On 06.06.2018 02:03, Thomas Munro wrote:
On Wed, Jun 6, 2018 at 2:06 AM, Konstantin Knizhnik
<k.knizh...@postgrespro.ru> wrote:
Thank you for review. Updated version of the patch fixing all reported
problems is attached.
Small problem on Windows[1]:
C:\projects\postgresql\src\include\common/zpq_stream.h(17): error
C2143: syntax error : missing ')' before '*'
[C:\projects\postgresql\libpq.vcxproj]
2395
You used ssize_t in zpq_stream.h, but Windows doesn't have that type.
We have our own typedef in win32_port.h. Perhaps zpq_stream.c should
include postgres.h/postgres_fe.h (depending on FRONTEND) like the
other .c files in src/common, before it includes zpq_stream.h?
Instead of "c.h".
[1] https://ci.appveyor.com/project/postgresql-cfbot/postgresql/build/1.0.1106
Thank you very much for reporting the problem.
I attached new patch with include of postgres_fe.h added to zpq_stream.c
--
Konstantin Knizhnik
Postgres Professional: http://www.postgrespro.com
The Russian Postgres Company
diff --git a/configure b/configure
index 0aafd9c..fc5685c 100755
--- a/configure
+++ b/configure
@@ -699,6 +699,7 @@ ELF_SYS
EGREP
GREP
with_zlib
+with_zstd
with_system_tzdata
with_libxslt
with_libxml
@@ -863,6 +864,7 @@ with_libxml
with_libxslt
with_system_tzdata
with_zlib
+with_zstd
with_gnu_ld
enable_largefile
enable_float4_byval
@@ -8017,6 +8019,86 @@ fi
#
+# ZStd
+#
+
+
+
+# Check whether --with-zstd was given.
+if test "${with_zstd+set}" = set; then :
+ withval=$with_zstd;
+ case $withval in
+ yes)
+ ;;
+ no)
+ :
+ ;;
+ *)
+ as_fn_error $? "no argument expected for --with-zstd option" "$LINENO" 5
+ ;;
+ esac
+
+else
+ with_zstd=no
+
+fi
+
+
+
+
+if test "$with_zstd" = yes ; then
+ { $as_echo "$as_me:${as_lineno-$LINENO}: checking for ZSTD_compress in -lzstd" >&5
+$as_echo_n "checking for ZSTD_compress in -lzstd... " >&6; }
+if ${ac_cv_lib_zstd_ZSTD_compress+:} false; then :
+ $as_echo_n "(cached) " >&6
+else
+ ac_check_lib_save_LIBS=$LIBS
+LIBS="-lzstd $LIBS"
+cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h. */
+
+/* Override any GCC internal prototype to avoid an error.
+ Use char because int might match the return type of a GCC
+ builtin and then its argument prototype would still apply. */
+#ifdef __cplusplus
+extern "C"
+#endif
+char ZSTD_compress ();
+int
+main ()
+{
+return ZSTD_compress ();
+ ;
+ return 0;
+}
+_ACEOF
+if ac_fn_c_try_link "$LINENO"; then :
+ ac_cv_lib_zstd_ZSTD_compress=yes
+else
+ ac_cv_lib_zstd_ZSTD_compress=no
+fi
+rm -f core conftest.err conftest.$ac_objext \
+ conftest$ac_exeext conftest.$ac_ext
+LIBS=$ac_check_lib_save_LIBS
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_lib_zstd_ZSTD_compress" >&5
+$as_echo "$ac_cv_lib_zstd_ZSTD_compress" >&6; }
+if test "x$ac_cv_lib_zstd_ZSTD_compress" = xyes; then :
+ cat >>confdefs.h <<_ACEOF
+#define HAVE_LIBZSTD 1
+_ACEOF
+
+ LIBS="-lzstd $LIBS"
+
+else
+ as_fn_error $? "library 'zstd' is required for ZSTD support" "$LINENO" 5
+fi
+
+fi
+
+
+
+#
# Elf
#
diff --git a/src/Makefile.global.in b/src/Makefile.global.in
index 95d090e..b59629c 100644
--- a/src/Makefile.global.in
+++ b/src/Makefile.global.in
@@ -196,6 +196,7 @@ with_llvm = @with_llvm@
with_system_tzdata = @with_system_tzdata@
with_uuid = @with_uuid@
with_zlib = @with_zlib@
+with_zstd = @with_zstd@
enable_rpath = @enable_rpath@
enable_nls = @enable_nls@
enable_debug = @enable_debug@
diff --git a/src/backend/Makefile b/src/backend/Makefile
index 25af514..a8e461a 100644
--- a/src/backend/Makefile
+++ b/src/backend/Makefile
@@ -51,6 +51,14 @@ ifeq ($(with_systemd),yes)
LIBS += -lsystemd
endif
+ifeq ($(with_zstd),yes)
+LIBS += -lzstd
+endif
+
+ifeq ($(with_zlib),yes)
+LIBS += -lz
+endif
+
##########################################################################
all: submake-libpgport submake-catalog-headers submake-utils-headers postgres $(POSTGRES_IMP)
diff --git a/src/backend/libpq/pqcomm.c b/src/backend/libpq/pqcomm.c
index a4f6d4d..c963657 100644
--- a/src/backend/libpq/pqcomm.c
+++ b/src/backend/libpq/pqcomm.c
@@ -95,6 +95,7 @@
#include "storage/ipc.h"
#include "utils/guc.h"
#include "utils/memutils.h"
+#include "common/zpq_stream.h"
/*
* Cope with the various platform-specific ways to spell TCP keepalive socket
@@ -143,6 +144,9 @@ static char PqRecvBuffer[PQ_RECV_BUFFER_SIZE];
static int PqRecvPointer; /* Next index to read a byte from PqRecvBuffer */
static int PqRecvLength; /* End of data available in PqRecvBuffer */
+static ZpqStream* PqStream;
+
+
/*
* Message status
*/
@@ -185,6 +189,31 @@ PQcommMethods *PqCommMethods = &PqCommSocketMethods;
WaitEventSet *FeBeWaitSet;
+/* --------------------------------
+ * pq_configure - configure connection using port settings
+ *
+ * Right now only conpression is toggled in the configure.
+ * Function returns 0 in case of success, non-null in case of error
+ * --------------------------------
+ */
+int
+pq_configure(Port* port)
+{
+ if (port->use_compression)
+ {
+ char compression = 'z'; /* Request compression message */
+ int rc;
+ /* Switch on compression at client side */
+ socket_set_nonblocking(false);
+ while ((rc = secure_write(MyProcPort, &compression, 1)) < 0 && errno == EINTR);
+ if (rc != 1)
+ return -1;
+
+ /* initialize compression */
+ PqStream = zpq_create((zpq_tx_func)secure_write, (zpq_rx_func)secure_read, MyProcPort);
+ }
+ return 0;
+}
/* --------------------------------
* pq_init - initialize libpq at backend startup
@@ -225,6 +254,7 @@ pq_init(void)
NULL, NULL);
AddWaitEventToSet(FeBeWaitSet, WL_LATCH_SET, -1, MyLatch, NULL);
AddWaitEventToSet(FeBeWaitSet, WL_POSTMASTER_DEATH, -1, NULL, NULL);
+
}
/* --------------------------------
@@ -282,6 +312,9 @@ socket_close(int code, Datum arg)
free(MyProcPort->gss);
#endif /* ENABLE_GSS || ENABLE_SSPI */
+ /* Release compression streams */
+ zpq_free(PqStream);
+
/*
* Cleanly shut down SSL layer. Nowhere else does a postmaster child
* call this, so this is safe when interrupting BackendInitialize().
@@ -932,12 +965,14 @@ socket_set_nonblocking(bool nonblocking)
/* --------------------------------
* pq_recvbuf - load some bytes into the input buffer
*
- * returns 0 if OK, EOF if trouble
+ * returns number of read bytes, EOF if trouble
* --------------------------------
*/
static int
-pq_recvbuf(void)
+pq_recvbuf(bool nowait)
{
+ int r;
+
if (PqRecvPointer > 0)
{
if (PqRecvLength > PqRecvPointer)
@@ -953,21 +988,37 @@ pq_recvbuf(void)
}
/* Ensure that we're in blocking mode */
- socket_set_nonblocking(false);
+ socket_set_nonblocking(nowait);
/* Can fill buffer from PqRecvLength and upwards */
for (;;)
{
- int r;
-
- r = secure_read(MyProcPort, PqRecvBuffer + PqRecvLength,
- PQ_RECV_BUFFER_SIZE - PqRecvLength);
+ size_t processed = 0;
+ r = PqStream
+ ? zpq_read(PqStream, PqRecvBuffer + PqRecvLength,
+ PQ_RECV_BUFFER_SIZE - PqRecvLength, &processed)
+ : secure_read(MyProcPort, PqRecvBuffer + PqRecvLength,
+ PQ_RECV_BUFFER_SIZE - PqRecvLength);
+ PqRecvLength += processed;
if (r < 0)
{
+ if (r == ZPQ_DECOMPRESS_ERROR)
+ {
+ char const* msg = zpq_error(PqStream);
+ if (msg == NULL)
+ msg = "end of stream";
+ ereport(COMMERROR,
+ (errcode_for_socket_access(),
+ errmsg("failed to decompress data: %s", msg)));
+ return EOF;
+ }
if (errno == EINTR)
continue; /* Ok if interrupted */
+ if (nowait && (errno == EAGAIN || errno == EWOULDBLOCK))
+ return 0;
+
/*
* Careful: an ereport() that tries to write to the client would
* cause recursion to here, leading to stack overflow and core
@@ -988,7 +1039,7 @@ pq_recvbuf(void)
}
/* r contains number of bytes read, so just incr length */
PqRecvLength += r;
- return 0;
+ return r;
}
}
@@ -1003,7 +1054,7 @@ pq_getbyte(void)
while (PqRecvPointer >= PqRecvLength)
{
- if (pq_recvbuf()) /* If nothing in buffer, then recv some */
+ if (pq_recvbuf(false) == EOF) /* If nothing in buffer, then recv some */
return EOF; /* Failed to recv data */
}
return (unsigned char) PqRecvBuffer[PqRecvPointer++];
@@ -1022,7 +1073,7 @@ pq_peekbyte(void)
while (PqRecvPointer >= PqRecvLength)
{
- if (pq_recvbuf()) /* If nothing in buffer, then recv some */
+ if (pq_recvbuf(false) == EOF) /* If nothing in buffer, then recv some */
return EOF; /* Failed to recv data */
}
return (unsigned char) PqRecvBuffer[PqRecvPointer];
@@ -1043,44 +1094,11 @@ pq_getbyte_if_available(unsigned char *c)
Assert(PqCommReadingMsg);
- if (PqRecvPointer < PqRecvLength)
+ if (PqRecvPointer < PqRecvLength || (r = pq_recvbuf(true)) > 0)
{
*c = PqRecvBuffer[PqRecvPointer++];
return 1;
}
-
- /* Put the socket into non-blocking mode */
- socket_set_nonblocking(true);
-
- r = secure_read(MyProcPort, c, 1);
- if (r < 0)
- {
- /*
- * Ok if no data available without blocking or interrupted (though
- * EINTR really shouldn't happen with a non-blocking socket). Report
- * other errors.
- */
- if (errno == EAGAIN || errno == EWOULDBLOCK || errno == EINTR)
- r = 0;
- else
- {
- /*
- * Careful: an ereport() that tries to write to the client would
- * cause recursion to here, leading to stack overflow and core
- * dump! This message must go *only* to the postmaster log.
- */
- ereport(COMMERROR,
- (errcode_for_socket_access(),
- errmsg("could not receive data from client: %m")));
- r = EOF;
- }
- }
- else if (r == 0)
- {
- /* EOF detected */
- r = EOF;
- }
-
return r;
}
@@ -1101,7 +1119,7 @@ pq_getbytes(char *s, size_t len)
{
while (PqRecvPointer >= PqRecvLength)
{
- if (pq_recvbuf()) /* If nothing in buffer, then recv some */
+ if (pq_recvbuf(false) == EOF) /* If nothing in buffer, then recv some */
return EOF; /* Failed to recv data */
}
amount = PqRecvLength - PqRecvPointer;
@@ -1135,7 +1153,7 @@ pq_discardbytes(size_t len)
{
while (PqRecvPointer >= PqRecvLength)
{
- if (pq_recvbuf()) /* If nothing in buffer, then recv some */
+ if (pq_recvbuf(false) == EOF) /* If nothing in buffer, then recv some */
return EOF; /* Failed to recv data */
}
amount = PqRecvLength - PqRecvPointer;
@@ -1176,7 +1194,7 @@ pq_getstring(StringInfo s)
{
while (PqRecvPointer >= PqRecvLength)
{
- if (pq_recvbuf()) /* If nothing in buffer, then recv some */
+ if (pq_recvbuf(false) == EOF) /* If nothing in buffer, then recv some */
return EOF; /* Failed to recv data */
}
@@ -1426,13 +1444,18 @@ internal_flush(void)
char *bufptr = PqSendBuffer + PqSendStart;
char *bufend = PqSendBuffer + PqSendPointer;
- while (bufptr < bufend)
+ while (bufptr < bufend || zpq_buffered(PqStream) != 0) /* has more data to flush or unsent data in internal compression buffer */
{
- int r;
-
- r = secure_write(MyProcPort, bufptr, bufend - bufptr);
-
- if (r <= 0)
+ int r;
+ size_t processed = 0;
+ size_t available = bufend - bufptr;
+ r = PqStream
+ ? zpq_write(PqStream, bufptr, available, &processed)
+ : secure_write(MyProcPort, bufptr, available);
+ bufptr += processed;
+ PqSendStart += processed;
+
+ if (r < 0 || (r == 0 && available))
{
if (errno == EINTR)
continue; /* Ok if we were interrupted */
@@ -1480,7 +1503,6 @@ internal_flush(void)
bufptr += r;
PqSendStart += r;
}
-
PqSendStart = PqSendPointer = 0;
return 0;
}
diff --git a/src/backend/postmaster/postmaster.c b/src/backend/postmaster/postmaster.c
index a4b53b3..3928e89 100644
--- a/src/backend/postmaster/postmaster.c
+++ b/src/backend/postmaster/postmaster.c
@@ -2053,6 +2053,16 @@ retry1:
port->database_name = pstrdup(valptr);
else if (strcmp(nameptr, "user") == 0)
port->user_name = pstrdup(valptr);
+ else if (strcmp(nameptr, "compression") == 0)
+ {
+ if (!parse_bool(valptr, &port->use_compression))
+ ereport(FATAL,
+ (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+ errmsg("invalid boolean value for parameter \"%s\": \"%s\"",
+ "compression",
+ valptr),
+ errhint("Valid values are: \"false\", \"off\", 0, \"true\", \"on\", 1.")));
+ }
else if (strcmp(nameptr, "options") == 0)
port->cmdline_options = pstrdup(valptr);
else if (strcmp(nameptr, "replication") == 0)
@@ -4257,6 +4267,14 @@ BackendInitialize(Port *port)
if (status != STATUS_OK)
proc_exit(0);
+ if (pq_configure(port))
+ {
+ ereport(COMMERROR,
+ (errcode_for_socket_access(),
+ errmsg("failed to send compression message: %m")));
+ proc_exit(0);
+ }
+
/*
* Now that we have the user and database name, we can set the process
* title for ps. It's good to do this as early as possible in startup.
diff --git a/src/bin/pgbench/pgbench.c b/src/bin/pgbench/pgbench.c
index f0c5149..efc4ac5 100644
--- a/src/bin/pgbench/pgbench.c
+++ b/src/bin/pgbench/pgbench.c
@@ -188,6 +188,7 @@ int nclients = 1; /* number of clients */
int nthreads = 1; /* number of threads */
bool is_connect; /* establish connection for each transaction */
bool is_latencies; /* report per-command latencies */
+bool libpq_compression; /* use libpq compression */
int main_pid; /* main process id used in log filename */
char *pghost = "";
@@ -590,6 +591,7 @@ usage(void)
" -h, --host=HOSTNAME database server host or socket directory\n"
" -p, --port=PORT database server port number\n"
" -U, --username=USERNAME connect as specified database user\n"
+ " -Z, --compression use libpq compression\n"
" -V, --version output version information, then exit\n"
" -?, --help show this help, then exit\n"
"\n"
@@ -1107,7 +1109,7 @@ doConnect(void)
*/
do
{
-#define PARAMS_ARRAY_SIZE 7
+#define PARAMS_ARRAY_SIZE 8
const char *keywords[PARAMS_ARRAY_SIZE];
const char *values[PARAMS_ARRAY_SIZE];
@@ -1124,8 +1126,10 @@ doConnect(void)
values[4] = dbName;
keywords[5] = "fallback_application_name";
values[5] = progname;
- keywords[6] = NULL;
- values[6] = NULL;
+ keywords[6] = "compression";
+ values[6] = libpq_compression ? "on" : "off";
+ keywords[7] = NULL;
+ values[7] = NULL;
new_pass = false;
@@ -4759,6 +4763,7 @@ main(int argc, char **argv)
{"builtin", required_argument, NULL, 'b'},
{"client", required_argument, NULL, 'c'},
{"connect", no_argument, NULL, 'C'},
+ {"compression", no_argument, NULL, 'Z'},
{"debug", no_argument, NULL, 'd'},
{"define", required_argument, NULL, 'D'},
{"file", required_argument, NULL, 'f'},
@@ -4868,12 +4873,15 @@ main(int argc, char **argv)
exit(1);
}
- while ((c = getopt_long(argc, argv, "iI:h:nvp:dqb:SNc:j:Crs:t:T:U:lf:D:F:M:P:R:L:", long_options, &optindex)) != -1)
+ while ((c = getopt_long(argc, argv, "iI:h:nvp:dqb:SNc:j:Crs:t:T:U:lf:D:F:M:P:R:L:Z", long_options, &optindex)) != -1)
{
char *script;
switch (c)
{
+ case 'Z':
+ libpq_compression = true;
+ break;
case 'i':
is_init_mode = true;
break;
diff --git a/src/bin/psql/help.c b/src/bin/psql/help.c
index 702e742..ae7a14c 100644
--- a/src/bin/psql/help.c
+++ b/src/bin/psql/help.c
@@ -139,6 +139,7 @@ usage(unsigned short int pager)
fprintf(output, _(" -U, --username=USERNAME database user name (default: \"%s\")\n"), env);
fprintf(output, _(" -w, --no-password never prompt for password\n"));
fprintf(output, _(" -W, --password force password prompt (should happen automatically)\n"));
+ fprintf(output, _(" -Z, --compression compress traffic with server\n"));
fprintf(output, _("\nFor more information, type \"\\?\" (for internal commands) or \"\\help\" (for SQL\n"
"commands) from within psql, or consult the psql section in the PostgreSQL\n"
diff --git a/src/bin/psql/startup.c b/src/bin/psql/startup.c
index be57574..9271716 100644
--- a/src/bin/psql/startup.c
+++ b/src/bin/psql/startup.c
@@ -75,6 +75,7 @@ struct adhoc_opts
bool no_psqlrc;
bool single_txn;
bool list_dbs;
+ bool compression;
SimpleActionList actions;
};
@@ -237,8 +238,10 @@ main(int argc, char *argv[])
values[5] = pset.progname;
keywords[6] = "client_encoding";
values[6] = (pset.notty || getenv("PGCLIENTENCODING")) ? NULL : "auto";
- keywords[7] = NULL;
- values[7] = NULL;
+ keywords[7] = "compression";
+ values[7] = options.compression ? "on" : "off";
+ keywords[8] = NULL;
+ values[8] = NULL;
new_pass = false;
pset.db = PQconnectdbParams(keywords, values, true);
@@ -436,6 +439,7 @@ parse_psql_options(int argc, char *argv[], struct adhoc_opts *options)
{"echo-all", no_argument, NULL, 'a'},
{"no-align", no_argument, NULL, 'A'},
{"command", required_argument, NULL, 'c'},
+ {"compression", no_argument, NULL, 'Z'},
{"dbname", required_argument, NULL, 'd'},
{"echo-queries", no_argument, NULL, 'e'},
{"echo-errors", no_argument, NULL, 'b'},
@@ -476,7 +480,7 @@ parse_psql_options(int argc, char *argv[], struct adhoc_opts *options)
memset(options, 0, sizeof *options);
- while ((c = getopt_long(argc, argv, "aAbc:d:eEf:F:h:HlL:no:p:P:qR:sStT:U:v:VwWxXz?01",
+ while ((c = getopt_long(argc, argv, "aAbc:d:eEf:F:h:HlL:no:p:P:qR:sStT:U:v:VwWxXz?01Z",
long_options, &optindex)) != -1)
{
switch (c)
@@ -540,6 +544,9 @@ parse_psql_options(int argc, char *argv[], struct adhoc_opts *options)
case 'p':
options->port = pg_strdup(optarg);
break;
+ case 'Z':
+ options->compression = true;
+ break;
case 'P':
{
char *value;
diff --git a/src/bin/scripts/pg_isready.c b/src/bin/scripts/pg_isready.c
index f7ad7b4..5d035cd 100644
--- a/src/bin/scripts/pg_isready.c
+++ b/src/bin/scripts/pg_isready.c
@@ -34,7 +34,7 @@ main(int argc, char **argv)
const char *pghostaddr_str = NULL;
const char *pgport_str = NULL;
-#define PARAMS_ARRAY_SIZE 7
+#define PARAMS_ARRAY_SIZE 8
const char *keywords[PARAMS_ARRAY_SIZE];
const char *values[PARAMS_ARRAY_SIZE];
diff --git a/src/common/Makefile b/src/common/Makefile
index 1fc2c66..f804fe1 100644
--- a/src/common/Makefile
+++ b/src/common/Makefile
@@ -43,7 +43,7 @@ LIBS += $(PTHREAD_LIBS)
OBJS_COMMON = base64.o config_info.o controldata_utils.o exec.o file_perm.o \
ip.o keywords.o md5.o pg_lzcompress.o pgfnames.o psprintf.o relpath.o \
rmtree.o saslprep.o scram-common.o string.o unicode_norm.o \
- username.o wait_error.o
+ username.o wait_error.o zpq_stream.o
ifeq ($(with_openssl),yes)
OBJS_COMMON += sha2_openssl.o
diff --git a/src/common/zpq_stream.c b/src/common/zpq_stream.c
new file mode 100644
index 0000000..dbb05f2
--- /dev/null
+++ b/src/common/zpq_stream.c
@@ -0,0 +1,368 @@
+#include "postgres_fe.h"
+#include "common/zpq_stream.h"
+#include "c.h"
+#include "pg_config.h"
+
+#if HAVE_LIBZSTD
+
+#include <malloc.h>
+#include <zstd.h>
+
+#define ZPQ_BUFFER_SIZE (8*1024)
+#define ZSTD_COMPRESSION_LEVEL 1
+
+struct ZpqStream
+{
+ ZSTD_CStream* tx_stream;
+ ZSTD_DStream* rx_stream;
+ ZSTD_outBuffer tx;
+ ZSTD_inBuffer rx;
+ size_t tx_not_flushed; /* Amount of datas in internal zstd buffer */
+ size_t tx_buffered; /* Data which is consumed by zpq_read but not yet sent */
+ zpq_tx_func tx_func;
+ zpq_rx_func rx_func;
+ void* arg;
+ char const* rx_error; /* Decompress error message */
+ size_t tx_total;
+ size_t tx_total_raw;
+ size_t rx_total;
+ size_t rx_total_raw;
+ char tx_buf[ZPQ_BUFFER_SIZE];
+ char rx_buf[ZPQ_BUFFER_SIZE];
+};
+
+ZpqStream*
+zpq_create(zpq_tx_func tx_func, zpq_rx_func rx_func, void *arg)
+{
+ ZpqStream* zs = (ZpqStream*)malloc(sizeof(ZpqStream));
+ zs->tx_stream = ZSTD_createCStream();
+ ZSTD_initCStream(zs->tx_stream, ZSTD_COMPRESSION_LEVEL);
+ zs->rx_stream = ZSTD_createDStream();
+ ZSTD_initDStream(zs->rx_stream);
+ zs->tx.dst = zs->tx_buf;
+ zs->tx.pos = 0;
+ zs->tx.size = ZPQ_BUFFER_SIZE;
+ zs->rx.src = zs->rx_buf;
+ zs->rx.pos = 0;
+ zs->rx.size = 0;
+ zs->rx_func = rx_func;
+ zs->tx_func = tx_func;
+ zs->tx_buffered = 0;
+ zs->tx_not_flushed = 0;
+ zs->rx_error = NULL;
+ zs->arg = arg;
+ zs->tx_total = zs->tx_total_raw = 0;
+ zs->rx_total = zs->rx_total_raw = 0;
+ return zs;
+}
+
+ssize_t
+zpq_read(ZpqStream *zs, void *buf, size_t size, size_t *processed)
+{
+ ssize_t rc;
+ ZSTD_outBuffer out;
+ out.dst = buf;
+ out.pos = 0;
+ out.size = size;
+
+ while (1)
+ {
+ rc = ZSTD_decompressStream(zs->rx_stream, &out, &zs->rx);
+ if (ZSTD_isError(rc))
+ {
+ zs->rx_error = ZSTD_getErrorName(rc);
+ return ZPQ_DECOMPRESS_ERROR;
+ }
+ /* Return result if we fill requested amount of bytes or read operation was performed */
+ if (out.pos != 0)
+ {
+ zs->rx_total_raw += out.pos;
+ return out.pos;
+ }
+ if (zs->rx.pos == zs->rx.size)
+ {
+ zs->rx.pos = zs->rx.size = 0; /* Reset rx buffer */
+ }
+ rc = zs->rx_func(zs->arg, (char*)zs->rx.src + zs->rx.size, ZPQ_BUFFER_SIZE - zs->rx.size);
+ if (rc > 0) /* read fetches some data */
+ {
+ zs->rx.size += rc;
+ zs->rx_total += rc;
+ }
+ else /* read failed */
+ {
+ *processed = out.pos;
+ zs->rx_total_raw += out.pos;
+ return rc;
+ }
+ }
+}
+
+ssize_t
+zpq_write(ZpqStream *zs, void const *buf, size_t size, size_t *processed)
+{
+ ssize_t rc;
+ ZSTD_inBuffer in_buf;
+ in_buf.src = buf;
+ in_buf.pos = 0;
+ in_buf.size = size;
+
+ do
+ {
+ if (zs->tx.pos == 0) /* Compress buffer is empty */
+ {
+ zs->tx.dst = zs->tx_buf; /* Reset pointer to the beginning of buffer */
+
+ if (in_buf.pos < size) /* Has something to compress in input buffer */
+ ZSTD_compressStream(zs->tx_stream, &zs->tx, &in_buf);
+
+ if (in_buf.pos == size) /* All data is compressed: flushed internal zstd buffer */
+ {
+ zs->tx_not_flushed = ZSTD_flushStream(zs->tx_stream, &zs->tx);
+ }
+ }
+ rc = zs->tx_func(zs->arg, zs->tx.dst, zs->tx.pos);
+ if (rc > 0)
+ {
+ zs->tx.pos -= rc;
+ zs->tx.dst = (char*)zs->tx.dst + rc;
+ zs->tx_total += rc;
+ }
+ else
+ {
+ *processed = in_buf.pos;
+ zs->tx_buffered = zs->tx.pos;
+ zs->tx_total_raw += in_buf.pos;
+ return rc;
+ }
+ } while (zs->tx.pos == 0 && (in_buf.pos < size || zs->tx_not_flushed)); /* repeat sending data until first partial write */
+
+ zs->tx_total_raw += in_buf.pos;
+ zs->tx_buffered = zs->tx.pos;
+ return in_buf.pos;
+}
+
+void
+zpq_free(ZpqStream *zs)
+{
+ if (zs != NULL)
+ {
+ ZSTD_freeCStream(zs->tx_stream);
+ ZSTD_freeDStream(zs->rx_stream);
+ free(zs);
+ }
+}
+
+char const*
+zpq_error(ZpqStream *zs)
+{
+ return zs->rx_error;
+}
+
+size_t
+zpq_buffered(ZpqStream *zs)
+{
+ return zs != NULL ? zs->tx_buffered + zs->tx_not_flushed : 0;
+}
+
+#elif HAVE_LIBZ
+
+#include <malloc.h>
+#include <zlib.h>
+
+#define ZPQ_BUFFER_SIZE 8192
+#define ZLIB_COMPRESSION_LEVEL 1
+
+struct ZpqStream
+{
+ z_stream tx;
+ z_stream rx;
+
+ zpq_tx_func tx_func;
+ zpq_rx_func rx_func;
+ void* arg;
+
+ size_t tx_buffered;
+
+ Bytef tx_buf[ZPQ_BUFFER_SIZE];
+ Bytef rx_buf[ZPQ_BUFFER_SIZE];
+};
+
+ZpqStream*
+zpq_create(zpq_tx_func tx_func, zpq_rx_func rx_func, void *arg)
+{
+ int rc;
+ ZpqStream* zs = (ZpqStream*)malloc(sizeof(ZpqStream));
+ memset(&zs->tx, 0, sizeof(zs->tx));
+ zs->tx.next_out = zs->tx_buf;
+ zs->tx.avail_out = ZPQ_BUFFER_SIZE;
+ zs->tx_buffered = 0;
+ rc = deflateInit(&zs->tx, ZLIB_COMPRESSION_LEVEL);
+ if (rc != Z_OK)
+ {
+ free(zs);
+ return NULL;
+ }
+ Assert(zs->tx.next_out == zs->tx_buf && zs->tx.avail_out == ZPQ_BUFFER_SIZE);
+
+ memset(&zs->rx, 0, sizeof(zs->tx));
+ zs->rx.next_in = zs->rx_buf;
+ zs->rx.avail_in = ZPQ_BUFFER_SIZE;
+ rc = inflateInit(&zs->rx);
+ if (rc != Z_OK)
+ {
+ free(zs);
+ return NULL;
+ }
+ Assert(zs->rx.next_in == zs->rx_buf && zs->rx.avail_in == ZPQ_BUFFER_SIZE);
+ zs->rx.avail_in = 0;
+
+ zs->rx_func = rx_func;
+ zs->tx_func = tx_func;
+ zs->arg = arg;
+
+ return zs;
+}
+
+ssize_t
+zpq_read(ZpqStream *zs, void *buf, size_t size, size_t *processed)
+{
+ int rc;
+ zs->rx.next_out = (Bytef *)buf;
+ zs->rx.avail_out = size;
+
+ while (1)
+ {
+ if (zs->rx.avail_in != 0) /* If there is some data in receiver buffer, then decompress it */
+ {
+ rc = inflate(&zs->rx, Z_SYNC_FLUSH);
+ if (rc != Z_OK)
+ {
+ return ZPQ_DECOMPRESS_ERROR;
+ }
+ if (zs->rx.avail_out != size)
+ {
+ return size - zs->rx.avail_out;
+ }
+ if (zs->rx.avail_in == 0)
+ {
+ zs->rx.next_in = zs->rx_buf;
+ }
+ }
+ else
+ {
+ zs->rx.next_in = zs->rx_buf;
+ }
+ rc = zs->rx_func(zs->arg, zs->rx.next_in + zs->rx.avail_in, zs->rx_buf + ZPQ_BUFFER_SIZE - zs->rx.next_in - zs->rx.avail_in);
+ if (rc > 0)
+ {
+ zs->rx.avail_in += rc;
+ }
+ else
+ {
+ *processed = size - zs->rx.avail_out;
+ return rc;
+ }
+ }
+}
+
+ssize_t
+zpq_write(ZpqStream *zs, void const *buf, size_t size, size_t *processed)
+{
+ int rc;
+ zs->tx.next_in = (Bytef *)buf;
+ zs->tx.avail_in = size;
+ do
+ {
+ if (zs->tx.avail_out == ZPQ_BUFFER_SIZE) /* Compress buffer is empty */
+ {
+ zs->tx.next_out = zs->tx_buf; /* Reset pointer to the beginning of buffer */
+
+ if (zs->tx.avail_in != 0) /* Has something in input buffer */
+ {
+ rc = deflate(&zs->tx, Z_SYNC_FLUSH);
+ Assert(rc == Z_OK);
+ zs->tx.next_out = zs->tx_buf; /* Reset pointer to the beginning of buffer */
+ }
+ }
+ rc = zs->tx_func(zs->arg, zs->tx.next_out, ZPQ_BUFFER_SIZE - zs->tx.avail_out);
+ if (rc > 0)
+ {
+ zs->tx.next_out += rc;
+ zs->tx.avail_out += rc;
+ }
+ else
+ {
+ *processed = size - zs->tx.avail_in;
+ zs->tx_buffered = ZPQ_BUFFER_SIZE - zs->tx.avail_out;
+ return rc;
+ }
+ } while (zs->tx.avail_out == ZPQ_BUFFER_SIZE && zs->tx.avail_in != 0); /* repeat sending data until first partial write */
+
+ zs->tx_buffered = ZPQ_BUFFER_SIZE - zs->tx.avail_out;
+
+ return size - zs->tx.avail_in;
+}
+
+void
+zpq_free(ZpqStream *zs)
+{
+ if (zs != NULL)
+ {
+ inflateEnd(&zs->rx);
+ deflateEnd(&zs->tx);
+ free(zs);
+ }
+}
+
+char const*
+zpq_error(ZpqStream *zs)
+{
+ return zs->rx.msg;
+}
+
+size_t
+zpq_buffered(ZpqStream *zs)
+{
+ return zs != NULL ? zs->tx_buffered : 0;
+}
+
+#else
+
+ZpqStream*
+zpq_create(zpq_tx_func tx_func, zpq_rx_func rx_func, void *arg)
+{
+ return NULL;
+}
+
+ssize_t
+zpq_read(ZpqStream *zs, void *buf, size_t size)
+{
+ return -1;
+}
+
+ssize_t
+zpq_write(ZpqStream *zs, void const *buf, size_t size)
+{
+ return -1;
+}
+
+void
+zpq_free(ZpqStream *zs)
+{
+}
+
+char const*
+zpq_error(ZpqStream *zs)
+{
+ return NULL;
+}
+
+
+size_t
+zpq_buffered(ZpqStream *zs)
+{
+ return 0;
+}
+
+#endif
diff --git a/src/include/common/zpq_stream.h b/src/include/common/zpq_stream.h
new file mode 100644
index 0000000..dc765af
--- /dev/null
+++ b/src/include/common/zpq_stream.h
@@ -0,0 +1,28 @@
+/*
+ * zpq_stream.h
+ * Streaiming compression for libpq
+ */
+
+#ifndef ZPQ_STREAM_H
+#define ZPQ_STREAM_H
+
+#include <stdlib.h>
+
+#define ZPQ_IO_ERROR (-1)
+#define ZPQ_DECOMPRESS_ERROR (-2)
+
+struct ZpqStream;
+typedef struct ZpqStream ZpqStream;
+
+typedef ssize_t(*zpq_tx_func)(void* arg, void const* data, size_t size);
+typedef ssize_t(*zpq_rx_func)(void* arg, void* data, size_t size);
+
+
+ZpqStream* zpq_create(zpq_tx_func tx_func, zpq_rx_func rx_func, void* arg);
+ssize_t zpq_read(ZpqStream* zs, void* buf, size_t size, size_t* processed);
+ssize_t zpq_write(ZpqStream* zs, void const* buf, size_t size, size_t* processed);
+char const* zpq_error(ZpqStream* zs);
+size_t zpq_buffered(ZpqStream* zs);
+void zpq_free(ZpqStream* zs);
+
+#endif
diff --git a/src/include/libpq/libpq-be.h b/src/include/libpq/libpq-be.h
index 7698cd1..5203f2d 100644
--- a/src/include/libpq/libpq-be.h
+++ b/src/include/libpq/libpq-be.h
@@ -182,6 +182,8 @@ typedef struct Port
char *peer_cn;
bool peer_cert_valid;
+ bool use_compression;
+
/*
* OpenSSL structures. (Keep these last so that the locations of other
* fields are the same whether or not you build with OpenSSL.)
diff --git a/src/include/libpq/libpq.h b/src/include/libpq/libpq.h
index 7bf06c6..cb0b69e 100644
--- a/src/include/libpq/libpq.h
+++ b/src/include/libpq/libpq.h
@@ -61,6 +61,7 @@ extern void StreamClose(pgsocket sock);
extern void TouchSocketFiles(void);
extern void RemoveSocketFiles(void);
extern void pq_init(void);
+extern int pq_configure(Port* port);
extern int pq_getbytes(char *s, size_t len);
extern int pq_getstring(StringInfo s);
extern void pq_startmsgread(void);
diff --git a/src/include/pg_config.h.in b/src/include/pg_config.h.in
index 9411f48..c0ea383 100644
--- a/src/include/pg_config.h.in
+++ b/src/include/pg_config.h.in
@@ -365,6 +365,9 @@
/* Define to 1 if you have the `z' library (-lz). */
#undef HAVE_LIBZ
+/* Define to 1 if you have the `zstd' library (-lzstd). */
+#undef HAVE_LIBZSTD
+
/* Define to 1 if the system has the type `locale_t'. */
#undef HAVE_LOCALE_T
diff --git a/src/interfaces/libpq/Makefile b/src/interfaces/libpq/Makefile
index abe0a50..2dad4fb 100644
--- a/src/interfaces/libpq/Makefile
+++ b/src/interfaces/libpq/Makefile
@@ -29,6 +29,16 @@ endif
# platforms require special flags.
LIBS := $(LIBS:-lpgport=)
+ifeq ($(with_zstd),yes)
+LIBS += -lzstd
+SHLIB_LINK += -lzstd
+endif
+
+ifeq ($(with_zlib),yes)
+LIBS += -lz
+SHLIB_LINK += -lz
+endif
+
# We can't use Makefile variables here because the MSVC build system scrapes
# OBJS from this file.
OBJS= fe-auth.o fe-auth-scram.o fe-connect.o fe-exec.o fe-misc.o fe-print.o fe-lobj.o \
@@ -49,7 +59,7 @@ endif
# src/backend/utils/mb
OBJS += encnames.o wchar.o
# src/common
-OBJS += base64.o ip.o md5.o scram-common.o saslprep.o unicode_norm.o
+OBJS += base64.o ip.o md5.o scram-common.o saslprep.o unicode_norm.o zpq_stream.o
ifeq ($(with_openssl),yes)
OBJS += fe-secure-openssl.o fe-secure-common.o sha2_openssl.o
@@ -106,7 +116,7 @@ backend_src = $(top_srcdir)/src/backend
chklocale.c crypt.c erand48.c getaddrinfo.c getpeereid.c inet_aton.c inet_net_ntop.c noblock.c open.c system.c pgsleep.c pg_strong_random.c pgstrcasecmp.c pqsignal.c snprintf.c strerror.c strlcpy.c strnlen.c thread.c win32error.c win32setlocale.c: % : $(top_srcdir)/src/port/%
rm -f $@ && $(LN_S) $< .
-ip.c md5.c base64.c scram-common.c sha2.c sha2_openssl.c saslprep.c unicode_norm.c: % : $(top_srcdir)/src/common/%
+ip.c md5.c base64.c scram-common.c sha2.c sha2_openssl.c saslprep.c unicode_norm.c zpq_stream.c: % : $(top_srcdir)/src/common/%
rm -f $@ && $(LN_S) $< .
encnames.c wchar.c: % : $(backend_src)/utils/mb/%
@@ -156,7 +166,7 @@ clean distclean: clean-lib
rm -f pg_config_paths.h
# Remove files we (may have) symlinked in from src/port and other places
rm -f chklocale.c crypt.c erand48.c getaddrinfo.c getpeereid.c inet_aton.c inet_net_ntop.c noblock.c open.c system.c pgsleep.c pg_strong_random.c pgstrcasecmp.c pqsignal.c snprintf.c strerror.c strlcpy.c strnlen.c thread.c win32error.c win32setlocale.c
- rm -f ip.c md5.c base64.c scram-common.c sha2.c sha2_openssl.c saslprep.c unicode_norm.c
+ rm -f ip.c md5.c base64.c scram-common.c sha2.c sha2_openssl.c saslprep.c unicode_norm.c zpq_stream.c
rm -f encnames.c wchar.c
maintainer-clean: distclean maintainer-clean-lib
diff --git a/src/interfaces/libpq/fe-connect.c b/src/interfaces/libpq/fe-connect.c
index a7e969d..6fabc5b 100644
--- a/src/interfaces/libpq/fe-connect.c
+++ b/src/interfaces/libpq/fe-connect.c
@@ -72,6 +72,7 @@ static int ldapServiceLookup(const char *purl, PQconninfoOption *options,
#include "common/ip.h"
#include "common/scram-common.h"
+#include "common/zpq_stream.h"
#include "mb/pg_wchar.h"
#include "port/pg_bswap.h"
@@ -269,6 +270,10 @@ static const internalPQconninfoOption PQconninfoOptions[] = {
21, /* sizeof("tls-server-end-point") == 21 */
offsetof(struct pg_conn, scram_channel_binding)},
+ {"compression", "COMPRESSION", "0", NULL,
+ "ZSTD-Compression", "", 1,
+ offsetof(struct pg_conn, compression)},
+
/*
* ssl options are allowed even without client SSL support because the
* client can still handle SSL modes "disable" and "allow". Other
@@ -325,6 +330,10 @@ static const internalPQconninfoOption PQconninfoOptions[] = {
"Replication", "D", 5,
offsetof(struct pg_conn, replication)},
+ {"compression", NULL, NULL, NULL,
+ "Compression", "Z", 5,
+ offsetof(struct pg_conn, compression)},
+
{"target_session_attrs", "PGTARGETSESSIONATTRS",
DefaultTargetSessionAttrs, NULL,
"Target-Session-Attrs", "", 11, /* sizeof("read-write") = 11 */
@@ -430,6 +439,10 @@ pgthreadlock_t pg_g_threadlock = default_threadlock;
void
pqDropConnection(PGconn *conn, bool flushInput)
{
+ /* Release compression streams */
+ zpq_free(conn->zstream);
+ conn->zstream = NULL;
+
/* Drop any SSL state */
pqsecure_close(conn);
@@ -2648,11 +2661,23 @@ keep_going: /* We will come back to here until there is
*/
conn->inCursor = conn->inStart;
- /* Read type byte */
- if (pqGetc(&beresp, conn))
+ while (1)
{
- /* We'll come back when there is more data */
- return PGRES_POLLING_READING;
+ /* Read type byte */
+ if (pqGetc(&beresp, conn))
+ {
+ /* We'll come back when there is more data */
+ return PGRES_POLLING_READING;
+ }
+
+ if (beresp == 'z') /* Switch on compression */
+ {
+ /* mark byte consumed */
+ conn->inStart = conn->inCursor;
+ Assert(!conn->zstream);
+ conn->zstream = zpq_create((zpq_tx_func)pqsecure_write, (zpq_rx_func)pqsecure_read, conn);
+ } else
+ break;
}
/*
@@ -3462,6 +3487,8 @@ freePGconn(PGconn *conn)
free(conn->dbName);
if (conn->replication)
free(conn->replication);
+ if (conn->compression)
+ free(conn->compression);
if (conn->pguser)
free(conn->pguser);
if (conn->pgpass)
diff --git a/src/interfaces/libpq/fe-misc.c b/src/interfaces/libpq/fe-misc.c
index 2a6637f..488f8d2 100644
--- a/src/interfaces/libpq/fe-misc.c
+++ b/src/interfaces/libpq/fe-misc.c
@@ -53,11 +53,12 @@
#include "port/pg_bswap.h"
#include "pg_config_paths.h"
+#include <common/zpq_stream.h>
static int pqPutMsgBytes(const void *buf, size_t len, PGconn *conn);
static int pqSendSome(PGconn *conn, int len);
-static int pqSocketCheck(PGconn *conn, int forRead, int forWrite,
- time_t end_time);
+static int pqSocketCheck(PGconn *conn, int forRead, int forWrite,
+ time_t end_time);
static int pqSocketPoll(int sock, int forRead, int forWrite, time_t end_time);
/*
@@ -630,6 +631,7 @@ pqReadData(PGconn *conn)
{
int someread = 0;
int nread;
+ size_t processed;
if (conn->sock == PGINVALID_SOCKET)
{
@@ -678,10 +680,23 @@ pqReadData(PGconn *conn)
/* OK, try to read some data */
retry3:
- nread = pqsecure_read(conn, conn->inBuffer + conn->inEnd,
- conn->inBufSize - conn->inEnd);
+ processed = 0;
+ nread = conn->zstream
+ ? zpq_read(conn->zstream, conn->inBuffer + conn->inEnd,
+ conn->inBufSize - conn->inEnd, &processed)
+ : pqsecure_read(conn, conn->inBuffer + conn->inEnd,
+ conn->inBufSize - conn->inEnd);
+ conn->inEnd += processed;
if (nread < 0)
{
+ if (nread == ZPQ_DECOMPRESS_ERROR)
+ {
+ printfPQExpBuffer(&conn->errorMessage,
+ libpq_gettext("decompress error: %s\n"),
+ zpq_error(conn->zstream));
+ return -1;
+ }
+
if (SOCK_ERRNO == EINTR)
goto retry3;
/* Some systems return EAGAIN/EWOULDBLOCK for no data */
@@ -768,10 +783,24 @@ retry3:
* arrived.
*/
retry4:
- nread = pqsecure_read(conn, conn->inBuffer + conn->inEnd,
- conn->inBufSize - conn->inEnd);
+ processed = 0;
+ nread = conn->zstream
+ ? zpq_read(conn->zstream, conn->inBuffer + conn->inEnd,
+ conn->inBufSize - conn->inEnd, &processed)
+ : pqsecure_read(conn, conn->inBuffer + conn->inEnd,
+ conn->inBufSize - conn->inEnd);
+ conn->inEnd += processed;
+
if (nread < 0)
{
+ if (nread == ZPQ_DECOMPRESS_ERROR)
+ {
+ printfPQExpBuffer(&conn->errorMessage,
+ libpq_gettext("decompress error: %s\n"),
+ zpq_error(conn->zstream));
+ return -1;
+ }
+
if (SOCK_ERRNO == EINTR)
goto retry4;
/* Some systems return EAGAIN/EWOULDBLOCK for no data */
@@ -842,12 +871,14 @@ pqSendSome(PGconn *conn, int len)
}
/* while there's still data to send */
- while (len > 0)
+ while (len > 0 || zpq_buffered(conn->zstream))
{
int sent;
-
+ size_t processed = 0;
+ sent = conn->zstream
+ ? zpq_write(conn->zstream, ptr, len, &processed)
#ifndef WIN32
- sent = pqsecure_write(conn, ptr, len);
+ : pqsecure_write(conn, ptr, len);
#else
/*
@@ -855,8 +886,11 @@ pqSendSome(PGconn *conn, int len)
* failure-point appears to be different in different versions of
* Windows, but 64k should always be safe.
*/
- sent = pqsecure_write(conn, ptr, Min(len, 65536));
+ : pqsecure_write(conn, ptr, Min(len, 65536));
#endif
+ ptr += processed;
+ len -= processed;
+ remaining -= processed;
if (sent < 0)
{
@@ -896,7 +930,7 @@ pqSendSome(PGconn *conn, int len)
remaining -= sent;
}
- if (len > 0)
+ if (len > 0 || sent < 0 || zpq_buffered(conn->zstream))
{
/*
* We didn't send it all, wait till we can send more.
diff --git a/src/interfaces/libpq/fe-protocol3.c b/src/interfaces/libpq/fe-protocol3.c
index 8345faf..3942be1 100644
--- a/src/interfaces/libpq/fe-protocol3.c
+++ b/src/interfaces/libpq/fe-protocol3.c
@@ -2179,6 +2179,8 @@ build_startup_packet(const PGconn *conn, char *packet,
ADD_STARTUP_OPTION("database", conn->dbName);
if (conn->replication && conn->replication[0])
ADD_STARTUP_OPTION("replication", conn->replication);
+ if (conn->compression && conn->compression[0])
+ ADD_STARTUP_OPTION("compression", conn->compression);
if (conn->pgoptions && conn->pgoptions[0])
ADD_STARTUP_OPTION("options", conn->pgoptions);
if (conn->send_appname)
diff --git a/src/interfaces/libpq/libpq-int.h b/src/interfaces/libpq/libpq-int.h
index 9a586ff..6344eb6 100644
--- a/src/interfaces/libpq/libpq-int.h
+++ b/src/interfaces/libpq/libpq-int.h
@@ -40,6 +40,7 @@
/* include stuff common to fe and be */
#include "getaddrinfo.h"
#include "libpq/pqcomm.h"
+#include "common/zpq_stream.h"
/* include stuff found in fe only */
#include "pqexpbuffer.h"
@@ -357,6 +358,7 @@ struct pg_conn
char *sslrootcert; /* root certificate filename */
char *sslcrl; /* certificate revocation list filename */
char *requirepeer; /* required peer credentials for local sockets */
+ char *compression; /* stream compression (0 or 1) */
#if defined(ENABLE_GSS) || defined(ENABLE_SSPI)
char *krbsrvname; /* Kerberos service name */
@@ -495,6 +497,9 @@ struct pg_conn
/* Buffer for receiving various parts of messages */
PQExpBufferData workBuffer; /* expansible string */
+
+ /* Compression stream */
+ ZpqStream* zstream;
};
/* PGcancel stores all data necessary to cancel a connection. A copy of this
