new cache design (based on multi-page idea)

.gitignore

@@ -8,5 +8,6 @@
 ebin/
 deps/
 .eunit/
+tests/
 rebar
 *.sublime-*

Emakefile

@@ -0,0 +1,7 @@
+{"src/*", [
+   report, 
+   verbose, 
+   {i, "include"}, 
+   {outdir, "ebin"},
+   debug_info 
+]}.

Makefile

@@ -1,5 +1,7 @@
 .PHONY: deps test
 
+BB=../basho_bench
+
 all: rebar deps compile
 
 compile:
@@ -31,3 +33,9 @@ rebar:
 	curl -O http://cloud.github.com/downloads/basho/rebar/rebar
 	chmod ugo+x rebar
 
+benchmark:
+	$(BB)/basho_bench priv/cache.benchmark
+	$(BB)/priv/summary.r -i tests/current
+	open tests/current/summary.png
+
+

priv/cache.benchmark

@@ -0,0 +1,26 @@
+{code_paths,      ["./ebin"]}.
+{log_level,       info}.
+{report_interval, 1}.
+{driver,          cache_benchmark}.
+
+%%
+%% workload
+{mode,           max}.
+{duration,         1}.
+{concurrent,      10}.
+{key_generator,   {uniform_int, 1000000}}.
+{value_generator, {fixed_bin, 1000}}.
+
+{operations, [
+   {put,    5} 
+  ,{get,    5}
+ %,{remove, 1} 
+]}.
+
+{cache,   [
+   {ttl,     20}
+  ,{n,       10} 
+  ,{policy, lru}
+  %,{size,   500000}
+  %,{memory, 400000000}
+]}.

src/cache.app.src

@@ -1,7 +1,7 @@
 {application, cache,
    [
       {description, "in-memory cache"},
-      {vsn,         "0.1.0"},
+      {vsn,         "0.2.0"},
       {modules,     [
          cache,
          cache_sup, 

src/cache.erl

@@ -1,49 +1,50 @@
 -module(cache).
--export([start/0]).
--export([start_link/2, i/1, put/3, get/2, evict/1, stop/1]).
-
-
-start() ->
-   AppFile = code:where_is_file(atom_to_list(?MODULE) ++ ".app"),
-   {ok, [{application, _, List}]} = file:consult(AppFile), 
-   Apps = proplists:get_value(applications, List, []),
-   lists:foreach(
-      fun(X) -> 
-         ok = case application:start(X) of
-            {error, {already_started, X}} -> ok;
-            Ret -> Ret
-         end
-      end,
-      Apps
-   ),
-   application:start(?MODULE).
 
+-export([
+   start_link/2, drop/1, i/1,
+   put/3, put_/3, get/2, has/2, remove/2, remove_/2
+]).
 
 %%
 %%
-start_link(Name, Opts) ->
-   cache_bucket:start_link(Name, Opts).
+start_link(Cache, Opts) ->
+   cache_bucket:start_link(Cache, Opts).
 
+%%
+%%
+drop(Cache) ->
+   erlang:exit(whereis(Cache), shutdown).
+
+%%
+%%
 i(Cache) ->
-   cache_bucket:i(Cache).   
+   gen_server:call(Cache, i).   
 
 %%
 %%
 put(Cache, Key, Val) ->
-   cache_bucket:put(Cache, Key, Val).
+   gen_server:call(Cache, {put, Key, Val}).
+
+put_(Cache, Key, Val) ->
+   gen_server:cast(Cache, {put, Key, Val}).
 
 %%
 %%
 get(Cache, Key) ->
-   cache_bucket:get(Cache, Key).
+   gen_server:call(Cache, {get, Key}).
 
 %%
 %%
-evict(Cache) ->
-   cache_bucket:evict(Cache).
+has(Cache, Key) ->
+   gen_server:call(Cache, {has, Key}).
 
 %%
 %%
-stop(Cache) ->
-   cache_bucket:stop(Cache).
+remove(Cache, Key) ->
+   gen_server:call(Cache, {remove, Key}).
+
+%%
+%%
+remove_(Cache, Key) ->
+   gen_server:cast(Cache, {remove, Key}).
 

src/cache.hrl

@@ -0,0 +1,19 @@
+
+
+%-define(VERBOSE, true).
+-ifdef(VERBOSE).
+   -define(DEBUG(Str, Args), error_logger:error_msg(Str, Args)).
+-else.
+   -define(DEBUG(Str, Args), ok).
+-endif.
+
+
+%% default cache eviction policy
+-define(DEF_CACHE_POLICY, lru).
+
+%% default cache ttl and number of generations
+-define(DEF_CACHE_TTL,   600).
+-define(DEF_CACHE_N,      10).
+
+%% default cache house keeping frequency
+-define(DEF_CACHE_QUOTA, 5000). 

src/cache_benchmark.erl

@@ -0,0 +1,66 @@
+%%   @description
+%%      basho_bench driver
+-module(cache_benchmark).
+
+-export([
+   new/1, run/4
+]).
+
+%%
+%%
+new(_Id) ->
+   try
+      lager:set_loglevel(lager_console_backend, basho_bench_config:get(log_level, info)),
+      init()
+   catch _:Err ->
+      error_logger:error_msg("cache failed: ~p", [Err]),
+      halt(1)
+   end,
+   {ok, undefined}.
+
+%%
+%%
+run(put, KeyGen, ValGen, S) ->
+   Key = KeyGen(),
+   case (catch cache:put(cache, Key, ValGen())) of
+      ok -> {ok, S};
+      E  -> {error, failure(p, Key, E), S}
+   end;
+
+run(get, KeyGen, _ValueGen, S) ->
+   Key = KeyGen(),
+   case (catch cache:get(cache, Key)) of
+      Val when is_binary(Val) -> {ok, S};
+      undefined               -> {ok, S};
+      E -> {error, failure(g, Key, E), S}
+   end;
+
+run(remove, KeyGen, _ValueGen, S) ->
+   Key = KeyGen(),
+   case (catch cache:remove(cache, Key)) of
+      ok -> {ok, S};
+      E  -> {error, failure(r, Key, E), S}
+   end;
+
+run(dump, _KeyGen, _ValueGen, S) ->
+   error_logger:info_msg("cache: ~p", [cache:i(cache)]),
+   {ok, S}.
+
+
+%%
+%%
+init() ->
+   case application:start(cache) of
+      {error, {already_started, _}} ->
+         ok;
+      ok ->
+         Cache   = basho_bench_config:get(cache, 30000),
+         {ok, _} = cache:start_link(cache, Cache)
+   end.
+
+%%
+%%
+failure(Tag, _Key, E) ->
+   %io:format("----> ~p~n", [process_info(pns:whereis(kv, Key))]),
+   io:format("~s -> ~p~n", [Tag, E]),
+   failed.

src/cache_bucket.erl

@@ -2,97 +2,73 @@
 -module(cache_bucket).
 -behaviour(gen_server).
 -author('Dmitry Kolesnikov <dmkolesnikov@gmail.com>').
+-include("cache.hrl").
 
--export([start_link/2]).
--export([i/1, put/3, get/2, evict/1, stop/1]).
--export([init/1, handle_call/3, handle_cast/2, handle_info/2, terminate/2, code_change/3]).
-
--define(DEFAULT_POLICY,     lru).
--define(DEFAULT_TTL,      60000).
--define(DEFAULT_EVICT,    10000).
--define(DEFAULT_CHUNK,      100).
+-export([
+   start_link/2,
+   init/1, handle_call/3, handle_cast/2, handle_info/2, terminate/2, code_change/3
+]).
 
+%%
 %%
 -record(cache, {
-   policy,    %%
-   memory,    %% memory threshold
-   size,      %% size threshold
-   chunk,     %% number of evicted elements 
+   name   :: atom(),     %% name of cache bucket
+   heap   :: list(),     %% heap
 
-   ttl,       %% cache element ttl
-   evict,     %% house keeping timer to evict cache elements
-   elements,
-   access,
+   n      = ?DEF_CACHE_N      :: integer(),  %% number of cells          
+   ttl    = ?DEF_CACHE_TTL    :: integer(),  %% chunk time to live
+   policy = ?DEF_CACHE_POLICY :: integer(),  %% eviction policy
+   evict                      :: integer(),  %% age of heap cell (cell eviction frequency)
 
-   hit,
-   miss
+   quota  = ?DEF_CACHE_QUOTA  :: integer(),  %% frequency of limit enforcement (clean-up)
+   quota_size   :: integer(),  %% max number of elements
+   quota_memory :: integer()   %% max number of memory in bytes
 }).
 
 %%
 %%
 start_link(Name, Opts) ->
-   gen_server:start_link({local, Name}, ?MODULE, [Opts], []).
+   gen_server:start_link({local, Name}, ?MODULE, [Name, Opts], []).
 
-init([Opts]) ->
-   init(Opts, #cache{
-      evict  = ?DEFAULT_EVICT,
-      policy = ?DEFAULT_POLICY,
-      chunk  = ?DEFAULT_CHUNK,
-      ttl    = ?DEFAULT_TTL * 1000,
-      hit    = 0,
-      miss   = 0
-   }).
+init([Name, Opts]) ->
+   {ok, init(Opts, #cache{name=Name})}.
 
 init([{policy, X} | T], #cache{}=S) ->
    init(T, S#cache{policy=X});
 
-init([{memory, X} | T], #cache{}=S) ->
-   init(T, S#cache{memory=X div erlang:system_info(wordsize)});
+init([{memory, X} | Opts], S) ->
+   init(Opts, S#cache{quota_memory=X div erlang:system_info(wordsize)});
 
-init([{size,  X} | T], #cache{}=S) ->
-   init(T, S#cache{size=X});
+init([{size,  X} | Opts],  S) ->
+   init(Opts, S#cache{quota_size=X});
 
-init([{chunk, X} | T], #cache{}=S) ->
-   init(T, S#cache{chunk=X});
+init([{n,   X} | Opts], S) ->
+   init(Opts, S#cache{n = X});
 
-init([{ttl, X} | T], #cache{}=S) ->
-   init(T, S#cache{ttl=X * 1000});
+init([{ttl, X} | Opts], S) ->
+   init(Opts, S#cache{ttl = X});
 
-init([{evict, X} | T], #cache{}=S) ->
-   init(T, S#cache{evict=X});
+init([{quota, X} | Opts], S) ->
+   init(Opts, S#cache{quota=X * 1000});
 
-init([], #cache{evict=Evict}=S) ->
+init([_ | Opts], S) ->
+   init(Opts, S);
+
+init([], S) ->
    random:seed(erlang:now()),
+   Evict = (S#cache.ttl div S#cache.n) * 1000,
+   erlang:send_after(S#cache.quota, self(), quota),
    erlang:send_after(Evict, self(), evict),
-   {ok,
    S#cache{
-         elements = ets:new(undefined, [set, private]),
-         access   = ets:new(undefined, [ordered_set, private])
-      }
+      heap  = cache_heap:new(S#cache.n),
+      evict = Evict
    }.
 
-%%%----------------------------------------------------------------------------   
-%%%
-%%% api 
-%%%
-%%%----------------------------------------------------------------------------   
-
 %%
 %%     
-i(Cache) ->
-   gen_server:call(Cache, info).
-
-put(Cache, Key, Val) ->
-	gen_server:cast(Cache, {put, Key, Val}).
-
-get(Cache, Key) ->
-   gen_server:call(Cache, {get, Key}, infinity).
-
-evict(Cache) ->
-   gen_server:cast(Cache, evict).
-
-stop(Cache) ->
-   gen_server:call(Cache, stop, infinity).
+terminate(_Reason, S) ->
+   cache_heap:free(S#cache.heap),
+   ok.
 
 %%%----------------------------------------------------------------------------   
 %%%
@@ -100,72 +76,51 @@ stop(Cache) ->
 %%%
 %%%----------------------------------------------------------------------------   
 
-%%
-%%
-handle_call(info, _Tx,  #cache{elements=E, access=A, hit=Hit, miss=Miss}=S) ->
-   Mem  = ets:info(E, memory) + ets:info(A, memory),
-   Size = ets:info(E, size),
-   Info = [
-      {memory, Mem},
-      {size,  Size},
-      {hit,    Hit},
-      {miss,  Miss}
-   ],
-   {reply, {ok, Info}, S};
+handle_call({put, Key, Val}, _, S) ->
+   {reply, ok, insert(Key, Val, S)};
 
-handle_call({get, Key}, _Tx, #cache{ttl=TTL, elements=E, access=A, hit=Hit, miss=Miss}=S) ->
-   Now = usec(),
-   case ets:lookup(E, Key) of
-   	[] -> 
-   	   {reply, none, S#cache{miss=Miss + 1}};
-   	[{Key, _Val, Expire0}] when Expire0 =< Now ->
-   	   {reply, none, S#cache{miss=Miss + 1}};
-   	[{Key, Val, Expire0}] ->
-   	   Expire = Now + TTL,
-   		ets:insert(E, {Key, Val, Expire}),
-   		ets:delete(A, Expire0),
-   		ets:insert(A, {Expire, Key}),
-   	   {reply, {ok, Val}, S#cache{hit=Hit + 1}}
+handle_call({get, Key}, _, S) ->
+   {reply, lookup(Key, S), S};
+
+handle_call({has, Key}, _, S) ->
+   case member(Key, S) of
+      true -> {reply, true,  S};
+      _    -> {reply, false, S}
    end;
 
-handle_call(stop, _Tx, S) ->
-   {stop, normal, ok, S};
+handle_call({remove, Key}, _, S) ->
+   {reply, ok, remove(Key, S)};
 
-handle_call(_Req,  _Tx, S) ->
-   {reply, {error, not_implemented}, S}.
+handle_call(i, _, S) ->
+   Cells  = cache_heap:cells(S#cache.heap), 
+   Size   = cache_heap:size(S#cache.heap), 
+   Memory = cache_heap:memory(S#cache.heap), 
+   {reply, [{heap, Cells}, {size, Size}, {memory, Memory}], S};
 
-%%
-%%
-handle_cast({put, Key, Val}, #cache{ttl=TTL, elements=E, access=A}=S) ->
-   Expire = usec() + TTL,
-   ets:insert(E, {Key, Val, Expire}),
-   ets:insert(A, {Expire, Key}),
-   {noreply, S};
-
-handle_cast(evict, #cache{elements=E, access=A}=S) ->
-   evict_expired(usec(), E, A),
-   evict_cache(S),
-   {noreply, S};
-
-handle_cast(_Req, S) ->
+handle_call(_, _, S) ->
    {noreply, S}.
 
 %%
 %%
-handle_info(evict, #cache{evict=Evict, elements=E, access=A}=S) ->
-   evict_expired(usec(), E, A),
-   evict_cache(S),
-   erlang:send_after(Evict, self(), evict),
-   {noreply, S};
+handle_cast({put, Key, Val}, S) ->
+   {noreply, insert(Key, Val, S)};
 
+handle_cast({remove, Key}, S) ->
+   {noreply, remove(Key, S)};
 
-handle_info(_Msg, S) ->
+handle_cast(_, S) ->
    {noreply, S}.
 
-%%
-%%     
-terminate(_Reason, _S) ->
-   ok.
+handle_info(evict, S) ->
+   erlang:send_after(S#cache.evict, self(), evict),
+   {noreply, evict(S)};
+
+handle_info(quota, S) ->
+   erlang:send_after(S#cache.quota, self(), quota),
+   {noreply, quota(S)};
+
+handle_info(_, S) ->
+   {noreply, S}.
 
 %%
 %% 
@@ -180,106 +135,143 @@ code_change(_Vsn, S, _Extra) ->
 %%%----------------------------------------------------------------------------   
 
 %%
-%%
-usec() ->
-   {Mega, Sec, USec} = erlang:now(),
-   (Mega * 1000000 + Sec) * 1000000 + USec.
-
-%%
-%%
-check_memory(#cache{memory=undefined}) ->
-   true;
-check_memory(#cache{memory=Mem, elements=E, access=A}) ->
-   Used = ets:info(E, memory) + ets:info(A, memory),
-   if
-      Used > Mem -> false;
-      true       -> true
-   end.
-
-%%
-%%
-check_size(#cache{size=undefined}) ->
-   true;
-check_size(#cache{size=Size, elements=E}) ->
-   Used = ets:info(E, size),
-   if
-      Used > Size -> false;
-      true        -> true
-   end.
-
-%%
-%%
-check(S) ->
-   case check_memory(S) of
-      true  -> check_size(S);
-      false -> false
-   end.
-
-%%
-%%
-evict_expired(Expire, Element, Access) ->
-   case ets:first(Access) of
-      '$end_of_table' ->
-         ok; 
-      Time when Time > Expire ->   
-         ok;
-      Time ->
-         [{_, Key}] = ets:lookup(Access, Time),
-   	   ets:delete(Element, Key),
-   	   ets:delete(Access, Time),
-   	   evict_expired(Expire, Element, Access)
-  	end.
-
-%%
-%%
-evict_cache(#cache{policy=lru, chunk=Chunk, elements=E, access=A}=S) ->
-   case check(S) of
+%% evict key from cells 
+evict_key(Key, List) ->
+   dowhile(
+      fun(Cell) -> 
+         case ets:member(Cell, Key) of
             true   -> 
-         ok;
-      false ->
-         N = erlang:max(1, random:uniform(Chunk)), 
-         evict_lru(N, E, A),
-         evict_cache(S)
+               ets:delete(Cell, Key),
+               Cell;
+            Result -> 
+               Result
+         end
+      end,
+      List
+   ).
+
+%%
+%%
+insert(Key, Val, #cache{}=S) ->
+   [Head | Tail] = cache_heap:cells(S#cache.heap),
+   true = ets:insert(Head, {Key, Val}),
+   _    = evict_key(Key, Tail),
+   ?DEBUG("cache ~p: put ~p to cell ~p~n", [S#cache.name, Key, Head]),
+   S.
+
+%%
+%%
+remove(Key, S) ->
+   Cell = evict_key(Key, cache_heap:cells(S#cache.heap)),
+   ?DEBUG("cache ~p: remove ~p in cell ~p~n", [S#cache.name, Key, Cell]),
+   S.
+
+%%
+%%
+member(Key, S) ->
+   dowhile(
+      fun(X) -> ets:member(X, Key) end,
+      cache_heap:cells(S#cache.heap)
+   ).  
+
+%%
+%%
+lookup(Key, #cache{policy=mru}=S) ->
+   % cache always evicts last generation
+   % MRU caches do not prolong recently used entity
+   dowhile(
+      fun(Cell) ->
+         case ets:lookup(Cell, Key) of
+            [] ->
+               false;
+            [{_, Val}] ->
+               ?DEBUG("cache ~p: get ~p at cell ~p~n", [S#cache.name, Key, Cell]),
+               Val
+         end
+      end,
+      lists:reverse(cache_heap:cells(S#cache.heap))
+   );
+
+lookup(Key, S) ->
+   [Head | Tail] = cache_heap:cells(S#cache.heap),
+   case ets:lookup(Head, Key) of
+      % no value at head chunk, lookup and evict tail 
+      [] ->
+         dowhile(
+            fun(Cell) ->
+               case ets:lookup(Cell, Key) of
+                  [] ->
+                     false;
+                  [{_, Val}] ->
+                     ?DEBUG("cache ~p: get ~p at cell ~p~n", [S#cache.name, Key, Cell]),
+                     _    = ets:delete(Cell, Key),
+                     true = ets:insert(Head, {Key, Val}),
+                     Val
+               end
+            end,
+            Tail
+         );
+      [{_, Val}] -> 
+         ?DEBUG("cache ~p: get ~p in cell ~p~n", [S#cache.name, Key, Head]),
+         Val
+   end.
+
+%%
+%% execute predicate while it succeeded
+dowhile(Pred, [Head | Tail]) ->
+   case Pred(Head) of
+      % predicate false, apply predicate to next chunk
+      false  -> dowhile(Pred, Tail);
+      Result -> Result
    end;
 
-evict_cache(#cache{policy=mru, chunk=Chunk, elements=E, access=A}=S) ->
-   case check(S) of
-      true  -> 
-         ok;
-      false ->
-         N = erlang:max(1, random:uniform(Chunk)), 
-         evict_mru(N, E, A),
-         evict_cache(S)
+dowhile(_Pred, []) ->
+   undefined.
+
+%%
+%%
+evict(#cache{}=S) ->
+   Cell = cache_heap:last(S#cache.heap),
+   ?DEBUG("cache ~p: free cell ~p~n", [S#cache.name, Cell]),
+   S#cache{
+      heap = cache_heap:alloc(cache_heap:free(Cell, S#cache.heap))
+   }.
+
+drop(#cache{}=S) ->
+   Cell = cache_heap:last(S#cache.heap),
+   ?DEBUG("cache ~p: free cell ~p~n", [S#cache.name, Cell]),
+   S#cache{
+      heap = cache_heap:free(Cell, S#cache.heap)
+   }.
+
+%%
+%%
+quota(#cache{}=S) ->
+   maybe_memory_quota(
+      maybe_size_quota(S)
+   ).
+
+
+maybe_size_quota(#cache{quota_size=undefined}=S) ->
+   S;
+maybe_size_quota(S) ->
+   case lists:sum(cache_heap:size(S#cache.heap)) of
+      Size when Size > S#cache.quota_size ->
+         maybe_size_quota(drop(S));
+      _ ->
+         S#cache{
+            heap = cache_heap:talloc(S#cache.n, S#cache.heap)
+         }
    end.
 
-
-%%
-%%
-evict_lru(0, _Element, _Access) ->
-   ok;
-evict_lru(N, Element, Access) ->
-   case ets:first(Access) of
-      '$end_of_table' ->
-         ok; 
-      Time ->
-         [{_, Key}] = ets:lookup(Access, Time),
-         ets:delete(Element, Key),
-         ets:delete(Access, Time),
-         evict_lru(N - 1, Element, Access)
+maybe_memory_quota(#cache{quota_memory=undefined}=S) ->
+   S;
+maybe_memory_quota(S) ->
+   case lists:sum(cache_heap:memory(S#cache.heap)) of
+      Size when Size > S#cache.quota_memory ->
+         maybe_memory_quota(drop(S));
+      _ ->
+         S#cache{
+            heap = cache_heap:talloc(S#cache.n, S#cache.heap)
+         }
    end.
-
-%%
-%%
-evict_mru(0, _Element, _Access) ->
-   ok;
-evict_mru(N, Element, Access) ->
-   case ets:last(Access) of
-      '$end_of_table' ->
-         ok; 
-      Time ->
-         [{_, Key}] = ets:lookup(Access, Time),
-         ets:delete(Element, Key),
-         ets:delete(Access, Time),
-         evict_mru(N - 1, Element, Access)
-   end.
-

src/cache_heap.erl

@@ -0,0 +1,97 @@
+%%
+%%   Copyright (c) 2012, Dmitry Kolesnikov
+%%   All Rights Reserved.
+%%
+%%  This library is free software; you can redistribute it and/or modify
+%%  it under the terms of the GNU Lesser General Public License, version 3.0
+%%  as published by the Free Software Foundation (the "License").
+%%
+%%  Software distributed under the License is distributed on an "AS IS"
+%%  basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
+%%  the License for the specific language governing rights and limitations
+%%  under the License.
+%% 
+%%  You should have received a copy of the GNU Lesser General Public
+%%  License along with this library; if not, write to the Free Software
+%%  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
+%%  USA or retrieve online http://www.opensource.org/licenses/lgpl-3.0.html
+%%
+%%  @description
+%%     heap of ETS entities (sorted by age)
+-module(cache_heap).
+
+-export([
+   new/1, alloc/1, talloc/2, free/1, free/2,
+   cells/1, size/1, memory/1, last/1, first/1
+]).
+
+-record(heap, {
+   cells :: list()      %% list of cells
+}).
+
+%%
+%% create new heap
+new(N) ->
+   lists:foldl(
+      fun(_, Acc) -> alloc(Acc) end,
+      #heap{cells=[]},
+      lists:seq(1, N)
+   ).
+
+%%
+%% allocate new cell
+alloc(#heap{}=H) ->
+   H#heap{
+      cells = [create() | H#heap.cells]
+   }.
+
+% tail alloc
+talloc(N, #heap{}=H) 
+ when length(H#heap.cells) < N ->
+   talloc(N,
+      H#heap{
+         cells = H#heap.cells ++ [create()]
+      }
+   );
+talloc(_, #heap{}=H) ->
+   H.
+
+create() ->
+   ets:new(undefined, [set, protected]).
+
+%%
+%% free cells
+free(#heap{cells=Cells}) ->
+   [ets:delete(X) || {_, X} <- Cells],
+   ok.
+
+free(Cell, #heap{}=H) ->
+   ets:delete(Cell),
+   H#heap{
+      cells = lists:delete(Cell, H#heap.cells)
+   }.
+
+%%
+%%
+cells(#heap{}=H) ->
+   H#heap.cells.
+
+%%
+%%
+size(#heap{}=H) ->
+   [ets:info(X, size) || X <- H#heap.cells].
+
+%%
+%%
+memory(#heap{}=H) ->
+   [ets:info(X, memory) || X <- H#heap.cells].
+
+%%
+%%
+last(#heap{}=H) ->
+   lists:last(H#heap.cells).
+
+%%
+%%
+first(#heap{}=H) ->
+   hd(H#heap.cells).

src/cache_sup.erl

@@ -1,14 +1,15 @@
 %%
 -module(cache_sup).
 -behaviour(supervisor).
--author('Dmitry Kolesnikov <dmkolesnikov@gmail.com>').
 
 -export([start_link/0, init/1]).
 
 %%
 %%
 start_link() ->
-   supervisor:start_link({local, ?MODULE}, ?MODULE, []).
+   {ok, Sup} = supervisor:start_link({local, ?MODULE}, ?MODULE, []),
+   lists:foreach(fun default_cache/1, default()),
+   {ok, Sup}.
    
 init([]) -> 
    {ok,
@@ -17,3 +18,18 @@ init([]) ->
          []
       }
    }.
+
+
+%% list of default caches
+default() ->
+   case application:get_env(cache, default) of
+      {ok, Val} -> Val;
+      undefined ->  []
+   end.
+
+default_cache({Name, Opts}) ->
+   supervisor:start_child(?MODULE, {
+      Name,
+      {cache, start_link, [Name, Opts]},
+      permanent, 900000, worker, dynamic
+   }).

test/cache_tests.erl

@@ -2,132 +2,170 @@
 -author('Dmitry Kolesnikov <dmkolesnikov@gmail.com>').
 -include_lib("eunit/include/eunit.hrl").
 
+-define(CACHE, [
+   {ttl,   3},   %% time-to-live 3 sec
+   {n,     3},   %% 3 cells
+   {evict, 1}    %% evict 1 sec
+]).
 
-lifecyle_1_test() ->
-   cache:start(),
-   {ok, _} = cache:start_link(test, [
-   	{ttl,   10},
-   	{evict,  5}
-   ]),
+lru_test_() ->
+   {
+      setup,
+      fun cache_init/0,
+      fun cache_free/1,
+      [
+         {"put",         fun cache_put/0}
+        ,{"has",         fun cache_has/0}
+        ,{"get",         fun cache_get/0}
+        ,{"del",         fun cache_del/0}
+        ,{"lifecycle 1", {timeout, 10000, fun cache_lc1/0}}
+      ]
+   }.
+
+cache_init() ->
+   cache:start_link(test, ?CACHE).
+
+cache_free({ok, Pid}) ->
+   erlang:unlink(Pid),
+   cache:drop(test).
+
+cache_put() ->
+   ok = cache:put(test, <<"key">>, <<"val">>).
+
+cache_has() ->
+   true  = cache:has(test, <<"key">>),
+   false = cache:has(test, <<"yek">>).
+
+cache_get() ->
+   <<"val">> = cache:get(test, <<"key">>),
+   undefined = cache:get(test, <<"yek">>).
+
+cache_del() ->
+   ok = cache:remove(test, <<"key">>),
+   ok = cache:remove(test, <<"yek">>).
+
+cache_lc1() ->
+   error_logger:error_msg("~n~n life-cycle #1"),
    ok  = cache:put(test, key, val),
-   timer:sleep(6),
-   {ok, val} = cache:get(test, key),
-   timer:sleep(6),
-   {ok, val} = cache:get(test, key),
-   timer:sleep(20),
-   none = cache:get(test, key),
-   cache:stop(test).
+   timer:sleep(1200),
+   val = cache:get(test, key),
+   timer:sleep(1200),
+   val = cache:get(test, key),
+   timer:sleep(1200),
+   val = cache:get(test, key),
+   timer:sleep(3200),
+   undefined = cache:get(test, key).
 
 
-lifecyle_2_test() ->
-   cache:start(),
-   {ok, _} = cache:start_link(test, [
-   	{ttl,     10},
-   	{evict,  100}
-   ]),
-   ok = cache:put(test, key, val),
-   timer:sleep(6),
-   {ok, val} = cache:get(test, key),
-   timer:sleep(6),
-   {ok, val} = cache:get(test, key),
-   timer:sleep(20),
-   none = cache:get(test, key),
-   cache:stop(test).
+% lifecyle_2_test() ->
+%    cache:start(),
+%    {ok, _} = cache:start_link(test, [
+%    	{ttl,     10},
+%    	{evict,  100}
+%    ]),
+%    ok = cache:put(test, key, val),
+%    timer:sleep(6),
+%    {ok, val} = cache:get(test, key),
+%    timer:sleep(6),
+%    {ok, val} = cache:get(test, key),
+%    timer:sleep(20),
+%    none = cache:get(test, key),
+%    cache:stop(test).
 
-lifecyle_3_test() ->
-   cache:start(),
-   {ok, _} = cache:start_link(test, [
-   	{ttl,   10},
-   	{evict,  5}
-   ]),
-   ok = cache:put(test, key1, val1),
-   timer:sleep(5),
-   ok = cache:put(test, key2, val2),
-   timer:sleep(5),
-   ok = cache:put(test, key3, val3),
-   timer:sleep(5),
-   ok = cache:put(test, key4, val4),
+% lifecyle_3_test() ->
+%    cache:start(),
+%    {ok, _} = cache:start_link(test, [
+%    	{ttl,   10},
+%    	{evict,  5}
+%    ]),
+%    ok = cache:put(test, key1, val1),
+%    timer:sleep(5),
+%    ok = cache:put(test, key2, val2),
+%    timer:sleep(5),
+%    ok = cache:put(test, key3, val3),
+%    timer:sleep(5),
+%    ok = cache:put(test, key4, val4),
 
-   none = cache:get(test, key1),
-	none = cache:get(test, key2),
-   {ok, val3} = cache:get(test, key3),
-   {ok, val4} = cache:get(test, key4),
-   cache:stop(test).
+%    none = cache:get(test, key1),
+% 	none = cache:get(test, key2),
+%    {ok, val3} = cache:get(test, key3),
+%    {ok, val4} = cache:get(test, key4),
+%    cache:stop(test).
 
-evict_lru_1_test() ->
-   cache:start(),
-   {ok, _} = cache:start_link(test, [
-   	{policy, lru},
-   	{ttl,    100},
-   	{evict,    5},
-   	{size,    10},
-   	{chunk,    2}
-   ]),
-   lists:foreach(
-   	fun(X) -> cache:put(test, X, X) end,
-   	lists:seq(1, 10)
-   ),
-   timer:sleep(10),
-   {ok, 1} = cache:get(test, 1),
-   cache:put(test, key, val),
-   timer:sleep(10),
-   none = cache:get(test, 2),
-   cache:stop(test).
+% evict_lru_1_test() ->
+%    cache:start(),
+%    {ok, _} = cache:start_link(test, [
+%    	{policy, lru},
+%    	{ttl,    100},
+%    	{evict,    5},
+%    	{size,    10},
+%    	{chunk,    2}
+%    ]),
+%    lists:foreach(
+%    	fun(X) -> cache:put(test, X, X) end,
+%    	lists:seq(1, 10)
+%    ),
+%    timer:sleep(10),
+%    {ok, 1} = cache:get(test, 1),
+%    cache:put(test, key, val),
+%    timer:sleep(10),
+%    none = cache:get(test, 2),
+%    cache:stop(test).
 
-evict_lru_2_test() ->
-   cache:start(),
-   {ok, _} = cache:start_link(test, [
-   	{policy, lru},
-   	{ttl,    100},
-   	{evict,  100},
-   	{size,    10},
-   	{chunk,    2}
-   ]),
-   lists:foreach(
-   	fun(X) -> cache:put(test, X, X) end,
-   	lists:seq(1, 10)
-   ),
-   {ok, 1} = cache:get(test, 1),
-   cache:put(test, key, val),
-   cache:evict(test),
-   none = cache:get(test, 2),
-   cache:stop(test).
+% evict_lru_2_test() ->
+%    cache:start(),
+%    {ok, _} = cache:start_link(test, [
+%    	{policy, lru},
+%    	{ttl,    100},
+%    	{evict,  100},
+%    	{size,    10},
+%    	{chunk,    2}
+%    ]),
+%    lists:foreach(
+%    	fun(X) -> cache:put(test, X, X) end,
+%    	lists:seq(1, 10)
+%    ),
+%    {ok, 1} = cache:get(test, 1),
+%    cache:put(test, key, val),
+%    cache:evict(test),
+%    none = cache:get(test, 2),
+%    cache:stop(test).
 
-evict_mru_1_test() ->
-   cache:start(),
-   {ok, _} = cache:start_link(test, [
-   	{policy, mru},
-   	{ttl,    100},
-   	{evict,    5},
-   	{size,    10},
-   	{chunk,    2}
-   ]),
-   lists:foreach(
-   	fun(X) -> cache:put(test, X, X) end,
-   	lists:seq(1, 10)
-   ),
-   timer:sleep(10),
-   {ok, 1} = cache:get(test, 1),
-   cache:put(test, key, val),
-   timer:sleep(10),
-   none = cache:get(test, key),
-   cache:stop(test).
+% evict_mru_1_test() ->
+%    cache:start(),
+%    {ok, _} = cache:start_link(test, [
+%    	{policy, mru},
+%    	{ttl,    100},
+%    	{evict,    5},
+%    	{size,    10},
+%    	{chunk,    2}
+%    ]),
+%    lists:foreach(
+%    	fun(X) -> cache:put(test, X, X) end,
+%    	lists:seq(1, 10)
+%    ),
+%    timer:sleep(10),
+%    {ok, 1} = cache:get(test, 1),
+%    cache:put(test, key, val),
+%    timer:sleep(10),
+%    none = cache:get(test, key),
+%    cache:stop(test).
 
-evict_mru_2_test() ->
-   cache:start(),
-   {ok, _} = cache:start_link(test, [
-   	{policy, mru},
-   	{ttl,    100},
-   	{evict,  100},
-   	{size,    10},
-   	{chunk,    2}
-   ]),
-   lists:foreach(
-   	fun(X) -> cache:put(test, X, X) end,
-   	lists:seq(1, 10)
-   ),
-   {ok, 1} = cache:get(test, 1),
-   cache:put(test, key, val),
-   cache:evict(test),
-   none = cache:get(test, key),
-   cache:stop(test).
+% evict_mru_2_test() ->
+%    cache:start(),
+%    {ok, _} = cache:start_link(test, [
+%    	{policy, mru},
+%    	{ttl,    100},
+%    	{evict,  100},
+%    	{size,    10},
+%    	{chunk,    2}
+%    ]),
+%    lists:foreach(
+%    	fun(X) -> cache:put(test, X, X) end,
+%    	lists:seq(1, 10)
+%    ),
+%    {ok, 1} = cache:get(test, 1),
+%    cache:put(test, key, val),
+%    cache:evict(test),
+%    none = cache:get(test, key),
+%    cache:stop(test).