[BlobAsync] Disk support for blob storage

content/browser/blob_storage/blob_dispatcher_host.cc

Index: content/browser/blob_storage/blob_dispatcher_host.cc
diff --git a/content/browser/blob_storage/blob_dispatcher_host.cc b/content/browser/blob_storage/blob_dispatcher_host.cc
index 2c43055a5ecf3c7b9ff45cb2269bbfb5910aed77..54c86dae6cfb47316c42e5ee321beebecf66bf54 100644
--- a/content/browser/blob_storage/blob_dispatcher_host.cc
+++ b/content/browser/blob_storage/blob_dispatcher_host.cc
@@ -12,6 +12,7 @@
 #include "content/browser/blob_storage/chrome_blob_storage_context.h"
 #include "content/common/fileapi/webblob_messages.h"
 #include "ipc/ipc_platform_file.h"
+#include "storage/browser/blob/blob_data_handle.h"
 #include "storage/browser/blob/blob_storage_context.h"
 #include "storage/browser/blob/blob_transport_result.h"
 #include "storage/common/blob_storage/blob_item_bytes_request.h"
@@ -54,8 +55,7 @@ void BlobDispatcherHost::OnChannelClosing() {
 bool BlobDispatcherHost::OnMessageReceived(const IPC::Message& message) {
   bool handled = true;
   IPC_BEGIN_MESSAGE_MAP(BlobDispatcherHost, message)
-    IPC_MESSAGE_HANDLER(BlobStorageMsg_RegisterBlobUUID, OnRegisterBlobUUID)
-    IPC_MESSAGE_HANDLER(BlobStorageMsg_StartBuildingBlob, OnStartBuildingBlob)
+    IPC_MESSAGE_HANDLER(BlobStorageMsg_RegisterBlob, OnRegisterBlob)
     IPC_MESSAGE_HANDLER(BlobStorageMsg_MemoryItemResponse, OnMemoryItemResponse)
     IPC_MESSAGE_HANDLER(BlobStorageMsg_CancelBuildingBlob, OnCancelBuildingBlob)
     IPC_MESSAGE_HANDLER(BlobHostMsg_IncrementRefCount, OnIncrementBlobRefCount)
@@ -67,11 +67,11 @@ bool BlobDispatcherHost::OnMessageReceived(const IPC::Message& message) {
   return handled;
 }
 
-void BlobDispatcherHost::OnRegisterBlobUUID(
+void BlobDispatcherHost::OnRegisterBlob(
     const std::string& uuid,
     const std::string& content_type,
     const std::string& content_disposition,
-    const std::set<std::string>& referenced_blob_uuids) {
+    const std::vector<storage::DataElement>& descriptions) {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
   BlobStorageContext* context = this->context();
   if (uuid.empty() || context->registry().HasEntry(uuid) ||
@@ -80,67 +80,19 @@ void BlobDispatcherHost::OnRegisterBlobUUID(
     return;
   }
   blobs_inuse_map_[uuid] = 1;
-  BlobTransportResult result = async_builder_.RegisterBlobUUID(
-      uuid, content_type, content_disposition, referenced_blob_uuids, context);
-  switch (result) {
-    case BlobTransportResult::BAD_IPC:
-      blobs_inuse_map_.erase(uuid);
-      bad_message::ReceivedBadMessage(this,
-                                      bad_message::BDH_CONSTRUCTION_FAILED);
-      break;
-    case BlobTransportResult::CANCEL_REFERENCED_BLOB_BROKEN:
-      // The async builder builds the blob as broken, and we just need to send
-      // the cancel message back to the renderer.
-      Send(new BlobStorageMsg_CancelBuildingBlob(
-          uuid, IPCBlobCreationCancelCode::REFERENCED_BLOB_BROKEN));
-      break;
-    case BlobTransportResult::DONE:
-      break;
-    case BlobTransportResult::CANCEL_MEMORY_FULL:
-    case BlobTransportResult::CANCEL_FILE_ERROR:
-    case BlobTransportResult::CANCEL_UNKNOWN:
-    case BlobTransportResult::PENDING_RESPONSES:
-      NOTREACHED();
-      break;
-  }
-}
-
-void BlobDispatcherHost::OnStartBuildingBlob(
-    const std::string& uuid,
-    const std::vector<storage::DataElement>& descriptions) {
-  DCHECK_CURRENTLY_ON(BrowserThread::IO);
-  if (uuid.empty()) {
-    SendIPCResponse(uuid, BlobTransportResult::BAD_IPC);
-    return;
-  }
-  BlobStorageContext* context = this->context();
-  const BlobStorageRegistry::Entry* entry = context->registry().GetEntry(uuid);
-  if (!entry || entry->state == BlobStorageRegistry::BlobState::BROKEN) {
-    // We ignore messages for blobs that don't exist to handle the case where
-    // the renderer de-refs a blob that we're still constructing, and there are
-    // no references to that blob. We ignore broken as well, in the case where
-    // we decided to break a blob after RegisterBlobUUID is called.
-    // Second, if the last dereference of the blob happened on a different host,
-    // then we still haven't gotten rid of the 'building' state in the original
-    // host. So we call cancel, and send the message just in case that happens.
-    if (async_builder_.IsBeingBuilt(uuid)) {
-      async_builder_.CancelBuildingBlob(
-          uuid, IPCBlobCreationCancelCode::BLOB_DEREFERENCED_WHILE_BUILDING,
-          context);
-      Send(new BlobStorageMsg_CancelBuildingBlob(
-          uuid, IPCBlobCreationCancelCode::BLOB_DEREFERENCED_WHILE_BUILDING));
-    }
-    return;
-  }
-  if (!async_builder_.IsBeingBuilt(uuid)) {
-    SendIPCResponse(uuid, BlobTransportResult::BAD_IPC);
-    return;
-  }
-  // |this| owns async_builder_ so using base::Unretained(this) is safe.
-  BlobTransportResult result = async_builder_.StartBuildingBlob(
-      uuid, descriptions, context->memory_available(), context,
+  std::unique_ptr<storage::BlobDataHandle> handle;

[michaeln, 2016/07/07 20:05:20]

This local variable isn't used in any obvious way, is it and the out param
really needed?

+  BlobTransportResult result = async_builder_.RegisterBlob(
+      uuid, content_type, content_disposition, descriptions, context, &handle,
       base::Bind(&BlobDispatcherHost::SendMemoryRequest, base::Unretained(this),
-                 uuid));
+                 uuid),
+      base::Bind(&BlobDispatcherHost::CancelBlob, base::Unretained(this), uuid),
+      base::Bind(&BlobDispatcherHost::SendIPCResponse, base::Unretained(this),
+                 uuid, BlobTransportResult::DONE));
+  if (result == BlobTransportResult::BAD_IPC) {
+    blobs_inuse_map_.erase(uuid);

[michaeln, 2016/07/07 20:05:20]

you can probably get rid of some branching logic here. maybe call
bad_message::ReceivedBadMessage directly and return here instead of doing
unnecessary book keeping. 

+  } else {
+    context->IncrementBlobRefCount(uuid);

[michaeln, 2016/07/07 20:05:20]

Where is the balancing call to Decrement? Oh, this adds a ref that the deletion
of the handle will decrement, so the newly registered blob will have a refcount
of 1.

It might be good to encapsulate the responsibility for 'creating it with a
refcount of one' into the builder class and to not have the 'handle' as an out
param.

+  }
   SendIPCResponse(uuid, result);
 }
 
@@ -309,8 +261,9 @@ void BlobDispatcherHost::SendMemoryRequest(
     std::unique_ptr<std::vector<base::File>> files) {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
   std::vector<IPC::PlatformFileForTransit> file_handles;
-  // TODO(dmurph): Support file-backed blob transportation.
-  DCHECK(files->empty());
+  for (base::File& file : *files) {
+    file_handles.push_back(IPC::TakePlatformFileForTransit(std::move(file)));
+  }
   Send(new BlobStorageMsg_RequestMemoryItem(uuid, *requests, *memory_handles,
                                             file_handles));
 }
@@ -347,6 +300,11 @@ void BlobDispatcherHost::SendIPCResponse(const std::string& uuid,
   NOTREACHED();
 }
 
+void BlobDispatcherHost::CancelBlob(const std::string& uuid,

[michaeln, 2016/07/07 20:05:20]

maybe name this SendCancelBlob in keeping with how SendMemoryRequest and
SendIPCResponse are named

+                                    IPCBlobCreationCancelCode reason) {
+  Send(new BlobStorageMsg_CancelBuildingBlob(uuid, reason));
+}
+
 bool BlobDispatcherHost::IsInUseInHost(const std::string& uuid) {
   return blobs_inuse_map_.find(uuid) != blobs_inuse_map_.end();
 }