/*
* Copy a file from source to target, between 'begin' and 'end' offsets.
*
* If 'trunc' is true, any existing file with the same name is truncated.
*/
static void
rewind_copy_file_range(const char *path, off_t begin, off_t end, bool trunc)
{
char buf[BLCKSZ];
char srcpath[MAXPGPATH];
int srcfd;
snprintf(srcpath, sizeof(srcpath), "%s/%s", datadir_source, path);
srcfd = open(srcpath, O_RDONLY | PG_BINARY, 0);
if (srcfd < 0)
pg_fatal("could not open source file \"%s\": %s\n",
srcpath, strerror(errno));
if (lseek(srcfd, begin, SEEK_SET) == -1)
pg_fatal("could not seek in source file: %s\n", strerror(errno));
open_target_file(path, trunc);
while (end - begin > 0)
{
int readlen;
int len;
if (end - begin > sizeof(buf))
len = sizeof(buf);
else
len = end - begin;
readlen = read(srcfd, buf, len);
if (readlen < 0)
pg_fatal("could not read file \"%s\": %s\n",
srcpath, strerror(errno));
else if (readlen == 0)
pg_fatal("unexpected EOF while reading file \"%s\"\n", srcpath);
write_target_range(buf, begin, readlen);
begin += readlen;
}
if (close(srcfd) != 0)
pg_fatal("could not close file \"%s\": %s\n", srcpath, strerror(errno));
}
/*----
* Runs a query, which returns pieces of files from the remote source data
* directory, and overwrites the corresponding parts of target files with
* the received parts. The result set is expected to be of format:
*
* path text -- path in the data directory, e.g "base/1/123"
* begin int8 -- offset within the file
* chunk bytea -- file content
*----
*/
static void
receiveFileChunks(const char *sql)
{
PGresult *res;
if (PQsendQueryParams(conn, sql, 0, NULL, NULL, NULL, NULL, 1) != 1)
pg_fatal("could not send query: %s", PQerrorMessage(conn));
pg_log(PG_DEBUG, "getting file chunks\n");
if (PQsetSingleRowMode(conn) != 1)
pg_fatal("could not set libpq connection to single row mode\n");
while ((res = PQgetResult(conn)) != NULL)
{
char *filename;
int filenamelen;
int64 chunkoff;
char chunkoff_str[32];
int chunksize;
char *chunk;
switch (PQresultStatus(res))
{
case PGRES_SINGLE_TUPLE:
break;
case PGRES_TUPLES_OK:
PQclear(res);
continue; /* final zero-row result */
default:
pg_fatal("unexpected result while fetching remote files: %s",
PQresultErrorMessage(res));
}
/* sanity check the result set */
if (PQnfields(res) != 3 || PQntuples(res) != 1)
pg_fatal("unexpected result set size while fetching remote files\n");
if (PQftype(res, 0) != TEXTOID ||
PQftype(res, 1) != INT8OID ||
PQftype(res, 2) != BYTEAOID)
{
pg_fatal("unexpected data types in result set while fetching remote files: %u %u %u\n",
PQftype(res, 0), PQftype(res, 1), PQftype(res, 2));
}
if (PQfformat(res, 0) != 1 &&
PQfformat(res, 1) != 1 &&
PQfformat(res, 2) != 1)
{
pg_fatal("unexpected result format while fetching remote files\n");
}
if (PQgetisnull(res, 0, 0) ||
PQgetisnull(res, 0, 1))
{
pg_fatal("unexpected null values in result while fetching remote files\n");
}
if (PQgetlength(res, 0, 1) != sizeof(int64))
pg_fatal("unexpected result length while fetching remote files\n");
/* Read result set to local variables */
memcpy(&chunkoff, PQgetvalue(res, 0, 1), sizeof(int64));
chunkoff = pg_recvint64(chunkoff);
chunksize = PQgetlength(res, 0, 2);
filenamelen = PQgetlength(res, 0, 0);
filename = pg_malloc(filenamelen + 1);
memcpy(filename, PQgetvalue(res, 0, 0), filenamelen);
filename[filenamelen] = '\0';
chunk = PQgetvalue(res, 0, 2);
/*
* If a file has been deleted on the source, remove it on the target
* as well. Note that multiple unlink() calls may happen on the same
* file if multiple data chunks are associated with it, hence ignore
* unconditionally anything missing. If this file is not a relation
* data file, then it has been already truncated when creating the
* file chunk list at the previous execution of the filemap.
*/
if (PQgetisnull(res, 0, 2))
{
pg_log(PG_DEBUG,
"received null value for chunk for file \"%s\", file has been deleted\n",
filename);
remove_target_file(filename, true);
pg_free(filename);
PQclear(res);
continue;
}
/*
* Separate step to keep platform-dependent format code out of
* translatable strings.
*/
snprintf(chunkoff_str, sizeof(chunkoff_str), INT64_FORMAT, chunkoff);
pg_log(PG_DEBUG, "received chunk for file \"%s\", offset %s, size %d\n",
filename, chunkoff_str, chunksize);
open_target_file(filename, false);
write_target_range(chunk, chunkoff, chunksize);
pg_free(filename);
PQclear(res);
}
}
/*----
* Runs a query, which returns pieces of files from the remote source data
* directory, and overwrites the corresponding parts of target files with
* the received parts. The result set is expected to be of format:
*
* path text -- path in the data directory, e.g "base/1/123"
* begin int4 -- offset within the file
* chunk bytea -- file content
*----
*/
static void
receiveFileChunks(const char *sql)
{
PGresult *res;
if (PQsendQueryParams(conn, sql, 0, NULL, NULL, NULL, NULL, 1) != 1)
pg_fatal("could not send query: %s", PQerrorMessage(conn));
pg_log(PG_DEBUG, "getting file chunks\n");
if (PQsetSingleRowMode(conn) != 1)
pg_fatal("could not set libpq connection to single row mode\n");
while ((res = PQgetResult(conn)) != NULL)
{
char *filename;
int filenamelen;
int chunkoff;
int chunksize;
char *chunk;
switch (PQresultStatus(res))
{
case PGRES_SINGLE_TUPLE:
break;
case PGRES_TUPLES_OK:
PQclear(res);
continue; /* final zero-row result */
default:
pg_fatal("unexpected result while fetching remote files: %s",
PQresultErrorMessage(res));
}
/* sanity check the result set */
if (PQnfields(res) != 3 || PQntuples(res) != 1)
pg_fatal("unexpected result set size while fetching remote files\n");
if (PQftype(res, 0) != TEXTOID &&
PQftype(res, 1) != INT4OID &&
PQftype(res, 2) != BYTEAOID)
{
pg_fatal("unexpected data types in result set while fetching remote files: %u %u %u\n",
PQftype(res, 0), PQftype(res, 1), PQftype(res, 2));
}
if (PQfformat(res, 0) != 1 &&
PQfformat(res, 1) != 1 &&
PQfformat(res, 2) != 1)
{
pg_fatal("unexpected result format while fetching remote files\n");
}
if (PQgetisnull(res, 0, 0) ||
PQgetisnull(res, 0, 1))
{
pg_fatal("unexpected null values in result while fetching remote files\n");
}
if (PQgetlength(res, 0, 1) != sizeof(int32))
pg_fatal("unexpected result length while fetching remote files\n");
/* Read result set to local variables */
memcpy(&chunkoff, PQgetvalue(res, 0, 1), sizeof(int32));
chunkoff = ntohl(chunkoff);
chunksize = PQgetlength(res, 0, 2);
filenamelen = PQgetlength(res, 0, 0);
filename = pg_malloc(filenamelen + 1);
memcpy(filename, PQgetvalue(res, 0, 0), filenamelen);
filename[filenamelen] = '\0';
chunk = PQgetvalue(res, 0, 2);
/*
* It's possible that the file was deleted on remote side after we
* created the file map. In this case simply ignore it, as if it was
* not there in the first place, and move on.
*/
if (PQgetisnull(res, 0, 2))
{
pg_log(PG_DEBUG,
"received null value for chunk for file \"%s\", file has been deleted\n",
filename);
pg_free(filename);
PQclear(res);
continue;
}
pg_log(PG_DEBUG, "received chunk for file \"%s\", offset %d, size %d\n",
filename, chunkoff, chunksize);
open_target_file(filename, false);
write_target_range(chunk, chunkoff, chunksize);
pg_free(filename);
PQclear(res);
}
}
