Merge branch 'fibers' of https://github.com/openjdk/loom into fibers

src/jdk.jdwp.agent/share/native/libjdwp/debugInit.c

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1998, 2020, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1998, 2021, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -876,7 +876,9 @@ printUsage(void)
  "onthrow=<exception name>         debug on throw                    none\n"
  "onuncaught=y|n                   debug on any uncaught?            n\n"
  "timeout=<timeout value>          for listen/attach in milliseconds n\n"
- "virtualthreads=y|n|all           support debugging virtual threads y\n"
+ "trackvthreads=some|all           track some or all vthreads        some\n"
+ "enumeratevthreads=y|n            thread lists include vthreads     y\n"
+ "fakevthreadstartevent=y|n        send fake start event when needed y\n"
  "mutf8=y|n                        output modified utf-8             n\n"
  "quiet=y|n                        control over terminal messages    n\n"));
 
@@ -1025,7 +1027,9 @@ parseOptions(char *options)
 
     /* Set vthread debugging level. */
     gdata->vthreadsSupported = JNI_TRUE;
-    gdata->notifyDebuggerOfAllVThreads = JNI_FALSE;
+    gdata->trackAllVThreads = JNI_FALSE;
+    gdata->enumerateVThreads = JNI_TRUE;
+    gdata->fakeVThreadStartEvent = JNI_TRUE;
 
     /* Options being NULL will end up being an error. */
     if (options == NULL) {
@@ -1129,19 +1133,38 @@ parseOptions(char *options)
             }
             currentTransport->timeout = atol(current);
             current += strlen(current) + 1;
-        } else if (strcmp(buf, "virtualthreads") == 0) {
+        } else if (strcmp(buf, "trackvthreads") == 0) {
             if (!get_tok(&str, current, (int)(end - current), ',')) {
                 goto syntax_error;
             }
-            if (strcmp(current, "y") == 0) {
-                gdata->vthreadsSupported = JNI_TRUE;
-                gdata->notifyDebuggerOfAllVThreads = JNI_FALSE;
+            if (strcmp(current, "some") == 0) {
+                gdata->trackAllVThreads = JNI_FALSE;
             } else if (strcmp(current, "all") == 0) {
-                gdata->vthreadsSupported = JNI_TRUE;
-                gdata->notifyDebuggerOfAllVThreads = JNI_TRUE;
+                gdata->trackAllVThreads = JNI_TRUE;
+            } else {
+                goto syntax_error;
+            }
+            current += strlen(current) + 1;
+        } else if (strcmp(buf, "enumeratevthreads") == 0) {
+            if (!get_tok(&str, current, (int)(end - current), ',')) {
+                goto syntax_error;
+            }
+            if (strcmp(current, "y") == 0) {
+                gdata->enumerateVThreads = JNI_TRUE;
+            } else if (strcmp(current, "n") == 0) {
+                gdata->enumerateVThreads = JNI_FALSE;
+            } else {
+                goto syntax_error;
+            }
+            current += strlen(current) + 1;
+        } else if (strcmp(buf, "fakevthreadstartevent") == 0) {
+            if (!get_tok(&str, current, (int)(end - current), ',')) {
+                goto syntax_error;
+            }
+            if (strcmp(current, "y") == 0) {
+                gdata->fakeVThreadStartEvent = JNI_TRUE;
             } else if (strcmp(current, "n") == 0) {
-                gdata->vthreadsSupported = JNI_FALSE;
-                gdata->notifyDebuggerOfAllVThreads = JNI_FALSE;
+                gdata->fakeVThreadStartEvent = JNI_FALSE;
             } else {
                 goto syntax_error;
             }

src/jdk.jdwp.agent/share/native/libjdwp/eventHandler.c

@@ -647,25 +647,29 @@ filterAndAddVThread(JNIEnv *env, EventInfo *evinfo, EventIndex ei, jbyte eventSe
         /* Make sure this vthread gets added to the vthreads list. */
         threadControl_addVThread(vthread);
 
-        /*
-         * When the VIRTUAL_THREAD_SCHEDULED event arrived for this vthread, we ignored it since we don't
-         * want to notify the debugger about vthreads until there is a non-vthread event that
-         * arrives on it (like a breakpoint). Now that this has happened, we need to send
-         * a VIRTUAL_THREAD_SCHEDULED event (which will be converted into a THREAD_START event) so
-         * the debugger will know about the vthread. Otherwise it will be unhappy when it gets
-         * an event for a vthread that it never got a THREAD_START event for.
-         */
-        EventInfo info;
-        struct bag *eventBag = eventHelper_createEventBag();
-
-        (void)memset(&info,0,sizeof(info));
-        info.ei         = EI_VIRTUAL_THREAD_SCHEDULED;
-        info.thread     = vthread;
-
-        /* Note: filterAndHandleEvent() expects EI_THREAD_START instead of EI_VIRTUAL_THREAD_SCHEDULED. */
-        filterAndHandleEvent(env, &info, EI_THREAD_START, eventBag, eventSessionID);
-        JDI_ASSERT(bagSize(eventBag) == 0);
-        bagDestroyBag(eventBag);
+        if (gdata->fakeVThreadStartEvent) {
+            /* vthread fixme: this shouldn't be needed if ei == EI_THREAD_START. */
+            /*
+             * When the VIRTUAL_THREAD_SCHEDULED event arrived for this vthread, we ignored it since we don't
+             * want to notify the debugger about vthreads until there is a non-vthread event that
+             * arrives on it (like a breakpoint). Now that this has happened, we need to send
+             * a VIRTUAL_THREAD_SCHEDULED event (which will be converted into a THREAD_START event) so
+             * the debugger will know about the vthread. Otherwise it will be unhappy when it gets
+             * an event for a vthread that it never got a THREAD_START event for.
+             */
+            EventInfo info;
+            struct bag *eventBag = eventHelper_createEventBag();
+
+            (void)memset(&info,0,sizeof(info));
+            info.ei         = EI_VIRTUAL_THREAD_SCHEDULED;
+            info.thread     = vthread;
+
+            /* Note: filterAndHandleEvent() expects EI_THREAD_START instead of EI_VIRTUAL_THREAD_SCHEDULED
+             * in order for getHandlerChain(ei) to work properly. */
+            filterAndHandleEvent(env, &info, EI_THREAD_START, eventBag, eventSessionID);
+            JDI_ASSERT(bagSize(eventBag) == 0);
+            bagDestroyBag(eventBag);
+        }
     }
 }
 
@@ -784,9 +788,13 @@ event_callback(JNIEnv *env, EventInfo *evinfo)
     if (gdata->vthreadsSupported) {
         /* Add the vthread if we haven't added it before. */
         if (evinfo->is_vthread && !threadControl_isKnownVThread(thread)) {
-            if (gdata->notifyDebuggerOfAllVThreads) {
+            if (gdata->trackAllVThreads) {
                 /* Make sure this vthread gets added to the vthreads list. */
                 threadControl_addVThread(thread);
+                /* vthread fixme: we need to fake a THREAD_START event here just like
+                 * filterAndAddVThread() does. This is needed when the debug
+                 * agent is started after some vthreads have already been started.
+                 */
             } else {
                 /* Add this vthread if it passes the event filters. */
                 filterAndAddVThread(env, evinfo, ei, eventSessionID);
@@ -1448,6 +1456,11 @@ cbVThreadScheduled(jvmtiEnv *jvmti_env, JNIEnv *env,
         }
     }
 
+    /* Ignore VIRTUAL_THREAD_SCHEDULED events unless we are notifying the debugger of all vthreads. */
+    if (!gdata->trackAllVThreads || !gdata->enumerateVThreads) {
+        return;
+    }
+
     BEGIN_CALLBACK() {
         (void)memset(&info,0,sizeof(info));
         info.ei         = EI_THREAD_START;

src/jdk.jdwp.agent/share/native/libjdwp/threadControl.c

@@ -2691,6 +2691,11 @@ threadControl_allVThreads(jint *numVThreads)
     ThreadNode *node;
     jthread* vthreads;
 
+    if (!gdata->enumerateVThreads) {
+      *numVThreads = 0;
+      return NULL;
+    }
+
     env = getEnv();
     debugMonitorEnter(threadLock);
 

src/jdk.jdwp.agent/share/native/libjdwp/util.h

@@ -83,10 +83,10 @@ typedef struct {
     volatile jboolean vmDead; /* Once VM is dead it stays that way - don't put in init */
     jboolean assertOn;
     jboolean assertFatal;
-    jboolean vthreadsSupported;      /* If true, debugging support for vthreads is enabled.*/
-    jboolean notifyDebuggerOfAllVThreads; /* If true, the debugger will be notified of all known vthreads.
-                                           * If false the debugger is only notified of vthreads for which
-                                           * certain events have been received. */
+    jboolean vthreadsSupported; /* If true, debugging support for vthreads is enabled.*/
+    jboolean trackAllVThreads;  /* If true, track all vthreads. Otherwise just ones we get events on. */
+    jboolean enumerateVThreads; /* If true, JDWP APIs return tracked vthreads in thread lists. Otherwise they don't. */
+    jboolean fakeVThreadStartEvent; /* If true, send a fake THREAD_START event the first time we get an event on a vthread. */
     jboolean doerrorexit;
     jboolean modifiedUtf8;
     jboolean quiet;