Feature: LogIdList: add method purge() to delete log ids

openraft/src/engine/log_id_list.rs

@@ -80,6 +80,34 @@ impl<NID: NodeId> LogIdList<NID> {
         self.key_log_ids.push(new_log_id);
     }
 
+    /// Purge log ids upto the log with index `upto_index`, inclusive.
+    #[allow(dead_code)]
+    pub(crate) fn purge(&mut self, upto: &LogId<NID>) {
+        // When installing  snapshot it may need to purge across the `last_log_id`.
+        if upto.index > self.key_log_ids[self.key_log_ids.len() - 1].index {
+            assert!(upto > &self.key_log_ids[self.key_log_ids.len() - 1]);
+            self.key_log_ids = vec![*upto];
+        }
+
+        if upto.index < self.key_log_ids[0].index {
+            return;
+        }
+
+        let res = self.key_log_ids.binary_search_by(|log_id| log_id.index.cmp(&upto.index));
+
+        match res {
+            Ok(i) => {
+                if i > 0 {
+                    self.key_log_ids = self.key_log_ids.split_off(i)
+                }
+            }
+            Err(i) => {
+                self.key_log_ids = self.key_log_ids.split_off(i - 1);
+                self.key_log_ids[0].index = upto.index;
+            }
+        }
+    }
+
     /// Get the log id at the specified index.
     ///
     /// It will return `last_purged_log_id` if index is at the last purged index.

openraft/src/engine/log_id_list_test.rs

@@ -4,11 +4,6 @@ use crate::LogId;
 
 #[test]
 fn test_log_id_list_extend_from_same_leader() -> anyhow::Result<()> {
-    let log_id = |t, i| LogId::<u64> {
-        leader_id: LeaderId { term: t, node_id: 1 },
-        index: i,
-    };
-
     let mut ids = LogIdList::<u64>::default();
 
     // Extend one log id to an empty LogIdList: Just store it directly
@@ -55,11 +50,6 @@ fn test_log_id_list_extend_from_same_leader() -> anyhow::Result<()> {
 
 #[test]
 fn test_log_id_list_append() -> anyhow::Result<()> {
-    let log_id = |t, i| LogId::<u64> {
-        leader_id: LeaderId { term: t, node_id: 1 },
-        index: i,
-    };
-
     let mut ids = LogIdList::<u64>::default();
 
     // Append log id one by one, check the internally constructed `key_log_id` as expected.
@@ -82,12 +72,71 @@ fn test_log_id_list_append() -> anyhow::Result<()> {
 }
 
 #[test]
-fn test_log_id_list_get_log_id() -> anyhow::Result<()> {
-    let log_id = |t, i| LogId::<u64> {
-        leader_id: LeaderId { term: t, node_id: 1 },
-        index: i,
-    };
+fn test_log_id_list_purge() -> anyhow::Result<()> {
+    // Append log id one by one, check the internally constructed `key_log_id` as expected.
+
+    let cases = vec![
+        //
+        (log_id(2, 1), vec![
+            log_id(2, 2),
+            log_id(3, 3),
+            log_id(6, 6),
+            log_id(9, 9),
+            log_id(9, 11),
+        ]),
+        (log_id(2, 2), vec![
+            log_id(2, 2),
+            log_id(3, 3),
+            log_id(6, 6),
+            log_id(9, 9),
+            log_id(9, 11),
+        ]),
+        (log_id(3, 3), vec![
+            log_id(3, 3),
+            log_id(6, 6),
+            log_id(9, 9),
+            log_id(9, 11),
+        ]),
+        (log_id(3, 4), vec![
+            log_id(3, 4),
+            log_id(6, 6),
+            log_id(9, 9),
+            log_id(9, 11),
+        ]),
+        (log_id(3, 5), vec![
+            log_id(3, 5),
+            log_id(6, 6),
+            log_id(9, 9),
+            log_id(9, 11),
+        ]),
+        (log_id(6, 6), vec![log_id(6, 6), log_id(9, 9), log_id(9, 11)]),
+        (log_id(6, 7), vec![log_id(6, 7), log_id(9, 9), log_id(9, 11)]),
+        (log_id(6, 8), vec![log_id(6, 8), log_id(9, 9), log_id(9, 11)]),
+        (log_id(9, 9), vec![log_id(9, 9), log_id(9, 11)]),
+        (log_id(9, 10), vec![log_id(9, 10), log_id(9, 11)]),
+        (log_id(9, 11), vec![log_id(9, 11)]),
+        (log_id(9, 12), vec![log_id(9, 12)]),
+        (log_id(10, 12), vec![log_id(10, 12)]),
+    ];
+
+    for (upto, want) in cases {
+        let mut ids = LogIdList::<u64>::new(vec![
+            log_id(2, 2), // force multi line
+            log_id(3, 3),
+            log_id(6, 6),
+            log_id(9, 9),
+            log_id(9, 11),
+        ]);
+
+        ids.purge(&upto);
+        assert_eq!(want, ids.key_log_ids(), "purge upto: {}", upto);
+    }
+
+    Ok(())
+}
 
+#[test]
+fn test_log_id_list_get_log_id() -> anyhow::Result<()> {
     // Get log id from empty list always returns `None`.
 
     let ids = LogIdList::<u64>::default();
@@ -122,3 +171,9 @@ fn test_log_id_list_get_log_id() -> anyhow::Result<()> {
 
     Ok(())
 }
+fn log_id(term: u64, index: u64) -> LogId<u64> {
+    LogId::<u64> {
+        leader_id: LeaderId { term, node_id: 1 },
+        index,
+    }
+}