net: Make UploadDataStream::Read() 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 a62528d9bf816adacef194387cd06d21178f2fab..5b57a26b1aaa9d3a40277c3152521d515aa2e14e 100644
--- a/net/base/upload_data_stream.cc
+++ b/net/base/upload_data_stream.cc
@@ -25,7 +25,7 @@ UploadDataStream::UploadDataStream(UploadData* upload_data)
       total_size_(0),
       current_position_(0),
       initialized_successfully_(false),
-      weak_ptr_factory_(this) {
+      weak_ptr_factory_(ALLOW_THIS_IN_INITIALIZER_LIST(this)) {
   const std::vector<UploadElement>& elements = *upload_data_->elements();
   for (size_t i = 0; i < elements.size(); ++i)
     element_readers_.push_back(UploadElementReader::Create(elements[i]));
@@ -62,8 +62,26 @@ int UploadDataStream::InitSync() {
   return OK;
 }
 
-int UploadDataStream::Read(IOBuffer* buf, int buf_len) {
+int UploadDataStream::Read(IOBuffer* buf,
+                           int buf_len,
+                           const CompletionCallback& callback) {
   DCHECK(initialized_successfully_);
+  DCHECK(!callback.is_null());
+  DCHECK_GT(buf_len, 0);
+
+  // Process chunked data with ReadSync() since it requires special logic, and
+  // is always in memory.
+  if (is_chunked())
+    return ReadSync(buf, buf_len);
+
+  const bool invoked_asynchronously = false;
+  return ReadInternal(new DrainableIOBuffer(buf, buf_len),
+                      invoked_asynchronously, callback, 0);
+}
+
+int UploadDataStream::ReadSync(IOBuffer* buf, int buf_len) {
+  DCHECK(initialized_successfully_);
+  DCHECK_GT(buf_len, 0);
 
   // Initialize readers for newly appended chunks.
   if (is_chunked()) {
@@ -71,6 +89,9 @@ int UploadDataStream::Read(IOBuffer* buf, int buf_len) {
     DCHECK_LE(element_readers_.size(), elements.size());
 
     for (size_t i = element_readers_.size(); i < elements.size(); ++i) {
+      // We can initialize readers synchronously here because only bytes can be
+      // appended for chunked data. We leave |total_size_| at zero, since for
+      // chunked uploads, we may not know the total size.
       const UploadElement& element = elements[i];
       DCHECK_EQ(UploadElement::TYPE_BYTES, element.type());
       UploadElementReader* reader = UploadElementReader::Create(element);
@@ -84,8 +105,10 @@ int UploadDataStream::Read(IOBuffer* buf, int buf_len) {
   int bytes_copied = 0;
   while (bytes_copied < buf_len && element_index_ < element_readers_.size()) {
     UploadElementReader* reader = element_readers_[element_index_];
-    bytes_copied += reader->ReadSync(buf->data() + bytes_copied,
-                                     buf_len - bytes_copied);
+    scoped_refptr<DrainableIOBuffer> sub_buffer =
+        new DrainableIOBuffer(buf, buf_len);
+    sub_buffer->SetOffset(bytes_copied);
+    bytes_copied += reader->ReadSync(sub_buffer, sub_buffer->BytesRemaining());
     if (reader->BytesRemaining() == 0)
       ++element_index_;
 
@@ -179,4 +202,48 @@ void UploadDataStream::FinalizeInitialization() {
   initialized_successfully_ = true;
 }
 
+int UploadDataStream::ReadInternal(scoped_refptr<DrainableIOBuffer> buf,
+                                   bool invoked_asynchronously,
+                                   const CompletionCallback& callback,
+                                   int previous_result) {
+  DCHECK(initialized_successfully_);
+  DCHECK_GE(previous_result, 0);
+
+  // Add the last result.
+  buf->DidConsume(previous_result);
+
+  while (element_index_ < element_readers_.size()) {
+    UploadElementReader* reader = element_readers_[element_index_];
+
+    if (reader->BytesRemaining() == 0) {
+      ++element_index_;
+      continue;
+    }
+
+    if (buf->BytesRemaining() == 0)
+      break;
+
+    const int result = reader->Read(
+        buf,
+        buf->BytesRemaining(),
+        base::Bind(base::IgnoreResult(&UploadDataStream::ReadInternal),
+                   weak_ptr_factory_.GetWeakPtr(),
+                   buf,
+                   true,  // invoked_asynchronously
+                   callback));
+    if (result == ERR_IO_PENDING)
+      return ERR_IO_PENDING;
+    DCHECK_GE(result, 0);
+    buf->DidConsume(result);
+  }
+
+  const int bytes_copied = buf->BytesConsumed();
+  current_position_ += bytes_copied;
+
+  // When invoked asynchronously, callback is the only way to return the result.
+  if (invoked_asynchronously)
+    callback.Run(bytes_copied);
+  return bytes_copied;
+}
+
 }  // namespace net