cleanup: Log_event::write() and MYSQL_BIN_LOG::write_cache()

Introduce Log_event_writer() that encapsulates
writing data to an IO_CACHE with automatic checksum calculation.

Now all events properly checksum themselves as needed.

Use Log_event_writer in MYSQL_BIN_LOG::write_cache() instead
of copy-pasting its logic all over.

Later Log_event_writer will also do encryption.

sql/log.h

@@ -737,6 +737,9 @@ public:
   void stop_union_events(THD *thd);
   bool is_query_in_union(THD *thd, query_id_t query_id_param);
 
+  bool write_event(Log_event *ev, IO_CACHE *file);
+  bool write_event(Log_event *ev) { return write_event(ev, &log_file); }
+
   /*
     v stands for vector
     invoked as appendv(buf1,len1,buf2,len2,...,bufn,lenn,0)

sql/log_event_old.cc

@@ -1753,7 +1753,7 @@ Old_rows_log_event::do_update_pos(rpl_group_info *rgi)
 
 
 #ifndef MYSQL_CLIENT
-bool Old_rows_log_event::write_data_header(IO_CACHE *file)
+bool Old_rows_log_event::write_data_header()
 {
   uchar buf[ROWS_HEADER_LEN];	// No need to init the buffer
 
@@ -1765,15 +1765,15 @@ bool Old_rows_log_event::write_data_header(IO_CACHE *file)
                   {
                     int4store(buf + 0, m_table_id);
                     int2store(buf + 4, m_flags);
-                    return (my_b_safe_write(file, buf, 6));
+                    return write_data(buf, 6);
                   });
   int6store(buf + RW_MAPID_OFFSET, (ulonglong)m_table_id);
   int2store(buf + RW_FLAGS_OFFSET, m_flags);
-  return (my_b_safe_write(file, buf, ROWS_HEADER_LEN));
+  return write_data(buf, ROWS_HEADER_LEN);
 }
 
 
-bool Old_rows_log_event::write_data_body(IO_CACHE*file)
+bool Old_rows_log_event::write_data_body()
 {
   /*
      Note that this should be the number of *bits*, not the number of
@@ -1790,13 +1790,12 @@ bool Old_rows_log_event::write_data_body(IO_CACHE*file)
   DBUG_ASSERT(static_cast<size_t>(sbuf_end - sbuf) <= sizeof(sbuf));
 
   DBUG_DUMP("m_width", sbuf, (size_t) (sbuf_end - sbuf));
-  res= res || my_b_safe_write(file, sbuf, (size_t) (sbuf_end - sbuf));
+  res= res || write_data(sbuf, (size_t) (sbuf_end - sbuf));
 
   DBUG_DUMP("m_cols", (uchar*) m_cols.bitmap, no_bytes_in_map(&m_cols));
-  res= res || my_b_safe_write(file, (uchar*) m_cols.bitmap,
-                              no_bytes_in_map(&m_cols));
+  res= res || write_data((uchar*)m_cols.bitmap, no_bytes_in_map(&m_cols));
   DBUG_DUMP("rows", m_rows_buf, data_size);
-  res= res || my_b_safe_write(file, m_rows_buf, (size_t) data_size);
+  res= res || write_data(m_rows_buf, (size_t) data_size);
 
   return res;
 

sql/log_event_old.h

@@ -134,8 +134,8 @@ public:
   ulong get_table_id() const        { return m_table_id; }
 
 #ifndef MYSQL_CLIENT
-  virtual bool write_data_header(IO_CACHE *file);
-  virtual bool write_data_body(IO_CACHE *file);
+  virtual bool write_data_header();
+  virtual bool write_data_body();
   virtual const char *get_db() { return m_table->s->db.str; }
 #endif
   /*

sql/slave.cc

@@ -5501,7 +5501,7 @@ static int queue_event(Master_info* mi,const char* buf, ulong event_len)
                           mi->master_log_name, rev.new_log_ident);
 
       mysql_mutex_lock(log_lock);
-      if (likely(!fdle.write(rli->relay_log.get_log_file()) &&
+      if (likely(!rli->relay_log.write_event(&fdle) &&
                  !rli->relay_log.flush_and_sync(NULL)))
       {
         rli->relay_log.harvest_bytes_written(&rli->log_space_total);

sql/wsrep_binlog.cc

@@ -445,6 +445,7 @@ void wsrep_dump_rbr_buf_with_header(THD *thd, const void *rbr_buf,
   char filename[PATH_MAX]= {0};
   File file;
   IO_CACHE cache;
+  Log_event_writer writer(&cache);
   Format_description_log_event *ev= wsrep_get_apply_format(thd);
 
   int len= my_snprintf(filename, PATH_MAX, "%s/GRA_%ld_%lld_v2.log",
@@ -476,7 +477,7 @@ void wsrep_dump_rbr_buf_with_header(THD *thd, const void *rbr_buf,
     goto cleanup2;
   }
 
-  if (ev->write(&cache) || my_b_write(&cache, (uchar*)rbr_buf, buf_len) ||
+  if (writer.write(ev) || my_b_write(&cache, (uchar*)rbr_buf, buf_len) ||
       flush_io_cache(&cache))
   {
     WSREP_ERROR("Failed to write to '%s'.", filename);

sql/wsrep_mysqld.cc

@@ -1215,6 +1215,7 @@ int wsrep_to_buf_helper(
     THD* thd, const char *query, uint query_len, uchar** buf, size_t* buf_len)
 {
   IO_CACHE tmp_io_cache;
+  Log_event_writer writer(&tmp_io_cache);
   if (open_cached_file(&tmp_io_cache, mysql_tmpdir, TEMP_PREFIX,
                        65536, MYF(MY_WME)))
     return 1;
@@ -1222,7 +1223,7 @@ int wsrep_to_buf_helper(
 
   Format_description_log_event *tmp_fd= new Format_description_log_event(4);
   tmp_fd->checksum_alg= (enum_binlog_checksum_alg)binlog_checksum_options;
-  tmp_fd->write(&tmp_io_cache);
+  writer.write(tmp_fd);
   delete tmp_fd;
 
 #ifdef GTID_SUPPORT
@@ -1230,7 +1231,7 @@ int wsrep_to_buf_helper(
   {
       Gtid_log_event gtid_ev(thd, FALSE, &thd->variables.gtid_next);
       if (!gtid_ev.is_valid()) ret= 0;
-      if (!ret && gtid_ev.write(&tmp_io_cache)) ret= 1;
+      if (!ret && writer.write(&gtid_ev)) ret= 1;
   }
 #endif /* GTID_SUPPORT */
 
@@ -1240,12 +1241,12 @@ int wsrep_to_buf_helper(
     Query_log_event ev(thd, thd->wsrep_TOI_pre_query,
 		       thd->wsrep_TOI_pre_query_len,
 		       FALSE, FALSE, FALSE, 0);
-    if (ev.write(&tmp_io_cache)) ret= 1;
+    if (writer.write(&ev)) ret= 1;
   }
 
   /* continue to append the actual query */
   Query_log_event ev(thd, query, query_len, FALSE, FALSE, FALSE, 0);
-  if (!ret && ev.write(&tmp_io_cache)) ret= 1;
+  if (!ret && writer.write(&ev)) ret= 1;
   if (!ret && wsrep_write_cache_buf(&tmp_io_cache, buf, buf_len)) ret= 1;
   close_cached_file(&tmp_io_cache);
   return ret;