Add heap information setter to the CrashManager interface

Summary: Add a function to the CrashManager interface so clients can get updated information about the current heap being used by the engine.

Reviewed By: davedets

Differential Revision: D16574877

fbshipit-source-id: 4484946f59c116afa70e6fc7881719149d2e85f1

include/hermes/VM/GCBase.h

@@ -435,6 +435,9 @@ class GCBase {
   /// Same as \c getHeapInfo, and it adds the amount of malloc memory in use.
   virtual void getHeapInfoWithMallocSize(HeapInfo &info) = 0;
 
+  /// Populate \p info with crash manager information about the heap
+  virtual void getCrashManagerHeapInfo(CrashManager::HeapInformation &info) = 0;
+
 #ifndef NDEBUG
   /// Populate \p info with more detailed information about the heap that is
   /// too expensive to know during production builds.

include/hermes/VM/GenGCNC.h

@@ -303,6 +303,9 @@ class GenGC final : public GCBase {
   void getHeapInfo(HeapInfo &info) override;
   void getHeapInfoWithMallocSize(HeapInfo &info) override;
 
+  /// Populate \p info with crash manager information about the heap
+  void getCrashManagerHeapInfo(CrashManager::HeapInformation &info) override;
+
 #ifndef NDEBUG
   void getDebugHeapInfo(DebugHeapInfo &info) override;
 #endif

include/hermes/VM/MallocGC.h

@@ -233,6 +233,7 @@ class MallocGC final : public GCBase {
 
   void getHeapInfo(HeapInfo &info) override;
   void getHeapInfoWithMallocSize(HeapInfo &info) override;
+  void getCrashManagerHeapInfo(CrashManager::HeapInformation &info) override;
 
   /// @name Weak references
   /// @{

lib/VM/gcs/GenGCNC.cpp

@@ -915,6 +915,10 @@ void GenGC::updateHeapSize() {
     // size().
     shrinkTo(usedToDesiredSize(static_cast<gcheapsize_t>(weightedUsed_)));
   }
+
+  CrashManager::HeapInformation info;
+  getCrashManagerHeapInfo(info);
+  crashMgr_->setHeapInfo(info);
 }
 
 void GenGC::forAllObjs(const std::function<void(GCCell *)> &callback) {
@@ -1058,6 +1062,11 @@ void GenGC::getHeapInfo(HeapInfo &info) {
   info.youngGenStats = youngGenCollectionCumStats_;
 }
 
+void GenGC::getCrashManagerHeapInfo(CrashManager::HeapInformation &info) {
+  info.size_ = size();
+  info.used_ = used();
+}
+
 void GenGC::getHeapInfoWithMallocSize(HeapInfo &info) {
   getHeapInfo(info);
   // In case the info is being re-used, ensure the count starts at 0.

lib/VM/gcs/MallocGC.cpp

@@ -382,6 +382,12 @@ void MallocGC::getHeapInfoWithMallocSize(HeapInfo &info) {
   }
 }
 
+void MallocGC::getCrashManagerHeapInfo(CrashManager::HeapInformation &info) {
+  info.used_ = allocatedBytes_;
+  // MallocGC does not have a heap size.
+  info.size_ = 0;
+}
+
 #ifndef NDEBUG
 size_t MallocGC::countUsedWeakRefs() const {
   size_t count = 0;

lib/VM/gcs/YoungGenNC.cpp

@@ -419,6 +419,10 @@ void YoungGen::collect() {
   /// TODO(T48709128): remove these when the problem is diagnosed.
   nextGen_->summarizeCardTableBoundaries();
 #endif
+
+  CrashManager::HeapInformation crashHeapInfo;
+  gc_->getCrashManagerHeapInfo(crashHeapInfo);
+  gc_->crashMgr_->setHeapInfo(crashHeapInfo);
 }
 
 void YoungGen::creditExternalMemory(uint32_t size) {

public/hermes/Public/CrashManager.h

@@ -54,6 +54,19 @@ class CrashManager {
   /// CrashManager during a crash.
   virtual void unregisterCallback(CallbackKey key) = 0;
 
+  /// the heap information.
+  struct HeapInformation {
+    /// The amount of memory that is currently in use
+    size_t used_{0};
+    /// The amount of memory that can currently be allocated
+    ///   before a full GC is triggered.
+    size_t size_{0};
+  };
+
+  /// Record the heap information.
+  /// \param heapInfo The current heap information
+  virtual void setHeapInfo(const HeapInformation &heapInfo) = 0;
+
   virtual ~CrashManager() {}
 };
 
@@ -67,6 +80,8 @@ class NopCrashManager final : public CrashManager {
     return 0;
   }
   void unregisterCallback(CallbackKey /*key*/) override {}
+  void setHeapInfo(const HeapInformation & /*heapInfo*/) override {}
+
   ~NopCrashManager() {}
 };