--- a/hotspot/src/os/linux/vm/os_linux.cpp Thu Jul 03 09:16:56 2014 -0700
+++ b/hotspot/src/os/linux/vm/os_linux.cpp Thu Jul 03 11:07:51 2014 -0700
@@ -5457,22 +5457,12 @@
return abstime;
}
-
-// Test-and-clear _Event, always leaves _Event set to 0, returns immediately.
-// Conceptually TryPark() should be equivalent to park(0).
-
-int os::PlatformEvent::TryPark() {
- for (;;) {
- const int v = _Event;
- guarantee((v == 0) || (v == 1), "invariant");
- if (Atomic::cmpxchg(0, &_Event, v) == v) return v;
- }
-}
-
void os::PlatformEvent::park() { // AKA "down()"
// Invariant: Only the thread associated with the Event/PlatformEvent
// may call park().
// TODO: assert that _Assoc != NULL or _Assoc == Self
+ assert(_nParked == 0, "invariant");
+
int v;
for (;;) {
v = _Event;
@@ -5572,8 +5562,7 @@
// 1 :=> 1
// -1 :=> either 0 or 1; must signal target thread
// That is, we can safely transition _Event from -1 to either
- // 0 or 1. Forcing 1 is slightly more efficient for back-to-back
- // unpark() calls.
+ // 0 or 1.
// See also: "Semaphores in Plan 9" by Mullender & Cox
//
// Note: Forcing a transition from "-1" to "1" on an unpark() means
@@ -5801,10 +5790,9 @@
}
void Parker::unpark() {
- int s, status;
- status = pthread_mutex_lock(_mutex);
+ int status = pthread_mutex_lock(_mutex);
assert(status == 0, "invariant");
- s = _counter;
+ const int s = _counter;
_counter = 1;
if (s < 1) {
// thread might be parked