tests: add (another) allocator test

Test that realloc() shrinking a block doesn't do an extra allocation.

configure.py

@@ -133,6 +133,7 @@ def debug_flag(compiler):
     'tests/timertest',
     'tests/tcp_test',
     'tests/futures_test',
+    'tests/alloc_test',
     'tests/foreign_ptr_test',
     'tests/smp_test',
     'tests/thread_test',
@@ -295,6 +296,7 @@ def have_xen():
     'tests/tcp_test': ['tests/tcp_test.cc'] + core + libnet,
     'tests/timertest': ['tests/timertest.cc'] + core,
     'tests/futures_test': ['tests/futures_test.cc'] + core + boost_test_lib,
+    'tests/alloc_test': ['tests/alloc_test.cc'] + core + boost_test_lib,
     'tests/foreign_ptr_test': ['tests/foreign_ptr_test.cc'] + core + boost_test_lib,
     'tests/semaphore_test': ['tests/semaphore_test.cc'] + core + boost_test_lib,
     'tests/smp_test': ['tests/smp_test.cc'] + core,

test.py

@@ -24,6 +24,7 @@
 import re
 
 boost_tests = [
+    'alloc_test',
     'futures_test',
     'thread_test',
     'memcached/test_ascii_parser',

tests/alloc_test.cc

@@ -0,0 +1,37 @@
+/*
+ * This file is open source software, licensed to you under the terms
+ * of the Apache License, Version 2.0 (the "License").  See the NOTICE file
+ * distributed with this work for additional information regarding copyright
+ * ownership.  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.
+ */
+/*
+ * Copyright (C) 2015 Cloudius Systems, Ltd.
+ */
+
+#include "tests/test-utils.hh"
+#include "core/memory.hh"
+
+
+SEASTAR_TEST_CASE(alloc_almost_all_and_realloc_it_with_a_smaller_size) {
+#ifndef DEFAULT_ALLOCATOR
+    auto all = memory::stats().total_memory();
+    auto obj = malloc(all - (10 << 20));
+    BOOST_REQUIRE(obj != nullptr);
+    auto obj2 = realloc(obj, all - (11 << 20));
+    BOOST_REQUIRE(obj == obj2);
+    free(obj2);
+#endif
+    return make_ready_future<>();
+}
+