source/include/async_req.h

   1 /*
   2    Unix SMB/CIFS implementation.
   3    Infrastructure for async requests
   4    Copyright (C) Volker Lendecke 2008
   5
   6    This program is free software; you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 3 of the License, or
   9    (at your option) any later version.
  10
  11    This program is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  18 */
  19
  20 #ifndef __ASYNC_REQ_H__
  21 #define __ASYNC_REQ_H__
  22
  23 #include "includes.h"
  24
  25 /**
  26  * An async request moves between the following 4 states:
  27  */
  28
  29 enum async_req_state {
  30         /**
  31          * we are creating the request
  32          */
  33         ASYNC_REQ_INIT,
  34         /**
  35          * we are waiting the request to complete
  36          */
  37         ASYNC_REQ_IN_PROGRESS,
  38         /**
  39          * the request is finished
  40          */
  41         ASYNC_REQ_DONE,
  42         /**
  43          * an error has occured
  44          */
  45         ASYNC_REQ_ERROR
  46 };
  47
  48 /**
  49  * @brief An async request
  50  *
  51  * This represents an async request being processed by callbacks via an event
  52  * context. A user can issue for example a write request to a socket, giving
  53  * an implementation function the fd, the buffer and the number of bytes to
  54  * transfer. The function issuing the request will immediately return without
  55  * blocking most likely without having sent anything. The API user then fills
  56  * in req->async.fn and req->async.priv, functions that are called when the
  57  * request is finished.
  58  *
  59  * It is up to the user of the async request to talloc_free it after it has
  60  * finished. This can happen while the completion function is called.
  61  */
  62
  63 struct async_req {
  64         /**
  65          * @brief The external state - will be queried by the caller
  66          *
  67          * While the async request is being processed, state will remain in
  68          * ASYNC_REQ_IN_PROGRESS. A request is finished if
  69          * req->state>=ASYNC_REQ_DONE.
  70          */
  71         enum async_req_state state;
  72
  73         /**
  74          * @brief Private pointer for the actual implementation
  75          *
  76          * The implementation doing the work for the async request needs a
  77          * current state like for example a fd event. The user of an async
  78          * request should not touch this.
  79          */
  80         void *private_data;
  81
  82         /**
  83          * @brief Print yourself, for debugging purposes
  84          *
  85          * Async requests are opaque data structures. The implementation of an
  86          * async request can define a custom function to print more debug
  87          * info.
  88          */
  89         char *(*print)(TALLOC_CTX *mem_ctx, struct async_req *);
  90
  91         /**
  92          * @brief status code when finished
  93          *
  94          * This status can be queried in the async completion function. It
  95          * will be set to NT_STATUS_OK when everything went fine.
  96          **/
  97         NTSTATUS status;
  98
  99         /**
 100          * @brief The event context we are using
 101          *
 102          * The event context that this async request works on.
 103          */
 104         struct event_context *event_ctx;
 105
 106         /**
 107          * @brief What to do on completion
 108          *
 109          * This is used for the user of an async request, fn is called when
 110          * the request completes, either successfully or with an error.
 111          */
 112         struct {
 113                 /**
 114                  * @brief Completion function
 115                  * Completion function, to be filled by the API user
 116                  */
 117                 void (*fn)(struct async_req *);
 118                 /**
 119                  * @brief Private data for the completion function
 120                  */
 121                 void *priv;
 122         } async;
 123 };
 124
 125 struct async_req *async_req_new(TALLOC_CTX *mem_ctx, struct event_context *ev);
 126
 127 char *async_req_print(TALLOC_CTX *mem_ctx, struct async_req *req);
 128
 129 void async_req_done(struct async_req *req);
 130
 131 void async_req_error(struct async_req *req, NTSTATUS status);
 132
 133 bool async_post_status(struct async_req *req, NTSTATUS status);
 134
 135 bool async_req_nomem(const void *p, struct async_req *req);
 136
 137 #endif