Adjust socache init interface to take sizing hints, and namespace tag

for memcache:

* modules/cache/ap_socache.h (struct ap_socache_hints): New structure.
  Change init callback to take namespace string and hints structure pointer.

* modules/cache/mod_socache_dc.c (socache_dc_init): Adjust accordingly.

* modules/cache/mod_socache_dbm.c (struct ap_socache_instance_t): Rename
  timeout field to expiry_interval.
  (socache_dbm_init, socache_dbm_create): Take expiry interval from
  hints rather than hard-code to 30.
  (socache_dbm_expire): Update for timeout field rename.

* modules/cache/mod_socache_shmcb.c (socache_shmcb_init): Adjust for
  hints and namespace; adjust subcache index sizing heuristics to use
  passed-in hints.

* modules/cache/mod_socache_memcache.c (struct ap_socache_instance_t):
  Add tag, taglen fields.
  (socache_mc_init): Store the passed-in namespace in instance
  structure.
  (mc_session_id2sz): Adjust to not take context, use configured
  tag as string prefix, and not use a return value.
  (socache_mc_store, socache_mc_retrieve, socache_mc_remove):
  Adjust for mc_session_id2sz interface changes.

* modules/ssl/ssl_scache.c (ssl_scache_init): Pass namespace and hints
  to socache provider init function.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@645978 13f79535-47bb-0310-9956-ffa450edef68

modules/cache/ap_socache.h

@@ -39,6 +39,18 @@
 /* A cache instance. */
 typedef struct ap_socache_instance_t ap_socache_instance_t;
 
+/* Hints which may be passed to the init function; providers may
+ * ignore some or all of these hints. */
+struct ap_socache_hints {
+    /* Approximate average length of IDs: */
+    apr_size_t avg_id_len;
+    /* Approximate average size of objects: */
+    apr_size_t avg_obj_size;
+    /* Interval (in seconds) after which an expiry run is
+     * necessary. */
+    time_t expiry_interval;
+};
+
 typedef struct ap_socache_provider_t {
     /* Canonical provider name: */
     const char *name;
@@ -56,8 +68,11 @@ typedef struct ap_socache_provider_t {
      * first argument to subsequent invocations. */
     const char *(*create)(ap_socache_instance_t **instance, const char *arg, 
                           apr_pool_t *tmp, apr_pool_t *p);
-    /* Initialize the cache.  Return APR error code.   */
-    apr_status_t (*init)(ap_socache_instance_t *instance, /* hints, namespace */
+    /* Initialize the cache.  NAMESPACE must given a unique string
+     * prefix for use with memcached; if hints is non-NULL, it gives a
+     * set of hints for the provider.  Return APR error code.  */
+    apr_status_t (*init)(ap_socache_instance_t *instance, const char *namespace, 
+                         const struct ap_socache_hints *hints,
                          server_rec *s, apr_pool_t *pool);
     /* Destroy a given cache context. */    
     void (*destroy)(ap_socache_instance_t *instance, server_rec *s);

modules/cache/mod_socache_dbm.c

@@ -41,7 +41,7 @@ struct ap_socache_instance_t {
     /* Pool must only be used with the mutex held. */
     apr_pool_t *pool;
     time_t last_expiry;
-    time_t timeout;
+    time_t expiry_interval;
 };
 
 /**
@@ -81,13 +81,15 @@ static const char *socache_dbm_create(ap_socache_instance_t **context,
     if (!ctx->data_file) {
         return apr_psprintf(tmp, "Invalid cache file path %s", arg);
     }
-    ctx->timeout = 30; /* ### take as hint in _init */
+
     apr_pool_create(&ctx->pool, p);
 
     return NULL;
 }
 
 static apr_status_t socache_dbm_init(ap_socache_instance_t *ctx, 
+                                     const char *namespace, 
+                                     const struct ap_socache_hints *hints,
                                      server_rec *s, apr_pool_t *p)
 {
     apr_dbm_t *dbm;
@@ -112,6 +114,9 @@ static apr_status_t socache_dbm_init(ap_socache_instance_t *ctx,
     }
     apr_dbm_close(dbm);
 
+    ctx->expiry_interval = (hints && hints->expiry_interval 
+                            ? hints->expiry_interval : 30);
+
 #if !defined(OS2) && !defined(WIN32) && !defined(BEOS) && !defined(NETWARE)
     /*
      * We have to make sure the Apache child processes have access to
@@ -345,7 +350,7 @@ static void socache_dbm_expire(ap_socache_instance_t *ctx, server_rec *s)
      */
     tNow = time(NULL);
 
-    if (tNow < ctx->last_expiry + ctx->timeout) {
+    if (tNow < ctx->last_expiry + ctx->expiry_interval) {
         return;
     }
 

modules/cache/mod_socache_dc.c

@@ -51,7 +51,10 @@ static const char *socache_dc_create(ap_socache_instance_t **context,
     return NULL;
 }
 
-static apr_status_t socache_dc_init(ap_socache_instance_t *ctx, server_rec *s, apr_pool_t *p)
+static apr_status_t socache_dc_init(ap_socache_instance_t *ctx, 
+                                    const char *namespace, 
+                                    const struct ap_socache_hints *hints, 
+                                    server_rec *s, apr_pool_t *p)
 {
 #if 0
     /* If a "persistent connection" mode of operation is preferred, you *must*

modules/cache/mod_socache_memcache.c

@@ -35,10 +35,6 @@
 #include "apr_memcache.h"
 
 /* The underlying apr_memcache system is thread safe.. */
-#define MC_TAG "mod_ssl:"
-#define MC_TAG_LEN \
-    (sizeof(MC_TAG))
-
 #define MC_KEY_LEN 254
 
 #ifndef MC_DEFAULT_SERVER_PORT
@@ -61,6 +57,8 @@
 struct ap_socache_instance_t {
     const char *servers;
     apr_memcache_t *mc;
+    const char *tag;
+    apr_size_t taglen;
 };
 
 static const char *socache_mc_create(ap_socache_instance_t **context, 
@@ -77,6 +75,8 @@ static const char *socache_mc_create(ap_socache_instance_t **context,
 }
 
 static apr_status_t socache_mc_init(ap_socache_instance_t *ctx, 
+                                    const char *namespace,
+                                    const struct ap_socache_hints *hints,
                                     server_rec *s, apr_pool_t *p)
 {
     apr_status_t rv;
@@ -156,6 +156,9 @@ static apr_status_t socache_mc_init(ap_socache_instance_t *ctx,
         split = apr_strtok(NULL,",", &tok);
     }
 
+    ctx->tag = apr_pstrcat(p, namespace, ":", NULL);
+    ctx->taglen = strlen(ctx->tag);
+
     return APR_SUCCESS;
 }
 
@@ -164,22 +167,21 @@ static void socache_mc_kill(ap_socache_instance_t *context, server_rec *s)
     /* noop. */
 }
 
-static char *mc_session_id2sz(const unsigned char *id, unsigned int idlen,
-                              char *str, int strsize)
+static void mc_session_id2sz(ap_socache_instance_t *ctx,
+                             const unsigned char *id, unsigned int idlen,
+                             char *buf, apr_size_t buflen)
 {
+    apr_size_t maxlen = (buflen - ctx->taglen) / 2;
     char *cp;
     int n;
-    int maxlen = (strsize - MC_TAG_LEN)/2;
 
-    cp = apr_cpystrn(str, MC_TAG, MC_TAG_LEN);
+    cp = apr_cpystrn(buf, ctx->tag, ctx->taglen);
     for (n = 0; n < idlen && n < maxlen; n++) {
         apr_snprintf(cp, 3, "%02X", (unsigned) id[n]);
         cp += 2;
     }
 
     *cp = '\0';
-
-    return str;
 }
 
 static apr_status_t socache_mc_store(ap_socache_instance_t *ctx, server_rec *s, 
@@ -188,21 +190,16 @@ static apr_status_t socache_mc_store(ap_socache_instance_t *ctx, server_rec *s,
                                      unsigned char *ucaData, unsigned int nData)
 {
     char buf[MC_KEY_LEN];
-    char *strkey = NULL;
     apr_status_t rv;
 
-    strkey = mc_session_id2sz(id, idlen, buf, sizeof(buf));
-    if(!strkey) {
-        ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, s, "scache_mc: Key generation borked.");
-        return APR_EGENERAL;
-    }
+    mc_session_id2sz(ctx, id, idlen, buf, sizeof(buf));
 
-    rv = apr_memcache_set(ctx->mc, strkey, (char*)ucaData, nData, timeout, 0);
+    rv = apr_memcache_set(ctx->mc, buf, (char*)ucaData, nData, timeout, 0);
 
     if (rv != APR_SUCCESS) {
         ap_log_error(APLOG_MARK, APLOG_CRIT, rv, s,
                      "scache_mc: error setting key '%s' "
-                     "with %d bytes of data", strkey, nData);
+                     "with %d bytes of data", buf, nData);
         return rv;
     }
 
@@ -217,21 +214,14 @@ static apr_status_t socache_mc_retrieve(ap_socache_instance_t *ctx,
 {
     apr_size_t der_len;
     char buf[MC_KEY_LEN], *der;
-    char *strkey = NULL;
     apr_status_t rv;
 
-    strkey = mc_session_id2sz(id, idlen, buf, sizeof(buf));
-
-    if (!strkey) {
-        ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, s,
-                     "scache_mc: Key generation borked.");
-        return APR_EGENERAL;
-    }
+    mc_session_id2sz(ctx, id, idlen, buf, sizeof(buf));
 
     /* ### this could do with a subpool, but _getp looks like it will
      * eat memory like it's going out of fashion anyway. */
 
-    rv = apr_memcache_getp(ctx->mc, p, strkey,
+    rv = apr_memcache_getp(ctx->mc, p, buf,
                            &der, &der_len, NULL);
     if (rv) {
         if (rv != APR_NOTFOUND) {
@@ -257,21 +247,16 @@ static void socache_mc_remove(ap_socache_instance_t *ctx, server_rec *s,
                               apr_pool_t *p)
 {
     char buf[MC_KEY_LEN];
-    char* strkey = NULL;
     apr_status_t rv;
 
-    strkey = mc_session_id2sz(id, idlen, buf, sizeof(buf));
-    if(!strkey) {
-        ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, s, "scache_mc: Key generation borked.");
-        return;
-    }
+    mc_session_id2sz(ctx, id, idlen, buf, sizeof(buf));
 
-    rv = apr_memcache_delete(ctx->mc, strkey, 0);
+    rv = apr_memcache_delete(ctx->mc, buf, 0);
 
     if (rv != APR_SUCCESS) {
         ap_log_error(APLOG_MARK, APLOG_DEBUG, rv, s,
                      "scache_mc: error deleting key '%s' ",
-                     strkey);
+                     buf);
         return;
     }
 }

modules/cache/mod_socache_shmcb.c

@@ -302,6 +302,8 @@ static const char *socache_shmcb_create(ap_socache_instance_t **context,
 }
 
 static apr_status_t socache_shmcb_init(ap_socache_instance_t *ctx,
+                                       const char *namespace, 
+                                       const struct ap_socache_hints *hints,
                                        server_rec *s, apr_pool_t *p)
 {
     void *shm_segment;
@@ -309,6 +311,7 @@ static apr_status_t socache_shmcb_init(ap_socache_instance_t *ctx,
     apr_status_t rv;
     SHMCBHeader *header;
     unsigned int num_subcache, num_idx, loop;
+    apr_size_t avg_obj_size, avg_id_len;
 
     /* Create shared memory segment */
     if (ctx->data_file == NULL) {
@@ -348,16 +351,10 @@ static apr_status_t socache_shmcb_init(ap_socache_instance_t *ctx,
                  shm_segsize);
     /* Discount the header */
     shm_segsize -= sizeof(SHMCBHeader);
-    /* Select the number of subcaches to create and how many indexes each
-     * should contain based on the size of the memory (the header has already
-     * been subtracted). Typical non-client-auth sslv3/tlsv1 sessions are
-     * around 180 bytes (148 bytes data and 32 bytes for the id), so
-     * erring to division by 150 helps ensure we would exhaust data
-     * storage before index storage (except sslv2, where it's
-     * *slightly* the other way). From there, we select the number of
-     * subcaches to be a power of two, such that the number of indexes
-     * per subcache at least twice the number of subcaches. */
-    num_idx = (shm_segsize) / 150;
+    /* Select index size based on average object size hints, if given. */
+    avg_obj_size = hints && hints->avg_obj_size ? hints->avg_obj_size : 150;
+    avg_id_len = hints && hints->avg_id_len ? hints->avg_id_len : 30;
+    num_idx = (shm_segsize) / (avg_obj_size + avg_id_len);
     num_subcache = 256;
     while ((num_idx / num_subcache) < (2 * num_subcache))
         num_subcache /= 2;

modules/ssl/ssl_scache.c

@@ -43,6 +43,7 @@ void ssl_scache_init(server_rec *s, apr_pool_t *p)
     apr_status_t rv;
     void *data;
     const char *userdata_key = "ssl_scache_init";
+    struct ap_socache_hints hints;
     
     /* The very first invocation of this function will be the
      * post_config invocation during server startup; do nothing for
@@ -67,7 +68,12 @@ void ssl_scache_init(server_rec *s, apr_pool_t *p)
         return;
     }
 
-    rv = mc->sesscache->init(mc->sesscache_context, s, p);
+    memset(&hints, 0, sizeof hints);
+    hints.avg_obj_size = 150;
+    hints.avg_id_len = 30;
+    hints.expiry_interval = 30;
+    
+    rv = mc->sesscache->init(mc->sesscache_context, "mod_ssl", &hints, s, p);
     if (rv) {
         /* ABORT ABORT etc. */
         ssl_die();