Change C++ standard to c++17 (#911)

* [skip ci]#668 - Update badge of README

* Fix README.md

* Fix README.md

* Merge remote-tracking branch 'upstream/master'

* #910 Change c++ standard to c++17

* Remove unused headers

CHANGELOG.md

@@ -19,6 +19,7 @@ Please mark all change in change log and use the issue from GitHub
 - \#771 - Add server build commit info interface
 - \#759 - Put C++ sdk out of milvus/core
 - \#815 - Support MinIO storage
+- \#910 - Change Milvus c++ standard to c++17
 
 ## Improvement
 - \#738 - Use Openblas / lapack from apt install

core/CMakeLists.txt

@@ -106,7 +106,7 @@ message(STATUS "Milvus version: "
         "${MILVUS_VERSION_MAJOR}.${MILVUS_VERSION_MINOR}.${MILVUS_VERSION_PATCH} "
         "(full: '${MILVUS_VERSION}')")
 
-set(CMAKE_CXX_STANDARD 14)
+set(CMAKE_CXX_STANDARD 17)
 set(CMAKE_CXX_STANDARD_REQUIRED on)
 
 if (CMAKE_SYSTEM_PROCESSOR MATCHES "(x86)|(X86)|(amd64)|(AMD64)")

core/src/index/CMakeLists.txt

@@ -25,7 +25,7 @@ message(STATUS "Building using CMake version: ${CMAKE_VERSION}")
 set(KNOWHERE_VERSION "0.6.0")
 string(REGEX MATCH "^[0-9]+\\.[0-9]+\\.[0-9]+" KNOWHERE_BASE_VERSION "${KNOWHERE_VERSION}")
 project(knowhere VERSION "${KNOWHERE_BASE_VERSION}" LANGUAGES C CXX)
-set(CMAKE_CXX_STANDARD 14)
+set(CMAKE_CXX_STANDARD 17)
 
 set(KNOWHERE_VERSION_MAJOR "${knowhere_VERSION_MAJOR}")
 set(KNOWHERE_VERSION_MINOR "${knowhere_VERSION_MINOR}")

core/src/main.cpp

@@ -16,17 +16,14 @@
 // under the License.
 
 #include <getopt.h>
-#include <libgen.h>
-#include <signal.h>
 #include <unistd.h>
+#include <csignal>
 #include <cstring>
 #include <string>
 
 #include "easyloggingpp/easylogging++.h"
-#include "metrics/Metrics.h"
 #include "server/Server.h"
 #include "src/version.h"
-#include "utils/CommonUtil.h"
 #include "utils/SignalUtil.h"
 
 INITIALIZE_EASYLOGGINGPP