Improve startup time (#1667)

Author: trask

agent/agent-bootstrap/src/main/java/com/microsoft/applicationinsights/agent/bootstrap/BytecodeUtil.java

@@ -29,10 +29,7 @@
 import io.opentelemetry.instrumentation.api.aisdk.MicrometerUtil;
 import io.opentelemetry.instrumentation.api.aisdk.MicrometerUtil.MicrometerUtilDelegate;
 
-import static java.util.concurrent.TimeUnit.DAYS;
-import static java.util.concurrent.TimeUnit.HOURS;
-import static java.util.concurrent.TimeUnit.MINUTES;
-import static java.util.concurrent.TimeUnit.SECONDS;
+import static java.util.concurrent.TimeUnit.*;
 
 // supporting all properties of event, metric, remote dependency and page view telemetry
 public class BytecodeUtil {
@@ -146,6 +143,28 @@ public static void copy(Map<String, String> source, Map<String, String> target,
         }
     }
 
+    // this exists only to support -Dapplicationinsights.debug.signedJarAccess=true
+    private static final ThreadLocal<Long> startNanosHolder = new ThreadLocal<>();
+
+    public static void onEnter() {
+        startNanosHolder.set(System.nanoTime());
+    }
+
+    public static void onExit() {
+        Long startNanos = startNanosHolder.get();
+        if (startNanos == null) {
+            System.out.println("Signed jar access (no timing available)");
+            Thread.dumpStack();
+        } else {
+            long durationNanos = System.nanoTime() - startNanos;
+            if (durationNanos > MILLISECONDS.toNanos(1)) {
+                System.out.println("Signed jar access (" + NANOSECONDS.toMillis(durationNanos) + " milliseconds)");
+                Thread.dumpStack();
+            }
+        }
+        startNanosHolder.remove();
+    }
+
     public interface BytecodeUtilDelegate {
 
         void trackEvent(String name, Map<String, String> properties, Map<String, String> tags, Map<String, Double> metrics,

agent/agent-bootstrap/src/main/java/com/microsoft/applicationinsights/agent/bootstrap/diagnostics/SdkVersionFinder.java

@@ -2,36 +2,48 @@
 
 import java.io.IOException;
 import java.io.InputStream;
+import java.nio.file.Path;
 import java.util.Properties;
+import java.util.jar.JarEntry;
+import java.util.jar.JarFile;
 
 public class SdkVersionFinder extends CachedDiagnosticsValueFinder {
 
+    private static volatile String value;
+
     @Override
     public String getName() {
         return "sdkVersion";
     }
 
     @Override
     protected String populateValue() {
-        return readVersion();
+        return value;
+    }
+
+    public static String getTheValue() {
+        return value;
+    }
+
+    public static String initVersion(Path agentPath) {
+        value = readVersion(agentPath);
+        return value;
     }
 
-    public static String readVersion() {
-        Properties props = new Properties();
-        InputStream in = ClassLoader.getSystemClassLoader().getResourceAsStream("ai.sdk-version.properties");
-        if (in != null) {
-            try {
-                props.load(in);
-            } catch (IOException e) {
-                e.printStackTrace();
-            } finally {
-                try {
-                    in.close();
-                } catch (IOException e) {
-                    e.printStackTrace();
+    private static String readVersion(Path agentPath) {
+        try {
+            // reading from file instead of from classpath, in order to avoid triggering jar file signature verification
+            try (JarFile jarFile = new JarFile(agentPath.toFile(), false)) {
+                JarEntry entry = jarFile.getJarEntry("ai.sdk-version.properties");
+                try (InputStream in = jarFile.getInputStream(entry)) {
+                    Properties props = new Properties();
+                    props.load(in);
+                    return props.getProperty("version");
                 }
             }
+        } catch (IOException e) {
+            e.printStackTrace();
         }
-        return props.getProperty("version");
+        return "unknown";
     }
 }