1 files changed, 28 insertions, 0 deletions
diff --git a/staging_vespalib/src/vespa/vespalib/util/malloc_mmap_guard.h b/staging_vespalib/src/vespa/vespalib/util/malloc_mmap_guard.h
new file mode 100644
index 00000000000..03e6d38c03c
--- /dev/null
+++ b/staging_vespalib/src/vespa/vespalib/util/malloc_mmap_guard.h
@@ -0,0 +1,28 @@
+// Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+#pragma once
+
+#include <thread>
+
+namespace vespalib {
+
+/**
+ * Provides a hint to malloc implementation that all allocations in the scope of this guard
+ * will use mmap directly for allocation larger than the given limit.
+ * NB !! Note that guards can not be nested. Intention is to use around third party libraries where
+ * you do not control allocation yourself.
+ * The effect is implementation dependent. vespamalloc applies this only for the calling thread.
+ **/
+class MallocMmapGuard
+{
+public:
+    MallocMmapGuard(size_t mmapLimit);
+    MallocMmapGuard(const MallocMmapGuard &) = delete;
+    MallocMmapGuard & operator=(const MallocMmapGuard &) = delete;
+    MallocMmapGuard(MallocMmapGuard &&) = delete;
+    MallocMmapGuard & operator=(MallocMmapGuard &&) = delete;
+    ~MallocMmapGuard();
+private:
+    std::thread::id _threadId;
+};
+
+} // namespace vespalib