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

gin/v8_initializer.cc

Index: gin/v8_initializer.cc
diff --git a/gin/v8_initializer.cc b/gin/v8_initializer.cc
index 0568fe77db9300785c3830a0461028d93e89b47c..66894cabf6bdca04d946ef84c343e40e5daeabce 100644
--- a/gin/v8_initializer.cc
+++ b/gin/v8_initializer.cc
@@ -17,6 +17,9 @@
 #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
@@ -42,14 +45,20 @@ const int kV8SnapshotBasePathKey =
 #endif  // OS_ANDROID
 #endif  // !OS_MACOSX
 
+#if defined(OS_ANDROID)
+const char kNativesFileName[] = "assets/natives_blob.bin";
+const char kSnapshotFileName[] = "assets/snapshot_blob.bin";
+#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;
@@ -64,6 +73,7 @@ void GetV8FilePath(const char* file_name, base::FilePath* path_out) {
 #endif  // !defined(OS_MACOSX)
   DCHECK(!path_out->empty());
 }
+#endif  // !defined(OS_ANDROID)
 
 static bool MapV8File(base::File file,
                       base::MemoryMappedFile::Region region,
@@ -80,9 +90,11 @@ static bool MapV8File(base::File file,
   return true;
 }
 
-static bool OpenV8File(const base::FilePath& path,
-                       int flags,
-                       base::File& file) {
+base::File OpenV8File(const char* file_name,
+    base::MemoryMappedFile::Region* out_region) {

[rmcilroy, 2015/06/09 11:52:55]

nit - usual convention is to suffix with "_out" rather than prefix (i.e.,
region_out here)

[rmcilroy, 2015/06/09 11:52:55]

align arguments (or run "git cl format" :))

+#if defined(OS_ANDROID)
+  return base::File(base::android::OpenApkAsset(file_name, out_region));
+#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).
 
@@ -95,10 +107,15 @@ static bool OpenV8File(const base::FilePath& path,
     MAX_VALUE
   };
 
+  int flags = base::File::FLAG_OPEN | base::File::FLAG_READ;

[rmcilroy, 2015/06/09 11:52:54]

nit - move flags down below with OpenV8FileResult result and add a newline
between "GetV8FilePath..." and "OpenV8FileResult result ..."

+  base::FilePath path;
+  GetV8FilePath(file_name, &path);
   OpenV8FileResult result = OpenV8FileResult::FAILED_IN_USE;
+  base::File file;
   for (int attempt = 0; attempt < kMaxOpenAttempts; attempt++) {
     file.Initialize(path, flags);
     if (file.IsValid()) {
+      *out_region = base::MemoryMappedFile::Region::kWholeFile;
       if (attempt == 0) {
         result = OpenV8FileResult::OPENED;
         break;
@@ -118,9 +135,8 @@ static bool OpenV8File(const base::FilePath& path,
   UMA_HISTOGRAM_ENUMERATION("V8.Initializer.OpenV8File.Result",
                             result,
                             OpenV8FileResult::MAX_VALUE);
-
-  return result == OpenV8FileResult::OPENED
-         || result == OpenV8FileResult::OPENED_RETRY;
+  return file.Pass();
+#endif  // defined(OS_ANDROID)
 }
 
 #if defined(V8_VERIFY_EXTERNAL_STARTUP_DATA)
@@ -169,16 +185,12 @@ static LoadV8FileResult OpenMapVerify(
     const unsigned char* fingerprint,
 #endif
     base::MemoryMappedFile** mmapped_file_out) {
-  base::FilePath path;
-  GetV8FilePath(file_name, &path);
+  base::MemoryMappedFile::Region region;
 
-  base::File file;
-  int flags = base::File::FLAG_OPEN | base::File::FLAG_READ;
-
-  if (!OpenV8File(path, flags, file))
+  base::File file(OpenV8File(file_name, &region));
+  if (!file.IsValid())
     return V8_LOAD_FAILED_OPEN;
-  if (!MapV8File(file.Pass(), base::MemoryMappedFile::Region::kWholeFile,
-                 mmapped_file_out))
+  if (!MapV8File(file.Pass(), region, mmapped_file_out))
     return V8_LOAD_FAILED_MAP;
 #if defined(V8_VERIFY_EXTERNAL_STARTUP_DATA)
   if (!VerifyV8StartupFile(mmapped_file_out, fingerprint))
@@ -197,6 +209,8 @@ void V8Initializer::LoadV8Snapshot() {
                                           g_snapshot_fingerprint,
 #endif
                                           &g_mapped_snapshot);
+  // V8 can't start up without the source of the natives, but it can
+  // start up (slower) without the snapshot.

[rmcilroy, 2015/06/09 11:52:54]

nit - probably clearer as "Failure to load the V8 snapshot is not necessarily an
error. V8 can start up (slower) without the snapshot" (no need to mention
natives here I don't think.

   UMA_HISTOGRAM_ENUMERATION("V8.Initializer.LoadV8Snapshot.Result", result,
                             V8_LOAD_MAX_VALUE);
 }
@@ -270,34 +284,25 @@ void V8Initializer::LoadV8NativesFromFD(base::PlatformFile natives_pf,
 #endif  // V8_VERIFY_EXTERNAL_STARTUP_DATA
 }
 
-// static
-bool V8Initializer::OpenV8FilesForChildProcesses(
-    base::PlatformFile* natives_fd_out,
-    base::PlatformFile* snapshot_fd_out) {
-  base::FilePath natives_data_path;
-  base::FilePath snapshot_data_path;
-  GetV8FilePath(kNativesFileName, &natives_data_path);
-  GetV8FilePath(kSnapshotFileName, &snapshot_data_path);
-
-  base::File natives_data_file;
-  base::File snapshot_data_file;
-  int file_flags = base::File::FLAG_OPEN | base::File::FLAG_READ;
-
-  bool natives_success =
-      OpenV8File(natives_data_path, file_flags, natives_data_file);
-  if (natives_success) {
-    *natives_fd_out = natives_data_file.TakePlatformFile();
-  }
-  bool snapshot_success =
-      OpenV8File(snapshot_data_path, file_flags, snapshot_data_file);
-  if (snapshot_success) {
-    *snapshot_fd_out = snapshot_data_file.TakePlatformFile();
-  }
-  // We can start up without the snapshot file, but not without the natives.
-  return natives_success;
+#if defined(OS_POSIX)
+V8Initializer::V8Files::V8Files() {

[rmcilroy, 2015/06/09 11:52:54]

initialize the fds to "-1" 

 }
 
-#endif  // V8_USE_EXTERNAL_STARTUP_DATA
+V8Initializer::V8Files::~V8Files() {
+}
+
+// static
+void V8Initializer::OpenV8FilesForChildProcesses(
+    V8Initializer::V8Files* files_out) {
+  base::File natives_file =
+      OpenV8File(kNativesFileName, &files_out->natives_region);
+  files_out->natives_fd.reset(natives_file.TakePlatformFile());
+  base::File snapshot_file =
+      OpenV8File(kSnapshotFileName, &files_out->snapshot_region);
+  files_out->snapshot_fd.reset(snapshot_file.TakePlatformFile());
+}
+#endif  // defined(OS_POSIX)
+#endif  // defined(V8_USE_EXTERNAL_STARTUP_DATA)
 
 // static
 void V8Initializer::Initialize(gin::IsolateHolder::ScriptMode mode) {