ircd::allocator: Add trim() if available.

include/ircd/allocator.h

@@ -24,6 +24,8 @@ namespace ircd::allocator
 	template<class T = char> struct dynamic;
 	template<class T = char, size_t = 512> struct fixed;
 	template<class T> struct node;
+
+	bool trim(const size_t &pad = 0); // malloc_trim(3)
 };
 
 /// Profiling counters.

ircd/allocator.cc

@@ -8,6 +8,8 @@
 // copyright notice and this permission notice is present in all copies. The
 // full license for this software is available in the LICENSE file.
 
+#include <RB_INC_MALLOC_H
+
 // Uncomment or -D this #define to enable our own crude but simple ability to
 // profile dynamic memory usage. Global `new` and `delete` will be captured
 // here by this definition file into thread_local counters accessible via
@@ -16,6 +18,20 @@
 //
 // #define RB_PROF_ALLOC
 
+#if defined(__GNU_LIBRARY__) && defined(HAVE_MALLOC_H)
+bool
+ircd::allocator::trim(const size_t &pad)
+{
+	return malloc_trim(pad);
+}
+#else
+bool
+ircd::allocator::trim(const size_t &pad)
+{
+	return false;
+}
+#endif
+
 //
 // allocator::state
 //