/*
* Copy a file from source to target, between 'begin' and 'end' offsets.
*/
static void
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)
{
fprintf(stderr, "could not open source file \"%s\": %s\n", srcpath, strerror(errno));
exit(1);
}
if (lseek(srcfd, begin, SEEK_SET) == -1)
{
fprintf(stderr, "could not seek in source file: %s\n", strerror(errno));
exit(1);
}
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)
{
fprintf(stderr, "could not read file \"%s\": %s\n", srcpath, strerror(errno));
exit(1);
}
else if (readlen == 0)
{
fprintf(stderr, "unexpected EOF while reading file \"%s\"\n", srcpath);
exit(1);
}
write_file_range(buf, begin, readlen);
begin += readlen;
}
}
/*
* 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)
{
PGAlignedBlock buf;
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\": %m",
srcpath);
if (lseek(srcfd, begin, SEEK_SET) == -1)
pg_fatal("could not seek in source file: %m");
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.data, len);
if (readlen < 0)
pg_fatal("could not read file \"%s\": %m",
srcpath);
else if (readlen == 0)
pg_fatal("unexpected EOF while reading file \"%s\"", srcpath);
write_target_range(buf.data, begin, readlen);
begin += readlen;
}
if (close(srcfd) != 0)
pg_fatal("could not close file \"%s\": %m", srcpath);
}
/*
* Fetch all changed blocks from remote source data directory.
*/
void
libpq_executeFileMap(filemap_t *map)
{
file_entry_t *entry;
const char *sql;
PGresult *res;
int i;
/*
* First create a temporary table, and load it with the blocks that we
* need to fetch.
*/
sql = "CREATE TEMPORARY TABLE fetchchunks(path text, begin int8, len int4);";
res = PQexec(conn, sql);
if (PQresultStatus(res) != PGRES_COMMAND_OK)
pg_fatal("could not create temporary table: %s",
PQresultErrorMessage(res));
PQclear(res);
sql = "COPY fetchchunks FROM STDIN";
res = PQexec(conn, sql);
if (PQresultStatus(res) != PGRES_COPY_IN)
pg_fatal("could not send file list: %s",
PQresultErrorMessage(res));
PQclear(res);
for (i = 0; i < map->narray; i++)
{
entry = map->array[i];
/* If this is a relation file, copy the modified blocks */
execute_pagemap(&entry->pagemap, entry->path);
switch (entry->action)
{
case FILE_ACTION_NONE:
/* nothing else to do */
break;
case FILE_ACTION_COPY:
/* Truncate the old file out of the way, if any */
open_target_file(entry->path, true);
fetch_file_range(entry->path, 0, entry->newsize);
break;
case FILE_ACTION_TRUNCATE:
truncate_target_file(entry->path, entry->newsize);
break;
case FILE_ACTION_COPY_TAIL:
fetch_file_range(entry->path, entry->oldsize, entry->newsize);
break;
case FILE_ACTION_REMOVE:
remove_target(entry);
break;
case FILE_ACTION_CREATE:
create_target(entry);
break;
}
}
if (PQputCopyEnd(conn, NULL) != 1)
pg_fatal("could not send end-of-COPY: %s",
PQerrorMessage(conn));
while ((res = PQgetResult(conn)) != NULL)
{
if (PQresultStatus(res) != PGRES_COMMAND_OK)
pg_fatal("unexpected result while sending file list: %s",
PQresultErrorMessage(res));
PQclear(res);
}
/*
* We've now copied the list of file ranges that we need to fetch to the
* temporary table. Now, actually fetch all of those ranges.
*/
sql =
"SELECT path, begin, \n"
" pg_read_binary_file(path, begin, len, true) AS chunk\n"
"FROM fetchchunks\n";
receiveFileChunks(sql);
}
/*----
* 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);
}
}
/*
* Fetch all changed blocks from remote source data directory.
*/
void
libpq_executeFileMap(filemap_t *map)
{
file_entry_t *entry;
const char *sql;
PGresult *res;
/*
* First create a temporary table, and load it with the blocks that
* we need to fetch.
*/
sql = "create temporary table fetchchunks(path text, begin int4, len int4);";
res = PQexec(conn, sql);
if (PQresultStatus(res) != PGRES_COMMAND_OK)
{
fprintf(stderr, "error creating temporary table: %s\n",
PQresultErrorMessage(res));
exit(1);
}
sql = "copy fetchchunks from stdin";
res = PQexec(conn, sql);
if (PQresultStatus(res) != PGRES_COPY_IN)
{
fprintf(stderr, "unexpected result while sending file list: %s\n",
PQresultErrorMessage(res));
exit(1);
}
for (entry = map->first; entry != NULL; entry = entry->next)
{
execute_pagemap(&entry->pagemap, entry->path);
switch (entry->action)
{
case FILE_ACTION_NONE:
/* ok, do nothing.. */
break;
case FILE_ACTION_COPY:
/* Truncate the old file out of the way, if any */
open_target_file(entry->path, true);
copy_file_range(entry->path, 0, entry->newsize);
break;
case FILE_ACTION_REMOVE:
remove_target_file(entry->path);
break;
case FILE_ACTION_TRUNCATE:
truncate_target_file(entry->path, entry->newsize);
break;
case FILE_ACTION_COPY_TAIL:
copy_file_range(entry->path, entry->oldsize, entry->newsize);
break;
case FILE_ACTION_CREATEDIR:
create_target_dir(entry->path);
break;
case FILE_ACTION_REMOVEDIR:
remove_target_dir(entry->path);
break;
}
}
if (PQputCopyEnd(conn, NULL) != 1)
{
fprintf(stderr, "error sending end-of-COPY: %s\n",
PQerrorMessage(conn));
exit(1);
}
while ((res = PQgetResult(conn)) != NULL)
{
if (PQresultStatus(res) != PGRES_COMMAND_OK)
{
fprintf(stderr, "unexpected result while sending file list: %s\n",
PQresultErrorMessage(res));
exit(1);
}
}
/* Ok, we've sent the file list. Now receive the files */
sql =
"-- fetch all the blocks listed in the temp table.\n"
"select path, begin, \n"
" pg_read_binary_file(path, begin, len) as chunk\n"
"from fetchchunks\n";
receiveFileChunks(sql);
}
/*
* 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)
{
fprintf(stderr, "could not send query: %s\n", PQerrorMessage(conn));
exit(1);
}
if (verbose)
fprintf(stderr, "getting chunks: %s\n", sql);
if (PQsetSingleRowMode(conn) != 1)
{
fprintf(stderr, "could not set libpq connection to single row mode\n");
exit(1);
}
if (verbose)
fprintf(stderr, "sent query\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:
continue; /* final zero-row result */
default:
fprintf(stderr, "unexpected result while fetching remote files: %s\n",
PQresultErrorMessage(res));
exit(1);
}
/* sanity check the result set */
if (!(PQnfields(res) == 3 && PQntuples(res) == 1))
{
fprintf(stderr, "unexpected result set size while fetching remote files\n");
exit(1);
}
if (!(PQftype(res, 0) == TEXTOID && PQftype(res, 1) == INT4OID && PQftype(res, 2) == BYTEAOID))
{
fprintf(stderr, "unexpected data types in result set while fetching remote files: %u %u %u\n", PQftype(res, 0), PQftype(res, 1), PQftype(res, 2));
exit(1);
}
if (!(PQfformat(res, 0) == 1 && PQfformat(res, 1) == 1 && PQfformat(res, 2) == 1))
{
fprintf(stderr, "unexpected result format while fetching remote files\n");
exit(1);
}
if (!(!PQgetisnull(res, 0, 0) && !PQgetisnull(res, 0, 1) && !PQgetisnull(res, 0, 2) &&
PQgetlength(res, 0, 1) == sizeof(int32)))
{
fprintf(stderr, "unexpected result set while fetching remote files\n");
exit(1);
}
/* 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);
if (verbose)
fprintf(stderr, "received chunk for file \"%s\", off %d, len %d\n",
filename, chunkoff, chunksize);
open_target_file(filename, false);
write_file_range(chunk, chunkoff, chunksize);
}
}
