Delay load v8jsi.dll (#7)

* delay load the dll by default (so that consumers can have a run-time / optional dependency on v8jsi.dll without needing to distribute it if unused);
* the Platform must be process-singleton to match v8 internals (V8 is not embedder-friendly and makes several assumptions about objects that are initialized once per process - we're matching that design with our V8Platform to avoid crashes if multiple contexts are created / shut down during a process' lifetime);

ReactNative.V8Jsi.Windows.targets

@@ -6,6 +6,7 @@
       <AdditionalLibraryDirectories Condition="'$(Configuration)' == 'Debug' And ('$(Platform)' == 'Win32' Or '$(Platform)' == 'x86')">$(MSBuildThisFileDirectory)..\..\lib\Debug\x86;%(AdditionalLibraryDirectories)</AdditionalLibraryDirectories>
       <AdditionalLibraryDirectories Condition="'$(Configuration)' == 'Release' And ('$(Platform)' == 'Win32' Or '$(Platform)' == 'x86')">$(MSBuildThisFileDirectory)..\..\lib\Release\x86;%(AdditionalLibraryDirectories)</AdditionalLibraryDirectories>
       <AdditionalDependencies>v8jsi.dll.lib;%(AdditionalDependencies)</AdditionalDependencies>
+      <DelayLoadDLLs>v8jsi.dll;%(DelayLoadDLLs)</DelayLoadDLLs>
     </Link>
     <ClCompile>
       <AdditionalIncludeDirectories>$(MSBuildThisFileDirectory)include;%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>

config.json

@@ -1,4 +1,4 @@
 {
-    "version": "0.2.2",
+    "version": "0.2.3",
     "v8ref": "refs/branch-heads/8.0"
 }

localbuild.ps1

@@ -3,7 +3,7 @@
 $OutputPath = "$PSScriptRoot\out"
 $SourcesPath = $PSScriptRoot
 $Platforms = "x64", "x86"
-$Configurations = "Release", "Debug", "Release-Clang", "EXPERIMENTAL-libcpp-Clang"
+$Configurations = "Debug", "Release", "Release-Clang", "EXPERIMENTAL-libcpp-Clang"
 
 Write-Host "Downloading environment..."
 & ".\scripts\download_depottools.ps1" -SourcesPath $SourcesPath

src/V8JsiRuntime.cpp

@@ -1128,7 +1128,30 @@ bool V8Runtime::isFunction(const jsi::Object &obj) const {
 
 bool V8Runtime::isHostObject(const jsi::Object &obj) const {
   _ISOLATE_CONTEXT_ENTER
-  std::abort();
+  if (objectRef(obj)->InternalFieldCount() < 1) {
+    return false;
+  }
+
+  auto internalFieldRef = objectRef(obj)->GetInternalField(0);
+  if (internalFieldRef.IsEmpty()) {
+    return false;
+  }
+
+  v8::Local<v8::External> internalField = v8::Local<v8::External>::Cast(internalFieldRef);
+  if (!internalField->Value()) {
+    return false;
+  }
+
+  HostObjectProxy *hostObjectProxy = reinterpret_cast<HostObjectProxy *>(internalField->Value());
+
+  for (const std::shared_ptr<HostObjectLifetimeTracker>& hostObjectLifetimeTracker :
+       host_object_lifetime_tracker_list_) {
+    if (hostObjectLifetimeTracker->IsEqual(hostObjectProxy)) {
+      return true;
+    }
+  }
+
+  return false;
 }
 
 // Very expensive

src/V8JsiRuntime_impl.h

@@ -98,12 +98,14 @@ while (!use_count_s_.compare_exchange_weak(current, current + 1))
   ;*/
 
     if (use_count_s_++ == 0) {
+      if (!platform_s_) {
 #ifdef USE_DEFAULT_PLATFORM
-      platform_s_ = v8::platform::NewDefaultPlatform();
+        platform_s_ = v8::platform::NewDefaultPlatform();
 #else
-      platform_s_ = std::make_unique<V8Platform>(true);
+        platform_s_ = std::make_unique<V8Platform>(true);
 #endif
-      v8::V8::InitializePlatform(platform_s_.get());
+        v8::V8::InitializePlatform(platform_s_.get());
+      }
     }
   }
 
@@ -114,8 +116,10 @@ while (!use_count_s_.compare_exchange_weak(current, current - 1))
   ;*/
 
     if (--use_count_s_ == 0) {
-      v8::V8::ShutdownPlatform();
-      platform_s_ = nullptr;
+      // We cannot shutdown the platform once created because V8 internally references bits of the platform from process-globals
+      // This cannot be worked around, the design of V8 is not currently embedder-friendly
+      //v8::V8::ShutdownPlatform();
+      //platform_s_ = nullptr;
     }
   }
 
@@ -190,6 +194,10 @@ class V8Runtime : public facebook::jsi::Runtime {
       std::cout << "~HostObjectLifetimeTracker" << std::endl;
     }
 
+    bool IsEqual(IHostProxy *hostProxy) const noexcept {
+      return hostProxy_ == hostProxy;
+    }
+
    private:
     v8::Global<v8::Object> objectTracker_;
     std::atomic<bool> isReset_{false};