Although multiple jsonrpc monitor can share the same ovsdb monitor, each
change still needs to transalted into json object from scratch. This
can be wastful is mutiple jsonrpc monitors are interested in the
same changes.
Json chche impoves this by keeping an copy of json object generated
for transaction X to current transaction. When jsonrpc is interested
in a change, the cache is lookup first, if an json object is found,
a copy of it is handed back, skipping the regeneration process.
Any commit to the monitor will empty the cache. since none of them
will be useful anymore.
Signed-off-by: Andy Zhou <az...@nicira.com>
---
ovsdb/ovsdb-monitor.c | 100 ++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 100 insertions(+)
diff --git a/ovsdb/ovsdb-monitor.c b/ovsdb/ovsdb-monitor.c
index 210b33c..2fda283 100644
--- a/ovsdb/ovsdb-monitor.c
+++ b/ovsdb/ovsdb-monitor.c
@@ -41,6 +41,7 @@ VLOG_DEFINE_THIS_MODULE(ovsdb_monitor);
static const struct ovsdb_replica_class ovsdb_jsonrpc_replica_class;
static struct hmap ovsdb_monitors;
+static struct hmap json_cache__;
/* Backend monitor.
*
@@ -58,6 +59,15 @@ struct ovsdb_monitor {
struct hmap_node hmap_node; /* Elements within ovsdb_monitors. */
};
+/* A json object of updates between 'from_txn' and 'dbmon->n_transactions'
+ * inclusive. */
+struct ovsdb_monitor_json_cache_node {
+ struct hmap_node hmap_node; /* Elements in json cache. */
+ const struct ovsdb_monitor *dbmon;
+ uint64_t from_txn;
+ struct json *json; /* Null, or a cloned of json */
+};
+
struct jsonrpc_monitor_node {
struct ovsdb_jsonrpc_monitor *jsonrpc_monitor;
struct ovs_list node;
@@ -122,6 +132,84 @@ static void ovsdb_monitor_changes_destroy_rows(
static void ovsdb_monitor_table_track_changes(struct ovsdb_monitor_table *mt,
uint64_t unflushed);
+static struct hmap *
+get_json_cache(void)
+{
+ static bool init__ = false;
+
+ if (!init__) {
+ hmap_init(&json_cache__);
+ init__ = true;
+ }
+ return &json_cache__;
+}
+
+static uint32_t
+ovsdb_monitor_json_cache_hash(const struct ovsdb_monitor *dbmon,
+ uint64_t from_txn)
+{
+ uint32_t hash;
+
+ hash = hash_uint64(from_txn);
+ hash = hash_pointer(dbmon, hash);
+ return hash;
+}
+
+static struct ovsdb_monitor_json_cache_node *
+ovsdb_monitor_json_cache_search(const struct ovsdb_monitor *dbmon,
+ uint64_t from_txn)
+{
+ struct ovsdb_monitor_json_cache_node *node;
+ struct hmap *json_cache = get_json_cache();
+ uint32_t hash;
+
+ hash = ovsdb_monitor_json_cache_hash(dbmon, from_txn);
+
+ HMAP_FOR_EACH_WITH_HASH(node, hmap_node, hash, json_cache) {
+ if ((node->from_txn == from_txn) && (node->dbmon == dbmon)) {
+ return node;
+ }
+ }
+
+ return NULL;
+}
+
+static void
+ovsdb_monitor_json_cache_insert(const struct ovsdb_monitor *dbmon,
+ uint64_t from_txn, struct json *json)
+{
+ struct ovsdb_monitor_json_cache_node *node;
+ struct hmap *json_cache = get_json_cache();
+ uint32_t hash;
+
+ hash = ovsdb_monitor_json_cache_hash(dbmon, from_txn);
+
+ node = xmalloc(sizeof *node);
+
+ node->from_txn = from_txn;
+ node->json = json ? json_clone(json) : NULL;
+ node->dbmon = dbmon;
+
+ hmap_insert(json_cache, &node->hmap_node, hash);
+}
+
+static void
+ovsdb_monitor_json_cache_flush(struct ovsdb_monitor *dbmon)
+{
+ struct ovsdb_monitor_json_cache_node *node, *next;
+ struct hmap *json_cache = get_json_cache();
+
+ HMAP_FOR_EACH_SAFE(node, next, hmap_node, json_cache) {
+ if (node->dbmon == dbmon) {
+ hmap_remove(json_cache, &node->hmap_node);
+ if (node->json) {
+ json_destroy(node->json);
+ }
+ free(node);
+ }
+ }
+}
+
static int
compare_ovsdb_monitor_column(const void *a_, const void *b_)
{
@@ -499,6 +587,7 @@ struct json *
ovsdb_monitor_compose_update(const struct ovsdb_monitor *dbmon,
bool initial, uint64_t *unflushed)
{
+ struct ovsdb_monitor_json_cache_node *cache_node;
struct shash_node *node;
unsigned long int *changed;
struct json *json;
@@ -508,6 +597,12 @@ ovsdb_monitor_compose_update(const struct ovsdb_monitor
*dbmon,
from_txn = initial ? 0 : *unflushed;
*unflushed = dbmon->n_transactions + 1;
+ /* Return cached json if one has been created already */
+ cache_node = ovsdb_monitor_json_cache_search(dbmon, from_txn);
+ if (cache_node) {
+ return cache_node->json ? json_clone(cache_node->json) : NULL;
+ }
+
max_columns = 0;
SHASH_FOR_EACH (node, &dbmon->tables) {
struct ovsdb_monitor_table *mt = node->data;
@@ -555,6 +650,8 @@ ovsdb_monitor_compose_update(const struct ovsdb_monitor
*dbmon,
}
free(changed);
+
+ ovsdb_monitor_json_cache_insert(dbmon, from_txn, json);
return json;
}
@@ -871,6 +968,8 @@ ovsdb_monitor_destroy(struct ovsdb_monitor *dbmon)
hmap_remove(&ovsdb_monitors, &dbmon->hmap_node);
}
+ ovsdb_monitor_json_cache_flush(dbmon);
+
SHASH_FOR_EACH (node, &dbmon->tables) {
struct ovsdb_monitor_table *mt = node->data;
struct ovsdb_monitor_changes *changes, *next;
@@ -896,6 +995,7 @@ ovsdb_monitor_commit(struct ovsdb_replica *replica,
struct ovsdb_monitor *m = ovsdb_monitor_cast(replica);
struct ovsdb_monitor_aux aux;
+ ovsdb_monitor_json_cache_flush(m);
ovsdb_monitor_init_aux(&aux, m);
ovsdb_txn_for_each_change(txn, ovsdb_monitor_change_cb, &aux);
m->n_transactions++;
--
1.9.1
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