fix: put memtable resizing behind genserver

lib/august_db/commitlog.ex

@@ -16,14 +16,14 @@ defmodule CommitLog do
     {:ok, device_out}
   end
 
-  def handle_cast(:new, _) do
+  def handle_cast(:new, old_device_out) do
+    :ok = :file.close(old_device_out)
     :ok = :file.delete(@log_file)
-    {:ok, device_out} = :file.open(@log_file, [:append])
-    {:noreply, device_out}
+    {:ok, new_device_out} = :file.open(@log_file, [:append, :raw])
+    {:noreply, new_device_out}
   end
 
   def handle_cast(:close, device_out) do
-    :ok = :file.close(device_out)
     {:noreply, device_out}
   end
 
@@ -96,8 +96,11 @@ defmodule CommitLog do
     File.touch!(@log_file)
   end
 
+  @doc """
+  Delete the old commit log and open a device  to a new one
+  in raw,append mode.
+  """
   def new() do
-    GenServer.cast(CommitLogDevice, :close)
     GenServer.cast(CommitLogDevice, :new)
   end
 end

lib/august_db/memtable_sizer.ex

@@ -1,7 +1,7 @@
 defmodule Memtable.Sizer do
   use GenServer
 
-  @max_size_bytes 64 * 1024 * 1024
+  @max_size_bytes 1024 * 1024
 
   defmodule State do
     defstruct total_size: 0, sizes: %{}
@@ -15,7 +15,7 @@ defmodule Memtable.Sizer do
     {:ok, state}
   end
 
-  def handle_call({:resize, key, kv_size}, _from, state) do
+  def handle_cast({:resize, key, kv_size}, state) do
     old_kv_size =
       case Map.get(state.sizes, key) do
         nil -> 0
@@ -26,8 +26,14 @@ defmodule Memtable.Sizer do
 
     new_total_size = state.total_size + kv_size_diff
 
-    {:reply, new_total_size,
-     %State{total_size: new_total_size, sizes: Map.put(state.sizes, key, kv_size)}}
+    if new_total_size > @max_size_bytes do
+      IO.puts("Clearing Memtable with size #{new_total_size}B, max is #{@max_size_bytes}B")
+
+      Memtable.flush()
+      {:noreply, %State{total_size: 9, sizes: %{}}}
+    else
+      {:noreply, %State{total_size: new_total_size, sizes: Map.put(state.sizes, key, kv_size)}}
+    end
   end
 
   def handle_cast(:clear, _state) do
@@ -37,25 +43,10 @@ defmodule Memtable.Sizer do
   def resize(key, value) when is_binary(key) and is_binary(value) do
     kv_size = byte_size(key) + byte_size(value)
 
-    update(key, kv_size)
+    GenServer.cast(MemtableSizer, {:resize, key, kv_size})
   end
 
   def remove(key) when is_binary(key) do
-    update(key, byte_size(key))
-  end
-
-  defp update(key, kv_size) do
-    new_total_size = GenServer.call(MemtableSizer, {:resize, key, kv_size})
-
-    if new_total_size > @max_size_bytes do
-      IO.puts("Clearing Memtable with size #{new_total_size}B, max is #{@max_size_bytes}B")
-
-      Memtable.flush()
-      __MODULE__.clear()
-    end
-  end
-
-  def clear() do
-    GenServer.cast(MemtableSizer, :clear)
+    GenServer.cast(MemtableSizer, {:resize, key, byte_size(key)})
   end
 end

test/AugustDB.jmx

@@ -20,7 +20,7 @@
           <stringProp name="LoopController.loops">200</stringProp>
         </elementProp>
         <stringProp name="ThreadGroup.num_threads">500</stringProp>
-        <stringProp name="ThreadGroup.ramp_time">1</stringProp>
+        <stringProp name="ThreadGroup.ramp_time">5</stringProp>
         <boolProp name="ThreadGroup.scheduler">false</boolProp>
         <stringProp name="ThreadGroup.duration"></stringProp>
         <stringProp name="ThreadGroup.delay"></stringProp>
@@ -42,7 +42,7 @@
         </ConfigTestElement>
         <hashTree/>
         <RandomVariableConfig guiclass="TestBeanGUI" testclass="RandomVariableConfig" testname="Random Key" enabled="true">
-          <stringProp name="maximumValue">4294967295</stringProp>
+          <stringProp name="maximumValue">2147483647</stringProp>
           <stringProp name="minimumValue">1</stringProp>
           <stringProp name="outputFormat"></stringProp>
           <boolProp name="perThread">true</boolProp>