SERVER-33437 Make Decorables not type-erased.

The current Decorable system type-erases the most derived (Decorated)
type when registering Decorations.  This is illegal as derived classes
which are no longer standard-layout can have the `Decorable` base
class reordered with respect to the base address of their storage.

This also removes the "with-owner" forms of declaring a decoration,
which caused problems with layout.  The decoration handles have
been modified to provide mechanisms to get back to the owner
directly, given a pointer or reference to the decoration.

20 files changed, 215 insertions, 258 deletions

diff --git a/src/mongo/db/SConscript b/src/mongo/db/SConscript
index 7ac4aa70a8b..b9cb84dac26 100644
--- a/src/mongo/db/SConscript
+++ b/src/mongo/db/SConscript
@@ -479,7 +479,6 @@ env.Library(
         '$BUILD_DIR/mongo/transport/transport_layer_common',
         '$BUILD_DIR/mongo/util/clock_sources',
         '$BUILD_DIR/mongo/util/concurrency/spin_lock',
-        '$BUILD_DIR/mongo/util/decorable',
         '$BUILD_DIR/mongo/util/fail_point',
         '$BUILD_DIR/mongo/util/net/host',
         '$BUILD_DIR/mongo/util/periodic_runner',
@@ -653,7 +652,6 @@ env.Library(
     ],
     LIBDEPS=[
         '$BUILD_DIR/mongo/base',
-        '$BUILD_DIR/mongo/util/decorable',
     ],
 )
 
diff --git a/src/mongo/db/auth/SConscript b/src/mongo/db/auth/SConscript
index 5827aa592d1..d36b1854c14 100644
--- a/src/mongo/db/auth/SConscript
+++ b/src/mongo/db/auth/SConscript
@@ -23,7 +23,6 @@ env.Library(
     ],
     LIBDEPS = [
         '$BUILD_DIR/mongo/base',
-        '$BUILD_DIR/mongo/util/decorable',
         '$BUILD_DIR/mongo/util/net/network',
     ],
 )
diff --git a/src/mongo/db/catalog/SConscript b/src/mongo/db/catalog/SConscript
index db9f6516cfa..3ba44290c72 100644
--- a/src/mongo/db/catalog/SConscript
+++ b/src/mongo/db/catalog/SConscript
@@ -219,7 +219,6 @@ env.Library(
         '$BUILD_DIR/mongo/base',
         '$BUILD_DIR/mongo/db/namespace_string',
         '$BUILD_DIR/mongo/db/storage/storage_options',
-        '$BUILD_DIR/mongo/util/decorable',
     ],
 )
 
diff --git a/src/mongo/db/concurrency/SConscript b/src/mongo/db/concurrency/SConscript
index b14ddc7e836..41c5abace77 100644
--- a/src/mongo/db/concurrency/SConscript
+++ b/src/mongo/db/concurrency/SConscript
@@ -42,7 +42,6 @@ env.Library(
     LIBDEPS=[
         '$BUILD_DIR/mongo/base',
         '$BUILD_DIR/mongo/util/background_job',
-        '$BUILD_DIR/mongo/util/decorable',
 
         # Temporary crutch since the ssl cleanup is hard coded in background.cpp
         '$BUILD_DIR/mongo/db/server_parameters',
diff --git a/src/mongo/db/repl/SConscript b/src/mongo/db/repl/SConscript
index 0f13e84726f..a8df37f3436 100644
--- a/src/mongo/db/repl/SConscript
+++ b/src/mongo/db/repl/SConscript
@@ -229,7 +229,6 @@ env.Library(
     LIBDEPS=[
         'optime',
         '$BUILD_DIR/mongo/db/service_context',
-        '$BUILD_DIR/mongo/util/decorable',
     ],
 )
 
@@ -343,7 +342,6 @@ env.Library(
         'rollback_idl',
         'storage_interface',
         '$BUILD_DIR/mongo/db/service_context',
-        '$BUILD_DIR/mongo/util/decorable',
     ],
 )
 
@@ -372,7 +370,6 @@ env.Library(
         '$BUILD_DIR/mongo/base',
         '$BUILD_DIR/mongo/db/namespace_string',
         '$BUILD_DIR/mongo/db/service_context',
-        '$BUILD_DIR/mongo/util/decorable',
     ],
 )
 
@@ -951,7 +948,6 @@ env.Library(
         '$BUILD_DIR/mongo/db/namespace_string',
         '$BUILD_DIR/mongo/db/service_context',
         '$BUILD_DIR/mongo/util/net/network',
-        '$BUILD_DIR/mongo/util/decorable',
     ],
 )
 
@@ -1325,7 +1321,6 @@ env.Library(
         '$BUILD_DIR/mongo/db/service_context',
         '$BUILD_DIR/mongo/unittest/concurrency',
         '$BUILD_DIR/mongo/unittest/unittest',
-        '$BUILD_DIR/mongo/util/decorable',
     ],
 )
 
diff --git a/src/mongo/db/s/SConscript b/src/mongo/db/s/SConscript
index cda73aa0065..da09c41fdf2 100644
--- a/src/mongo/db/s/SConscript
+++ b/src/mongo/db/s/SConscript
@@ -16,7 +16,6 @@ env.Library(
     ],
     LIBDEPS=[
         '$BUILD_DIR/mongo/base',
-        '$BUILD_DIR/mongo/util/decorable',
         '$BUILD_DIR/mongo/db/range_arithmetic',
         '$BUILD_DIR/mongo/s/sharding_routing_table',
     ],
diff --git a/src/mongo/db/s/database_sharding_state.cpp b/src/mongo/db/s/database_sharding_state.cpp
index 40a630bc5b4..952fd1c3695 100644
--- a/src/mongo/db/s/database_sharding_state.cpp
+++ b/src/mongo/db/s/database_sharding_state.cpp
@@ -34,12 +34,12 @@
 
 namespace mongo {
 const Database::Decoration<DatabaseShardingState> DatabaseShardingState::get =
-    Database::declareDecorationWithOwner<DatabaseShardingState>();
+    Database::declareDecoration<DatabaseShardingState>();
 
-DatabaseShardingState::DatabaseShardingState(Database* db) : _db(db) {}
+DatabaseShardingState::DatabaseShardingState() = default;
 
 void DatabaseShardingState::enterCriticalSection(OperationContext* opCtx) {
-    invariant(opCtx->lockState()->isDbLockedForMode(_db->name(), MODE_X));
+    invariant(opCtx->lockState()->isDbLockedForMode(get.owner(this)->name(), MODE_X));
     invariant(!_critSecSignal);
     _critSecSignal = std::make_shared<Notification<void>>();
     // TODO (SERVER-33313): call CursorManager::invalidateAll() on all collections in this database
@@ -49,7 +49,7 @@ void DatabaseShardingState::enterCriticalSection(OperationContext* opCtx) {
 
 void DatabaseShardingState::exitCriticalSection(OperationContext* opCtx,
                                                 boost::optional<DatabaseVersion> newDbVersion) {
-    invariant(opCtx->lockState()->isDbLockedForMode(_db->name(), MODE_X));
+    invariant(opCtx->lockState()->isDbLockedForMode(get.owner(this)->name(), MODE_X));
     invariant(_critSecSignal);
     _critSecSignal->set();
     _critSecSignal.reset();
@@ -62,7 +62,7 @@ std::shared_ptr<Notification<void>> DatabaseShardingState::getCriticalSectionSig
 
 void DatabaseShardingState::setDbVersion(OperationContext* opCtx,
                                          boost::optional<DatabaseVersion> newDbVersion) {
-    invariant(opCtx->lockState()->isDbLockedForMode(_db->name(), MODE_X));
+    invariant(opCtx->lockState()->isDbLockedForMode(get.owner(this)->name(), MODE_X));
     _dbVersion = newDbVersion;
 }
 
diff --git a/src/mongo/db/s/database_sharding_state.h b/src/mongo/db/s/database_sharding_state.h
index 28c0d94df22..50e6e0239eb 100644
--- a/src/mongo/db/s/database_sharding_state.h
+++ b/src/mongo/db/s/database_sharding_state.h
@@ -45,7 +45,7 @@ class DatabaseShardingState {
 public:
     static const Database::Decoration<DatabaseShardingState> get;
 
-    DatabaseShardingState(Database* db);
+    DatabaseShardingState();
     ~DatabaseShardingState() = default;
 
     /**
@@ -84,9 +84,6 @@ public:
     void checkDbVersion(OperationContext* opCtx) const;
 
 private:
-    // The database to which this sharding state corresponds.
-    const Database* _db;
-
     // Modifying the state below requires holding the DBLock in X mode; holding the DBLock in any
     // mode is acceptable for reading it. (Note: accessing this class at all requires holding the
     // DBLock in some mode, since it requires having a pointer to the Database).
diff --git a/src/mongo/db/storage/mmap_v1/SConscript b/src/mongo/db/storage/mmap_v1/SConscript
index 8ec5003fd68..eaa8da9a00b 100644
--- a/src/mongo/db/storage/mmap_v1/SConscript
+++ b/src/mongo/db/storage/mmap_v1/SConscript
@@ -239,7 +239,6 @@ if mmapv1:
         source=['record_store_v1_simple_test.cpp',
                 ],
         LIBDEPS=[
-            '$BUILD_DIR/mongo/util/decorable',
             'record_store_v1_test_help'
             ]
         )
@@ -249,7 +248,6 @@ if mmapv1:
         source=['record_store_v1_capped_test.cpp',
                 ],
         LIBDEPS=[
-            '$BUILD_DIR/mongo/util/decorable',
             'record_store_v1_test_help'
             ]
         )
@@ -282,7 +280,6 @@ if mmapv1:
         source=['btree/btree_logic_test.cpp'
                 ],
         LIBDEPS=[
-            '$BUILD_DIR/mongo/util/decorable',
             'btree_test_help'
             ]
         )
diff --git a/src/mongo/rpc/SConscript b/src/mongo/rpc/SConscript
index 98ea0e6d64c..c3b364020a7 100644
--- a/src/mongo/rpc/SConscript
+++ b/src/mongo/rpc/SConscript
@@ -150,7 +150,6 @@ env.Clone().InjectModule("enterprise").Library(
         '$BUILD_DIR/mongo/db/logical_time_validator',
         '$BUILD_DIR/mongo/db/repl/optime',
         '$BUILD_DIR/mongo/db/signed_logical_time',
-        '$BUILD_DIR/mongo/util/decorable',
     ],
 )
 
@@ -225,7 +224,6 @@ env.Library(
         '$BUILD_DIR/mongo/s/is_mongos',
         '$BUILD_DIR/mongo/transport/transport_layer',
         "$BUILD_DIR/mongo/util/concurrency/spin_lock",
-        '$BUILD_DIR/mongo/util/decorable',
         '$BUILD_DIR/mongo/util/net/network',
         "$BUILD_DIR/mongo/util/processinfo",
     ],
diff --git a/src/mongo/s/SConscript b/src/mongo/s/SConscript
index 83c784ff0be..7339848dac1 100644
--- a/src/mongo/s/SConscript
+++ b/src/mongo/s/SConscript
@@ -355,7 +355,6 @@ env.Library(
     LIBDEPS=[
         '$BUILD_DIR/mongo/base',
         '$BUILD_DIR/mongo/client/connection_string',
-        '$BUILD_DIR/mongo/util/decorable',
     ]
 )
 
diff --git a/src/mongo/transport/SConscript b/src/mongo/transport/SConscript
index f5cce983eac..6caf11beb61 100644
--- a/src/mongo/transport/SConscript
+++ b/src/mongo/transport/SConscript
@@ -13,7 +13,6 @@ env.Library(
     ],
     LIBDEPS=[
         '$BUILD_DIR/mongo/base',
-        '$BUILD_DIR/mongo/util/decorable',
     ],
 )
 
@@ -176,7 +175,6 @@ env.CppUnitTest(
         '$BUILD_DIR/mongo/rpc/command_request',
         '$BUILD_DIR/mongo/unittest/unittest',
         '$BUILD_DIR/mongo/util/clock_source_mock',
-        '$BUILD_DIR/mongo/util/decorable',
     ],
 )
 
@@ -193,7 +191,6 @@ zlibEnv.Library(
     ],
     LIBDEPS=[
         '$BUILD_DIR/mongo/base',
-        '$BUILD_DIR/mongo/util/decorable',
         '$BUILD_DIR/mongo/util/options_parser/options_parser',
         '$BUILD_DIR/third_party/shim_snappy',
         '$BUILD_DIR/third_party/shim_zlib',
diff --git a/src/mongo/util/SConscript b/src/mongo/util/SConscript
index dbac968868e..dc46c7a6fa9 100644
--- a/src/mongo/util/SConscript
+++ b/src/mongo/util/SConscript
@@ -59,22 +59,12 @@ debuggerEnv.Library(
     ]
 )
 
-env.Library(
-    target='decorable',
-    source=[
-        'decoration_container.cpp',
-        'decoration_registry.cpp',
-    ],
-    LIBDEPS=[]
-    )
-
 env.CppUnitTest(
     target='decorable_test',
     source=[
         'decorable_test.cpp'
         ],
     LIBDEPS=[
-        'decorable',
         ]
     )
 
diff --git a/src/mongo/util/decorable.h b/src/mongo/util/decorable.h
index 0545ec2f6ae..2589fac0262 100644
--- a/src/mongo/util/decorable.h
+++ b/src/mongo/util/decorable.h
@@ -59,7 +59,6 @@
 
 #pragma once
 
-#include "mongo/base/disallow_copying.h"
 #include "mongo/util/decoration_container.h"
 #include "mongo/util/decoration_registry.h"
 
@@ -67,7 +66,8 @@ namespace mongo {
 
 template <typename D>
 class Decorable {
-    MONGO_DISALLOW_COPYING(Decorable);
+    Decorable(const Decorable&) = delete;
+    Decorable& operator=(const Decorable&) = delete;
 
 public:
     template <typename T>
@@ -76,51 +76,72 @@ public:
         Decoration() = delete;
 
         T& operator()(D& d) const {
-            return static_cast<Decorable&>(d)._decorations.getDecoration(_raw);
+            return static_cast<Decorable&>(d)._decorations.getDecoration(this->_raw);
         }
 
-        T& operator()(D* d) const {
+        T& operator()(D* const d) const {
             return (*this)(*d);
         }
 
         const T& operator()(const D& d) const {
-            return static_cast<const Decorable&>(d)._decorations.getDecoration(_raw);
+            return static_cast<const Decorable&>(d)._decorations.getDecoration(this->_raw);
         }
 
-        const T& operator()(const D* d) const {
+        const T& operator()(const D* const d) const {
             return (*this)(*d);
         }
 
+        const D* owner(const T* const t) const {
+            return static_cast<const D*>(getOwnerImpl(t));
+        }
+
+        D* owner(T* const t) const {
+            return static_cast<D*>(getOwnerImpl(t));
+        }
+
+        const D& owner(const T& t) const {
+            return *owner(&t);
+        }
+
+        D& owner(T& t) const {
+            return *owner(&t);
+        }
+
     private:
+        const Decorable* getOwnerImpl(const T* const t) const {
+            return *reinterpret_cast<const Decorable* const*>(
+                reinterpret_cast<const unsigned char* const>(t) - _raw._raw._index);
+        }
+
+        Decorable* getOwnerImpl(T* const t) const {
+            return const_cast<Decorable*>(getOwnerImpl(const_cast<const T*>(t)));
+        }
+
         friend class Decorable;
 
-        explicit Decoration(DecorationContainer::DecorationDescriptorWithType<T> raw)
+        explicit Decoration(
+            typename DecorationContainer<D>::template DecorationDescriptorWithType<T> raw)
             : _raw(std::move(raw)) {}
 
-        DecorationContainer::DecorationDescriptorWithType<T> _raw;
+        typename DecorationContainer<D>::template DecorationDescriptorWithType<T> _raw;
     };
 
     template <typename T>
     static Decoration<T> declareDecoration() {
-        return Decoration<T>(getRegistry()->declareDecoration<T>());
-    }
-
-    template <typename T>
-    static Decoration<T> declareDecorationWithOwner() {
-        return Decoration<T>(getRegistry()->declareDecorationWithOwner<T, D>());
+        return Decoration<T>(getRegistry()->template declareDecoration<T>());
     }
 
 protected:
-    Decorable() : _decorations(getRegistry(), this) {}
+    Decorable() : _decorations(this, getRegistry()) {}
     ~Decorable() = default;
 
 private:
-    static DecorationRegistry* getRegistry() {
-        static DecorationRegistry* theRegistry = new DecorationRegistry();
+    static DecorationRegistry<D>* getRegistry() {
+        static DecorationRegistry<D>* theRegistry = new DecorationRegistry<D>();
         return theRegistry;
     }
 
-    DecorationContainer _decorations;
+    DecorationContainer<D> _decorations;
 };
 
 }  // namespace mongo
diff --git a/src/mongo/util/decorable_test.cpp b/src/mongo/util/decorable_test.cpp
index 356cc9cfb64..8f075a9ec87 100644
--- a/src/mongo/util/decorable_test.cpp
+++ b/src/mongo/util/decorable_test.cpp
@@ -65,8 +65,9 @@ public:
     int value;
 };
 
+class MyDecorable : public Decorable<MyDecorable> {};
+
 TEST(DecorableTest, DecorableType) {
-    class MyDecorable : public Decorable<MyDecorable> {};
     const auto dd1 = MyDecorable::declareDecoration<A>();
     const auto dd2 = MyDecorable::declareDecoration<A>();
     const auto dd3 = MyDecorable::declareDecoration<int>();
@@ -102,16 +103,16 @@ TEST(DecorableTest, DecorableType) {
 TEST(DecorableTest, SimpleDecoration) {
     numConstructedAs = 0;
     numDestructedAs = 0;
-    DecorationRegistry registry;
+    DecorationRegistry<MyDecorable> registry;
     const auto dd1 = registry.declareDecoration<A>();
     const auto dd2 = registry.declareDecoration<A>();
     const auto dd3 = registry.declareDecoration<int>();
 
     {
-        DecorationContainer decorable1(&registry, nullptr);
+        DecorationContainer<MyDecorable> decorable1(nullptr, &registry);
         ASSERT_EQ(2, numConstructedAs);
         ASSERT_EQ(0, numDestructedAs);
-        DecorationContainer decorable2(&registry, nullptr);
+        DecorationContainer<MyDecorable> decorable2(nullptr, &registry);
         ASSERT_EQ(4, numConstructedAs);
         ASSERT_EQ(0, numDestructedAs);
 
@@ -138,13 +139,13 @@ TEST(DecorableTest, ThrowingConstructor) {
     numConstructedAs = 0;
     numDestructedAs = 0;
 
-    DecorationRegistry registry;
+    DecorationRegistry<MyDecorable> registry;
     registry.declareDecoration<A>();
     registry.declareDecoration<ThrowA>();
     registry.declareDecoration<A>();
 
     try {
-        DecorationContainer d(&registry, nullptr);
+        DecorationContainer<MyDecorable> d(nullptr, &registry);
     } catch (const AssertionException& ex) {
         ASSERT_EQ(ErrorCodes::Unauthorized, ex.code());
     }
@@ -153,12 +154,12 @@ TEST(DecorableTest, ThrowingConstructor) {
 }
 
 TEST(DecorableTest, Alignment) {
-    DecorationRegistry registry;
+    DecorationRegistry<MyDecorable> registry;
     const auto firstChar = registry.declareDecoration<char>();
     const auto firstInt = registry.declareDecoration<int>();
     const auto secondChar = registry.declareDecoration<int>();
     const auto secondInt = registry.declareDecoration<int>();
-    DecorationContainer d(&registry, nullptr);
+    DecorationContainer<MyDecorable> d(nullptr, &registry);
     ASSERT_EQ(0U,
               reinterpret_cast<uintptr_t>(&d.getDecoration(firstChar)) %
                   std::alignment_of<char>::value);
@@ -173,19 +174,69 @@ TEST(DecorableTest, Alignment) {
                   std::alignment_of<int>::value);
 }
 
+struct DecoratedOwnerChecker : public Decorable<DecoratedOwnerChecker> {
+    const char answer[100] = "The answer to life the universe and everything is 42";
+};
 
-class MyDecorable : public Decorable<MyDecorable> {};
+// Test all 4 variations of the owner back reference: const pointer, non-const pointer, const
+// reference, non-const reference.
+struct DecorationWithOwner {
+    DecorationWithOwner() {}
 
-class ClassWithOwnerPtr {
-public:
-    ClassWithOwnerPtr(MyDecorable* decorable) : owner(decorable) {}
-    MyDecorable* owner;
+    static const DecoratedOwnerChecker::Decoration<DecorationWithOwner> get;
+
+    std::string getTheAnswer1() const {
+        // const pointer variant
+        auto* const owner = get.owner(this);
+        static_assert(std::is_same<const DecoratedOwnerChecker* const, decltype(owner)>::value,
+                      "Type of fetched owner pointer is incorrect.");
+        return owner->answer;
+    }
+
+    std::string getTheAnswer2() {
+        // non-const pointer variant
+        DecoratedOwnerChecker* const owner = get.owner(this);
+        return owner->answer;
+    }
+
+    std::string getTheAnswer3() const {
+        // const reference variant
+        auto& owner = get.owner(*this);
+        static_assert(std::is_same<const DecoratedOwnerChecker&, decltype(owner)>::value,
+                      "Type of fetched owner reference is incorrect.");
+        return owner.answer;
+    }
+
+    std::string getTheAnswer4() {
+        // Non-const reference variant
+        DecoratedOwnerChecker& owner = get.owner(*this);
+        return owner.answer;
+    }
 };
 
+const DecoratedOwnerChecker::Decoration<DecorationWithOwner> DecorationWithOwner::get =
+    DecoratedOwnerChecker::declareDecoration<DecorationWithOwner>();
+
+
 TEST(DecorableTest, DecorationWithOwner) {
-    const auto get = MyDecorable::declareDecorationWithOwner<ClassWithOwnerPtr>();
-    MyDecorable decorable;
-    invariant(get(decorable).owner == &decorable);
+    DecoratedOwnerChecker owner;
+    const std::string answer = owner.answer;
+    ASSERT_NE(answer, "");
+
+    const std::string witness1 = DecorationWithOwner::get(owner).getTheAnswer1();
+    ASSERT_EQ(answer, witness1);
+
+    const std::string witness2 = DecorationWithOwner::get(owner).getTheAnswer2();
+    ASSERT_EQ(answer, witness2);
+
+    const std::string witness3 = DecorationWithOwner::get(owner).getTheAnswer3();
+    ASSERT_EQ(answer, witness3);
+
+    const std::string witness4 = DecorationWithOwner::get(owner).getTheAnswer4();
+    ASSERT_EQ(answer, witness4);
+
+    DecorationWithOwner& decoration = DecorationWithOwner::get(owner);
+    ASSERT_EQ(&owner, &DecorationWithOwner::get.owner(decoration));
 }
 
 }  // namespace
diff --git a/src/mongo/util/decoration_container.cpp b/src/mongo/util/decoration_container.cpp
deleted file mode 100644
index b78cdd92bac..00000000000
--- a/src/mongo/util/decoration_container.cpp
+++ /dev/null
@@ -1,47 +0,0 @@
-/**
- *    Copyright (C) 2015 MongoDB Inc.
- *
- *    This program is free software: you can redistribute it and/or  modify
- *    it under the terms of the GNU Affero General Public License, version 3,
- *    as published by the Free Software Foundation.
- *
- *    This program is distributed in the hope that it will be useful,
- *    but WITHOUT ANY WARRANTY; without even the implied warranty of
- *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- *    GNU Affero General Public License for more details.
- *
- *    You should have received a copy of the GNU Affero General Public License
- *    along with this program.  If not, see <http://www.gnu.org/licenses/>.
- *
- *    As a special exception, the copyright holders give permission to link the
- *    code of portions of this program with the OpenSSL library under certain
- *    conditions as described in each individual source file and distribute
- *    linked combinations including the program with the OpenSSL library. You
- *    must comply with the GNU Affero General Public License in all respects for
- *    all of the code used other than as permitted herein. If you modify file(s)
- *    with this exception, you may extend this exception to your version of the
- *    file(s), but you are not obligated to do so. If you do not wish to do so,
- *    delete this exception statement from your version. If you delete this
- *    exception statement from all source files in the program, then also delete
- *    it in the license file.
- */
-
-#include "mongo/platform/basic.h"
-
-#include "mongo/util/decoration_container.h"
-
-#include "mongo/util/decoration_registry.h"
-
-namespace mongo {
-
-DecorationContainer::DecorationContainer(const DecorationRegistry* registry, void* owner)
-    : _registry(registry),
-      _decorationData(new unsigned char[registry->getDecorationBufferSizeBytes()]) {
-    _registry->construct(this, owner);
-}
-
-DecorationContainer::~DecorationContainer() {
-    _registry->destruct(this);
-}
-
-}  // namespace mongo
diff --git a/src/mongo/util/decoration_container.h b/src/mongo/util/decoration_container.h
index e4fb89a4cff..647131bf09f 100644
--- a/src/mongo/util/decoration_container.h
+++ b/src/mongo/util/decoration_container.h
@@ -31,17 +31,21 @@
 #include <cstdint>
 #include <memory>
 
-#include "mongo/base/disallow_copying.h"
-
 namespace mongo {
 
+template <typename DecoratedType>
 class DecorationRegistry;
 
+template <typename DecoratedType>
+class Decorable;
+
 /**
  * An container for decorations.
  */
+template <typename DecoratedType>
 class DecorationContainer {
-    MONGO_DISALLOW_COPYING(DecorationContainer);
+    DecorationContainer(const DecorationContainer&) = delete;
+    DecorationContainer& operator=(const DecorationContainer&) = delete;
 
 public:
     /**
@@ -53,8 +57,9 @@ public:
         DecorationDescriptor() = default;
 
     private:
-        friend class DecorationContainer;
-        friend class DecorationRegistry;
+        friend DecorationContainer;
+        friend DecorationRegistry<DecoratedType>;
+        friend Decorable<DecoratedType>;
 
         explicit DecorationDescriptor(size_t index) : _index(index) {}
 
@@ -72,8 +77,9 @@ public:
         DecorationDescriptorWithType() = default;
 
     private:
-        friend class DecorationContainer;
-        friend class DecorationRegistry;
+        friend DecorationContainer;
+        friend DecorationRegistry<DecoratedType>;
+        friend Decorable<DecoratedType>;
 
         explicit DecorationDescriptorWithType(DecorationDescriptor raw) : _raw(std::move(raw)) {}
 
@@ -87,8 +93,24 @@ public:
      * have any declareDecoration() calls made on it while a DecorationContainer dependent on it
      * is in scope.
      */
-    explicit DecorationContainer(const DecorationRegistry* registry, void* owner);
-    ~DecorationContainer();
+    explicit DecorationContainer(Decorable<DecoratedType>* const decorated,
+                                 const DecorationRegistry<DecoratedType>* const registry)
+        : _registry(registry),
+          _decorationData(new unsigned char[registry->getDecorationBufferSizeBytes()]) {
+        // Because the decorations live in the externally allocated storage buffer at
+        // `_decorationData`, there needs to be a way to get back from a known location within this
+        // buffer to the type which owns those decorations.  We place a pointer to ourselves, a
+        // "back link" in the front of this storage buffer, as this is the easiest "well known
+        // location" to compute.
+        Decorable<DecoratedType>** const backLink =
+            reinterpret_cast<Decorable<DecoratedType>**>(_decorationData.get());
+        *backLink = decorated;
+        _registry->construct(this);
+    }
+
+    ~DecorationContainer() {
+        _registry->destroy(this);
+    }
 
     /**
      * Gets the decorated value for the given descriptor.
@@ -123,7 +145,7 @@ public:
     }
 
 private:
-    const DecorationRegistry* const _registry;
+    const DecorationRegistry<DecoratedType>* const _registry;
     const std::unique_ptr<unsigned char[]> _decorationData;
 };
 
diff --git a/src/mongo/util/decoration_registry.cpp b/src/mongo/util/decoration_registry.cpp
deleted file mode 100644
index 8ccc838bbe4..00000000000
--- a/src/mongo/util/decoration_registry.cpp
+++ /dev/null
@@ -1,90 +0,0 @@
-/**
- *    Copyright (C) 2015 MongoDB Inc.
- *
- *    This program is free software: you can redistribute it and/or  modify
- *    it under the terms of the GNU Affero General Public License, version 3,
- *    as published by the Free Software Foundation.
- *
- *    This program is distributed in the hope that it will be useful,
- *    but WITHOUT ANY WARRANTY; without even the implied warranty of
- *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- *    GNU Affero General Public License for more details.
- *
- *    You should have received a copy of the GNU Affero General Public License
- *    along with this program.  If not, see <http://www.gnu.org/licenses/>.
- *
- *    As a special exception, the copyright holders give permission to link the
- *    code of portions of this program with the OpenSSL library under certain
- *    conditions as described in each individual source file and distribute
- *    linked combinations including the program with the OpenSSL library. You
- *    must comply with the GNU Affero General Public License in all respects for
- *    all of the code used other than as permitted herein. If you modify file(s)
- *    with this exception, you may extend this exception to your version of the
- *    file(s), but you are not obligated to do so. If you do not wish to do so,
- *    delete this exception statement from your version. If you delete this
- *    exception statement from all source files in the program, then also delete
- *    it in the license file.
- */
-
-#include "mongo/platform/basic.h"
-
-#include "mongo/util/decoration_registry.h"
-
-namespace mongo {
-
-DecorationContainer::DecorationDescriptor DecorationRegistry::declareDecoration(
-    const size_t sizeBytes,
-    const size_t alignBytes,
-    const DecorationConstructorFn constructor,
-    const DecorationDestructorFn destructor) {
-    const size_t misalignment = _totalSizeBytes % alignBytes;
-    if (misalignment) {
-        _totalSizeBytes += alignBytes - misalignment;
-    }
-    DecorationContainer::DecorationDescriptor result(_totalSizeBytes);
-    _decorationInfo.push_back(DecorationInfo(result, constructor, destructor));
-    _totalSizeBytes += sizeBytes;
-    return result;
-}
-
-void DecorationRegistry::construct(DecorationContainer* container, void* owner) const {
-    auto iter = _decorationInfo.cbegin();
-    try {
-        for (; iter != _decorationInfo.cend(); ++iter) {
-            iter->constructor(container->getDecoration(iter->descriptor), owner);
-        }
-    } catch (...) {
-        try {
-            while (iter != _decorationInfo.cbegin()) {
-                --iter;
-                iter->destructor(container->getDecoration(iter->descriptor));
-            }
-        } catch (...) {
-            std::terminate();
-        }
-        throw;
-    }
-}
-
-void DecorationRegistry::destruct(DecorationContainer* container) const {
-    try {
-        for (DecorationInfoVector::const_reverse_iterator iter = _decorationInfo.rbegin(),
-                                                          end = _decorationInfo.rend();
-             iter != end;
-             ++iter) {
-            iter->destructor(container->getDecoration(iter->descriptor));
-        }
-    } catch (...) {
-        std::terminate();
-    }
-}
-
-DecorationRegistry::DecorationInfo::DecorationInfo(
-    DecorationContainer::DecorationDescriptor inDescriptor,
-    DecorationConstructorFn inConstructor,
-    DecorationDestructorFn inDestructor)
-    : descriptor(std::move(inDescriptor)),
-      constructor(std::move(inConstructor)),
-      destructor(std::move(inDestructor)) {}
-
-}  // namespace mongo
diff --git a/src/mongo/util/decoration_registry.h b/src/mongo/util/decoration_registry.h
index b6a3d879609..cbabc096d8a 100644
--- a/src/mongo/util/decoration_registry.h
+++ b/src/mongo/util/decoration_registry.h
@@ -28,6 +28,9 @@
 
 #pragma once
 
+#include <algorithm>
+#include <functional>
+#include <iterator>
 #include <type_traits>
 #include <vector>
 
@@ -35,6 +38,7 @@
 #include "mongo/base/static_assert.h"
 #include "mongo/stdx/functional.h"
 #include "mongo/util/decoration_container.h"
+#include "mongo/util/scopeguard.h"
 
 namespace mongo {
 
@@ -46,6 +50,7 @@ namespace mongo {
  * the decorations declared on r1, and a DecorationContainer constructed from r2 has instances
  * of the decorations declared on r2.
  */
+template <typename DecoratedType>
 class DecorationRegistry {
     MONGO_DISALLOW_COPYING(DecorationRegistry);
 
@@ -59,25 +64,15 @@ public:
      * NOTE: T's destructor must not throw exceptions.
      */
     template <typename T>
-    DecorationContainer::DecorationDescriptorWithType<T> declareDecoration() {
+    auto declareDecoration() {
         MONGO_STATIC_ASSERT_MSG(std::is_nothrow_destructible<T>::value,
                                 "Decorations must be nothrow destructible");
-        return DecorationContainer::DecorationDescriptorWithType<T>(std::move(declareDecoration(
-            sizeof(T), std::alignment_of<T>::value, &constructAt<T>, &destructAt<T>)));
+        return
+            typename DecorationContainer<DecoratedType>::template DecorationDescriptorWithType<T>(
+                std::move(declareDecoration(
+                    sizeof(T), std::alignment_of<T>::value, &constructAt<T>, &destroyAt<T>)));
     }
 
-    template <typename T, typename Owner>
-    DecorationContainer::DecorationDescriptorWithType<T> declareDecorationWithOwner() {
-        MONGO_STATIC_ASSERT_MSG(std::is_nothrow_destructible<T>::value,
-                                "Decorations must be nothrow destructible");
-        return DecorationContainer::DecorationDescriptorWithType<T>(
-            std::move(declareDecoration(sizeof(T),
-                                        std::alignment_of<T>::value,
-                                        &constructAtWithOwner<T, Owner>,
-                                        &destructAt<T>)));
-    }
-
-
     size_t getDecorationBufferSizeBytes() const {
         return _totalSizeBytes;
     }
@@ -88,33 +83,67 @@ public:
      *
      * Called by the DecorationContainer constructor. Do not call directly.
      */
-    void construct(DecorationContainer* decorable, void* owner) const;
+    void construct(DecorationContainer<DecoratedType>* const container) const {
+        using std::cbegin;
+
+        auto iter = cbegin(_decorationInfo);
+
+        auto cleanupFunction = [&iter, container, this ]() noexcept->void {
+            using std::crend;
+            std::for_each(std::make_reverse_iterator(iter),
+                          crend(this->_decorationInfo),
+                          [&](auto&& decoration) {
+                              decoration.destructor(
+                                  container->getDecoration(decoration.descriptor));
+                          });
+        };
+
+        auto cleanup = MakeGuard(std::move(cleanupFunction));
+
+        using std::cend;
+
+        for (; iter != cend(_decorationInfo); ++iter) {
+            iter->constructor(container->getDecoration(iter->descriptor));
+        }
+
+        cleanup.Dismiss();
+    }
 
     /**
      * Destroys the decorations declared in this registry on the given instance of "decorable".
      *
      * Called by the DecorationContainer destructor.  Do not call directly.
      */
-    void destruct(DecorationContainer* decorable) const;
+    void destroy(DecorationContainer<DecoratedType>* const container) const noexcept try {
+        for (auto& decoration : _decorationInfo) {
+            decoration.destructor(container->getDecoration(decoration.descriptor));
+        }
+    } catch (...) {
+        std::terminate();
+    }
 
 private:
     /**
      * Function that constructs (initializes) a single instance of a decoration.
      */
-    using DecorationConstructorFn = stdx::function<void(void*, void*)>;
+    using DecorationConstructorFn = void (*)(void*);
 
     /**
-     * Function that destructs (deinitializes) a single instance of a decoration.
+     * Function that destroys (deinitializes) a single instance of a decoration.
      */
-    using DecorationDestructorFn = stdx::function<void(void*)>;
+    using DecorationDestructorFn = void (*)(void*);
 
     struct DecorationInfo {
         DecorationInfo() {}
-        DecorationInfo(DecorationContainer::DecorationDescriptor descriptor,
-                       DecorationConstructorFn constructor,
-                       DecorationDestructorFn destructor);
-
-        DecorationContainer::DecorationDescriptor descriptor;
+        DecorationInfo(
+            typename DecorationContainer<DecoratedType>::DecorationDescriptor inDescriptor,
+            DecorationConstructorFn inConstructor,
+            DecorationDestructorFn inDestructor)
+            : descriptor(std::move(inDescriptor)),
+              constructor(std::move(inConstructor)),
+              destructor(std::move(inDestructor)) {}
+
+        typename DecorationContainer<DecoratedType>::DecorationDescriptor descriptor;
         DecorationConstructorFn constructor;
         DecorationDestructorFn destructor;
     };
@@ -122,17 +151,12 @@ private:
     using DecorationInfoVector = std::vector<DecorationInfo>;
 
     template <typename T>
-    static void constructAt(void* location, void* owner) {
+    static void constructAt(void* location) {
         new (location) T();
     }
 
-    template <typename T, typename Owner>
-    static void constructAtWithOwner(void* location, void* owner) {
-        new (location) T(static_cast<Owner*>(owner));
-    }
-
     template <typename T>
-    static void destructAt(void* location) {
+    static void destroyAt(void* location) {
         static_cast<T*>(location)->~T();
     }
 
@@ -142,13 +166,23 @@ private:
      *
      * NOTE: "destructor" must not throw exceptions.
      */
-    DecorationContainer::DecorationDescriptor declareDecoration(size_t sizeBytes,
-                                                                size_t alignBytes,
-                                                                DecorationConstructorFn constructor,
-                                                                DecorationDestructorFn destructor);
+    typename DecorationContainer<DecoratedType>::DecorationDescriptor declareDecoration(
+        const size_t sizeBytes,
+        const size_t alignBytes,
+        const DecorationConstructorFn constructor,
+        const DecorationDestructorFn destructor) {
+        const size_t misalignment = _totalSizeBytes % alignBytes;
+        if (misalignment) {
+            _totalSizeBytes += alignBytes - misalignment;
+        }
+        typename DecorationContainer<DecoratedType>::DecorationDescriptor result(_totalSizeBytes);
+        _decorationInfo.push_back(DecorationInfo(result, constructor, destructor));
+        _totalSizeBytes += sizeBytes;
+        return result;
+    }
 
     DecorationInfoVector _decorationInfo;
-    size_t _totalSizeBytes{0};
+    size_t _totalSizeBytes{sizeof(void*)};
 };
 
 }  // namespace mongo
diff --git a/src/mongo/util/net/SConscript b/src/mongo/util/net/SConscript
index 6d57e33310a..196f8af47a0 100644
--- a/src/mongo/util/net/SConscript
+++ b/src/mongo/util/net/SConscript
@@ -37,7 +37,6 @@ env.Library(
         '$BUILD_DIR/mongo/base',
         '$BUILD_DIR/mongo/db/auth/auth_rolename',
         '$BUILD_DIR/mongo/util/concurrency/ticketholder',
-        '$BUILD_DIR/mongo/util/decorable',
         'host',
     ],
     LIBDEPS_PRIVATE=[