modules/cache/mod_socache_dc.c

   1 /* Licensed to the Apache Software Foundation (ASF) under one or more
   2  * contributor license agreements.  See the NOTICE file distributed with
   3  * this work for additional information regarding copyright ownership.
   4  * The ASF licenses this file to You under the Apache License, Version 2.0
   5  * (the "License"); you may not use this file except in compliance with
   6  * the License.  You may obtain a copy of the License at
   7  *
   8  *     http://www.apache.org/licenses/LICENSE-2.0
   9  *
  10  * Unless required by applicable law or agreed to in writing, software
  11  * distributed under the License is distributed on an "AS IS" BASIS,
  12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13  * See the License for the specific language governing permissions and
  14  * limitations under the License.
  15  */
  16
  17 #include "httpd.h"
  18 #include "http_log.h"
  19 #include "http_request.h"
  20 #include "http_config.h"
  21 #include "http_protocol.h"
  22
  23 #include "apr_strings.h"
  24 #include "apr_time.h"
  25
  26 #include "ap_socache.h"
  27
  28 #include "distcache/dc_client.h"
  29
  30 #if !defined(DISTCACHE_CLIENT_API) || (DISTCACHE_CLIENT_API < 0x0001)
  31 #error "You must compile with a more recent version of the distcache-base package"
  32 #endif
  33
  34 struct ap_socache_instance_t {
  35     /* Configured target server: */
  36     const char *target;
  37     /* distcache client context: */
  38     DC_CTX *dc;
  39 };
  40
  41 static const char *socache_dc_create(ap_socache_instance_t **context,
  42                                      const char *arg,
  43                                      apr_pool_t *tmp, apr_pool_t *p)
  44 {
  45     struct ap_socache_instance_t *ctx;
  46
  47     ctx = *context = apr_palloc(p, sizeof *ctx);
  48
  49     ctx->target = apr_pstrdup(p, arg);
  50
  51     return NULL;
  52 }
  53
  54 static apr_status_t socache_dc_init(ap_socache_instance_t *ctx,
  55                                     const char *namespace,
  56                                     const struct ap_socache_hints *hints,
  57                                     server_rec *s, apr_pool_t *p)
  58 {
  59 #if 0
  60     /* If a "persistent connection" mode of operation is preferred, you *must*
  61      * also use the PIDCHECK flag to ensure fork()'d processes don't interlace
  62      * comms on the same connection as each other. */
  63 #define SESSION_CTX_FLAGS        SESSION_CTX_FLAG_PERSISTENT | \
  64                                  SESSION_CTX_FLAG_PERSISTENT_PIDCHECK | \
  65                                  SESSION_CTX_FLAG_PERSISTENT_RETRY | \
  66                                  SESSION_CTX_FLAG_PERSISTENT_LATE
  67 #else
  68     /* This mode of operation will open a temporary connection to the 'target'
  69      * for each cache operation - this makes it safe against fork()
  70      * automatically. This mode is preferred when running a local proxy (over
  71      * unix domain sockets) because overhead is negligable and it reduces the
  72      * performance/stability danger of file-descriptor bloatage. */
  73 #define SESSION_CTX_FLAGS        0
  74 #endif
  75     ctx->dc = DC_CTX_new(ctx->target, SESSION_CTX_FLAGS);
  76     if (!ctx->dc) {
  77         ap_log_error(APLOG_MARK, APLOG_ERR, 0, s, "distributed scache failed to obtain context");
  78         return APR_EGENERAL;
  79     }
  80     ap_log_error(APLOG_MARK, APLOG_INFO, 0, s, "distributed scache context initialised");
  81
  82     return APR_SUCCESS;
  83 }
  84
  85 static void socache_dc_kill(ap_socache_instance_t *ctx, server_rec *s)
  86 {
  87     if (ctx && ctx->dc) {
  88         DC_CTX_free(ctx->dc);
  89         ctx->dc = NULL;
  90     }
  91 }
  92
  93 static apr_status_t socache_dc_store(ap_socache_instance_t *ctx, server_rec *s,
  94                                      const unsigned char *id, unsigned int idlen,
  95                                      time_t timeout,
  96                                      unsigned char *der, unsigned int der_len,
  97                                      apr_pool_t *p)
  98 {
  99     /* !@#$%^ - why do we deal with *absolute* time anyway??? */
 100     timeout -= time(NULL);
 101     /* Send the serialised session to the distributed cache context */
 102     if (!DC_CTX_add_session(ctx->dc, id, idlen, der, der_len,
 103                             (unsigned long)timeout * 1000)) {
 104         ap_log_error(APLOG_MARK, APLOG_ERR, 0, s, "distributed scache 'add_session' failed");
 105         return APR_EGENERAL;
 106     }
 107     ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, s, "distributed scache 'add_session' successful");
 108     return APR_SUCCESS;
 109 }
 110
 111 static apr_status_t socache_dc_retrieve(ap_socache_instance_t *ctx, server_rec *s,
 112                                         const unsigned char *id, unsigned int idlen,
 113                                         unsigned char *dest, unsigned int *destlen,
 114                                         apr_pool_t *p)
 115 {
 116     unsigned int data_len;
 117
 118     /* Retrieve any corresponding session from the distributed cache context */
 119     if (!DC_CTX_get_session(ctx->dc, id, idlen, dest, *destlen, &data_len)) {
 120         ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, s, "distributed scache 'get_session' MISS");
 121         return APR_EGENERAL;
 122     }
 123     if (data_len > *destlen) {
 124         ap_log_error(APLOG_MARK, APLOG_ERR, 0, s, "distributed scache 'get_session' OVERFLOW");
 125         return APR_ENOSPC;
 126     }
 127     *destlen = data_len;
 128     ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, s, "distributed scache 'get_session' HIT");
 129     return APR_SUCCESS;
 130 }
 131
 132 static apr_status_t socache_dc_remove(ap_socache_instance_t *ctx,
 133                                       server_rec *s, const unsigned char *id,
 134                                       unsigned int idlen, apr_pool_t *p)
 135 {
 136     /* Remove any corresponding session from the distributed cache context */
 137     if (!DC_CTX_remove_session(ctx->dc, id, idlen)) {
 138         ap_log_error(APLOG_MARK, APLOG_ERR, 0, s, "distributed scache 'remove_session' MISS");
 139         return APR_NOTFOUND;
 140     } else {
 141         ap_log_error(APLOG_MARK, APLOG_ERR, 0, s, "distributed scache 'remove_session' HIT");
 142         return APR_SUCCESS;
 143     }
 144 }
 145
 146 static void socache_dc_status(ap_socache_instance_t *ctx, request_rec *r, int flags)
 147 {
 148     ap_log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r,
 149                   "distributed scache 'socache_dc_status'");
 150     ap_rprintf(r, "cache type: <b>DC (Distributed Cache)</b>, "
 151                " target: <b>%s</b><br>", ctx->target);
 152 }
 153
 154 static const ap_socache_provider_t socache_dc = {
 155     "distcache",
 156     0,
 157     socache_dc_create,
 158     socache_dc_init,
 159     socache_dc_kill,
 160     socache_dc_store,
 161     socache_dc_retrieve,
 162     socache_dc_remove,
 163     socache_dc_status
 164 };
 165
 166 static void register_hooks(apr_pool_t *p)
 167 {
 168     ap_register_provider(p, AP_SOCACHE_PROVIDER_GROUP, "dc",
 169                          AP_SOCACHE_PROVIDER_VERSION,
 170                          &socache_dc);
 171 }
 172
 173 module AP_MODULE_DECLARE_DATA socache_dc_module = {
 174     STANDARD20_MODULE_STUFF,
 175     NULL, NULL, NULL, NULL, NULL,
 176     register_hooks
 177 };
 178