[PATCH BlueZ 07/15] shared/gatt-db: Introduce Database Hash

[Luiz Augusto von Dentz <luiz.dentz@gmail.com>]

From: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>

This introduces a database hash which is generate whenever the database
changes.
---
 src/shared/gatt-db.c | 36 ++++++++++++++++++++++++++++++++++++
 src/shared/gatt-db.h |  1 +
 2 files changed, 37 insertions(+)

diff --git a/src/shared/gatt-db.c b/src/shared/gatt-db.c
index d28301ac4..d97dca124 100644
--- a/src/shared/gatt-db.c
+++ b/src/shared/gatt-db.c
@@ -43,6 +43,7 @@
 #define MAX_CHAR_DECL_VALUE_LEN 19
 #define MAX_INCLUDED_VALUE_LEN 6
 #define ATTRIBUTE_TIMEOUT 5000
+#define HASH_UPDATE_TIMEOUT 100
 
 static const bt_uuid_t primary_service_uuid = { .type = BT_UUID16,
 					.value.u16 = GATT_PRIM_SVC_UUID };
@@ -57,6 +58,8 @@ static const bt_uuid_t ext_desc_uuid = { .type = BT_UUID16,
 
 struct gatt_db {
 	int ref_count;
+	uint8_t hash[16];
+	unsigned int hash_id;
 	uint16_t next_handle;
 	struct queue *services;
 
@@ -263,6 +266,15 @@ static void handle_notify(void *data, void *user_data)
 		notify->service_removed(notify_data->attr, notify->user_data);
 }
 
+static bool db_hash_update(void *user_data)
+{
+	struct gatt_db *db = user_data;
+
+	db->hash_id = 0;
+
+	return false;
+}
+
 static void notify_service_changed(struct gatt_db *db,
 						struct gatt_db_service *service,
 						bool added)
@@ -279,6 +291,11 @@ static void notify_service_changed(struct gatt_db *db,
 
 	queue_foreach(db->notify_list, handle_notify, &data);
 
+	/* Tigger hash update */
+	if (!db->hash_id)
+		db->hash_id = timeout_add(HASH_UPDATE_TIMEOUT, db_hash_update,
+								db, NULL);
+
 	gatt_db_unref(db);
 }
 
@@ -309,6 +326,9 @@ static void gatt_db_destroy(struct gatt_db *db)
 	queue_destroy(db->notify_list, notify_destroy);
 	db->notify_list = NULL;
 
+	if (db->hash_id)
+		timeout_remove(db->hash_id);
+
 	queue_destroy(db->services, gatt_db_service_destroy);
 	free(db);
 }
@@ -482,6 +502,22 @@ done:
 	return true;
 }
 
+uint8_t *gatt_db_get_hash(struct gatt_db *db)
+{
+	uint8_t hash[16] = {};
+
+	if (!db)
+		return NULL;
+
+	/* Generate hash if if has not been generated yet */
+	if (db->hash_id || !memcmp(db->hash, hash, 16)) {
+		timeout_remove(db->hash_id);
+		db_hash_update(db);
+	}
+
+	return db->hash;
+}
+
 static struct gatt_db_service *find_insert_loc(struct gatt_db *db,
 						uint16_t start, uint16_t end,
 						struct gatt_db_service **after)
diff --git a/src/shared/gatt-db.h b/src/shared/gatt-db.h
index e2ac645f3..f3ab803d1 100644
--- a/src/shared/gatt-db.h
+++ b/src/shared/gatt-db.h
@@ -41,6 +41,7 @@ bool gatt_db_remove_service(struct gatt_db *db,
 bool gatt_db_clear(struct gatt_db *db);
 bool gatt_db_clear_range(struct gatt_db *db, uint16_t start_handle,
 							uint16_t end_handle);
+uint8_t *gatt_db_get_hash(struct gatt_db *db);
 
 struct gatt_db_attribute *gatt_db_insert_service(struct gatt_db *db,
 							uint16_t handle,
-- 
2.17.2