From daaa881cfe3466c298fa44812b8477a23d25b756 Mon Sep 17 00:00:00 2001
From: Sergey Vojtovich <svoj@mariadb.org>
Date: Tue, 4 Feb 2020 22:30:08 +0400
Subject: [PATCH] libpmem cmake macros

Also added support for MAP_SYNC. It allows to achieve decent performance
with DAX devices even when libpmem is unavailable.

Fixed Windows version of my_msync(): according to manual FlushViewOfFile()
may return before flush is actually completed. It is advised to issue
FlushFileBuffers() after FlushViewOfFile().
---
 CMakeLists.txt   |  1 +
 cmake/pmem.cmake | 13 +++++++++++++
 include/my_sys.h |  7 +++++++
 mysys/my_mmap.c  | 19 ++++++++++++++++++-
 4 files changed, 39 insertions(+), 1 deletion(-)
 create mode 100644 cmake/pmem.cmake

diff --git a/CMakeLists.txt b/CMakeLists.txt
index ce5b45aaae1..cf8b42d0430 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -168,6 +168,7 @@ INCLUDE(mysql_add_executable)
 INCLUDE(symlinks)
 INCLUDE(compile_flags)
 INCLUDE(crc32)
+INCLUDE(pmem)
 
 # Handle options
 OPTION(DISABLE_SHARED 
diff --git a/cmake/pmem.cmake b/cmake/pmem.cmake
new file mode 100644
index 00000000000..b59db3cc1f9
--- /dev/null
+++ b/cmake/pmem.cmake
@@ -0,0 +1,13 @@
+INCLUDE(CheckIncludeFiles)
+OPTION(WITH_PMEM "Enable persistent memory features" OFF)
+IF(WITH_PMEM)
+  FIND_LIBRARY(LIBPMEM pmem)
+  CHECK_INCLUDE_FILES(libpmem.h HAVE_LIBPMEM_H)
+  IF (NOT LIBPMEM)
+    MESSAGE(FATAL_ERROR "Can't find libpmem")
+  ELSEIF(NOT HAVE_LIBPMEM_H)
+    MESSAGE(FATAL_ERROR "Can't find libpmem.h")
+  ELSE()
+    ADD_DEFINITIONS(-DHAVE_PMEM)
+  ENDIF()
+ENDIF()
diff --git a/include/my_sys.h b/include/my_sys.h
index f20bbc700b3..c2ba72b4d66 100644
--- a/include/my_sys.h
+++ b/include/my_sys.h
@@ -964,6 +964,13 @@ extern ulonglong my_getcputime(void);
 #define available_stack_size(CUR,END) (long) ((char*)(END) - (char*)(CUR))
 #endif
 
+#ifndef MAP_SYNC
+#define MAP_SYNC 0x80000
+#endif
+#ifndef MAP_SHARED_VALIDATE
+#define MAP_SHARED_VALIDATE 0x03
+#endif
+
 #ifdef HAVE_SYS_MMAN_H
 #ifndef MAP_NOSYNC
 #define MAP_NOSYNC      0
diff --git a/mysys/my_mmap.c b/mysys/my_mmap.c
index 9d84c1c76f6..e04f4addd3d 100644
--- a/mysys/my_mmap.c
+++ b/mysys/my_mmap.c
@@ -29,6 +29,10 @@ int my_msync(int fd, void *addr, size_t len, int flags)
 
 #elif defined(_WIN32)
 
+#ifndef FILE_DAX_VOLUME
+#define FILE_DAX_VOLUME 0x20000000
+#endif
+
 static SECURITY_ATTRIBUTES mmap_security_attributes=
   {sizeof(SECURITY_ATTRIBUTES), 0, TRUE};
 
@@ -61,6 +65,18 @@ void *my_mmap(void *addr, size_t len, int prot,
    */
   CloseHandle(hFileMap);
 
+  if (flags & MAP_SYNC)
+  {
+    DWORD filesystemFlags;
+    if (!GetVolumeInformationByHandleW(hFile, NULL, 0, NULL, NULL,
+                                       &filesystemFlags, NULL, 0) ||
+        !(filesystemFlags & FILE_DAX_VOLUME))
+    {
+      UnmapViewOfFile(ptr);
+      ptr= NULL;
+    }
+  }
+
   if (ptr)
   {
     DBUG_PRINT("mysys", ("mapped addr: %p", ptr));
@@ -79,7 +95,8 @@ int my_munmap(void *addr, size_t len)
 
 int my_msync(int fd, void *addr, size_t len, int flags)
 {
-  return FlushViewOfFile(addr, len) ? 0 : -1;
+  return FlushViewOfFile(addr, len) &&
+         FlushFileBuffers(my_get_osfhandle(fd)) ? 0 : -1;
 }
 
 #else