bug 561657 - Replacing js_CountThreadRequests with an explicit counter. r=jorendorff

js/src/jsapi.cpp

@@ -780,6 +780,7 @@ JS_BeginRequest(JSContext *cx)
 
         /* Indicate that a request is running. */
         rt->requestCount++;
+        cx->thread->contextsInRequests++;
         cx->requestDepth = 1;
         cx->outstandingRequests++;
         return;
@@ -799,12 +800,14 @@ JS_EndRequest(JSContext *cx)
     JS_ASSERT(CURRENT_THREAD_IS_ME(cx->thread));
     JS_ASSERT(cx->requestDepth > 0);
     JS_ASSERT(cx->outstandingRequests > 0);
+    JS_ASSERT(cx->thread->contextsInRequests > 0);
     if (cx->requestDepth == 1) {
         LeaveTrace(cx);  /* for GC safety */
 
         /* Lock before clearing to interlock with ClaimScope, in jslock.c. */
         rt = cx->runtime;
         AutoLockGC lock(rt);
+
         cx->requestDepth = 0;
         cx->outstandingRequests--;
 
@@ -813,11 +816,11 @@ JS_EndRequest(JSContext *cx)
         /* Give the GC a chance to run if this was the last request running. */
         JS_ASSERT(rt->requestCount > 0);
         rt->requestCount--;
+        cx->thread->contextsInRequests--;
         if (rt->requestCount == 0)
             JS_NOTIFY_REQUEST_DONE(rt);
         return;
     }
-
     cx->requestDepth--;
     cx->outstandingRequests--;
 #endif

js/src/jscntxt.cpp

@@ -1247,48 +1247,6 @@ js_NextActiveContext(JSRuntime *rt, JSContext *cx)
 #endif
 }
 
-#ifdef JS_THREADSAFE
-
-uint32
-js_CountThreadRequests(JSContext *cx)
-{
-    JSCList *head, *link;
-    uint32 nrequests;
-
-    JS_ASSERT(CURRENT_THREAD_IS_ME(cx->thread));
-    head = &cx->thread->contextList;
-    nrequests = 0;
-    for (link = head->next; link != head; link = link->next) {
-        JSContext *acx = CX_FROM_THREAD_LINKS(link);
-        JS_ASSERT(acx->thread == cx->thread);
-        if (acx->requestDepth)
-            nrequests++;
-    }
-    return nrequests;
-}
-
-/*
- * If the GC is running and we're called on another thread, wait for this GC
- * activation to finish. We can safely wait here without fear of deadlock (in
- * the case where we are called within a request on another thread's context)
- * because the GC doesn't set rt->gcRunning until after it has waited for all
- * active requests to end.
- *
- * We call here js_CurrentThreadId() after checking for rt->gcRunning to avoid
- * expensive calls when the GC is not running.
- */
-void
-js_WaitForGC(JSRuntime *rt)
-{
-    if (rt->gcRunning && rt->gcThread->id != js_CurrentThreadId()) {
-        do {
-            JS_AWAIT_GC_DONE(rt);
-        } while (rt->gcRunning);
-    }
-}
-
-#endif
-
 static JSDHashNumber
 resolving_HashKey(JSDHashTable *table, const void *ptr)
 {

js/src/jscntxt.h

@@ -1076,6 +1076,12 @@ struct JSThread {
      */
     bool                gcWaiting;
 
+    /*
+     * Number of JSContext instances that are in requests on this thread. For
+     * such instances JSContext::requestDepth > 0 holds.
+     */
+    uint32              contextsInRequests;
+
     /* Factored out of JSThread for !JS_THREADSAFE embedding in JSRuntime. */
     JSThreadData        data;
 };
@@ -2705,29 +2711,6 @@ js_ContextIterator(JSRuntime *rt, JSBool unlocked, JSContext **iterp);
 extern JS_FRIEND_API(JSContext *)
 js_NextActiveContext(JSRuntime *, JSContext *);
 
-#ifdef JS_THREADSAFE
-
-/*
- * Count the number of contexts entered requests on the current thread.
- */
-extern uint32
-js_CountThreadRequests(JSContext *cx);
-
-/*
- * This is a helper for code at can potentially run outside JS request to
- * ensure that the GC is not running when the function returns.
- *
- * This function must be called with the GC lock held.
- */
-extern void
-js_WaitForGC(JSRuntime *rt);
-
-#else /* !JS_THREADSAFE */
-
-# define js_WaitForGC(rt)    ((void) 0)
-
-#endif
-
 /*
  * JSClass.resolve and watchpoint recursion damping machinery.
  */

js/src/jsgc.cpp

@@ -2941,6 +2941,27 @@ GC(JSContext *cx  GCTIMER_PARAM)
 }
 
 #ifdef JS_THREADSAFE
+
+/*
+ * If the GC is running and we're called on another thread, wait for this GC
+ * activation to finish. We can safely wait here without fear of deadlock (in
+ * the case where we are called within a request on another thread's context)
+ * because the GC doesn't set rt->gcRunning until after it has waited for all
+ * active requests to end.
+ *
+ * We call here js_CurrentThreadId() after checking for rt->gcState to avoid
+ * an expensive call when the GC is not running.
+ */
+void
+js_WaitForGC(JSRuntime *rt)
+{
+    if (rt->gcRunning && rt->gcThread->id != js_CurrentThreadId()) {
+        do {
+            JS_AWAIT_GC_DONE(rt);
+        } while (rt->gcRunning);
+    }
+}
+
 /*
  * GC is running on another thread. Temporarily suspend all requests running
  * on the current thread and wait until the GC is done.
@@ -2952,7 +2973,7 @@ LetOtherGCFinish(JSContext *cx)
     JS_ASSERT(rt->gcThread);
     JS_ASSERT(cx->thread != rt->gcThread);
 
-    size_t requestDebit = js_CountThreadRequests(cx);
+    size_t requestDebit = cx->thread->contextsInRequests;
     JS_ASSERT(requestDebit <= rt->requestCount);
 #ifdef JS_TRACER
     JS_ASSERT_IF(requestDebit == 0, !JS_ON_TRACE(cx));
@@ -3034,7 +3055,7 @@ BeginGCSession(JSContext *cx)
      * JS_NOTIFY_REQUEST_DONE, which will wake us up, is only called on
      * rt->requestCount transitions to 0.
      */
-    size_t requestDebit = js_CountThreadRequests(cx);
+    size_t requestDebit = cx->thread->contextsInRequests;
     JS_ASSERT_IF(cx->requestDepth != 0, requestDebit >= 1);
     JS_ASSERT(requestDebit <= rt->requestCount);
     if (requestDebit != rt->requestCount) {

js/src/jsgc.h

@@ -227,6 +227,22 @@ extern bool
 js_SetProtoOrParentCheckingForCycles(JSContext *cx, JSObject *obj,
                                      uint32 slot, JSObject *pobj);
 
+#ifdef JS_THREADSAFE
+/*
+ * This is a helper for code at can potentially run outside JS request to
+ * ensure that the GC is not running when the function returns.
+ *
+ * This function must be called with the GC lock held.
+ */
+extern void
+js_WaitForGC(JSRuntime *rt);
+
+#else /* !JS_THREADSAFE */
+
+# define js_WaitForGC(rt)    ((void) 0)
+
+#endif
+
 extern void
 js_CallGCMarker(JSTracer *trc, void *thing, uint32 kind);