cleanup: Log_event::read_log_event()

There are three Log_event::read_log_event() methods:
1. read the event image from IO_CACHE into String
2. create Log_event from the in-memory event image
3. read the event image from IO_CACHE and create Log_event

The 3rd was reading event image into memory and invoking the 2nd to
create Log_event. Now the 3rd also uses the 1st to read the event image
from IO_CACHE into memory, instead of duplicating its functionality.

client/mysqlbinlog.cc

@@ -2240,7 +2240,7 @@ static Exit_status check_header(IO_CACHE* file,
         Format_description_log_event *new_description_event;
         my_b_seek(file, tmp_pos); /* seek back to event's start */
         if (!(new_description_event= (Format_description_log_event*) 
-              Log_event::read_log_event(file, glob_description_event,
+              Log_event::read_log_event(file, 0, glob_description_event,
                                         opt_verify_binlog_checksum)))
           /* EOF can't be hit here normally, so it's a real error */
         {
@@ -2274,7 +2274,7 @@ static Exit_status check_header(IO_CACHE* file,
       {
         Log_event *ev;
         my_b_seek(file, tmp_pos); /* seek back to event's start */
-        if (!(ev= Log_event::read_log_event(file, glob_description_event,
+        if (!(ev= Log_event::read_log_event(file, 0, glob_description_event,
                                             opt_verify_binlog_checksum)))
         {
           /* EOF can't be hit here normally, so it's a real error */
@@ -2388,7 +2388,7 @@ static Exit_status dump_local_log_entries(PRINT_EVENT_INFO *print_event_info,
     char llbuff[21];
     my_off_t old_off = my_b_tell(file);
 
-    Log_event* ev = Log_event::read_log_event(file, glob_description_event,
+    Log_event* ev = Log_event::read_log_event(file, 0, glob_description_event,
                                               opt_verify_binlog_checksum);
     if (!ev)
     {

sql/log_event.h

@@ -1127,6 +1127,39 @@ class Log_event
 
   Log_event();
   Log_event(THD* thd_arg, uint16 flags_arg, bool is_transactional);
+
+  /*
+    init_show_field_list() prepares the column names and types for the
+    output of SHOW BINLOG EVENTS; it is used only by SHOW BINLOG
+    EVENTS.
+  */
+  static void init_show_field_list(THD *thd, List<Item>* field_list);
+#ifdef HAVE_REPLICATION
+  int net_send(THD *thd, Protocol *protocol, const char* log_name,
+               my_off_t pos);
+
+  /*
+    pack_info() is used by SHOW BINLOG EVENTS; as print() it prepares and sends
+    a string to display to the user, so it resembles print().
+  */
+
+  virtual void pack_info(THD *thd, Protocol *protocol);
+
+#endif /* HAVE_REPLICATION */
+  virtual const char* get_db()
+  {
+    return thd ? thd->db : 0;
+  }
+#else
+  Log_event() : temp_buf(0), flags(0) {}
+  /* print*() functions are used by mysqlbinlog */
+  virtual void print(FILE* file, PRINT_EVENT_INFO* print_event_info) = 0;
+  void print_timestamp(IO_CACHE* file, time_t *ts = 0);
+  void print_header(IO_CACHE* file, PRINT_EVENT_INFO* print_event_info,
+                    bool is_more);
+  void print_base64(IO_CACHE* file, PRINT_EVENT_INFO* print_event_info,
+                    bool is_more);
+#endif
   /*
     read_log_event() functions read an event from a binlog or relay
     log; used by SHOW BINLOG EVENTS, the binlog_dump thread on the
@@ -1155,9 +1188,9 @@ class Log_event
 
     @param[in]  file                log file to be read
     @param[out] packet              packet to hold the event
-    @param[in]  lock                the lock to be used upon read
-    @param[in]  log_file_name_arg   the log's file name
-    @param[out] is_binlog_active    is the current log still active
+    @param[in]  checksum_alg_arg    verify the event checksum using this
+                                    algorithm (or don't if it's
+                                    use BINLOG_CHECKSUM_ALG_OFF)
 
     @retval 0                   success
     @retval LOG_READ_EOF        end of file, nothing was read
@@ -1168,46 +1201,7 @@ class Log_event
     @retval LOG_READ_TOO_LARGE  event too large
    */
   static int read_log_event(IO_CACHE* file, String* packet,
-                            mysql_mutex_t* log_lock,
-                            uint8 checksum_alg_arg,
-                            const char *log_file_name_arg = NULL,
-                            bool* is_binlog_active = NULL);
-  /*
-    init_show_field_list() prepares the column names and types for the
-    output of SHOW BINLOG EVENTS; it is used only by SHOW BINLOG
-    EVENTS.
-  */
-  static void init_show_field_list(THD *thd, List<Item>* field_list);
-#ifdef HAVE_REPLICATION
-  int net_send(THD *thd, Protocol *protocol, const char* log_name,
-               my_off_t pos);
-
-  /*
-    pack_info() is used by SHOW BINLOG EVENTS; as print() it prepares and sends
-    a string to display to the user, so it resembles print().
-  */
-
-  virtual void pack_info(THD *thd, Protocol *protocol);
-
-#endif /* HAVE_REPLICATION */
-  virtual const char* get_db()
-  {
-    return thd ? thd->db : 0;
-  }
-#else
-  Log_event() : temp_buf(0), flags(0) {}
-    /* avoid having to link mysqlbinlog against libpthread */
-  static Log_event* read_log_event(IO_CACHE* file,
-                                   const Format_description_log_event
-                                   *description_event, my_bool crc_check);
-  /* print*() functions are used by mysqlbinlog */
-  virtual void print(FILE* file, PRINT_EVENT_INFO* print_event_info) = 0;
-  void print_timestamp(IO_CACHE* file, time_t *ts = 0);
-  void print_header(IO_CACHE* file, PRINT_EVENT_INFO* print_event_info,
-                    bool is_more);
-  void print_base64(IO_CACHE* file, PRINT_EVENT_INFO* print_event_info,
-                    bool is_more);
-#endif
+                            uint8 checksum_alg_arg);
   /* 
      The value is set by caller of FD constructor and
      Log_event::write_header() for the rest.

sql/rpl_utility.cc

@@ -1200,9 +1200,9 @@ bool event_checksum_test(uchar *event_buf, ulong event_len, uint8 alg)
       DBUG_ASSERT(event_buf[EVENT_TYPE_OFFSET] == FORMAT_DESCRIPTION_EVENT);
       event_buf[FLAGS_OFFSET]= (uchar) flags;
     }
-    res= !(computed == incoming);
+    res= DBUG_EVALUATE_IF("simulate_checksum_test_failure", TRUE, computed != incoming);
   }
-  return DBUG_EVALUATE_IF("simulate_checksum_test_failure", TRUE, res);
+  return res;
 }
 
 #if defined(MYSQL_SERVER) && defined(HAVE_REPLICATION)

sql/sql_repl.cc

@@ -1436,8 +1436,9 @@ gtid_state_from_pos(const char *name, uint32 offset,
       break;
 
     packet.length(0);
-    err= Log_event::read_log_event(&cache, &packet, NULL,
-                                   current_checksum_alg);
+    err= Log_event::read_log_event(&cache, &packet,
+                                   opt_master_verify_checksum
+                                   ? current_checksum_alg : 0);
     if (err)
     {
       errormsg= "Could not read binlog while searching for slave start "
@@ -2230,8 +2231,9 @@ static int send_format_descriptor_event(binlog_send_info *info,
       the binlog
     */
     info->last_pos= my_b_tell(log);
-    error= Log_event::read_log_event(log, packet, /* LOCK_log */ NULL,
-                                     info->current_checksum_alg);
+    error= Log_event::read_log_event(log, packet,
+                                     opt_master_verify_checksum
+                                     ? info->current_checksum_alg : 0);
     linfo->pos= my_b_tell(log);
 
     if (error)
@@ -2566,9 +2568,9 @@ static int send_events(binlog_send_info *info,
       return 1;
 
     info->last_pos= linfo->pos;
-    error = Log_event::read_log_event(log, packet, /* LOCK_log */ NULL,
-                                      info->current_checksum_alg,
-                                      NULL, NULL);
+    error= Log_event::read_log_event(log, packet,
+                                     opt_master_verify_checksum
+                                     ? info->current_checksum_alg : 0);
     linfo->pos= my_b_tell(log);
 
     if (error)