Create an app snapshot of the Dart front end.

runtime/bin/main.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include <stdlib.h>
 #include <string.h>
 #include <stdio.h>
 
 #include "include/dart_api.h"
 #include "include/dart_tools_api.h"
@@ skipping 791 matching lines @@
     }                                                                          \
     Dart_ExitScope();                                                          \
     Dart_ShutdownIsolate();                                                    \
     return NULL;                                                               \
   }
 
 
 static void SnapshotOnExitHook(int64_t exit_code);
 
 
+static const int64_t kAppSnapshotHeaderSize = 5 * sizeof(int64_t);  // NOLINT

[zra, 2017/01/26 20:55:00]

is sizeof(int64_t) not already a constant in platform/globals.h or vm/globals.h?

[rmacnak, 2017/01/26 23:48:45]

Didn't know about these. Added and used kInt64Size.

+static const int64_t kAppSnapshotMagicNumber = 0xf6f6dcdc;
+static const int64_t kAppSnapshotPageSize = 4 * KB;
+
+
+static bool ReadAppSnapshotBlobs(const char* script_name,

[zra, 2017/01/26 20:55:00]

Should these snapshot reading functions be pulled out of main.cc into a separate
.cc file? They're starting to take up a lot of main.cc.

[rmacnak, 2017/01/26 23:48:45]

Good point, I'll factor this out in a future CL.

+                                 const uint8_t** vm_data_buffer,
+                                 const uint8_t** vm_instructions_buffer,
+                                 const uint8_t** isolate_data_buffer,
+                                 const uint8_t** isolate_instructions_buffer) {
+  File* file = File::Open(script_name, File::kRead);
+  if (file == NULL) {
+    return false;
+  }
+  if (file->Length() < kAppSnapshotHeaderSize) {
+    file->Release();
+    return false;
+  }
+  int64_t header[5];
+  ASSERT(sizeof(header) == kAppSnapshotHeaderSize);
+  if (!file->ReadFully(&header, kAppSnapshotHeaderSize)) {
+    file->Release();
+    return false;
+  }
+  if (header[0] != kAppSnapshotMagicNumber) {
+    file->Release();
+    return false;
+  }
+
+  int64_t vm_data_size = header[1];
+  int64_t vm_data_position =
+      Utils::RoundUp(file->Position(), kAppSnapshotPageSize);
+  int64_t vm_instructions_size = header[2];
+  int64_t vm_instructions_position = vm_data_position + vm_data_size;
+  if (vm_instructions_size != 0) {
+    vm_instructions_position =
+        Utils::RoundUp(vm_instructions_position, kAppSnapshotPageSize);
+  }
+  int64_t isolate_data_size = header[3];
+  int64_t isolate_data_position = Utils::RoundUp(
+      vm_instructions_position + vm_instructions_size, kAppSnapshotPageSize);
+  int64_t isolate_instructions_size = header[4];
+  int64_t isolate_instructions_position =
+      isolate_data_position + isolate_data_size;
+  if (isolate_instructions_size != 0) {
+    isolate_instructions_position =
+        Utils::RoundUp(isolate_instructions_position, kAppSnapshotPageSize);
+  }
+
+  if (vm_data_size != 0) {
+    *vm_data_buffer = reinterpret_cast<const uint8_t*>(
+        file->Map(File::kReadOnly, vm_data_position, vm_data_size));
+    if (vm_data_buffer == NULL) {
+      Log::PrintErr("Failed to memory map snapshot\n");
+      Platform::Exit(kErrorExitCode);
+    }
+  }
+
+  if (vm_instructions_size != 0) {
+    *vm_instructions_buffer = reinterpret_cast<const uint8_t*>(file->Map(
+        File::kReadExecute, vm_instructions_position, vm_instructions_size));
+    if (*vm_instructions_buffer == NULL) {
+      Log::PrintErr("Failed to memory map snapshot\n");
+      Platform::Exit(kErrorExitCode);
+    }
+  }
+
+  *isolate_data_buffer = reinterpret_cast<const uint8_t*>(
+      file->Map(File::kReadOnly, isolate_data_position, isolate_data_size));
+  if (isolate_data_buffer == NULL) {
+    Log::PrintErr("Failed to memory map snapshot\n");
+    Platform::Exit(kErrorExitCode);
+  }
+
+  if (isolate_instructions_size == 0) {
+    *isolate_instructions_buffer = NULL;
+  } else {
+    *isolate_instructions_buffer = reinterpret_cast<const uint8_t*>(
+        file->Map(File::kReadExecute, isolate_instructions_position,
+                  isolate_instructions_size));
+    if (*isolate_instructions_buffer == NULL) {
+      Log::PrintErr("Failed to memory map snapshot\n");
+      Platform::Exit(kErrorExitCode);
+    }
+  }
+
+  file->Release();
+  return true;
+}
+
+
+#if defined(DART_PRECOMPILED_RUNTIME)
+static bool ReadAppSnapshotDynamicLibrary(
+    const char* script_name,
+    const uint8_t** vm_data_buffer,
+    const uint8_t** vm_instructions_buffer,
+    const uint8_t** isolate_data_buffer,
+    const uint8_t** isolate_instructions_buffer) {
+  void* library = Extensions::LoadExtensionLibrary(script_name);
+  if (library == NULL) {
+    return false;
+  }
+
+  *vm_data_buffer = reinterpret_cast<const uint8_t*>(
+      Extensions::ResolveSymbol(library, kVmSnapshotDataSymbolName));
+  if (*vm_data_buffer == NULL) {
+    Log::PrintErr("Failed to resolve symbol '%s'\n", kVmSnapshotDataSymbolName);
+    Platform::Exit(kErrorExitCode);
+  }
+
+  *vm_instructions_buffer = reinterpret_cast<const uint8_t*>(
+      Extensions::ResolveSymbol(library, kVmSnapshotInstructionsSymbolName));
+  if (*vm_instructions_buffer == NULL) {
+    Log::PrintErr("Failed to resolve symbol '%s'\n",
+                  kVmSnapshotInstructionsSymbolName);
+    Platform::Exit(kErrorExitCode);
+  }
+
+  *isolate_data_buffer = reinterpret_cast<const uint8_t*>(
+      Extensions::ResolveSymbol(library, kIsolateSnapshotDataSymbolName));
+  if (*isolate_data_buffer == NULL) {
+    Log::PrintErr("Failed to resolve symbol '%s'\n",
+                  kIsolateSnapshotDataSymbolName);
+    Platform::Exit(kErrorExitCode);
+  }
+
+  *isolate_instructions_buffer =
+      reinterpret_cast<const uint8_t*>(Extensions::ResolveSymbol(
+          library, kIsolateSnapshotInstructionsSymbolName));
+  if (*isolate_instructions_buffer == NULL) {
+    Log::PrintErr("Failed to resolve symbol '%s'\n",
+                  kIsolateSnapshotInstructionsSymbolName);
+    Platform::Exit(kErrorExitCode);
+  }
+
+  return true;
+}
+#endif  // defined(DART_PRECOMPILED_RUNTIME)
+
+
+static bool ReadAppSnapshot(const char* script_name,
+                            const uint8_t** vm_data_buffer,
+                            const uint8_t** vm_instructions_buffer,
+                            const uint8_t** isolate_data_buffer,
+                            const uint8_t** isolate_instructions_buffer) {
+  if (File::GetType(script_name, true) != File::kIsFile) {
+    // If 'script_name' refers to a pipe, don't read to check for an app
+    // snapshot since we cannot rewind if it isn't (and couldn't mmap it in
+    // anyway if it was).
+    return false;
+  }
+  if (ReadAppSnapshotBlobs(script_name, vm_data_buffer, vm_instructions_buffer,
+                           isolate_data_buffer, isolate_instructions_buffer)) {
+    return true;
+  }
+#if defined(DART_PRECOMPILED_RUNTIME)
+  // For testing AOT with the standalone embedder, we also support loading
+  // from a dynamic library to simulate what happens on iOS.
+  return ReadAppSnapshotDynamicLibrary(
+      script_name, vm_data_buffer, vm_instructions_buffer, isolate_data_buffer,
+      isolate_instructions_buffer);
+#else
+  return false;
+#endif  //  defined(DART_PRECOMPILED_RUNTIME)
+}
+
+
 // Returns true on success, false on failure.
 static Dart_Isolate CreateIsolateAndSetupHelper(bool is_main_isolate,
                                                 const char* script_uri,
                                                 const char* main,
                                                 const char* package_root,
                                                 const char* packages_config,
                                                 Dart_IsolateFlags* flags,
                                                 char** error,
                                                 int* exit_code) {
   ASSERT(script_uri != NULL);
   if (strcmp(script_uri, DART_KERNEL_ISOLATE_NAME) == 0) {
     if (!use_dart_frontend) {
       *error = strdup("Kernel isolate not supported.");
       return NULL;
-    } else {
-      if (packages_config == NULL) {
-        packages_config = commandline_packages_file;
-      }
+    }
+    script_uri = frontend_filename;
+    if (packages_config == NULL) {
+      packages_config = commandline_packages_file;
     }
   }
 
 #if defined(DART_PRECOMPILED_RUNTIME)
   // AOT: All isolates start from the app snapshot.
   bool isolate_run_app_snapshot = true;
   const uint8_t* isolate_snapshot_data = app_isolate_snapshot_data;
   const uint8_t* isolate_snapshot_instructions =
       app_isolate_snapshot_instructions;
 #else
   // JIT: Main isolate starts from the app snapshot, if any. Other isolates
   // use the core libraries snapshot.
   bool isolate_run_app_snapshot = false;
   const uint8_t* isolate_snapshot_data = core_isolate_snapshot_data;
   const uint8_t* isolate_snapshot_instructions =
       core_isolate_snapshot_instructions;
   if ((app_isolate_snapshot_data != NULL) &&
       (is_main_isolate || ((app_script_uri != NULL) &&
                            (strcmp(script_uri, app_script_uri) == 0)))) {
     isolate_run_app_snapshot = true;
     isolate_snapshot_data = app_isolate_snapshot_data;
     isolate_snapshot_instructions = app_isolate_snapshot_instructions;
+  } else if (!is_main_isolate) {
+    const uint8_t* file_vm_snapshot_data = NULL;
+    const uint8_t* file_vm_snapshot_instructions = NULL;
+    const uint8_t* file_isolate_snapshot_data = NULL;
+    const uint8_t* file_isolate_snapshot_instructions = NULL;
+    if (ReadAppSnapshot(
+            script_uri, &file_vm_snapshot_data, &file_vm_snapshot_instructions,
+            &file_isolate_snapshot_data, &file_isolate_snapshot_instructions)) {
+      // TODO(rmacnak): We are leaking the snapshot when the isolate shuts down.

[siva, 2017/01/26 17:07:08]

When you say leaked do you mean it is not unmapped?

If two spawnURI isolates share the same script_uri we will be mapping that file
twice, I guess that is ok.

[rmacnak, 2017/01/26 18:07:13]

Right, it is not unmapped. If a second spawnURI isolate comes in with the same
script uri, we'll consume more virtual memory but no more physical memory.

+      isolate_run_app_snapshot = true;
+      isolate_snapshot_data = file_isolate_snapshot_data;
+      isolate_snapshot_instructions = file_isolate_snapshot_instructions;
+    }
   }
 #endif
 
   // If the script is a Kernel binary, then we will try to bootstrap from the
   // script.
   const uint8_t* kernel_file = NULL;
   intptr_t kernel_length = -1;
   const bool is_kernel =
       !isolate_run_app_snapshot &&
       TryReadKernel(script_uri, &kernel_file, &kernel_length);
@@ skipping 60 matching lines @@
   // Set up various closures, e.g: printing, timers etc.
   // Set up 'package root' for URI resolution.
   result = DartUtils::PrepareForScriptLoading(false, trace_loading);
   CHECK_RESULT(result);
 
   // Set up the load port provided by the service isolate so that we can
   // load scripts.
   result = DartUtils::SetupServiceLoadPort();
   CHECK_RESULT(result);
 
-  if (Dart_IsKernelIsolate(isolate)) {
-    script_uri = frontend_filename;
-  }
-
   // Setup package root if specified.
   result = DartUtils::SetupPackageRoot(package_root, packages_config);
   CHECK_RESULT(result);
 
   result = Dart_SetEnvironmentCallback(EnvironmentCallback);
   CHECK_RESULT(result);
 
   if (!Dart_IsKernelIsolate(isolate) && use_dart_frontend) {
     // This must be the main script to be loaded. Wait for Kernel isolate
     // to finish initialization.
@@ skipping 335 matching lines @@
     ErrorExit(kErrorExitCode, "Unable to write file %s for writing snapshot\n",
               filename);
   }
   file->Release();
   if (concat != NULL) {
     delete concat;
   }
 }
 
 
-static const int64_t kAppSnapshotHeaderSize = 5 * sizeof(int64_t);  // NOLINT
-static const int64_t kAppSnapshotMagicNumber = 0xf6f6dcdc;
-static const int64_t kAppSnapshotPageSize = 4 * KB;
-
-
-static bool ReadAppSnapshotBlobs(const char* script_name,
-                                 const uint8_t** vm_data_buffer,
-                                 const uint8_t** vm_instructions_buffer,
-                                 const uint8_t** isolate_data_buffer,
-                                 const uint8_t** isolate_instructions_buffer) {
-  File* file = File::Open(script_name, File::kRead);
-  if (file == NULL) {
-    return false;
-  }
-  if (file->Length() < kAppSnapshotHeaderSize) {
-    file->Release();
-    return false;
-  }
-  int64_t header[5];
-  ASSERT(sizeof(header) == kAppSnapshotHeaderSize);
-  if (!file->ReadFully(&header, kAppSnapshotHeaderSize)) {
-    file->Release();
-    return false;
-  }
-  if (header[0] != kAppSnapshotMagicNumber) {
-    file->Release();
-    return false;
-  }
-
-  int64_t vm_data_size = header[1];
-  int64_t vm_data_position =
-      Utils::RoundUp(file->Position(), kAppSnapshotPageSize);
-  int64_t vm_instructions_size = header[2];
-  int64_t vm_instructions_position = vm_data_position + vm_data_size;
-  if (vm_instructions_size != 0) {
-    vm_instructions_position =
-        Utils::RoundUp(vm_instructions_position, kAppSnapshotPageSize);
-  }
-  int64_t isolate_data_size = header[3];
-  int64_t isolate_data_position = Utils::RoundUp(
-      vm_instructions_position + vm_instructions_size, kAppSnapshotPageSize);
-  int64_t isolate_instructions_size = header[4];
-  int64_t isolate_instructions_position =
-      isolate_data_position + isolate_data_size;
-  if (isolate_instructions_size != 0) {
-    isolate_instructions_position =
-        Utils::RoundUp(isolate_instructions_position, kAppSnapshotPageSize);
-  }
-
-  if (vm_data_size != 0) {
-    *vm_data_buffer = reinterpret_cast<const uint8_t*>(
-        file->Map(File::kReadOnly, vm_data_position, vm_data_size));
-    if (vm_data_buffer == NULL) {
-      Log::PrintErr("Failed to memory map snapshot\n");
-      Platform::Exit(kErrorExitCode);
-    }
-  }
-
-  if (vm_instructions_size != 0) {
-    *vm_instructions_buffer = reinterpret_cast<const uint8_t*>(file->Map(
-        File::kReadExecute, vm_instructions_position, vm_instructions_size));
-    if (*vm_instructions_buffer == NULL) {
-      Log::PrintErr("Failed to memory map snapshot\n");
-      Platform::Exit(kErrorExitCode);
-    }
-  }
-
-  *isolate_data_buffer = reinterpret_cast<const uint8_t*>(
-      file->Map(File::kReadOnly, isolate_data_position, isolate_data_size));
-  if (isolate_data_buffer == NULL) {
-    Log::PrintErr("Failed to memory map snapshot\n");
-    Platform::Exit(kErrorExitCode);
-  }
-
-  if (isolate_instructions_size == 0) {
-    *isolate_instructions_buffer = NULL;
-  } else {
-    *isolate_instructions_buffer = reinterpret_cast<const uint8_t*>(
-        file->Map(File::kReadExecute, isolate_instructions_position,
-                  isolate_instructions_size));
-    if (*isolate_instructions_buffer == NULL) {
-      Log::PrintErr("Failed to memory map snapshot\n");
-      Platform::Exit(kErrorExitCode);
-    }
-  }
-
-  file->Release();
-  return true;
-}
-
-
-#if defined(DART_PRECOMPILED_RUNTIME)
-static bool ReadAppSnapshotDynamicLibrary(
-    const char* script_name,
-    const uint8_t** vm_data_buffer,
-    const uint8_t** vm_instructions_buffer,
-    const uint8_t** isolate_data_buffer,
-    const uint8_t** isolate_instructions_buffer) {
-  void* library = Extensions::LoadExtensionLibrary(script_name);
-  if (library == NULL) {
-    return false;
-  }
-
-  *vm_data_buffer = reinterpret_cast<const uint8_t*>(
-      Extensions::ResolveSymbol(library, kVmSnapshotDataSymbolName));
-  if (*vm_data_buffer == NULL) {
-    Log::PrintErr("Failed to resolve symbol '%s'\n", kVmSnapshotDataSymbolName);
-    Platform::Exit(kErrorExitCode);
-  }
-
-  *vm_instructions_buffer = reinterpret_cast<const uint8_t*>(
-      Extensions::ResolveSymbol(library, kVmSnapshotInstructionsSymbolName));
-  if (*vm_instructions_buffer == NULL) {
-    Log::PrintErr("Failed to resolve symbol '%s'\n",
-                  kVmSnapshotInstructionsSymbolName);
-    Platform::Exit(kErrorExitCode);
-  }
-
-  *isolate_data_buffer = reinterpret_cast<const uint8_t*>(
-      Extensions::ResolveSymbol(library, kIsolateSnapshotDataSymbolName));
-  if (*isolate_data_buffer == NULL) {
-    Log::PrintErr("Failed to resolve symbol '%s'\n",
-                  kIsolateSnapshotDataSymbolName);
-    Platform::Exit(kErrorExitCode);
-  }
-
-  *isolate_instructions_buffer =
-      reinterpret_cast<const uint8_t*>(Extensions::ResolveSymbol(
-          library, kIsolateSnapshotInstructionsSymbolName));
-  if (*isolate_instructions_buffer == NULL) {
-    Log::PrintErr("Failed to resolve symbol '%s'\n",
-                  kIsolateSnapshotInstructionsSymbolName);
-    Platform::Exit(kErrorExitCode);
-  }
-
-  return true;
-}
-#endif  // defined(DART_PRECOMPILED_RUNTIME)
-
-
-static bool ReadAppSnapshot(const char* script_name,
-                            const uint8_t** vm_data_buffer,
-                            const uint8_t** vm_instructions_buffer,
-                            const uint8_t** isolate_data_buffer,
-                            const uint8_t** isolate_instructions_buffer) {
-  if (File::GetType(script_name, true) != File::kIsFile) {
-    // If 'script_name' refers to a pipe, don't read to check for an app
-    // snapshot since we cannot rewind if it isn't (and couldn't mmap it in
-    // anyway if it was).
-    return false;
-  }
-  if (ReadAppSnapshotBlobs(script_name, vm_data_buffer, vm_instructions_buffer,
-                           isolate_data_buffer, isolate_instructions_buffer)) {
-    return true;
-  }
-#if defined(DART_PRECOMPILED_RUNTIME)
-  // For testing AOT with the standalone embedder, we also support loading
-  // from a dynamic library to simulate what happens on iOS.
-  return ReadAppSnapshotDynamicLibrary(
-      script_name, vm_data_buffer, vm_instructions_buffer, isolate_data_buffer,
-      isolate_instructions_buffer);
-#else
-  return false;
-#endif  //  defined(DART_PRECOMPILED_RUNTIME)
-}
-
-
 static bool WriteInt64(File* file, int64_t size) {
   return file->WriteFully(&size, sizeof(size));
 }
 
 
 static void WriteAppSnapshot(const char* filename,
                              uint8_t* vm_data_buffer,
                              intptr_t vm_data_size,
                              uint8_t* vm_instructions_buffer,
                              intptr_t vm_instructions_size,
@@ skipping 594 matching lines @@
   Platform::Exit(Process::GlobalExitCode());
 }
 
 }  // namespace bin
 }  // namespace dart
 
 int main(int argc, char** argv) {
   dart::bin::main(argc, argv);
   UNREACHABLE();
 }