net: Make UploadDataStream::Init() asynchronous.

net/base/upload_data_stream.cc

Index: net/base/upload_data_stream.cc
diff --git a/net/base/upload_data_stream.cc b/net/base/upload_data_stream.cc
index 5b2e5d30b659cbf7410da85b41898ee604819fb4..19118b603b4185a0b748701f34bf9c2f631a1d2f 100644
--- a/net/base/upload_data_stream.cc
+++ b/net/base/upload_data_stream.cc
@@ -7,55 +7,91 @@
 #include "base/file_util.h"
 #include "base/logging.h"
 #include "base/threading/thread_restrictions.h"
+#include "base/threading/worker_pool.h"
+#include "base/tracked_objects.h"
 #include "net/base/file_stream.h"
 #include "net/base/io_buffer.h"
 #include "net/base/net_errors.h"
 
 namespace net {
 
-bool UploadDataStream::merge_chunks_ = true;
-
-UploadDataStream::UploadDataStream(UploadData* upload_data)
-    : upload_data_(upload_data),
-      element_index_(0),
-      element_offset_(0),
-      element_file_bytes_remaining_(0),
-      total_size_(0),
-      current_position_(0),
-      initialized_successfully_(false) {
-}
-
-UploadDataStream::~UploadDataStream() {
-}
-
-int UploadDataStream::Init() {
-  DCHECK(!initialized_successfully_);
-
-  {
-    base::ThreadRestrictions::ScopedAllowIO allow_io;
-    total_size_ = upload_data_->GetContentLengthSync();
-  }
+namespace {
 
+// Checks if any file in |upload_file| is modified since we initially
+// observed. Stores ERR_UPLOAD_FILE_CHANGED in |result| if such a
+// modification is detected. Otherwise, stores OK in |result|.
+void CheckModifiedFiles(scoped_refptr<UploadData> upload_data, int* result) {
   // If the underlying file has been changed and the expected file
   // modification time is set, treat it as error. Note that the expected
   // modification time from WebKit is based on time_t precision. So we
   // have to convert both to time_t to compare. This check is used for
   // sliced files.
-  const std::vector<UploadData::Element>& elements = *upload_data_->elements();
+  const std::vector<UploadData::Element>& elements = *upload_data->elements();
   for (size_t i = 0; i < elements.size(); ++i) {
     const UploadData::Element& element = elements[i];
     if (element.type() == UploadData::TYPE_FILE &&
         !element.expected_file_modification_time().is_null()) {
-      // Temporarily allow until fix: http://crbug.com/72001.
-      base::ThreadRestrictions::ScopedAllowIO allow_io;
       base::PlatformFileInfo info;
       if (file_util::GetFileInfo(element.file_path(), &info) &&
           element.expected_file_modification_time().ToTimeT() !=
           info.last_modified.ToTimeT()) {
-        return ERR_UPLOAD_FILE_CHANGED;
+        *result = ERR_UPLOAD_FILE_CHANGED;
+        return;
       }
     }
   }
+  *result = OK;
+  return;
+}
+
+}  // namespace
+
+bool UploadDataStream::merge_chunks_ = true;
+
+UploadDataStream::UploadDataStream(UploadData* upload_data)
+    : upload_data_(upload_data),
+      element_index_(0),
+      element_offset_(0),
+      element_file_bytes_remaining_(0),
+      total_size_(0),
+      current_position_(0),
+      initialized_successfully_(false),
+      weak_ptr_factory_(ALLOW_THIS_IN_INITIALIZER_LIST(this)) {
+}
+
+UploadDataStream::~UploadDataStream() {
+}
+
+int UploadDataStream::Init(const CompletionCallback& on_completion) {
+  DCHECK(!initialized_successfully_);
+  DCHECK(user_callback_.is_null());
+
+  // Fast path. Initialize synchronously if the data is in memory.
+  if (upload_data_->IsInMemory())
+    return InitSync();
+
+  // The asynchronous initialization is performed in the following steps:
+  // 1. GetContentLength() computes the content length in the background.
+  // 2. OnGetContentLengthComplete() is called once it's done.
+  // 3. CheckModifiedFiles() checks the modified files in the background.
+  // 4. OnCheckModifiedFilesComplete() is called once it's done.
+  // 5. user_callback_ is run with the initialization result.
+  user_callback_ = on_completion;
+  upload_data_->GetContentLength(
+      base::Bind(&UploadDataStream::OnGetContentLengthComplete,
+                 weak_ptr_factory_.GetWeakPtr()));
+  return ERR_IO_PENDING;
+}
+
+int UploadDataStream::InitSync() {
+  DCHECK(!initialized_successfully_);
+
+  total_size_ = upload_data_->GetContentLengthSync();
+
+  int result = OK;
+  CheckModifiedFiles(upload_data_, &result);
+  if (result != OK)
+    return result;
 
   initialized_successfully_ = true;
   return OK;
@@ -164,6 +200,31 @@ void UploadDataStream::AdvanceToNextElement() {
   }
 }
 
+void UploadDataStream::OnGetContentLengthComplete(uint64 content_length) {
+  total_size_ = content_length;
+  int* result = new int(OK);
+  const bool posted = base::WorkerPool::PostTaskAndReply(
+      FROM_HERE,
+      base::Bind(&CheckModifiedFiles, upload_data_, result),
+      base::Bind(&UploadDataStream::OnCheckModifiedFilesComplete,
+                 weak_ptr_factory_.GetWeakPtr(),
+                 base::Owned(result)),
+      true /* task_is_slow */);
+  DCHECK(posted);
+}
+
+void UploadDataStream::OnCheckModifiedFilesComplete(int* result) {
+  if (*result == OK)
+    initialized_successfully_ = true;
+
+  // Tell the caller of Init() that the initialization is done. Run() may
+  // triger other asynchronous operations so user_callback_ is reset before
+  // running it.
+  CompletionCallback copied_user_callback = user_callback_;
+  user_callback_.Reset();
+  copied_user_callback.Run(*result);
+}
+
 bool UploadDataStream::IsEOF() const {
   const std::vector<UploadData::Element>& elements = *upload_data_->elements();