1 files changed, 51 insertions, 0 deletions
diff --git a/memory/gtest/TestJemalloc.cpp b/memory/gtest/TestJemalloc.cpp
new file mode 100644
index 000000000..f37c57376
--- /dev/null
+++ b/memory/gtest/TestJemalloc.cpp
@@ -0,0 +1,51 @@
+/* -*-  Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2; -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/mozalloc.h"
+#include "mozmemory.h"
+
+#include "gtest/gtest.h"
+
+static inline void
+TestOne(size_t size)
+{
+    size_t req = size;
+    size_t adv = malloc_good_size(req);
+    char* p = (char*)malloc(req);
+    size_t usable = moz_malloc_usable_size(p);
+    // NB: Using EXPECT here so that we still free the memory on failure.
+    EXPECT_EQ(adv, usable) <<
+           "malloc_good_size(" << req << ") --> " << adv << "; "
+           "malloc_usable_size(" << req << ") --> " << usable;
+    free(p);
+}
+
+static inline void
+TestThree(size_t size)
+{
+    ASSERT_NO_FATAL_FAILURE(TestOne(size - 1));
+    ASSERT_NO_FATAL_FAILURE(TestOne(size));
+    ASSERT_NO_FATAL_FAILURE(TestOne(size + 1));
+}
+
+TEST(Jemalloc, UsableSizeInAdvance)
+{
+  #define K   * 1024
+  #define M   * 1024 * 1024
+
+  /*
+   * Test every size up to a certain point, then (N-1, N, N+1) triplets for a
+   * various sizes beyond that.
+   */
+
+  for (size_t n = 0; n < 16 K; n++)
+    ASSERT_NO_FATAL_FAILURE(TestOne(n));
+
+  for (size_t n = 16 K; n < 1 M; n += 4 K)
+    ASSERT_NO_FATAL_FAILURE(TestThree(n));
+
+  for (size_t n = 1 M; n < 8 M; n += 128 K)
+    ASSERT_NO_FATAL_FAILURE(TestThree(n));
+}