common: add a class to safely wrap mlock/munlock

This class will allow mlocking small objects, of which there
may be several per page. It adds refcounting so pages are only
munlocked when the last object on that page munlocks.

1 files changed, 186 insertions, 0 deletions

diff --git a/tests/unit_tests/mlocker.cpp b/tests/unit_tests/mlocker.cpp
new file mode 100644
index 000000000..6e6048c6c
--- /dev/null
+++ b/tests/unit_tests/mlocker.cpp
@@ -0,0 +1,186 @@
+// Copyright (c) 2018, The Monero Project
+// 
+// All rights reserved.
+// 
+// Redistribution and use in source and binary forms, with or without modification, are
+// permitted provided that the following conditions are met:
+// 
+// 1. Redistributions of source code must retain the above copyright notice, this list of
+//    conditions and the following disclaimer.
+// 
+// 2. Redistributions in binary form must reproduce the above copyright notice, this list
+//    of conditions and the following disclaimer in the documentation and/or other
+//    materials provided with the distribution.
+// 
+// 3. Neither the name of the copyright holder nor the names of its contributors may be
+//    used to endorse or promote products derived from this software without specific
+//    prior written permission.
+// 
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
+// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
+// THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+// STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
+// THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#include "gtest/gtest.h"
+
+#include "misc_log_ex.h"
+#include "mlocker.h"
+
+#define BASE(data) (char*)(((uintptr_t)(data.get() + page_size - 1)) / page_size * page_size)
+
+TEST(mlocker, distinct_1)
+{
+  const size_t page_size = epee::mlocker::get_page_size();
+  ASSERT_TRUE(page_size > 0);
+  const size_t base_pages = epee::mlocker::get_num_locked_pages();
+  const size_t base_objects = epee::mlocker::get_num_locked_objects();
+  std::unique_ptr<char[]> data{new char[8 * page_size]};
+  epee::mlocker *m0 = new epee::mlocker(BASE(data), 1);
+  epee::mlocker *m1 = new epee::mlocker(BASE(data) + 2 * page_size, 1);
+  epee::mlocker *m2 = new epee::mlocker(BASE(data) + 3 * page_size, 1);
+  ASSERT_EQ(epee::mlocker::get_num_locked_pages(), base_pages + 3);
+  ASSERT_EQ(epee::mlocker::get_num_locked_objects(), base_objects + 3);
+  delete m0;
+  delete m1;
+  delete m2;
+  ASSERT_EQ(epee::mlocker::get_num_locked_pages(), base_pages + 0);
+  ASSERT_EQ(epee::mlocker::get_num_locked_objects(), base_objects + 0);
+}
+
+TEST(mlocker, distinct_full_page)
+{
+  const size_t page_size = epee::mlocker::get_page_size();
+  ASSERT_TRUE(page_size > 0);
+  const size_t base_pages = epee::mlocker::get_num_locked_pages();
+  const size_t base_objects = epee::mlocker::get_num_locked_objects();
+  std::unique_ptr<char[]> data{new char[8 * page_size]};
+  epee::mlocker *m0 = new epee::mlocker(BASE(data), page_size);
+  epee::mlocker *m1 = new epee::mlocker(BASE(data) + 2 * page_size, page_size);
+  epee::mlocker *m2 = new epee::mlocker(BASE(data) + 3 * page_size, page_size);
+  ASSERT_EQ(epee::mlocker::get_num_locked_pages(), base_pages + 3);
+  ASSERT_EQ(epee::mlocker::get_num_locked_objects(), base_objects + 3);
+  delete m0;
+  delete m1;
+  delete m2;
+  ASSERT_EQ(epee::mlocker::get_num_locked_pages(), base_pages + 0);
+  ASSERT_EQ(epee::mlocker::get_num_locked_objects(), base_objects + 0);
+}
+
+TEST(mlocker, identical)
+{
+  const size_t page_size = epee::mlocker::get_page_size();
+  ASSERT_TRUE(page_size >= 32);
+  const size_t base_pages = epee::mlocker::get_num_locked_pages();
+  const size_t base_objects = epee::mlocker::get_num_locked_objects();
+  std::unique_ptr<char[]> data{new char[8 * page_size]};
+  epee::mlocker *m0 = new epee::mlocker(BASE(data) + page_size, 32);
+  epee::mlocker *m1 = new epee::mlocker(BASE(data) + page_size, 32);
+  epee::mlocker *m2 = new epee::mlocker(BASE(data) + page_size, 32);
+  ASSERT_EQ(epee::mlocker::get_num_locked_pages(), base_pages + 1);
+  ASSERT_EQ(epee::mlocker::get_num_locked_objects(), base_objects + 3);
+  delete m1;
+  ASSERT_EQ(epee::mlocker::get_num_locked_pages(), base_pages + 1);
+  ASSERT_EQ(epee::mlocker::get_num_locked_objects(), base_objects + 2);
+  delete m0;
+  delete m2;
+  ASSERT_EQ(epee::mlocker::get_num_locked_pages(), base_pages + 0);
+  ASSERT_EQ(epee::mlocker::get_num_locked_objects(), base_objects + 0);
+}
+
+TEST(mlocker, overlapping_small)
+{
+  const size_t page_size = epee::mlocker::get_page_size();
+  ASSERT_TRUE(page_size >= 64);
+  const size_t base_pages = epee::mlocker::get_num_locked_pages();
+  const size_t base_objects = epee::mlocker::get_num_locked_objects();
+  std::unique_ptr<char[]> data{new char[8 * page_size]};
+  epee::mlocker *m0 = new epee::mlocker(BASE(data), 32);
+  epee::mlocker *m1 = new epee::mlocker(BASE(data) + 16, 32);
+  epee::mlocker *m2 = new epee::mlocker(BASE(data) + 8, 32);
+  ASSERT_EQ(epee::mlocker::get_num_locked_pages(), base_pages + 1);
+  ASSERT_EQ(epee::mlocker::get_num_locked_objects(), base_objects + 3);
+  delete m1;
+  ASSERT_EQ(epee::mlocker::get_num_locked_pages(), base_pages + 1);
+  ASSERT_EQ(epee::mlocker::get_num_locked_objects(), base_objects + 2);
+  delete m2;
+  delete m0;
+  ASSERT_EQ(epee::mlocker::get_num_locked_pages(), base_pages + 0);
+  ASSERT_EQ(epee::mlocker::get_num_locked_objects(), base_objects + 0);
+}
+
+TEST(mlocker, multi_page)
+{
+  const size_t page_size = epee::mlocker::get_page_size();
+  ASSERT_TRUE(page_size > 0);
+  const size_t base_pages = epee::mlocker::get_num_locked_pages();
+  const size_t base_objects = epee::mlocker::get_num_locked_objects();
+  std::unique_ptr<char[]> data{new char[8 * page_size]};
+  epee::mlocker *m0 = new epee::mlocker(BASE(data) + page_size, page_size * 3);
+  ASSERT_EQ(epee::mlocker::get_num_locked_pages(), base_pages + 3);
+  ASSERT_EQ(epee::mlocker::get_num_locked_objects(), base_objects + 1);
+  epee::mlocker *m1 = new epee::mlocker(BASE(data) + page_size * 7, page_size);
+  ASSERT_EQ(epee::mlocker::get_num_locked_pages(), base_pages + 4);
+  ASSERT_EQ(epee::mlocker::get_num_locked_objects(), base_objects + 2);
+  delete m0;
+  ASSERT_EQ(epee::mlocker::get_num_locked_pages(), base_pages + 1);
+  ASSERT_EQ(epee::mlocker::get_num_locked_objects(), base_objects + 1);
+  delete m1;
+  ASSERT_EQ(epee::mlocker::get_num_locked_pages(), base_pages + 0);
+  ASSERT_EQ(epee::mlocker::get_num_locked_objects(), base_objects + 0);
+}
+
+TEST(mlocker, cross_page)
+{
+  const size_t page_size = epee::mlocker::get_page_size();
+  ASSERT_TRUE(page_size > 32);
+  const size_t base_pages = epee::mlocker::get_num_locked_pages();
+  const size_t base_objects = epee::mlocker::get_num_locked_objects();
+  std::unique_ptr<char[]> data{new char[2 * page_size]};
+  epee::mlocker *m0 = new epee::mlocker(BASE(data) + page_size - 1, 2);
+  ASSERT_EQ(epee::mlocker::get_num_locked_pages(), base_pages + 2);
+  ASSERT_EQ(epee::mlocker::get_num_locked_objects(), base_objects + 1);
+  delete m0;
+  ASSERT_EQ(epee::mlocker::get_num_locked_pages(), base_pages + 0);
+  ASSERT_EQ(epee::mlocker::get_num_locked_objects(), base_objects + 0);
+}
+
+TEST(mlocker, redundant)
+{
+  const size_t page_size = epee::mlocker::get_page_size();
+  const size_t base_pages = epee::mlocker::get_num_locked_pages();
+  const size_t base_objects = epee::mlocker::get_num_locked_objects();
+  std::unique_ptr<char[]> data{new char[2 * page_size]};
+  ASSERT_EQ(epee::mlocker::get_num_locked_pages(), base_pages + 0);
+  ASSERT_EQ(epee::mlocker::get_num_locked_objects(), base_objects + 0);
+  epee::mlocker *m0 = new epee::mlocker(BASE(data), 32);
+  ASSERT_EQ(epee::mlocker::get_num_locked_pages(), base_pages + 1);
+  ASSERT_EQ(epee::mlocker::get_num_locked_objects(), base_objects + 1);
+  epee::mlocker *m1 = new epee::mlocker(BASE(data), 32);
+  ASSERT_EQ(epee::mlocker::get_num_locked_pages(), base_pages + 1);
+  ASSERT_EQ(epee::mlocker::get_num_locked_objects(), base_objects + 2);
+  delete m1;
+  ASSERT_EQ(epee::mlocker::get_num_locked_pages(), base_pages + 1);
+  ASSERT_EQ(epee::mlocker::get_num_locked_objects(), base_objects + 1);
+  delete m0;
+  ASSERT_EQ(epee::mlocker::get_num_locked_pages(), base_pages + 0);
+  ASSERT_EQ(epee::mlocker::get_num_locked_objects(), base_objects + 0);
+}
+
+TEST(mlocker, mlocked)
+{
+  const size_t base_pages = epee::mlocker::get_num_locked_pages();
+  const size_t base_objects = epee::mlocker::get_num_locked_objects();
+  {
+    struct Foo { uint64_t u; };
+    epee::mlocked<Foo> l;
+    ASSERT_EQ(epee::mlocker::get_num_locked_pages(), base_pages + 1);
+    ASSERT_EQ(epee::mlocker::get_num_locked_objects(), base_objects + 1);
+  }
+  ASSERT_EQ(epee::mlocker::get_num_locked_pages(), base_pages + 0);
+  ASSERT_EQ(epee::mlocker::get_num_locked_objects(), base_objects + 0);
+}