Bug 342737: New API to register JS_NewContext/JS_DestroyContext* callback. In this way an embedding can do a common customization of JSContext instances in a single place. r=brendan

js/src/jsapi.c

@@ -930,6 +930,16 @@ JS_Unlock(JSRuntime *rt)
     JS_UNLOCK_RUNTIME(rt);
 }
 
+JS_PUBLIC_API(JSContextCallback)
+JS_SetContextCallback(JSRuntime *rt, JSContextCallback cxCallback)
+{
+    JSContextCallback old;
+
+    old = rt->cxCallback;
+    rt->cxCallback = cxCallback;
+    return old;
+}
+
 JS_PUBLIC_API(JSContext *)
 JS_NewContext(JSRuntime *rt, size_t stackChunkSize)
 {
@@ -939,19 +949,19 @@ JS_NewContext(JSRuntime *rt, size_t stackChunkSize)
 JS_PUBLIC_API(void)
 JS_DestroyContext(JSContext *cx)
 {
-    js_DestroyContext(cx, JS_FORCE_GC);
+    js_DestroyContext(cx, JSDCM_FORCE_GC);
 }
 
 JS_PUBLIC_API(void)
 JS_DestroyContextNoGC(JSContext *cx)
 {
-    js_DestroyContext(cx, JS_NO_GC);
+    js_DestroyContext(cx, JSDCM_NO_GC);
 }
 
 JS_PUBLIC_API(void)
 JS_DestroyContextMaybeGC(JSContext *cx)
 {
-    js_DestroyContext(cx, JS_MAYBE_GC);
+    js_DestroyContext(cx, JSDCM_MAYBE_GC);
 }
 
 JS_PUBLIC_API(void *)

js/src/jsapi.h

@@ -437,6 +437,9 @@ JS_Lock(JSRuntime *rt);
 extern JS_PUBLIC_API(void)
 JS_Unlock(JSRuntime *rt);
 
+extern JS_PUBLIC_API(JSContextCallback)
+JS_SetContextCallback(JSRuntime *rt, JSContextCallback cxCallback);
+
 extern JS_PUBLIC_API(JSContext *)
 JS_NewContext(JSRuntime *rt, size_t stackChunkSize);
 

js/src/jscntxt.c

@@ -168,6 +168,7 @@ js_NewContext(JSRuntime *rt, size_t stackChunkSize)
 {
     JSContext *cx;
     JSBool ok, first;
+    JSContextCallback cxCallback;
 
     cx = (JSContext *) malloc(sizeof *cx);
     if (!cx)
@@ -214,7 +215,7 @@ js_NewContext(JSRuntime *rt, size_t stackChunkSize)
     JS_InitArenaPool(&cx->tempPool, "temp", 1024, sizeof(jsdouble));
 
     if (!js_InitRegExpStatics(cx, &cx->regExpStatics)) {
-        js_DestroyContext(cx, JS_NO_GC);
+        js_DestroyContext(cx, JSDCM_NEW_FAILED);
         return NULL;
     }
 
@@ -250,7 +251,7 @@ js_NewContext(JSRuntime *rt, size_t stackChunkSize)
         JS_EndRequest(cx);
 #endif
         if (!ok) {
-            js_DestroyContext(cx, JS_NO_GC);
+            js_DestroyContext(cx, JSDCM_NEW_FAILED);
             return NULL;
         }
 
@@ -260,13 +261,19 @@ js_NewContext(JSRuntime *rt, size_t stackChunkSize)
         JS_UNLOCK_GC(rt);
     }
 
+    cxCallback = rt->cxCallback;
+    if (cxCallback && !cxCallback(cx, JSCONTEXT_NEW)) {
+        js_DestroyContext(cx, JSDCM_NEW_FAILED);
+        return NULL;
+    }
     return cx;
 }
 
 void
-js_DestroyContext(JSContext *cx, JSGCMode gcmode)
+js_DestroyContext(JSContext *cx, JSDestroyContextMode mode)
 {
     JSRuntime *rt;
+    JSContextCallback cxCallback;
     JSBool last;
     JSArgumentFormatMap *map;
     JSLocalRootStack *lrs;
@@ -274,6 +281,21 @@ js_DestroyContext(JSContext *cx, JSGCMode gcmode)
 
     rt = cx->runtime;
 
+    if (mode != JSDCM_NEW_FAILED) {
+        cxCallback = rt->cxCallback;
+        if (cxCallback) {
+            /*
+             * JSCONTEXT_DESTROY callback is not allowed to fail and must
+             * return true.
+             */
+#ifdef DEBUG
+            JSBool callbackStatus =
+#endif
+            cxCallback(cx, JSCONTEXT_DESTROY);
+            JS_ASSERT(callbackStatus);
+        }
+    }
+
     /* Remove cx from context list first. */
     JS_LOCK_GC(rt);
     JS_ASSERT(rt->state == JSRTS_UP || rt->state == JSRTS_LAUNCHING);
@@ -357,9 +379,9 @@ js_DestroyContext(JSContext *cx, JSGCMode gcmode)
         JS_NOTIFY_ALL_CONDVAR(rt->stateChange);
         JS_UNLOCK_GC(rt);
     } else {
-        if (gcmode == JS_FORCE_GC)
+        if (mode == JSDCM_FORCE_GC)
             js_ForceGC(cx, 0);
-        else if (gcmode == JS_MAYBE_GC)
+        else if (mode == JSDCM_MAYBE_GC)
             JS_MaybeGC(cx);
     }
 

js/src/jscntxt.h

@@ -94,7 +94,12 @@ js_GetCurrentThread(JSRuntime *rt);
 
 #endif /* JS_THREADSAFE */
 
-typedef enum JSGCMode { JS_NO_GC, JS_MAYBE_GC, JS_FORCE_GC } JSGCMode;
+typedef enum JSDestroyContextMode {
+    JSDCM_NO_GC,
+    JSDCM_MAYBE_GC,
+    JSDCM_FORCE_GC,
+    JSDCM_NEW_FAILED
+} JSDestroyContextMode;
 
 typedef enum JSRuntimeState {
     JSRTS_DOWN,
@@ -117,6 +122,9 @@ struct JSRuntime {
     /* Runtime state, synchronized by the stateChange/gcLock condvar/lock. */
     JSRuntimeState      state;
 
+    /* Context create/destroy callback. */
+    JSContextCallback   cxCallback;
+
     /* Garbage collector state, used by jsgc.c. */
     JSGCArenaList       gcArenaList[GC_NUM_FREELISTS];
     JSDHashTable        gcRootsHash;
@@ -735,7 +743,7 @@ extern JSContext *
 js_NewContext(JSRuntime *rt, size_t stackChunkSize);
 
 extern void
-js_DestroyContext(JSContext *cx, JSGCMode gcmode);
+js_DestroyContext(JSContext *cx, JSDestroyContextMode mode);
 
 /*
  * Return true if cx points to a context in rt->contextList, else return false.

js/src/jspubtd.h

@@ -541,6 +541,27 @@ typedef JSBool
 
 /* Callbacks and their arguments. */
 
+typedef enum JSContextOp {
+    JSCONTEXT_NEW,
+    JSCONTEXT_DESTROY
+} JSContextOp;
+
+/*
+ * The possible values for contextOp when the runtime calls the callback are:
+ *   JSCONTEXT_NEW      JS_NewContext succesfully created a new JSContext
+ *                      instance. The callback can initialize the instance as
+ *                      required. If the callback returns false, the instance
+ *                      will be destroyed and JS_NewContext returns null. In
+ *                      this case the callback is not called again.
+ *   JSCONTEXT_DESTROY  One of JS_DestroyContext* methods is called. The
+ *                      callback may perform its own cleanup and must always
+ *                      return true.
+ *   Any other value    For future compatibility the callback must do nothing
+ *                      and return true in this case.
+ */
+typedef JSBool
+(* JS_DLL_CALLBACK JSContextCallback)(JSContext *cx, uintN contextOp);
+
 typedef enum JSGCStatus {
     JSGC_BEGIN,
     JSGC_END,