diff --git a/docs/manual/mod/mod_session.html.en b/docs/manual/mod/mod_session.html.en
index 6834f8e..9f8301f 100644
--- a/docs/manual/mod/mod_session.html.en
+++ b/docs/manual/mod/mod_session.html.en
@@ -82,6 +82,7 @@
<li><img alt="" src="../images/down.gif" /> <a href="#sessionheader">SessionHeader</a></li>
<li><img alt="" src="../images/down.gif" /> <a href="#sessioninclude">SessionInclude</a></li>
<li><img alt="" src="../images/down.gif" /> <a href="#sessionmaxage">SessionMaxAge</a></li>
+<li><img alt="" src="../images/down.gif" /> <a href="#sessionexpiryupdateinterval">SessionExpiryUpdateInterval</a></li>
</ul>
<h3>Bugfix checklist</h3><ul class="seealso"><li><a href="https://www.apache.org/dist/httpd/CHANGES_2.4">httpd changelog</a></li><li><a href="https://bz.apache.org/bugzilla/buglist.cgi?bug_status=__open__&list_id=144532&product=Apache%20httpd-2&query_format=specific&order=changeddate%20DESC%2Cpriority%2Cbug_severity&component=mod_session">Known issues</a></li><li><a href="https://bz.apache.org/bugzilla/enter_bug.cgi?product=Apache%20httpd-2&component=mod_session">Report a bug</a></li></ul><h3>See also</h3>
<ul class="seealso">
@@ -482,6 +483,37 @@ AuthName realm
<p>Setting the maxage to zero disables session expiry.</p>
+</div>
+<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
+<div class="directive-section"><h2><a name="SessionExpiryUpdateInterval" id="sessionexpiryupdateinterval">SessionExpiryUpdateInterval</a> <a name="sessionexpiryupdateinterval" id="sessionexpiryupdateinterval">Directive</a></h2>
+<table class="directive">
+<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Define the number of seconds a session's expiry may change without the session being updated</td></tr>
+<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>SessionExpiryUpdateInterval <var>interval</var></code></td></tr>
+<tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>SessionExpiryUpdateInterval 0 (always update)</code></td></tr>
+<tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
+<tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_session</td></tr>
+</table>
+ <p>The <code class="directive">SessionExpiryUpdateInterval</code> directive allows
+ sessions to avoid the cost associated with writing the session each request
+ when only the expiry time has changed. This can be used to make a website
+ more efficient or reduce load on a database when using
+ <module>mod_session_dbd</module>. The session is always written if the data
+ stored in the session has changed or the expiry has changed by more than the
+ configured interval.</p>
+
+ <p>Setting the interval to zero disables this directive, and the session
+ expiry is refreshed for each request.</p>
+
+ <p>This directive only has an effect when combined with <code class="directive"><a href="../mod/mod_session.html#sessionmaxage">SessionMaxAge</a></code> to enable session
+ expiry. Sessions without an expiry are only written when the data stored in
+ the session has changed.</p>
+
+ <div class="warning"><h3>Warning</h3>
+ <p>Because the session expiry may not be refreshed with each request, it's
+ possible for sessions to expire up to <var>interval</var> seconds early.
+ Using a small interval usually provides sufficient savings while having a
+ minimal effect on expiry resolution.</p></div>
+
</div>
</div>
<div class="bottomlang">
diff --git a/modules/session/mod_session.c b/modules/session/mod_session.c
index d517020..10e6396 100644
--- a/modules/session/mod_session.c
+++ b/modules/session/mod_session.c
@@ -177,6 +177,7 @@ static apr_status_t ap_session_save(request_rec * r, session_rec * z)
{
if (z) {
apr_time_t now = apr_time_now();
+ apr_time_t initialExpiry = z->expiry;
int rv = 0;
session_dir_conf *dconf = ap_get_module_config(r->per_dir_config,
@@ -207,6 +208,17 @@ static apr_status_t ap_session_save(request_rec * r, session_rec * z)
z->expiry = now + z->maxage * APR_USEC_PER_SEC;
}
+ /* don't save if the only change is the expiry by a small amount */
+ if (!z->dirty && dconf->expiry_update_time
+ && (z->expiry - initialExpiry < dconf->expiry_update_time)) {
+ return APR_SUCCESS;
+ }
+
+ /* also don't save sessions that didn't change at all */
+ if (!z->dirty && !z->maxage) {
+ return APR_SUCCESS;
+ }
+
/* encode the session */
rv = ap_run_session_encode(r, z);
if (OK != rv) {
@@ -553,6 +565,10 @@ static void *merge_session_dir_config(apr_pool_t * p, void *basev, void *addv)
new->env_set = add->env_set || base->env_set;
new->includes = apr_array_append(p, base->includes, add->includes);
new->excludes = apr_array_append(p, base->excludes, add->excludes);
+ new->expiry_update_time = (add->expiry_update_set == 0)
+ ? base->expiry_update_time
+ : add->expiry_update_time;
+ new->expiry_update_set = add->expiry_update_set || base->expiry_update_set;
return new;
}
@@ -622,6 +638,21 @@ static const char *add_session_exclude(cmd_parms * cmd, void *dconf, const char
return NULL;
}
+static const char *
+ set_session_expiry_update(cmd_parms * parms, void *dconf, const char *arg)
+{
+ session_dir_conf *conf = dconf;
+
+ conf->expiry_update_time = atoi(arg);
+ if (conf->expiry_update_time < 0) {
+ return "SessionExpiryUpdateInterval must be positive or nul";
+ }
+ conf->expiry_update_time = apr_time_from_sec(conf->expiry_update_time);
+ conf->expiry_update_set = 1;
+
+ return NULL;
+}
+
static const command_rec session_cmds[] =
{
@@ -637,6 +668,9 @@ static const command_rec session_cmds[] =
"URL prefixes to include in the session. Defaults to all URLs"),
AP_INIT_TAKE1("SessionExclude", add_session_exclude, NULL, RSRC_CONF|OR_AUTHCFG,
"URL prefixes to exclude from the session. Defaults to no URLs"),
+ AP_INIT_TAKE1("SessionExpiryUpdateInterval", set_session_expiry_update, NULL, RSRC_CONF|OR_AUTHCFG,
+ "time interval for which a session's expiry time may change "
+ "without having to be rewritten. Zero to disable"),
{NULL}
};
diff --git a/modules/session/mod_session.h b/modules/session/mod_session.h
index a6dd5e9..bdeb532 100644
--- a/modules/session/mod_session.h
+++ b/modules/session/mod_session.h
@@ -115,6 +115,9 @@ typedef struct {
* URLs included if empty */
apr_array_header_t *excludes; /* URL prefixes to be excluded. No
* URLs excluded if empty */
+ apr_time_t expiry_update_time; /* seconds the session expiry may change and
+ * not have to be rewritten */
+ int expiry_update_set;
} session_dir_conf;
/**
diff --git a/modules/session/mod_session_cookie.c b/modules/session/mod_session_cookie.c
index 6a02322..4aa75e4 100644
--- a/modules/session/mod_session_cookie.c
+++ b/modules/session/mod_session_cookie.c
@@ -60,9 +60,6 @@ static apr_status_t session_cookie_save(request_rec * r, session_rec * z)
session_cookie_dir_conf *conf = ap_get_module_config(r->per_dir_config,
&session_cookie_module);
- /* don't cache auth protected pages */
- apr_table_addn(r->headers_out, "Cache-Control", "no-cache");
-
/* create RFC2109 compliant cookie */
if (conf->name_set) {
if (z->encoded && z->encoded[0]) {
@@ -162,6 +159,9 @@ static apr_status_t session_cookie_load(request_rec * r, session_rec ** z)
/* put the session in the notes so we don't have to parse it again */
apr_table_setn(m->notes, note, (char *)zz);
+ /* don't cache auth protected pages */
+ apr_table_addn(r->headers_out, "Cache-Control", "no-cache, private");
+
return OK;
}
diff --git a/modules/session/mod_session_dbd.c b/modules/session/mod_session_dbd.c
index 0be7306..f683da2 100644
--- a/modules/session/mod_session_dbd.c
+++ b/modules/session/mod_session_dbd.c
@@ -245,6 +245,9 @@ static apr_status_t session_dbd_load(request_rec * r, session_rec ** z)
/* put the session in the notes so we don't have to parse it again */
apr_table_setn(m->notes, note, (char *)zz);
+ /* don't cache pages with a session */
+ apr_table_addn(r->headers_out, "Cache-Control", "no-cache, private");
+
return OK;
}
@@ -409,9 +412,6 @@ static apr_status_t session_dbd_save(request_rec * r, session_rec * z)
if (conf->name_set || conf->name2_set) {
char *oldkey = NULL, *newkey = NULL;
- /* don't cache pages with a session */
- apr_table_addn(r->headers_out, "Cache-Control", "no-cache");
-
/* if the session is new or changed, make a new session ID */
if (z->uuid) {
oldkey = apr_pcalloc(r->pool, APR_UUID_FORMATTED_LENGTH + 1);
@@ -458,7 +458,7 @@ static apr_status_t session_dbd_save(request_rec * r, session_rec * z)
else if (conf->peruser) {
/* don't cache pages with a session */
- apr_table_addn(r->headers_out, "Cache-Control", "no-cache");
+ apr_table_addn(r->headers_out, "Cache-Control", "no-cache, private");
if (r->user) {
ret = dbd_save(r, r->user, r->user, z->encoded, z->expiry);