CRIU supports Java debugger during checkpoint and restore

Added support for a VM_RESTORE JVMTI event;
Added an additional command line option suspendOnRestore=[y|n] to
determine if the VM restored from a checkpoint is to be suspended;
-agentlib:jdwp=transport=dt_socket,server=y,suspend=[y|n] assumes
suspendOnRestore=y;
Always respect suspendOnRestore=n regardless the order of suspend and
suspendOnRestore, both
-agentlib:jdwp=transport=dt_socket,server=y,suspendOnRestore=n,suspend=y
and -agentlib:jdwp=transport=dt_socket,server=y,suspend=y,suspendOnRestore=n
don't suspend the JVM post-restore.

Signed-off-by: Mike Zhang <[email protected]>
Signed-off-by: Jason Feng <[email protected]>

closed/GensrcJ9JCL.gmk

@@ -1,5 +1,5 @@
 # ===========================================================================
-# (c) Copyright IBM Corp. 2020, 2023 All Rights Reserved
+# (c) Copyright IBM Corp. 2020, 2024 All Rights Reserved
 # ===========================================================================
 # This code is free software; you can redistribute it and/or modify it
 # under the terms of the GNU General Public License version 2 only, as
@@ -39,6 +39,7 @@ $(eval $(call SetupCopyFiles,COPY_OVERLAY_FILES, \
 	SRC := $(TOPDIR), \
 	DEST := $(SUPPORT_OUTPUTDIR)/overlay, \
 	FILES := \
+		make/data/jdwp/jdwp.spec \
 		src/java.base/share/classes/com/sun/crypto/provider/HmacCore.java \
 		src/java.base/share/classes/java/lang/ClassValue.java \
 		src/java.base/share/classes/java/lang/invoke/ClassSpecializer.java \
@@ -56,6 +57,13 @@ $(eval $(call SetupCopyFiles,COPY_OVERLAY_FILES, \
 		src/java.base/share/classes/sun/security/provider/SecureRandom.java \
 		src/java.base/unix/classes/java/lang/ProcessEnvironment.java \
 		src/java.base/unix/classes/sun/security/provider/NativePRNG.java \
+		src/jdk.jdi/share/classes/com/sun/tools/example/debug/tty/EventHandler.java \
+		src/jdk.jdi/share/classes/com/sun/tools/example/debug/tty/EventNotifier.java \
+		src/jdk.jdi/share/classes/com/sun/tools/example/debug/tty/TTY.java \
+		src/jdk.jdi/share/classes/com/sun/tools/example/debug/tty/TTYResources.java \
+		src/jdk.jdi/share/classes/com/sun/tools/example/debug/tty/TTYResources_ja.java \
+		src/jdk.jdi/share/classes/com/sun/tools/example/debug/tty/TTYResources_zh_CN.java \
+		src/jdk.jdi/share/classes/com/sun/tools/jdi/EventSetImpl.java \
 	))
 
 IncludeIfUnsure := -includeIfUnsure -noWarnIncludeIf

closed/src/jdk.jdi/share/classes/com/sun/jdi/event/VMRestoreEvent.java

@@ -0,0 +1,50 @@
+/*[INCLUDE-IF CRIU_SUPPORT]*/
+/*
+ * ===========================================================================
+ * (c) Copyright IBM Corp. 2023, 2024 All Rights Reserved
+ * ===========================================================================
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * IBM designates this particular file as subject to the "Classpath" exception
+ * as provided by IBM in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, see <http://www.gnu.org/licenses/>.
+ *
+ * ===========================================================================
+ */
+package com.sun.jdi.event;
+
+import com.sun.jdi.ThreadReference;
+import com.sun.jdi.VirtualMachine;
+
+/**
+ * Notification of when the VM is restored from a checkpoint. Similar to
+ * VMStartEvent this occurs before application code has run, including any
+ * application hooks for the restore event.
+ * The event is generated even if not explicitly requested.
+ *
+ * @see VMStartEvent
+ * @see VMDeathEvent
+ * @see EventQueue
+ * @see VirtualMachine
+ */
+public interface VMRestoreEvent extends Event {
+
+    /**
+     * Returns the thread which is restoring the VM from a checkpoint.
+     *
+     * @return a {@link ThreadReference} representing the restore thread
+     * on the target VM.
+     */
+    public ThreadReference thread();
+}

make/data/jdwp/jdwp.spec

@@ -23,6 +23,12 @@
  * questions.
  */
 
+/*
+ * ===========================================================================
+ * (c) Copyright IBM Corp. 2023, 2024 All Rights Reserved
+ * ===========================================================================
+ */
+
 JDWP "Java(tm) Debug Wire Protocol"
 (CommandSet VirtualMachine=1
     (Command Version=1
@@ -3090,6 +3096,17 @@ JDWP "Java(tm) Debug Wire Protocol"
                         (int requestID
                                 "Request that generated event")
                     )
+/*[IF CRIU_SUPPORT]*/
+                    (Alt VMRestore=JDWP.EventKind.VM_RESTORE
+                        "Notification of when the VM is restored from a checkpoint. Similar to"
+                        "VMStartEvent this occurs before application code has run, including any"
+                        "application hooks for the restore event."
+                        "The event is generated even if not explicitly requested."
+
+                        (int requestID "Request that generated event")
+                        (threadObject thread "The thread restoring the VM from a checkpoint.")
+                    )
+/*[ENDIF] CRIU_SUPPORT */
                 )
             )
         )
@@ -3219,6 +3236,9 @@ JDWP "Java(tm) Debug Wire Protocol"
     (Constant VM_INIT                =90  "obsolete - was used in jvmdi")
     (Constant VM_DEATH               =99  )
     (Constant VM_DISCONNECTED        =100 "Never sent across JDWP")
+/*[IF CRIU_SUPPORT]*/
+    (Constant VM_RESTORE             =101 "OpenJ9 VM Restored")
+/*[ENDIF] CRIU_SUPPORT */
 )
 
 (ConstantSet ThreadStatus

src/jdk.jdi/share/classes/com/sun/tools/example/debug/tty/EventHandler.java

@@ -31,6 +31,11 @@
  * this sample code.
  */
 
+/*
+ * ===========================================================================
+ * (c) Copyright IBM Corp. 2023, 2024 All Rights Reserved
+ * ===========================================================================
+ */
 
 package com.sun.tools.example.debug.tty;
 
@@ -118,6 +123,10 @@ private boolean handleEvent(Event event) {
             return threadDeathEvent(event);
         } else if (event instanceof VMStartEvent) {
             return vmStartEvent(event);
+/*[IF CRIU_SUPPORT]*/
+        } else if (event instanceof VMRestoreEvent restoreEvent) {
+            return vmRestoreEvent(restoreEvent);
+/*[ENDIF] CRIU_SUPPORT */
         } else {
             return handleExitEvent(event);
         }
@@ -179,6 +188,10 @@ private ThreadReference eventThread(Event event) {
             return ((ThreadDeathEvent)event).thread();
         } else if (event instanceof VMStartEvent) {
             return ((VMStartEvent)event).thread();
+/*[IF CRIU_SUPPORT]*/
+        } else if (event instanceof VMRestoreEvent restoreEvent) {
+            return restoreEvent.thread();
+/*[ENDIF] CRIU_SUPPORT */
         } else {
             return null;
         }
@@ -210,6 +223,13 @@ private boolean vmStartEvent(Event event)  {
         return stopOnVMStart;
     }
 
+/*[IF CRIU_SUPPORT]*/
+    private boolean vmRestoreEvent(VMRestoreEvent restoreEvent) {
+        notifier.vmRestoreEvent(restoreEvent);
+        return stopOnVMStart;
+    }
+/*[ENDIF] CRIU_SUPPORT */
+
     private boolean breakpointEvent(Event event)  {
         BreakpointEvent be = (BreakpointEvent)event;
         notifier.breakpointEvent(be);

src/jdk.jdi/share/classes/com/sun/tools/example/debug/tty/EventNotifier.java

@@ -23,6 +23,12 @@
  * questions.
  */
 
+/*
+ * ===========================================================================
+ * (c) Copyright IBM Corp. 2023, 2024 All Rights Reserved
+ * ===========================================================================
+ */
+
 /*
  * This source code is provided to illustrate the usage of a given feature
  * or technique and has been deliberately simplified. Additional steps
@@ -38,6 +44,9 @@
 
 interface EventNotifier {
     void vmStartEvent(VMStartEvent e);
+/*[IF CRIU_SUPPORT]*/
+    void vmRestoreEvent(VMRestoreEvent e);
+/*[ENDIF] CRIU_SUPPORT */
     void vmDeathEvent(VMDeathEvent e);
     void vmDisconnectEvent(VMDisconnectEvent e);
 

src/jdk.jdi/share/classes/com/sun/tools/example/debug/tty/TTY.java

@@ -23,6 +23,12 @@
  * questions.
  */
 
+/*
+ * ===========================================================================
+ * (c) Copyright IBM Corp. 2023, 2024 All Rights Reserved
+ * ===========================================================================
+ */
+
 /*
  * This source code is provided to illustrate the usage of a given feature
  * or technique and has been deliberately simplified. Additional steps
@@ -73,6 +79,14 @@ public void vmStartEvent(VMStartEvent se)  {
         MessageOutput.lnprint("VM Started:");
     }
 
+/*[IF CRIU_SUPPORT]*/
+    @Override
+    public void vmRestoreEvent(VMRestoreEvent re) {
+        Thread.yield(); // fetch output
+        MessageOutput.lnprint("VM Restored:");
+    }
+/*[ENDIF] CRIU_SUPPORT */
+
     @Override
     public void vmDeathEvent(VMDeathEvent e)  {
     }

src/jdk.jdi/share/classes/com/sun/tools/example/debug/tty/TTYResources.java

@@ -23,6 +23,12 @@
  * questions.
  */
 
+/*
+ * ===========================================================================
+ * (c) Copyright IBM Corp. 2023, 2024 All Rights Reserved
+ * ===========================================================================
+ */
+
 /*
  * This source code is provided to illustrate the usage of a given feature
  * or technique and has been deliberately simplified. Additional steps
@@ -484,6 +490,9 @@ public Object[][] getContents() {
              "<arguments> are the arguments passed to the main() method of <class>\n" +
              "\n" +
              "For command help type ''help'' at {0} prompt"},
+/*[IF CRIU_SUPPORT]*/
+        {"VM Restored:", "VM restored from checkpoint:"},
+/*[ENDIF] CRIU_SUPPORT */
         // END OF MATERIAL TO LOCALIZE
         };