[mojo] Ports EDK

mojo/edk/system/shared_buffer_dispatcher.h

 // Copyright 2014 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.
 
 #ifndef MOJO_EDK_SYSTEM_SHARED_BUFFER_DISPATCHER_H_
 #define MOJO_EDK_SYSTEM_SHARED_BUFFER_DISPATCHER_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <utility>
 
+#include "base/macros.h"
+#include "mojo/edk/embedder/platform_handle_vector.h"
 #include "mojo/edk/embedder/platform_shared_buffer.h"
-#include "mojo/edk/system/simple_dispatcher.h"
+#include "mojo/edk/embedder/scoped_platform_handle.h"
+#include "mojo/edk/system/dispatcher.h"
 #include "mojo/edk/system/system_impl_export.h"
-#include "mojo/public/cpp/system/macros.h"
 
 namespace mojo {
 
 namespace edk {
 class PlatformSupport;
 
-// TODO(vtl): We derive from SimpleDispatcher, even though we don't currently
-// have anything that's waitable. I want to add a "transferrable" wait flag
-// (which would entail overriding |GetHandleSignalsStateImplNoLock()|, etc.).
-class MOJO_SYSTEM_IMPL_EXPORT SharedBufferDispatcher final
-    : public SimpleDispatcher {
+class MOJO_SYSTEM_IMPL_EXPORT SharedBufferDispatcher final : public Dispatcher {
  public:
   // The default options to use for |MojoCreateSharedBuffer()|. (Real uses
   // should obtain this via |ValidateCreateOptions()| with a null |in_options|;
   // this is exposed directly for testing convenience.)
   static const MojoCreateSharedBufferOptions kDefaultCreateOptions;
 
   // Validates and/or sets default options for |MojoCreateSharedBufferOptions|.
   // If non-null, |in_options| must point to a struct of at least
   // |in_options->struct_size| bytes. |out_options| must point to a (current)
   // |MojoCreateSharedBufferOptions| and will be entirely overwritten on success
   // (it may be partly overwritten on failure).
   static MojoResult ValidateCreateOptions(
       const MojoCreateSharedBufferOptions* in_options,
       MojoCreateSharedBufferOptions* out_options);
 
   // Static factory method: |validated_options| must be validated (obviously).
   // On failure, |*result| will be left as-is.
   // TODO(vtl): This should probably be made to return a scoped_refptr and have
   // a MojoResult out parameter instead.
   static MojoResult Create(
       PlatformSupport* platform_support,
       const MojoCreateSharedBufferOptions& validated_options,
       uint64_t num_bytes,
       scoped_refptr<SharedBufferDispatcher>* result);
 
-  // |Dispatcher| public methods:
+  // The "opposite" of SerializeAndClose(). Called by Dispatcher::Deserialize().
+  static scoped_refptr<SharedBufferDispatcher> Deserialize(
+      const void* bytes,
+      size_t num_bytes,
+      const ports::PortName* ports,
+      size_t num_ports,
+      PlatformHandle* platform_handles,
+      size_t num_platform_handles);
+
+  // Dispatcher:
   Type GetType() const override;
-
-  // The "opposite" of |SerializeAndClose()|. (Typically this is called by
-  // |Dispatcher::Deserialize()|.)
-  static scoped_refptr<SharedBufferDispatcher> Deserialize(
-      const void* source,
-      size_t size,
-      PlatformHandleVector* platform_handles);
+  MojoResult Close() override;
+  MojoResult DuplicateBufferHandle(
+      const MojoDuplicateBufferHandleOptions* options,
+      scoped_refptr<Dispatcher>* new_dispatcher) override;
+  MojoResult MapBuffer(
+      uint64_t offset,
+      uint64_t num_bytes,
+      MojoMapBufferFlags flags,
+      scoped_ptr<PlatformSharedBufferMapping>* mapping) override;
+  void StartSerialize(uint32_t* num_bytes,
+                      uint32_t* num_ports,
+                      uint32_t* num_platform_handles) override;
+  bool EndSerialize(void* destination,
+                    ports::PortName* ports,
+                    PlatformHandle* handles) override;
+  bool BeginTransit() override;
+  void CompleteTransitAndClose() override;
+  void CancelTransit() override;
 
  private:
   static scoped_refptr<SharedBufferDispatcher> CreateInternal(
       scoped_refptr<PlatformSharedBuffer> shared_buffer) {
     return make_scoped_refptr(
         new SharedBufferDispatcher(std::move(shared_buffer)));
   }
 
   explicit SharedBufferDispatcher(
       scoped_refptr<PlatformSharedBuffer> shared_buffer);
   ~SharedBufferDispatcher() override;
 
   // Validates and/or sets default options for
   // |MojoDuplicateBufferHandleOptions|. If non-null, |in_options| must point to
   // a struct of at least |in_options->struct_size| bytes. |out_options| must
   // point to a (current) |MojoDuplicateBufferHandleOptions| and will be
   // entirely overwritten on success (it may be partly overwritten on failure).
   static MojoResult ValidateDuplicateOptions(
       const MojoDuplicateBufferHandleOptions* in_options,
       MojoDuplicateBufferHandleOptions* out_options);
 
-  // |Dispatcher| protected methods:
-  void CloseImplNoLock() override;
-  scoped_refptr<Dispatcher> CreateEquivalentDispatcherAndCloseImplNoLock()
-      override;
-  MojoResult DuplicateBufferHandleImplNoLock(
-      const MojoDuplicateBufferHandleOptions* options,
-      scoped_refptr<Dispatcher>* new_dispatcher) override;
-  MojoResult MapBufferImplNoLock(
-      uint64_t offset,
-      uint64_t num_bytes,
-      MojoMapBufferFlags flags,
-      scoped_ptr<PlatformSharedBufferMapping>* mapping) override;
-  void StartSerializeImplNoLock(size_t* max_size,
-                                size_t* max_platform_handles) override;
-  bool EndSerializeAndCloseImplNoLock(
-      void* destination,
-      size_t* actual_size,
-      PlatformHandleVector* platform_handles) override;
+  // Guards access to |shared_buffer_|.
+  base::Lock lock_;
+
+  bool in_transit_ = false;
+
+  // We keep a copy of the buffer's platform handle during transit so we can
+  // close it if something goes wrong.
+  ScopedPlatformHandle handle_for_transit_;

[Anand Mistry (off Chromium), 2016/01/28 02:26:25]

Instead of keeping track, why not just pass ownership of the duplicated handle
and let the caller discard it if something goes wrong?

 
   scoped_refptr<PlatformSharedBuffer> shared_buffer_;
 
-  MOJO_DISALLOW_COPY_AND_ASSIGN(SharedBufferDispatcher);
+  DISALLOW_COPY_AND_ASSIGN(SharedBufferDispatcher);
 };
 
 }  // namespace edk
 }  // namespace mojo
 
 #endif  // MOJO_EDK_SYSTEM_SHARED_BUFFER_DISPATCHER_H_