Load v8 snapshots directly from APK (and store them uncompressed)

gin/v8_initializer.cc

 // Copyright 2013 The Chromium 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 "gin/v8_initializer.h"
 
 #include "base/basictypes.h"
 #include "base/files/file.h"
 #include "base/files/file_path.h"
 #include "base/files/memory_mapped_file.h"
 #include "base/logging.h"
 #include "base/metrics/histogram.h"
 #include "base/rand_util.h"
 #include "base/strings/sys_string_conversions.h"
 #include "base/threading/platform_thread.h"
 #include "base/time/time.h"
 #include "crypto/sha2.h"
 
 #if defined(V8_USE_EXTERNAL_STARTUP_DATA)
+#if defined(OS_ANDROID)
+#include "base/android/apk_assets.h"
+#endif
 #if defined(OS_MACOSX)
 #include "base/mac/foundation_util.h"
 #endif  // OS_MACOSX
 #include "base/path_service.h"
 #endif  // V8_USE_EXTERNAL_STARTUP_DATA
 
 namespace gin {
 
 namespace {
 base::MemoryMappedFile* g_mapped_natives = nullptr;
 base::MemoryMappedFile* g_mapped_snapshot = nullptr;
 
 #if defined(V8_USE_EXTERNAL_STARTUP_DATA)
 base::File* g_natives_file = nullptr;
 base::File* g_snapshot_file = nullptr;
 base::MemoryMappedFile::Region g_natives_region;
 base::MemoryMappedFile::Region g_snapshot_region;
 
-#if !defined(OS_MACOSX)
+#if !defined(OS_MACOSX) && !defined(OS_ANDROID)
 const int kV8SnapshotBasePathKey =
-#if defined(OS_ANDROID)
-    base::DIR_ANDROID_APP_DATA;
-#elif defined(OS_POSIX)
+#if defined(OS_POSIX)
     base::DIR_EXE;
 #elif defined(OS_WIN)
     base::DIR_MODULE;
-#endif  // OS_ANDROID
-#endif  // !OS_MACOSX
+#endif  // defined(OS_POSIX)
+#endif  // !defined(OS_MACOSX) && !defined(OS_ANDROID)
 
+#if defined(OS_ANDROID)
+const char kNativesFileName[] = "assets/natives_blob.bin";
+const char kSnapshotFileName[] = "assets/snapshot_blob.bin";

[rmcilroy, 2015/06/15 10:21:02]

this is effective the file path (within the APK) not the filename, right? I
think it would make more sense to have an #ifdef ANDROID in GetV8FilePath which
returns this. Also it might be worth just moving kV8SnapshotBasePathKey in there
(under the #if !defined(OS_MACOSX)) too since it's the only place this is used.

[agrieve, 2015/06/15 14:22:04]

Done.

+#else
 const char kNativesFileName[] = "natives_blob.bin";
 const char kSnapshotFileName[] = "snapshot_blob.bin";
+#endif  // defined(OS_ANDROID)
 
-// Constants for snapshot loading retries taken from:
-//   https://support.microsoft.com/en-us/kb/316609.
-const int kMaxOpenAttempts = 5;
-const int kOpenRetryDelayMillis = 250;
-
+#if !defined(OS_ANDROID)
 void GetV8FilePath(const char* file_name, base::FilePath* path_out) {
 #if !defined(OS_MACOSX)
   base::FilePath data_path;
   PathService::Get(kV8SnapshotBasePathKey, &data_path);
   DCHECK(!data_path.empty());
 
   *path_out = data_path.AppendASCII(file_name);
 #else   // !defined(OS_MACOSX)
   base::ScopedCFTypeRef<CFStringRef> natives_file_name(
       base::SysUTF8ToCFStringRef(file_name));
   *path_out = base::mac::PathForFrameworkBundleResource(natives_file_name);
 #endif  // !defined(OS_MACOSX)
   DCHECK(!path_out->empty());
 }
+#endif  // !defined(OS_ANDROID)
 
 static bool MapV8File(base::File file,
                       base::MemoryMappedFile::Region region,
                       base::MemoryMappedFile** mmapped_file_out) {
   DCHECK(*mmapped_file_out == NULL);
   base::MemoryMappedFile* mmapped_file = *mmapped_file_out =
       new base::MemoryMappedFile;
   if (!mmapped_file->Initialize(file.Pass(), region)) {
     delete mmapped_file;
     *mmapped_file_out = NULL;
     return false;
   }
 
   return true;
 }
 
 base::File OpenV8File(const char* file_name,
                       base::MemoryMappedFile::Region* region_out) {
-  // Re-try logic here is motivated by http://crbug.com/479537
-  // for A/V on Windows (https://support.microsoft.com/en-us/kb/316609).
-
   // These match tools/metrics/histograms.xml
   enum OpenV8FileResult {
     OPENED = 0,
     OPENED_RETRY,
     FAILED_IN_USE,
     FAILED_OTHER,
     MAX_VALUE
   };
+#if defined(OS_ANDROID)
+  base::File file(base::android::OpenApkAsset(file_name, region_out));
+  OpenV8FileResult result = file.IsValid() ? OpenV8FileResult::OPENED
+                                           : OpenV8FileResult::FAILED_OTHER;
+#else
+  // Re-try logic here is motivated by http://crbug.com/479537
+  // for A/V on Windows (https://support.microsoft.com/en-us/kb/316609).
+  const int kMaxOpenAttempts = 5;
+  const int kOpenRetryDelayMillis = 250;
 
   base::FilePath path;
   GetV8FilePath(file_name, &path);
 
   OpenV8FileResult result = OpenV8FileResult::FAILED_IN_USE;
   int flags = base::File::FLAG_OPEN | base::File::FLAG_READ;
   base::File file;
   for (int attempt = 0; attempt < kMaxOpenAttempts; attempt++) {
     file.Initialize(path, flags);
     if (file.IsValid()) {
       *region_out = base::MemoryMappedFile::Region::kWholeFile;
       if (attempt == 0) {
         result = OpenV8FileResult::OPENED;
         break;
       } else {
         result = OpenV8FileResult::OPENED_RETRY;
         break;
       }
     } else if (file.error_details() != base::File::FILE_ERROR_IN_USE) {
       result = OpenV8FileResult::FAILED_OTHER;
       break;
     } else if (kMaxOpenAttempts - 1 != attempt) {
       base::PlatformThread::Sleep(
           base::TimeDelta::FromMilliseconds(kOpenRetryDelayMillis));
     }
   }
+#endif  // defined(OS_ANDROID)
 
   UMA_HISTOGRAM_ENUMERATION("V8.Initializer.OpenV8File.Result",
                             result,
                             OpenV8FileResult::MAX_VALUE);
   return file.Pass();
 }
 
 void OpenNativesFileIfNecessary() {
   if (g_natives_file == nullptr) {
     g_natives_file =
@@ skipping 220 matching lines @@
     *snapshot_data_out =
         reinterpret_cast<const char*>(g_mapped_snapshot->data());
     *snapshot_size_out = static_cast<int>(g_mapped_snapshot->length());
   } else {
     *snapshot_data_out = NULL;
     *snapshot_size_out = 0;
   }
 }
 
 }  // namespace gin