Start with Tree

src/main/java/com/tomfran/lsm/memtable/Memtable.java

@@ -5,21 +5,24 @@
 
 public class Memtable {
 
-    static final int DEFAULT_SAMPLE_SIZE = 1000;
+    static final int DEFAULT_SSTABLE_SAMPLE_SIZE = 1 << 10;
 
     SkipList list;
 
-
     public Memtable() {
         list = new SkipList();
     }
 
+    public Memtable(int numElements) {
+        list = new SkipList(numElements);
+    }
+
     public void add(Item item) {
         list.add(item);
     }
 
-    public void get(byte[] key) {
-        list.get(key);
+    public Item get(byte[] key) {
+        return list.get(key);
     }
 
     public void remove(byte[] key) {
@@ -30,9 +33,8 @@ public int size() {
         return list.size();
     }
 
-    public SSTable flush() {
-        String filename = "sstable-" + System.currentTimeMillis();
-        return new SSTable(filename, list, DEFAULT_SAMPLE_SIZE, list.size());
+    public SSTable flush(String filename) {
+        return new SSTable(filename, list, DEFAULT_SSTABLE_SAMPLE_SIZE, list.size());
     }
 
 }

src/main/java/com/tomfran/lsm/tree/LSMTree.java

@@ -0,0 +1,56 @@
+package com.tomfran.lsm.tree;
+
+import com.tomfran.lsm.memtable.Memtable;
+import com.tomfran.lsm.sstable.SSTable;
+import com.tomfran.lsm.types.Item;
+
+import java.util.LinkedList;
+
+public class LSMTree {
+
+    static final int MEMTABLE_MAX_SIZE = 1 << 16;
+
+    Memtable mutableMemtable;
+    LinkedList<Memtable> immutableMemtables;
+    LinkedList<SSTable> tables;
+
+    public LSMTree() {
+        mutableMemtable = new Memtable(MEMTABLE_MAX_SIZE);
+        immutableMemtables = new LinkedList<>();
+        tables = new LinkedList<>();
+    }
+
+    public void add(Item item) {
+        mutableMemtable.add(item);
+        checkMemtableSize();
+    }
+
+    public void delete(byte[] key) {
+        mutableMemtable.remove(key);
+        checkMemtableSize();
+    }
+
+    private void checkMemtableSize() {
+        if (mutableMemtable.size() >= MEMTABLE_MAX_SIZE) {
+            immutableMemtables.add(mutableMemtable);
+            mutableMemtable = new Memtable(MEMTABLE_MAX_SIZE);
+        }
+    }
+
+    public Item get(byte[] key) {
+        Item result;
+
+        if ((result = mutableMemtable.get(key)) != null)
+            return result;
+
+        for (Memtable memtable : immutableMemtables)
+            if ((result = memtable.get(key)) != null)
+                return result;
+
+        for (SSTable table : tables)
+            if ((result = table.get(key)) != null)
+                return result;
+
+        return null;
+    }
+}