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      1 // Copyright 2014 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #ifndef MOJO_BINDINGS_JS_DRAIN_DATA_H_
      6 #define MOJO_BINDINGS_JS_DRAIN_DATA_H_
      7 
      8 #include "base/memory/scoped_vector.h"
      9 #include "gin/runner.h"
     10 #include "mojo/public/c/environment/async_waiter.h"
     11 #include "mojo/public/cpp/system/core.h"
     12 #include "v8/include/v8.h"
     13 
     14 namespace mojo {
     15 namespace js {
     16 
     17 // This class is the implementation of the Mojo JavaScript core module's
     18 // drainData() method. It is not intended to be used directly. The caller
     19 // allocates a DrainData on the heap and returns GetPromise() to JS. The
     20 // implementation deletes itself after reading as much data as possible
     21 // and rejecting or resolving the Promise.
     22 
     23 class DrainData {
     24  public:
     25   // Starts waiting for data on the specified data pipe consumer handle.
     26   // See WaitForData(). The constructor does not block.
     27   DrainData(v8::Isolate* isolate, mojo::Handle handle);
     28 
     29   // Returns a Promise that will be settled when no more data can be read.
     30   // Should be called just once on a newly allocated DrainData object.
     31   v8::Handle<v8::Value> GetPromise();
     32 
     33  private:
     34   ~DrainData();
     35 
     36   // Registers an "async waiter" that calls DataReady() via WaitCompleted().
     37   void WaitForData();
     38   static void WaitCompleted(void* self, MojoResult result) {
     39     static_cast<DrainData*>(self)->DataReady(result);
     40   }
     41 
     42   // Use ReadData() to read whatever is availble now on handle_ and save
     43   // it in data_buffers_.
     44   void DataReady(MojoResult result);
     45   MojoResult ReadData();
     46 
     47   // When the remote data pipe handle is closed, or an error occurs, deliver
     48   // all of the buffered data to the JS Promise and then delete this.
     49   void DeliverData(MojoResult result);
     50 
     51   typedef std::vector<char> DataBuffer;
     52 
     53   v8::Isolate* isolate_;
     54   ScopedDataPipeConsumerHandle handle_;
     55   MojoAsyncWaitID wait_id_;
     56   base::WeakPtr<gin::Runner> runner_;
     57   v8::UniquePersistent<v8::Promise::Resolver> resolver_;
     58   ScopedVector<DataBuffer> data_buffers_;
     59 };
     60 
     61 }  // namespace js
     62 }  // namespace mojo
     63 
     64 #endif  // MOJO_BINDINGS_JS_DRAIN_DATA_H_
     65