SERVER-59139 refactor to use abseil for int128

3 files changed, 63 insertions, 3 deletions

diff --git a/src/mongo/platform/SConscript b/src/mongo/platform/SConscript
index 68ab49dad4c..71a0a57772d 100644
--- a/src/mongo/platform/SConscript
+++ b/src/mongo/platform/SConscript
@@ -13,6 +13,7 @@ env.CppUnitTest(
         'atomic_word_test.cpp',
         'bits_test.cpp',
         'endian_test.cpp',
+        'int128_test.cpp',
         'mutex_test.cpp',
         'process_id_test.cpp',
         'random_test.cpp',
diff --git a/src/mongo/platform/int128.h b/src/mongo/platform/int128.h
index 67c3b27232a..093c33cfe6d 100644
--- a/src/mongo/platform/int128.h
+++ b/src/mongo/platform/int128.h
@@ -29,7 +29,7 @@
 
 #pragma once
 
-#include <boost/multiprecision/cpp_int.hpp>
+#include <absl/numeric/int128.h>
 
-using uint128_t = boost::multiprecision::uint128_t;
-using int128_t = boost::multiprecision::int128_t;
+using uint128_t = absl::uint128;
+using int128_t = absl::int128;
diff --git a/src/mongo/platform/int128_test.cpp b/src/mongo/platform/int128_test.cpp
new file mode 100644
index 00000000000..be36cd3c4ed
--- /dev/null
+++ b/src/mongo/platform/int128_test.cpp
@@ -0,0 +1,59 @@
+/**
+ *    Copyright (C) 2021-present MongoDB, Inc.
+ *
+ *    This program is free software: you can redistribute it and/or modify
+ *    it under the terms of the Server Side Public License, version 1,
+ *    as published by MongoDB, Inc.
+ *
+ *    This program is distributed in the hope that it will be useful,
+ *    but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *    Server Side Public License for more details.
+ *
+ *    You should have received a copy of the Server Side Public License
+ *    along with this program. If not, see
+ *    <http://www.mongodb.com/licensing/server-side-public-license>.
+ *
+ *    As a special exception, the copyright holders give permission to link the
+ *    code of portions of this program with the OpenSSL library under certain
+ *    conditions as described in each individual source file and distribute
+ *    linked combinations including the program with the OpenSSL library. You
+ *    must comply with the Server Side Public License in all respects for
+ *    all of the code used other than as permitted herein. If you modify file(s)
+ *    with this exception, you may extend this exception to your version of the
+ *    file(s), but you are not obligated to do so. If you do not wish to do so,
+ *    delete this exception statement from your version. If you delete this
+ *    exception statement from all source files in the program, then also delete
+ *    it in the license file.
+ */
+
+#include "mongo/platform/int128.h"
+#include "mongo/unittest/unittest.h"
+
+using namespace mongo;
+
+// Asserts that we can cast to uint128_t and cast back as well that the expected high and low bits
+// after cast are following 2's complement.
+void assertCastIsValid(int128_t val, uint64_t expectedHi, uint64_t expectedLo) {
+    uint128_t castedInt = static_cast<uint128_t>(val);
+    ASSERT_EQUALS(absl::Uint128High64(castedInt), expectedHi);
+    ASSERT_EQUALS(absl::Uint128Low64(castedInt), expectedLo);
+    int128_t backToSigned = static_cast<int128_t>(castedInt);
+    ASSERT_EQUALS(val, backToSigned);
+}
+
+TEST(Int128, TestCastingPositive) {
+    assertCastIsValid(12345, 0, 12345);
+}
+
+TEST(Int128, TestCastingNegative) {
+    assertCastIsValid(-12345, 0xFFFFFFFFFFFFFFFF, 0xFFFFFFFFFFFFCFC7);
+}
+
+TEST(Int128, MaxPositiveInt) {
+    assertCastIsValid(std::numeric_limits<int128_t>::max(), 0x7FFFFFFFFFFFFFFF, 0xFFFFFFFFFFFFFFFF);
+}
+
+TEST(Int128, MaxNegativeInt) {
+    assertCastIsValid(std::numeric_limits<int128_t>::min(), 0x8000000000000000, 0);
+}