Max value version of eleveldb

.gitignore

@@ -1,10 +1,7 @@
-m
+_build/
+*.beam
 .eunit
-deps/*
-ebin/*
-rel/antidote
 dev
-apps/antidote/src/*
 *.swp
 *.swo
 src/*.swo
@@ -13,9 +10,16 @@ dialyzer_unhandled_warnings
 dialyzer_warnings
 doc/
 .DS_Store
-log/
+logs/
 tags
 rel/vars/*.config
-.rebar/*
-*.dump
-
+rebar.lock
+docs/_site/
+docs/.sass-cache/
+docs/.jekyll-metadata
+docs/_pdf
+docs/.idea/
+log/
+data/
+compile_commands.json
+test/.rebar3/

README.md

@@ -1,10 +1,44 @@
 # AntidoteDB  
 
-Erlang Rebar application, used as the DataStore for [Antidote](https://github.com/SyncFree/antidote). This module exposes a simple API, so the datastore can be configurable and changed, without affecting Antidote code. 
+Erlang Rebar application, used as the backend DataStore for [Antidote](https://github.com/SyncFree/antidote). This module exposes a simple API, so the datastore can be configurable and changed, without affecting Antidote code. 
+
+This project is structured as a rebar3 project, and today contains two modules:
+
++ **antidote_db**: contains a basic API to interact with the DB. Today it only contains the methods for a eleveldb backend.
++ **leveldb_wrapper**: contains a wrapper of the API provided by eleveldb, with added code containing Antidote logic.
+
+All tests are under the respective *_SUITE modules, and should be run using `rebar3 ct`.
 
 ## ElevelDB  
 
 Today, this application uses SyncFree [ElevelDB](https://github.com/SyncFree/eleveldb) fork.
 
 As this application is intended to be used in [Antidote](https://github.com/SyncFree/antidote), it uses the 'Antidote Comparator' by default. 
 
+### Composition of keys
+
+Keys are composed as follows:
+
+`{antidote_key, max_value_in_vc, vc_hash, op/snap, vc}`
+
++ **antidote_key**: Same key as in Antidote. 
++ **max_value_in_vc**: The max value for all DCs in the VC.
++ **vc_hash**: A hash of the VC. This is done in order to provide a more performant sorting algorithm, since we don't need to compare all the VC, to find that keys are different. If the hash matches, we also compare the VC, just to make sure it's not a collision. 
++ **op/snap**: an atom indicating if the stored value corresponds to an operation or a snapshot.
++ **vc**: the vc of when the op/snap ocurred.
+
+### Sorting of keys
+
+Keys get sorted first by the Antidote key.
+Then we look at the MAX value of it's VC, sorting first the biggest one. We reverse the "natural" order, so we can have the most recent operations first.
+If the max value for two keys matches, we sort taking into account the hash value.
+For matching hashes, we check the rest of the key, sorting accordingly.
+
+### Testing
+
+As stated before, the modules have their corresponding *_SUITE modules for unit testing. The antidote_db module uses [meck](https://github.com/eproxus/meck) to mock the calls to eleveldb and the leveldb_wrapper. 
+
+In addition to this tests, and thanks to @peterzeller, we have a Proper module to test the get_ops method. This module generates operations by simulating incrementing a
+vectorclock and merging them. This tests can be run using "rebar3 proper -m prop_get_ops -n TESTS" where TESTS is the amount of random inputs that Proper should run with.
+
+This two modules have more than a 90% code coverage.

rebar.config

@@ -0,0 +1,26 @@
+{deps, [
+    {eleveldb, ".*", {git, "git://github.com/SyncFree/eleveldb", {branch, "max_order_comparator"}}},
+    {antidote_utils, ".*", {git, "git://github.com/SyncFree/antidote_utils", {branch, "additions_for_antidote_db"}}},
+    {meck, ".*", {git, "https://github.com/eproxus/meck.git", {tag, "0.8.3"}}}
+]}.
+
+%% Required to assemble a native library like eleveldb when compiling with Rebar3
+{overrides, [
+    {override, eleveldb, [
+        {plugins, [pc]},
+        {artifacts, ["priv/eleveldb.so"]},
+
+        {provider_hooks, [
+            {post, [
+                {compile, {pc, compile}},
+                {clean, {pc, clean}}
+            ]}
+        ]}
+    ]}
+]}.
+
+{plugins, [rebar3_proper]}.
+
+{profiles,
+    [{test, [{deps, [{proper, "1.1.1-beta"}]}]}]
+}.

src/antidote_db.app.src

@@ -0,0 +1,13 @@
+{application, antidote_db,
+ [
+  {description, "Antidote DataBase application"},
+  {vsn, "1"},
+  {registered, []},
+  {applications, [
+                  kernel,
+                  stdlib,
+                  eleveldb
+                 ]},
+  {mod, { antidote_db, []}},
+  {env, []}
+ ]}.

src/antidote_db.erl

@@ -0,0 +1,114 @@
+%% -------------------------------------------------------------------
+%%
+%% Copyright (c) 2014 SyncFree Consortium.  All Rights Reserved.
+%%
+%% This file is provided to you under the Apache License,
+%% Version 2.0 (the "License"); you may not use this file
+%% except in compliance with the License.  You may obtain
+%% a copy of the License at
+%%
+%%   http://www.apache.org/licenses/LICENSE-2.0
+%%
+%% Unless required by applicable law or agreed to in writing,
+%% software distributed under the License is distributed on an
+%% "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+%% KIND, either express or implied.  See the License for the
+%% specific language governing permissions and limitations
+%% under the License.
+%%
+%% -------------------------------------------------------------------
+
+-module(antidote_db).
+
+-include_lib("antidote_utils/include/antidote_utils.hrl").
+
+-export([
+    new/2,
+    close_and_destroy/2,
+    close/1,
+    get_snapshot/3,
+    put_snapshot/3,
+    get_ops/4,
+    put_op/4]).
+
+-type antidote_db() :: {leveldb, eleveldb:db_ref()}.
+
+-type antidote_db_type() :: leveldb.
+
+-export_type([antidote_db/0, antidote_db_type/0]).
+
+%% Given a name, returns a new AntidoteDB (for now, only ElevelDB is supported)
+%% OpenOptions are set to use Antidote special comparator in the case of Eleveldb
+-spec new(atom(), antidote_db_type()) -> {ok, antidote_db()} | {error, any()}.
+new(Name, Type) ->
+    case Type of
+        leveldb ->
+            {ok, Ref} = eleveldb:open(Name, [{create_if_missing, true}, {antidote, true}]),
+            {ok, {leveldb, Ref}};
+        _ ->
+            {error, type_not_supported}
+    end.
+
+
+%% Closes and destroys the given base
+-spec close_and_destroy(antidote_db(), atom()) -> ok | {error, any()}.
+close_and_destroy({Type, DB}, Name) ->
+    case Type of
+        leveldb ->
+            eleveldb:close(DB),
+            eleveldb:destroy(Name, []);
+        _ ->
+            {error, type_not_supported}
+    end.
+
+-spec close(antidote_db()) -> ok | {error, any()}.
+close({Type, DB}) ->
+    case Type of
+        leveldb ->
+            eleveldb:close(DB);
+        _ ->
+            {error, type_not_supported}
+    end.
+
+%% Gets the most suitable snapshot for Key that has been committed
+%% before CommitTime. If its nothing is found, returns {error, not_found}
+-spec get_snapshot(antidote_db:antidote_db(), key(),
+    snapshot_time()) -> {ok, #materialized_snapshot{}} | {error, not_found}.
+get_snapshot({Type, DB}, Key, CommitTime) ->
+    case Type of
+        leveldb ->
+            leveldb_wrapper:get_snapshot(DB, Key, CommitTime);
+        _ ->
+            {error, type_not_supported}
+    end.
+
+%% Saves the snapshot into AntidoteDB
+-spec put_snapshot(antidote_db:antidote_db(), key(), #materialized_snapshot{}) -> ok | error.
+put_snapshot({Type, DB}, Key, Snapshot) ->
+    case Type of
+        leveldb ->
+            leveldb_wrapper:put_snapshot(DB, Key, Snapshot);
+        _ ->
+            {error, type_not_supported}
+    end.
+
+%% Returns a list of operations that have commit time in the range [VCFrom, VCTo]
+-spec get_ops(antidote_db:antidote_db(), key(), vectorclock(), vectorclock()) -> [#log_record{}].
+get_ops({Type, DB}, Key, VCFrom, VCTo) ->
+    case Type of
+        leveldb ->
+            leveldb_wrapper:get_ops(DB, Key, VCFrom, VCTo);
+        _ ->
+            {error, type_not_supported}
+    end.
+
+
+%% Saves the operation into AntidoteDB
+-spec put_op(antidote_db:antidote_db(), key(), vectorclock(), #log_record{}) -> ok | error.
+put_op({Type, DB}, Key, VC, Record) ->
+    case Type of
+        leveldb ->
+            leveldb_wrapper:put_op(DB, Key, VC, Record);
+        _ ->
+            {error, type_not_supported}
+    end.

src/antidote_db_sup.erl

@@ -0,0 +1,45 @@
+%% -------------------------------------------------------------------
+%%
+%% Copyright (c) 2014 SyncFree Consortium.  All Rights Reserved.
+%%
+%% This file is provided to you under the Apache License,
+%% Version 2.0 (the "License"); you may not use this file
+%% except in compliance with the License.  You may obtain
+%% a copy of the License at
+%%
+%%   http://www.apache.org/licenses/LICENSE-2.0
+%%
+%% Unless required by applicable law or agreed to in writing,
+%% software distributed under the License is distributed on an
+%% "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+%% KIND, either express or implied.  See the License for the
+%% specific language governing permissions and limitations
+%% under the License.
+%%
+%% -------------------------------------------------------------------
+-module(antidote_db_sup).
+
+-behaviour(supervisor).
+
+%% API
+-export([start_link/0]).
+
+%% Supervisor callbacks
+-export([init/1]).
+
+%% Helper macro for declaring children of supervisor
+-define(CHILD(I, Type), {I, {I, start_link, []}, permanent, 5000, Type, [I]}).
+
+%% ===================================================================
+%% API functions
+%% ===================================================================
+
+start_link() ->
+    supervisor:start_link({local, ?MODULE}, ?MODULE, []).
+
+%% ===================================================================
+%% Supervisor callbacks
+%% ===================================================================
+
+init([]) ->
+    {ok, { {one_for_one, 5, 10}, []} }.