Move snapshot UUID generation at serialization

UUID generation is not cheap, and therefore should be performed only
when the snapshot is about to be sent.
Moving UUID generation at serialization time makes it out of the
critical path.

.gitlab/benchmarks.yml

@@ -111,7 +111,6 @@ debugger-benchmarks:
           - dd-java-agent/agent-debugger/**/*
         compare_to: "master"
       when: on_success
-    - when: manual
       allow_failure: true
   tags: ["runner:apm-k8s-tweaked-metal"]
   interruptible: true

dd-java-agent/agent-debugger/src/main/java/com/datadog/debugger/sink/Snapshot.java

@@ -34,7 +34,6 @@ public class Snapshot {
   private String exceptionId;
 
   public Snapshot(java.lang.Thread thread, ProbeImplementation probeImplementation, int maxDepth) {
-    this.id = UUID.randomUUID().toString();
     this.version = VERSION;
     this.timestamp = System.currentTimeMillis();
     this.captures = new Captures();
@@ -105,6 +104,10 @@ public void addCaughtExceptions(List<CapturedContext.CapturedThrowable> throwabl
   }
 
   public String getId() {
+    // lazily generates snapshot id
+    if (id == null) {
+      id = UUID.randomUUID().toString();
+    }
     return id;
   }
 

dd-java-agent/agent-debugger/src/main/java/com/datadog/debugger/sink/SnapshotSink.java

@@ -63,6 +63,7 @@ public boolean offer(Snapshot snapshot) {
   }
 
   String serializeSnapshot(String serviceName, Snapshot snapshot) {
+    snapshot.getId(); // Ensure id is generated
     String str = DebuggerAgent.getSnapshotSerializer().serializeSnapshot(serviceName, snapshot);
     String prunedStr = SnapshotPruner.prune(str, MAX_SNAPSHOT_SIZE, 4);
     if (prunedStr.length() != str.length()) {