add codelab glog

runtime/.clang-format

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+# This file is used by clang-format to autoformat paddle source code
+#
+# The clang-format is part of llvm toolchain.
+# It need to install llvm and clang to format source code style.
+#
+# The basic usage is,
+#   clang-format -i -style=file PATH/TO/SOURCE/CODE
+#
+# The -style=file implicit use ".clang-format" file located in one of
+# parent directory.
+# The -i means inplace change.
+#
+# The document of clang-format is
+#   http://clang.llvm.org/docs/ClangFormat.html
+#   http://clang.llvm.org/docs/ClangFormatStyleOptions.html
+---
+Language:        Cpp
+BasedOnStyle:  Google
+IndentWidth:     4
+TabWidth:        4
+ContinuationIndentWidth: 4
+MaxEmptyLinesToKeep: 2
+AccessModifierOffset: -2  # The private/protected/public has no indent in class
+Standard:  Cpp11
+AllowAllParametersOfDeclarationOnNextLine: true
+BinPackParameters: false
+BinPackArguments: false
+...
+

runtime/engine/codelab/glog/CMakeLists.txt

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+cmake_minimum_required(VERSION 3.14 FATAL_ERROR)
+
+add_executable(glog_main ${CMAKE_CURRENT_SOURCE_DIR}/glog_main.cc)
+target_link_libraries(glog_main glog)
+
+
+add_executable(glog_logtostderr_main ${CMAKE_CURRENT_SOURCE_DIR}/glog_logtostderr_main.cc)
+target_link_libraries(glog_logtostderr_main glog)

runtime/engine/codelab/glog/README.md

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+# [GLOG](https://rpg.ifi.uzh.ch/docs/glog.html)
+
+Unless otherwise specified, glog writes to the filename `/tmp/<program name>.<hostname>.<user name>.log.<severity level>.<date>.<time>.<pid>` (e.g., "/tmp/hello_world.example.com.hamaji.log.INFO.20080709-222411.10474"). By default, glog copies the log messages of severity level ERROR or FATAL to standard error (stderr) in addition to log files.
+
+Several flags influence glog's output behavior. If the Google gflags library is installed on your machine, the configure script (see the INSTALL file in the package for detail of this script) will automatically detect and use it, allowing you to pass flags on the command line. For example, if you want to turn the flag --logtostderr on, you can start your application with the following command line:
+
+   `./your_application --logtostderr=1`
+
+If the Google gflags library isn't installed, you set flags via environment variables, prefixing the flag name with "GLOG_", e.g.
+
+   `GLOG_logtostderr=1 ./your_application`
+
+You can also modify flag values in your program by modifying global variables `FLAGS_*` . Most settings start working immediately after you update `FLAGS_*` . The exceptions are the flags related to destination files. For example, you might want to set `FLAGS_log_dir` before calling `google::InitGoogleLogging` . Here is an example:
+∂∂
+```c++
+   LOG(INFO) << "file";
+   // Most flags work immediately after updating values.
+   FLAGS_logtostderr = 1;
+   LOG(INFO) << "stderr";
+   FLAGS_logtostderr = 0;
+   // This won't change the log destination. If you want to set this
+   // value, you should do this before google::InitGoogleLogging .
+   FLAGS_log_dir = "/some/log/directory";
+   LOG(INFO) << "the same file";
+```
+
+* this is the test script:
+```
+# run 
+glog_test
+
+echo "------"
+export FLAGS_logtostderr=1 
+glog_test
+
+echo "------"
+glog_logtostderr_test
+```

runtime/engine/codelab/glog/glog_logtostderr_main.cc

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+// Copyright (c) 2022 PaddlePaddle Authors. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include <glog/logging.h>
+
+int main(int argc, char* argv[]) {
+    // Initialize Google’s logging library.
+    google::InitGoogleLogging(argv[0]);
+    google::InstallFailureSignalHandler();
+    FLAGS_logtostderr = 1;
+
+    LOG(INFO) << "Found " << 10 << " cookies";
+    LOG(ERROR) << "Found " << 10 << " error";
+}

runtime/engine/codelab/glog/glog_main.cc

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+// Copyright (c) 2022 PaddlePaddle Authors. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include <glog/logging.h>
+
+int main(int argc, char* argv[]) {
+    // Initialize Google’s logging library.
+    google::InitGoogleLogging(argv[0]);
+
+    LOG(INFO) << "Found " << 10 << " cookies";
+    LOG(ERROR) << "Found " << 10 << " error";
+}