[bun:jsc] Add `generateHeapSnapshotForDebugging`

1 files changed, 28 insertions, 1 deletions

diff --git a/src/bun.js/bindings/BunJSCModule.cpp b/src/bun.js/bindings/BunJSCModule.cpp
index dd5c4b062..3b5995fa0 100644
--- a/src/bun.js/bindings/BunJSCModule.cpp
+++ b/src/bun.js/bindings/BunJSCModule.cpp
@@ -20,6 +20,11 @@
 #include "JavaScriptCore/Completion.h"
 #include "JavaScriptCore/Error.h"
 #include "JavaScriptCore/ErrorInstance.h"
+#include "JavaScriptCore/HeapSnapshotBuilder.h"
+#include "JavaScriptCore/JSONObject.h"
+#include "JavaScriptCore/DeferTermination.h"
+#include "JavaScriptCore/VMTrapsInlines.h"
+
 #include "mimalloc.h"
 
 using namespace JSC;
@@ -339,6 +344,27 @@ JSC_DEFINE_HOST_FUNCTION(functionDrainMicrotasks, (JSGlobalObject * globalObject
     return JSValue::encode(jsUndefined());
 }
 
+JSC_DECLARE_HOST_FUNCTION(functionGenerateHeapSnapshotForDebugging);
+JSC_DEFINE_HOST_FUNCTION(functionGenerateHeapSnapshotForDebugging, (JSGlobalObject * globalObject, CallFrame*))
+{
+    VM& vm = globalObject->vm();
+    JSLockHolder lock(vm);
+    DeferTermination deferScope(vm);
+    auto scope = DECLARE_THROW_SCOPE(vm);
+    String jsonString;
+    {
+        DeferGCForAWhile deferGC(vm); // Prevent concurrent GC from interfering with the full GC that the snapshot does.
+
+        HeapSnapshotBuilder snapshotBuilder(vm.ensureHeapProfiler(), HeapSnapshotBuilder::SnapshotType::GCDebuggingSnapshot);
+        snapshotBuilder.buildSnapshot();
+
+        jsonString = snapshotBuilder.json();
+    }
+    scope.releaseAssertNoException();
+
+    return JSValue::encode(JSONParse(globalObject, WTFMove(jsonString)));
+}
+
 JSC::JSObject* createJSCModule(JSC::JSGlobalObject* globalObject)
 {
     VM& vm = globalObject->vm();
@@ -346,7 +372,7 @@ JSC::JSObject* createJSCModule(JSC::JSGlobalObject* globalObject)
 
     {
         JSC::ObjectInitializationScope initializationScope(vm);
-        object = JSC::constructEmptyObject(globalObject, globalObject->objectPrototype(), 22);
+        object = JSC::constructEmptyObject(globalObject, globalObject->objectPrototype(), 23);
         object->putDirectNativeFunction(vm, globalObject, JSC::Identifier::fromString(vm, "callerSourceOrigin"_s), 1, functionCallerSourceOrigin, NoIntrinsic, JSC::PropertyAttribute::ReadOnly | JSC::PropertyAttribute::DontDelete | 0);
         object->putDirectNativeFunction(vm, globalObject, JSC::Identifier::fromString(vm, "describe"_s), 1, functionDescribe, NoIntrinsic, JSC::PropertyAttribute::ReadOnly | JSC::PropertyAttribute::DontDelete | 0);
         object->putDirectNativeFunction(vm, globalObject, JSC::Identifier::fromString(vm, "describeArray"_s), 1, functionDescribeArray, NoIntrinsic, JSC::PropertyAttribute::ReadOnly | JSC::PropertyAttribute::DontDelete | 0);
@@ -369,6 +395,7 @@ JSC::JSObject* createJSCModule(JSC::JSGlobalObject* globalObject)
         object->putDirectNativeFunction(vm, globalObject, JSC::Identifier::fromString(vm, "startRemoteDebugger"_s), 2, functionStartRemoteDebugger, NoIntrinsic, JSC::PropertyAttribute::ReadOnly | JSC::PropertyAttribute::DontDelete | 0);
         object->putDirectNativeFunction(vm, globalObject, JSC::Identifier::fromString(vm, "totalCompileTime"_s), 1, functionTotalCompileTime, NoIntrinsic, JSC::PropertyAttribute::ReadOnly | JSC::PropertyAttribute::DontDelete | 0);
         object->putDirectNativeFunction(vm, globalObject, JSC::Identifier::fromString(vm, "getProtectedObjects"_s), 1, functionGetProtectedObjects, NoIntrinsic, JSC::PropertyAttribute::ReadOnly | JSC::PropertyAttribute::DontDelete | 0);
+        object->putDirectNativeFunction(vm, globalObject, JSC::Identifier::fromString(vm, "generateHeapSnapshotForDebugging"_s), 0, functionGenerateHeapSnapshotForDebugging, NoIntrinsic, JSC::PropertyAttribute::ReadOnly | JSC::PropertyAttribute::DontDelete | 0);
     }
 
     return object;