perf: shorthand for begin/end group event pair

Group-related messages compose a large part of the trace. Which is a 
problem because they carry a lot of useless information and they are 
ultimately removed from the final appmap event list. To solve this 
issue, I created a shorter representation in the frontend which is 
inflated in the backend.

[skip ci]

build/schema/schema.yml

@@ -775,6 +775,22 @@
     - before
     - after
 
+# Shorthand for group event pair to improve performance.
+# Group-related messages are a large part of the trace.
+- $id: group-message
+  type: object
+  additionalProperties: false
+  required: [type, group, child, description]
+  properties:
+    type:
+      const: group
+    group:
+      $ref: group
+    child:
+      $ref: group
+    description:
+      type: string
+
 - $id: event-message
   type: object
   additionalProperties: false
@@ -1147,6 +1163,7 @@
     - $ref: stop-message
     - $ref: error-message
     - $ref: source-message
+    - $ref: group-message
     - $ref: event-message
     - $ref: amend-message
 

components/agent/default/index.mjs

@@ -16,6 +16,7 @@ export default (dependencies) => {
       formatError,
       formatStartTrack,
       formatStopTrack,
+      formatGroup,
       formatBeginEvent,
       formatEndEvent,
       formatBeforeEvent,
@@ -95,6 +96,12 @@ export default (dependencies) => {
     requestRemoteAgentAsync: ({ emitter }, method, path, body) =>
       requestRemoteEmitterAsync(emitter, method, path, body),
     /* c8 ignore stop */
+    recordGroup: ({ emitter, frontend }, child, description) => {
+      sendEmitter(
+        emitter,
+        formatGroup(frontend, getCurrentGroup(), child, description),
+      );
+    },
     recordBeginAmend: generateRecord(formatBeginAmend),
     recordEndAmend: generateRecord(formatEndAmend),
     recordBeforeAmend: generateRecord(formatBeforeAmend),

components/agent/default/index.test.mjs

@@ -21,6 +21,7 @@ const {
   getInstrumentationIdentifier,
   getSerializationEmptyValue,
   getFreshTab,
+  recordGroup,
   recordBeforeEvent,
   recordAfterEvent,
   formatQueryPayload,
@@ -40,6 +41,7 @@ getSerializationEmptyValue(agent);
 
 assertEqual(typeof getInstrumentationIdentifier(agent), "string");
 recordStartTrack(agent, "record", {}, null);
+recordGroup(agent, 123, "description");
 assertEqual(
   evalGlobal(
     instrument(agent, { url: "file:///base/main.js", content: "123;" }),
@@ -62,6 +64,12 @@ assertDeepEqual(takeLocalAgentTrace(agent, "record"), [
     configuration: {},
     url: null,
   },
+  {
+    type: "group",
+    group: 0,
+    child: 123,
+    description: "description",
+  },
   {
     type: "source",
     url: "file:///base/main.js",

components/frontend/default/index.mjs

@@ -73,6 +73,12 @@ export default (dependencies) => {
       message,
       stack,
     }),
+    formatGroup: ({}, group, child, description) => ({
+      type: "group",
+      group,
+      child,
+      description,
+    }),
     formatBeginEvent: generateFormatEvent("begin"),
     formatEndEvent: generateFormatEvent("end"),
     formatBeforeEvent: generateFormatEvent("before"),

components/frontend/default/index.test.mjs

@@ -24,6 +24,7 @@ const {
   instrument,
   getFreshTab,
   getBundlePayload,
+  formatGroup,
   formatBeginEvent,
   formatBeginAmend,
 } = Frontend(dependencies);
@@ -45,6 +46,8 @@ assertEqual(typeof getSerializationEmptyValue(frontend), "symbol");
 
 assertEqual(typeof getFreshTab(frontend), "number");
 
+validateMessage(formatGroup(frontend, 123, 456, "description"));
+
 validateMessage(formatStartTrack(frontend, "track", {}, null));
 
 validateMessage(formatStopTrack(frontend, "track", 0));

components/hook-group/node/index.mjs

@@ -5,13 +5,7 @@ const { Set } = globalThis;
 export default (dependencies) => {
   const {
     util: { assert },
-    agent: {
-      getFreshTab,
-      recordBeginEvent,
-      recordEndEvent,
-      formatGroupPayload,
-      formatUngroupPayload,
-    },
+    agent: { recordGroup },
   } = dependencies;
   return {
     hook: (agent, { ordering }) => {
@@ -23,13 +17,7 @@ export default (dependencies) => {
           init: (id, description, _origin) => {
             assert(!groups.has(id), "duplicate async id");
             groups.add(id);
-            const tab = getFreshTab(agent);
-            recordBeginEvent(
-              agent,
-              tab,
-              formatGroupPayload(agent, id, description),
-            );
-            recordEndEvent(agent, tab, formatUngroupPayload(agent, id));
+            recordGroup(agent, id, description);
           },
         });
         hook.enable();

components/trace/appmap/index.mjs

@@ -44,6 +44,32 @@ export default (dependencies) => {
           errors.push(message);
         } else if (type === "event") {
           events.push(message);
+        } else if (type === "group") {
+          events.push(
+            {
+              type: "event",
+              site: "begin",
+              tab: 0,
+              group: message.group,
+              time: 0,
+              payload: {
+                type: "group",
+                group: message.child,
+                description: message.description,
+              },
+            },
+            {
+              type: "event",
+              site: "end",
+              tab: 0,
+              group: message.group,
+              time: 0,
+              payload: {
+                type: "ungroup",
+                group: message.child,
+              },
+            },
+          );
         } else if (type === "source") {
           sources.push(message);
         } else if (type === "amend") {

components/trace/appmap/index.test.mjs

@@ -86,6 +86,12 @@ assertDeepEqual(
         arguments: [{ type: "string", print: "ARG-PRINT" }],
       },
     },
+    {
+      type: "group",
+      group: 0,
+      child: 1,
+      description: "description",
+    },
     {
       type: "event",
       site: "end",