1 files changed, 79 insertions, 0 deletions
diff --git a/src/libstd/sys/wasm/mutex.rs b/src/libstd/sys/wasm/mutex.rs
new file mode 100644
index 00000000000..4197bdcc808
--- /dev/null
+++ b/src/libstd/sys/wasm/mutex.rs
@@ -0,0 +1,79 @@
+// Copyright 2017 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+use cell::UnsafeCell;
+
+pub struct Mutex {
+    locked: UnsafeCell<bool>,
+}
+
+unsafe impl Send for Mutex {}
+unsafe impl Sync for Mutex {} // no threads on wasm
+
+impl Mutex {
+    pub const fn new() -> Mutex {
+        Mutex { locked: UnsafeCell::new(false) }
+    }
+
+    #[inline]
+    pub unsafe fn init(&mut self) {
+    }
+
+    #[inline]
+    pub unsafe fn lock(&self) {
+        let locked = self.locked.get();
+        assert!(!*locked, "cannot recursively acquire mutex");
+        *locked = true;
+    }
+
+    #[inline]
+    pub unsafe fn unlock(&self) {
+        *self.locked.get() = false;
+    }
+
+    #[inline]
+    pub unsafe fn try_lock(&self) -> bool {
+        let locked = self.locked.get();
+        if *locked {
+            false
+        } else {
+            *locked = true;
+            true
+        }
+    }
+
+    #[inline]
+    pub unsafe fn destroy(&self) {
+    }
+}
+
+// All empty stubs because wasm has no threads yet, so lock acquisition always
+// succeeds.
+pub struct ReentrantMutex {
+}
+
+impl ReentrantMutex {
+    pub unsafe fn uninitialized() -> ReentrantMutex {
+        ReentrantMutex { }
+    }
+
+    pub unsafe fn init(&mut self) {}
+
+    pub unsafe fn lock(&self) {}
+
+    #[inline]
+    pub unsafe fn try_lock(&self) -> bool {
+        true
+    }
+
+    pub unsafe fn unlock(&self) {}
+
+    pub unsafe fn destroy(&self) {}
+}