Merge pull request #123 from faern/add-sgx-thread-parker

Add SGX thread parker

.travis.yml

@@ -11,6 +11,9 @@ before_script:
 - |
   pip install 'travis-cargo<0.2' --user &&
   export PATH=$HOME/.local/bin:$PATH
+- if [ "${TRAVIS_RUST_VERSION}" = "nightly" ]; then
+    rustup target add x86_64-fortanix-unknown-sgx;
+  fi
 
 script:
 - cd core;
@@ -22,6 +25,7 @@ script:
 - travis-cargo test
 - travis-cargo --only stable test -- --features=deadlock_detection
 - travis-cargo --only beta test -- --features=deadlock_detection
+- travis-cargo --only nightly test -- --all --no-run --target x86_64-fortanix-unknown-sgx
 - travis-cargo --only nightly doc -- --all-features --no-deps -p parking_lot -p parking_lot_core -p lock_api
 - cd benchmark
 - travis-cargo build

core/src/lib.rs

@@ -39,17 +39,28 @@
 
 #![warn(missing_docs)]
 #![warn(rust_2018_idioms)]
+#![cfg_attr(
+    all(target_env = "sgx", target_vendor = "fortanix"),
+    feature(sgx_platform)
+)]
 
 #[cfg(all(feature = "nightly", target_os = "linux"))]
 #[path = "thread_parker/linux.rs"]
 mod thread_parker;
+
 #[cfg(all(unix, not(all(feature = "nightly", target_os = "linux"))))]
 #[path = "thread_parker/unix.rs"]
 mod thread_parker;
+
 #[cfg(windows)]
 #[path = "thread_parker/windows/mod.rs"]
 mod thread_parker;
-#[cfg(not(any(windows, unix)))]
+
+#[cfg(all(target_env = "sgx", target_vendor = "fortanix"))]
+#[path = "thread_parker/sgx.rs"]
+mod thread_parker;
+
+#[cfg(not(any(windows, unix, all(target_env = "sgx", target_vendor = "fortanix"))))]
 #[path = "thread_parker/generic.rs"]
 mod thread_parker;
 

core/src/thread_parker/sgx.rs

@@ -0,0 +1,108 @@
+// Copyright 2016 Amanieu d'Antras
+//
+// Licensed under the Apache License, Version 2.0, <LICENSE-APACHE or
+// http://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 core::sync::atomic::{AtomicBool, Ordering};
+use std::{
+    io,
+    os::fortanix_sgx::{
+        thread::current as current_tcs,
+        usercalls::{
+            self,
+            raw::{Tcs, EV_UNPARK, WAIT_INDEFINITE},
+        },
+    },
+    thread,
+    time::Instant,
+};
+
+// Helper type for putting a thread to sleep until some other thread wakes it up
+pub struct ThreadParker {
+    parked: AtomicBool,
+    tcs: Tcs,
+}
+
+impl ThreadParker {
+    pub const IS_CHEAP_TO_CONSTRUCT: bool = true;
+
+    #[inline]
+    pub fn new() -> ThreadParker {
+        ThreadParker {
+            parked: AtomicBool::new(false),
+            tcs: current_tcs(),
+        }
+    }
+
+    // Prepares the parker. This should be called before adding it to the queue.
+    #[inline]
+    pub fn prepare_park(&self) {
+        self.parked.store(true, Ordering::Relaxed);
+    }
+
+    // Checks if the park timed out. This should be called while holding the
+    // queue lock after park_until has returned false.
+    #[inline]
+    pub fn timed_out(&self) -> bool {
+        self.parked.load(Ordering::Relaxed)
+    }
+
+    // Parks the thread until it is unparked. This should be called after it has
+    // been added to the queue, after unlocking the queue.
+    #[inline]
+    pub fn park(&self) {
+        while self.parked.load(Ordering::Acquire) {
+            let result = usercalls::wait(EV_UNPARK, WAIT_INDEFINITE);
+            debug_assert_eq!(result.expect("wait returned error") & EV_UNPARK, EV_UNPARK);
+        }
+    }
+
+    // Parks the thread until it is unparked or the timeout is reached. This
+    // should be called after it has been added to the queue, after unlocking
+    // the queue. Returns true if we were unparked and false if we timed out.
+    #[inline]
+    pub fn park_until(&self, _timeout: Instant) -> bool {
+        // FIXME: https://github.com/fortanix/rust-sgx/issues/31
+        panic!("timeout not supported in SGX");
+    }
+
+    // Locks the parker to prevent the target thread from exiting. This is
+    // necessary to ensure that thread-local ThreadData objects remain valid.
+    // This should be called while holding the queue lock.
+    #[inline]
+    pub fn unpark_lock(&self) -> UnparkHandle {
+        // We don't need to lock anything, just clear the state
+        self.parked.store(false, Ordering::Release);
+        UnparkHandle(self.tcs)
+    }
+}
+
+// Handle for a thread that is about to be unparked. We need to mark the thread
+// as unparked while holding the queue lock, but we delay the actual unparking
+// until after the queue lock is released.
+pub struct UnparkHandle(Tcs);
+
+impl UnparkHandle {
+    // Wakes up the parked thread. This should be called after the queue lock is
+    // released to avoid blocking the queue for too long.
+    #[inline]
+    pub fn unpark(self) {
+        let result = usercalls::send(EV_UNPARK, Some(self.0));
+        if cfg!(debug_assertions) {
+            if let Err(error) = result {
+                // `InvalidInput` may be returned if the thread we send to has
+                // already been unparked and exited.
+                if error.kind() != io::ErrorKind::InvalidInput {
+                    panic!("send returned an unexpected error: {:?}", error);
+                }
+            }
+        }
+    }
+}
+
+#[inline]
+pub fn thread_yield() {
+    thread::yield_now();
+}

src/rwlock.rs

@@ -533,7 +533,15 @@ mod tests {
         thread::spawn(move || {
             let _lock = arc2.write();
         });
-        thread::sleep(Duration::from_millis(100));
+
+        if cfg!(not(all(target_env = "sgx", target_vendor = "fortanix"))) {
+            thread::sleep(Duration::from_millis(100));
+        } else {
+            // FIXME: https://github.com/fortanix/rust-sgx/issues/31
+            for _ in 0..100 {
+                thread::yield_now();
+            }
+        }
 
         // A normal read would block here since there is a pending writer
         let _lock2 = arc.read_recursive();