Globablly limit alloc to 1.75GB

diff --git a/src/main.rs b/src/main.rs
index c496f14110d9648da2deafcafebf77ab2cd23f75..316ca12b3b29b1405b3b863abc713838275e4cb3 100644 (file)
--- a/src/main.rs
+++ b/src/main.rs
@@ -40,6 +40,48 @@ static mut TOR_PROXY: Option<SocketAddr> = None;
 pub static START_SHUTDOWN: AtomicBool = AtomicBool::new(false);
 static SCANNING: AtomicBool = AtomicBool::new(false);
 
+
+use std::alloc::{GlobalAlloc, Layout, System};
+use std::ptr;
+use std::sync::atomic::AtomicUsize;
+
+// We keep track of all memory allocated by Rust code, refusing new allocations if it exceeds
+// 1.75GB.
+//
+// Note that while Rust's std, in general, should panic in response to a null allocation, it
+// is totally conceivable that some code will instead dereference this null pointer, which
+// would violate our guarantees that Rust modules should never crash the entire application.
+//
+// In the future, as upstream Rust explores a safer allocation API (eg the Alloc API which
+// returns Results instead of raw pointers, or redefining the GlobalAlloc API to allow
+// panic!()s inside of alloc calls), we should switch to those, however these APIs are
+// currently unstable.
+const TOTAL_MEM_LIMIT_BYTES: usize = (1024 + 756) * 1024 * 1024;
+static TOTAL_MEM_ALLOCD: AtomicUsize = AtomicUsize::new(0);
+struct MemoryLimitingAllocator;
+unsafe impl GlobalAlloc for MemoryLimitingAllocator {
+       unsafe fn alloc(&self, layout: Layout) -> *mut u8 {
+               let len = layout.size();
+               if len > TOTAL_MEM_LIMIT_BYTES {
+                       return ptr::null_mut();
+               }
+               if TOTAL_MEM_ALLOCD.fetch_add(len, Ordering::AcqRel) + len > TOTAL_MEM_LIMIT_BYTES {
+                       TOTAL_MEM_ALLOCD.fetch_sub(len, Ordering::AcqRel);
+                       return ptr::null_mut();
+               }
+               System.alloc(layout)
+       }
+
+       unsafe fn dealloc(&self, ptr: *mut u8, layout: Layout) {
+               System.dealloc(ptr, layout);
+               TOTAL_MEM_ALLOCD.fetch_sub(layout.size(), Ordering::AcqRel);
+       }
+}
+
+#[global_allocator]
+static ALLOC: MemoryLimitingAllocator = MemoryLimitingAllocator;
+
+
 struct PeerState {
        request: Arc<(u64, BlockHash, Block)>,
        node_services: u64,