text: #ifndef TARANTOOL_WAL_WRITER_H_INCLUDED
  #define TARANTOOL_WAL_WRITER_H_INCLUDED
  /*
   * Copyright 2010-2016, Tarantool AUTHORS, please see AUTHORS file.
   *
   * Redistribution and use in source and binary forms, with or
   * without modification, are permitted provided that the following
   * conditions are met:
   *
   * 1. Redistributions of source code must retain the above
   *    copyright notice, this list of conditions and the
   *    following disclaimer.
   *
   * 2. Redistributions in binary form must reproduce the above
   *    copyright notice, this list of conditions and the following
   *    disclaimer in the documentation and/or other materials
   *    provided with the distribution.
   *
   * THIS SOFTWARE IS PROVIDED BY <COPYRIGHT HOLDER> ``AS IS'' AND
   * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
   * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
   * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
   * <COPYRIGHT HOLDER> OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
   * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
   * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
   * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
   * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
   * THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   * SUCH DAMAGE.
   */
  #include <stdint.h>
  #include <sys/types.h>
  #include "small/rlist.h"
  #include "journal.h"
  
  struct fiber;
  struct vclock;
  struct wal_writer;
  
  enum wal_mode { WAL_NONE = 0, WAL_WRITE, WAL_FSYNC, WAL_MODE_MAX };
  
  /** String constants for the supported modes. */
  extern const char *wal_mode_STRS[];
  
  extern int wal_dir_lock;
  
  #if defined(__cplusplus)
  
  void
  wal_thread_start();
  
  void
  wal_init(enum wal_mode wal_mode, const char *wal_dirname,
  	 const struct tt_uuid *instance_uuid, struct vclock *vclock,
  	 int64_t wal_max_rows, int64_t wal_max_size);
  
  enum wal_mode
  wal_mode();
  
  void
  wal_thread_stop();
  
  struct wal_watcher
  {
  	struct rlist next;
  	struct ev_loop *loop;
  	struct ev_async *async;
  };
  
  /**
   * Receive a notification the next time a wal_write is completed
   * (+unspecified but reasonable latency).
   * Fails (-1) if recovery is NULL or lacking a WAL writer.
   */
  int
  wal_set_watcher(struct wal_watcher *, struct ev_async *);
  
  void
  wal_clear_watcher(struct wal_watcher *);
  
  void
  wal_atfork();
  
  extern "C" {
  #endif /* defined(__cplusplus) */
  
  /**
   * Wait till all pending changes to the WAL are flushed.
   * Rotates the WAL.
   *
   * @param[out] vclock WAL vclock
   *
   */
  int
  wal_checkpoint(struct vclock *vclock, bool rotate);
  
  /**
   * Remove WAL files that are not needed to recover
   * from snapshot with @lsn or newer.
   */
  void
  wal_collect_garbage(int64_t lsn);
  
  void
  wal_init_vy_log();
  
  /**
   * Write xrows to the vinyl metadata log.
   */
  int
  wal_write_vy_log(struct journal_entry *req);
  
  /**
   * Rotate the vinyl metadata log.
   */
  void
  wal_rotate_vy_log();
  
  #if defined(__cplusplus)
  } /* extern "C" */
  #endif /* defined(__cplusplus) */
  
  #endif /* TARANTOOL_WAL_WRITER_H_INCLUDED */
  