lib/latch-windows.c

   1 /*
   2  * Copyright (c) 2013 Nicira, Inc.
   3  *
   4  * Licensed under the Apache License, Version 2.0 (the "License");
   5  * you may not use this file except in compliance with the License.
   6  * You may obtain a copy of the License at:
   7  *
   8  *     http://www.apache.org/licenses/LICENSE-2.0
   9  *
  10  * Unless required by applicable law or agreed to in writing, software
  11  * distributed under the License is distributed on an "AS IS" BASIS,
  12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13  * See the License for the specific language governing permissions and
  14  * limitations under the License.
  15  */
  16
  17 #include <config.h>
  18
  19 #include "latch.h"
  20 #include <errno.h>
  21 #include <poll.h>
  22 #include <unistd.h>
  23 #include "openvswitch/poll-loop.h"
  24 #include "socket-util.h"
  25
  26 /* Initializes 'latch' as initially unset. */
  27 void
  28 latch_init(struct latch *latch)
  29 {
  30     latch->is_set = FALSE;
  31     latch->wevent = CreateEvent(NULL, TRUE, FALSE, NULL);
  32 }
  33
  34 /* Destroys 'latch'. */
  35 void
  36 latch_destroy(struct latch *latch)
  37 {
  38     latch->is_set = FALSE;
  39     CloseHandle(latch->wevent);
  40 }
  41
  42 /* Resets 'latch' to the unset state.  Returns true if 'latch' was previously
  43  * set, false otherwise. */
  44 bool
  45 latch_poll(struct latch *latch)
  46 {
  47     bool is_set;
  48
  49     is_set = latch->is_set;
  50     latch->is_set = FALSE;
  51     ResetEvent(latch->wevent);
  52     return is_set;
  53 }
  54
  55 /* Sets 'latch'.
  56  *
  57  * Calls are not additive: a single latch_poll() clears out any number of
  58  * latch_set(). */
  59 void
  60 latch_set(struct latch *latch)
  61 {
  62     latch->is_set = TRUE;
  63     SetEvent(latch->wevent);
  64 }
  65
  66 /* Returns true if 'latch' is set, false otherwise.  Does not reset 'latch'
  67  * to the unset state. */
  68 bool
  69 latch_is_set(const struct latch *latch)
  70 {
  71     return latch->is_set;
  72 }
  73
  74 /* Causes the next poll_block() to wake up when 'latch' is set.
  75  *
  76  * ('where' is used in debug logging.  Commonly one would use latch_wait() to
  77  * automatically provide the caller's source file and line number for
  78  * 'where'.) */
  79 void
  80 latch_wait_at(const struct latch *latch, const char *where)
  81 {
  82     poll_wevent_wait_at(latch->wevent, where);
  83 }