Operational Data Subscription API

Functions
int	sr_oper_get_subscribe (sr_session_ctx_t *session, const char *module_name, const char *path, sr_oper_get_items_cb callback, void *private_data, sr_subscr_options_t opts, sr_subscription_ctx_t **subscription)
	Register for providing operational data at the given path. More...
int	sr_oper_poll_subscribe (sr_session_ctx_t *session, const char *module_name, const char *path, uint32_t valid_ms, sr_subscr_options_t opts, sr_subscription_ctx_t **subscription)
	Start periodic retrieval and caching of operational data at the given path. More...
typedef int(*	sr_oper_get_items_cb )(sr_session_ctx_t *session, uint32_t sub_id, const char *module_name, const char *path, const char *request_xpath, uint32_t request_id, struct lyd_node **parent, void *private_data)
	Callback to be called when operational data at the selected xpath are requested. Data are represented as libyang subtrees. More...

Detailed Description

Typedef Documentation

typedef int(* sr_oper_get_items_cb)(sr_session_ctx_t *session, uint32_t sub_id, const char *module_name, const char *path, const char *request_xpath, uint32_t request_id, struct lyd_node **parent, void *private_data)

Callback to be called when operational data at the selected xpath are requested. Data are represented as libyang subtrees.

When the callback is called, the data parent is provided. Any parent children (selected by path) are removed and should be provided by the callback instead, if they exist. Callback handler can provide any data matching the path but in case there are other nested subscriptions, they will be called after this one (and when they are called, their parent children will again be removed which can result in nodes provided by the original callback being lost).

Note

Callback must not modify the same module operational subscriptions, it would result in a deadlock.

Parameters

[in]	session	Implicit session (do not stop) with information about the event originator session IDs.
[in]	sub_id	Subscription ID.
[in]	module_name	Name of the affected module.
[in]	path	Path identifying the subtree that is supposed to be provided, same as the one used for the subscription.
[in]	request_xpath	XPath as requested by a client. Can be NULL.
[in]	request_id	Request ID unique for the specific module_name.
[in,out]	parent	Pointer to an existing parent of the requested nodes. Is NULL for top-level nodes. Caller is supposed to append the requested nodes to this data subtree and return either the original parent or a top-level node.
[in]	private_data	Private context opaque to sysrepo, as passed to sr_oper_get_subscribe call.

Returns

User error code (SR_ERR_OK on success).

Definition at line 683 of file sysrepo_types.h.

Function Documentation

int sr_oper_get_subscribe	(	sr_session_ctx_t *	session,
		const char *	module_name,
		const char *	path,
		sr_oper_get_items_cb	callback,
		void *	private_data,
		sr_subscr_options_t	opts,
		sr_subscription_ctx_t **	subscription
	)

Register for providing operational data at the given path.

Usual behaviour is only ONE subscription for ONE XPath. When subscribing to the same XPath that was used in some previous subscription, SR_SUBSCR_OPER_MERGE flag has to be used. Every such subscription (for the same XPath) has its internal priority based on the order in which it was subscribed. This priority influences merging the operational data from multiple subscriptions with the same XPath. Operational data returned by later subscriptions overwrite the same data from any previous subscriptions. When retrieving data all subscription callbacks with the same XPath are called simultaneously (to actually achieve this, subscription should be different for each subscription so that there are separate threads listening for each of the events, otherwise the thread will call the callback sequentially).

Required WRITE access.

Note

Be aware of some specific threading limitations.

Parameters

[in]	session	Session (not DS-specific) to use.
[in]	module_name	Name of the affected module.
[in]	path	Path identifying the subtree (not strictly required, all list/leaf-list instances are also valid, for example) which the provider is able to provide. Predicates can be used to provide only specific instances of nodes. Before calling this callback, any existing data matching this path are deleted (unless modified by opts).
[in]	callback	Callback to be called when the operational data for the given xpath are requested.
[in]	private_data	Private context passed to the callback function, opaque to sysrepo.
[in]	opts	Options overriding default behavior of the subscription, it is supposed to be a bitwise OR-ed value of any sr_subscr_flag_t flags.
[in,out]	subscription	Subscription context, zeroed for first subscription, freed by sr_unsubscribe.

Returns

Error code (SR_ERR_OK on success).

int sr_oper_poll_subscribe	(	sr_session_ctx_t *	session,
		const char *	module_name,
		const char *	path,
		uint32_t	valid_ms,
		sr_subscr_options_t	opts,
		sr_subscription_ctx_t **	subscription
	)

Start periodic retrieval and caching of operational data at the given path.

The operational data are cached in the connection of session. When any session created on this connection requires data of the cached operational get subscription at path, the callback is not called and the cached data are used instead. Additionally, if opts include SR_SUBSCR_OPER_POLL_DIFF, any changes detected on cache data refresh are reported to corresponding subscribers. For an operational get subscription, there can only be a single operational poll subscription with this flag. The first cache update is performed directly by this function.

Required READ access.

Note

Be aware of some specific threading limitations. Especially note that you cannot have an operational poll subscription in the same subscription structure as the operational get subscription being cached because a dead-lock would occur on cache update.

Parameters

[in]	session	Session (not DS-specific) to use.
[in]	module_name	Name of the affected module.
[in]	path	Path matching the operational get subscription(s) to poll.
[in]	valid_ms	Time the retrieved data are stored in cache until being considered invalid.
[in]	opts	Options overriding default behavior of the subscription, it is supposed to be a bitwise OR-ed value of any sr_subscr_flag_t flags.
[in,out]	subscription	Subscription context, zeroed for first subscription, freed by sr_unsubscribe.

Returns

Error code (SR_ERR_OK on success).