Only reload libraries when they may have been modified.

runtime/vm/dart_api_impl.cc

Index: runtime/vm/dart_api_impl.cc
diff --git a/runtime/vm/dart_api_impl.cc b/runtime/vm/dart_api_impl.cc
index 34a8d33f97af77b721ac7514d7c0b81924c5279b..83ab446bbc45e5f5fafbe690e8bf9f67f178f4ba 100644
--- a/runtime/vm/dart_api_impl.cc
+++ b/runtime/vm/dart_api_impl.cc
@@ -21,6 +21,7 @@
 #include "vm/flags.h"
 #include "vm/growable_array.h"
 #include "vm/lockers.h"
+#include "vm/isolate_reload.h"
 #include "vm/message.h"
 #include "vm/message_handler.h"
 #include "vm/native_entry.h"
@@ -5221,6 +5222,7 @@ static void CompileSource(Thread* thread,
 
 
 DART_EXPORT Dart_Handle Dart_LoadScript(Dart_Handle url,
+                                        Dart_Handle resolved_url,
                                         Dart_Handle source,
                                         intptr_t line_offset,
                                         intptr_t column_offset) {
@@ -5231,6 +5233,13 @@ DART_EXPORT Dart_Handle Dart_LoadScript(Dart_Handle url,
   if (url_str.IsNull()) {
     RETURN_TYPE_ERROR(Z, url, String);
   }
+  if (Dart_IsNull(resolved_url)) {
+    resolved_url = url;
+  }
+  const String& resolved_url_str = Api::UnwrapStringHandle(Z, resolved_url);
+  if (resolved_url_str.IsNull()) {
+    RETURN_TYPE_ERROR(Z, resolved_url, String);
+  }
   const String& source_str = Api::UnwrapStringHandle(Z, source);
   if (source_str.IsNull()) {
     RETURN_TYPE_ERROR(Z, source, String);
@@ -5259,8 +5268,9 @@ DART_EXPORT Dart_Handle Dart_LoadScript(Dart_Handle url,
   library.Register(T);
   I->object_store()->set_root_library(library);
 
-  const Script& script = Script::Handle(Z,
-      Script::New(url_str, source_str, RawScript::kScriptTag));
+  const Script& script =
+      Script::Handle(Z, Script::New(url_str, resolved_url_str, source_str,
+                                    RawScript::kScriptTag));
   script.SetLocationOffset(line_offset, column_offset);
   Dart_Handle result;
   CompileSource(T, library, script, &result);
@@ -5498,6 +5508,7 @@ DART_EXPORT Dart_Handle Dart_LibraryHandleError(Dart_Handle library_in,
 
 
 DART_EXPORT Dart_Handle Dart_LoadLibrary(Dart_Handle url,
+                                         Dart_Handle resolved_url,
                                          Dart_Handle source,
                                          intptr_t line_offset,
                                          intptr_t column_offset) {
@@ -5508,6 +5519,13 @@ DART_EXPORT Dart_Handle Dart_LoadLibrary(Dart_Handle url,
   if (url_str.IsNull()) {
     RETURN_TYPE_ERROR(Z, url, String);
   }
+  if (Dart_IsNull(resolved_url)) {
+    resolved_url = url;
+  }
+  const String& resolved_url_str = Api::UnwrapStringHandle(Z, resolved_url);
+  if (resolved_url_str.IsNull()) {
+    RETURN_TYPE_ERROR(Z, resolved_url, String);
+  }
   const String& source_str = Api::UnwrapStringHandle(Z, source);
   if (source_str.IsNull()) {
     RETURN_TYPE_ERROR(Z, source, String);
@@ -5537,8 +5555,9 @@ DART_EXPORT Dart_Handle Dart_LoadLibrary(Dart_Handle url,
     return Api::NewError("%s: library '%s' has already been loaded.",
                          CURRENT_FUNC, url_str.ToCString());
   }
-  const Script& script = Script::Handle(Z,
-      Script::New(url_str, source_str, RawScript::kLibraryTag));
+  const Script& script =
+      Script::Handle(Z, Script::New(url_str, resolved_url_str, source_str,
+                                    RawScript::kLibraryTag));
   script.SetLocationOffset(line_offset, column_offset);
   Dart_Handle result;
   CompileSource(T, library, script, &result);
@@ -5604,6 +5623,7 @@ DART_EXPORT Dart_Handle Dart_LibraryImportLibrary(Dart_Handle library,
 
 DART_EXPORT Dart_Handle Dart_LoadSource(Dart_Handle library,
                                         Dart_Handle url,
+                                        Dart_Handle resolved_url,
                                         Dart_Handle source,
                                         intptr_t line_offset,
                                         intptr_t column_offset) {
@@ -5618,6 +5638,13 @@ DART_EXPORT Dart_Handle Dart_LoadSource(Dart_Handle library,
   if (url_str.IsNull()) {
     RETURN_TYPE_ERROR(Z, url, String);
   }
+  if (Dart_IsNull(resolved_url)) {
+    resolved_url = url;
+  }
+  const String& resolved_url_str = Api::UnwrapStringHandle(Z, resolved_url);
+  if (resolved_url_str.IsNull()) {
+    RETURN_TYPE_ERROR(Z, resolved_url, String);
+  }
   const String& source_str = Api::UnwrapStringHandle(Z, source);
   if (source_str.IsNull()) {
     RETURN_TYPE_ERROR(Z, source, String);
@@ -5635,8 +5662,9 @@ DART_EXPORT Dart_Handle Dart_LoadSource(Dart_Handle library,
 
   NoHeapGrowthControlScope no_growth_control;
 
-  const Script& script = Script::Handle(Z,
-      Script::New(url_str, source_str, RawScript::kSourceTag));
+  const Script& script =
+      Script::Handle(Z, Script::New(url_str, resolved_url_str, source_str,
+                                    RawScript::kSourceTag));
   script.SetLocationOffset(line_offset, column_offset);
   Dart_Handle result;
   CompileSource(T, lib, script, &result);
@@ -5667,8 +5695,9 @@ DART_EXPORT Dart_Handle Dart_LibraryLoadPatch(Dart_Handle library,
 
   NoHeapGrowthControlScope no_growth_control;
 
-  const Script& script = Script::Handle(Z,
-      Script::New(url_str, source_str, RawScript::kPatchTag));
+  const Script& script =
+      Script::Handle(Z, Script::New(url_str, url_str, source_str,
+                                    RawScript::kPatchTag));
   Dart_Handle result;
   CompileSource(T, lib, script, &result);
   return result;
@@ -5844,6 +5873,12 @@ DART_EXPORT Dart_Handle Dart_ServiceSendDataEvent(const char* stream_id,
 }
 
 
+DART_EXPORT Dart_Handle Dart_SetFileModifiedCallback(
+    Dart_FileModifiedCallback file_mod_callback) {
+  return Api::Success();
+}
+
+
 DART_EXPORT void Dart_GlobalTimelineSetRecordedStreams(int64_t stream_mask) {
   return;
 }
@@ -5956,6 +5991,30 @@ DART_EXPORT Dart_Handle Dart_ServiceSendDataEvent(const char* stream_id,
 }
 
 
+DART_EXPORT Dart_Handle Dart_SetFileModifiedCallback(
+    Dart_FileModifiedCallback file_modified_callback) {
+  if (!FLAG_support_service) {
+    return Api::Success();
+  }
+  if (file_modified_callback != NULL) {
+    if (IsolateReloadContext::file_modified_callback() != NULL) {
+      return Api::NewError(
+          "%s permits only one callback to be registered, please "
+          "remove the existing callback and then add this callback",
+          CURRENT_FUNC);
+    }
+  } else {
+    if (IsolateReloadContext::file_modified_callback() == NULL) {
+      return Api::NewError(
+          "%s expects 'file_modified_callback' to be set before it is cleared.",
+          CURRENT_FUNC);
+    }
+  }
+  IsolateReloadContext::SetFileModifiedCallback(file_modified_callback);
+  return Api::Success();
+}
+
+
 DART_EXPORT void Dart_GlobalTimelineSetRecordedStreams(int64_t stream_mask) {
   if (!FLAG_support_timeline) {
     return;