text: /*
   * CDDL HEADER START
   *
   * The contents of this file are subject to the terms of the
   * Common Development and Distribution License (the "License").
   * You may not use this file except in compliance with the License.
   *
   * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
   * or http://www.opensolaris.org/os/licensing.
   * See the License for the specific language governing permissions
   * and limitations under the License.
   *
   * When distributing Covered Code, include this CDDL HEADER in each
   * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
   * If applicable, add the following below this CDDL HEADER, with the
   * fields enclosed by brackets "[]" replaced with your own identifying
   * information: Portions Copyright [yyyy] [name of copyright owner]
   *
   * CDDL HEADER END
   */
  /*
   * Copyright (c) 2010, Oracle and/or its affiliates. All rights reserved.
   * Copyright (c) 2012 by Delphix. All rights reserved.
   */
  
  #include <sys/zfs_context.h>
  
  list_t zfs_dbgmsgs;
  int zfs_dbgmsg_size;
  kmutex_t zfs_dbgmsgs_lock;
  int zfs_dbgmsg_maxsize = 1<<20; /* 1MB */
  
  void
  zfs_dbgmsg_init(void)
  {
  	list_create(&zfs_dbgmsgs, sizeof (zfs_dbgmsg_t),
  	    offsetof(zfs_dbgmsg_t, zdm_node));
  	mutex_init(&zfs_dbgmsgs_lock, NULL, MUTEX_DEFAULT, NULL);
  }
  
  void
  zfs_dbgmsg_fini(void)
  {
  	zfs_dbgmsg_t *zdm;
  
  	while ((zdm = list_remove_head(&zfs_dbgmsgs)) != NULL) {
  		int size = sizeof (zfs_dbgmsg_t) + strlen(zdm->zdm_msg);
  		kmem_free(zdm, size);
  		zfs_dbgmsg_size -= size;
  	}
  	mutex_destroy(&zfs_dbgmsgs_lock);
  	ASSERT0(zfs_dbgmsg_size);
  }
  
  /*
   * Print these messages by running:
   * echo ::zfs_dbgmsg | mdb -k
   *
   * Monitor these messages by running:
   * 	dtrace -q -n 'zfs-dbgmsg{printf("%s\n", stringof(arg0))}'
   */
  void
  zfs_dbgmsg(const char *fmt, ...)
  {
  	int size;
  	va_list adx;
  	zfs_dbgmsg_t *zdm;
  
  	va_start(adx, fmt);
  	size = vsnprintf(NULL, 0, fmt, adx);
  	va_end(adx);
  
  	/*
  	 * There is one byte of string in sizeof (zfs_dbgmsg_t), used
  	 * for the terminating null.
  	 */
  	zdm = kmem_alloc(sizeof (zfs_dbgmsg_t) + size, KM_SLEEP);
  	zdm->zdm_timestamp = gethrestime_sec();
  
  	va_start(adx, fmt);
  	(void) vsnprintf(zdm->zdm_msg, size + 1, fmt, adx);
  	va_end(adx);
  
  	DTRACE_PROBE1(zfs__dbgmsg, char *, zdm->zdm_msg);
  
  	mutex_enter(&zfs_dbgmsgs_lock);
  	list_insert_tail(&zfs_dbgmsgs, zdm);
  	zfs_dbgmsg_size += sizeof (zfs_dbgmsg_t) + size;
  	while (zfs_dbgmsg_size > zfs_dbgmsg_maxsize) {
  		zdm = list_remove_head(&zfs_dbgmsgs);
  		size = sizeof (zfs_dbgmsg_t) + strlen(zdm->zdm_msg);
  		kmem_free(zdm, size);
  		zfs_dbgmsg_size -= size;
  	}
  	mutex_exit(&zfs_dbgmsgs_lock);
  }
  