skeleton of JFR profiler

agent/src/main/java/io/pyroscope/javaagent/JFRProfilerDelegate.java

@@ -0,0 +1,144 @@
+package io.pyroscope.javaagent;
+
+import io.pyroscope.http.Format;
+import io.pyroscope.javaagent.config.Config;
+import io.pyroscope.labels.Pyroscope;
+import io.pyroscope.labels.io.pyroscope.PyroscopeAsyncProfiler;
+import one.profiler.AsyncProfiler;
+import one.profiler.Counter;
+
+import java.io.DataInputStream;
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.IOException;
+import java.nio.charset.StandardCharsets;
+import java.time.Duration;
+import java.time.Instant;
+
+
+public final class JFRProfilerDelegate implements ProfilerDelegate {
+    private Config config;
+    private EventType eventType;
+    private String alloc;
+    private String lock;
+    private Duration interval;
+    private Format format;
+    private File tempJFRFile;
+
+    private final AsyncProfiler instance = PyroscopeAsyncProfiler.getAsyncProfiler();
+
+    JFRProfilerDelegate(Config config) {
+        setConfig(config);
+    }
+
+    public void setConfig(final Config config) {
+        this.config = config;
+        this.alloc = config.profilingAlloc;
+        this.lock = config.profilingLock;
+        this.eventType = config.profilingEvent;
+        this.interval = config.profilingInterval;
+        this.format = config.format;
+
+        if (format == Format.JFR) {
+            try {
+                // flight recorder is built on top of a file descriptor, so we need a file.
+                tempJFRFile = File.createTempFile("pyroscope", ".jfr");
+                tempJFRFile.deleteOnExit();
+            } catch (IOException e) {
+                throw new IllegalStateException(e);
+            }
+        } else {
+            tempJFRFile = null;
+        }
+    }
+
+    /**
+     * Start async-profiler
+     */
+    public synchronized void start() {
+        if (format == Format.JFR) {
+            try {
+                instance.execute(createJFRCommand());
+            } catch (IOException e) {
+                throw new IllegalStateException(e);
+            }
+        } else {
+            instance.start(eventType.id, interval.toNanos());
+        }
+    }
+
+    /**
+     * Stop async-profiler
+     */
+    public synchronized void stop() {
+        instance.stop();
+    }
+
+    /**
+     *
+     * @param started - time when profiling has been started
+     * @param ended - time when profiling has ended
+     * @return Profiling data and dynamic labels as {@link Snapshot}
+     */
+    public synchronized Snapshot dumpProfile(Instant started, Instant ended) {
+        return dumpImpl(started, ended);
+    }
+
+
+
+    private String createJFRCommand() {
+        StringBuilder sb = new StringBuilder();
+        sb.append("start,event=").append(eventType.id);
+        if (alloc != null && !alloc.isEmpty()) {
+            sb.append(",alloc=").append(alloc);
+            if (config.allocLive) {
+                sb.append(",live");
+            }
+        }
+        if (lock != null && !lock.isEmpty()) {
+            sb.append(",lock=").append(lock);
+        }
+        sb.append(",interval=").append(interval.toNanos())
+            .append(",file=").append(tempJFRFile.toString());
+        if (config.APLogLevel != null) {
+            sb.append(",loglevel=").append(config.APLogLevel);
+        }
+        sb.append(",jstackdepth=").append(config.javaStackDepthMax);
+        if (config.APExtraArguments != null) {
+            sb.append(",").append(config.APExtraArguments);
+        }
+        return sb.toString();
+    }
+
+    private Snapshot dumpImpl(Instant started, Instant ended) {
+        if (config.gcBeforeDump) {
+            System.gc();
+        }
+        final byte[] data;
+        if (format == Format.JFR) {
+            data = dumpJFR();
+        } else {
+            data = instance.dumpCollapsed(Counter.SAMPLES).getBytes(StandardCharsets.UTF_8);
+        }
+        return new Snapshot(
+            format,
+            eventType,
+            started,
+            ended,
+            data,
+            Pyroscope.LabelsWrapper.dump()
+        );
+    }
+
+    private byte[] dumpJFR() {
+        try {
+            byte[] bytes = new byte[(int) tempJFRFile.length()];
+            try (DataInputStream ds = new DataInputStream(new FileInputStream(tempJFRFile))) {
+                ds.readFully(bytes);
+            }
+            return bytes;
+        } catch (IOException e) {
+            throw new IllegalStateException(e);
+        }
+    }
+}