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This patch adds notify.md file. Signed-off-by: Piotr Pelplinski <piotr.pelplinski@intel.com> Change-Id: I65555d3e2cc8d8d616f56ca40e95d558e2654fb7 Reviewed-on: https://review.gerrithub.io/c/spdk/spdk/+/435087 Tested-by: SPDK CI Jenkins <sys_sgci@intel.com> Reviewed-by: Ben Walker <benjamin.walker@intel.com> Reviewed-by: Jim Harris <james.r.harris@intel.com>
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Notify library
The notify library implements an event bus, allowing users to register, generate, and listen for events. For example, the bdev library may register a new event type for bdev creation. Any time a bdev is created, it "sends" the event. Consumers of that event may periodically poll for new events to retrieve them. The event bus is implemented as a circular ring of fixed size. If event consumers do not poll frequently enough, events may be lost. All events are identified by a monotonically increasing integer, so missing events may be detected, although not recovered.
Register event types
During initialization the sender library should register its own event types using
spdk_notify_type_register(const char *type). Parameter 'type' is the name of
notification type.
Get info about events
A consumer can get information about the available event types during runtime using
spdk_notify_get_types, which iterates over registered notification types and
calls a callback on each of them, so that user can produce detailed information
about notification.
Get new events
A consumer can get events by calling function spdk_notify_get_events.
The caller should specify last received event and the maximum number of invocations.
There might be multiple consumers of each event. The event bus is implemented as a
circular buffer, so older events may be overwritten by newer ones.
Send events
When an event occurs, a library can invoke spdk_notify_send with two strings.
One containing the type of the event, like "spdk_bdev_register", second with context,
for example "Nvme0n1"