Revert "Remove DartSnapshotBuffer and dry up snapshot resolution logi…

…c. (flutter#8640)" (flutter#8644)

This reverts commit 905ddb6.

ci/licenses_golden/licenses_flutter

@@ -383,6 +383,8 @@ FILE: ../../../flutter/runtime/dart_service_isolate.h
 FILE: ../../../flutter/runtime/dart_service_isolate_unittests.cc
 FILE: ../../../flutter/runtime/dart_snapshot.cc
 FILE: ../../../flutter/runtime/dart_snapshot.h
+FILE: ../../../flutter/runtime/dart_snapshot_buffer.cc
+FILE: ../../../flutter/runtime/dart_snapshot_buffer.h
 FILE: ../../../flutter/runtime/dart_vm.cc
 FILE: ../../../flutter/runtime/dart_vm.h
 FILE: ../../../flutter/runtime/dart_vm_data.cc

fml/mapping.cc

@@ -4,18 +4,12 @@
 
 #include "flutter/fml/mapping.h"
 
-#include <sstream>
-
 namespace fml {
 
-// FileMapping
-
 uint8_t* FileMapping::GetMutableMapping() {
   return mutable_mapping_;
 }
 
-// Data Mapping
-
 DataMapping::DataMapping(std::vector<uint8_t> data) : data_(std::move(data)) {}
 
 DataMapping::~DataMapping() = default;
@@ -28,8 +22,6 @@ const uint8_t* DataMapping::GetMapping() const {
   return data_.data();
 }
 
-// NonOwnedMapping
-
 size_t NonOwnedMapping::GetSize() const {
   return size_;
 }
@@ -38,37 +30,4 @@ const uint8_t* NonOwnedMapping::GetMapping() const {
   return data_;
 }
 
-// Symbol Mapping
-
-SymbolMapping::SymbolMapping(fml::RefPtr<fml::NativeLibrary> native_library,
-                             const char* symbol_name)
-    : native_library_(std::move(native_library)) {
-  if (native_library_ && symbol_name != nullptr) {
-    mapping_ = native_library_->ResolveSymbol(symbol_name);
-
-    if (mapping_ == nullptr) {
-      // Apparently, dart_bootstrap seems to account for the Mac behavior of
-      // requiring the underscore prefixed symbol name on non-Mac platforms as
-      // well. As a fallback, check the underscore prefixed variant of the
-      // symbol name and allow callers to not have handle this on a per platform
-      // toolchain quirk basis.
-
-      std::stringstream underscore_symbol_name;
-      underscore_symbol_name << "_" << symbol_name;
-      mapping_ =
-          native_library_->ResolveSymbol(underscore_symbol_name.str().c_str());
-    }
-  }
-}
-
-SymbolMapping::~SymbolMapping() = default;
-
-size_t SymbolMapping::GetSize() const {
-  return 0;
-}
-
-const uint8_t* SymbolMapping::GetMapping() const {
-  return mapping_;
-}
-
 }  // namespace fml

fml/mapping.h

@@ -13,7 +13,6 @@
 #include "flutter/fml/build_config.h"
 #include "flutter/fml/file.h"
 #include "flutter/fml/macros.h"
-#include "flutter/fml/native_library.h"
 #include "flutter/fml/unique_fd.h"
 
 namespace fml {
@@ -32,7 +31,7 @@ class Mapping {
   FML_DISALLOW_COPY_AND_ASSIGN(Mapping);
 };
 
-class FileMapping final : public Mapping {
+class FileMapping : public Mapping {
  public:
   enum class Protection {
     kRead,
@@ -46,10 +45,8 @@ class FileMapping final : public Mapping {
 
   ~FileMapping() override;
 
-  // |Mapping|
   size_t GetSize() const override;
 
-  // |Mapping|
   const uint8_t* GetMapping() const override;
 
   uint8_t* GetMutableMapping();
@@ -66,16 +63,14 @@ class FileMapping final : public Mapping {
   FML_DISALLOW_COPY_AND_ASSIGN(FileMapping);
 };
 
-class DataMapping final : public Mapping {
+class DataMapping : public Mapping {
  public:
   DataMapping(std::vector<uint8_t> data);
 
   ~DataMapping() override;
 
-  // |Mapping|
   size_t GetSize() const override;
 
-  // |Mapping|
   const uint8_t* GetMapping() const override;
 
  private:
@@ -84,15 +79,13 @@ class DataMapping final : public Mapping {
   FML_DISALLOW_COPY_AND_ASSIGN(DataMapping);
 };
 
-class NonOwnedMapping final : public Mapping {
+class NonOwnedMapping : public Mapping {
  public:
   NonOwnedMapping(const uint8_t* data, size_t size)
       : data_(data), size_(size) {}
 
-  // |Mapping|
   size_t GetSize() const override;
 
-  // |Mapping|
   const uint8_t* GetMapping() const override;
 
  private:
@@ -102,26 +95,6 @@ class NonOwnedMapping final : public Mapping {
   FML_DISALLOW_COPY_AND_ASSIGN(NonOwnedMapping);
 };
 
-class SymbolMapping final : public Mapping {
- public:
-  SymbolMapping(fml::RefPtr<fml::NativeLibrary> native_library,
-                const char* symbol_name);
-
-  ~SymbolMapping() override;
-
-  // |Mapping|
-  size_t GetSize() const override;
-
-  // |Mapping|
-  const uint8_t* GetMapping() const override;
-
- private:
-  fml::RefPtr<fml::NativeLibrary> native_library_;
-  const uint8_t* mapping_ = nullptr;
-
-  FML_DISALLOW_COPY_AND_ASSIGN(SymbolMapping);
-};
-
 }  // namespace fml
 
 #endif  // FLUTTER_FML_MAPPING_H_

runtime/BUILD.gn

@@ -46,6 +46,8 @@ source_set("runtime") {
     "dart_service_isolate.h",
     "dart_snapshot.cc",
     "dart_snapshot.h",
+    "dart_snapshot_buffer.cc",
+    "dart_snapshot_buffer.h",
     "dart_vm.cc",
     "dart_vm.h",
     "dart_vm_data.cc",

runtime/dart_isolate.cc

@@ -679,11 +679,14 @@ DartIsolate::CreateDartVMAndEmbedderObjectPair(
   Dart_Isolate isolate = Dart_CreateIsolate(
       advisory_script_uri,         //
       advisory_script_entrypoint,  //
-      (*embedder_isolate)->GetIsolateSnapshot()->GetDataMapping(),
-      (*embedder_isolate)->GetIsolateSnapshot()->GetInstructionsMapping(),
-      (*embedder_isolate)->GetSharedSnapshot()->GetDataMapping(),
-      (*embedder_isolate)->GetSharedSnapshot()->GetInstructionsMapping(), flags,
-      embedder_isolate.get(), error);
+      (*embedder_isolate)
+          ->GetIsolateSnapshot()
+          ->GetData()
+          ->GetSnapshotPointer(),
+      (*embedder_isolate)->GetIsolateSnapshot()->GetInstructionsIfPresent(),
+      (*embedder_isolate)->GetSharedSnapshot()->GetDataIfPresent(),
+      (*embedder_isolate)->GetSharedSnapshot()->GetInstructionsIfPresent(),
+      flags, embedder_isolate.get(), error);
 
   if (isolate == nullptr) {
     FML_DLOG(ERROR) << *error;