Initial head_only features

Initial commit to add head_only mode to leveled.  This allows leveled to receive batches of object changes, but where those objects exist only in the Penciller's Ledger (once they have been persisted within the Ledger).

The aim is to reduce significantly the cost of compaction.  Also, the objects ar enot directly accessible (they can only be accessed through folds).  Again this makes life easier during merging in the LSM trees (as no bloom filters have to be created).

src/leveled_inker.erl

@@ -95,6 +95,7 @@
         code_change/3,
         ink_start/1,
         ink_put/4,
+        ink_mput/3,
         ink_get/3,
         ink_fetch/3,
         ink_keycheck/3,
@@ -105,6 +106,7 @@
         ink_compactjournal/3,
         ink_compactioncomplete/1,
         ink_compactionpending/1,
+        ink_trim/2,
         ink_getmanifest/1,
         ink_updatemanifest/3,
         ink_printmanifest/1,
@@ -185,6 +187,16 @@ ink_start(InkerOpts) ->
 ink_put(Pid, PrimaryKey, Object, KeyChanges) ->
     gen_server:call(Pid, {put, PrimaryKey, Object, KeyChanges}, infinity).
 
+
+-spec ink_mput(pid(), any(), {list(), integer()|infinity}) -> {ok, integer()}.
+%% @doc
+%% MPUT as series of object specifications, which will be converted into 
+%% objects in the Ledger.  This should only be used when the Bookie is 
+%% running in head_only mode.  The journal entries arekept only for handling
+%% consistency on startup
+ink_mput(Pid, PrimaryKey, ObjectChanges) ->
+    gen_server:call(Pid, {mput, PrimaryKey, ObjectChanges}, infinity).
+
 -spec ink_get(pid(),
                 {atom(), any(), any(), any()}|string(),
                 integer()) ->
@@ -361,10 +373,17 @@ ink_compactioncomplete(Pid) ->
 -spec ink_compactionpending(pid()) -> boolean().
 %% @doc
 %% Is there ongoing compaction work?  No compaction work should be initiated
-%5 if there is already some compaction work ongoing.
+%% if there is already some compaction work ongoing.
 ink_compactionpending(Pid) ->
     gen_server:call(Pid, compaction_pending, infinity).
 
+-spec ink_trim(pid(), integer()) -> ok.
+%% @doc
+%% Trim the Journal to just those files that contain entries since the 
+%% Penciller's persisted SQN
+ink_trim(Pid, PersistedSQN) ->
+    gen_server:call(Pid, {trim, PersistedSQN}, infinity).
+
 -spec ink_getmanifest(pid()) -> list().
 %% @doc
 %% Allows the clerk to fetch the manifest at the point it starts a compaction
@@ -420,6 +439,11 @@ handle_call({put, Key, Object, KeyChanges}, _From, State) ->
         {_, UpdState, ObjSize} ->
             {reply, {ok, UpdState#state.journal_sqn, ObjSize}, UpdState}
     end;
+handle_call({mput, Key, ObjChanges}, _From, State) ->
+    case put_object(Key, head_only, ObjChanges, State) of
+        {_, UpdState, _ObjSize} ->
+            {reply, {ok, UpdState#state.journal_sqn}, UpdState}
+    end;
 handle_call({fetch, Key, SQN}, _From, State) ->
     case get_object(Key, SQN, State#state.manifest, true) of
         {{SQN, Key}, {Value, _IndexSpecs}} ->
@@ -503,6 +527,9 @@ handle_call(compaction_complete, _From, State) ->
     {reply, ok, State#state{compaction_pending=false}};
 handle_call(compaction_pending, _From, State) ->
     {reply, State#state.compaction_pending, State};
+handle_call({trim, PersistedSQN}, _From, State) ->
+    ok = leveled_iclerk:clerk_trim(State#state.clerk, self(), PersistedSQN),
+    {reply, ok, State};
 handle_call(close, _From, State) ->
     {stop, normal, ok, State};
 handle_call(doom, _From, State) ->