postfix-2.2-20040729

postfix/HISTORY

@@ -9583,12 +9583,12 @@ Apologies for any names omitted.
 	recvmsg(). Workaround is to insert an intervening read
 	(write) operation.  Presumably, LINUX 2.4 is confusing the
 	data and file descriptor.  Lucky Ralf Hildebrandt.  Files:
-	util/sys_defs.h, global/scache_clnt,c, scache/scache.c.
+	util/sys_defs.h, global/scache_clnt.c, scache/scache.c.
 
 20040723
 
 	Bug? Safety? spawn(8) did not reject a user with the -1
-	UID value, so the command was running as root.  Files:
+	UID value, so the command could run as root.  Files:
 	util/spawn_command.c, src/util/spawn.c.
 
 	User interface: parameter smtp_connection_cache_domains
@@ -9599,6 +9599,18 @@ Apologies for any names omitted.
 	Bugfix: "421 Timeout exceeded" wasn't guarded by setjmp().
 	Victor Duchovni, Morgan Stanley. File: smtpd/smtpd.c.
 
+20040729
+
+	Feature:  enable SMTP session caching temporarily while a
+	site has a high volume of mail in the active queue.
+	Parameter:  smtp_connection_cache_on_demand (default:
+	yes).  Files:  smtp/smtp_connect.c, *qmgr/qmgr_entry.c,
+	*qmgr/qmgr_queue.c, *qmgr/qmgr_deliver.c.
+
+	Feature: smtp-source -N option to generate unique recipient
+	addresses for (trivial-rewrite) stress testing. Victor
+	Duchovni, Morgan Stanley. File: smtpstone/smtp-source.c.
+
 Open problems:
 
 	Low: update events.c so that 1-second timer requests do

postfix/RELEASE_NOTES

@@ -7,14 +7,30 @@ snapshot release).  Patches are issued for the official release
 and change the patchlevel and the release date. Patches are never
 issued for snapshot releases.
 
+Incompatible changes with snapshot Postfix-2.2-20040729
+=======================================================
+
+SMTP session caching is enabled temporarily when a destination has
+a high volume of mail in the active queue.  To disable, specify
+"smtp_connection_cache_on_demand = no".
+
+Major changes with snapshot Postfix-2.2-20040729
+================================================
+
+Opportunistic SMTP session caching. When a destination has a high
+volume of mail in the active queue, SMTP session caching is enabled
+temporarily.  This is controlled with a new configuration parameter
+"smtp_connection_cache_on_demand" (default:  yes).
+
 Incompatible changes with snapshot Postfix-2.2-20040723
 =======================================================
 
-Session caching is enabled with smtp_session_cache_destinations,
+Permanent SMTP session caching is now enabled with the
-and requires "bare" domain names without "[]" or TCP port.  This
+smtp_session_cache_destinations parameter. This requires "bare"
-eliminates a syntax conflict between host:port and maptype:mapname,
+domain names without "[]" or TCP port.  The change eliminates a
-and simplifies the user interface, at the cost of a minor loss of
+syntax conflict between host:port and maptype:mapname, and simplifies
-control over what sessions are cached.
+the user interface, at the cost of a minor loss of control over
+what sessions are cached.
 
 Major changes with snapshot Postfix-2.2-20040721
 ================================================
@@ -38,10 +54,10 @@ The default SMTP/LMTP timeouts for sending RSET are reduced to 20s.
 Major changes with snapshot Postfix-2.2-20040720
 ================================================
 
-Selective SMTP session caching. Instead of disconnecting immediately
+Selective permanent SMTP session caching. Instead of disconnecting
-after a mail transaction, the SMTP client can save the open session
+immediately after a mail transaction, the SMTP client can save the
-to a session cache daemon, so that any SMTP client process can use
+open session to a session cache daemon, so that any SMTP client
-that session for another mail transaction.
+process can use that session for another mail transaction.
 
 This feature introduces the scache (session cache) server, which
 is added to your master.cf file when you upgrade Postfix.

postfix/html/postconf.5.html

@@ -5169,10 +5169,10 @@ The default time unit is s (seconds).
 <DT><b><a name="smtp_connection_cache_destinations">smtp_connection_cache_destinations</a>
 (default: empty)</b></DT><DD>
 
-<p> The SMTP destinations for which SMTP connection caching is
+<p> Permanently enable SMTP connection caching for the specified
-enabled.  With SMTP connection caching, a connection is not closed
+destinations.  With SMTP connection caching, a connection is not
-immediately after completion of a mail transaction.  Instead, the
+closed immediately after completion of a mail transaction.  Instead,
-connection is kept open for up to $<a href="postconf.5.html#smtp_connection_cache_time_limit">smtp_connection_cache_time_limit</a>
+the connection is kept open for up to $<a href="postconf.5.html#smtp_connection_cache_time_limit">smtp_connection_cache_time_limit</a>
 seconds.  This allows connections to be reused for other deliveries,
 and can improve mail delivery performance. </p>
 
@@ -5200,6 +5200,22 @@ ignored.
 <p></p>
 
 
+</DD>
+
+<DT><b><a name="smtp_connection_cache_on_demand">smtp_connection_cache_on_demand</a>
+(default: yes)</b></DT><DD>
+
+<p> Temporarily enable SMTP session caching while a destination
+has a high volume of mail in the <a href="QSHAPE_README.html#active_queue">active queue</a>.  With SMTP connection
+caching, a connection is not closed immediately after completion
+of a mail transaction.  Instead, the connection is kept open for
+up to $<a href="postconf.5.html#smtp_connection_cache_time_limit">smtp_connection_cache_time_limit</a> seconds.  This allows
+connections to be reused for other deliveries, and can improve mail
+delivery performance. </p>
+
+<p> This feature is available in Postfix 2.2 and later. </p>
+
+
 </DD>
 
 <DT><b><a name="smtp_connection_cache_reuse_limit">smtp_connection_cache_reuse_limit</a>

postfix/html/smtp-source.1.html

@@ -52,6 +52,13 @@ SMTP-SOURCE(1)                                     SMTP-SOURCE(1)
        <b>-m</b> <i>message</i><b>_</b><i>count</i>
               Send the specified number of messages (default: 1).
 
+       <b>-N</b>     Prepend  a  non-repeating  sequence  number to each
+              recipient address. This avoids the artificial  100%
+              hit  rate  in the resolve and rewrite client caches
+              and exercises the  trivial-rewrite  daemon,  better
+              approximating  Postfix  performance under real-life
+              work-loads.
+
        <b>-r</b> <i>recipient</i><b>_</b><i>count</i>
               Send the specified number of recipients per  trans-
               action (default: 1).  Recipient names are generated

postfix/html/smtp.8.html

@@ -37,7 +37,12 @@ SMTP(8)                                                   SMTP(8)
        After  a  successful  mail  transaction,  a session may be
        saved to the <a href="scache.8.html"><b>scache(8)</a></b> session cache server,  so  that  it
        may  be  used by any SMTP client for a subsequent transac-
-       tion.  Session caching is disabled by default.
+       tion.
+
+       By default, session caching  is  enabled  temporarily  for
+       destinations that have a high volume of mail in the active
+       queue. Session caching can be enabled permanently for spe-
+       cific destinations.
 
 <b>SECURITY</b>
        The SMTP client is moderately security-sensitive. It talks
@@ -237,8 +242,13 @@ SMTP(8)                                                   SMTP(8)
        Available in Postfix version 2.2 and later:
 
        <b><a href="postconf.5.html#smtp_connection_cache_destinations">smtp_connection_cache_destinations</a> (empty)</b>
-              The SMTP destinations  for  which  SMTP  connection
+              Permanently  enable SMTP connection caching for the
-              caching is enabled.
+              specified destinations.
+
+       <b>smtp_connection_cache_on_demand (yes)</b>
+              Temporarily enable SMTP  session  caching  while  a
+              destination has a high volume of mail in the active
+              queue.
 
        <b><a href="postconf.5.html#smtp_connection_cache_reuse_limit">smtp_connection_cache_reuse_limit</a> (10)</b>
               When SMTP session caching is enabled, the number of

postfix/man/man1/smtp-source.1

@@ -45,6 +45,12 @@ include message headers.
 Speak LMTP rather than SMTP.
 .IP "\fB-m \fImessage_count\fR"
 Send the specified number of messages (default: 1).
+.IP "\fB-N\fR"
+Prepend a non-repeating sequence number to each recipient
+address. This avoids the artificial 100% hit rate in the
+resolve and rewrite client caches and exercises the
+trivial-rewrite daemon, better approximating Postfix
+performance under real-life work-loads.
 .IP "\fB-r \fIrecipient_count\fR"
 Send the specified number of recipients per transaction (default: 1).
 Recipient names are generated by prepending a number to the

postfix/man/man5/postconf.5

@@ -2698,10 +2698,10 @@ the operating system).
 Time units: s (seconds), m (minutes), h (hours), d (days), w (weeks).
 The default time unit is s (seconds).
 .SH smtp_connection_cache_destinations (default: empty)
-The SMTP destinations for which SMTP connection caching is
+Permanently enable SMTP connection caching for the specified
-enabled.  With SMTP connection caching, a connection is not closed
+destinations.  With SMTP connection caching, a connection is not
-immediately after completion of a mail transaction.  Instead, the
+closed immediately after completion of a mail transaction.  Instead,
-connection is kept open for up to $smtp_connection_cache_time_limit
+the connection is kept open for up to $smtp_connection_cache_time_limit
 seconds.  This allows connections to be reused for other deliveries,
 and can improve mail delivery performance.
 .PP
@@ -2721,6 +2721,16 @@ a "type:table" with domains and/or relay hosts on the left-hand
 side.  The right-hand side result from "type:table" lookups is
 ignored.
 .PP
+.SH smtp_connection_cache_on_demand (default: yes)
+Temporarily enable SMTP session caching while a destination
+has a high volume of mail in the active queue.  With SMTP connection
+caching, a connection is not closed immediately after completion
+of a mail transaction.  Instead, the connection is kept open for
+up to $smtp_connection_cache_time_limit seconds.  This allows
+connections to be reused for other deliveries, and can improve mail
+delivery performance.
+.PP
+This feature is available in Postfix 2.2 and later.
 .SH smtp_connection_cache_reuse_limit (default: 10)
 When SMTP session caching is enabled, the number of times that
 an SMTP session is reused before it is closed.

postfix/man/man8/smtp.8

@@ -35,7 +35,11 @@ deliver the mail to an alternate host.
 After a successful mail transaction, a session may be saved
 to the \fBscache(8)\fR session cache server, so that it
 may be used by any SMTP client for a subsequent transaction.
-Session caching is disabled by default.
+
+By default, session caching is enabled temporarily for
+destinations that have a high volume of mail in the active
+queue. Session caching can be enabled permanently for
+specific destinations.
 .SH "SECURITY"
 .na
 .nf
@@ -210,8 +214,11 @@ for receiving the server response.
 .PP
 Available in Postfix version 2.2 and later:
 .IP "\fBsmtp_connection_cache_destinations (empty)\fR"
-The SMTP destinations for which SMTP connection caching is
+Permanently enable SMTP connection caching for the specified
-enabled.
+destinations.
+.IP "\fBsmtp_connection_cache_on_demand (yes)\fR"
+Temporarily enable SMTP session caching while a destination
+has a high volume of mail in the active queue.
 .IP "\fBsmtp_connection_cache_reuse_limit (10)\fR"
 When SMTP session caching is enabled, the number of times that
 an SMTP session is reused before it is closed.

postfix/proto/postconf.proto

@@ -3187,10 +3187,10 @@ an SMTP session is reused before it is closed.
 
 %PARAM smtp_connection_cache_destinations
 
-<p> The SMTP destinations for which SMTP connection caching is
+<p> Permanently enable SMTP connection caching for the specified
-enabled.  With SMTP connection caching, a connection is not closed
+destinations.  With SMTP connection caching, a connection is not
-immediately after completion of a mail transaction.  Instead, the
+closed immediately after completion of a mail transaction.  Instead,
-connection is kept open for up to $smtp_connection_cache_time_limit
+the connection is kept open for up to $smtp_connection_cache_time_limit
 seconds.  This allows connections to be reused for other deliveries,
 and can improve mail delivery performance. </p>
 
@@ -3217,6 +3217,18 @@ ignored.
 
 <p></p>
 
+%PARAM smtp_connection_cache_on_demand yes
+
+<p> Temporarily enable SMTP session caching while a destination
+has a high volume of mail in the active queue.  With SMTP connection
+caching, a connection is not closed immediately after completion
+of a mail transaction.  Instead, the connection is kept open for
+up to $smtp_connection_cache_time_limit seconds.  This allows
+connections to be reused for other deliveries, and can improve mail
+delivery performance. </p>
+
+<p> This feature is available in Postfix 2.2 and later. </p>
+
 %PARAM smtp_connect_timeout 30s
 
 <p>

postfix/src/global/deliver_request.h

@@ -62,6 +62,7 @@ typedef struct DELIVER_REQUEST {
 #define DEL_REQ_FLAG_VERIFY	(1<<8)	/* verify recipient, don't deliver */
 #define DEL_REQ_FLAG_EXPAND	(1<<9)	/* verify expansion, don't deliver */
 #define DEL_REQ_FLAG_RECORD	(1<<10)	/* record and deliver */
+#define DEL_REQ_FLAG_SCACHE	(1<<11)	/* opportunistic caching */
 
 #define DEL_REQ_TRACE_FLAGS_MASK \
 	(DEL_REQ_FLAG_VERIFY | DEL_REQ_FLAG_EXPAND | DEL_REQ_FLAG_RECORD)

postfix/src/global/mail_params.h

@@ -781,6 +781,10 @@ extern int var_smtp_reuse_limit;
 #define DEF_SMTP_CACHE_DEST	""
 extern char *var_smtp_cache_dest;
 
+#define VAR_SMTP_CACHE_DEMAND	"smtp_connection_cache_on_demand"
+#define DEF_SMTP_CACHE_DEMAND	1
+extern bool var_smtp_cache_demand;
+
 #define VAR_SMTP_CONN_TMOUT	"smtp_connect_timeout"
 #define DEF_SMTP_CONN_TMOUT	"30s"
 extern int var_smtp_conn_tmout;

postfix/src/global/mail_version.h

@@ -20,7 +20,7 @@
   * Patches change the patchlevel and the release date. Snapshots change the
   * release date only.
   */
-#define MAIL_RELEASE_DATE	"20040723"
+#define MAIL_RELEASE_DATE	"20040729"
 #define MAIL_VERSION_NUMBER	"2.2"
 
 #define VAR_MAIL_VERSION	"mail_version"

postfix/src/oqmgr/Makefile.in

@@ -155,6 +155,9 @@ qmgr_entry.o: ../../include/events.h
 qmgr_entry.o: ../../include/vstream.h
 qmgr_entry.o: ../../include/vbuf.h
 qmgr_entry.o: ../../include/mail_params.h
+qmgr_entry.o: ../../include/deliver_request.h
+qmgr_entry.o: ../../include/vstring.h
+qmgr_entry.o: ../../include/recipient_list.h
 qmgr_entry.o: qmgr.h
 qmgr_entry.o: ../../include/scan_dir.h
 qmgr_message.o: qmgr_message.c

postfix/src/oqmgr/qmgr.h

@@ -140,6 +140,7 @@ struct QMGR_ENTRY_LIST {
 };
 
 struct QMGR_QUEUE {
+    int     dflags;			/* delivery request options */
     char   *name;			/* domain name or address */
     char   *nexthop;			/* domain name */
     int     todo_refcount;		/* queue entries (todo list) */

postfix/src/oqmgr/qmgr_deliver.c

@@ -143,6 +143,7 @@ static int qmgr_deliver_send_request(QMGR_ENTRY *entry, VSTREAM *stream)
     }
 
     flags = message->tflags
+	| entry->queue->dflags
 	| (message->inspect_xport ? DEL_REQ_FLAG_BOUNCE : DEL_REQ_FLAG_DEFLT);
     attr_print(stream, ATTR_FLAG_MORE,
 	       ATTR_TYPE_NUM, MAIL_ATTR_FLAGS, flags,

postfix/src/oqmgr/qmgr_entry.c

@@ -84,6 +84,7 @@
 /* Global library. */
 
 #include <mail_params.h>
+#include <deliver_request.h>		/* opportunistic session caching */
 
 /* Application-specific. */
 
@@ -187,6 +188,7 @@ void    qmgr_entry_done(QMGR_ENTRY *entry, int which)
 
 QMGR_ENTRY *qmgr_entry_create(QMGR_QUEUE *queue, QMGR_MESSAGE *message)
 {
+    char   *myname = "qmgr_entry_create";
     QMGR_ENTRY *entry;
 
     /*
@@ -207,6 +209,22 @@ QMGR_ENTRY *qmgr_entry_create(QMGR_QUEUE *queue, QMGR_MESSAGE *message)
     QMGR_LIST_APPEND(queue->todo, entry);
     queue->todo_refcount++;
 
+    /*
+     * With opportunistic session caching, the delivery agent must not only
+     * 1) save a session upon completion, but also 2) reuse a cached session
+     * upon the next delivery request. In order to not miss out on 2), we
+     * have to make caching sticky or else we get silly behavior when the
+     * in-memory queue drains. New connections must not be made while cached
+     * connections aren't being reused.
+     */
+    if ((queue->dflags & DEL_REQ_FLAG_SCACHE) == 0
+	&& queue->window < queue->todo_refcount + queue->busy_refcount) {
+	if (msg_verbose)
+	    msg_info("%s: passing on-demand session caching threshold for %s",
+		     myname, queue->name);
+	queue->dflags |= DEL_REQ_FLAG_SCACHE;
+    }
+
     /*
      * Warn if a destination is falling behind while the active queue
      * contains a non-trivial amount of single-recipient email. When a

postfix/src/oqmgr/qmgr_queue.c

@@ -183,6 +183,7 @@ void    qmgr_queue_throttle(QMGR_QUEUE *queue, const char *reason)
 	queue->reason = mystrdup(reason);
 	event_request_timer(qmgr_queue_unthrottle_wrapper,
 			    (char *) queue, var_min_backoff_time);
+	queue->dflags = 0;
     }
 }
 
@@ -254,6 +255,7 @@ QMGR_QUEUE *qmgr_queue_create(QMGR_TRANSPORT *transport, const char *name,
 
     queue = (QMGR_QUEUE *) mymalloc(sizeof(QMGR_QUEUE));
     qmgr_queue_count++;
+    queue->dflags = 0;
     queue->name = mystrdup(name);
     queue->nexthop = mystrdup(nexthop);
     queue->todo_refcount = 0;

postfix/src/qmgr/Makefile.in

@@ -157,6 +157,9 @@ qmgr_entry.o: ../../include/events.h
 qmgr_entry.o: ../../include/vstream.h
 qmgr_entry.o: ../../include/vbuf.h
 qmgr_entry.o: ../../include/mail_params.h
+qmgr_entry.o: ../../include/deliver_request.h
+qmgr_entry.o: ../../include/vstring.h
+qmgr_entry.o: ../../include/recipient_list.h
 qmgr_entry.o: qmgr.h
 qmgr_entry.o: ../../include/scan_dir.h
 qmgr_job.o: qmgr_job.c

postfix/src/qmgr/qmgr.h

@@ -176,6 +176,7 @@ struct QMGR_ENTRY_LIST {
 };
 
 struct QMGR_QUEUE {
+    int     dflags;			/* delivery request options */
     char   *name;			/* domain name or address */
     char   *nexthop;			/* domain name */
     int     todo_refcount;		/* queue entries (todo list) */

postfix/src/qmgr/qmgr_deliver.c

@@ -148,6 +148,7 @@ static int qmgr_deliver_send_request(QMGR_ENTRY *entry, VSTREAM *stream)
     }
 
     flags = message->tflags
+	| entry->queue->dflags
 	| (message->inspect_xport ? DEL_REQ_FLAG_BOUNCE : DEL_REQ_FLAG_DEFLT);
     attr_print(stream, ATTR_FLAG_MORE,
 	       ATTR_TYPE_NUM, MAIL_ATTR_FLAGS, flags,

postfix/src/qmgr/qmgr_entry.c

@@ -92,6 +92,7 @@
 /* Global library. */
 
 #include <mail_params.h>
+#include <deliver_request.h>		/* opportunistic session caching */
 
 /* Application-specific. */
 
@@ -244,6 +245,7 @@ void    qmgr_entry_done(QMGR_ENTRY *entry, int which)
 
 QMGR_ENTRY *qmgr_entry_create(QMGR_PEER *peer, QMGR_MESSAGE *message)
 {
+    char   *myname = "qmgr_entry_create";
     QMGR_ENTRY *entry;
     QMGR_QUEUE *queue = peer->queue;
 
@@ -268,6 +270,22 @@ QMGR_ENTRY *qmgr_entry_create(QMGR_PEER *peer, QMGR_MESSAGE *message)
     QMGR_LIST_APPEND(queue->todo, entry, queue_peers);
     queue->todo_refcount++;
 
+    /*
+     * With opportunistic session caching, the delivery agent must not only
+     * 1) save a session upon completion, but also 2) reuse a cached session
+     * upon the next delivery request. In order to not miss out on 2), we
+     * have to make caching sticky or else we get silly behavior when the
+     * in-memory queue drains. New connections must not be made while cached
+     * connections aren't being reused.
+     */
+    if ((queue->dflags & DEL_REQ_FLAG_SCACHE) == 0
+	&& queue->window < queue->todo_refcount + queue->busy_refcount) {
+	if (msg_verbose)
+	    msg_info("%s: passing on-demand session caching threshold for %s",
+		     myname, queue->name);
+	queue->dflags |= DEL_REQ_FLAG_SCACHE;
+    }
+
     /*
      * Warn if a destination is falling behind while the active queue
      * contains a non-trivial amount of single-recipient email. When a

postfix/src/qmgr/qmgr_queue.c

@@ -181,6 +181,7 @@ void    qmgr_queue_throttle(QMGR_QUEUE *queue, const char *reason)
 	queue->reason = mystrdup(reason);
 	event_request_timer(qmgr_queue_unthrottle_wrapper,
 			    (char *) queue, var_min_backoff_time);
+	queue->dflags = 0;
     }
 }
 
@@ -231,6 +232,7 @@ QMGR_QUEUE *qmgr_queue_create(QMGR_TRANSPORT *transport, const char *name,
 
     queue = (QMGR_QUEUE *) mymalloc(sizeof(QMGR_QUEUE));
     qmgr_queue_count++;
+    queue->dflags = 0;
     queue->name = mystrdup(name);
     queue->nexthop = mystrdup(nexthop);
     queue->todo_refcount = 0;

postfix/src/smtp/smtp.c

@@ -29,7 +29,11 @@
 /*	After a successful mail transaction, a session may be saved
 /*	to the \fBscache(8)\fR session cache server, so that it
 /*	may be used by any SMTP client for a subsequent transaction.
-/*	Session caching is disabled by default.
+/*
+/*	By default, session caching is enabled temporarily for
+/*	destinations that have a high volume of mail in the active
+/*	queue. Session caching can be enabled permanently for
+/*	specific destinations.
 /* SECURITY
 /* .ad
 /* .fi
@@ -184,8 +188,11 @@
 /* .PP
 /*	Available in Postfix version 2.2 and later:
 /* .IP "\fBsmtp_connection_cache_destinations (empty)\fR"
-/*	The SMTP destinations for which SMTP connection caching is
+/*	Permanently enable SMTP connection caching for the specified
-/*	enabled.
+/*	destinations.
+/* .IP "\fBsmtp_connection_cache_on_demand (yes)\fR"
+/*	Temporarily enable SMTP session caching while a destination
+/*	has a high volume of mail in the active queue.
 /* .IP "\fBsmtp_connection_cache_reuse_limit (10)\fR"
 /*	When SMTP session caching is enabled, the number of times that
 /*	an SMTP session is reused before it is closed.
@@ -374,6 +381,7 @@ int     var_smtp_cache_conn;
 int     var_smtp_reuse_limit;
 char   *var_smtp_cache_dest;
 char   *var_scache_service;
+bool    var_smtp_cache_demand;
 
  /*
   * Global variables. smtp_errno is set by the address lookup routines and by
@@ -489,7 +497,7 @@ static void post_init(char *unused_name, char **unused_argv)
     /*
      * Session cache instance.
      */
-    if (*var_smtp_cache_dest)
+    if (*var_smtp_cache_dest || var_smtp_cache_demand)
 #if 0
 	smtp_scache = scache_multi_create();
 #else
@@ -601,6 +609,7 @@ int     main(int argc, char **argv)
 	VAR_SMTP_QUOTE_821_ENV, DEF_SMTP_QUOTE_821_ENV, &var_smtp_quote_821_env,
 	VAR_SMTP_DEFER_MXADDR, DEF_SMTP_DEFER_MXADDR, &var_smtp_defer_mxaddr,
 	VAR_SMTP_SEND_XFORWARD, DEF_SMTP_SEND_XFORWARD, &var_smtp_send_xforward,
+	VAR_SMTP_CACHE_DEMAND, DEF_SMTP_CACHE_DEMAND, &var_smtp_cache_demand,
 	0,
     };
 

postfix/src/smtp/smtp_connect.c

@@ -521,10 +521,14 @@ int     smtp_connect(SMTP_STATE *state)
 	 * :port, because : is already used for maptype:mapname. Because of
 	 * this limitation we use the bare domain without the optional [] or
 	 * non-default TCP port.
+	 * 
+	 * Opportunistic (a.k.a. on-demand) session caching on request by the
+	 * queue manager. This is turned temporarily when a destination has a
+	 * high volume of mail in the active queue.
 	 */
 	if (cpp == sites->argv
-	    && smtp_cache_dest
+	    && ((request->flags & DEL_REQ_FLAG_SCACHE) != 0
-	    && string_list_match(smtp_cache_dest, domain)) {
+		|| (smtp_cache_dest && string_list_match(smtp_cache_dest, domain)))) {
 	    sess_flags |= SMTP_SESS_FLAG_CACHE;
 	    SET_NEXTHOP_STATE(state, lookup_mx, domain, port);
 	}

postfix/src/smtpstone/smtp-source.c

@@ -39,6 +39,12 @@
 /*	Speak LMTP rather than SMTP.
 /* .IP "\fB-m \fImessage_count\fR"
 /*	Send the specified number of messages (default: 1).
+/* .IP "\fB-N\fR"
+/*	Prepend a non-repeating sequence number to each recipient
+/*	address. This avoids the artificial 100% hit rate in the
+/*	resolve and rewrite client caches and exercises the
+/*	trivial-rewrite daemon, better approximating Postfix
+/*	performance under real-life work-loads.
 /* .IP "\fB-r \fIrecipient_count\fR"
 /*	Send the specified number of recipients per transaction (default: 1).
 /*	Recipient names are generated by prepending a number to the
@@ -171,6 +177,7 @@ static int random_delay = 0;
 static int fixed_delay = 0;
 static int talk_lmtp = 0;
 static char *subject = 0;
+static int number_rcpts = 0;
 
 static void enqueue_connect(SESSION *);
 static void start_connect(SESSION *);
@@ -573,9 +580,10 @@ static void send_rcpt(int unused_event, char *context)
     if ((except = vstream_setjmp(session->stream)) != 0)
 	msg_fatal("%s while sending recipient", exception_text(except));
 
-    if (session->rcpt_count > 1)
+    if (session->rcpt_count > 1 || number_rcpts > 0)
 	command(session->stream, "RCPT TO:<%d%s>",
-		session->rcpt_count, recipient);
+		number_rcpts ? number_rcpts++ : session->rcpt_count,
+		recipient);
     else
 	command(session->stream, "RCPT TO:<%s>", recipient);
     session->rcpt_count--;
@@ -767,7 +775,7 @@ static void quit_done(int unused_event, char *context)
 
 static void usage(char *myname)
 {
-    msg_fatal("usage: %s -s sess -l msglen -m msgs -c -C count -d -f from -o -t to -r rcptcount -R delay -v -w delay host[:port]", myname);
+    msg_fatal("usage: %s -cdLNov -s sess -l msglen -m msgs -C count -f from -t to -r rcptcount -R delay -w delay host[:port]", myname);
 }
 
 /* main - parse JCL and start the machine */
@@ -789,7 +797,7 @@ int     main(int argc, char **argv)
     /*
      * Parse JCL.
      */
-    while ((ch = GETOPT(argc, argv, "cC:df:l:Lm:or:R:s:S:t:vw:")) > 0) {
+    while ((ch = GETOPT(argc, argv, "cC:df:l:Lm:Nor:R:s:S:t:vw:")) > 0) {
 	switch (ch) {
 	case 'c':
 	    count++;
@@ -822,6 +830,9 @@ int     main(int argc, char **argv)
 	    if ((message_count = atoi(optarg)) <= 0)
 		msg_fatal("bad message count: %s", optarg);
 	    break;
+	case 'N':
+	    number_rcpts = 1;
+	    break;
 	case 'o':
 	    send_helo_first = 0;
 	    send_headers = 0;