Add some examples for using libmysqld, including a hack for running the

mysql test suite.

A few minor libmysqld fixes.

Add mysql_server_init() and _end() to mysql.cc and mysqltest.c, so they
can be linked against libmysqlclient or libmysqld.

libmysqld/libmysqld.c

@@ -98,6 +98,11 @@ static ulong mysql_sub_escape_string(CHARSET_INFO *charset_info, char *to,
 #define set_sigpipe(mysql)
 #define reset_sigpipe(mysql)
 
+static MYSQL* spawn_init(MYSQL* parent, const char* host,
+			 unsigned int port,
+			 const char* user,
+			 const char* passwd);
+
 /*****************************************************************************
 ** read a packet from server. Give error message if socket was down
 ** or packet is an error message
@@ -762,6 +767,301 @@ read_one_row(MYSQL *mysql,uint fields,MYSQL_ROW row, ulong *lengths)
   return 0;
 }
 
+/* perform query on master */
+int STDCALL mysql_master_query(MYSQL *mysql, const char *q,
+					unsigned int length)
+{
+  if(mysql_master_send_query(mysql, q, length))
+    return 1;
+  return mysql_read_query_result(mysql);
+}
+
+int STDCALL mysql_master_send_query(MYSQL *mysql, const char *q,
+					unsigned int length)
+{
+  MYSQL*master = mysql->master;
+  if (!length)
+    length = strlen(q);
+  if (!master->net.vio && !mysql_real_connect(master,0,0,0,0,0,0,0))
+    return 1;
+  mysql->last_used_con = master;
+  return simple_command(master, COM_QUERY, q, length, 1);
+}
+
+
+/* perform query on slave */  
+int STDCALL mysql_slave_query(MYSQL *mysql, const char *q,
+					unsigned int length)
+{
+  if(mysql_slave_send_query(mysql, q, length))
+    return 1;
+  return mysql_read_query_result(mysql);
+}
+
+int STDCALL mysql_slave_send_query(MYSQL *mysql, const char *q,
+					unsigned int length)
+{
+  MYSQL* last_used_slave, *slave_to_use = 0;
+  
+  if((last_used_slave = mysql->last_used_slave))
+    slave_to_use = last_used_slave->next_slave;
+  else
+    slave_to_use = mysql->next_slave;
+  /* next_slave is always safe to use - we have a circular list of slaves
+     if there are no slaves, mysql->next_slave == mysql
+  */
+  mysql->last_used_con = mysql->last_used_slave = slave_to_use;
+  if(!length)
+    length = strlen(q);
+  if(!slave_to_use->net.vio && !mysql_real_connect(slave_to_use, 0,0,0,
+						   0,0,0,0))
+    return 1;
+  return simple_command(slave_to_use, COM_QUERY, q, length, 1);
+}
+
+
+/* enable/disable parsing of all queries to decide
+   if they go on master or slave */
+void STDCALL mysql_enable_rpl_parse(MYSQL* mysql)
+{
+  mysql->options.rpl_parse = 1;
+}
+
+void STDCALL mysql_disable_rpl_parse(MYSQL* mysql)
+{
+  mysql->options.rpl_parse = 0;
+}
+
+/* get the value of the parse flag */  
+int STDCALL mysql_rpl_parse_enabled(MYSQL* mysql)
+{
+  return mysql->options.rpl_parse;
+}
+
+/*  enable/disable reads from master */
+void STDCALL mysql_enable_reads_from_master(MYSQL* mysql)
+{
+  mysql->options.no_master_reads = 0;
+}
+
+void STDCALL mysql_disable_reads_from_master(MYSQL* mysql)
+{
+  mysql->options.no_master_reads = 1;
+}
+
+/* get the value of the master read flag */  
+int STDCALL mysql_reads_from_master_enabled(MYSQL* mysql)
+{
+  return !(mysql->options.no_master_reads);
+}
+
+/* We may get an error while doing replication internals.
+   In this case, we add a special explanation to the original
+   error
+*/
+static inline void expand_error(MYSQL* mysql, int error)
+{
+  char tmp[MYSQL_ERRMSG_SIZE];
+  char* p, *tmp_end;
+  tmp_end = strnmov(tmp, mysql->net.last_error, MYSQL_ERRMSG_SIZE);
+  p = strnmov(mysql->net.last_error, ER(error), MYSQL_ERRMSG_SIZE);
+  memcpy(p, tmp, tmp_end - tmp);
+  mysql->net.last_errno = error;
+}
+
+/* This function assumes we have just called SHOW SLAVE STATUS and have
+   read the given result and row
+*/
+static inline int get_master(MYSQL* mysql, MYSQL_RES* res, MYSQL_ROW row)
+{
+  MYSQL* master;
+  if(mysql_num_fields(res) < 3)
+    return 1; /* safety */
+  
+  /* use the same username and password as the original connection */
+  if(!(master = spawn_init(mysql, row[0], atoi(row[2]), 0, 0)))
+    return 1;
+  mysql->master = master;
+  return 0;
+}
+
+/* assuming we already know that mysql points to a master connection,
+   retrieve all the slaves
+*/
+static inline int get_slaves_from_master(MYSQL* mysql)
+{
+  MYSQL_RES* res = 0;
+  MYSQL_ROW row;
+  int error = 1;
+  int has_auth_info;
+  if (!mysql->net.vio && !mysql_real_connect(mysql,0,0,0,0,0,0,0))
+  {
+    expand_error(mysql, CR_PROBE_MASTER_CONNECT);
+    return 1;
+  }
+
+  if (mysql_query(mysql, "SHOW SLAVE HOSTS") ||
+     !(res = mysql_store_result(mysql)))
+  {
+    expand_error(mysql, CR_PROBE_SLAVE_HOSTS);
+    return 1;
+  }
+
+  switch (mysql_num_fields(res))
+  {
+  case 3: has_auth_info = 0; break;
+  case 5: has_auth_info = 1; break;
+  default:
+    goto err;
+  }
+
+  while ((row = mysql_fetch_row(res)))
+  {
+    MYSQL* slave;
+    const char* tmp_user, *tmp_pass;
+
+    if (has_auth_info)
+    {
+      tmp_user = row[3];
+      tmp_pass = row[4];
+    }
+    else
+    {
+      tmp_user = mysql->user;
+      tmp_pass = mysql->passwd;
+    }
+
+    if(!(slave = spawn_init(mysql, row[1], atoi(row[2]),
+			    tmp_user, tmp_pass)))
+      goto err;
+      
+    /* Now add slave into the circular linked list */
+    slave->next_slave = mysql->next_slave;
+    mysql->next_slave = slave;
+  }
+  error = 0;
+err:
+  if(res)
+   mysql_free_result(res);
+  return error;
+}
+
+int STDCALL mysql_rpl_probe(MYSQL* mysql)
+{
+  MYSQL_RES* res = 0;
+  MYSQL_ROW row;
+  int error = 1;
+  /* first determine the replication role of the server we connected to
+     the most reliable way to do this is to run SHOW SLAVE STATUS and see
+     if we have a non-empty master host. This is still not fool-proof -
+     it is not a sin to have a master that has a dormant slave thread with
+     a non-empty master host. However, it is more reliable to check 
+     for empty master than whether the slave thread is actually running
+  */
+  if (mysql_query(mysql, "SHOW SLAVE STATUS") ||
+     !(res = mysql_store_result(mysql)))
+  {
+    expand_error(mysql, CR_PROBE_SLAVE_STATUS);
+    return 1;
+  }
+  
+  if (!(row = mysql_fetch_row(res)))
+    goto err;
+
+  /* check master host for emptiness/NULL */
+  if (row[0] && *(row[0]))
+  {
+    /* this is a slave, ask it for the master */
+    if (get_master(mysql, res, row) || get_slaves_from_master(mysql))
+      goto err;
+  }
+  else
+  {
+    mysql->master = mysql;
+    if (get_slaves_from_master(mysql))
+      goto err;
+  }
+
+  error = 0;
+err:
+  if(res)
+    mysql_free_result(res);
+  return error;
+}
+
+
+/* make a not so fool-proof decision on where the query should go, to
+   the master or the slave. Ideally the user should always make this
+   decision himself with mysql_master_query() or mysql_slave_query().
+   However, to be able to more easily port the old code, we support the
+   option of an educated guess - this should work for most applications,
+   however, it may make the wrong decision in some particular cases. If
+   that happens, the user would have to change the code to call
+   mysql_master_query() or mysql_slave_query() explicitly in the place
+   where we have made the wrong decision
+*/
+enum mysql_rpl_type
+STDCALL mysql_rpl_query_type(const char* q, int len)
+{
+  const char* q_end;
+  q_end = (len) ? q + len : strend(q);
+  for(; q < q_end; ++q)
+  {
+    char c;
+    if(isalpha(c=*q))
+      switch(tolower(c))
+       {
+       case 'i':  /* insert */
+       case 'u':  /* update or unlock tables */
+       case 'l':  /* lock tables or load data infile */
+       case 'd':  /* drop or delete */
+       case 'a':  /* alter */
+	 return MYSQL_RPL_MASTER;
+       case 'c':  /* create or check */
+	 return tolower(q[1]) == 'h' ? MYSQL_RPL_ADMIN : MYSQL_RPL_MASTER ;
+       case 's': /* select or show */
+	 return tolower(q[1] == 'h') ? MYSQL_RPL_ADMIN : MYSQL_RPL_SLAVE;
+       case 'f': /* flush */
+       case 'r': /* repair */
+       case 'g': /* grant */
+	 return MYSQL_RPL_ADMIN;
+       default:
+	 return MYSQL_RPL_SLAVE;
+       }
+  }
+
+  return 0;
+}
+
+static MYSQL* spawn_init(MYSQL* parent, const char* host,
+					   unsigned int port,
+					   const char* user,
+					   const char* passwd)
+{
+  MYSQL* child;
+  if (!(child = mysql_init(0)))
+    return 0;
+  
+  child->options.user = my_strdup((user) ? user :
+				  (parent->user ? parent->user :
+				       parent->options.user), MYF(0));
+  child->options.password = my_strdup((passwd) ? passwd : (parent->passwd ?
+						    parent->passwd :
+				       parent->options.password), MYF(0));
+  child->options.port = port;
+  child->options.host = my_strdup((host) ? host : (parent->host ?
+						    parent->host :
+				       parent->options.host), MYF(0));
+  if(parent->db)
+    child->options.db = my_strdup(parent->db, MYF(0));
+  else if(parent->options.db)
+    child->options.db = my_strdup(parent->options.db, MYF(0));
+
+  child->options.rpl_parse = child->options.rpl_probe = child->rpl_pivot = 0;
+    
+  return child;
+}
+
 /****************************************************************************
 ** Init MySQL structure or allocate one
 ****************************************************************************/