Add memshred feature to stress2

Author: spacejam

benchmarks/stress2/Cargo.toml

@@ -24,6 +24,7 @@ measure_allocs = ["sled/measure_allocs"]
 jemalloc = ["jemallocator"]
 logging = ["env_logger", "log", "color-backtrace"]
 dh = ["dhat"]
+memshred = []
 
 [dependencies]
 rand = "0.7.3"

benchmarks/stress2/src/main.rs

@@ -6,18 +6,47 @@ use std::{
     thread,
 };
 
-#[cfg(feature = "jemalloc")]
-use jemallocator::Jemalloc;
-
 #[cfg(feature = "dh")]
 use dhat::{Dhat, DhatAlloc};
 
 use num_format::{Locale, ToFormattedString};
 use rand::{thread_rng, Rng};
 
-#[global_allocator]
 #[cfg(feature = "jemalloc")]
-static ALLOCATOR: Jemalloc = Jemalloc;
+mod alloc {
+    use std::alloc::Layout;
+    use jemallocator::Jemalloc;
+
+    #[global_allocator]
+    static ALLOCATOR: Jemalloc = Jemalloc;
+}
+
+#[cfg(feature = "memshred")]
+mod alloc {
+    use std::alloc::{System, Layout};
+
+    #[global_allocator]
+    static ALLOCATOR: Alloc = Alloc;
+
+    #[derive(Default, Debug, Clone, Copy)]
+    struct Alloc;
+
+    unsafe impl std::alloc::GlobalAlloc for Alloc {
+        unsafe fn alloc(&self, layout: Layout) -> *mut u8 {
+            let ret = System.alloc(layout);
+            assert_ne!(ret, std::ptr::null_mut());
+            std::ptr::write_bytes(ret, 0xa1, layout.size());
+            ret
+        }
+
+        unsafe fn dealloc(&self, ptr: *mut u8, layout: Layout) {
+            std::ptr::write_bytes(ptr, 0xde, layout.size());
+            System.dealloc(ptr, layout)
+
+        }
+    }
+}
+
 
 #[global_allocator]
 #[cfg(feature = "dh")]