8 files changed, 66 insertions, 35 deletions
diff --git a/googlemock/include/gmock/gmock-actions.h b/googlemock/include/gmock/gmock-actions.h
index e4af9d2d..d4af9490 100644
--- a/googlemock/include/gmock/gmock-actions.h
+++ b/googlemock/include/gmock/gmock-actions.h
@@ -42,7 +42,6 @@
 #endif
 
 #include <algorithm>
-#include <memory>
 #include <string>
 #include <utility>
 
@@ -347,7 +346,9 @@ class ActionInterface {
 // An Action<F> is a copyable and IMMUTABLE (except by assignment)
 // object that represents an action to be taken when a mock function
 // of type F is called.  The implementation of Action<T> is just a
-// std::shared_ptr to const ActionInterface<T>. Don't inherit from Action!
+// linked_ptr to const ActionInterface<T>, so copying is fairly cheap.
+// Don't inherit from Action!
+//
 // You can view an object implementing ActionInterface<F> as a
 // concrete action (including its current state), and an Action<F>
 // object as a handle to it.
@@ -424,7 +425,7 @@ class Action {
 #if GTEST_LANG_CXX11
   ::std::function<F> fun_;
 #endif
-  std::shared_ptr<ActionInterface<F>> impl_;
+  internal::linked_ptr<ActionInterface<F> > impl_;
 };
 
 // The PolymorphicAction class template makes it easy to implement a
@@ -518,7 +519,7 @@ class ActionAdaptor : public ActionInterface<F1> {
   }
 
  private:
-  const std::shared_ptr<ActionInterface<F2>> impl_;
+  const internal::linked_ptr<ActionInterface<F2> > impl_;
 
   GTEST_DISALLOW_ASSIGN_(ActionAdaptor);
 };
@@ -600,7 +601,7 @@ class ReturnAction {
     // Result to call.  ImplicitCast_ forces the compiler to convert R to
     // Result without considering explicit constructors, thus resolving the
     // ambiguity. value_ is then initialized using its copy constructor.
-    explicit Impl(const std::shared_ptr<R>& value)
+    explicit Impl(const linked_ptr<R>& value)
         : value_before_cast_(*value),
           value_(ImplicitCast_<Result>(value_before_cast_)) {}
 
@@ -625,7 +626,7 @@ class ReturnAction {
     typedef typename Function<F>::Result Result;
     typedef typename Function<F>::ArgumentTuple ArgumentTuple;
 
-    explicit Impl(const std::shared_ptr<R>& wrapper)
+    explicit Impl(const linked_ptr<R>& wrapper)
         : performed_(false), wrapper_(wrapper) {}
 
     virtual Result Perform(const ArgumentTuple&) {
@@ -637,12 +638,12 @@ class ReturnAction {
 
    private:
     bool performed_;
-    const std::shared_ptr<R> wrapper_;
+    const linked_ptr<R> wrapper_;
 
     GTEST_DISALLOW_ASSIGN_(Impl);
   };
 
-  const std::shared_ptr<R> value_;
+  const linked_ptr<R> value_;
 
   GTEST_DISALLOW_ASSIGN_(ReturnAction);
 };
@@ -865,7 +866,7 @@ class SetArgumentPointeeAction<N, Proto, true> {
   }
 
  private:
-  const std::shared_ptr<Proto> proto_;
+  const internal::linked_ptr<Proto> proto_;
 
   GTEST_DISALLOW_ASSIGN_(SetArgumentPointeeAction);
 };
@@ -930,7 +931,7 @@ class InvokeCallbackWithoutArgsAction {
   Result Perform(const ArgumentTuple&) const { return callback_->Run(); }
 
  private:
-  const std::shared_ptr<CallbackType> callback_;
+  const internal::linked_ptr<CallbackType> callback_;
 
   GTEST_DISALLOW_ASSIGN_(InvokeCallbackWithoutArgsAction);
 };
diff --git a/googlemock/include/gmock/gmock-cardinalities.h b/googlemock/include/gmock/gmock-cardinalities.h
index 8fa25ebb..f9169315 100644
--- a/googlemock/include/gmock/gmock-cardinalities.h
+++ b/googlemock/include/gmock/gmock-cardinalities.h
@@ -40,7 +40,6 @@
 #define GMOCK_INCLUDE_GMOCK_GMOCK_CARDINALITIES_H_
 
 #include <limits.h>
-#include <memory>
 #include <ostream>  // NOLINT
 #include "gmock/internal/gmock-port.h"
 #include "gtest/gtest.h"
@@ -82,8 +81,9 @@ class CardinalityInterface {
 
 // A Cardinality is a copyable and IMMUTABLE (except by assignment)
 // object that specifies how many times a mock function is expected to
-// be called.  The implementation of Cardinality is just a std::shared_ptr
-// to const CardinalityInterface. Don't inherit from Cardinality!
+// be called.  The implementation of Cardinality is just a linked_ptr
+// to const CardinalityInterface, so copying is fairly cheap.
+// Don't inherit from Cardinality!
 class GTEST_API_ Cardinality {
  public:
   // Constructs a null cardinality.  Needed for storing Cardinality
@@ -123,7 +123,7 @@ class GTEST_API_ Cardinality {
                                         ::std::ostream* os);
 
  private:
-  std::shared_ptr<const CardinalityInterface> impl_;
+  internal::linked_ptr<const CardinalityInterface> impl_;
 };
 
 // Creates a cardinality that allows at least n calls.
diff --git a/googlemock/include/gmock/gmock-generated-actions.h b/googlemock/include/gmock/gmock-generated-actions.h
index 8966f05c..0845b221 100644
--- a/googlemock/include/gmock/gmock-generated-actions.h
+++ b/googlemock/include/gmock/gmock-generated-actions.h
@@ -41,7 +41,6 @@
 #ifndef GMOCK_INCLUDE_GMOCK_GMOCK_GENERATED_ACTIONS_H_
 #define GMOCK_INCLUDE_GMOCK_GMOCK_GENERATED_ACTIONS_H_
 
-#include <memory>
 #include <utility>
 
 #include "gmock/gmock-actions.h"
@@ -349,7 +348,7 @@ class InvokeCallbackAction {
         callback_.get(), args);
   }
  private:
-  const std::shared_ptr<CallbackType> callback_;
+  const linked_ptr<CallbackType> callback_;
 };
 
 // An INTERNAL macro for extracting the type of a tuple field.  It's
diff --git a/googlemock/include/gmock/gmock-generated-actions.h.pump b/googlemock/include/gmock/gmock-generated-actions.h.pump
index 09a39ca8..bc22be8e 100644
--- a/googlemock/include/gmock/gmock-generated-actions.h.pump
+++ b/googlemock/include/gmock/gmock-generated-actions.h.pump
@@ -43,7 +43,6 @@ $$}} This meta comment fixes auto-indentation in editors.
 #ifndef GMOCK_INCLUDE_GMOCK_GMOCK_GENERATED_ACTIONS_H_
 #define GMOCK_INCLUDE_GMOCK_GMOCK_GENERATED_ACTIONS_H_
 
-#include <memory>
 #include <utility>
 
 #include "gmock/gmock-actions.h"
@@ -119,7 +118,7 @@ class InvokeCallbackAction {
         callback_.get(), args);
   }
  private:
-  const std::shared_ptr<CallbackType> callback_;
+  const linked_ptr<CallbackType> callback_;
 };
 
 // An INTERNAL macro for extracting the type of a tuple field.  It's
diff --git a/googlemock/include/gmock/gmock-matchers.h b/googlemock/include/gmock/gmock-matchers.h
index 95bc22c5..6e8bc036 100644
--- a/googlemock/include/gmock/gmock-matchers.h
+++ b/googlemock/include/gmock/gmock-matchers.h
@@ -43,15 +43,14 @@
 #include <algorithm>
 #include <iterator>
 #include <limits>
-#include <memory>
 #include <ostream>  // NOLINT
 #include <sstream>
 #include <string>
 #include <utility>
 #include <vector>
+#include "gtest/gtest.h"
 #include "gmock/internal/gmock-internal-utils.h"
 #include "gmock/internal/gmock-port.h"
-#include "gtest/gtest.h"
 
 #if GTEST_HAS_STD_INITIALIZER_LIST_
 # include <initializer_list>  // NOLINT -- must be after gtest.h
@@ -339,15 +338,29 @@ class MatcherBase {
   virtual ~MatcherBase() {}
 
  private:
-  std::shared_ptr<const MatcherInterface<GTEST_REFERENCE_TO_CONST_(T)>> impl_;
+  // shared_ptr (util/gtl/shared_ptr.h) and linked_ptr have similar
+  // interfaces.  The former dynamically allocates a chunk of memory
+  // to hold the reference count, while the latter tracks all
+  // references using a circular linked list without allocating
+  // memory.  It has been observed that linked_ptr performs better in
+  // typical scenarios.  However, shared_ptr can out-perform
+  // linked_ptr when there are many more uses of the copy constructor
+  // than the default constructor.
+  //
+  // If performance becomes a problem, we should see if using
+  // shared_ptr helps.
+  ::testing::internal::linked_ptr<
+      const MatcherInterface<GTEST_REFERENCE_TO_CONST_(T)> >
+      impl_;
 };
 
 }  // namespace internal
 
 // A Matcher<T> is a copyable and IMMUTABLE (except by assignment)
 // object that can check whether a value of type T matches.  The
-// implementation of Matcher<T> is just a std::shared_ptr to const
-// MatcherInterface<T>.  Don't inherit from Matcher!
+// implementation of Matcher<T> is just a linked_ptr to const
+// MatcherInterface<T>, so copying is fairly cheap.  Don't inherit
+// from Matcher!
 template <typename T>
 class Matcher : public internal::MatcherBase<T> {
  public:
@@ -1573,7 +1586,7 @@ class MatchesRegexMatcher {
   }
 
  private:
-  const std::shared_ptr<const RE> regex_;
+  const internal::linked_ptr<const RE> regex_;
   const bool full_match_;
 
   GTEST_DISALLOW_ASSIGN_(MatchesRegexMatcher);
diff --git a/googlemock/include/gmock/gmock-spec-builders.h b/googlemock/include/gmock/gmock-spec-builders.h
index 7759cb35..5d4b73ba 100644
--- a/googlemock/include/gmock/gmock-spec-builders.h
+++ b/googlemock/include/gmock/gmock-spec-builders.h
@@ -62,7 +62,6 @@
 #define GMOCK_INCLUDE_GMOCK_GMOCK_SPEC_BUILDERS_H_
 
 #include <map>
-#include <memory>
 #include <set>
 #include <sstream>
 #include <string>
@@ -220,7 +219,8 @@ class GTEST_API_ UntypedFunctionMockerBase {
  protected:
   typedef std::vector<const void*> UntypedOnCallSpecs;
 
-  using UntypedExpectations = std::vector<std::shared_ptr<ExpectationBase>>;
+  typedef std::vector<internal::linked_ptr<ExpectationBase> >
+  UntypedExpectations;
 
   // Returns an Expectation object that references and co-owns exp,
   // which must be an expectation on this mock function.
@@ -498,7 +498,12 @@ class GTEST_API_ Mock {
 //   - Constness is shallow: a const Expectation object itself cannot
 //     be modified, but the mutable methods of the ExpectationBase
 //     object it references can be called via expectation_base().
-
+//   - The constructors and destructor are defined out-of-line because
+//     the Symbian WINSCW compiler wants to otherwise instantiate them
+//     when it sees this class definition, at which point it doesn't have
+//     ExpectationBase available yet, leading to incorrect destruction
+//     in the linked_ptr (or compilation errors if using a checking
+//     linked_ptr).
 class GTEST_API_ Expectation {
  public:
   // Constructs a null object that doesn't reference any expectation.
@@ -550,15 +555,16 @@ class GTEST_API_ Expectation {
   typedef ::std::set<Expectation, Less> Set;
 
   Expectation(
-      const std::shared_ptr<internal::ExpectationBase>& expectation_base);
+      const internal::linked_ptr<internal::ExpectationBase>& expectation_base);
 
   // Returns the expectation this object references.
-  const std::shared_ptr<internal::ExpectationBase>& expectation_base() const {
+  const internal::linked_ptr<internal::ExpectationBase>&
+  expectation_base() const {
     return expectation_base_;
   }
 
-  // A shared_ptr that co-owns the expectation this handle references.
-  std::shared_ptr<internal::ExpectationBase> expectation_base_;
+  // A linked_ptr that co-owns the expectation this handle references.
+  internal::linked_ptr<internal::ExpectationBase> expectation_base_;
 };
 
 // A set of expectation handles.  Useful in the .After() clause of
@@ -640,8 +646,11 @@ class GTEST_API_ Sequence {
   void AddExpectation(const Expectation& expectation) const;
 
  private:
-  // The last expectation in this sequence.
-  std::shared_ptr<Expectation> last_expectation_;
+  // The last expectation in this sequence.  We use a linked_ptr here
+  // because Sequence objects are copyable and we want the copies to
+  // be aliases.  The linked_ptr allows the copies to co-own and share
+  // the same Expectation object.
+  internal::linked_ptr<Expectation> last_expectation_;
 };  // class Sequence
 
 // An object of this type causes all EXPECT_CALL() statements
@@ -864,7 +873,7 @@ class GTEST_API_ ExpectationBase {
   Cardinality cardinality_;            // The cardinality of the expectation.
   // The immediate pre-requisites (i.e. expectations that must be
   // satisfied before this expectation can be matched) of this
-  // expectation.  We use std::shared_ptr in the set because we want an
+  // expectation.  We use linked_ptr in the set because we want an
   // Expectation object to be co-owned by its FunctionMocker and its
   // successors.  This allows multiple mock objects to be deleted at
   // different times.
@@ -1622,7 +1631,7 @@ class FunctionMockerBase : public UntypedFunctionMockerBase {
     Mock::RegisterUseByOnCallOrExpectCall(MockObject(), file, line);
     TypedExpectation<F>* const expectation =
         new TypedExpectation<F>(this, file, line, source_text, m);
-    const std::shared_ptr<ExpectationBase> untyped_expectation(expectation);
+    const linked_ptr<ExpectationBase> untyped_expectation(expectation);
     // See the definition of untyped_expectations_ for why access to
     // it is unprotected here.
     untyped_expectations_.push_back(untyped_expectation);
diff --git a/googlemock/include/gmock/internal/gmock-internal-utils.h b/googlemock/include/gmock/internal/gmock-internal-utils.h
index 7514635e..fd33c004 100644
--- a/googlemock/include/gmock/internal/gmock-internal-utils.h
+++ b/googlemock/include/gmock/internal/gmock-internal-utils.h
@@ -92,6 +92,15 @@ inline const typename Pointer::element_type* GetRawPointer(const Pointer& p) {
 template <typename Element>
 inline Element* GetRawPointer(Element* p) { return p; }
 
+// This comparator allows linked_ptr to be stored in sets.
+template <typename T>
+struct LinkedPtrLessThan {
+  bool operator()(const ::testing::internal::linked_ptr<T>& lhs,
+                  const ::testing::internal::linked_ptr<T>& rhs) const {
+    return lhs.get() < rhs.get();
+  }
+};
+
 // Symbian compilation can be done with wchar_t being either a native
 // type or a typedef.  Using Google Mock with OpenC without wchar_t
 // should require the definition of _STLP_NO_WCHAR_T.
diff --git a/googlemock/include/gmock/internal/gmock-port.h b/googlemock/include/gmock/internal/gmock-port.h
index c5932493..fda27dba 100644
--- a/googlemock/include/gmock/internal/gmock-port.h
+++ b/googlemock/include/gmock/internal/gmock-port.h
@@ -52,6 +52,7 @@
 // here, as Google Mock depends on Google Test.  Only add a utility
 // here if it's truly specific to Google Mock.
 
+#include "gtest/internal/gtest-linked_ptr.h"
 #include "gtest/internal/gtest-port.h"
 #include "gmock/internal/custom/gmock-port.h"