From b101b2095fe406511559bac22e2d50ba5bea092e Mon Sep 17 00:00:00 2001
From: Linus Nordberg <linus@nordberg.se>
Date: Fri, 12 Sep 2014 17:52:34 +0200
Subject: Add docu in comments, rename two external functions, add a larger
 test.

---
 src/ht.erl | 31 +++++++++++++++++++++++--------
 1 file changed, 23 insertions(+), 8 deletions(-)

(limited to 'src')

diff --git a/src/ht.erl b/src/ht.erl
index a51924d..8118274 100644
--- a/src/ht.erl
+++ b/src/ht.erl
@@ -23,7 +23,7 @@
 -behaviour(gen_server).
 
 -export([size/0, add/1, tree_hash/0, tree_hash/1]).
--export([get_incl/2, get_cons/2]).
+-export([path/2, consistency/2]).
 -export([start_link/0, start_link/1, stop/0]).
 -export([init/1, handle_call/3, terminate/2, handle_cast/2, handle_info/2,
          code_change/3]).
@@ -54,9 +54,9 @@ tree_hash() ->
     gen_server:call(?MODULE, tree_hash).
 tree_hash(Version) ->
     gen_server:call(?MODULE, {tree_hash, Version}).
-get_incl(I, V) ->
-    gen_server:call(?MODULE, {inclusion, I, V}).
-get_cons(V1, V2) ->
+path(I, V) ->
+    gen_server:call(?MODULE, {path, I, V}).
+consistency(V1, V2) ->
     gen_server:call(?MODULE, {consistency, V1, V2}).
 
 %% gen_server callbacks
@@ -84,7 +84,7 @@ handle_call(tree_hash, _From, State) ->
 handle_call({tree_hash, Version}, _From, State) ->
     {NewState, Hash} = tree_hash(State, Version),
     {reply, Hash, NewState};
-handle_call({inclusion, _Index, _Version}, _From, State) ->
+handle_call({path, _Index, _Version}, _From, State) ->
     {reply, nyi, State};
 handle_call({consistency, _Version1, _Version2}, _From, State) ->
     {reply, nyi, State}.
@@ -206,16 +206,22 @@ update_layer(Tree, Layer, ICur, ILast) ->
 update_parent(S, Layer, I, ILast) when I >= ILast ->
     %% We're done updating parents. If ILast is a left child, copy it
     %% to where its parent would've been were it a right child. This
-    %% is a "placeholder node" which simplifies when creating
-    %% incomplete ("non-frozen") trees.
+    %% is a "placeholder node" which simplifies creating incomplete
+    %% ("non-frozen") trees.
     case right_node_p(ILast) of
         true -> S;
         _ -> ts:append(S, Layer + 1, ts:retrieve_hash(S, {ILast, Layer}))
     end;
 update_parent(S, Layer, I, ILast) ->
     false = right_node_p(I),                    % ASSERTION
-    %% Make an inner node hash of I and sibling. Store it as
+    %% Make an inner node hash of I and its sibling. Store it as
     %% parent. Recurse with next pair of leaves.
+    %% TODO: This is the only place where we store rather than
+    %% append. Consider changing this to an append. This would make it
+    %% possible for ts to use other data structures for the storage
+    %% (like a binary per layer). If so, don't forget to truncate
+    %% Layer+1 before appending if there's already a parent for I
+    %% there.
     update_parent(ts:store(S, {parent(I), Layer + 1},
                   mkinnerhash(ts:retrieve_hash(S, {I, Layer}),
                               ts:retrieve_hash(S, {I + 1, Layer}))),
@@ -304,6 +310,15 @@ old_versions_test() ->
                              tree_hash(X - 1)) end,
       random_entries(length(?TEST_VECTOR_LEAVES))).
 
+old_versions_bigger_test() ->
+    LEAVES = [<<X:32>> || X <- lists:seq(0, 512)],
+    test_init(LEAVES),
+    ?assertEqual(mth(LEAVES), tree_hash()),
+    lists:foreach(
+      fun(X) -> ?assertEqual(mth(lists:sublist(LEAVES, X)),
+                             tree_hash(X - 1)) end,
+      random_entries(length(LEAVES))).
+
 %%%%%%%%%%%%%%%%%%%%
 %% Testing the test helpers.
 mth_test() ->
-- 
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