diff options
Diffstat (limited to 'modules/cache/mod_cache.h')
| -rw-r--r-- | modules/cache/mod_cache.h | 68 |
1 files changed, 59 insertions, 9 deletions
diff --git a/modules/cache/mod_cache.h b/modules/cache/mod_cache.h index 72653ae3..eca42c01 100644 --- a/modules/cache/mod_cache.h +++ b/modules/cache/mod_cache.h @@ -24,7 +24,7 @@ */ #ifndef MOD_CACHE_H -#define MOD_CACHE_H +#define MOD_CACHE_H #define CORE_PRIVATE @@ -86,9 +86,13 @@ #define DEFAULT_CACHE_MAXEXPIRE MSEC_ONE_DAY #define DEFAULT_CACHE_EXPIRE MSEC_ONE_HR #define DEFAULT_CACHE_LMFACTOR (0.1) +#define DEFAULT_CACHE_MAXAGE 5 +#define DEFAULT_CACHE_LOCKPATH "/mod_cache-lock" +#define CACHE_LOCKNAME_KEY "mod_cache-lockname" +#define CACHE_LOCKFILE_KEY "mod_cache-lockfile" -/* Create a set of PROXY_DECLARE(type), PROXY_DECLARE_NONSTD(type) and - * PROXY_DECLARE_DATA with appropriate export and import tags for the platform +/* Create a set of CACHE_DECLARE(type), CACHE_DECLARE_NONSTD(type) and + * CACHE_DECLARE_DATA with appropriate export and import tags for the platform */ #if !defined(WIN32) #define CACHE_DECLARE(type) type @@ -134,7 +138,7 @@ typedef struct { int factor_set; /** ignore the last-modified header when deciding to cache this request */ int no_last_mod_ignore_set; - int no_last_mod_ignore; + int no_last_mod_ignore; /** ignore client's requests for uncached responses */ int ignorecachecontrol; int ignorecachecontrol_set; @@ -159,6 +163,13 @@ typedef struct { #define CACHE_IGNORE_SESSION_ID_SET 1 #define CACHE_IGNORE_SESSION_ID_UNSET 0 int ignore_session_id_set; + /* thundering herd lock */ + int lock; + int lock_set; + const char *lockpath; + int lockpath_set; + apr_time_t lockmaxage; + int lockmaxage_set; } cache_server_conf; /* cache info information */ @@ -173,11 +184,11 @@ struct cache_info { /* cache handle information */ -/* XXX TODO On the next structure change/MMN bump, +/* XXX TODO On the next structure change/MMN bump, * count must become an apr_off_t, representing * the potential size of disk cached objects. * Then dig for - * "XXX Bad Temporary Cast - see cache_object_t notes" + * "XXX Bad Temporary Cast - see cache_object_t notes" */ typedef struct cache_object cache_object_t; struct cache_object { @@ -206,7 +217,7 @@ typedef struct { apr_status_t (*store_headers)(cache_handle_t *h, request_rec *r, cache_info *i); apr_status_t (*store_body)(cache_handle_t *h, request_rec *r, apr_bucket_brigade *b); apr_status_t (*recall_headers) (cache_handle_t *h, request_rec *r); - apr_status_t (*recall_body) (cache_handle_t *h, apr_pool_t *p, apr_bucket_brigade *bb); + apr_status_t (*recall_body) (cache_handle_t *h, apr_pool_t *p, apr_bucket_brigade *bb); int (*create_entity) (cache_handle_t *h, request_rec *r, const char *urlkey, apr_off_t len); int (*open_entity) (cache_handle_t *h, request_rec *r, @@ -260,6 +271,45 @@ CACHE_DECLARE(apr_time_t) ap_cache_current_age(cache_info *info, const apr_time_ CACHE_DECLARE(int) ap_cache_check_freshness(cache_handle_t *h, request_rec *r); /** + * Try obtain a cache wide lock on the given cache key. + * + * If we return APR_SUCCESS, we obtained the lock, and we are clear to + * proceed to the backend. If we return APR_EEXISTS, the the lock is + * already locked, someone else has gone to refresh the backend data + * already, so we must return stale data with a warning in the mean + * time. If we return anything else, then something has gone pear + * shaped, and we allow the request through to the backend regardless. + * + * This lock is created from the request pool, meaning that should + * something go wrong and the lock isn't deleted on return of the + * request headers from the backend for whatever reason, at worst the + * lock will be cleaned up when the request is dies or finishes. + * + * If something goes truly bananas and the lock isn't deleted when the + * request dies, the lock will be trashed when its max-age is reached, + * or when a request arrives containing a Cache-Control: no-cache. At + * no point is it possible for this lock to permanently deny access to + * the backend. + */ +CACHE_DECLARE(apr_status_t) ap_cache_try_lock(cache_server_conf *conf, + request_rec *r, char *key); + +/** + * Remove the cache lock, if present. + * + * First, try to close the file handle, whose delete-on-close should + * kill the file. Otherwise, just delete the file by name. + * + * If no lock name has yet been calculated, do the calculation of the + * lock name first before trying to delete the file. + * + * If an optional bucket brigade is passed, the lock will only be + * removed if the bucket brigade contains an EOS bucket. + */ +CACHE_DECLARE(apr_status_t) ap_cache_remove_lock(cache_server_conf *conf, + request_rec *r, char *key, apr_bucket_brigade *bb); + +/** * Merge in cached headers into the response * @param h cache_handle_t * @param r request_rec @@ -330,8 +380,8 @@ apr_status_t cache_recall_entity_body(cache_handle_t *h, apr_pool_t *p, apr_buck #define CACHE_DECLARE_DATA __declspec(dllimport) #endif -APR_DECLARE_OPTIONAL_FN(apr_status_t, - ap_cache_generate_key, +APR_DECLARE_OPTIONAL_FN(apr_status_t, + ap_cache_generate_key, (request_rec *r, apr_pool_t*p, char**key )); |