From 650ee014ec36850d031629c7ed35b67ac1e9e0ea Mon Sep 17 00:00:00 2001
From: Roman Mogilatov <rmogilatov@gmail.com>
Date: Fri, 4 Sep 2015 02:33:15 +0300
Subject: [PATCH] Implement thread-safety

---
 README.rst                       | 1 +
 VERSION                          | 2 +-
 dependency_injector/providers.py | 6 ++++--
 dependency_injector/utils.py     | 5 +++++
 docs/index.rst                   | 1 +
 docs/main/changelog.rst          | 4 ++++
 docs/providers/index.rst         | 3 +++
 7 files changed, 19 insertions(+), 3 deletions(-)

diff --git a/README.rst b/README.rst
index 9e2dbf45..a0186a95 100644
--- a/README.rst
+++ b/README.rst
@@ -39,6 +39,7 @@ framework:
 - Easy, smart, pythonic style.
 - Obvious, clear structure.
 - Memory efficiency.
+- Thread safety.
 - Semantic versioning.
 
 Main idea of *Dependency Injector* is to keep dependencies under control.
diff --git a/VERSION b/VERSION
index 2003b639..965065db 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-0.9.2
+0.9.3
diff --git a/dependency_injector/providers.py b/dependency_injector/providers.py
index 40d4ec4c..39b27476 100644
--- a/dependency_injector/providers.py
+++ b/dependency_injector/providers.py
@@ -9,6 +9,7 @@ from .utils import is_kwarg_injection
 from .utils import is_attribute_injection
 from .utils import is_method_injection
 from .utils import get_injectable_kwargs
+from .utils import GLOBAL_LOCK
 
 from .errors import Error
 
@@ -162,8 +163,9 @@ class Singleton(Provider):
 
     def _provide(self, *args, **kwargs):
         """Return provided instance."""
-        if not self._instance:
-            self._instance = self._factory(*args, **kwargs)
+        with GLOBAL_LOCK:
+            if not self._instance:
+                self._instance = self._factory(*args, **kwargs)
         return self._instance
 
     def reset(self):
diff --git a/dependency_injector/utils.py b/dependency_injector/utils.py
index f3ed3467..f737be81 100644
--- a/dependency_injector/utils.py
+++ b/dependency_injector/utils.py
@@ -1,10 +1,15 @@
 """Utils module."""
 
+import threading
+
 import six
 
 from .errors import Error
 
 
+GLOBAL_LOCK = threading.RLock()
+
+
 def is_provider(instance):
     """Check if instance is provider instance."""
     return (not isinstance(instance, six.class_types) and
diff --git a/docs/index.rst b/docs/index.rst
index 8ded4413..d4d648ed 100644
--- a/docs/index.rst
+++ b/docs/index.rst
@@ -39,6 +39,7 @@ framework:
 - Easy, smart, pythonic style.
 - Obvious, clear structure.
 - Memory efficiency.
+- Thread safety.
 - Semantic versioning.
 
 Main idea of *Dependency Injector* is to keep dependencies under control.
diff --git a/docs/main/changelog.rst b/docs/main/changelog.rst
index 550aac63..87e70504 100644
--- a/docs/main/changelog.rst
+++ b/docs/main/changelog.rst
@@ -13,6 +13,10 @@ Development version
 
 - No featues.
 
+0.9.3
+-----
+- Implement thread-safety.
+
 0.9.2
 -----
 - Add minor refactorings.
diff --git a/docs/providers/index.rst b/docs/providers/index.rst
index f5333c24..62c57abc 100644
--- a/docs/providers/index.rst
+++ b/docs/providers/index.rst
@@ -12,6 +12,9 @@ Current documentation section consists from description of standard providers
 library and some useful information like overriding of providers and writing 
 custom providers.
 
+All providers are validated in multithreading environment and considered to 
+be thread-safe.
+
 ..  toctree::
     :maxdepth: 2