lib/versions.h

   1 /*
   2  * Copyright (c) 2016 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 #ifndef VERSIONS_H
  18 #define VERSIONS_H 1
  19
  20 #include "ovs-atomic.h"
  21 #include "openvswitch/type-props.h"
  22
  23 typedef uint64_t ovs_version_t;
  24
  25 #define OVS_VERSION_MIN 0                  /* Default version number to use. */
  26 #define OVS_VERSION_MAX (TYPE_MAXIMUM(ovs_version_t) - 1)
  27 #define OVS_VERSION_NOT_REMOVED TYPE_MAXIMUM(ovs_version_t)
  28
  29 /*
  30  * OVS_VERSION_NOT_REMOVED has a special meaning for 'remove_version',
  31  * meaning that the rule has been added but not yet removed.
  32  */
  33 struct versions {
  34     ovs_version_t add_version;              /* Version object was added in. */
  35     ATOMIC(ovs_version_t) remove_version;   /* Version object is removed in. */
  36 };
  37
  38 #define VERSIONS_INITIALIZER(ADD, REMOVE) \
  39     (struct versions){ ADD, ATOMIC_VAR_INIT(REMOVE) }
  40
  41 static inline void
  42 versions_set_remove_version(struct versions *versions, ovs_version_t version)
  43 {
  44     atomic_store_relaxed(&versions->remove_version, version);
  45 }
  46
  47 static inline bool
  48 versions_visible_in_version(const struct versions *versions,
  49                             ovs_version_t version)
  50 {
  51     ovs_version_t remove_version;
  52
  53     /* C11 does not want to access an atomic via a const object pointer. */
  54     atomic_read_relaxed(&CONST_CAST(struct versions *,
  55                                     versions)->remove_version,
  56                         &remove_version);
  57
  58     return versions->add_version <= version && version < remove_version;
  59 }
  60
  61 static inline bool
  62 versions_is_eventually_invisible(const struct versions *versions)
  63 {
  64     ovs_version_t remove_version;
  65
  66     /* C11 does not want to access an atomic via a const object pointer. */
  67     atomic_read_relaxed(&CONST_CAST(struct versions *,
  68                                     versions)->remove_version,
  69                         &remove_version);
  70
  71     return remove_version < OVS_VERSION_NOT_REMOVED;
  72 }
  73
  74 #endif /* VERSIONS_H */