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|
/* $NetBSD: pgfs_db.c,v 1.3 2012/04/11 14:27:43 yamt Exp $ */
/*-
* Copyright (c)2010,2011 YAMAMOTO Takashi,
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
/*
* backend db operations
*/
#include <sys/cdefs.h>
#ifndef lint
__RCSID("$NetBSD: pgfs_db.c,v 1.3 2012/04/11 14:27:43 yamt Exp $");
#endif /* not lint */
#include <assert.h>
#include <err.h>
#include <errno.h>
#include <inttypes.h>
#include <puffs.h>
#include <stdbool.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <util.h>
#include <libpq-fe.h>
#include "pgfs_db.h"
#include "pgfs_waitq.h"
#include "pgfs_debug.h"
bool pgfs_dosync = false;
struct Xconn {
TAILQ_ENTRY(Xconn) list;
PGconn *conn;
struct puffs_cc *blocker;
struct puffs_cc *owner;
bool in_trans;
int id;
const char *label;
};
static void
dumperror(struct Xconn *xc, const PGresult *res)
{
static const struct {
const char *name;
int code;
} fields[] = {
#define F(x) { .name = #x, .code = x, }
F(PG_DIAG_SEVERITY),
F(PG_DIAG_SQLSTATE),
F(PG_DIAG_MESSAGE_PRIMARY),
F(PG_DIAG_MESSAGE_DETAIL),
F(PG_DIAG_MESSAGE_HINT),
F(PG_DIAG_STATEMENT_POSITION),
F(PG_DIAG_INTERNAL_POSITION),
F(PG_DIAG_INTERNAL_QUERY),
F(PG_DIAG_CONTEXT),
F(PG_DIAG_SOURCE_FILE),
F(PG_DIAG_SOURCE_LINE),
F(PG_DIAG_SOURCE_FUNCTION),
#undef F
};
unsigned int i;
if (!pgfs_dodprintf) {
return;
}
assert(PQresultStatus(res) == PGRES_NONFATAL_ERROR ||
PQresultStatus(res) == PGRES_FATAL_ERROR);
for (i = 0; i < __arraycount(fields); i++) {
const char *val = PQresultErrorField(res, fields[i].code);
if (val == NULL) {
continue;
}
fprintf(stderr, "%s: %s\n", fields[i].name, val);
}
}
TAILQ_HEAD(, Xconn) xclist = TAILQ_HEAD_INITIALIZER(xclist);
struct waitq xcwaitq = TAILQ_HEAD_INITIALIZER(xcwaitq);
static struct Xconn *
getxc(struct puffs_cc *cc)
{
struct Xconn *xc;
assert(cc != NULL);
retry:
TAILQ_FOREACH(xc, &xclist, list) {
if (xc->blocker == NULL) {
assert(xc->owner == NULL);
xc->owner = cc;
DPRINTF("xc %p acquire %p\n", xc, cc);
return xc;
} else {
assert(xc->owner == xc->blocker);
}
}
DPRINTF("no free conn %p\n", cc);
waiton(&xcwaitq, cc);
goto retry;
}
static void
relxc(struct Xconn *xc)
{
assert(xc->in_trans);
assert(xc->owner != NULL);
xc->in_trans = false;
xc->owner = NULL;
wakeup_one(&xcwaitq);
}
static void
pqwait(struct Xconn *xc)
{
PGconn *conn = xc->conn;
struct puffs_cc *cc = xc->owner;
if (PQflush(conn)) {
errx(EXIT_FAILURE, "PQflush: %s", PQerrorMessage(conn));
}
if (!PQisBusy(conn)) {
return;
}
assert(xc->blocker == NULL);
xc->blocker = cc;
DPRINTF("yielding %p\n", cc);
/* XXX is it safe to yield before entering mainloop? */
puffs_cc_yield(cc);
DPRINTF("yield returned %p\n", cc);
assert(xc->owner == cc);
assert(xc->blocker == cc);
xc->blocker = NULL;
}
static int
sqltoerrno(const char *sqlstate)
{
/*
* XXX hack; ERRCODE_INTERNAL_ERROR -> EAGAIN to handle
* "tuple concurrently updated" errors for lowrite/lo_truncate.
*
* XXX should map ERRCODE_OUT_OF_MEMORY to EAGAIN?
*/
static const struct {
char sqlstate[5];
int error;
} map[] = {
{ "00000", 0, }, /* ERRCODE_SUCCESSFUL_COMPLETION */
{ "02000", ENOENT, }, /* ERRCODE_NO_DATA */
{ "23505", EEXIST, }, /* ERRCODE_UNIQUE_VIOLATION */
{ "23514", EINVAL, }, /* ERRCODE_CHECK_VIOLATION */
{ "40001", EAGAIN, }, /* ERRCODE_T_R_SERIALIZATION_FAILURE */
{ "40P01", EAGAIN, }, /* ERRCODE_T_R_DEADLOCK_DETECTED */
{ "42704", ENOENT, }, /* ERRCODE_UNDEFINED_OBJECT */
{ "53100", ENOSPC, }, /* ERRCODE_DISK_FULL */
{ "53200", ENOMEM, }, /* ERRCODE_OUT_OF_MEMORY */
{ "XX000", EAGAIN, }, /* ERRCODE_INTERNAL_ERROR */
};
unsigned int i;
for (i = 0; i < __arraycount(map); i++) {
if (!memcmp(map[i].sqlstate, sqlstate, 5)) {
const int error = map[i].error;
if (error != 0) {
DPRINTF("sqlstate %5s mapped to error %d\n",
sqlstate, error);
}
if (error == EINVAL) {
/*
* sounds like a bug.
*/
abort();
}
return error;
}
}
DPRINTF("unknown sqlstate %5s mapped to EIO\n", sqlstate);
return EIO;
}
struct cmd {
char name[32]; /* name of prepared statement */
char *cmd; /* query string */
unsigned int nparams;
Oid *paramtypes;
uint32_t prepared_mask; /* for which connections this is prepared? */
unsigned int flags; /* CMD_ flags */
};
#define CMD_NOPREPARE 1 /* don't prepare this command */
struct cmd *
createcmd(const char *cmd, unsigned int flags, ...)
{
struct cmd *c;
va_list ap;
const char *cp;
unsigned int i;
static unsigned int cmdid;
c = emalloc(sizeof(*c));
c->cmd = estrdup(cmd);
c->nparams = 0;
va_start(ap, flags);
for (cp = cmd; *cp != 0; cp++) {
if (*cp == '$') { /* XXX */
c->nparams++;
}
}
c->paramtypes = emalloc(c->nparams * sizeof(*c->paramtypes));
for (i = 0; i < c->nparams; i++) {
Oid type = va_arg(ap, Oid);
assert(type == BYTEA ||
type == INT4OID || type == INT8OID || type == OIDOID ||
type == TEXTOID || type == TIMESTAMPTZOID);
c->paramtypes[i] = type;
}
va_end(ap);
snprintf(c->name, sizeof(c->name), "%u", cmdid++);
if ((flags & CMD_NOPREPARE) != 0) {
c->prepared_mask = ~0;
} else {
c->prepared_mask = 0;
}
c->flags = flags;
return c;
}
static void
freecmd(struct cmd *c)
{
free(c->paramtypes);
free(c->cmd);
free(c);
}
static int
fetch_noresult(struct Xconn *xc)
{
PGresult *res;
ExecStatusType status;
PGconn *conn = xc->conn;
int error;
pqwait(xc);
res = PQgetResult(conn);
if (res == NULL) {
return ENOENT;
}
status = PQresultStatus(res);
if (status == PGRES_COMMAND_OK) {
assert(PQnfields(res) == 0);
assert(PQntuples(res) == 0);
if (!strcmp(PQcmdTuples(res), "0")) {
error = ENOENT;
} else {
error = 0;
}
} else if (status == PGRES_FATAL_ERROR) {
error = sqltoerrno(PQresultErrorField(res, PG_DIAG_SQLSTATE));
assert(error != 0);
dumperror(xc, res);
} else {
errx(1, "%s not command_ok: %d: %s", __func__,
(int)status,
PQerrorMessage(conn));
}
PQclear(res);
res = PQgetResult(conn);
assert(res == NULL);
if (error != 0) {
DPRINTF("error %d\n", error);
}
return error;
}
static int
preparecmd(struct Xconn *xc, struct cmd *c)
{
PGconn *conn = xc->conn;
const uint32_t mask = 1 << xc->id;
int error;
int ret;
if ((c->prepared_mask & mask) != 0) {
return 0;
}
assert((c->flags & CMD_NOPREPARE) == 0);
DPRINTF("PREPARE: '%s'\n", c->cmd);
ret = PQsendPrepare(conn, c->name, c->cmd, c->nparams, c->paramtypes);
if (!ret) {
errx(EXIT_FAILURE, "PQsendPrepare: %s",
PQerrorMessage(conn));
}
error = fetch_noresult(xc);
if (error != 0) {
return error;
}
c->prepared_mask |= mask;
return 0;
}
/*
* vsendcmd:
*
* resultmode is just passed to PQsendQueryParams/PQsendQueryPrepared.
* 0 for text and 1 for binary.
*/
static int
vsendcmd(struct Xconn *xc, int resultmode, struct cmd *c, va_list ap)
{
PGconn *conn = xc->conn;
char **paramvalues;
int *paramlengths;
int *paramformats;
unsigned int i;
int error;
int ret;
assert(xc->owner != NULL);
assert(xc->blocker == NULL);
error = preparecmd(xc, c);
if (error != 0) {
return error;
}
paramvalues = emalloc(c->nparams * sizeof(*paramvalues));
paramlengths = NULL;
paramformats = NULL;
DPRINTF("CMD: '%s'\n", c->cmd);
for (i = 0; i < c->nparams; i++) {
Oid type = c->paramtypes[i];
char tmpstore[1024];
const char *buf = NULL;
intmax_t v = 0; /* XXXgcc */
int sz;
bool binary = false;
switch (type) {
case BYTEA:
buf = va_arg(ap, const void *);
sz = (int)va_arg(ap, size_t);
binary = true;
break;
case INT8OID:
case OIDOID:
case INT4OID:
switch (type) {
case INT8OID:
v = (intmax_t)va_arg(ap, int64_t);
break;
case OIDOID:
v = (intmax_t)va_arg(ap, Oid);
break;
case INT4OID:
v = (intmax_t)va_arg(ap, int32_t);
break;
default:
errx(EXIT_FAILURE, "unknown integer oid %u",
type);
}
buf = tmpstore;
sz = snprintf(tmpstore, sizeof(tmpstore),
"%jd", v);
assert(sz != -1);
assert((size_t)sz < sizeof(tmpstore));
sz += 1;
break;
case TEXTOID:
case TIMESTAMPTZOID:
buf = va_arg(ap, char *);
sz = strlen(buf) + 1;
break;
default:
errx(EXIT_FAILURE, "%s: unknown param type %u",
__func__, type);
}
if (binary) {
if (paramlengths == NULL) {
paramlengths =
emalloc(c->nparams * sizeof(*paramformats));
}
if (paramformats == NULL) {
paramformats = ecalloc(1,
c->nparams * sizeof(*paramformats));
}
paramformats[i] = 1;
paramlengths[i] = sz;
}
paramvalues[i] = emalloc(sz);
memcpy(paramvalues[i], buf, sz);
if (binary) {
DPRINTF("\t[%u]=<BINARY>\n", i);
} else {
DPRINTF("\t[%u]='%s'\n", i, paramvalues[i]);
}
}
if ((c->flags & CMD_NOPREPARE) != 0) {
ret = PQsendQueryParams(conn, c->cmd, c->nparams, c->paramtypes,
(const char * const *)paramvalues, paramlengths,
paramformats, resultmode);
} else {
ret = PQsendQueryPrepared(conn, c->name, c->nparams,
(const char * const *)paramvalues, paramlengths,
paramformats, resultmode);
}
for (i = 0; i < c->nparams; i++) {
free(paramvalues[i]);
}
free(paramvalues);
free(paramlengths);
free(paramformats);
if (!ret) {
errx(EXIT_FAILURE, "PQsendQueryPrepared: %s",
PQerrorMessage(conn));
}
return 0;
}
int
sendcmd(struct Xconn *xc, struct cmd *c, ...)
{
va_list ap;
int error;
va_start(ap, c);
error = vsendcmd(xc, 0, c, ap);
va_end(ap);
return error;
}
int
sendcmdx(struct Xconn *xc, int resultmode, struct cmd *c, ...)
{
va_list ap;
int error;
va_start(ap, c);
error = vsendcmd(xc, resultmode, c, ap);
va_end(ap);
return error;
}
/*
* simplecmd: a convenient routine to execute a command which returns
* no rows synchronously.
*/
int
simplecmd(struct Xconn *xc, struct cmd *c, ...)
{
va_list ap;
int error;
va_start(ap, c);
error = vsendcmd(xc, 0, c, ap);
va_end(ap);
if (error != 0) {
return error;
}
return fetch_noresult(xc);
}
void
fetchinit(struct fetchstatus *s, struct Xconn *xc)
{
s->xc = xc;
s->res = NULL;
s->cur = 0;
s->nrows = 0;
s->done = false;
}
static intmax_t
getint(const char *str)
{
intmax_t i;
char *ep;
errno = 0;
i = strtoimax(str, &ep, 10);
assert(errno == 0);
assert(str[0] != 0);
assert(*ep == 0);
return i;
}
static int
vfetchnext(struct fetchstatus *s, unsigned int n, const Oid *types, va_list ap)
{
PGconn *conn = s->xc->conn;
unsigned int i;
assert(conn != NULL);
if (s->res == NULL) {
ExecStatusType status;
int error;
pqwait(s->xc);
s->res = PQgetResult(conn);
if (s->res == NULL) {
s->done = true;
return ENOENT;
}
status = PQresultStatus(s->res);
if (status == PGRES_FATAL_ERROR) {
error = sqltoerrno(
PQresultErrorField(s->res, PG_DIAG_SQLSTATE));
assert(error != 0);
dumperror(s->xc, s->res);
return error;
}
if (status != PGRES_TUPLES_OK) {
errx(1, "not tuples_ok: %s",
PQerrorMessage(conn));
}
assert((unsigned int)PQnfields(s->res) == n);
s->nrows = PQntuples(s->res);
if (s->nrows == 0) {
DPRINTF("no rows\n");
return ENOENT;
}
assert(s->nrows >= 1);
s->cur = 0;
}
for (i = 0; i < n; i++) {
size_t size;
assert((types[i] != BYTEA) == (PQfformat(s->res, i) == 0));
DPRINTF("[%u] PQftype = %d, types = %d, value = '%s'\n",
i, PQftype(s->res, i), types[i],
PQgetisnull(s->res, s->cur, i) ? "<NULL>" :
PQfformat(s->res, i) == 0 ? PQgetvalue(s->res, s->cur, i) :
"<BINARY>");
assert(PQftype(s->res, i) == types[i]);
assert(!PQgetisnull(s->res, s->cur, i));
switch(types[i]) {
case INT8OID:
*va_arg(ap, int64_t *) =
getint(PQgetvalue(s->res, s->cur, i));
break;
case OIDOID:
*va_arg(ap, Oid *) =
getint(PQgetvalue(s->res, s->cur, i));
break;
case INT4OID:
*va_arg(ap, int32_t *) =
getint(PQgetvalue(s->res, s->cur, i));
break;
case TEXTOID:
*va_arg(ap, char **) =
estrdup(PQgetvalue(s->res, s->cur, i));
break;
case BYTEA:
size = PQgetlength(s->res, s->cur, i);
memcpy(va_arg(ap, void *),
PQgetvalue(s->res, s->cur, i), size);
*va_arg(ap, size_t *) = size;
break;
default:
errx(EXIT_FAILURE, "%s unknown type %u", __func__,
types[i]);
}
}
s->cur++;
if (s->cur == s->nrows) {
PQclear(s->res);
s->res = NULL;
}
return 0;
}
int
fetchnext(struct fetchstatus *s, unsigned int n, const Oid *types, ...)
{
va_list ap;
int error;
va_start(ap, types);
error = vfetchnext(s, n, types, ap);
va_end(ap);
return error;
}
void
fetchdone(struct fetchstatus *s)
{
if (s->res != NULL) {
PQclear(s->res);
s->res = NULL;
}
if (!s->done) {
PGresult *res;
unsigned int n;
n = 0;
while ((res = PQgetResult(s->xc->conn)) != NULL) {
PQclear(res);
n++;
}
if (n > 0) {
DPRINTF("%u rows dropped\n", n);
}
}
}
int
simplefetch(struct Xconn *xc, Oid type, ...)
{
struct fetchstatus s;
va_list ap;
int error;
fetchinit(&s, xc);
va_start(ap, type);
error = vfetchnext(&s, 1, &type, ap);
va_end(ap);
assert(error != 0 || s.res == NULL);
fetchdone(&s);
return error;
}
/*
* setlabel: set the descriptive label for the connection.
*
* we use simple pointer comparison for label equality check.
*/
static void
setlabel(struct Xconn *xc, const char *label)
{
int error;
/*
* put the label into application_name so that it's shown in
* pg_stat_activity. we are sure that our labels don't need
* PQescapeStringConn.
*
* example:
* SELECT pid,application_name,query FROM pg_stat_activity
* WHERE state <> 'idle'
*/
if (label != NULL && label != xc->label) {
struct cmd *c;
char cmd_str[1024];
snprintf(cmd_str, sizeof(cmd_str),
"SET application_name TO 'pgfs: %s'", label);
c = createcmd(cmd_str, CMD_NOPREPARE);
error = simplecmd(xc, c);
freecmd(c);
assert(error == 0);
xc->label = label;
} else {
#if 0 /* don't bother to clear label */
static struct cmd *c;
CREATECMD_NOPARAM(c, "SET application_name TO 'pgfs'");
error = simplecmd(xc, c);
assert(error == 0);
#endif
}
}
struct Xconn *
begin(struct puffs_usermount *pu, const char *label)
{
struct Xconn *xc = getxc(puffs_cc_getcc(pu));
static struct cmd *c;
int error;
setlabel(xc, label);
CREATECMD_NOPARAM(c, "BEGIN");
assert(!xc->in_trans);
error = simplecmd(xc, c);
assert(error == 0);
assert(PQtransactionStatus(xc->conn) == PQTRANS_INTRANS);
xc->in_trans = true;
return xc;
}
struct Xconn *
begin_readonly(struct puffs_usermount *pu, const char *label)
{
struct Xconn *xc = getxc(puffs_cc_getcc(pu));
static struct cmd *c;
int error;
setlabel(xc, label);
CREATECMD_NOPARAM(c, "BEGIN READ ONLY");
assert(!xc->in_trans);
error = simplecmd(xc, c);
assert(error == 0);
assert(PQtransactionStatus(xc->conn) == PQTRANS_INTRANS);
xc->in_trans = true;
return xc;
}
void
rollback(struct Xconn *xc)
{
PGTransactionStatusType status;
/*
* check the status as we are not sure the status of our transaction
* after a failed commit.
*/
status = PQtransactionStatus(xc->conn);
assert(status != PQTRANS_ACTIVE);
assert(status != PQTRANS_UNKNOWN);
if (status != PQTRANS_IDLE) {
static struct cmd *c;
int error;
assert(status == PQTRANS_INTRANS || status == PQTRANS_INERROR);
CREATECMD_NOPARAM(c, "ROLLBACK");
error = simplecmd(xc, c);
assert(error == 0);
}
DPRINTF("xc %p rollback %p\n", xc, xc->owner);
setlabel(xc, NULL);
relxc(xc);
}
int
commit(struct Xconn *xc)
{
static struct cmd *c;
int error;
CREATECMD_NOPARAM(c, "COMMIT");
error = simplecmd(xc, c);
setlabel(xc, NULL);
if (error == 0) {
DPRINTF("xc %p commit %p\n", xc, xc->owner);
relxc(xc);
}
return error;
}
int
commit_sync(struct Xconn *xc)
{
static struct cmd *c;
int error;
assert(!pgfs_dosync);
CREATECMD_NOPARAM(c, "SET LOCAL SYNCHRONOUS_COMMIT TO ON");
error = simplecmd(xc, c);
assert(error == 0);
return commit(xc);
}
static void
pgfs_notice_receiver(void *vp, const PGresult *res)
{
struct Xconn *xc = vp;
assert(PQresultStatus(res) == PGRES_NONFATAL_ERROR);
fprintf(stderr, "got a notice on %p\n", xc);
dumperror(xc, res);
}
static int
pgfs_readframe(struct puffs_usermount *pu, struct puffs_framebuf *pufbuf,
int fd, int *done)
{
struct Xconn *xc;
PGconn *conn;
TAILQ_FOREACH(xc, &xclist, list) {
if (PQsocket(xc->conn) == fd) {
break;
}
}
assert(xc != NULL);
conn = xc->conn;
PQconsumeInput(conn);
if (!PQisBusy(conn)) {
if (xc->blocker != NULL) {
DPRINTF("schedule %p\n", xc->blocker);
puffs_cc_schedule(xc->blocker);
} else {
DPRINTF("no blockers\n");
}
}
*done = 0;
return 0;
}
int
pgfs_connectdb(struct puffs_usermount *pu, const char *dbname,
const char *dbuser, bool debug, bool synchronous, unsigned int nconn)
{
const char *keywords[3+1];
const char *values[3];
unsigned int i;
if (nconn > 32) {
/*
* limit from sizeof(cmd->prepared_mask)
*/
return EINVAL;
}
if (debug) {
pgfs_dodprintf = true;
}
if (synchronous) {
pgfs_dosync = true;
}
i = 0;
if (dbname != NULL) {
keywords[i] = "dbname";
values[i] = dbname;
i++;
}
if (dbuser != NULL) {
keywords[i] = "user";
values[i] = dbuser;
i++;
}
keywords[i] = "application_name";
values[i] = "pgfs";
i++;
keywords[i] = NULL;
puffs_framev_init(pu, pgfs_readframe, NULL, NULL, NULL, NULL);
for (i = 0; i < nconn; i++) {
struct Xconn *xc;
struct Xconn *xc2;
static int xcid;
PGconn *conn;
struct cmd *c;
int error;
conn = PQconnectdbParams(keywords, values, 0);
if (conn == NULL) {
errx(EXIT_FAILURE,
"PQconnectdbParams: unknown failure");
}
if (PQstatus(conn) != CONNECTION_OK) {
/*
* XXX sleep and retry on ERRCODE_CANNOT_CONNECT_NOW
*/
errx(EXIT_FAILURE, "PQconnectdbParams: %s",
PQerrorMessage(conn));
}
DPRINTF("protocol version %d\n", PQprotocolVersion(conn));
puffs_framev_addfd(pu, PQsocket(conn), PUFFS_FBIO_READ);
xc = emalloc(sizeof(*xc));
xc->conn = conn;
xc->blocker = NULL;
xc->owner = NULL;
xc->in_trans = false;
xc->id = xcid++;
xc->label = NULL;
assert(xc->id < 32);
PQsetNoticeReceiver(conn, pgfs_notice_receiver, xc);
TAILQ_INSERT_HEAD(&xclist, xc, list);
xc2 = begin(pu, NULL);
assert(xc2 == xc);
c = createcmd("SET search_path TO pgfs", CMD_NOPREPARE);
error = simplecmd(xc, c);
assert(error == 0);
freecmd(c);
c = createcmd("SET SESSION CHARACTERISTICS AS "
"TRANSACTION ISOLATION LEVEL REPEATABLE READ",
CMD_NOPREPARE);
error = simplecmd(xc, c);
assert(error == 0);
freecmd(c);
c = createcmd("SET SESSION TIME ZONE UTC", CMD_NOPREPARE);
error = simplecmd(xc, c);
assert(error == 0);
freecmd(c);
if (!pgfs_dosync) {
c = createcmd("SET SESSION SYNCHRONOUS_COMMIT TO OFF",
CMD_NOPREPARE);
error = simplecmd(xc, c);
assert(error == 0);
freecmd(c);
}
if (debug) {
struct fetchstatus s;
static const Oid types[] = { INT8OID, };
uint64_t pid;
c = createcmd("SELECT pg_backend_pid()::int8;",
CMD_NOPREPARE);
error = sendcmd(xc, c);
assert(error == 0);
fetchinit(&s, xc);
error = FETCHNEXT(&s, types, &pid);
fetchdone(&s);
assert(error == 0);
DPRINTF("xc %p backend pid %" PRIu64 "\n", xc, pid);
}
error = commit(xc);
assert(error == 0);
assert(xc->owner == NULL);
}
/*
* XXX cleanup unlinked files here? what to do when the filesystem
* is shared?
*/
return 0;
}
struct waitq flushwaitq = TAILQ_HEAD_INITIALIZER(flushwaitq);
struct puffs_cc *flusher = NULL;
int
flush_xacts(struct puffs_usermount *pu)
{
struct puffs_cc *cc = puffs_cc_getcc(pu);
struct Xconn *xc;
static struct cmd *c;
uint64_t dummy;
int error;
/*
* flush all previously issued asynchronous transactions.
*
* XXX
* unfortunately it seems that there is no clean way to tell
* PostgreSQL flush XLOG. we could perform a CHECKPOINT but it's
* too expensive and overkill for our purpose.
* besides, PostgreSQL has an optimization to skip XLOG flushing
* for transactions which didn't produce WAL records.
* (changeset f6a0863e3cb72763490ceca2c558d5ef2dddd5f2)
* it means that an empty transaction ("BEGIN; COMMIT;"), which
* doesn't produce any WAL records, doesn't flush the XLOG even if
* synchronous_commit=on. we issues a dummy setval() to avoid the
* optimization.
* on the other hand, we try to avoid creating unnecessary WAL activity
* by serializing flushing and checking XLOG locations.
*/
assert(!pgfs_dosync);
if (flusher != NULL) { /* serialize flushers */
DPRINTF("%p flush in progress %p\n", cc, flusher);
waiton(&flushwaitq, cc);
assert(flusher == NULL);
}
DPRINTF("%p start flushing\n", cc);
flusher = cc;
retry:
xc = begin(pu, "flush");
CREATECMD_NOPARAM(c, "SELECT setval('dummyseq', 1) WHERE "
"pg_current_xlog_insert_location() <> pg_current_xlog_location()");
error = sendcmd(xc, c);
if (error != 0) {
goto got_error;
}
error = simplefetch(xc, INT8OID, &dummy);
assert(error != 0 || dummy == 1);
if (error == ENOENT) {
/*
* there seems to be nothing to flush.
*/
DPRINTF("%p no sync\n", cc);
error = 0;
}
if (error != 0) {
goto got_error;
}
error = commit_sync(xc);
if (error != 0) {
goto got_error;
}
goto done;
got_error:
rollback(xc);
if (error == EAGAIN) {
goto retry;
}
done:
assert(flusher == cc);
flusher = NULL;
wakeup_one(&flushwaitq);
DPRINTF("%p end flushing error=%d\n", cc, error);
return error;
}
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