Move JSON generation to sender thread to improve startup time.

Author: AlexeyKuznetsov-DD

dd-java-agent/src/main/java/datadog/trace/bootstrap/BootstrapInitializationTelemetry.java

@@ -6,7 +6,7 @@
 import java.io.Closeable;
 import java.io.OutputStream;
 import java.util.ArrayList;
-import java.util.Collections;
+import java.util.Arrays;
 import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Map;
@@ -51,14 +51,14 @@ public static BootstrapInitializationTelemetry createFromForwarderPath(String fo
    */
   public abstract void onError(Throwable t);
 
+  public abstract void onError(String reasonCode);
+
   /**
    * Indicates an exception that occurred during the bootstrapping process that left initialization
    * incomplete. Equivalent to calling {@link #onError(Throwable)} and {@link #markIncomplete()}
    */
   public abstract void onFatalError(Throwable t);
 
-  public abstract void onError(String reasonCode);
-
   public abstract void markIncomplete();
 
   public abstract void finish();
@@ -78,10 +78,10 @@ public void onAbort(String reasonCode) {}
     public void onError(String reasonCode) {}
 
     @Override
-    public void onFatalError(Throwable t) {}
+    public void onError(Throwable t) {}
 
     @Override
-    public void onError(Throwable t) {}
+    public void onFatalError(Throwable t) {}
 
     @Override
     public void markIncomplete() {}
@@ -93,24 +93,24 @@ public void finish() {}
   public static final class JsonBased extends BootstrapInitializationTelemetry {
     private final JsonSender sender;
 
-    private final List<String> meta;
+    private final Map<String, String> meta;
     private final Map<String, List<String>> points;
 
     // one way false to true
     private volatile boolean incomplete = false;
-    private volatile boolean error = false;
 
     JsonBased(JsonSender sender) {
       this.sender = sender;
-      this.meta = new ArrayList<>();
+      this.meta = new LinkedHashMap<>();
       this.points = new LinkedHashMap<>();
+
+      setMetaInfo("success", "success", "Successfully configured ddtrace package");
     }
 
     @Override
     public void initMetaInfo(String attr, String value) {
       synchronized (this.meta) {
-        this.meta.add(attr);
-        this.meta.add(value);
+        this.meta.put(attr, value);
       }
     }
 
@@ -123,7 +123,6 @@ public void onAbort(String reasonCode) {
 
     @Override
     public void onError(Throwable t) {
-      error = true;
       setMetaInfo("error", "internal_error", t.getMessage());
 
       List<String> causes = new ArrayList<>();
@@ -142,7 +141,13 @@ public void onError(Throwable t) {
         causes = causes.subList(numCauses - maxTags, numCauses);
       }
 
-      onPoint("library_entrypoint.error", causes);
+      onPoint("library_entrypoint.error", causes.toArray(new String[0]));
+    }
+
+    @Override
+    public void onError(String reasonCode) {
+      onPoint("library_entrypoint.error", "error_type:" + reasonCode);
+      setMetaInfo("error", mapResultClass(reasonCode), reasonCode);
     }
 
     private int maxTags() {
@@ -165,13 +170,6 @@ public void onFatalError(Throwable t) {
       markIncomplete();
     }
 
-    @Override
-    public void onError(String reasonCode) {
-      error = true;
-      onPoint("library_entrypoint.error", "error_type:" + reasonCode);
-      setMetaInfo("error", mapResultClass(reasonCode), reasonCode);
-    }
-
     private void setMetaInfo(String result, String resultClass, String resultReason) {
       initMetaInfo("result", result);
       initMetaInfo("result_class", resultClass);
@@ -195,13 +193,9 @@ private String mapResultClass(String reasonCode) {
       }
     }
 
-    private void onPoint(String name, String tag) {
-      onPoint(name, Collections.singletonList(tag));
-    }
-
-    private void onPoint(String name, List<String> tags) {
+    private void onPoint(String name, String... tags) {
       synchronized (this.points) {
-        this.points.put(name, tags);
+        this.points.put(name, Arrays.asList(tags));
       }
     }
 
@@ -212,51 +206,16 @@ public void markIncomplete() {
 
     @Override
     public void finish() {
-      if (!this.incomplete && !this.error) {
-        setMetaInfo("success", "success", "Successfully configured ddtrace package");
+      if (!this.incomplete) {
+        onPoint("library_entrypoint.complete");
       }
 
-      try (JsonWriter writer = new JsonWriter()) {
-        writer.beginObject();
-        writer.name("metadata").beginObject();
-        synchronized (this.meta) {
-          for (int i = 0; i + 1 < this.meta.size(); i = i + 2) {
-            writer.name(this.meta.get(i));
-            writer.value(this.meta.get(i + 1));
-          }
-        }
-        writer.endObject();
-
-        writer.name("points").beginArray();
-        synchronized (this.points) {
-          for (Map.Entry<String, List<String>> entry : points.entrySet()) {
-            writer.beginObject();
-            writer.name("name").value(entry.getKey());
-            writer.name("tags").beginArray();
-            for (String tag : entry.getValue()) {
-              writer.value(tag);
-            }
-            writer.endArray();
-            writer.endObject();
-          }
-          this.points.clear();
-        }
-        if (!this.incomplete) {
-          writer.beginObject().name("name").value("library_entrypoint.complete").endObject();
-        }
-        writer.endArray();
-        writer.endObject();
-
-        this.sender.send(writer.toByteArray());
-      } catch (Throwable t) {
-        // Since this is the reporting mechanism, there's little recourse here
-        // Decided to simply ignore - arguably might want to write to stderr
-      }
+      this.sender.send(meta, points);
     }
   }
 
   public interface JsonSender {
-    void send(byte[] payload);
+    void send(Map<String, String> meta, Map<String, List<String>> points);
   }
 
   public static final class ForwarderJsonSender implements JsonSender {
@@ -267,21 +226,24 @@ public static final class ForwarderJsonSender implements JsonSender {
     }
 
     @Override
-    public void send(byte[] payload) {
-      ForwarderJsonSenderThread t = new ForwarderJsonSenderThread(forwarderPath, payload);
+    public void send(Map<String, String> meta, Map<String, List<String>> points) {
+      ForwarderJsonSenderThread t = new ForwarderJsonSenderThread(forwarderPath, meta, points);
       t.setDaemon(true);
       t.start();
     }
   }
 
   public static final class ForwarderJsonSenderThread extends Thread {
     private final String forwarderPath;
-    private final byte[] payload;
+    private final Map<String, String> meta;
+    private final Map<String, List<String>> points;
 
-    public ForwarderJsonSenderThread(String forwarderPath, byte[] payload) {
+    public ForwarderJsonSenderThread(
+        String forwarderPath, Map<String, String> meta, Map<String, List<String>> points) {
       super("dd-forwarder-json-sender");
       this.forwarderPath = forwarderPath;
-      this.payload = payload;
+      this.meta = meta;
+      this.points = points;
     }
 
     @SuppressForbidden
@@ -291,6 +253,8 @@ public void run() {
 
       // Run forwarder and mute tracing for subprocesses executed in by dd-java-agent.
       try (final Closeable ignored = muteTracing()) {
+        byte[] payload = json();
+
         Process process = builder.start();
         try (OutputStream out = process.getOutputStream()) {
           out.write(payload);
@@ -301,6 +265,39 @@ public void run() {
       }
     }
 
+    private byte[] json() {
+      try (JsonWriter writer = new JsonWriter()) {
+        writer.beginObject();
+        writer.name("metadata").beginObject();
+        synchronized (this.meta) {
+          for (Map.Entry<String, String> entry : meta.entrySet()) {
+            writer.name(entry.getKey());
+            writer.value(entry.getValue());
+          }
+        }
+        writer.endObject();
+
+        writer.name("points").beginArray();
+        synchronized (this.points) {
+          for (Map.Entry<String, List<String>> entry : points.entrySet()) {
+            writer.beginObject();
+            writer.name("name").value(entry.getKey());
+            writer.name("tags").beginArray();
+            for (String tag : entry.getValue()) {
+              writer.value(tag);
+            }
+            writer.endArray();
+            writer.endObject();
+          }
+          this.points.clear();
+        }
+        writer.endArray();
+        writer.endObject();
+
+        return writer.toByteArray();
+      }
+    }
+
     @SuppressForbidden
     private Closeable muteTracing() {
       try {