- A tevent_queue is used to queue up async requests that must be serialized.
The tevent operation functions
The following structure and registration functions are exclusively needed for people writing and pluggin a different event engine.
typedef void(* tevent_queue_trigger_fn_t) (struct tevent_req *req, void *private_data)
A callback trigger function run by the queue.
struct tevent_queue * tevent_queue_create (TALLOC_CTX *mem_ctx, const char *name)
Create and start a tevent queue.
bool tevent_queue_add (struct tevent_queue *queue, struct tevent_context *ev, struct tevent_req *req, tevent_queue_trigger_fn_t trigger, void *private_data)
Add a tevent request to the queue.
struct tevent_queue_entry * tevent_queue_add_entry (struct tevent_queue *queue, struct tevent_context *ev, struct tevent_req *req, tevent_queue_trigger_fn_t trigger, void *private_data)
Add a tevent request to the queue.
struct tevent_queue_entry * tevent_queue_add_optimize_empty (struct tevent_queue *queue, struct tevent_context *ev, struct tevent_req *req, tevent_queue_trigger_fn_t trigger, void *private_data)
Add a tevent request to the queue using a possible optimization.
void tevent_queue_entry_untrigger (struct tevent_queue_entry *entry)
Untrigger an already triggered queue entry.
void tevent_queue_start (struct tevent_queue *queue)
Start a tevent queue.
void tevent_queue_stop (struct tevent_queue *queue)
Stop a tevent queue.
size_t tevent_queue_length (struct tevent_queue *queue)
Get the length of the queue.
bool tevent_queue_running (struct tevent_queue *queue)
Is the tevent queue running.
struct tevent_req * tevent_queue_wait_send (TALLOC_CTX *mem_ctx, struct tevent_context *ev, struct tevent_queue *queue)
Create a tevent subrequest that waits in a tevent_queue.
bool tevent_queue_wait_recv (struct tevent_req *req)
Check if we no longer need to wait in the queue.
struct tevent_thread_proxy * tevent_thread_proxy_create (struct tevent_context *dest_ev_ctx)
Create a tevent_thread_proxy for message passing between threads.
void tevent_thread_proxy_schedule (struct tevent_thread_proxy *tp, struct tevent_immediate **pp_im, tevent_immediate_handler_t handler, void *pp_private_data)
Schedule an immediate event on an event context from another thread.
A tevent_queue is used to queue up async requests that must be serialized.
For example writing buffers into a socket must be serialized. Writing a large lump of data into a socket can require multiple write(2) or send(2) system calls. If more than one async request is outstanding to write large buffers into a socket, every request must individually be completed before the next one begins, even if multiple syscalls are required.
Take a look at The tevent_queue tutorial for more details.
A callback trigger function run by the queue.
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tevent_queue_add_entry()
tevent_queue_add_optimize_empty()
Add a tevent request to the queue.
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Add a tevent request to the queue. The request can be removed from the queue by calling talloc_free() (or a similar function) on the returned queue entry. This is the only difference to tevent_queue_add().
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tevent_queue_add_optimize_empty()
Add a tevent request to the queue using a possible optimization. This tries to optimize for the empty queue case and may calls the trigger function directly. This is the only difference compared to tevent_queue_add_entry().
The caller needs to be prepared that the trigger function has already called tevent_req_notify_callback(), tevent_req_error(), tevent_req_done() or a similar function.
The trigger function has no chance to see the returned queue_entry in the optimized case.
The request can be removed from the queue by calling talloc_free() (or a similar function) on the returned queue entry.
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tevent_queue_add_entry()
Create and start a tevent queue.
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tevent_queue_stop()
Untrigger an already triggered queue entry. If a trigger function detects that it needs to remain in the queue, it needs to call tevent_queue_stop() followed by tevent_queue_entry_untrigger().
Note
You can't use this together with tevent_queue_add_optimize_empty() because the trigger function don't have access to the quene entry in the case of an empty queue.
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tevent_queue_stop()
Get the length of the queue.
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Is the tevent queue running. The queue is started by default.
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Start a tevent queue. The queue is started by default.
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Stop a tevent queue. The queue is started by default.
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Check if we no longer need to wait in the queue. This function needs to be called in the callback function set after calling tevent_queue_wait_send().
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Create a tevent subrequest that waits in a tevent_queue. The idea is that always the same syntax for tevent requests.
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Create a tevent_thread_proxy for message passing between threads. The tevent_context must have been allocated on the NULL talloc context, and talloc_disable_null_tracking() must have been called.
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Schedule an immediate event on an event context from another thread. Causes dest_ev_ctx, being run by another thread, to receive an immediate event calling the handler with the *pp_private parameter.
*pp_im must be a pointer to an immediate event talloced on a context owned by the calling thread, or the NULL context. Ownership will be transferred to the tevent_thread_proxy and *pp_im will be returned as NULL.
*pp_private_data must be a talloced area of memory with no destructors. Ownership of this memory will be transferred to the tevent library and *pp_private_data will be set to NULL on successful completion of the call. Set pp_private to NULL if no parameter transfer needed (a pure callback). This is an asynchronous request, caller does not wait for callback to be completed before returning.
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