MDEV-7273 - 10.1 fails to start up during tc_log initializations on PPC64

log-tc-size is 24K by default. Page size is 64K on PPC64. But log-tc-size
must be at least 3 x page size. This is enforced by TC_LOG_MMAP::open()
with a comment: to guarantee non-empty pool.

This all makes server not startable in default configuration on PPC64.

Autosize log-tc-size, so that it's min value= page size * 3, default
value= page size * 6, block size= page size.

mysql-test/r/mysqld--help.result

@@ -1199,7 +1199,6 @@ log-slow-rate-limit 1
 log-slow-slave-statements FALSE
 log-slow-verbosity 
 log-tc tc.log
-log-tc-size 24576
 log-warnings 1
 long-query-time 10
 low-priority-updates FALSE

mysql-test/suite/sys_vars/inc/sysvars_server.inc

@@ -28,7 +28,7 @@ select * from information_schema.system_variables
           'system_time_zone',
           'version_comment',
           'version_compile_machine', 'version_compile_os',
-          'version_malloc_library', 'version'
+          'version_malloc_library', 'log_tc_size', 'version'
         )
   order by variable_name;
 
@@ -53,4 +53,13 @@ select VARIABLE_NAME, VARIABLE_SCOPE, VARIABLE_TYPE, VARIABLE_COMMENT,
         )
   order by variable_name;
 
+# yet less data: no values, no blocks size, no min/max value.
+select VARIABLE_NAME, GLOBAL_VALUE_ORIGIN, VARIABLE_SCOPE, VARIABLE_TYPE,
+       VARIABLE_COMMENT, ENUM_VALUE_LIST, READ_ONLY, COMMAND_LINE_ARGUMENT
+  from information_schema.system_variables
+  where variable_name in (
+          'log_tc_size'
+        )
+  order by variable_name;
+
 set global div_precision_increment=default;

mysql-test/suite/sys_vars/r/log_tc_size_basic.result

+SET GLOBAL log_tc_size=1;
+ERROR HY000: Variable 'log_tc_size' is a read only variable
+SET SESSION log_tc_size=1;
+ERROR HY000: Variable 'log_tc_size' is a read only variable

mysql-test/suite/sys_vars/r/sysvars_server_notembedded.result

@@ -18,7 +18,7 @@ variable_name not in (
 'system_time_zone',
 'version_comment',
 'version_compile_machine', 'version_compile_os',
-'version_malloc_library', 'version'
+'version_malloc_library', 'log_tc_size', 'version'
         )
 order by variable_name;
 VARIABLE_NAME	AUTOCOMMIT
@@ -4887,4 +4887,19 @@ NUMERIC_BLOCK_SIZE	NULL
 ENUM_VALUE_LIST	NULL
 READ_ONLY	YES
 COMMAND_LINE_ARGUMENT	NULL
+select VARIABLE_NAME, GLOBAL_VALUE_ORIGIN, VARIABLE_SCOPE, VARIABLE_TYPE,
+VARIABLE_COMMENT, ENUM_VALUE_LIST, READ_ONLY, COMMAND_LINE_ARGUMENT
+from information_schema.system_variables
+where variable_name in (
+'log_tc_size'
+        )
+order by variable_name;
+VARIABLE_NAME	LOG_TC_SIZE
+GLOBAL_VALUE_ORIGIN	AUTO
+VARIABLE_SCOPE	GLOBAL
+VARIABLE_TYPE	BIGINT UNSIGNED
+VARIABLE_COMMENT	Size of transaction coordinator log.
+ENUM_VALUE_LIST	NULL
+READ_ONLY	YES
+COMMAND_LINE_ARGUMENT	REQUIRED
 set global div_precision_increment=default;

mysql-test/suite/sys_vars/t/log_tc_size_basic.test

+--error ER_INCORRECT_GLOBAL_LOCAL_VAR
+SET GLOBAL log_tc_size=1;
+
+--error ER_INCORRECT_GLOBAL_LOCAL_VAR
+SET SESSION log_tc_size=1;

mysql-test/t/mysqld--help.test

@@ -22,7 +22,7 @@ perl;
                log-slow-queries pid-file slow-query-log-file log-basename
                datadir slave-load-tmpdir tmpdir socket thread-pool-size
                large-files-support lower-case-file-system system-time-zone
-               version.*/;
+               log-tc-size version.*/;
 
   # Plugins which may or may not be there:
   @plugins=qw/innodb archive blackhole federated partition

sql/log.cc

@@ -8428,7 +8428,7 @@ ulong tc_log_page_waits= 0;
 
 static const uchar tc_log_magic[]={(uchar) 254, 0x23, 0x05, 0x74};
 
-ulong opt_tc_log_size= TC_LOG_MIN_SIZE;
+ulong opt_tc_log_size;
 ulong tc_log_max_pages_used=0, tc_log_page_size=0, tc_log_cur_pages_used=0;
 
 int TC_LOG_MMAP::open(const char *opt_name)
@@ -8441,7 +8441,6 @@ int TC_LOG_MMAP::open(const char *opt_name)
   DBUG_ASSERT(opt_name && opt_name[0]);
 
   tc_log_page_size= my_getpagesize();
-  DBUG_ASSERT(TC_LOG_PAGE_SIZE % tc_log_page_size == 0);
 
   fn_format(logname,opt_name,mysql_data_home,"",MY_UNPACK_FILENAME);
   if ((fd= mysql_file_open(key_file_tclog, logname, O_RDWR, MYF(0))) < 0)
@@ -8780,6 +8779,7 @@ mmap_do_checkpoint_callback(void *data)
 int TC_LOG_MMAP::unlog(ulong cookie, my_xid xid)
 {
   pending_cookies *full_buffer= NULL;
+  uint32 ncookies= tc_log_page_size / sizeof(my_xid);
   DBUG_ASSERT(*(my_xid *)(data+cookie) == xid);
 
   /*
@@ -8793,7 +8793,7 @@ int TC_LOG_MMAP::unlog(ulong cookie, my_xid xid)
   mysql_mutex_lock(&LOCK_pending_checkpoint);
   if (pending_checkpoint == NULL)
   {
-    uint32 size= sizeof(*pending_checkpoint);
+    uint32 size= sizeof(*pending_checkpoint) + sizeof(ulong) * (ncookies - 1);
     if (!(pending_checkpoint=
           (pending_cookies *)my_malloc(size, MYF(MY_ZEROFILL))))
     {
@@ -8804,8 +8804,7 @@ int TC_LOG_MMAP::unlog(ulong cookie, my_xid xid)
   }
 
   pending_checkpoint->cookies[pending_checkpoint->count++]= cookie;
-  if (pending_checkpoint->count == sizeof(pending_checkpoint->cookies) /
-      sizeof(pending_checkpoint->cookies[0]))
+  if (pending_checkpoint->count == ncookies)
   {
     full_buffer= pending_checkpoint;
     pending_checkpoint= NULL;
@@ -8839,7 +8838,7 @@ TC_LOG_MMAP::commit_checkpoint_notify(void *cookie)
   if (count == 0)
   {
     uint i;
-    for (i= 0; i < sizeof(pending->cookies)/sizeof(pending->cookies[0]); ++i)
+    for (i= 0; i < tc_log_page_size / sizeof(my_xid); ++i)
       delete_entry(pending->cookies[i]);
     my_free(pending);
   }

sql/log.h

@@ -118,7 +118,6 @@ public:
 };
 
 #define TC_LOG_PAGE_SIZE   8192
-#define TC_LOG_MIN_SIZE    (3*TC_LOG_PAGE_SIZE)
 
 #ifdef HAVE_MMAP
 class TC_LOG_MMAP: public TC_LOG
@@ -133,7 +132,7 @@ class TC_LOG_MMAP: public TC_LOG
   struct pending_cookies {
     uint count;
     uint pending_count;
-    ulong cookies[TC_LOG_PAGE_SIZE/sizeof(my_xid)];
+    ulong cookies[1];
   };
 
   private:

sql/mysqld.cc

@@ -4124,6 +4124,7 @@ static int init_common_variables()
   strmake(pidfile_name, opt_log_basename, sizeof(pidfile_name)-5);
   strmov(fn_ext(pidfile_name),".pid");		// Add proper extension
   SYSVAR_AUTOSIZE(pidfile_name_ptr, pidfile_name);
+  mark_sys_var_value_origin(&opt_tc_log_size, sys_var::AUTO);
 
   /*
     The default-storage-engine entry in my_long_options should have a
@@ -7224,12 +7225,6 @@ struct my_option my_long_options[]=
    "more than one storage engine, when binary log is disabled).",
    &opt_tc_log_file, &opt_tc_log_file, 0, GET_STR,
    REQUIRED_ARG, 0, 0, 0, 0, 0, 0},
-#ifdef HAVE_MMAP
-  {"log-tc-size", 0, "Size of transaction coordinator log.",
-   &opt_tc_log_size, &opt_tc_log_size, 0, GET_ULONG,
-   REQUIRED_ARG, TC_LOG_MIN_SIZE, TC_LOG_MIN_SIZE, (ulonglong) ULONG_MAX, 0,
-   TC_LOG_PAGE_SIZE, 0},
-#endif
   {"master-info-file", 0,
    "The location and name of the file that remembers the master and where "
    "the I/O replication thread is in the master's binlogs. Defaults to "

sql/sys_vars.cc

@@ -5202,3 +5202,14 @@ static Sys_var_mybool Sys_strict_password_validation(
        "that cannot be validated (passwords specified as a hash)",
        GLOBAL_VAR(strict_password_validation),
        CMD_LINE(OPT_ARG), DEFAULT(TRUE), NO_MUTEX_GUARD, NOT_IN_BINLOG);
+
+#ifdef HAVE_MMAP
+static Sys_var_ulong Sys_log_tc_size(
+       "log_tc_size",
+       "Size of transaction coordinator log.",
+       READ_ONLY GLOBAL_VAR(opt_tc_log_size),
+       CMD_LINE(REQUIRED_ARG),
+       VALID_RANGE(my_getpagesize() * 3, ULONG_MAX),
+       DEFAULT(my_getpagesize() * 6),
+       BLOCK_SIZE(my_getpagesize()));
+#endif