From 535ba01a2586513c6ce23828382a980646934e1c Mon Sep 17 00:00:00 2001
From: Daiva Naudziuniene <daivan@fb.com>
Date: Mon, 30 Oct 2017 08:13:45 -0700
Subject: [PATCH] [LockConsistency] Model std::unique_lock::try_lock

Summary: `std::unique_lock` constructor allows to create a unique lock without locking the mutex. `std::unique_lock::try_lock` returns true if mutex has been acquired successfully, and false otherwise. It could be that an exception is being thrown while trying to acquire mutex, which is not modeled.

Reviewed By: jberdine

Differential Revision: D6185568

fbshipit-source-id: 192bf10
---
 infer/src/concurrency/RacerD.ml                      | 5 ++++-
 infer/tests/codetoanalyze/cpp/racerd/issues.exp      | 1 +
 infer/tests/codetoanalyze/cpp/racerd/unique_lock.cpp | 9 +++++++++
 3 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/infer/src/concurrency/RacerD.ml b/infer/src/concurrency/RacerD.ml
index ce99224d4..b815aef21 100644
--- a/infer/src/concurrency/RacerD.ml
+++ b/infer/src/concurrency/RacerD.ml
@@ -88,7 +88,10 @@ module TransferFunctions (CFG : ProcCfg.S) = struct
       fun pname ->
         QualifiedCppName.Match.match_qualifiers matcher (Typ.Procname.get_qualifiers pname)
     and is_cpp_trylock =
-      let matcher = QualifiedCppName.Match.of_fuzzy_qual_names ["std::unique_lock::owns_lock"] in
+      let matcher =
+        QualifiedCppName.Match.of_fuzzy_qual_names
+          ["std::unique_lock::owns_lock"; "std::unique_lock::try_lock"]
+      in
       fun pname ->
         QualifiedCppName.Match.match_qualifiers matcher (Typ.Procname.get_qualifiers pname)
     in
diff --git a/infer/tests/codetoanalyze/cpp/racerd/issues.exp b/infer/tests/codetoanalyze/cpp/racerd/issues.exp
index c12a10cac..391fcac19 100644
--- a/infer/tests/codetoanalyze/cpp/racerd/issues.exp
+++ b/infer/tests/codetoanalyze/cpp/racerd/issues.exp
@@ -13,3 +13,4 @@ codetoanalyze/cpp/racerd/unique_lock.cpp, basics::UniqueLock_get2, 4, LOCK_CONSI
 codetoanalyze/cpp/racerd/unique_lock.cpp, basics::UniqueLock_get4, 1, LOCK_CONSISTENCY_VIOLATION, [<Read trace>,access to `&this.suspiciously_read1`,<Write trace>,access to `&this.suspiciously_read1`]
 codetoanalyze/cpp/racerd/unique_lock.cpp, basics::UniqueLock_get4, 2, LOCK_CONSISTENCY_VIOLATION, [<Read trace>,access to `&this.suspiciously_read2`,<Write trace>,access to `&this.suspiciously_read2`]
 codetoanalyze/cpp/racerd/unique_lock.cpp, basics::UniqueLock_get5, 5, LOCK_CONSISTENCY_VIOLATION, [<Read trace>,access to `&this.suspiciously_read1`,<Write trace>,access to `&this.suspiciously_read1`]
+codetoanalyze/cpp/racerd/unique_lock.cpp, basics::UniqueLock_get6, 5, LOCK_CONSISTENCY_VIOLATION, [<Read trace>,access to `&this.suspiciously_read1`,<Write trace>,access to `&this.suspiciously_read1`]
diff --git a/infer/tests/codetoanalyze/cpp/racerd/unique_lock.cpp b/infer/tests/codetoanalyze/cpp/racerd/unique_lock.cpp
index c85ca1fb8..7a3d98874 100644
--- a/infer/tests/codetoanalyze/cpp/racerd/unique_lock.cpp
+++ b/infer/tests/codetoanalyze/cpp/racerd/unique_lock.cpp
@@ -67,6 +67,15 @@ class UniqueLock {
     }
   }
 
+  int get6() {
+    std::unique_lock<std::mutex> lock(mutex_, std::defer_lock);
+    if (lock.try_lock()) {
+      return well_guarded1;
+    } else {
+      return suspiciously_read1;
+    }
+  }
+
  private:
   int well_guarded1;
   int suspiciously_read1;