Create blobs from Disk Cache entries.

storage/browser/blob/blob_url_request_job.cc

Index: storage/browser/blob/blob_url_request_job.cc
diff --git a/storage/browser/blob/blob_url_request_job.cc b/storage/browser/blob/blob_url_request_job.cc
index 26607cd3e5c5db4b7cca2b66b0b69ec1883a3857..bbf9504b3bcf8d74e7075380505237e140208cf9 100644
--- a/storage/browser/blob/blob_url_request_job.cc
+++ b/storage/browser/blob/blob_url_request_job.cc
@@ -22,6 +22,7 @@
 #include "base/trace_event/trace_event.h"
 #include "net/base/io_buffer.h"
 #include "net/base/net_errors.h"
+#include "net/disk_cache/disk_cache.h"
 #include "net/http/http_request_headers.h"
 #include "net/http/http_response_headers.h"
 #include "net/http/http_response_info.h"
@@ -356,6 +357,8 @@ bool BlobURLRequestJob::ReadItem() {
   const BlobDataItem& item = *items.at(current_item_index_);
   if (item.type() == DataElement::TYPE_BYTES)
     return ReadBytesItem(item, bytes_to_read);
+  if (item.type() == DataElement::TYPE_DISK_CACHE_ENTRY)
+    return ReadDiskCacheEntryItem(item, bytes_to_read);
   if (!IsFileType(item.type())) {
     NOTREACHED();
     return false;
@@ -468,6 +471,49 @@ void BlobURLRequestJob::DeleteCurrentFileReader() {
   }
 }
 
+bool BlobURLRequestJob::ReadDiskCacheEntryItem(const BlobDataItem& item,
+                                               int bytes_to_read) {
+  DCHECK_GE(read_buf_->BytesRemaining(), bytes_to_read);
+
+  const int result = item.disk_cache_entry()->ReadData(
+      item.disk_cache_stream_index(), current_item_offset_, read_buf_.get(),
+      bytes_to_read, base::Bind(&BlobURLRequestJob::DidReadDiskCacheEntry,
+                                base::Unretained(this)));

[michaeln, 2015/06/12 23:43:06]

2 questions:

1) How is base::Unretained here safe? I don't think it is.

It's safe in ReadFileItem() because when this class is destructed the
FileStreamReader is deleted so that completion callback won't be called.

In this case, |item| is refcounted and outlives this job. And Entry's are
supposed to invoke the completion callback even after being closed.

WeakPtr?

2) Is it ok to have two ReadData calls pending against the same Entry instance.
Two different jobs could be running at the same time. Pretty sure its ok, but
just checking.

+  if (result >= 0) {
+    // Data is immediately available.
+    if (GetStatus().is_io_pending())
+      DidReadDiskCacheEntry(result);
+    else
+      AdvanceBytesRead(result);
+    return true;
+  }
+  if (result == net::ERR_IO_PENDING)
+    SetStatus(net::URLRequestStatus(net::URLRequestStatus::IO_PENDING, 0));
+  else
+    NotifyFailure(result);
+  return false;
+}
+
+void BlobURLRequestJob::DidReadDiskCacheEntry(int result) {
+  if (result <= 0) {
+    NotifyFailure(net::ERR_FAILED);
+    return;
+  }
+  SetStatus(net::URLRequestStatus());
+
+  AdvanceBytesRead(result);
+
+  if (!read_buf_->BytesRemaining()) {
+    int bytes_read = BytesReadCompleted();
+    NotifyReadComplete(bytes_read);
+    return;
+  }
+
+  int bytes_read = 0;
+  if (ReadLoop(&bytes_read))
+    NotifyReadComplete(bytes_read);
+}
+
 int BlobURLRequestJob::BytesReadCompleted() {
   int bytes_read = read_buf_->BytesConsumed();
   read_buf_ = NULL;