From: Andrii Grynenko <andrii@fb.com>
Date: Thu, 26 Nov 2015 20:33:16 +0000 (-0800)
Subject: Deprecate get_weak()
X-Git-Tag: deprecate-dynamic-initializer~223
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=19fb62bd3fa370bcecd3fac46910718e3871aec6;p=folly.git

Deprecate get_weak()

Summary: get_weak() is always used with .lock(), but try_get() is actually more performant than get_weak().lock().
Using get_weak() to store a weak_ptr and keep locking is not safe in fork scenarios.

Reviewed By: yfeldblum

Differential Revision: D2694223

fb-gh-sync-id: 908d44293ffd9b3782152d43e28d5de172d1654a
---

diff --git a/folly/Singleton.h b/folly/Singleton.h
index 94867c02..af8dacdb 100644
--- a/folly/Singleton.h
+++ b/folly/Singleton.h
@@ -486,7 +486,8 @@ class Singleton {
   // singleton, you can try to do so with a weak_ptr.  Avoid this when
   // possible but the inability to lock the weak pointer can be a
   // signal that the vault has been destroyed.
-  static std::weak_ptr<T> get_weak() {
+  static std::weak_ptr<T>
+  get_weak() __attribute__ ((__deprecated__("Replaced by try_get")))  {
     return getEntry().get_weak();
   }
 
diff --git a/folly/test/SingletonTest.cpp b/folly/test/SingletonTest.cpp
index 575e136f..89423d45 100644
--- a/folly/test/SingletonTest.cpp
+++ b/folly/test/SingletonTest.cpp
@@ -391,10 +391,10 @@ TEST(Singleton, SingletonCreationError) {
   SingletonCreationError<ErrorConstructor> error_once_singleton;
 
   // first time should error out
-  EXPECT_THROW(error_once_singleton.get_weak().lock(), std::runtime_error);
+  EXPECT_THROW(error_once_singleton.try_get(), std::runtime_error);
 
   // second time it'll work fine
-  error_once_singleton.get_weak().lock();
+  error_once_singleton.try_get();
   SUCCEED();
 }
 
@@ -409,7 +409,7 @@ TEST(Singleton, SingletonConcurrencyStress) {
   std::vector<std::thread> ts;
   for (size_t i = 0; i < 100; ++i) {
     ts.emplace_back([&]() {
-        slowpoke_singleton.get_weak().lock();
+        slowpoke_singleton.try_get();
       });
   }