From 15e71bd1a1a850ad80fbd631b80a3ede07f14b48 Mon Sep 17 00:00:00 2001
From: zhangyi <zhangyi@hangsheng.com.cn>
Date: Mon, 1 Jul 2019 17:28:02 +0800
Subject: [PATCH] add IPC_CONSTEXPR_; add variable_wrapper instead of
 fixed_alloc_policy

---
 build/ipc/ipc.pro                |  1 -
 src/ipc.cpp                      | 16 +++----
 src/memory/detail.h              | 72 --------------------------------
 src/memory/resource.h            |  5 +--
 src/memory/wrapper.h             | 68 +++++++++++++++++++++++++++---
 src/platform/detail.h            | 18 ++++----
 src/platform/tls_pointer_win.cpp | 20 +++++----
 test/test_mem.cpp                |  4 +-
 8 files changed, 94 insertions(+), 110 deletions(-)
 delete mode 100644 src/memory/detail.h

diff --git a/build/ipc/ipc.pro b/build/ipc/ipc.pro
index 233de62..534e272 100644
--- a/build/ipc/ipc.pro
+++ b/build/ipc/ipc.pro
@@ -22,7 +22,6 @@ HEADERS += \
     ../../include/tls_pointer.h \
     ../../include/pool_alloc.h \
     ../../include/buffer.h \
-    ../../src/memory/detail.h \
     ../../src/memory/alloc.h \
     ../../src/memory/wrapper.h \
     ../../src/memory/resource.h \
diff --git a/src/ipc.cpp b/src/ipc.cpp
index 00c27ce..3a8da8b 100644
--- a/src/ipc.cpp
+++ b/src/ipc.cpp
@@ -91,13 +91,15 @@ struct conn_info_head {
     shm::handle acc_h_;
 
     /*
-        <Remarks> thread_local may have some bugs.
-        See: https://sourceforge.net/p/mingw-w64/bugs/727/
-             https://sourceforge.net/p/mingw-w64/bugs/527/
-             https://github.com/Alexpux/MINGW-packages/issues/2519
-             https://github.com/ChaiScript/ChaiScript/issues/402
-             https://developercommunity.visualstudio.com/content/problem/124121/thread-local-variables-fail-to-be-initialized-when.html
-             https://software.intel.com/en-us/forums/intel-c-compiler/topic/684827
+     * <Remarks> thread_local may have some bugs.
+     *
+     * <Reference>
+     * - https://sourceforge.net/p/mingw-w64/bugs/727/
+     * - https://sourceforge.net/p/mingw-w64/bugs/527/
+     * - https://github.com/Alexpux/MINGW-packages/issues/2519
+     * - https://github.com/ChaiScript/ChaiScript/issues/402
+     * - https://developercommunity.visualstudio.com/content/problem/124121/thread-local-variables-fail-to-be-initialized-when.html
+     * - https://software.intel.com/en-us/forums/intel-c-compiler/topic/684827
     */
     tls::pointer<ipc::unordered_map<msg_id_t, cache_t>> recv_cache_;
 
diff --git a/src/memory/detail.h b/src/memory/detail.h
deleted file mode 100644
index a654f6b..0000000
--- a/src/memory/detail.h
+++ /dev/null
@@ -1,72 +0,0 @@
-#pragma once
-
-#include <cstddef>
-
-#include "memory/alloc.h"
-#include "platform/detail.h"
-
-namespace ipc {
-namespace mem {
-namespace detail {
-
-enum : std::size_t {
-    base_size = sizeof(void*)
-};
-
-#if __cplusplus >= 201703L
-constexpr std::size_t classify(std::size_t size) {
-    constexpr std::size_t mapping[] = {
-#else /*__cplusplus < 201703L*/
-inline std::size_t classify(std::size_t size) {
-    static const std::size_t mapping[] = {
-#endif/*__cplusplus < 201703L*/
-        /* 1 */
-        0 , 1 , 2 , 3 ,
-        /* 2 */
-        5 , 5 , 7 , 7 ,
-        9 , 9 , 11, 11,
-        13, 13, 15, 15,
-        /* 4 */
-        19, 19, 19, 19,
-        23, 23, 23, 23,
-        27, 27, 27, 27,
-        31, 31, 31, 31
-    };
-    size = (size - 1) / base_size;
-#if __cplusplus >= 201703L
-    return (size < std::size(mapping)) ? mapping[size] : 32;
-#else /*__cplusplus < 201703L*/
-    return (size < (sizeof(mapping) / sizeof(mapping[0]))) ? mapping[size] : 32;
-#endif/*__cplusplus < 201703L*/
-}
-
-template <template <std::size_t> class Fixed, typename F>
-decltype(auto) choose(std::size_t size, F&& f) {
-    return ipc::detail::static_switch<32>(classify(size), [&f](auto index) {
-        return f(Fixed<(decltype(index)::value + 1) * base_size>::instance());
-    }, [&f] {
-        return f(static_alloc{});
-    });
-}
-
-template <template <std::size_t> class Fixed>
-class fixed_alloc_policy {
-public:
-    static void clear() {
-        ipc::detail::static_for<32>([](auto index) {
-            Fixed<(decltype(index)::value + 1) * base_size>::instance().clear();
-        });
-    }
-
-    static void* alloc(std::size_t size) {
-        return choose<Fixed>(size, [size](auto&& fp) { return fp.alloc(size); });
-    }
-
-    static void free(void* p, std::size_t size) {
-        choose<Fixed>(size, [p](auto&& fp) { fp.free(p); });
-    }
-};
-
-} // namespace detail
-} // namespace mem
-} // namespace ipc
diff --git a/src/memory/resource.h b/src/memory/resource.h
index 627f968..97697a6 100644
--- a/src/memory/resource.h
+++ b/src/memory/resource.h
@@ -12,15 +12,14 @@
 
 #include "memory/alloc.h"
 #include "memory/wrapper.h"
-#include "memory/detail.h"
 #include "platform/detail.h"
 
 namespace ipc {
 namespace mem {
 
 template <std::size_t Size>
-using static_async_fixed = mem::static_wrapper<mem::async_wrapper<mem::fixed_alloc<Size>>>;
-using async_pool_alloc   = mem::detail::fixed_alloc_policy<static_async_fixed>;
+using static_async_fixed = static_wrapper<async_wrapper<fixed_alloc<Size>>>;
+using async_pool_alloc   = variable_wrapper<static_async_fixed>;
 
 template <typename T>
 using allocator = allocator_wrapper<T, async_pool_alloc>;
diff --git a/src/memory/wrapper.h b/src/memory/wrapper.h
index d8665ec..515a3f9 100644
--- a/src/memory/wrapper.h
+++ b/src/memory/wrapper.h
@@ -13,6 +13,8 @@
 #include "def.h"
 #include "rw_lock.h"
 #include "tls_pointer.h"
+
+#include "memory/alloc.h"
 #include "platform/detail.h"
 
 namespace ipc {
@@ -181,12 +183,8 @@ public:
         return get_alloc().alloc(size);
     }
 
-    void free(void* p) {
-        get_alloc().free(p);
-    }
-
-    void free(void* p, std::size_t /*size*/) {
-        free(p);
+    void free(void* p, std::size_t size) {
+        get_alloc().free(p, size);
     }
 };
 
@@ -217,5 +215,63 @@ public:
     }
 };
 
+////////////////////////////////////////////////////////////////
+/// Variable memory allocation wrapper
+////////////////////////////////////////////////////////////////
+
+template <std::size_t BaseSize = sizeof(void*)>
+struct default_mapping_policy {
+
+    enum : std::size_t {
+        base_size    = BaseSize,
+        classes_size = 32
+    };
+
+    static const std::size_t table[classes_size];
+
+    constexpr static std::size_t classify(std::size_t size) {
+        return (((size - 1) / base_size) < classes_size) ? table[((size - 1) / base_size)] : classes_size;
+    }
+};
+
+template <std::size_t B>
+const std::size_t default_mapping_policy<B>::table[default_mapping_policy<B>::classes_size] = {
+    /* 1 - 8 ~ 32 */
+    0 , 1 , 2 , 3 ,
+    /* 2 - 48 ~ 256 */
+    5 , 5 , 7 , 7 , 9 , 9 , 11, 11, 13, 13, 15, 15, 17, 17,
+    19, 19, 21, 21, 23, 23, 25, 25, 27, 27, 29, 29, 31, 31
+};
+
+template <template <std::size_t> class Fixed,
+          typename StaticAlloc = mem::static_alloc,
+          typename MappingP    = default_mapping_policy<>>
+class variable_wrapper {
+
+    template <typename F>
+    constexpr static auto choose(std::size_t size, F&& f) {
+        return ipc::detail::static_switch<MappingP::classes_size>(MappingP::classify(size), [&f](auto index) {
+            return f(Fixed<(decltype(index)::value + 1) * MappingP::base_size>{});
+        }, [&f] {
+            return f(StaticAlloc{});
+        });
+    }
+
+public:
+    static void clear() {
+        ipc::detail::static_for<MappingP::classes_size>([](auto index) {
+            Fixed<(decltype(index)::value + 1) * MappingP::base_size>::clear();
+        });
+    }
+
+    static void* alloc(std::size_t size) {
+        return choose(size, [size](auto&& alc) { return alc.alloc(size); });
+    }
+
+    static void free(void* p, std::size_t size) {
+        choose(size, [p, size](auto&& alc) { alc.free(p, size); });
+    }
+};
+
 } // namespace mem
 } // namespace ipc
diff --git a/src/platform/detail.h b/src/platform/detail.h
index 4daca2b..3b46345 100644
--- a/src/platform/detail.h
+++ b/src/platform/detail.h
@@ -24,12 +24,16 @@
 #ifdef IPC_STBIND_
 #   error "IPC_STBIND_ has been defined."
 #endif
+#ifdef IPC_CONSTEXPR_
+#   error "IPC_CONSTEXPR_ has been defined."
+#endif
 
 #if __cplusplus >= 201703L
 
 #define IPC_UNUSED_      [[maybe_unused]]
 #define IPC_FALLTHROUGH_ [[fallthrough]]
 #define IPC_STBIND_(A, B, ...) auto [A, B] = __VA_ARGS__
+#define IPC_CONSTEXPR_   constexpr
 
 #else /*__cplusplus < 201703L*/
 
@@ -48,6 +52,8 @@
     auto A     = std::get<0>(tp___); \
     auto B     = std::get<1>(tp___)
 
+#define IPC_CONSTEXPR_ inline
+
 #endif/*__cplusplus < 201703L*/
 
 #if __cplusplus >= 201703L
@@ -121,20 +127,12 @@ constexpr decltype(auto) static_switch(std::size_t i, F&& f, D&& def) {
 }
 
 template <typename F, std::size_t...I>
-#if __cplusplus >= 201703L
-constexpr void static_for(std::index_sequence<I...>, F&& f) {
-#else /*__cplusplus < 201703L*/
-inline void static_for(std::index_sequence<I...>, F&& f) {
-#endif/*__cplusplus < 201703L*/
+IPC_CONSTEXPR_ void static_for(std::index_sequence<I...>, F&& f) {
     IPC_UNUSED_ auto expand = { (std::forward<F>(f)(std::integral_constant<size_t, I>{}), 0)... };
 }
 
 template <std::size_t N, typename F>
-#if __cplusplus >= 201703L
-constexpr void static_for(F&& f) {
-#else /*__cplusplus < 201703L*/
-inline void static_for(F&& f) {
-#endif/*__cplusplus < 201703L*/
+IPC_CONSTEXPR_ void static_for(F&& f) {
     static_for(std::make_index_sequence<N>{}, std::forward<F>(f));
 }
 
diff --git a/src/platform/tls_pointer_win.cpp b/src/platform/tls_pointer_win.cpp
index f8b33fa..a66b331 100644
--- a/src/platform/tls_pointer_win.cpp
+++ b/src/platform/tls_pointer_win.cpp
@@ -6,15 +6,17 @@
 namespace ipc {
 
 /*
-    <Remarks>
-
-    Windows doesn't support a per-thread destructor with its TLS primitives.
-    So, here will build it manually by inserting a function to be called on each thread's exit.
-    See: https://www.codeproject.com/Articles/8113/Thread-Local-Storage-The-C-Way
-         https://src.chromium.org/viewvc/chrome/trunk/src/base/threading/thread_local_storage_win.cc
-         https://github.com/mirror/mingw-org-wsl/blob/master/src/libcrt/crt/tlssup.c
-         https://github.com/Alexpux/mingw-w64/blob/master/mingw-w64-crt/crt/tlssup.c
-         http://svn.boost.org/svn/boost/trunk/libs/thread/src/win32/tss_pe.cpp
+ * <Remarks>
+ *
+ * Windows doesn't support a per-thread destructor with its TLS primitives.
+ * So, here will build it manually by inserting a function to be called on each thread's exit.
+ *
+ * <Reference>
+ * - https://www.codeproject.com/Articles/8113/Thread-Local-Storage-The-C-Way
+ * - https://src.chromium.org/viewvc/chrome/trunk/src/base/threading/thread_local_storage_win.cc
+ * - https://github.com/mirror/mingw-org-wsl/blob/master/src/libcrt/crt/tlssup.c
+ * - https://github.com/Alexpux/mingw-w64/blob/master/mingw-w64-crt/crt/tlssup.c
+ * - http://svn.boost.org/svn/boost/trunk/libs/thread/src/win32/tss_pe.cpp
 */
 
 namespace {
diff --git a/test/test_mem.cpp b/test/test_mem.cpp
index 7bff870..44d060f 100644
--- a/test/test_mem.cpp
+++ b/test/test_mem.cpp
@@ -25,13 +25,13 @@ private slots:
     void test_alloc_free();
     void test_static();
     void test_pool();
-} /*unit__*/;
+} unit__;
 
 #include "test_mem.moc"
 
 constexpr int DataMin   = sizeof(void*);
 constexpr int DataMax   = sizeof(void*) * 16;
-constexpr int LoopCount = 10000000;
+constexpr int LoopCount = 1000000;
 
 std::vector<std::size_t> sizes__;