Add HeapProfiler.collectGarbage implementation

Summary:
In Chrome, there's a garbage can icon in the memory profiler page that you can
click to force a garbage collection.
Hermes was previously not responding to that button. Add support for this inspector
message type.

The collection it starts is fully synchronous and will block JS from running. It typically
completes quite fast for small heaps, and about 1 second for heaps over 100 MB big.

Changelog:
[Internal][Added] Add support for garbage collection during heap profiling with Hermes

Reviewed By: neildhar

Differential Revision: D24349262

fbshipit-source-id: fe62b8df4d2b67ab3930e5d57f94478b2a88a549

ReactCommon/hermes/inspector/chrome/Connection.cpp

@@ -93,6 +93,7 @@ class Connection::Impl : public inspector::InspectorObserver,
       const m::heapProfiler::StartTrackingHeapObjectsRequest &req) override;
   void handle(
       const m::heapProfiler::StopTrackingHeapObjectsRequest &req) override;
+  void handle(const m::heapProfiler::CollectGarbageRequest &req) override;
   void handle(const m::runtime::EvaluateRequest &req) override;
   void handle(const m::runtime::GetPropertiesRequest &req) override;
   void handle(const m::runtime::RunIfWaitingForDebuggerRequest &req) override;
@@ -579,6 +580,22 @@ void Connection::Impl::handle(
       /* stopStackTraceCapture */ true);
 }
 
+void Connection::Impl::handle(
+    const m::heapProfiler::CollectGarbageRequest &req) {
+  const auto id = req.id;
+
+  inspector_
+      ->executeIfEnabled(
+          "HeapProfiler.collectGarbage",
+          [this](const debugger::ProgramState &) {
+            getRuntime().instrumentation().collectGarbage("inspector");
+          })
+      .via(executor_.get())
+      .thenValue(
+          [this, id](auto &&) { sendResponseToClient(m::makeOkResponse(id)); })
+      .thenError<std::exception>(sendErrorToClient(req.id));
+}
+
 void Connection::Impl::handle(const m::runtime::EvaluateRequest &req) {
   auto remoteObjPtr = std::make_shared<m::runtime::RemoteObject>();
 

ReactCommon/hermes/inspector/chrome/MessageTypes.cpp

@@ -1,5 +1,5 @@
 // Copyright 2004-present Facebook. All Rights Reserved.
-// @generated SignedSource<<80b4da5580a1fe18b9551723bdf7cab0>>
+// @generated SignedSource<<e4c911229f0e8cac24dbc3ec8a933d5e>>
 
 #include "MessageTypes.h"
 
@@ -44,6 +44,8 @@ std::unique_ptr<Request> Request::fromJsonThrowOnError(const std::string &str) {
       {"Debugger.stepInto", makeUnique<debugger::StepIntoRequest>},
       {"Debugger.stepOut", makeUnique<debugger::StepOutRequest>},
       {"Debugger.stepOver", makeUnique<debugger::StepOverRequest>},
+      {"HeapProfiler.collectGarbage",
+       makeUnique<heapProfiler::CollectGarbageRequest>},
       {"HeapProfiler.startTrackingHeapObjects",
        makeUnique<heapProfiler::StartTrackingHeapObjectsRequest>},
       {"HeapProfiler.stopTrackingHeapObjects",
@@ -656,6 +658,27 @@ void debugger::StepOverRequest::accept(RequestHandler &handler) const {
   handler.handle(*this);
 }
 
+heapProfiler::CollectGarbageRequest::CollectGarbageRequest()
+    : Request("HeapProfiler.collectGarbage") {}
+
+heapProfiler::CollectGarbageRequest::CollectGarbageRequest(const dynamic &obj)
+    : Request("HeapProfiler.collectGarbage") {
+  assign(id, obj, "id");
+  assign(method, obj, "method");
+}
+
+dynamic heapProfiler::CollectGarbageRequest::toDynamic() const {
+  dynamic obj = dynamic::object;
+  put(obj, "id", id);
+  put(obj, "method", method);
+  return obj;
+}
+
+void heapProfiler::CollectGarbageRequest::accept(
+    RequestHandler &handler) const {
+  handler.handle(*this);
+}
+
 heapProfiler::StartTrackingHeapObjectsRequest::StartTrackingHeapObjectsRequest()
     : Request("HeapProfiler.startTrackingHeapObjects") {}
 

ReactCommon/hermes/inspector/chrome/MessageTypes.h

@@ -1,5 +1,5 @@
 // Copyright 2004-present Facebook. All Rights Reserved.
-// @generated SignedSource<<7383ffe2d956ba3aef8262dbee2f3427>>
+// @generated SignedSource<<e3e5526b8e266b560b9dc9e42cc0d6c5>>
 
 #pragma once
 
@@ -71,6 +71,7 @@ using UnserializableValue = std::string;
 
 namespace heapProfiler {
 struct AddHeapSnapshotChunkNotification;
+struct CollectGarbageRequest;
 struct HeapStatsUpdateNotification;
 struct LastSeenObjectIdNotification;
 struct ReportHeapSnapshotProgressNotification;
@@ -99,6 +100,7 @@ struct RequestHandler {
   virtual void handle(const debugger::StepIntoRequest &req) = 0;
   virtual void handle(const debugger::StepOutRequest &req) = 0;
   virtual void handle(const debugger::StepOverRequest &req) = 0;
+  virtual void handle(const heapProfiler::CollectGarbageRequest &req) = 0;
   virtual void handle(
       const heapProfiler::StartTrackingHeapObjectsRequest &req) = 0;
   virtual void handle(
@@ -127,6 +129,7 @@ struct NoopRequestHandler : public RequestHandler {
   void handle(const debugger::StepIntoRequest &req) override {}
   void handle(const debugger::StepOutRequest &req) override {}
   void handle(const debugger::StepOverRequest &req) override {}
+  void handle(const heapProfiler::CollectGarbageRequest &req) override {}
   void handle(
       const heapProfiler::StartTrackingHeapObjectsRequest &req) override {}
   void handle(
@@ -413,6 +416,14 @@ struct debugger::StepOverRequest : public Request {
   void accept(RequestHandler &handler) const override;
 };
 
+struct heapProfiler::CollectGarbageRequest : public Request {
+  CollectGarbageRequest();
+  explicit CollectGarbageRequest(const folly::dynamic &obj);
+
+  folly::dynamic toDynamic() const override;
+  void accept(RequestHandler &handler) const override;
+};
+
 struct heapProfiler::StartTrackingHeapObjectsRequest : public Request {
   StartTrackingHeapObjectsRequest();
   explicit StartTrackingHeapObjectsRequest(const folly::dynamic &obj);

ReactCommon/hermes/inspector/tools/message_types.txt

@@ -17,6 +17,7 @@ Debugger.stepInto
 Debugger.stepOut
 Debugger.stepOver
 HeapProfiler.addHeapSnapshotChunk
+HeapProfiler.collectGarbage
 HeapProfiler.reportHeapSnapshotProgress
 HeapProfiler.takeHeapSnapshot
 HeapProfiler.startTrackingHeapObjects