(feat) Export RocksDB options to users #20

jraft-core/src/main/java/com/alipay/sofa/jraft/util/StorageOptionsFactory.java

@@ -92,21 +92,18 @@ public static ColumnFamilyOptions getDefaultRocksDBColumnFamilyOptions() {
         final ColumnFamilyOptions opts = new ColumnFamilyOptions();
 
         // Flushing options:
-        //
         // write_buffer_size sets the size of a single mem_table. Once mem_table exceeds
         // this size, it is marked immutable and a new one is created.
         opts.setWriteBufferSize(64 * SizeUnit.MB);
 
         // Flushing options:
-        //
         // max_write_buffer_number sets the maximum number of mem_tables, both active
         // and immutable.  If the active mem_table fills up and the total number of
         // mem_tables is larger than max_write_buffer_number we stall further writes.
         // This may happen if the flush process is slower than the write rate.
         opts.setMaxWriteBufferNumber(3);
 
         // Flushing options:
-        //
         // min_write_buffer_number_to_merge is the minimum number of mem_tables to be
         // merged before flushing to storage. For example, if this option is set to 2,
         // immutable mem_tables are only flushed when there are two of them - a single