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json: Use reference counting in JSON objects

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After profiling OVSDB insert performance it was found
that some significant portion of its time OVSDB is
calling the function json_clone.

Also, the current usages of json_clone never modify the json,
just keeps it to prevent it to be freed.

With that in mind the struct json, json_create, json_clone
and json_destroy were modified to keep a count of how many
references of the json struct are left. Only when that count
reaches zero the json struct is freed.

The old "json_clone" function was renamed as "json_deep_clone".

Some examples of the performance difference:

In these tests a test table with 4 columns (string, string,
bool, integer) was used. All the tests used "commit block".

*** 50 process each inserting 1000 rows ***

Master OVS
Test Duration                   131 seconds
Average Inserts Per second      746.2687 inserts/s
Average Insert Duration         134.1382 ms
Minimal Insert Duration           0.166202 ms
Maximum Insert Duration	        489.8593 ms

JSON GC Patch
Test Duration                   86 seconds
Average Inserts Per second    1176 inserts/s
Average Insert Duration         82.26761 ms
Minimal Insert Duration          0.165448 ms
Maximum Insert Duration        751.2111 ms

*** 5 process each inserting 10000 rows ***

Master OVS
Test Duration                      8 seconds
Average Inserts Per second      7142.857 inserts/s
Average Insert Duration            0.656431 ms
Minimal Insert Duration            0.125197 ms
Maximum Insert Duration           11.93203 ms

JSON GC Patch
Test Duration                      7 seconds
Average Inserts Per second      8333.333 inserts/s
Average Insert Duration            0.55688 ms
Minimal Insert Duration            0.143233 ms
Maximum Insert Duration           26.26319 ms

Signed-off-by: Esteban Rodriguez Betancourt <estebarb@hpe.com>
Signed-off-by: Ben Pfaff <blp@ovn.org>
This commit is contained in:
Rodriguez Betancourt, Esteban
2016-10-04 19:31:48 +00:00
committed by Ben Pfaff
parent 2e3cf773ea
commit 9854d473ad
2 changed files with 18 additions and 2 deletions
Download Patch File Download Diff File Expand all files Collapse all files

2
include/openvswitch/json.h
View File

@@ -63,6 +63,7 @@ struct json_array {
/* A JSON value. */
struct json {
enum json_type type;
size_t count;
union {
struct shash *object; /* Contains "struct json *"s. */
struct json_array array;
@@ -99,6 +100,7 @@ bool json_boolean(const struct json *);
double json_real(const struct json *);
int64_t json_integer(const struct json *);
struct json *json_deep_clone(const struct json *);
struct json *json_clone(const struct json *);
void json_destroy(struct json *);

18
lib/json.c
View File

@@ -333,7 +333,7 @@ static void json_destroy_array(struct json_array *array);
void
json_destroy(struct json *json)
{
if (json) {
if (json && !--json->count) {
switch (json->type) {
case JSON_OBJECT:
json_destroy_object(json->u.object);
@@ -392,7 +392,7 @@ static struct json *json_clone_array(const struct json_array *array);
/* Returns a deep copy of 'json'. */
struct json *
json_clone(const struct json *json)
json_deep_clone(const struct json *json)
{
switch (json->type) {
case JSON_OBJECT:
@@ -421,6 +421,15 @@ json_clone(const struct json *json)
}
}
/* Returns 'json', with the reference count incremented. */
struct json *
json_clone(const struct json *json_)
{
struct json *json = CONST_CAST(struct json *, json_);
json->count++;
return json;
}
static struct json *
json_clone_object(const struct shash *object)
{
@@ -547,6 +556,10 @@ json_equal_array(const struct json_array *a, const struct json_array *b)
bool
json_equal(const struct json *a, const struct json *b)
{
if (a == b) {
return true;
}
if (a->type != b->type) {
return false;
}
@@ -1405,6 +1418,7 @@ json_create(enum json_type type)
{
struct json *json = xmalloc(sizeof *json);
json->type = type;
json->count = 1;
return json;
}