text: #ifndef TARANTOOL_WAL_WRITER_H_INCLUDED
  #define TARANTOOL_WAL_WRITER_H_INCLUDED
  /*
   * Copyright 2010-2015, 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 "cbus.h"
  #include "small/rlist.h"
  
  struct fiber;
  struct recovery;
  
  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[];
  
  #if defined(__cplusplus)
  
  struct wal_request: public cmsg {
  	/* Auxiliary. */
  	int64_t res;
  	struct fiber *fiber;
  	/* Relative position of the start of request (used for rollback) */
  	off_t start_offset;
  	/* Relative position of the end of request (used for rollback) */
  	off_t end_offset;
  	int n_rows;
  	struct xrow_header *rows[];
  };
  
  int64_t
  wal_write(struct recovery *r, struct wal_request *req);
  
  int
  wal_writer_start(struct recovery *state, int64_t rows_per_wal);
  
  void
  wal_writer_stop(struct recovery *r);
  
  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_register_watcher(
  	struct recovery *, struct wal_watcher *, struct ev_async *);
  
  void
  wal_unregister_watcher(
  	struct recovery *, struct wal_watcher *);
  
  #endif /* defined(__cplusplus) */
  
  #endif /* TARANTOOL_WAL_WRITER_H_INCLUDED */
  