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Work around broken cache management in mod_ldap: If LDAPSharedCacheSize is too

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small, try to free some memory by purging the cache and log a warning.

Also increase the default LDAPSharedCacheSize to 500000. This is a more
realistic size suitable for the default values of 1024 for LdapCacheEntries and
LdapOpCacheEntries.

PR: 46749


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@822458 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Stefan Fritsch
2009-10-06 19:39:38 +00:00
parent eded0f9d2d
commit da0e12aacf
4 changed files with 65 additions and 11 deletions
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6
CHANGES
View File

@@ -10,6 +10,12 @@ Changes with Apache 2.3.3
mod_proxy_ftp: NULL pointer dereference on error paths.
[Stefan Fritsch <sf fritsch.de>, Joe Orton]
*) mod_ldap: If LDAPSharedCacheSize is too small, try harder to purge
some cache entries and log a warning. Also increase the default
LDAPSharedCacheSize to 500000. This is a more realistic size suitable
for the default values of 1024 for LdapCacheEntries/LdapOpCacheEntries.
PR 46749. [Stefan Fritsch]
*) mod_rewrite: Make sure that a hostname:port isn't fully qualified if
the request is a CONNECT request. [Bill Zajac <billz consultla.com>]

6
docs/manual/mod/mod_ldap.xml
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@@ -67,7 +67,7 @@ by other LDAP modules</description>
# be loaded. Change the "yourdomain.example.com" to<br />
# match your domain.<br />
<br />
LDAPSharedCacheSize 200000<br />
LDAPSharedCacheSize 500000<br />
LDAPCacheEntries 1024<br />
LDAPCacheTTL 600<br />
LDAPOpCacheEntries 1024<br />
@@ -412,12 +412,12 @@ by other LDAP modules</description>
<name>LDAPSharedCacheSize</name>
<description>Size in bytes of the shared-memory cache</description>
<syntax>LDAPSharedCacheSize <var>bytes</var></syntax>
<default>LDAPSharedCacheSize 102400</default>
<default>LDAPSharedCacheSize 500000</default>
<contextlist><context>server config</context></contextlist>
<usage>
<p>Specifies the number of bytes to allocate for the shared
memory cache. The default is 100kb. If set to 0, shared memory
memory cache. The default is 500kb. If set to 0, shared memory
caching will not be used.</p>
</usage>
</directivesynopsis>

2
modules/ldap/util_ldap.c
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@@ -2402,7 +2402,7 @@ static void *util_ldap_create_config(apr_pool_t *p, server_rec *s)
apr_thread_mutex_create(&st->mutex, APR_THREAD_MUTEX_DEFAULT, st->pool);
#endif
st->cache_bytes = 100000;
st->cache_bytes = 500000;
st->search_cache_ttl = 600000000;
st->search_cache_size = 1024;
st->compare_cache_ttl = 600000000;

56
modules/ldap/util_ldap_cache_mgr.c
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@@ -442,6 +442,7 @@ void *util_ald_cache_fetch(util_ald_cache_t *cache, void *payload)
void *util_ald_cache_insert(util_ald_cache_t *cache, void *payload)
{
unsigned long hashval;
void *tmp_payload;
util_cache_node_t *node;
/* sanity check */
@@ -454,21 +455,68 @@ void *util_ald_cache_insert(util_ald_cache_t *cache, void *payload)
util_ald_cache_purge(cache);
if (cache->numentries >= cache->maxentries) {
/* if the purge was not effective, we leave now to avoid an overflow */
ap_log_error(APLOG_MARK, APLOG_ERR, 0, NULL,
"Purge of LDAP cache failed");
return NULL;
}
}
/* should be safe to add an entry */
if ((node = (util_cache_node_t *)util_ald_alloc(cache, sizeof(util_cache_node_t))) == NULL) {
node = (util_cache_node_t *)util_ald_alloc(cache,
sizeof(util_cache_node_t));
if (node == NULL) {
/*
* XXX: The cache management should be rewritten to work
* properly when LDAPSharedCacheSize is too small.
*/
ap_log_error(APLOG_MARK, APLOG_WARNING, 0, NULL,
"LDAPSharedCacheSize is too small. Increase it or "
"reduce LDAPCacheEntries/LDAPOpCacheEntries!");
if (cache->numentries < cache->fullmark) {
/*
* We have not even reached fullmark, trigger a complete purge.
* This is still better than not being able to add new entries
* at all.
*/
cache->marktime = apr_time_now();
}
util_ald_cache_purge(cache);
node = (util_cache_node_t *)util_ald_alloc(cache,
sizeof(util_cache_node_t));
if (node == NULL) {
ap_log_error(APLOG_MARK, APLOG_ERR, 0, NULL,
"Could not allocate memory for LDAP cache entry");
return NULL;
}
}
/* Take a copy of the payload before proceeeding. */
payload = (*cache->copy)(cache, payload);
if (!payload) {
tmp_payload = (*cache->copy)(cache, payload);
if (tmp_payload == NULL) {
/*
* XXX: The cache management should be rewritten to work
* properly when LDAPSharedCacheSize is too small.
*/
ap_log_error(APLOG_MARK, APLOG_WARNING, 0, NULL,
"LDAPSharedCacheSize is too small. Increase it or "
"reduce LDAPCacheEntries/LDAPOpCacheEntries!");
if (cache->numentries < cache->fullmark) {
/*
* We have not even reached fullmark, trigger a complete purge.
* This is still better than not being able to add new entries
* at all.
*/
cache->marktime = apr_time_now();
}
util_ald_cache_purge(cache);
tmp_payload = (*cache->copy)(cache, payload);
if (tmp_payload == NULL) {
ap_log_error(APLOG_MARK, APLOG_ERR, 0, NULL,
"Could not allocate memory for LDAP cache value");
util_ald_free(cache, node);
return NULL;
}
}
payload = tmp_payload;
/* populate the entry */
cache->inserts++;