Create blobs from Disk Cache entries.

net/base/upload_disk_cache_entry_element_reader.cc

+// Copyright 2015 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 "net/base/upload_disk_cache_entry_element_reader.h"
+
+#include "net/base/io_buffer.h"
+#include "net/base/net_errors.h"
+#include "net/disk_cache/disk_cache.h"
+
+namespace net {
+
+UploadDiskCacheEntryElementReader::UploadDiskCacheEntryElementReader(
+    disk_cache::Entry* disk_cache_entry,
+    int disk_cache_stream_index,
+    int range_offset,
+    int range_length)
+    : disk_cache_entry_(disk_cache_entry),
+      disk_cache_stream_index_(disk_cache_stream_index),
+      range_offset_(range_offset),
+      range_length_(range_length),
+      offset_(range_offset_),
+      weak_factory_(this) {
+  DCHECK_LE(range_offset_ + range_length,
+            disk_cache_entry_->GetDataSize(disk_cache_stream_index_));
+}
+
+UploadDiskCacheEntryElementReader::~UploadDiskCacheEntryElementReader() {
+}
+
+const UploadDiskCacheEntryElementReader*
+UploadDiskCacheEntryElementReader::AsDiskCacheEntryReader() const {
+  return this;
+}
+
+int UploadDiskCacheEntryElementReader::Init(
+    const CompletionCallback& callback) {
+  offset_ = range_offset_;
+  return OK;
+}
+
+uint64_t UploadDiskCacheEntryElementReader::GetContentLength() const {
+  return range_length_;
+}
+
+uint64_t UploadDiskCacheEntryElementReader::BytesRemaining() const {
+  return range_length_ + range_offset_ - offset_;

[michaeln, 2015/06/15 22:17:24]

nit: the math in here might be more readable in terms of 'amount_read'?

[gavinp, 2015/06/16 16:07:48]

Done.

+}
+
+bool UploadDiskCacheEntryElementReader::IsInMemory() const {
+  return false;
+}
+
+int UploadDiskCacheEntryElementReader::Read(
+    IOBuffer* buf,
+    int buf_length,
+    const CompletionCallback& callback) {
+  const int bytes_to_read =
+      std::min(buf_length, static_cast<int>(BytesRemaining()));
+
+  CompletionCallback new_callback =
+      base::Bind(&UploadDiskCacheEntryElementReader::OnReadCompleted,
+                 weak_factory_.GetWeakPtr(), callback);
+
+  const int result = disk_cache_entry_->ReadData(

[michaeln, 2015/06/15 22:17:24]

Calling ReadData() with zero bytes_to_read is ok, just checking.

[gavinp, 2015/06/16 16:07:48]

I thought so, and I just double checked all three backends, it's fine. There's
even unit tests on it.

+      disk_cache_stream_index_, offset_, buf, bytes_to_read, new_callback);
+  if (result == ERR_IO_PENDING)
+    return ERR_IO_PENDING;
+  if (result > 0)
+    offset_ += result;
+  return result;
+}
+
+void UploadDiskCacheEntryElementReader::OnReadCompleted(
+    const CompletionCallback& callback,
+    int result) {
+  if (result > 0)
+    offset_ += result;
+  callback.Run(result);
+}
+
+}  // namespace net