ovsdb/log.h

   1 /* Copyright (c) 2009, 2010, 2011, 2017 Nicira, Inc.
   2  *
   3  * Licensed under the Apache License, Version 2.0 (the "License");
   4  * you may not use this file except in compliance with the License.
   5  * You may obtain a copy of the License at:
   6  *
   7  *     http://www.apache.org/licenses/LICENSE-2.0
   8  *
   9  * Unless required by applicable law or agreed to in writing, software
  10  * distributed under the License is distributed on an "AS IS" BASIS,
  11  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  12  * See the License for the specific language governing permissions and
  13  * limitations under the License.
  14  */
  15
  16 #ifndef OVSDB_LOG_H
  17 #define OVSDB_LOG_H 1
  18
  19 /* OVSDB log.
  20  *
  21  * A log consists of a series of records.  After opening or creating a log with
  22  * ovsdb_log_open(), the client may use ovsdb_log_read() to read any existing
  23  * records, one by one.  The client may also use ovsdb_log_write() to write new
  24  * records (if some records have not yet been read at this point, then the
  25  * first write truncates them).
  26  *
  27  * Log writes are atomic.  A client may use ovsdb_log_commit() to ensure that
  28  * they are durable.
  29  *
  30  * Logs provide a mechansim to allow the client to tell when they have grown
  31  * enough that compacting may be warranted.  After reading existing log
  32  * contents, the client uses ovsdb_log_mark_base() to mark the "base" to be
  33  * considered as the initial size of the log.  Thereafter, a client may call
  34  * ovsdb_log_grew_lots() to get an indication whether the log has grown enough
  35  * that compacting is advised.
  36  */
  37
  38 #include <stdint.h>
  39 #include <sys/types.h>
  40 #include "compiler.h"
  41
  42 struct ds;
  43 struct json;
  44 struct ovsdb_log;
  45
  46 /* Access mode for opening an OVSDB log. */
  47 enum ovsdb_log_open_mode {
  48     OVSDB_LOG_READ_ONLY,        /* Open existing file, read-only. */
  49     OVSDB_LOG_READ_WRITE,       /* Open existing file, read/write. */
  50     OVSDB_LOG_CREATE_EXCL,      /* Create new file, read/write. */
  51     OVSDB_LOG_CREATE            /* Create or open file, read/write. */
  52 };
  53
  54 /* 'magic' for use with ovsdb_log_open() for OVSDB databases (see ovsdb(5)). */
  55 #define OVSDB_MAGIC "JSON"
  56
  57 struct ovsdb_error *ovsdb_log_open(const char *name, const char *magic,
  58                                    enum ovsdb_log_open_mode,
  59                                    int locking, struct ovsdb_log **)
  60     OVS_WARN_UNUSED_RESULT;
  61 void ovsdb_log_close(struct ovsdb_log *);
  62
  63 const char *ovsdb_log_get_magic(const struct ovsdb_log *);
  64
  65 struct ovsdb_error *ovsdb_log_read(struct ovsdb_log *, struct json **)
  66     OVS_WARN_UNUSED_RESULT;
  67 void ovsdb_log_unread(struct ovsdb_log *);
  68
  69 void ovsdb_log_compose_record(const struct json *, const char *magic,
  70                               struct ds *header, struct ds *data);
  71
  72 struct ovsdb_error *ovsdb_log_write(struct ovsdb_log *, const struct json *)
  73     OVS_WARN_UNUSED_RESULT;
  74 struct ovsdb_error *ovsdb_log_write_and_free(struct ovsdb_log *, struct json *)
  75     OVS_WARN_UNUSED_RESULT;
  76
  77 uint64_t ovsdb_log_commit_start(struct ovsdb_log *);
  78 uint64_t ovsdb_log_commit_progress(struct ovsdb_log *);
  79 void ovsdb_log_commit_wait(struct ovsdb_log *, uint64_t);
  80 struct ovsdb_error *ovsdb_log_commit_block(struct ovsdb_log *)
  81     OVS_WARN_UNUSED_RESULT;
  82
  83 void ovsdb_log_mark_base(struct ovsdb_log *);
  84 bool ovsdb_log_grew_lots(const struct ovsdb_log *);
  85
  86 struct ovsdb_error *ovsdb_log_replace(struct ovsdb_log *,
  87                                       struct json **entries, size_t n)
  88     OVS_WARN_UNUSED_RESULT;
  89 struct ovsdb_error *ovsdb_log_replace_start(struct ovsdb_log *old,
  90                                             struct ovsdb_log **newp)
  91     OVS_WARN_UNUSED_RESULT;
  92 struct ovsdb_error *ovsdb_log_replace_commit(struct ovsdb_log *old,
  93                                              struct ovsdb_log *new)
  94     OVS_WARN_UNUSED_RESULT;
  95 void ovsdb_log_replace_abort(struct ovsdb_log *new);
  96
  97 /* For testing. */
  98 void ovsdb_log_disable_renaming_open_files(void);
  99
 100 #endif /* ovsdb/log.h */