Set error on WebDataConsumerHandle while loading body.

content/child/shared_memory_data_consumer_handle.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 "content/child/shared_memory_data_consumer_handle.h"
 
 #include <algorithm>
 #include <deque>
 
 #include "base/bind.h"
@@ skipping 35 matching lines @@
 
 using Result = blink::WebDataConsumerHandle::Result;
 
 class SharedMemoryDataConsumerHandle::Context final
     : public base::RefCountedThreadSafe<Context> {
  public:
   Context()
       : result_(Ok),
         first_offset_(0),
         client_(nullptr),
-        is_handle_active_(true) {}
+        is_handle_active_(true),
+        is_two_phase_read_in_progress_(false) {}
 
   bool IsEmpty() const { return queue_.empty(); }
   void ClearIfNecessary() {
     if (!is_handle_locked() && !is_handle_active()) {
       // No one is interested in the contents.
       Clear();
     }
   }
+  void ClearQueue() {
+    for (auto& data : queue_) {
+      delete data;
+    }
+    queue_.clear();
+    first_offset_ = 0;
+  }
   RequestPeer::ThreadSafeReceivedData* Top() { return queue_.front(); }
   void Push(scoped_ptr<RequestPeer::ThreadSafeReceivedData> data) {
     queue_.push_back(data.release());
   }
   size_t first_offset() const { return first_offset_; }
   Result result() const { return result_; }
   void set_result(Result r) { result_ = r; }
   void AcquireReaderLock(Client* client) {
     DCHECK(!notification_task_runner_);
     DCHECK(!client_);
     notification_task_runner_ = base::MessageLoop::current()->task_runner();
     client_ = client;
     if (client && !(IsEmpty() && result() == Ok)) {
       // We cannot notify synchronously because the user doesn't have the reader
       // yet.
       notification_task_runner_->PostTask(
           FROM_HERE, base::Bind(&Context::NotifyInternal, this, false));
     }
   }
   void ReleaseReaderLock() {
     DCHECK(notification_task_runner_);
     notification_task_runner_ = nullptr;
     client_ = nullptr;
   }
+  void PostNotify() {
+    auto runner = notification_task_runner_;
+    if (!runner)
+      return;
+    // We don't re-post the task when the runner changes while waiting for
+    // this task because in this case a new reader is obtained and
+    // notification is already done at the reader creation time if necessary.
+    runner->PostTask(FROM_HERE,
+                     base::Bind(&Context::NotifyInternal, this, false));
+  }
   void Notify() { NotifyInternal(true); }
   bool is_handle_locked() const { return notification_task_runner_; }
   bool IsReaderBoundToCurrentThread() const {
     return notification_task_runner_ &&
            notification_task_runner_->BelongsToCurrentThread();
   }
   bool is_handle_active() const { return is_handle_active_; }
   void set_is_handle_active(bool b) { is_handle_active_ = b; }
   void Consume(size_t s) {
     first_offset_ += s;
     auto top = Top();
     if (static_cast<size_t>(top->length()) <= first_offset_) {
       delete top;
       queue_.pop_front();
       first_offset_ = 0;
     }
   }
+  bool is_two_phase_read_in_progress() const {
+    return is_two_phase_read_in_progress_;
+  }
+  void set_is_two_phase_read_in_progress(bool b) {
+    is_two_phase_read_in_progress_ = b;
+  }
   base::Lock& lock() { return lock_; }
 
  private:
   void NotifyInternal(bool repost) {
     // Note that this function is not protected by |lock_|.
 
     auto runner = notification_task_runner_;
     if (!runner)
       return;
 
@@ skipping 31 matching lines @@
   // |result_| stores the ultimate state of this handle if it has. Otherwise,
   // |Ok| is set.
   Result result_;
   // TODO(yhirano): Use std::deque<scoped_ptr<ThreadSafeReceivedData>>
   // once it is allowed.
   std::deque<RequestPeer::ThreadSafeReceivedData*> queue_;
   size_t first_offset_;
   Client* client_;
   scoped_refptr<base::SingleThreadTaskRunner> notification_task_runner_;
   bool is_handle_active_;
+  bool is_two_phase_read_in_progress_;
 
   DISALLOW_COPY_AND_ASSIGN(Context);
 };
 
 SharedMemoryDataConsumerHandle::Writer::Writer(
     const scoped_refptr<Context>& context,
     BackpressureMode mode)
     : context_(context), mode_(mode) {
 }
 
@@ skipping 20 matching lines @@
     scoped_ptr<RequestPeer::ThreadSafeReceivedData> data_to_pass;
     if (mode_ == kApplyBackpressure) {
       data_to_pass =
           make_scoped_ptr(new DelegateThreadSafeReceivedData(data.Pass()));
     } else {
       data_to_pass = make_scoped_ptr(new FixedReceivedData(data.get()));
     }
     context_->Push(data_to_pass.Pass());
   }
 
-  if (needs_notification)
+  if (needs_notification) {
+    // We CAN issue the notification synchronously if the associated reader
+    // lives in this thread, because this function cannot be called in the
+    // client's callback.
     context_->Notify();
+  }
 }
 
 void SharedMemoryDataConsumerHandle::Writer::Close() {
   bool needs_notification = false;
 
   {
     base::AutoLock lock(context_->lock());
     if (context_->result() == Ok) {
       context_->set_result(Done);
       needs_notification = context_->IsEmpty();
     }
   }
-  if (needs_notification)
-    context_->Notify();
+  if (needs_notification) {
+    // We cannot issue the notification synchronously because this function can
+    // be called in the client's callback.
+    context_->PostNotify();
+  }
+}
+
+void SharedMemoryDataConsumerHandle::Writer::Fail() {
+  bool needs_notification = false;
+  {
+    base::AutoLock lock(context_->lock());
+    if (context_->result() == Ok) {
+      // TODO(yhirano): Use an appropriate error code other than
+      // UnexpectedError.
+      context_->set_result(UnexpectedError);
+
+      if (context_->is_two_phase_read_in_progress()) {
+        // If we are in two-phase read session, we cannot discard the data. We
+        // will clear the queue at the end of the session.
+      } else {
+        context_->ClearQueue();
+      }
+
+      needs_notification = true;
+    }
+  }
+  if (needs_notification) {
+    // We cannot issue the notification synchronously because this function can
+    // be called in the client's callback.
+    context_->PostNotify();
+  }
 }
 
 SharedMemoryDataConsumerHandle::ReaderImpl::ReaderImpl(
     scoped_refptr<Context> context,
     Client* client)
     : context_(context) {
   base::AutoLock lock(context_->lock());
   DCHECK(!context_->is_handle_locked());
   context_->AcquireReaderLock(client);
 }
 
 SharedMemoryDataConsumerHandle::ReaderImpl::~ReaderImpl() {
   base::AutoLock lock(context_->lock());
   context_->ReleaseReaderLock();
   context_->ClearIfNecessary();
 }
 
 Result SharedMemoryDataConsumerHandle::ReaderImpl::read(
     void* data,
     size_t size,
     Flags flags,
     size_t* read_size_to_return) {
   base::AutoLock lock(context_->lock());
 
   size_t total_read_size = 0;
   *read_size_to_return = 0;
+
+  if (context_->result() == Ok && context_->is_two_phase_read_in_progress())
+    context_->set_result(UnexpectedError);
+
   if (context_->result() != Ok && context_->result() != Done)
     return context_->result();
 
   while (!context_->IsEmpty() && total_read_size < size) {
     const auto& top = context_->Top();
     size_t readable = top->length() - context_->first_offset();
     size_t writable = size - total_read_size;
     size_t read_size = std::min(readable, writable);
     const char* begin = top->payload() + context_->first_offset();
     std::copy(begin, begin + read_size,
               static_cast<char*>(data) + total_read_size);
     total_read_size += read_size;
     context_->Consume(read_size);
   }
   *read_size_to_return = total_read_size;
   return total_read_size ? Ok : context_->result() == Done ? Done : ShouldWait;
 }
 
 Result SharedMemoryDataConsumerHandle::ReaderImpl::beginRead(
     const void** buffer,
     Flags flags,
     size_t* available) {
   *buffer = nullptr;
   *available = 0;
 
   base::AutoLock lock(context_->lock());
 
+  if (context_->result() == Ok && context_->is_two_phase_read_in_progress())
+    context_->set_result(UnexpectedError);
+
   if (context_->result() != Ok && context_->result() != Done)
     return context_->result();
 
   if (context_->IsEmpty())
     return context_->result() == Done ? Done : ShouldWait;
 
+  context_->set_is_two_phase_read_in_progress(true);
   const auto& top = context_->Top();
   *buffer = top->payload() + context_->first_offset();
   *available = top->length() - context_->first_offset();
 
   return Ok;
 }
 
 Result SharedMemoryDataConsumerHandle::ReaderImpl::endRead(size_t read_size) {
   base::AutoLock lock(context_->lock());
 
-  if (context_->IsEmpty())
+  if (!context_->is_two_phase_read_in_progress())
     return UnexpectedError;
 
-  context_->Consume(read_size);
+  context_->set_is_two_phase_read_in_progress(false);
+  if (context_->result() != Ok && context_->result() != Done) {
+    // We have an error, so we can discard the stored data.
+    context_->ClearQueue();
+  } else {
+    context_->Consume(read_size);
+  }
+
   return Ok;
 }
 
 SharedMemoryDataConsumerHandle::SharedMemoryDataConsumerHandle(
     BackpressureMode mode,
     scoped_ptr<Writer>* writer)
     : context_(new Context) {
   writer->reset(new Writer(context_, mode));
 }
 
 SharedMemoryDataConsumerHandle::~SharedMemoryDataConsumerHandle() {
   base::AutoLock lock(context_->lock());
   context_->set_is_handle_active(false);
   context_->ClearIfNecessary();
 }
 
 scoped_ptr<blink::WebDataConsumerHandle::Reader>
 SharedMemoryDataConsumerHandle::ObtainReader(Client* client) {
   return make_scoped_ptr(obtainReaderInternal(client));
 }
 
 SharedMemoryDataConsumerHandle::ReaderImpl*
 SharedMemoryDataConsumerHandle::obtainReaderInternal(Client* client) {
   return new ReaderImpl(context_, client);
 }
 
-Result SharedMemoryDataConsumerHandle::read(void* data,
-                                            size_t size,
-                                            Flags flags,
-                                            size_t* read_size_to_return) {
-  // Note this (and below similar functions) is a bit racy. We don't care about
-  // it because this is a deprecated function and will be removed shortly.
-  LockImplicitly();
-  return reader_->read(data, size, flags, read_size_to_return);
-}
-
-Result SharedMemoryDataConsumerHandle::beginRead(const void** buffer,
-                                                 Flags flags,
-                                                 size_t* available) {
-  LockImplicitly();
-  return reader_->beginRead(buffer, flags, available);
-}
-
-Result SharedMemoryDataConsumerHandle::endRead(size_t read_size) {
-  LockImplicitly();
-  return reader_->endRead(read_size);
-}
-
-void SharedMemoryDataConsumerHandle::registerClient(Client* client) {
-  UnlockImplicitly();
-  reader_ = ObtainReader(client);
-}
-
-void SharedMemoryDataConsumerHandle::unregisterClient() {
-  reader_.reset();
-}
-
-void SharedMemoryDataConsumerHandle::LockImplicitly() {
-  {
-    base::AutoLock lock(context_->lock());
-    if (reader_) {
-      DCHECK(context_->IsReaderBoundToCurrentThread());
-      return;
-    }
-  }
-  reader_ = ObtainReader(nullptr);
-}
-
-void SharedMemoryDataConsumerHandle::UnlockImplicitly() {
-  bool needs_unlock = false;
-  {
-    base::AutoLock lock(context_->lock());
-    if (reader_) {
-      DCHECK(context_->IsReaderBoundToCurrentThread());
-      needs_unlock = true;
-    }
-  }
-  if (needs_unlock) {
-    reader_.reset();
-  }
-}
-
 const char* SharedMemoryDataConsumerHandle::debugName() const {
   return "SharedMemoryDataConsumerHandle";
 }
 
 }  // namespace content