Add eval command, edit Readme file

.editorconfig

@@ -0,0 +1,12 @@
+root = true
+
+[*]
+end_of_line = lf
+insert_final_newline = true
+charset = utf-8
+trim_trailing_whitespace = true
+insert_final_newline = true
+
+[*.erl]
+indent_style = space
+indent_size = 4

README.md

@@ -5,13 +5,11 @@
 ## Description
 
 eredis_cluster is a wrapper for eredis to support cluster mode of redis 3.0.0+
-This project is under development.
 
 ## TODO
 
-- Fix/Add specs of functions
-- Add safeguard if keys of a pipeline command is not located in the same server
-- Improve unit tests
+- Improve test suite to demonstrate the case where redis cluster is crashing,
+resharding, recovering...
 
 ## Compilation && Test
 
@@ -51,6 +49,11 @@ eredis_cluster:q(["GET","abc"]).
 %% Pipeline
 eredis_cluster:qp([["LPUSH", "a", "a"], ["LPUSH", "a", "b"], ["LPUSH", "a", "c"]]).
 
+%% Pipeline in multiple node (keys are sorted by node, a pipeline request is
+%% made on each node, then the result is aggregated and returned. The response
+%% keep the command order
+eredis_cluster:qmn([["GET", "a"], ["GET", "b"], ["GET", "c"]]).
+
 %% Transaction
 eredis_cluster:transaction([["LPUSH", "a", "a"], ["LPUSH", "a", "b"], ["LPUSH", "a", "c"]]).
 
@@ -84,6 +87,13 @@ eredis_cluster:update_key("abc", Fun).
 Fun = fun(Var) -> binary_to_integer(Var) + 1 end,
 eredis_cluster:update_hash_field("abc", "efg", Fun).
 
+%% Eval script, both script and hash are necessary to execute the command,
+%% the script hash should be precomputed at compile time otherwise, it will
+%% execute it at each request. Could be solved by using a macro though.  
+Script = "return redis.call('set', KEYS[1], ARGV[1]);",
+ScriptHash = "4bf5e0d8612687699341ea7db19218e83f77b7cf",
+eredis_cluster:eval(Script, ScriptHash, ["abc"], ["123"]).
+
 %% Flush DB
 eredis_cluster:flushdb().
 

VERSION

@@ -1 +1 @@
-0.5.6
+0.5.7

src/eredis_cluster.app.src

@@ -1,6 +1,6 @@
 {application, eredis_cluster, [
     {description, "Eredis Cluster"},
-    {vsn, "0.5.6"},
+    {vsn, "0.5.7"},
     {modules, []},
     {registered, []},
     {applications, [

src/eredis_cluster.erl

@@ -18,6 +18,7 @@
 -export([update_key/2]).
 -export([update_hash_field/3]).
 -export([optimistic_locking_transaction/3]).
+-export([eval/4]).
 
 -include("eredis_cluster.hrl").
 
@@ -81,26 +82,6 @@ transaction(Transaction, Slot, ExpectedValue, Counter) ->
             Payload
     end.
 
-%% =============================================================================
-%% @doc Wrapper function for command using pipelined commands
-%% @end
-%% =============================================================================
--spec qp(redis_pipeline_command()) -> redis_pipeline_result().
-qp(Commands) -> q(Commands).
-
-%% =============================================================================
-%% @doc This function execute simple or pipelined command on a single redis node
-%% the node will be automatically found according to the key used in the command
-%% @end
-%% =============================================================================
--spec q(redis_command()) -> redis_result().
-q(Command) ->
-    query(Command).
-
--spec qk(redis_command(), bitstring()) -> redis_result().
-qk(Command, PoolKey) ->
-    query(Command, PoolKey).
-
 %% =============================================================================
 %% @doc Multi node query
 %% @end
@@ -148,6 +129,26 @@ split_by_pools([], _Index, CmdAcc, MapAcc) ->
     MapAcc2 = [{Pool, lists:reverse(Mapping)} || {Pool, Mapping} <- MapAcc],
     {CmdAcc2, MapAcc2}.
 
+%% =============================================================================
+%% @doc Wrapper function for command using pipelined commands
+%% @end
+%% =============================================================================
+-spec qp(redis_pipeline_command()) -> redis_pipeline_result().
+qp(Commands) -> q(Commands).
+
+%% =============================================================================
+%% @doc This function execute simple or pipelined command on a single redis node
+%% the node will be automatically found according to the key used in the command
+%% @end
+%% =============================================================================
+-spec q(redis_command()) -> redis_result().
+q(Command) ->
+    query(Command).
+
+-spec qk(redis_command(), bitstring()) -> redis_result().
+qk(Command, PoolKey) ->
+    query(Command, PoolKey).
+
 query(Command) ->
     PoolKey = get_key_from_command(Command),
     query(Command, PoolKey).
@@ -269,6 +270,31 @@ optimistic_locking_transaction(WatchedKey, GetCommand, UpdateFunction) ->
             Error
     end.
 
+%% =============================================================================
+%% @doc Eval command helper, to optimize the query, it will try to execute the
+%% script using its hashed value. If no script is found, it will load it and
+%% try again.
+%% @end
+%% =============================================================================
+-spec eval(bitstring(), bitstring(), [bitstring()], [bitstring()]) ->
+    redis_result().
+eval(Script, ScriptHash, Keys, Args) ->
+    KeyNb = length(Keys),
+    EvalShaCommand = ["EVALSHA", ScriptHash, KeyNb] ++ Keys ++ Args,
+    Key = if
+        KeyNb == 0 -> "A"; %Random key
+        true -> hd(Keys)
+    end,
+
+    case qk(EvalShaCommand, Key) of
+        {error, <<"NOSCRIPT", _/binary>>} ->
+            LoadCommand = ["SCRIPT", "LOAD", Script],
+            [_, Result] = qk([LoadCommand, EvalShaCommand], Key),
+            Result;
+        Result ->
+            Result
+    end.
+
 %% =============================================================================
 %% @doc Perform a given query on all node of a redis cluster
 %% @end

test/eredis_cluster_tests.erl

@@ -140,6 +140,15 @@ basic_test_() ->
                 ?assertEqual([{<<"0">>,3},{<<"0">>,4},{<<"0">>,5},{<<"0">>,6},{<<"0">>,7}], lists:sort(IntermediateValues)),
                 ?assertEqual({ok, <<"7">>}, eredis_cluster:q(["hget", "klm", "nop"]))
             end
+            },
+
+            { "eval",
+            fun () ->
+                Script = <<"return redis.call('set', KEYS[1], ARGV[1]);">>,
+                ScriptHash = << << if N >= 10 -> N -10 + $a; true -> N + $0 end >> || <<N:4>> <= crypto:hash(sha, Script) >>,
+                eredis_cluster:eval(Script, ScriptHash, ["qrs"], ["evaltest"]),
+                ?assertEqual({ok, <<"evaltest">>}, eredis_cluster:q(["get", "qrs"]))
+            end
             }
 
       ]