1 files changed, 40 insertions, 0 deletions
diff --git a/autere_db/src/memtable_primary.rs b/autere_db/src/memtable_primary.rs
new file mode 100644
index 0000000..573592e
--- /dev/null
+++ b/autere_db/src/memtable_primary.rs
@@ -0,0 +1,40 @@
+use super::*;
+use std::collections::BTreeMap;
+
+pub struct PrimaryMemtable {
+    /// Map of records indexed by key. Used as a shared heap of records
+    /// for all secondary memtables also. Secondary memtables store an
+    /// IndexableValue as their record value, which is used to get
+    /// the actual record from the primary memtable `records` map.
+    ///
+    /// Note: it must be invariant that all memtables (primary and secondary)
+    /// contain the same keys.
+    records: BTreeMap<IndexableValue, LogKey>,
+}
+
+impl PrimaryMemtable {
+    pub fn new() -> PrimaryMemtable {
+        PrimaryMemtable {
+            records: BTreeMap::new(),
+        }
+    }
+
+    pub fn set(&mut self, key: IndexableValue, value: LogKey) {
+        self.records.insert(key, value);
+    }
+
+    pub fn get(&self, key: &IndexableValue) -> Option<&LogKey> {
+        self.records.get(key)
+    }
+
+    pub fn remove(&mut self, key: &IndexableValue) -> Option<LogKey> {
+        self.records.remove(key)
+    }
+
+    pub fn range<B: RangeBounds<IndexableValue>>(&self, range: B) -> Vec<&LogKey> {
+        self.records
+            .range(range)
+            .map(|(_, log_key)| log_key)
+            .collect()
+    }
+}