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/memory/scoped_ptr.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 {
 
@@ skipping 11 matching lines @@
 #endif
 
 // File handles intentionally never closed. Not using File here because its
 // Windows implementation guards against two instances owning the same
 // PlatformFile (which we allow since we know it is never freed).
 base::PlatformFile g_natives_pf = kInvalidPlatformFile;
 base::PlatformFile g_snapshot_pf = kInvalidPlatformFile;
 base::MemoryMappedFile::Region g_natives_region;
 base::MemoryMappedFile::Region g_snapshot_region;
 
-#if !defined(OS_MACOSX)
-const int kV8SnapshotBasePathKey =
-#if defined(OS_ANDROID)
-    base::DIR_ANDROID_APP_DATA;
-#elif defined(OS_POSIX)
-    base::DIR_EXE;
-#elif defined(OS_WIN)
-    base::DIR_MODULE;
-#endif  // OS_ANDROID
-#endif  // !OS_MACOSX
-
 const char kNativesFileName[] = "natives_blob.bin";
 const char kSnapshotFileName[] = "snapshot_blob.bin";
 
-// Constants for snapshot loading retries taken from:
-//   https://support.microsoft.com/en-us/kb/316609.
-const int kMaxOpenAttempts = 5;
-const int kOpenRetryDelayMillis = 250;
-
 void GetV8FilePath(const char* file_name, base::FilePath* path_out) {
 #if !defined(OS_MACOSX)
   base::FilePath data_path;
-  PathService::Get(kV8SnapshotBasePathKey, &data_path);
+#if defined(OS_ANDROID)
+  // This is the path within the .apk.
+  data_path = base::FilePath(FILE_PATH_LITERAL("assets"));
+#elif defined(OS_POSIX)
+  PathService::Get(base::DIR_EXE, &data_path);
+#elif defined(OS_WIN)
+  PathService::Get(base::DIR_MODULE, &data_path);
+#endif
   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());
 }
@@ skipping 16 matching lines @@
   // 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
   };
-
   base::FilePath path;
   GetV8FilePath(file_name, &path);
 
+#if defined(OS_ANDROID)
+  base::File file(base::android::OpenApkAsset(path.value(), 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;
+
   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.TakePlatformFile();
 }
 
 void OpenNativesFileIfNecessary() {
   if (g_natives_pf == kInvalidPlatformFile) {
     g_natives_pf = OpenV8File(kNativesFileName, &g_natives_region);
@@ skipping 216 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