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Create doxygen comments for async_req.[ch]

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(This used to be commit 1dab45b16a)
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Volker Lendecke 2008-06-28 23:13:05 +02:00
parent 042600cbac
commit bdf1747c98
2 changed files with 162 additions and 45 deletions
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123
source3/include/async_req.h
View File

@ -22,75 +22,116 @@
#include "includes.h"
/*
* An async request moves between the following 4 states.
/**
* An async request moves between the following 4 states:
*/
enum async_req_state {
ASYNC_REQ_INIT, /* we are creating the request */
ASYNC_REQ_IN_PROGRESS, /* we are waiting the request to complete */
ASYNC_REQ_DONE, /* the request is finished */
ASYNC_REQ_ERROR }; /* an error has occured */
/**
* we are creating the request
*/
ASYNC_REQ_INIT,
/**
* we are waiting the request to complete
*/
ASYNC_REQ_IN_PROGRESS,
/**
* the request is finished
*/
ASYNC_REQ_DONE,
/**
* an error has occured
*/
ASYNC_REQ_ERROR
};
/**
* @brief An async request
*
* This represents an async request being processed by callbacks via an event
* context. A user can issue for example a write request to a socket, giving
* an implementation function the fd, the buffer and the number of bytes to
* transfer. The function issuing the request will immediately return without
* blocking most likely without having sent anything. The API user then fills
* in req->async.fn and req->async.priv, functions that are called when the
* request is finished.
*
* It is up to the user of the async request to talloc_free it after it has
* finished. This can happen while the completion function is called.
*/
struct async_req {
/* the external state - will be queried by the caller */
/**
* @brief The external state - will be queried by the caller
*
* While the async request is being processed, state will remain in
* ASYNC_REQ_IN_PROGRESS. A request is finished if
* req->state>=ASYNC_REQ_DONE.
*/
enum async_req_state state;
/* a private pointer for use by the async function implementation */
/**
* @brief Private pointer for the actual implementation
*
* The implementation doing the work for the async request needs a
* current state like for example a fd event. The user of an async
* request should not touch this.
*/
void *private_data;
/* print yourself, for debugging purposes */
/**
* @brief Print yourself, for debugging purposes
*
* Async requests are opaque data structures. The implementation of an
* async request can define a custom function to print more debug
* info.
*/
char *(*print)(TALLOC_CTX *mem_ctx, struct async_req *);
/* status code when finished */
/**
* @brief status code when finished
*
* This status can be queried in the async completion function. It
* will be set to NT_STATUS_OK when everything went fine.
**/
NTSTATUS status;
/* the event context we are using */
/**
* @brief The event context we are using
*
* The event context that this async request works on.
*/
struct event_context *event_ctx;
/* information on what to do on completion */
/**
* @brief What to do on completion
*
* This is used for the user of an async request, fn is called when
* the request completes, either successfully or with an error.
*/
struct {
/**
* @brief Completion function
* Completion function, to be filled by the API user
*/
void (*fn)(struct async_req *);
/**
* @brief Private data for the completion function
*/
void *priv;
} async;
};
/*
* Print an async_req structure for debugging purposes
*/
char *async_req_print(TALLOC_CTX *mem_ctx, struct async_req *req);
/*
* Create an async request
*/
struct async_req *async_req_new(TALLOC_CTX *mem_ctx, struct event_context *ev);
/*
* An async request has successfully finished, invoke the callback
*/
char *async_req_print(TALLOC_CTX *mem_ctx, struct async_req *req);
void async_req_done(struct async_req *req);
/*
* An async request has seen an error, invoke the callback
*/
void async_req_error(struct async_req *req, NTSTATUS status);
/*
* If a request is finished or ends in error even before it has the chance to
* trigger the event loop, post a status. This creates an immediate timed
* event to call the async function if there is any.
*/
bool async_post_status(struct async_req *req, NTSTATUS status);
/*
* Convenience helper to easily check alloc failure within a callback.
*
* Call pattern would be
* p = talloc(mem_ctx, bla);
* if (async_req_nomem(p, req)) {
* return;
* }
*
*/
bool async_req_nomem(const void *p, struct async_req *req);
#endif

84
source3/lib/async_req.c
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@ -19,6 +19,20 @@
#include "includes.h"
/**
* @brief Print an async_req structure
* @param[in] mem_ctx The memory context for the result
* @param[in] req The request to be printed
* @retval Text representation of req
*
* This is a default print function for async requests. Implementations should
* override this with more specific information.
*
* This function should not be used by async API users, this is non-static
* only to allow implementations to easily provide default information in
* their specific functions.
*/
char *async_req_print(TALLOC_CTX *mem_ctx, struct async_req *req)
{
return talloc_asprintf(mem_ctx, "async_req: state=%d, status=%s, "
@ -26,6 +40,15 @@ char *async_req_print(TALLOC_CTX *mem_ctx, struct async_req *req)
talloc_get_name(req->private_data));
}
/**
* @brief Create an async request
* @param[in] mem_ctx The memory context for the result
* @param[in] ev The event context this async request will be driven by
* @retval A new async request
*
* The new async request will be initialized in state ASYNC_REQ_IN_PROGRESS
*/
struct async_req *async_req_new(TALLOC_CTX *mem_ctx, struct event_context *ev)
{
struct async_req *result;
@ -40,6 +63,15 @@ struct async_req *async_req_new(TALLOC_CTX *mem_ctx, struct event_context *ev)
return result;
}
/**
* @brief An async request has successfully finished
* @param[in] req The finished request
*
* async_req_done is to be used by implementors of async requests. When a
* request is successfully finished, this function calls the user's completion
* function.
*/
void async_req_done(struct async_req *req)
{
req->status = NT_STATUS_OK;
@ -49,6 +81,16 @@ void async_req_done(struct async_req *req)
}
}
/**
* @brief An async request has seen an error
* @param[in] req The request with an error
* @param[in] status The error code
*
* async_req_done is to be used by implementors of async requests. When a
* request can not successfully completed, the implementation should call this
* function with the appropriate status code.
*/
void async_req_error(struct async_req *req, NTSTATUS status)
{
req->status = status;
@ -58,6 +100,14 @@ void async_req_error(struct async_req *req, NTSTATUS status)
}
}
/**
* @brief Timed event callback
* @param[in] ev Event context
* @param[in] te The timed event
* @param[in] now current time
* @param[in] priv The async request to be finished
*/
static void async_trigger(struct event_context *ev, struct timed_event *te,
const struct timeval *now, void *priv)
{
@ -72,12 +122,21 @@ static void async_trigger(struct event_context *ev, struct timed_event *te,
}
}
/**
* @brief Finish a request before it started processing
* @param[in] req The finished request
* @param[in] status The success code
*
* An implementation of an async request might find that it can either finish
* the request without waiting for an external event, or it can't even start
* the engine. To present the illusion of a callback to the user of the API,
* the implementation can call this helper function which triggers an
* immediate timed event. This way the caller can use the same calling
* conventions, independent of whether the request was actually deferred.
*/
bool async_post_status(struct async_req *req, NTSTATUS status)
{
/*
* Used if a request is finished before it even started
*/
req->status = status;
if (event_add_timed(req->event_ctx, req, timeval_zero(),
@ -88,6 +147,23 @@ bool async_post_status(struct async_req *req, NTSTATUS status)
return true;
}
/**
* @brief Helper function for nomem check
* @param[in] p The pointer to be checked
* @param[in] req The request being processed
*
* Convenience helper to easily check alloc failure within a callback
* implementing the next step of an async request.
*
* Call pattern would be
* \code
* p = talloc(mem_ctx, bla);
* if (async_req_nomem(p, req)) {
* return;
* }
* \endcode
*/
bool async_req_nomem(const void *p, struct async_req *req)
{
if (p != NULL) {