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Postgres FD Implementation
Commit 8362be35 authored by Tom Lane's avatar Tom Lane
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Code review for superuser_reserved_connections patch. Don't try to do 

database access outside a transaction; revert bogus performance improvement
in SIBackendInit(); improve comments; add documentation (this part courtesy
Neil Conway).
parent 02d83d75
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Showing with 90 additions and 63 deletions
doc/src/sgml/runtime.sgml
View file @ 8362be35
<!--
$Header: /cvsroot/pgsql/doc/src/sgml/runtime.sgml,v 1.157 2002/11/21 00:42:18 tgl Exp $
$Header: /cvsroot/pgsql/doc/src/sgml/runtime.sgml,v 1.158 2002/11/21 06:36:08 tgl Exp $
-->
<Chapter Id="runtime">
......@@ -1902,6 +1902,28 @@ dynamic_library_path = '/usr/local/lib/postgresql:/home/my_project/lib:$libdir'
</listitem>
</varlistentry>
<varlistentry>
<term><varname>SUPERUSER_RESERVED_CONNECTIONS</varname>
(<type>integer</type>)</term>
<listitem>
<para>
Determines the number of <quote>connection slots</quote> that
are reserved for connections by <productname>PostgreSQL</>
superusers. At most <varname>max_connections</> connections can
ever be active simultaneously. Whenever the number of active
concurrent connections is at least <varname>max_connections</> minus
<varname>superuser_reserved_connections</varname>, new connections
will be accepted only from superuser accounts.
</para>
<para>
The default value is 2. The value must be less than the value of
<varname>max_connections</varname>. This parameter can only be
set at server start.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><varname>TCPIP_SOCKET</varname> (<type>boolean</type>)</term>
<listitem>
......@@ -2952,24 +2974,25 @@ $ <userinput>kill -INT `head -1 /usr/local/pgsql/data/postmaster.pid`</userinput
</para>
<para>
With SSL support compiled in, the <productname>PostgreSQL</> server
can be started with SSL support by setting the parameter
<varname>ssl</varname> to on in
<filename>postgresql.conf</filename>. When starting in SSL mode,
the server will look for the files <filename>server.key</> and
<filename>server.crt</> in the data directory. These files should
contain the server private key and certificate respectively. These
files must be set up correctly before an SSL-enabled server can
start. If the private key is protected with a passphrase, the
server will prompt for the passphrase and will not start until it
has been entered.
With <acronym>SSL</> support compiled in, the
<productname>PostgreSQL</> server can be started with
<acronym>SSL</> support by setting the parameter
<varname>ssl</varname> to on in <filename>postgresql.conf</>. When
starting in <acronym>SSL</> mode, the server will look for the
files <filename>server.key</> and <filename>server.crt</> in the
data directory. These files should contain the server private key
and certificate respectively. These files must be set up correctly
before an <acronym>SSL</>-enabled server can start. If the private key is
protected with a passphrase, the server will prompt for the
passphrase and will not start until it has been entered.
</para>
<para>
The server will listen for both standard and SSL connections on the
same TCP/IP port, and will negotiate with any connecting client on
whether to use SSL. See <xref linkend="client-authentication"> about
how to force the server to only use of SSL for certain connections.
The server will listen for both standard and <acronym>SSL</>
connections on the same TCP/IP port, and will negotiate with any
connecting client on whether to use <acronym>SSL</>. See <xref
linkend="client-authentication"> about how to force the server to
require use of <acronym>SSL</> for certain connections.
</para>
<para>
......
src/backend/postmaster/postmaster.c
View file @ 8362be35
......@@ -37,7 +37,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/postmaster/postmaster.c,v 1.298 2002/11/18 00:40:46 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/postmaster/postmaster.c,v 1.299 2002/11/21 06:36:08 tgl Exp $
*
* NOTES
*
......@@ -154,12 +154,11 @@ int MaxBackends = DEF_MAXBACKENDS;
/*
* ReservedBackends is the number of backends reserved for superuser use.
* This number is taken out of the pool size given by MaxBackends so
* number of backend slots available to none super users is
* (MaxBackends - ReservedBackends). Note, existing super user
* connections are not taken into account once this lower limit has
* been reached, i.e. superuser connections made before the lower limit
* is reached always count towards that limit and are not taken from
* ReservedBackends.
* number of backend slots available to non-superusers is
* (MaxBackends - ReservedBackends). Note what this really means is
* "if there are <= ReservedBackends connections available, only superusers
* can make new connections" --- pre-existing superuser connections don't
* count against the limit.
*/
int ReservedBackends = 2;
......@@ -568,7 +567,15 @@ PostmasterMain(int argc, char *argv[])
}
/*
* Check for invalid combinations of switches
* Now we can set the data directory, and then read postgresql.conf.
*/
checkDataDir(potential_DataDir); /* issues error messages */
SetDataDir(potential_DataDir);
ProcessConfigFile(PGC_POSTMASTER);
/*
* Check for invalid combinations of GUC settings.
*/
if (NBuffers < 2 * MaxBackends || NBuffers < 16)
{
......@@ -581,16 +588,11 @@ PostmasterMain(int argc, char *argv[])
ExitPostmaster(1);
}
checkDataDir(potential_DataDir); /* issues error messages */
SetDataDir(potential_DataDir);
ProcessConfigFile(PGC_POSTMASTER);
/*
* Force an exit if ReservedBackends is not less than MaxBackends.
*/
if (ReservedBackends >= MaxBackends)
elog(FATAL, "superuser_reserved_connections must be less than max_connections.");
{
postmaster_error("superuser_reserved_connections must be less than max_connections.");
ExitPostmaster(1);
}
/*
* Now that we are done processing the postmaster arguments, reset
......
src/backend/storage/ipc/sinval.c
View file @ 8362be35
......@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/storage/ipc/sinval.c,v 1.52 2002/09/04 20:31:25 momjian Exp $
* $Header: /cvsroot/pgsql/src/backend/storage/ipc/sinval.c,v 1.53 2002/11/21 06:36:08 tgl Exp $
*
*-------------------------------------------------------------------------
*/
......@@ -542,12 +542,11 @@ BackendIdGetProc(BackendId procId)
/*
* CountEmptyBackendSlots - count empty slots in backend process table
*
* Doesn't count since the procState array could be large and we've already
* allowed for that by running a freeBackends counter in the SI segment.
* Unlike CountActiveBackends() we do not need to interrogate the
* backends to determine the free slot count.
* Goes for a lock despite being a trival look up in case other backends
* are busy starting or exiting since there is scope for confusion.
* We don't actually need to count, since sinvaladt.c maintains a
* freeBackends counter in the SI segment.
*
* Acquiring the lock here is almost certainly overkill, but just in
* case fetching an int is not atomic on your machine ...
*/
int
CountEmptyBackendSlots(void)
......
src/backend/storage/ipc/sinvaladt.c
View file @ 8362be35
......@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/storage/ipc/sinvaladt.c,v 1.48 2002/08/29 21:02:12 momjian Exp $
* $Header: /cvsroot/pgsql/src/backend/storage/ipc/sinvaladt.c,v 1.49 2002/11/21 06:36:08 tgl Exp $
*
*-------------------------------------------------------------------------
*/
......@@ -92,13 +92,6 @@ SIBackendInit(SISeg *segP)
int index;
ProcState *stateP = NULL;
if (segP->freeBackends == 0)
{
/* out of procState slots */
MyBackendId = InvalidBackendId;
return 0;
}
/* Look for a free entry in the procState array */
for (index = 0; index < segP->lastBackend; index++)
{
......@@ -111,9 +104,18 @@ SIBackendInit(SISeg *segP)
if (stateP == NULL)
{
stateP = &segP->procState[segP->lastBackend];
Assert(stateP->nextMsgNum < 0);
segP->lastBackend++;
if (segP->lastBackend < segP->maxBackends)
{
stateP = &segP->procState[segP->lastBackend];
Assert(stateP->nextMsgNum < 0);
segP->lastBackend++;
}
else
{
/* out of procState slots */
MyBackendId = InvalidBackendId;
return 0;
}
}
MyBackendId = (stateP - &segP->procState[0]) + 1;
......
src/backend/utils/init/postinit.c
View file @ 8362be35
......@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/utils/init/postinit.c,v 1.117 2002/10/03 19:19:09 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/utils/init/postinit.c,v 1.118 2002/11/21 06:36:08 tgl Exp $
*
*
*-------------------------------------------------------------------------
......@@ -377,6 +377,18 @@ InitPostgres(const char *dbname, const char *username)
*/
RelationCacheInitializePhase3();
/*
* Check a normal user hasn't connected to a superuser reserved slot.
* We can't do this till after we've read the user information, and
* we must do it inside a transaction since checking superuserness
* may require database access. The superuser check is probably the
* most expensive part; don't do it until necessary.
*/
if (ReservedBackends > 0 &&
CountEmptyBackendSlots() < ReservedBackends &&
!superuser())
elog(FATAL, "Non-superuser connection limit exceeded");
/*
* Initialize various default states that can't be set up until we've
* selected the active user and done ReverifyMyDatabase.
......@@ -397,17 +409,6 @@ InitPostgres(const char *dbname, const char *username)
/* close the transaction we started above */
if (!bootstrap)
CommitTransactionCommand(true);
/*
* Check a normal user hasn't connected to a superuser reserved slot.
* Do this here since we need the user information and that only
* happens after we've started bringing the shared memory online. So
* we wait until we've registered exit handlers and potentially shut
* an open transaction down for an as safety conscious rejection as
* possible.
*/
if (CountEmptyBackendSlots() < ReservedBackends && !superuser())
elog(ERROR, "Non-superuser connection limit exceeded");
}
/*
......
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