feat(code): part 3 iterators

Signed-off-by: Alex Chi <iskyzh@gmail.com>

mini-lsm-starter/src/table/builder.rs

@@ -1,9 +1,10 @@
 #![allow(unused_variables)] // TODO(you): remove this lint after implementing this mod
 #![allow(dead_code)] // TODO(you): remove this lint after implementing this mod
 
-use anyhow::Result;
 use std::path::Path;
 
+use anyhow::Result;
+
 use super::{BlockMeta, SsTable};
 
 /// Builds an SSTable from key-value pairs.
@@ -14,17 +15,22 @@ pub struct SsTableBuilder {
 
 impl SsTableBuilder {
     /// Create a builder based on target SST size and target block size.
-    pub fn new(target_size: usize, block_size: usize) -> Self {
+    pub fn new(block_size: usize) -> Self {
         unimplemented!()
     }
 
-    /// Adds a key-value pair to SSTable, return false when SST full.
-    #[must_use]
-    pub fn add(&mut self, key: &[u8], value: &[u8]) -> bool {
+    /// Adds a key-value pair to SSTable
+    pub fn add(&mut self, key: &[u8], value: &[u8]) {
         unimplemented!()
     }
 
-    /// Builds the SSTable and writes it to the given path. No need to actually write to disk until chapter 4 block cache.
+    /// Get the estimated size of the SSTable.
+    pub fn estimated_size(&self) -> usize {
+        unimplemented!()
+    }
+
+    /// Builds the SSTable and writes it to the given path. No need to actually write to disk until
+    /// chapter 4 block cache.
     pub fn build(self, path: impl AsRef<Path>) -> Result<SsTable> {
         unimplemented!()
     }