snapbuild_internal.h File Reference

#include "port/pg_crc32c.h"
#include "replication/reorderbuffer.h"
#include "replication/snapbuild.h"

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Data Structures
struct	SnapBuild
struct	SnapBuildOnDisk

Typedefs
typedef struct SnapBuildOnDisk	SnapBuildOnDisk

Functions
bool	SnapBuildRestoreSnapshot (SnapBuildOnDisk *ondisk, XLogRecPtr lsn, MemoryContext context, bool missing_ok)

Typedef Documentation

SnapBuildOnDisk

typedef struct SnapBuildOnDisk SnapBuildOnDisk

Function Documentation

SnapBuildRestoreSnapshot()

bool SnapBuildRestoreSnapshot ( SnapBuildOnDisk *  ondisk, XLogRecPtr  lsn, MemoryContext  context, bool  missing_ok  )

extern

Definition at line 1745 of file snapbuild.c.

{
    int         fd;
    pg_crc32c   checksum;
    Size        sz;
    char        path[MAXPGPATH];
 
    sprintf(path, "%s/%X-%X.snap",
            PG_LOGICAL_SNAPSHOTS_DIR,
            LSN_FORMAT_ARGS(lsn));
 
    fd = OpenTransientFile(path, O_RDONLY | PG_BINARY);
 
    if (fd < 0)
    {
        if (missing_ok && errno == ENOENT)
            return false;
 
        ereport(ERROR,
                (errcode_for_file_access(),
                 errmsg("could not open file \"%s\": %m", path)));
    }
 
    /* ----
     * Make sure the snapshot had been stored safely to disk, that's normally
     * cheap.
     * Note that we do not need PANIC here, nobody will be able to use the
     * slot without fsyncing, and saving it won't succeed without an fsync()
     * either...
     * ----
     */
    fsync_fname(path, false);
    fsync_fname(PG_LOGICAL_SNAPSHOTS_DIR, true);
 
    /* read statically sized portion of snapshot */
    SnapBuildRestoreContents(fd, ondisk, SnapBuildOnDiskConstantSize, path);
 
    if (ondisk->magic != SNAPBUILD_MAGIC)
        ereport(ERROR,
                (errcode(ERRCODE_DATA_CORRUPTED),
                 errmsg("snapbuild state file \"%s\" has wrong magic number: %u instead of %u",
                        path, ondisk->magic, SNAPBUILD_MAGIC)));
 
    if (ondisk->version != SNAPBUILD_VERSION)
        ereport(ERROR,
                (errcode(ERRCODE_DATA_CORRUPTED),
                 errmsg("snapbuild state file \"%s\" has unsupported version: %u instead of %u",
                        path, ondisk->version, SNAPBUILD_VERSION)));
 
    INIT_CRC32C(checksum);
    COMP_CRC32C(checksum,
                ((char *) ondisk) + SnapBuildOnDiskNotChecksummedSize,
                SnapBuildOnDiskConstantSize - SnapBuildOnDiskNotChecksummedSize);
 
    /* read SnapBuild */
    SnapBuildRestoreContents(fd, &ondisk->builder, sizeof(SnapBuild), path);
    COMP_CRC32C(checksum, &ondisk->builder, sizeof(SnapBuild));
 
    /* restore committed xacts information */
    if (ondisk->builder.committed.xcnt > 0)
    {
        sz = sizeof(TransactionId) * ondisk->builder.committed.xcnt;
        ondisk->builder.committed.xip = MemoryContextAllocZero(context, sz);
        SnapBuildRestoreContents(fd, ondisk->builder.committed.xip, sz, path);
        COMP_CRC32C(checksum, ondisk->builder.committed.xip, sz);
    }
 
    /* restore catalog modifying xacts information */
    if (ondisk->builder.catchange.xcnt > 0)
    {
        sz = sizeof(TransactionId) * ondisk->builder.catchange.xcnt;
        ondisk->builder.catchange.xip = MemoryContextAllocZero(context, sz);
        SnapBuildRestoreContents(fd, ondisk->builder.catchange.xip, sz, path);
        COMP_CRC32C(checksum, ondisk->builder.catchange.xip, sz);
    }
 
    if (CloseTransientFile(fd) != 0)
        ereport(ERROR,
                (errcode_for_file_access(),
                 errmsg("could not close file \"%s\": %m", path)));
 
    FIN_CRC32C(checksum);
 
    /* verify checksum of what we've read */
    if (!EQ_CRC32C(checksum, ondisk->checksum))
        ereport(ERROR,
                (errcode(ERRCODE_DATA_CORRUPTED),
                 errmsg("checksum mismatch for snapbuild state file \"%s\": is %u, should be %u",
                        path, checksum, ondisk->checksum)));
 
    return true;
}

References SnapBuildOnDisk::builder, SnapBuild::catchange, SnapBuildOnDisk::checksum, CloseTransientFile(), SnapBuild::committed, COMP_CRC32C, EQ_CRC32C, ereport, errcode(), ERRCODE_DATA_CORRUPTED, errcode_for_file_access(), errmsg, ERROR, fb(), fd(), FIN_CRC32C, fsync_fname(), INIT_CRC32C, LSN_FORMAT_ARGS, SnapBuildOnDisk::magic, MAXPGPATH, MemoryContextAllocZero(), OpenTransientFile(), PG_BINARY, PG_LOGICAL_SNAPSHOTS_DIR, SNAPBUILD_MAGIC, SNAPBUILD_VERSION, SnapBuildOnDiskConstantSize, SnapBuildOnDiskNotChecksummedSize, SnapBuildRestoreContents(), sprintf, SnapBuildOnDisk::version, SnapBuild::xcnt, and SnapBuild::xip.

Referenced by pg_get_logical_snapshot_info(), pg_get_logical_snapshot_meta(), and SnapBuildRestore().