Sketch of on demand snapshot generation for d8

src/mksnapshot.cc

 // Copyright 2006-2008 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#include <errno.h>
-#include <signal.h>
-#include <stdio.h>
-
 #include "src/v8.h"
 
-#include "include/libplatform/libplatform.h"
-#include "src/assembler.h"
-#include "src/base/platform/platform.h"
-#include "src/bootstrapper.h"
-#include "src/flags.h"
-#include "src/list.h"
-#include "src/natives.h"
-#include "src/serialize.h"
-
-
-using namespace v8;
-
-
-class Compressor {
- public:
-  virtual ~Compressor() {}
-  virtual bool Compress(i::Vector<i::byte> input) = 0;
-  virtual i::Vector<i::byte>* output() = 0;
-};
-
-
-class SnapshotWriter {
- public:
-  explicit SnapshotWriter(const char* snapshot_file)
-      : fp_(GetFileDescriptorOrDie(snapshot_file))
-      , raw_file_(NULL)
-      , raw_context_file_(NULL)
-      , startup_blob_file_(NULL)
-      , compressor_(NULL) {
-  }
-
-  ~SnapshotWriter() {
-    fclose(fp_);
-    if (raw_file_) fclose(raw_file_);
-    if (raw_context_file_) fclose(raw_context_file_);
-    if (startup_blob_file_) fclose(startup_blob_file_);
-  }
-
-  void SetCompressor(Compressor* compressor) {
-    compressor_ = compressor;
-  }
-
-  void SetRawFiles(const char* raw_file, const char* raw_context_file) {
-    raw_file_ = GetFileDescriptorOrDie(raw_file);
-    raw_context_file_ = GetFileDescriptorOrDie(raw_context_file);
-  }
-
-  void SetStartupBlobFile(const char* startup_blob_file) {
-    if (startup_blob_file != NULL)
-      startup_blob_file_ = GetFileDescriptorOrDie(startup_blob_file);
-  }
-
-  void WriteSnapshot(const i::List<i::byte>& snapshot_data,
-                     const i::Serializer& serializer,
-                     const i::List<i::byte>& context_snapshot_data,
-                     const i::Serializer& context_serializer) const {
-    WriteSnapshotFile(snapshot_data, serializer,
-                      context_snapshot_data, context_serializer);
-    MaybeWriteStartupBlob(snapshot_data, serializer,
-                          context_snapshot_data, context_serializer);
-  }
-
- private:
-  void MaybeWriteStartupBlob(const i::List<i::byte>& snapshot_data,
-                             const i::Serializer& serializer,
-                             const i::List<i::byte>& context_snapshot_data,
-                             const i::Serializer& context_serializer) const {
-    if (!startup_blob_file_) return;
-
-    i::SnapshotByteSink sink;
-
-    int spaces[] = {i::NEW_SPACE,           i::OLD_POINTER_SPACE,
-                    i::OLD_DATA_SPACE,      i::CODE_SPACE,
-                    i::MAP_SPACE,           i::CELL_SPACE,
-                    i::PROPERTY_CELL_SPACE, i::LO_SPACE};
-
-    i::byte* snapshot_bytes = snapshot_data.begin();
-    sink.PutBlob(snapshot_bytes, snapshot_data.length(), "snapshot");
-    for (size_t i = 0; i < arraysize(spaces); ++i) {
-      i::Vector<const uint32_t> chunks =
-          serializer.FinalAllocationChunks(spaces[i]);
-      // For the start-up snapshot, none of the reservations has more than
-      // one chunk (reservation for each space fits onto a single page).
-      CHECK_EQ(1, chunks.length());
-      sink.PutInt(chunks[0], "spaces");
-    }
-
-    i::byte* context_bytes = context_snapshot_data.begin();
-    sink.PutBlob(context_bytes, context_snapshot_data.length(), "context");
-    for (size_t i = 0; i < arraysize(spaces); ++i) {
-      i::Vector<const uint32_t> chunks =
-          context_serializer.FinalAllocationChunks(spaces[i]);
-      // For the context snapshot, none of the reservations has more than
-      // one chunk (reservation for each space fits onto a single page).
-      CHECK_EQ(1, chunks.length());
-      sink.PutInt(chunks[0], "spaces");
-    }
-
-    const i::List<i::byte>& startup_blob = sink.data();
-    size_t written = fwrite(startup_blob.begin(), 1, startup_blob.length(),
-                            startup_blob_file_);
-    if (written != static_cast<size_t>(startup_blob.length())) {
-      i::PrintF("Writing snapshot file failed.. Aborting.\n");
-      exit(1);
-    }
-  }
-
-  void WriteSnapshotFile(const i::List<i::byte>& snapshot_data,
-                         const i::Serializer& serializer,
-                         const i::List<i::byte>& context_snapshot_data,
-                         const i::Serializer& context_serializer) const {
-    WriteFilePrefix();
-    WriteData("", snapshot_data, raw_file_);
-    WriteData("context_", context_snapshot_data, raw_context_file_);
-    WriteMeta("context_", context_serializer);
-    WriteMeta("", serializer);
-    WriteFileSuffix();
-  }
-
-  void WriteFilePrefix() const {
-    fprintf(fp_, "// Autogenerated snapshot file. Do not edit.\n\n");
-    fprintf(fp_, "#include \"src/v8.h\"\n");
-    fprintf(fp_, "#include \"src/base/platform/platform.h\"\n\n");
-    fprintf(fp_, "#include \"src/snapshot.h\"\n\n");
-    fprintf(fp_, "namespace v8 {\n");
-    fprintf(fp_, "namespace internal {\n\n");
-  }
-
-  void WriteFileSuffix() const {
-    fprintf(fp_, "}  // namespace internal\n");
-    fprintf(fp_, "}  // namespace v8\n");
-  }
-
-  void WriteData(const char* prefix, const i::List<i::byte>& source_data,
-                 FILE* raw_file) const {
-    const i::List<i::byte>* data_to_be_written = NULL;
-    i::List<i::byte> compressed_data;
-    if (!compressor_) {
-      data_to_be_written = &source_data;
-    } else if (compressor_->Compress(source_data.ToVector())) {
-      compressed_data.AddAll(*compressor_->output());
-      data_to_be_written = &compressed_data;
-    } else {
-      i::PrintF("Compression failed. Aborting.\n");
-      exit(1);
-    }
-
-    DCHECK(data_to_be_written);
-    MaybeWriteRawFile(data_to_be_written, raw_file);
-    WriteData(prefix, source_data, data_to_be_written);
-  }
-
-  void MaybeWriteRawFile(const i::List<i::byte>* data, FILE* raw_file) const {
-    if (!data || !raw_file)
-      return;
-
-    // Sanity check, whether i::List iterators truly return pointers to an
-    // internal array.
-    DCHECK(data->end() - data->begin() == data->length());
-
-    size_t written = fwrite(data->begin(), 1, data->length(), raw_file);
-    if (written != (size_t)data->length()) {
-      i::PrintF("Writing raw file failed.. Aborting.\n");
-      exit(1);
-    }
-  }
-
-  void WriteData(const char* prefix, const i::List<i::byte>& source_data,
-                 const i::List<i::byte>* data_to_be_written) const {
-    fprintf(fp_, "const byte Snapshot::%sdata_[] = {\n", prefix);
-    WriteSnapshotData(data_to_be_written);
-    fprintf(fp_, "};\n");
-    fprintf(fp_, "const int Snapshot::%ssize_ = %d;\n", prefix,
-            data_to_be_written->length());
-
-    if (data_to_be_written == &source_data) {
-      fprintf(fp_, "const byte* Snapshot::%sraw_data_ = Snapshot::%sdata_;\n",
-              prefix, prefix);
-      fprintf(fp_, "const int Snapshot::%sraw_size_ = Snapshot::%ssize_;\n",
-              prefix, prefix);
-    } else {
-      fprintf(fp_, "const byte* Snapshot::%sraw_data_ = NULL;\n", prefix);
-      fprintf(fp_, "const int Snapshot::%sraw_size_ = %d;\n",
-              prefix, source_data.length());
-    }
-    fprintf(fp_, "\n");
-  }
-
-  void WriteMeta(const char* prefix, const i::Serializer& ser) const {
-    WriteSizeVar(ser, prefix, "new", i::NEW_SPACE);
-    WriteSizeVar(ser, prefix, "pointer", i::OLD_POINTER_SPACE);
-    WriteSizeVar(ser, prefix, "data", i::OLD_DATA_SPACE);
-    WriteSizeVar(ser, prefix, "code", i::CODE_SPACE);
-    WriteSizeVar(ser, prefix, "map", i::MAP_SPACE);
-    WriteSizeVar(ser, prefix, "cell", i::CELL_SPACE);
-    WriteSizeVar(ser, prefix, "property_cell", i::PROPERTY_CELL_SPACE);
-    WriteSizeVar(ser, prefix, "lo", i::LO_SPACE);
-    fprintf(fp_, "\n");
-  }
-
-  void WriteSizeVar(const i::Serializer& ser, const char* prefix,
-                    const char* name, int space) const {
-    i::Vector<const uint32_t> chunks = ser.FinalAllocationChunks(space);
-    // For the start-up snapshot, none of the reservations has more than
-    // one chunk (total reservation fits into a single page).
-    CHECK_EQ(1, chunks.length());
-    fprintf(fp_, "const int Snapshot::%s%s_space_used_ = %d;\n", prefix, name,
-            chunks[0]);
-  }
-
-  void WriteSnapshotData(const i::List<i::byte>* data) const {
-    for (int i = 0; i < data->length(); i++) {
-      if ((i & 0x1f) == 0x1f)
-        fprintf(fp_, "\n");
-      if (i > 0)
-        fprintf(fp_, ",");
-      fprintf(fp_, "%u", static_cast<unsigned char>(data->at(i)));
-    }
-    fprintf(fp_, "\n");
-  }
-
-  FILE* GetFileDescriptorOrDie(const char* filename) {
-    FILE* fp = base::OS::FOpen(filename, "wb");
-    if (fp == NULL) {
-      i::PrintF("Unable to open file \"%s\" for writing.\n", filename);
-      exit(1);
-    }
-    return fp;
-  }
-
-  FILE* fp_;
-  FILE* raw_file_;
-  FILE* raw_context_file_;
-  FILE* startup_blob_file_;
-  Compressor* compressor_;
-};
-
-
-void DumpException(Handle<Message> message) {
-  String::Utf8Value message_string(message->Get());
-  String::Utf8Value message_line(message->GetSourceLine());
-  fprintf(stderr, "%s at line %d\n", *message_string, message->GetLineNumber());
-  fprintf(stderr, "%s\n", *message_line);
-  for (int i = 0; i <= message->GetEndColumn(); ++i) {
-    fprintf(stderr, "%c", i < message->GetStartColumn() ? ' ' : '^');
-  }
-  fprintf(stderr, "\n");
-}
-
-
 int main(int argc, char** argv) {
   // By default, log code create information in the snapshot.
   i::FLAG_log_code = true;
 
   // Omit from the snapshot natives for features that can be turned off
   // at runtime.
   i::FLAG_harmony_shipping = false;
 
   // Print the usage if an error occurs when parsing the command line
   // flags or if the help flag is set.
   int result = i::FlagList::SetFlagsFromCommandLine(&argc, argv, true);
   if (result > 0 || argc != 2 || i::FLAG_help) {
     ::printf("Usage: %s [flag] ... outfile\n", argv[0]);
     i::FlagList::PrintHelp();
     return !i::FLAG_help;
   }
 
-  i::CpuFeatures::Probe(true);
-  V8::InitializeICU();
-  v8::Platform* platform = v8::platform::CreateDefaultPlatform();
-  v8::V8::InitializePlatform(platform);
-  v8::V8::Initialize();
-
   i::FLAG_logfile_per_isolate = false;
 
-  Isolate::CreateParams params;
-  params.enable_serializer = true;
-  Isolate* isolate = v8::Isolate::New(params);
-  { Isolate::Scope isolate_scope(isolate);
-    i::Isolate* internal_isolate = reinterpret_cast<i::Isolate*>(isolate);
-
-    Persistent<Context> context;
-    {
-      HandleScope handle_scope(isolate);
-      context.Reset(isolate, Context::New(isolate));
-    }
-
-    if (context.IsEmpty()) {
-      fprintf(stderr,
-              "\nException thrown while compiling natives - see above.\n\n");
-      exit(1);
-    }
-    if (i::FLAG_extra_code != NULL) {
-      // Capture 100 frames if anything happens.
-      V8::SetCaptureStackTraceForUncaughtExceptions(true, 100);
-      HandleScope scope(isolate);
-      v8::Context::Scope cscope(v8::Local<v8::Context>::New(isolate, context));
-      const char* name = i::FLAG_extra_code;
-      FILE* file = base::OS::FOpen(name, "rb");
-      if (file == NULL) {
-        fprintf(stderr, "Failed to open '%s': errno %d\n", name, errno);
-        exit(1);
-      }
-
-      fseek(file, 0, SEEK_END);
-      int size = ftell(file);
-      rewind(file);
-
-      char* chars = new char[size + 1];
-      chars[size] = '\0';
-      for (int i = 0; i < size;) {
-        int read = static_cast<int>(fread(&chars[i], 1, size - i, file));
-        if (read < 0) {
-          fprintf(stderr, "Failed to read '%s': errno %d\n", name, errno);
-          exit(1);
-        }
-        i += read;
-      }
-      fclose(file);
-      Local<String> source = String::NewFromUtf8(isolate, chars);
-      TryCatch try_catch;
-      Local<Script> script = Script::Compile(source);
-      if (try_catch.HasCaught()) {
-        fprintf(stderr, "Failure compiling '%s'\n", name);
-        DumpException(try_catch.Message());
-        exit(1);
-      }
-      script->Run();
-      if (try_catch.HasCaught()) {
-        fprintf(stderr, "Failure running '%s'\n", name);
-        DumpException(try_catch.Message());
-        exit(1);
-      }
-    }
-    // Make sure all builtin scripts are cached.
-    { HandleScope scope(isolate);
-      for (int i = 0; i < i::Natives::GetBuiltinsCount(); i++) {
-        internal_isolate->bootstrapper()->NativesSourceLookup(i);
-      }
-    }
-    // If we don't do this then we end up with a stray root pointing at the
-    // context even after we have disposed of the context.
-    internal_isolate->heap()->CollectAllAvailableGarbage("mksnapshot");
-    i::Object* raw_context = *v8::Utils::OpenPersistent(context);
-    context.Reset();
-
-    // This results in a somewhat smaller snapshot, probably because it gets
-    // rid of some things that are cached between garbage collections.
-    i::SnapshotByteSink snapshot_sink;
-    i::StartupSerializer ser(internal_isolate, &snapshot_sink);
-    ser.SerializeStrongReferences();
-
-    i::SnapshotByteSink context_sink;
-    i::PartialSerializer context_ser(internal_isolate, &ser, &context_sink);
-    context_ser.Serialize(&raw_context);
-    ser.SerializeWeakReferences();
-
-    context_ser.FinalizeAllocation();
-    ser.FinalizeAllocation();
-
-    {
-      SnapshotWriter writer(argv[1]);
-      if (i::FLAG_raw_file && i::FLAG_raw_context_file)
-        writer.SetRawFiles(i::FLAG_raw_file, i::FLAG_raw_context_file);
-      if (i::FLAG_startup_blob)
-        writer.SetStartupBlobFile(i::FLAG_startup_blob);
-      writer.WriteSnapshot(snapshot_sink.data(), ser, context_sink.data(),
-                           context_ser);
-    }
-  }
-
-  isolate->Dispose();
-  V8::Dispose();
-  V8::ShutdownPlatform();
-  delete platform;
+  v8::V8::CreateV8Snapshot(i::FLAG_raw_file, i::FLAG_raw_context_file,
+      i::FLAG_startup_blob, i::FLAG_extra_code, argv[1]);
   return 0;
 }