[cost] Add naive model for forEach

Summary: We add a naive model for `forEach` idiom for Java's Iterable and Maps. The model is naive because it doesn't take the cost of the lambda into account. This will be fixed later.

Reviewed By: da319

Differential Revision: D23868203

fbshipit-source-id: 37d169c6f

infer/src/absint/PatternMatch.ml

@@ -102,6 +102,8 @@ module Java = struct
 
   let implements_arrays = implements "java.util.Arrays"
 
+  let implements_iterable = implements "java.lang.Iterable"
+
   let implements_iterator = implements "java.util.Iterator"
 
   let implements_collection = implements "java.util.Collection"

infer/src/absint/PatternMatch.mli

@@ -32,6 +32,9 @@ module Java : sig
   val implements_arrays : Tenv.t -> string -> bool
   (** Check whether class implements Java's Arrays *)
 
+  val implements_iterable : Tenv.t -> string -> bool
+  (** Check whether class implements Java's Iterable *)
+
   val implements_iterator : Tenv.t -> string -> bool
   (** Check whether class implements Java's Iterator *)
 

infer/src/cost/costModels.ml

@@ -269,6 +269,12 @@ module Call = struct
         ; +PatternMatch.Java.implements_collections
           &:: "copy" <>$ capt_exp
           $+...$--> BoundsOfCollection.linear_length ~of_function:"Collections.copy"
+          (* TODO: T72085946; take the cost of function into account *)
+        ; +PatternMatch.Java.implements_iterable
+          &:: "forEach" $ capt_exp
+          $+...$--> BoundsOfCollection.linear_length ~of_function:"Iterable.forEach"
+        ; +PatternMatch.Java.implements_map &:: "forEach" $ capt_exp
+          $+...$--> BoundsOfCollection.linear_length ~of_function:"Map.forEach"
         ; +PatternMatch.Java.implements_collections
           &:: "fill" <>$ capt_exp
           $+...$--> BoundsOfCollection.linear_length ~of_function:"Collections.fill"

infer/tests/codetoanalyze/java/performance/ForEachTest.java

@@ -0,0 +1,36 @@
+/*
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+import java.util.List;
+import java.util.Map;
+
+class ForEachTest {
+
+  int add(Integer x, Integer y) {
+    return x + y;
+  }
+
+  int loop_linear(Integer x, List<Integer> list) {
+    int sum = 0;
+    for (Integer el : list) {
+      sum = +el + x;
+    }
+    return sum;
+  }
+
+  void map_linear(Map<Integer, Integer> map) {
+    map.forEach((key, value) -> add(key, value));
+  }
+
+  void list_linear(List<Integer> myList) {
+    myList.forEach(el -> add(el, 1));
+  }
+
+  // FN: We have limited lambda support and canot incur costs of the lambda calls yet.
+  void list_quadratic_FN(List<Integer> myList) {
+    myList.forEach(el -> loop_linear(el, myList));
+  }
+}

infer/tests/codetoanalyze/java/performance/cost-issues.exp

@@ -183,6 +183,12 @@ codetoanalyze/java/performance/EvilCfg.java, EvilCfg.foo_FP(int,int,boolean):voi
 codetoanalyze/java/performance/FieldAccess.java, codetoanalyze.java.performance.FieldAccess$Test.<init>(codetoanalyze.java.performance.FieldAccess), 6,  OnUIThread:false, []
 codetoanalyze/java/performance/FieldAccess.java, codetoanalyze.java.performance.FieldAccess.<init>(), 3,  OnUIThread:false, []
 codetoanalyze/java/performance/FieldAccess.java, codetoanalyze.java.performance.FieldAccess.iterate_upto_field_size_linear(codetoanalyze.java.performance.FieldAccess$Test):void, 6 + 6 ⋅ test.a,  OnUIThread:false, [{test.a},Loop]
+codetoanalyze/java/performance/ForEachTest.java, ForEachTest.<init>(), 3,  OnUIThread:false, []
+codetoanalyze/java/performance/ForEachTest.java, ForEachTest.add(java.lang.Integer,java.lang.Integer):int, 10,  OnUIThread:false, []
+codetoanalyze/java/performance/ForEachTest.java, ForEachTest.list_linear(java.util.List):void, 12 + myList.length,  OnUIThread:false, [{myList.length},Modeled call to Iterable.forEach]
+codetoanalyze/java/performance/ForEachTest.java, ForEachTest.list_quadratic_FN(java.util.List):void, 22 + myList.length,  OnUIThread:false, [{myList.length},Modeled call to Iterable.forEach]
+codetoanalyze/java/performance/ForEachTest.java, ForEachTest.loop_linear(java.lang.Integer,java.util.List):int, 9 + 17 ⋅ list.length + 3 ⋅ (list.length + 1),  OnUIThread:false, [{list.length + 1},Loop,{list.length},Loop]
+codetoanalyze/java/performance/ForEachTest.java, ForEachTest.map_linear(java.util.Map):void, 12 + map.length,  OnUIThread:false, [{map.length},Modeled call to Map.forEach]
 codetoanalyze/java/performance/InferAnnotationTest.java, InferAnnotationTest.<init>(), 3,  OnUIThread:false, []
 codetoanalyze/java/performance/InferAnnotationTest.java, InferAnnotationTest.assert_get_list_constant():void, 81,  OnUIThread:false, []
 codetoanalyze/java/performance/InferAnnotationTest.java, InferAnnotationTest.assert_get_map_constant():void, 102,  OnUIThread:false, []