From: Jack Lange <jarusl@cs.northwestern.edu>
Date: Mon, 29 Sep 2008 16:07:55 +0000 (-0500)
Subject: added support for timing out Cond_Wait's
X-Git-Tag: 1.0~3^2~11^2~4^2
X-Git-Url: http://v3vee.org/palacios/gitweb/gitweb.cgi?a=commitdiff_plain;h=ac9621026b54c3b5e9bae3d7153736c65ab03652;p=palacios.git

added support for timing out Cond_Wait's
also added support for waking up specific threads by pid
---

diff --git a/palacios/include/geekos/kthread.h b/palacios/include/geekos/kthread.h
index f0ef23c..48ade1c 100644
--- a/palacios/include/geekos/kthread.h
+++ b/palacios/include/geekos/kthread.h
@@ -123,6 +123,7 @@ void Switch_To_Thread(struct Kernel_Thread*);
 void Wait(struct Thread_Queue* waitQueue);
 void Wake_Up(struct Thread_Queue* waitQueue);
 void Wake_Up_One(struct Thread_Queue* waitQueue);
+void Wake_Up_Thread(struct Thread_Queue* waitQueue, int pid);
 
 /*
  * Pointer to currently executing thread.
diff --git a/palacios/include/geekos/synch.h b/palacios/include/geekos/synch.h
index 5cb95ef..b1ad875 100644
--- a/palacios/include/geekos/synch.h
+++ b/palacios/include/geekos/synch.h
@@ -18,9 +18,9 @@
 enum { MUTEX_UNLOCKED, MUTEX_LOCKED };
 
 struct Mutex {
-    int state;
-    struct Kernel_Thread* owner;
-    struct Thread_Queue waitQueue;
+  int state;
+  struct Kernel_Thread* owner;
+  struct Thread_Queue waitQueue;
 };
 
 #define MUTEX_INITIALIZER { MUTEX_UNLOCKED, 0, THREAD_QUEUE_INITIALIZER }
@@ -35,6 +35,7 @@ void Mutex_Unlock(struct Mutex* mutex);
 
 void Cond_Init(struct Condition* cond);
 void Cond_Wait(struct Condition* cond, struct Mutex* mutex);
+int Cond_Wait_Timeout(struct Condition * cond, struct Mutex * mutex, uint_t ms);
 void Cond_Signal(struct Condition* cond);
 void Cond_Broadcast(struct Condition* cond);
 
diff --git a/palacios/src/geekos/kthread.c b/palacios/src/geekos/kthread.c
index 0cba546..6ecb30f 100644
--- a/palacios/src/geekos/kthread.c
+++ b/palacios/src/geekos/kthread.c
@@ -748,6 +748,30 @@ void Wake_Up_One(struct Thread_Queue* waitQueue)
     }
 }
 
+
+
+/*
+ * Wake up a single thread waiting on given wait queue
+ * (if there are any threads waiting).  Chooses the highest priority thread.
+ * Interrupts must be disabled!
+ */
+void Wake_Up_Thread(struct Thread_Queue* waitQueue, int pid)
+{
+  struct Kernel_Thread* thread = Lookup_Thread(pid);;
+
+  KASSERT(!Interrupts_Enabled());
+  
+  
+  if (thread != 0) {
+    Remove_Thread(waitQueue, thread);
+    Make_Runnable(thread);
+	/*Print("Wake_Up_One: waking up %x from %x\n", best, g_currentThread); */
+  }
+}
+
+
+
+
 /*
  * Allocate a key for accessing thread-local data.
  */
diff --git a/palacios/src/geekos/synch.c b/palacios/src/geekos/synch.c
index 86e7191..fdc1f34 100644
--- a/palacios/src/geekos/synch.c
+++ b/palacios/src/geekos/synch.c
@@ -12,6 +12,7 @@
 #include <geekos/kassert.h>
 #include <geekos/screen.h>
 #include <geekos/synch.h>
+#include <geekos/timer.h>
 
 /*
  * NOTES:
@@ -181,6 +182,82 @@ void Cond_Wait(struct Condition* cond, struct Mutex* mutex)
     g_preemptionDisabled = false;
 }
 
+
+
+struct timeout_data {
+  int pid;
+  int timed_out;
+  struct Thread_Queue * waitQueue;
+};
+
+
+static void timeout_cb(int id, void * arg) {
+  struct timeout_data * to_state = (struct timeout_data *)arg;
+  
+  to_state->timed_out = 1;
+  Wake_Up_Thread(to_state->waitQueue, to_state->pid);
+
+}
+
+
+/*
+ * Wait on given condition (protected by given mutex).
+ */
+int Cond_Wait_Timeout(struct Condition* cond, struct Mutex* mutex, uint_t ms)
+{
+  struct timeout_data to_state;
+  struct Kernel_Thread * self = Get_Current();
+
+  to_state.pid = self->pid;
+  to_state.timed_out = 0;
+  to_state.waitQueue = &cond->waitQueue;
+
+    KASSERT(Interrupts_Enabled());
+
+    /* Ensure mutex is held. */
+    KASSERT(IS_HELD(mutex));
+
+    /* Turn off scheduling. */
+    g_preemptionDisabled = true;
+
+
+
+    /*
+     * Release the mutex, but leave preemption disabled.
+     * No other threads will be able to run before this thread
+     * is able to wait.  Therefore, this thread will not
+     * miss the eventual notification on the condition.
+     */
+    Mutex_Unlock_Imp(mutex);
+
+
+    Start_Timer_MSecs(ms, timeout_cb, &to_state);
+
+    /*
+     * Atomically reenable preemption and wait in the condition wait queue.
+     * Other threads can run while this thread is waiting,
+     * and eventually one of them will call Cond_Signal() or Cond_Broadcast()
+     * to wake up this thread.
+     * On wakeup, disable preemption again.
+     */
+    Disable_Interrupts();
+    g_preemptionDisabled = false;
+    Wait(&cond->waitQueue);
+    g_preemptionDisabled = true;
+    Enable_Interrupts();
+
+    if (to_state.timed_out == 0) {  
+      /* Reacquire the mutex. */
+      Mutex_Lock_Imp(mutex);
+    }
+
+    /* Turn scheduling back on. */
+    g_preemptionDisabled = false;
+
+
+    return to_state.timed_out;
+}
+
 /*
  * Wake up one thread waiting on the given condition.
  * The mutex guarding the condition should be held!