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Split caching out from the stasis_caching_topic.

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In working with res_stasis, I discovered a significant limitation to
the current structure of stasis_caching_topics: you cannot subscribe
to cache updates for a single channel/bridge/endpoint/etc.

To address this, this patch splits the cache away from the
stasis_caching_topic, making it a first class object. The stasis_cache
object is shared amongst individual stasis_caching_topics that are
created per channel/endpoint/etc. These are still forwarded to global
whatever_all_cached topics, so their use from most of the code does
not change.

In making these changes, I noticed that we frequently used a similar
pattern for bridges, endpoints and channels:

     single_topic  ---------------->  all_topic
           ^
           |
     single_topic_cached  ----+---->  all_topic_cached
                              |
                              +---->  cache

This pattern was extracted as the 'Stasis Caching Pattern', defined in
stasis_caching_pattern.h. This avoids a lot of duplicate code between
the different domain objects.

Since the cache is now disassociated from its upstream caching topics,
this also necessitated a change to how the 'guaranteed' flag worked
for retrieving from a cache. The code for handling the caching
guarantee was extracted into a 'stasis_topic_wait' function, which
works for any stasis_topic.

(closes issue ASTERISK-22002)
Review: https://reviewboard.asterisk.org/r/2672/


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@395954 65c4cc65-6c06-0410-ace0-fbb531ad65f3
This commit is contained in:
David M. Lee
2013-08-01 13:49:34 +00:00
parent 5c13969469
commit e1b959ccbb
54 changed files with 1179 additions and 448 deletions
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177
main/stasis_cache.c
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@@ -44,15 +44,18 @@ ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
#endif
/*! \internal */
struct stasis_caching_topic {
struct ao2_container *cache;
struct stasis_topic *topic;
struct stasis_topic *original_topic;
struct stasis_subscription *sub;
struct stasis_cache {
struct ao2_container *entries;
snapshot_get_id id_fn;
};
static struct stasis_message_type *cache_guarantee_type(void);
/*! \internal */
struct stasis_caching_topic {
struct stasis_cache *cache;
struct stasis_topic *topic;
struct stasis_topic *original_topic;
struct stasis_subscription *sub;
};
static void stasis_caching_topic_dtor(void *obj) {
struct stasis_caching_topic *caching_topic = obj;
@@ -136,7 +139,8 @@ static struct cache_entry *cache_entry_create(struct stasis_message_type *type,
ast_assert(type != NULL);
ast_assert(id != NULL);
entry = ao2_alloc(sizeof(*entry), cache_entry_dtor);
entry = ao2_alloc_options(sizeof(*entry), cache_entry_dtor,
AO2_ALLOC_OPT_LOCK_NOLOCK);
if (!entry) {
return NULL;
}
@@ -183,28 +187,62 @@ static int cache_entry_cmp(void *obj, void *arg, int flags)
return 0;
}
static struct stasis_message *cache_put(struct stasis_caching_topic *caching_topic, struct stasis_message_type *type, const char *id, struct stasis_message *new_snapshot)
static void cache_dtor(void *obj)
{
struct stasis_cache *cache = obj;
ao2_cleanup(cache->entries);
cache->entries = NULL;
}
struct stasis_cache *stasis_cache_create(snapshot_get_id id_fn)
{
RAII_VAR(struct stasis_cache *, cache, NULL, ao2_cleanup);
cache = ao2_alloc_options(sizeof(*cache), cache_dtor,
AO2_ALLOC_OPT_LOCK_NOLOCK);
if (!cache) {
return NULL;
}
cache->entries = ao2_container_alloc(NUM_CACHE_BUCKETS, cache_entry_hash,
cache_entry_cmp);
if (!cache->entries) {
return NULL;
}
cache->id_fn = id_fn;
ao2_ref(cache, +1);
return cache;
}
static struct stasis_message *cache_put(struct stasis_cache *cache,
struct stasis_message_type *type, const char *id,
struct stasis_message *new_snapshot)
{
RAII_VAR(struct cache_entry *, new_entry, NULL, ao2_cleanup);
RAII_VAR(struct cache_entry *, cached_entry, NULL, ao2_cleanup);
struct stasis_message *old_snapshot = NULL;
ast_assert(caching_topic->cache != NULL);
ast_assert(cache->entries != NULL);
ast_assert(new_snapshot == NULL ||
type == stasis_message_type(new_snapshot));
new_entry = cache_entry_create(type, id, new_snapshot);
if (new_snapshot == NULL) {
/* Remove entry from cache */
cached_entry = ao2_find(caching_topic->cache, new_entry, OBJ_POINTER | OBJ_UNLINK);
cached_entry = ao2_find(cache->entries, new_entry, OBJ_POINTER | OBJ_UNLINK);
if (cached_entry) {
old_snapshot = cached_entry->snapshot;
cached_entry->snapshot = NULL;
}
} else {
/* Insert/update cache */
SCOPED_AO2LOCK(lock, caching_topic->cache);
SCOPED_AO2LOCK(lock, cache->entries);
cached_entry = ao2_find(caching_topic->cache, new_entry, OBJ_POINTER | OBJ_NOLOCK);
cached_entry = ao2_find(cache->entries, new_entry, OBJ_POINTER | OBJ_NOLOCK);
if (cached_entry) {
/* Update cache. Because objects are moving, no need to update refcounts. */
old_snapshot = cached_entry->snapshot;
@@ -212,7 +250,7 @@ static struct stasis_message *cache_put(struct stasis_caching_topic *caching_top
new_entry->snapshot = NULL;
} else {
/* Insert into the cache */
ao2_link_flags(caching_topic->cache, new_entry, OBJ_NOLOCK);
ao2_link_flags(cache->entries, new_entry, OBJ_NOLOCK);
}
}
@@ -220,68 +258,19 @@ static struct stasis_message *cache_put(struct stasis_caching_topic *caching_top
return old_snapshot;
}
/*! \internal */
struct caching_guarantee {
ast_mutex_t lock;
ast_cond_t cond;
unsigned int done:1;
};
static void caching_guarantee_dtor(void *obj)
{
struct caching_guarantee *guarantee = obj;
ast_assert(guarantee->done == 1);
ast_mutex_destroy(&guarantee->lock);
ast_cond_destroy(&guarantee->cond);
}
static struct stasis_message *caching_guarantee_create(void)
{
RAII_VAR(struct caching_guarantee *, guarantee, NULL, ao2_cleanup);
RAII_VAR(struct stasis_message *, msg, NULL, ao2_cleanup);
if (!(guarantee = ao2_alloc(sizeof(*guarantee), caching_guarantee_dtor))) {
return NULL;
}
ast_mutex_init(&guarantee->lock);
ast_cond_init(&guarantee->cond, NULL);
if (!(msg = stasis_message_create(cache_guarantee_type(), guarantee))) {
return NULL;
}
ao2_ref(msg, +1);
return msg;
}
struct stasis_message *stasis_cache_get_extended(struct stasis_caching_topic *caching_topic, struct stasis_message_type *type, const char *id, unsigned int guaranteed)
struct stasis_message *stasis_cache_get(struct stasis_cache *cache, struct stasis_message_type *type, const char *id)
{
RAII_VAR(struct cache_entry *, search_entry, NULL, ao2_cleanup);
RAII_VAR(struct cache_entry *, cached_entry, NULL, ao2_cleanup);
ast_assert(caching_topic->cache != NULL);
if (guaranteed) {
RAII_VAR(struct stasis_message *, msg, caching_guarantee_create(), ao2_cleanup);
struct caching_guarantee *guarantee = stasis_message_data(msg);
ast_mutex_lock(&guarantee->lock);
stasis_publish(caching_topic->original_topic, msg);
while (!guarantee->done) {
ast_cond_wait(&guarantee->cond, &guarantee->lock);
}
ast_mutex_unlock(&guarantee->lock);
}
ast_assert(cache->entries != NULL);
search_entry = cache_entry_create(type, id, NULL);
if (search_entry == NULL) {
return NULL;
}
cached_entry = ao2_find(caching_topic->cache, search_entry, OBJ_POINTER);
cached_entry = ao2_find(cache->entries, search_entry, OBJ_POINTER);
if (cached_entry == NULL) {
return NULL;
}
@@ -308,25 +297,25 @@ static int cache_dump_cb(void *obj, void *arg, int flags)
return 0;
}
struct ao2_container *stasis_cache_dump(struct stasis_caching_topic *caching_topic, struct stasis_message_type *type)
struct ao2_container *stasis_cache_dump(struct stasis_cache *cache, struct stasis_message_type *type)
{
struct cache_dump_data cache_dump;
ast_assert(caching_topic->cache != NULL);
ast_assert(cache->entries != NULL);
cache_dump.type = type;
cache_dump.cached = ao2_container_alloc(1, NULL, NULL);
cache_dump.cached = ao2_container_alloc_options(
AO2_ALLOC_OPT_LOCK_NOLOCK, 1, NULL, NULL);
if (!cache_dump.cached) {
return NULL;
}
ao2_callback(caching_topic->cache, OBJ_MULTIPLE | OBJ_NODATA, cache_dump_cb, &cache_dump);
ao2_callback(cache->entries, OBJ_MULTIPLE | OBJ_NODATA, cache_dump_cb, &cache_dump);
return cache_dump.cached;
}
STASIS_MESSAGE_TYPE_DEFN(stasis_cache_clear_type);
STASIS_MESSAGE_TYPE_DEFN(stasis_cache_update_type);
STASIS_MESSAGE_TYPE_DEFN(cache_guarantee_type);
struct stasis_message *stasis_cache_clear_create(struct stasis_message *id_message)
{
@@ -362,7 +351,8 @@ static struct stasis_message *update_create(struct stasis_topic *topic, struct s
ast_assert(topic != NULL);
ast_assert(old_snapshot != NULL || new_snapshot != NULL);
update = ao2_alloc(sizeof(*update), stasis_cache_update_dtor);
update = ao2_alloc_options(sizeof(*update), stasis_cache_update_dtor,
AO2_ALLOC_OPT_LOCK_NOLOCK);
if (!update) {
return NULL;
}
@@ -393,7 +383,8 @@ static struct stasis_message *update_create(struct stasis_topic *topic, struct s
return msg;
}
static void caching_topic_exec(void *data, struct stasis_subscription *sub, struct stasis_topic *topic, struct stasis_message *message)
static void caching_topic_exec(void *data, struct stasis_subscription *sub,
struct stasis_topic *topic, struct stasis_message *message)
{
RAII_VAR(struct stasis_caching_topic *, caching_topic_needs_unref, NULL, ao2_cleanup);
struct stasis_caching_topic *caching_topic = data;
@@ -401,36 +392,25 @@ static void caching_topic_exec(void *data, struct stasis_subscription *sub, stru
ast_assert(caching_topic != NULL);
ast_assert(caching_topic->topic != NULL);
ast_assert(caching_topic->id_fn != NULL);
ast_assert(caching_topic->cache != NULL);
ast_assert(caching_topic->cache->id_fn != NULL);
if (stasis_subscription_final_message(sub, message)) {
caching_topic_needs_unref = caching_topic;
}
/* Handle cache guarantee event */
if (cache_guarantee_type() == stasis_message_type(message)) {
struct caching_guarantee *guarantee = stasis_message_data(message);
ast_mutex_lock(&guarantee->lock);
guarantee->done = 1;
ast_cond_signal(&guarantee->cond);
ast_mutex_unlock(&guarantee->lock);
return;
}
/* Handle cache clear event */
if (stasis_cache_clear_type() == stasis_message_type(message)) {
RAII_VAR(struct stasis_message *, old_snapshot, NULL, ao2_cleanup);
RAII_VAR(struct stasis_message *, update, NULL, ao2_cleanup);
struct stasis_message *clear_msg = stasis_message_data(message);
const char *clear_id = caching_topic->id_fn(clear_msg);
const char *clear_id = caching_topic->cache->id_fn(clear_msg);
struct stasis_message_type *clear_type = stasis_message_type(clear_msg);
ast_assert(clear_type != NULL);
if (clear_id) {
old_snapshot = cache_put(caching_topic, clear_type, clear_id, NULL);
old_snapshot = cache_put(caching_topic->cache, clear_type, clear_id, NULL);
if (old_snapshot) {
update = update_create(topic, old_snapshot, NULL);
stasis_publish(caching_topic->topic, update);
@@ -444,7 +424,7 @@ static void caching_topic_exec(void *data, struct stasis_subscription *sub, stru
}
}
id = caching_topic->id_fn(message);
id = caching_topic->cache->id_fn(message);
if (id == NULL) {
/* Object isn't cached; forward */
stasis_forward_message(caching_topic->topic, topic, message);
@@ -453,7 +433,7 @@ static void caching_topic_exec(void *data, struct stasis_subscription *sub, stru
RAII_VAR(struct stasis_message *, old_snapshot, NULL, ao2_cleanup);
RAII_VAR(struct stasis_message *, update, NULL, ao2_cleanup);
old_snapshot = cache_put(caching_topic, stasis_message_type(message), id, message);
old_snapshot = cache_put(caching_topic->cache, stasis_message_type(message), id, message);
update = update_create(topic, old_snapshot, message);
if (update == NULL) {
@@ -464,7 +444,7 @@ static void caching_topic_exec(void *data, struct stasis_subscription *sub, stru
}
}
struct stasis_caching_topic *stasis_caching_topic_create(struct stasis_topic *original_topic, snapshot_get_id id_fn)
struct stasis_caching_topic *stasis_caching_topic_create(struct stasis_topic *original_topic, struct stasis_cache *cache)
{
RAII_VAR(struct stasis_caching_topic *, caching_topic, NULL, ao2_cleanup);
struct stasis_subscription *sub;
@@ -476,23 +456,19 @@ struct stasis_caching_topic *stasis_caching_topic_create(struct stasis_topic *or
return NULL;
}
caching_topic = ao2_alloc(sizeof(*caching_topic), stasis_caching_topic_dtor);
caching_topic = ao2_alloc_options(sizeof(*caching_topic),
stasis_caching_topic_dtor, AO2_ALLOC_OPT_LOCK_NOLOCK);
if (caching_topic == NULL) {
return NULL;
}
caching_topic->cache = ao2_container_alloc(NUM_CACHE_BUCKETS, cache_entry_hash, cache_entry_cmp);
if (!caching_topic->cache) {
ast_log(LOG_ERROR, "Stasis cache allocation failed\n");
return NULL;
}
caching_topic->topic = stasis_topic_create(new_name);
if (caching_topic->topic == NULL) {
return NULL;
}
caching_topic->id_fn = id_fn;
ao2_ref(cache, +1);
caching_topic->cache = cache;
sub = internal_stasis_subscribe(original_topic, caching_topic_exec, caching_topic, 0);
if (sub == NULL) {
@@ -514,7 +490,6 @@ static void stasis_cache_cleanup(void)
{
STASIS_MESSAGE_TYPE_CLEANUP(stasis_cache_clear_type);
STASIS_MESSAGE_TYPE_CLEANUP(stasis_cache_update_type);
STASIS_MESSAGE_TYPE_CLEANUP(cache_guarantee_type);
}
int stasis_cache_init(void)
@@ -529,10 +504,6 @@ int stasis_cache_init(void)
return -1;
}
if (STASIS_MESSAGE_TYPE_INIT(cache_guarantee_type) != 0) {
return -1;
}
return 0;
}