Merge pull request #1032 from karczex/pool_example

Add example for using pool as a class member

Author: igchor

examples/CMakeLists.txt

@@ -224,6 +224,8 @@ add_example(concurrent_hash_map_string concurrent_hash_map/concurrent_hash_map_s
 
 add_example(pool pool/pool.cpp)
 
+add_example(pool_as_class_member pool/pool_as_class_member.cpp)
+
 add_example(mutex mutex/mutex.cpp)
 
 add_example(make_persistent make_persistent/make_persistent.cpp)

examples/pool/CMakeLists.txt

@@ -1,5 +1,5 @@
 # SPDX-License-Identifier: BSD-3-Clause
-# Copyright 2020, Intel Corporation
+# Copyright 2020-2021, Intel Corporation
 
 cmake_minimum_required(VERSION 3.4)
 project(pool CXX)
@@ -21,6 +21,10 @@ endif()
 
 link_directories(${LIBPMEMOBJ++_LIBRARY_DIRS})
 
+add_executable(pool_as_class_member pool_as_class_member.cpp)
+target_include_directories(pool_as_class_member PUBLIC ${LIBPMEMOBJ++_INCLUDE_DIRS} . ..)
+target_link_libraries(pool_as_class_member ${LIBPMEMOBJ++_LIBRARIES} ${CMAKE_THREAD_LIBS_INIT})
+
 add_executable(pool pool.cpp)
 target_include_directories(pool PUBLIC ${LIBPMEMOBJ++_INCLUDE_DIRS} . ..)
 target_link_libraries(pool ${LIBPMEMOBJ++_LIBRARIES} ${CMAKE_THREAD_LIBS_INIT})

examples/pool/pool_as_class_member.cpp

@@ -0,0 +1,96 @@
+// SPDX-License-Identifier: BSD-3-Clause
+/* Copyright 2021, Intel Corporation */
+
+/*
+ * pool_as_class_member.cpp -- Example shows how to manage pool using RAII
+ * idiom.
+ */
+
+#include <iostream>
+//! [pool_class_member_example]
+#include <libpmemobj++/p.hpp>
+#include <libpmemobj++/persistent_ptr.hpp>
+#include <libpmemobj++/pool.hpp>
+
+using namespace pmem::obj;
+
+class Foo {
+private:
+	/* pool root structure */
+	struct persistent_data {
+		p<int> some_variable;
+	};
+
+	using pool_type = pmem::obj::pool<persistent_data>;
+	/* pool object */
+	pool_type pop;
+
+	const char *layout = "pool_layout";
+
+public:
+	Foo(const char *poolfile_path)
+	{
+		/* Create a pmemobj pool. */
+		if (pool_type::check(poolfile_path, layout) == 1) {
+			pop = pool_type::open(poolfile_path, layout);
+		} else {
+			std::cerr << "Cannot open pool" << std::endl
+				  << "Trying to create a new one " << std::endl;
+			pop = pool_type::create("poolfile", layout,
+						PMEMOBJ_MIN_POOL);
+		}
+	}
+
+	Foo() = delete;
+
+	~Foo()
+	{
+		/* Close a pmemobj pool */
+		pop.close();
+	}
+
+	void
+	set(int variable)
+	{
+		auto root_obj = pop.root();
+		root_obj->some_variable = variable;
+		pop.persist(root_obj->some_variable);
+	}
+
+	void
+	increment()
+	{
+		set(pop.root()->some_variable + 1);
+	}
+
+	void
+	print()
+	{
+		std::cout << pop.root()->some_variable << std::endl;
+	}
+};
+
+void
+pool_example()
+{
+	auto foo = Foo("poolfile");
+	foo.print();
+	foo.set(42);
+	foo.print();
+	foo.increment();
+	foo.print();
+}
+//! [pool_class_member_example]
+
+int
+main()
+{
+	try {
+		pool_example();
+	} catch (const std::exception &e) {
+		std::cerr << "Exception " << e.what() << std::endl;
+		return -1;
+	}
+
+	return 0;
+}

include/libpmemobj++/pool.hpp

@@ -43,6 +43,9 @@ class persistent_ptr;
  * where providing pool template argument is undesirable. The typical usage
  * example would be:
  * @snippet pool/pool.cpp pool_base_example
+ *
+ * The exmple of using pool with RAII idiom:
+ * @snippet pool/pool_as_class_member.cpp  pool_class_member_example
  */
 class pool_base {
 public: