[ovs-dev] [PATCH 19/19] ovsdb-monitor: add json cache
Andy Zhou
azhou at nicira.com
Fri Apr 10 00:11:38 UTC 2015
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 <azhou at nicira.com>
---
v1->v2: Each monitor now has its own json cache. Remove the global
json cache.
Some refatoring to make to code easier to follow.
---
ovsdb/jsonrpc-server.c | 2 +-
ovsdb/monitor.c | 118 ++++++++++++++++++++++++++++++++++++++++++-------
ovsdb/monitor.h | 2 +-
3 files changed, 104 insertions(+), 18 deletions(-)
diff --git a/ovsdb/jsonrpc-server.c b/ovsdb/jsonrpc-server.c
index a622c59..e84149f 100644
--- a/ovsdb/jsonrpc-server.c
+++ b/ovsdb/jsonrpc-server.c
@@ -1294,7 +1294,7 @@ static struct json *
ovsdb_jsonrpc_monitor_compose_update(struct ovsdb_jsonrpc_monitor *m,
bool initial)
{
- return ovsdb_monitor_compose_update(m->dbmon, initial, &m->unflushed);
+ return ovsdb_monitor_get_update(m->dbmon, initial, &m->unflushed);
}
static bool
diff --git a/ovsdb/monitor.c b/ovsdb/monitor.c
index 49a5ca3..eac57d2 100644
--- a/ovsdb/monitor.c
+++ b/ovsdb/monitor.c
@@ -54,6 +54,15 @@ struct ovsdb_monitor {
struct ovsdb *db;
uint64_t n_transactions; /* Count number of committed transactions. */
struct hmap_node hmap_node; /* Elements within ovsdb_monitors. */
+ struct hmap json_cache; /* Contains "ovsdb_monitor_json_cache_node"s.*/
+};
+
+/* 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. */
+ uint64_t from_txn;
+ struct json *json; /* Null, or a cloned of json */
};
struct jsonrpc_monitor_node {
@@ -120,6 +129,52 @@ static void ovsdb_monitor_changes_destroy_rows(
static void ovsdb_monitor_table_track_changes(struct ovsdb_monitor_table *mt,
uint64_t unflushed);
+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;
+ uint32_t hash = hash_uint64(from_txn);
+
+ HMAP_FOR_EACH_WITH_HASH(node, hmap_node, hash, &dbmon->json_cache) {
+ if (node->from_txn == from_txn) {
+ return node;
+ }
+ }
+
+ return NULL;
+}
+
+static void
+ovsdb_monitor_json_cache_insert(struct ovsdb_monitor *dbmon,
+ uint64_t from_txn, struct json *json)
+{
+ struct ovsdb_monitor_json_cache_node *node;
+ uint32_t hash;
+
+ node = xmalloc(sizeof *node);
+
+ hash = hash_uint64(from_txn);
+ node->from_txn = from_txn;
+ node->json = json ? json_clone(json) : NULL;
+
+ hmap_insert(&dbmon->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;
+
+ HMAP_FOR_EACH_SAFE(node, next, hmap_node, &dbmon->json_cache) {
+ hmap_remove(&dbmon->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_)
{
@@ -259,6 +314,7 @@ ovsdb_monitor_create(struct ovsdb *db,
dbmon->n_transactions = 0;
shash_init(&dbmon->tables);
hmap_node_nullify(&dbmon->hmap_node);
+ hmap_init(&dbmon->json_cache);
ovsdb_monitor_add_jsonrpc_monitor(dbmon, jsonrpc_monitor);
return dbmon;
@@ -488,23 +544,16 @@ ovsdb_monitor_compose_row_update(
}
/* Constructs and returns JSON for a <table-updates> object (as described in
- * RFC 7047) for all the outstanding changes within 'monitor', and deletes all
- * the outstanding changes from 'monitor'. Returns NULL if no update needs to
- * be sent.
- *
- * The caller should specify 'initial' as true if the returned JSON is going to
- * be used as part of the initial reply to a "monitor" request, false if it is
- * going to be used as part of an "update" notification. */
-struct json *
-ovsdb_monitor_compose_update(const struct ovsdb_monitor *dbmon,
- bool initial, uint64_t *unflushed)
+ * RFC 7047) for all the outstanding changes within 'monitor', starting from
+ * 'transaction'. */
+static struct json*
+ovsdb_monitor_compose_update(struct ovsdb_monitor *dbmon,
+ bool initial, uint64_t transaction)
{
struct shash_node *node;
unsigned long int *changed;
struct json *json;
size_t max_columns;
- uint64_t prev_txn = *unflushed;
- uint64_t next_txn = dbmon->n_transactions + 1;
max_columns = 0;
SHASH_FOR_EACH (node, &dbmon->tables) {
@@ -521,9 +570,8 @@ ovsdb_monitor_compose_update(const struct ovsdb_monitor *dbmon,
struct ovsdb_monitor_changes *changes;
struct json *table_json = NULL;
- changes = ovsdb_monitor_table_find_changes(mt, prev_txn);
+ changes = ovsdb_monitor_table_find_changes(mt, transaction);
if (!changes) {
- ovsdb_monitor_table_track_changes(mt, next_txn);
continue;
}
@@ -551,13 +599,48 @@ ovsdb_monitor_compose_update(const struct ovsdb_monitor *dbmon,
json_object_put(table_json, uuid, row_json);
}
}
+ }
+ free(changed);
+
+ return json;
+}
+
+/* Returns JSON for a <table-updates> object (as described in RFC 7047)
+ * for all the outstanding changes within 'monitor' that starts from
+ * '*unflushed' transaction id.
+ *
+ * The caller should specify 'initial' as true if the returned JSON is going to
+ * be used as part of the initial reply to a "monitor" request, false if it is
+ * going to be used as part of an "update" notification. */
+struct json *
+ovsdb_monitor_get_update(struct ovsdb_monitor *dbmon,
+ bool initial, uint64_t *unflushed)
+{
+ struct ovsdb_monitor_json_cache_node *cache_node;
+ struct shash_node *node;
+ struct json *json;
+ uint64_t prev_txn = *unflushed;
+ uint64_t next_txn = dbmon->n_transactions + 1;
+
+ /* Return a clone of cached json if one exists. Otherwise,
+ * generate a new one and add it to the cache. */
+ cache_node = ovsdb_monitor_json_cache_search(dbmon, prev_txn);
+ if (cache_node) {
+ json = cache_node->json ? json_clone(cache_node->json) : NULL;
+ } else {
+ json = ovsdb_monitor_compose_update(dbmon, initial, prev_txn);
+ ovsdb_monitor_json_cache_insert(dbmon, prev_txn, json);
+ }
+
+ /* Maintain transaction id of 'changes'. */
+ SHASH_FOR_EACH (node, &dbmon->tables) {
+ struct ovsdb_monitor_table *mt = node->data;
ovsdb_monitor_table_untrack_changes(mt, prev_txn);
ovsdb_monitor_table_track_changes(mt, next_txn);
}
-
*unflushed = next_txn;
- free(changed);
+
return json;
}
@@ -847,6 +930,8 @@ 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;
@@ -872,6 +957,7 @@ 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++;
diff --git a/ovsdb/monitor.h b/ovsdb/monitor.h
index c952c6f..344f325 100644
--- a/ovsdb/monitor.h
+++ b/ovsdb/monitor.h
@@ -54,7 +54,7 @@ const char * OVS_WARN_UNUSED_RESULT
ovsdb_monitor_table_check_duplicates(struct ovsdb_monitor *,
const struct ovsdb_table *);
-struct json *ovsdb_monitor_compose_update(const struct ovsdb_monitor *dbmon,
+struct json *ovsdb_monitor_get_update(struct ovsdb_monitor *dbmon,
bool initial, uint64_t *unflushed_transaction);
void ovsdb_monitor_table_set_select(struct ovsdb_monitor *dbmon,
--
1.9.1
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