSize, StringInfoData::len, ngettext, open_file_in_directory(), PG_COMPRESSION_GZIP, PG_COMPRESSION_LZ4, PG_COMPRESSION_ZSTD, pg_fatal, pg_log_error, pg_log_error_detail, pg_malloc(), read_archive_file(), READ_CHUNK_SIZE, XLogDumpPrivate::segsize, XLogDumpPrivate::start_segno, XLogDumpPrivate::startptr, XLogDumpPrivate::timeline, XLByteToSeg, XLogFromFileName(), and XLogRecPtrIsInvalid.

Referenced by main().

member_is_wal_file()

static bool member_is_wal_file ( astreamer_waldump *  mystreamer, astreamer_member *  member, char **  fname  )

static

Definition at line 812 of file archive_waldump.c.

{
    int         pathlen;
    char        pathname[MAXPGPATH];
    char       *filename;
 
    /* We are only interested in normal files */
    if (member->is_directory || member->is_link)
        return false;
 
    if (strlen(member->pathname) < XLOG_FNAME_LEN)
        return false;
 
    /*
     * For a correct comparison, we must remove any '.' or '..' components
     * from the member pathname. Similar to member_verify_header(), we prepend
     * './' to the path so that canonicalize_path() can properly resolve and
     * strip these references from the tar member name.
     */
    snprintf(pathname, MAXPGPATH, "./%s", member->pathname);
    canonicalize_path(pathname);
    pathlen = strlen(pathname);
 
    /* Skip files in subdirectories other than pg_wal/ */
    if (pathlen > XLOG_FNAME_LEN &&
        strncmp(pathname, XLOGDIR, strlen(XLOGDIR)) != 0)
        return false;
 
    /* WAL file may appear with a full path (e.g., pg_wal/<name>) */
    filename = pathname + (pathlen - XLOG_FNAME_LEN);
    if (!IsXLogFileName(filename))
        return false;
 
    *fname = pnstrdup(filename, XLOG_FNAME_LEN);
 
    return true;
}

References canonicalize_path(), fb(), filename, astreamer_member::is_directory, astreamer_member::is_link, IsXLogFileName(), MAXPGPATH, astreamer_member::pathname, pnstrdup(), snprintf, XLOG_FNAME_LEN, and XLOGDIR.

Referenced by astreamer_waldump_content().

perform_tmp_write()

static void perform_tmp_write ( const char *  fname, StringInfo  buf, FILE *  file  )

static

Definition at line 653 of file archive_waldump.c.

{
    Assert(file);
 
    errno = 0;
    if (buf->len > 0 && fwrite(buf->data, buf->len, 1, file) != 1)
    {
        /*
         * If write didn't set errno, assume problem is no disk space
         */
        if (errno == 0)
            errno = ENOSPC;
        pg_fatal("could not write to file \"%s/%s\": %m", TmpWalSegDir, fname);
    }
}

References Assert, buf, fb(), pg_fatal, and TmpWalSegDir.

Referenced by get_archive_wal_entry().

prepare_tmp_write()

static FILE * prepare_tmp_write ( const char *  fname, XLogDumpPrivate *  privateInfo  )

static

Definition at line 616 of file archive_waldump.c.

{
    char        fpath[MAXPGPATH];
    FILE       *file;
 
    /*
     * Setup temporary directory to store WAL segments and set up an exit
     * callback to remove it upon completion if not already.
     */
    if (unlikely(TmpWalSegDir == NULL))
    {
        setup_tmpwal_dir(privateInfo->archive_dir);
        atexit(cleanup_tmpwal_dir_atexit);
    }
 
    snprintf(fpath, MAXPGPATH, "%s/%s", TmpWalSegDir, fname);
 
    /* Open the spill file for writing */
    file = fopen(fpath, PG_BINARY_W);
    if (file == NULL)
        pg_fatal("could not create file \"%s\": %m", fpath);
 
#ifndef WIN32
    if (chmod(fpath, pg_file_create_mode))
        pg_fatal("could not set permissions on file \"%s\": %m",
                 fpath);
#endif
 
    pg_log_debug("spilling to temporary file \"%s\"", fpath);
 
    return file;
}

References XLogDumpPrivate::archive_dir, cleanup_tmpwal_dir_atexit(), fb(), MAXPGPATH, PG_BINARY_W, pg_fatal, pg_file_create_mode, pg_log_debug, setup_tmpwal_dir(), snprintf, TmpWalSegDir, and unlikely.

Referenced by get_archive_wal_entry().

read_archive_file()

static int read_archive_file ( XLogDumpPrivate *  privateInfo, Size  count  )

static

Definition at line 545 of file archive_waldump.c.

{
    int         rc;
 
    /* The read request must not exceed the allocated buffer size. */
    Assert(privateInfo->archive_read_buf_size >= count);
 
    rc = read(privateInfo->archive_fd, privateInfo->archive_read_buf, count);
    if (rc < 0)
        pg_fatal("could not read file \"%s\": %m",
                 privateInfo->archive_name);
 
    /*
     * Decompress (if required), and then parse the previously read contents
     * of the tar file.
     */
    if (rc > 0)
        astreamer_content(privateInfo->archive_streamer, NULL,
                          privateInfo->archive_read_buf, rc,
                          ASTREAMER_UNKNOWN);
 
    return rc;
}

References XLogDumpPrivate::archive_fd, XLogDumpPrivate::archive_name, XLogDumpPrivate::archive_read_buf, XLogDumpPrivate::archive_streamer, Assert, astreamer_content(), ASTREAMER_UNKNOWN, fb(), pg_fatal, and read.

Referenced by get_archive_wal_entry(), init_archive_reader(), and read_archive_wal_page().

read_archive_wal_page()

int read_archive_wal_page	(	XLogDumpPrivate *	privateInfo,
		XLogRecPtr	targetPagePtr,
		Size	count,
		char *	readBuff
	)

Definition at line 281 of file archive_waldump.c.

{
    char       *p = readBuff;
    Size        nbytes = count;
    XLogRecPtr  recptr = targetPagePtr;
    int         segsize = privateInfo->segsize;
    XLogSegNo   segno;
    char        fname[MAXFNAMELEN];
    ArchivedWALFile *entry;
 
    /* Identify the segment and locate its entry in the archive hash */
    XLByteToSeg(targetPagePtr, segno, segsize);
    XLogFileName(fname, privateInfo->timeline, segno, segsize);
    entry = get_archive_wal_entry(fname, privateInfo);
 
    while (nbytes > 0)
    {
        char       *buf = entry->buf->data;
        int         bufLen = entry->buf->len;
        XLogRecPtr  endPtr;
        XLogRecPtr  startPtr;
 
        /*
         * Calculate the LSN range currently residing in the buffer.
         *
         * read_len tracks total bytes received for this segment (including
         * already-discarded data), so endPtr is the LSN just past the last
         * buffered byte, and startPtr is the LSN of the first buffered byte.
         */
        XLogSegNoOffsetToRecPtr(segno, entry->read_len, segsize, endPtr);
        startPtr = endPtr - bufLen;
 
        /*
         * Copy the requested WAL record if it exists in the buffer.
         */
        if (bufLen > 0 && startPtr <= recptr && recptr < endPtr)
        {
            int         copyBytes;
            int         offset = recptr - startPtr;
 
            /*
             * Given startPtr <= recptr < endPtr and a total buffer size
             * 'bufLen', the offset (recptr - startPtr) will always be less
             * than 'bufLen'.
             */
            Assert(offset < bufLen);
 
            copyBytes = Min(nbytes, bufLen - offset);
            memcpy(p, buf + offset, copyBytes);
 
            /* Update state for read */
            recptr += copyBytes;
            nbytes -= copyBytes;
            p += copyBytes;
        }
        else
        {
            /*
             * Before starting the actual decoding loop, pg_waldump tries to
             * locate the first valid record from the user-specified start
             * position, which might not be the start of a WAL record and
             * could fall in the middle of a record that spans multiple pages.
             * Consequently, the valid start position the decoder is looking
             * for could be far away from that initial position.
             *
             * This may involve reading across multiple pages, and this
             * pre-reading fetches data in multiple rounds from the archive
             * streamer; normally, we would throw away existing buffer
             * contents to fetch the next set of data, but that existing data
             * might be needed once the main loop starts. Because previously
             * read data cannot be re-read by the archive streamer, we delay
             * resetting the buffer until the main decoding loop is entered.
             *
             * Once pg_waldump has entered the main loop, it may re-read the
             * currently active page, but never an older one; therefore, any
             * fully consumed WAL data preceding the current page can then be
             * safely discarded.
             */
            if (privateInfo->decoding_started)
            {
                resetStringInfo(entry->buf);
 
                /*
                 * Push back the partial page data for the current page to the
                 * buffer, ensuring a full page remains available for
                 * re-reading if requested.
                 */
                if (p > readBuff)
                {
                    Assert((count - nbytes) > 0);
                    appendBinaryStringInfo(entry->buf, readBuff, count - nbytes);
                }
            }
 
            /*
             * Now, fetch more data.  Raise an error if the archive streamer
             * has moved past our segment (meaning the WAL file in the archive
             * is shorter than expected) or if reading the archive reached
             * EOF.
             */
            if (privateInfo->cur_file != entry)
                pg_fatal("WAL segment \"%s\" in archive \"%s\" is too short: read %lld of %lld bytes",
                         fname, privateInfo->archive_name,
                         (long long int) (count - nbytes),
                         (long long int) count);
            if (read_archive_file(privateInfo, READ_CHUNK_SIZE) == 0)
                pg_fatal("unexpected end of archive \"%s\" while reading \"%s\": read %lld of %lld bytes",
                         privateInfo->archive_name, fname,
                         (long long int) (count - nbytes),
                         (long long int) count);
        }
    }
 
    /*
     * Should have successfully read all the requested bytes or reported a
     * failure before this point.
     */
    Assert(nbytes == 0);
 
    /*
     * Return count unchanged; the caller expects this convention, matching
     * the routine that reads WAL pages from physical files.
     */
    return count;
}

References appendBinaryStringInfo(), XLogDumpPrivate::archive_name, Assert, buf, ArchivedWALFile::buf, XLogDumpPrivate::cur_file, StringInfoData::data, XLogDumpPrivate::decoding_started, fb(), get_archive_wal_entry(), StringInfoData::len, MAXFNAMELEN, Min, pg_fatal, read_archive_file(), READ_CHUNK_SIZE, ArchivedWALFile::read_len, resetStringInfo(), XLogDumpPrivate::segsize, XLogDumpPrivate::timeline, XLByteToSeg, XLogFileName(), and XLogSegNoOffsetToRecPtr.

Referenced by TarWALDumpReadPage().

setup_tmpwal_dir()

static void setup_tmpwal_dir ( const char *  waldir )

static

Definition at line 573 of file archive_waldump.c.

{
    const char *tmpdir = getenv("TMPDIR");
    char       *template;
 
    Assert(TmpWalSegDir == NULL);
 
    /*
     * Use the directory specified by the TMPDIR environment variable. If it's
     * not set, fall back to the provided WAL directory to store WAL files
     * temporarily.
     */
    template = psprintf("%s/waldump_tmp-XXXXXX",
                        tmpdir ? tmpdir : waldir);
    TmpWalSegDir = mkdtemp(template);
 
    if (TmpWalSegDir == NULL)
        pg_fatal("could not create directory \"%s\": %m", template);
 
    canonicalize_path(TmpWalSegDir);
 
    pg_log_debug("created directory \"%s\"", TmpWalSegDir);
}

References Assert, canonicalize_path(), fb(), mkdtemp(), pg_fatal, pg_log_debug, psprintf(), and TmpWalSegDir.

Referenced by prepare_tmp_write().

Variable Documentation

astreamer_waldump_ops

const astreamer_ops astreamer_waldump_ops

static

Initial value:

= {
    .content = astreamer_waldump_content,
    .finalize = astreamer_waldump_finalize,
    .free = astreamer_waldump_free
}

Definition at line 111 of file archive_waldump.c.

                                                   {
    .content = astreamer_waldump_content,
    .finalize = astreamer_waldump_finalize,
    .free = astreamer_waldump_free
};

Referenced by astreamer_waldump_new().

TmpWalSegDir

char* TmpWalSegDir = NULL

Definition at line 32 of file archive_waldump.c.

Referenced by cleanup_tmpwal_dir_atexit(), free_archive_wal_entry(), perform_tmp_write(), prepare_tmp_write(), setup_tmpwal_dir(), and TarWALDumpReadPage().