From a409cdbd8e92b7ecf5c260a873d3744dbe06a4a4 Mon Sep 17 00:00:00 2001
From: Azrenbeth <77782548+Azrenbeth@users.noreply.github.com>
Date: Tue, 14 Sep 2021 12:28:35 +0100
Subject: [PATCH] Rename level current to head (#61)

---
 src/compressor.rs                  | 31 +++++++++++++++++++-----------
 src/compressor/compressor_tests.rs |  4 ++--
 src/compressor/level_tests.rs      | 12 ++++++------
 src/database.rs                    |  5 +----
 4 files changed, 29 insertions(+), 23 deletions(-)

diff --git a/src/compressor.rs b/src/compressor.rs
index 26bacd2..c4eb892 100644
--- a/src/compressor.rs
+++ b/src/compressor.rs
@@ -44,7 +44,7 @@ pub struct Level {
     /// to recursively following `current`
     current_chain_length: usize,
     /// The head of this level
-    current: Option<i64>,
+    head: Option<i64>,
 }
 
 impl Level {
@@ -53,16 +53,16 @@ impl Level {
         Level {
             max_length,
             current_chain_length: 0,
-            current: None,
+            head: None,
         }
     }
 
     /// Creates a new level from stored state
-    pub fn restore(max_length: usize, current_chain_length: usize, current: Option<i64>) -> Level {
+    pub fn restore(max_length: usize, current_chain_length: usize, head: Option<i64>) -> Level {
         Level {
             max_length,
             current_chain_length,
-            current,
+            head,
         }
     }
 
@@ -70,8 +70,8 @@ impl Level {
     /// that given state group will (probably) reference the previous head.
     ///
     /// Panics if `delta` is true and the level is already full.
-    fn update(&mut self, current: i64, delta: bool) {
-        self.current = Some(current);
+    fn update(&mut self, new_head: i64, delta: bool) {
+        self.head = Some(new_head);
 
         if delta {
             // If we're referencing the previous head then increment our chain
@@ -87,9 +87,19 @@ impl Level {
         }
     }
 
+    /// Get the max length of the level
+    pub fn get_max_length(&self) -> usize {
+        self.max_length
+    }
+
+    /// Get the current length of the level
+    pub fn get_current_length(&self) -> usize {
+        self.current_chain_length
+    }
+
     /// Get the current head of the level
-    pub fn get_current(&self) -> Option<i64> {
-        self.current
+    pub fn get_head(&self) -> Option<i64> {
+        self.head
     }
 
     /// Whether there is space in the current chain at this level. If not then a
@@ -142,12 +152,11 @@ impl<'a> Compressor<'a> {
     /// in which case the levels heads are also known
     pub fn compress_from_save(
         original_state_map: &'a BTreeMap<i64, StateGroupEntry>,
-        // level_info: &[(usize, usize, Option<i64>)],
         level_info: &[Level],
     ) -> Compressor<'a> {
         let levels = level_info
             .iter()
-            .map(|l| Level::restore((*l).max_length, (*l).current_chain_length, (*l).current))
+            .map(|l| Level::restore((*l).max_length, (*l).current_chain_length, (*l).head))
             .collect();
 
         let mut compressor = Compressor {
@@ -200,7 +209,7 @@ impl<'a> Compressor<'a> {
             let mut prev_state_group = None;
             for level in &mut self.levels {
                 if level.has_space() {
-                    prev_state_group = level.get_current();
+                    prev_state_group = level.get_head();
                     level.update(state_group, true);
                     break;
                 } else {
diff --git a/src/compressor/compressor_tests.rs b/src/compressor/compressor_tests.rs
index a511920..de64189 100644
--- a/src/compressor/compressor_tests.rs
+++ b/src/compressor/compressor_tests.rs
@@ -677,11 +677,11 @@ fn get_delta_returns_snapshot_if_no_prev_possible() {
     let mut levels_iter = compressor.levels.iter_mut();
 
     let l1 = levels_iter.next().unwrap();
-    l1.current = Some(3);
+    l1.head = Some(3);
     l1.current_chain_length = 1;
 
     let l2 = levels_iter.next().unwrap();
-    l2.current = Some(3);
+    l2.head = Some(3);
     l2.current_chain_length = 1;
 
     // Now try and find delta for 4 with 3 as pred
diff --git a/src/compressor/level_tests.rs b/src/compressor/level_tests.rs
index f57ef1d..b058b81 100644
--- a/src/compressor/level_tests.rs
+++ b/src/compressor/level_tests.rs
@@ -5,7 +5,7 @@ fn new_produces_empty_level() {
     let l = Level::new(15);
     assert_eq!(l.max_length, 15);
     assert_eq!(l.current_chain_length, 0);
-    assert_eq!(l.current, None);
+    assert_eq!(l.head, None);
 }
 
 #[test]
@@ -14,7 +14,7 @@ fn update_adds_to_non_full_level() {
     l.update(7, true);
     assert_eq!(l.max_length, 10);
     assert_eq!(l.current_chain_length, 1);
-    assert_eq!(l.current, Some(7));
+    assert_eq!(l.head, Some(7));
 }
 
 #[test]
@@ -40,15 +40,15 @@ fn update_resets_level_correctly() {
     l.update(6, false);
     assert_eq!(l.max_length, 5);
     assert_eq!(l.current_chain_length, 1);
-    assert_eq!(l.current, Some(6));
+    assert_eq!(l.head, Some(6));
 }
 
 #[test]
-fn get_current_returns_current() {
+fn get_head_returns_head() {
     let mut l = Level::new(5);
-    assert_eq!(l.get_current(), None);
+    assert_eq!(l.get_head(), None);
     l.update(23, true);
-    assert_eq!(l.get_current(), Some(23));
+    assert_eq!(l.get_head(), Some(23));
 }
 
 #[test]
diff --git a/src/database.rs b/src/database.rs
index bb0da27..03b9301 100644
--- a/src/database.rs
+++ b/src/database.rs
@@ -126,10 +126,7 @@ pub fn reload_data_from_db(
 /// * `levels'  -   The levels who's heads are being requested
 fn load_level_heads(client: &mut Client, level_info: &[Level]) -> BTreeMap<i64, StateGroupEntry> {
     // obtain all of the heads that aren't None from level_info
-    let level_heads: Vec<i64> = level_info
-        .iter()
-        .filter_map(|l| (*l).get_current())
-        .collect();
+    let level_heads: Vec<i64> = level_info.iter().filter_map(|l| (*l).get_head()).collect();
 
     // Query to get id, predecessor and deltas for each state group
     let sql = r#"