feat(diagnostics): implement endpoint for JMX threadinfo dump

src/main/java/io/cryostat/diagnostic/Diagnostics.java

@@ -15,14 +15,24 @@
  */
 package io.cryostat.diagnostic;
 
+import java.lang.management.ThreadInfo;
+import java.util.ArrayList;
+import java.util.List;
+
+import javax.management.openmbean.CompositeData;
+
 import io.cryostat.targets.Target;
 import io.cryostat.targets.TargetConnectionManager;
 
+import com.fasterxml.jackson.annotation.JsonValue;
 import io.smallrye.common.annotation.Blocking;
 import jakarta.annotation.security.RolesAllowed;
 import jakarta.inject.Inject;
+import jakarta.ws.rs.GET;
 import jakarta.ws.rs.POST;
 import jakarta.ws.rs.Path;
+import jakarta.ws.rs.Produces;
+import jakarta.ws.rs.core.MediaType;
 import org.jboss.resteasy.reactive.RestPath;
 
 @Path("/api/beta/diagnostics/targets/{targetId}")
@@ -41,4 +51,91 @@ public void gc(@RestPath long targetId) {
                         conn.invokeMBeanOperation(
                                 "java.lang:type=Memory", "gc", null, null, Void.class));
     }
+
+    @Path("/threads")
+    @RolesAllowed("write")
+    @Blocking
+    @Produces({MediaType.APPLICATION_JSON, MediaType.TEXT_PLAIN})
+    @GET
+    public ThreadDump dumpThreads(@RestPath long targetId) {
+        return targetConnectionManager.executeConnectedTask(
+                Target.getTargetById(targetId),
+                conn -> {
+                    CompositeData[] cd =
+                            conn.invokeMBeanOperation(
+                                    "java.lang:type=Threading",
+                                    "dumpAllThreads",
+                                    new Object[] {true, true},
+                                    new String[] {boolean.class.getName(), boolean.class.getName()},
+                                    CompositeData[].class);
+                    return new ThreadDump(List.of(cd).stream().map(ThreadInfo::from).toList());
+                });
+    }
+
+    static record ThreadDump(@JsonValue List<ThreadInfo> threadInfos) {
+        ThreadDump(List<ThreadInfo> threadInfos) {
+            this.threadInfos = new ArrayList<>(threadInfos);
+        }
+
+        // FIXME this should return the same text format as jcmd/jstack commands do, ie match the
+        // HotSpotDiagnosticMXBean dumpThreads operation.
+        // 2024-09-10 12:36:07
+        // Full thread dump OpenJDK 64-Bit Server VM (17.0.12+7 mixed mode, sharing):
+
+        // Threads class SMR info:
+        // _java_thread_list=0x00007fb9400018a0, length=15, elements={
+        // 0x00007fba080278e0, 0x00007fba082158c0, 0x00007fba08216cb0, 0x00007fba0821c1d0,
+        // 0x00007fba0821d600, 0x00007fba0821ea20, 0x00007fba082203c0, 0x00007fba08221900,
+        // 0x00007fba08222d80, 0x00007fba0822a4d0, 0x00007fba0822e3d0, 0x00007fba0832b470,
+        // 0x00007fba08409550, 0x00007fba08630d50, 0x00007fb940000eb0
+        // }
+
+        // "main" #1 prio=5 os_prio=0 cpu=395.16ms elapsed=4884.90s allocated=50569K
+        // defined_classes=2034 tid=0x00007fba080278e0 nid=0x391297 in Object.wait()
+        // [0x00007fba0e5fe000]
+        //    java.lang.Thread.State: WAITING (on object monitor)
+        // 	at java.lang.Object.wait([email protected]/Native Method)
+        // 	- waiting on <0x000000045d468440> (a java.lang.ProcessImpl)
+        // 	at java.lang.Object.wait([email protected]/Object.java:338)
+        // 	at java.lang.ProcessImpl.waitFor([email protected]/ProcessImpl.java:434)
+        // 	- locked <0x000000045d468440> (a java.lang.ProcessImpl)
+        // 	at io.quarkus.cli.build.ExecuteUtil.executeProcess(ExecuteUtil.java:73)
+        // 	at io.quarkus.cli.build.BuildSystemRunner.run(BuildSystemRunner.java:50)
+        // 	at io.quarkus.cli.Dev.call(Dev.java:46)
+        // 	at io.quarkus.cli.Dev.call(Dev.java:18)
+        // 	at picocli.CommandLine.executeUserObject(CommandLine.java:2045)
+        // 	at picocli.CommandLine.access$1500(CommandLine.java:148)
+        // 	at
+        // picocli.CommandLine$RunLast.executeUserObjectOfLastSubcommandWithSameParent(CommandLine.java:2465)
+        // 	at picocli.CommandLine$RunLast.handle(CommandLine.java:2457)
+        // 	at picocli.CommandLine$RunLast.handle(CommandLine.java:2419)
+        // 	at picocli.CommandLine$AbstractParseResultHandler.execute(CommandLine.java:2277)
+        // 	at picocli.CommandLine$RunLast.execute(CommandLine.java:2421)
+        // 	at picocli.CommandLine.execute(CommandLine.java:2174)
+        // 	at io.quarkus.cli.QuarkusCli.run(QuarkusCli.java:116)
+        // 	at
+        // io.quarkus.runtime.ApplicationLifecycleManager.run(ApplicationLifecycleManager.java:140)
+        // 	at io.quarkus.runtime.Quarkus.run(Quarkus.java:71)
+        // 	at io.quarkus.runtime.Quarkus.run(Quarkus.java:44)
+        // 	at io.quarkus.cli.Main.main(Main.java:9)
+
+        //    Locked ownable synchronizers:
+        // 	- None
+        //
+        // 	... (trimmed) ...
+        //
+        // 	"G1 Service" os_prio=0 cpu=256.32ms elapsed=4884.90s tid=0x00007fba081ddbf0 nid=0x39129c
+        // runnable
+
+        // "VM Periodic Task Thread" os_prio=0 cpu=743.47ms elapsed=4884.89s tid=0x00007fba0822be20
+        // nid=0x3912a7 waiting on condition
+
+        // JNI global refs: 24, weak refs: 0
+        @Override
+        public String toString() {
+            var sb = new StringBuilder();
+            this.threadInfos.forEach(sb::append);
+            return sb.toString();
+        }
+    }
 }