258 lines
9.9 KiB
C++
258 lines
9.9 KiB
C++
// Copyright 2013 The Chromium Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#ifndef MOJO_EDK_SYSTEM_DISPATCHER_H_
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#define MOJO_EDK_SYSTEM_DISPATCHER_H_
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#include <stddef.h>
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#include <stdint.h>
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#include <memory>
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#include <ostream>
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#include <vector>
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#include "base/macros.h"
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#include "base/memory/ref_counted.h"
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#include "base/synchronization/lock.h"
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#include "mojo/edk/embedder/platform_handle.h"
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#include "mojo/edk/embedder/platform_shared_buffer.h"
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#include "mojo/edk/system/handle_signals_state.h"
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#include "mojo/edk/system/ports/name.h"
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#include "mojo/edk/system/system_impl_export.h"
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#include "mojo/edk/system/watcher.h"
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#include "mojo/public/c/system/buffer.h"
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#include "mojo/public/c/system/data_pipe.h"
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#include "mojo/public/c/system/message_pipe.h"
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#include "mojo/public/c/system/types.h"
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namespace mojo {
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namespace edk {
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class Awakable;
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class Dispatcher;
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class MessageForTransit;
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using DispatcherVector = std::vector<scoped_refptr<Dispatcher>>;
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// A |Dispatcher| implements Mojo EDK calls that are associated with a
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// particular MojoHandle, with the exception of MojoWait and MojoWaitMany (
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// which are implemented directly in Core.).
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class MOJO_SYSTEM_IMPL_EXPORT Dispatcher
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: public base::RefCountedThreadSafe<Dispatcher> {
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public:
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struct DispatcherInTransit {
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DispatcherInTransit();
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DispatcherInTransit(const DispatcherInTransit& other);
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~DispatcherInTransit();
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scoped_refptr<Dispatcher> dispatcher;
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MojoHandle local_handle;
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};
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enum class Type {
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UNKNOWN = 0,
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MESSAGE_PIPE,
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DATA_PIPE_PRODUCER,
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DATA_PIPE_CONSUMER,
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SHARED_BUFFER,
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WAIT_SET,
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// "Private" types (not exposed via the public interface):
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PLATFORM_HANDLE = -1,
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};
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// All Dispatchers must minimally implement these methods.
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virtual Type GetType() const = 0;
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virtual MojoResult Close() = 0;
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///////////// Watch API ////////////////////
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virtual MojoResult Watch(MojoHandleSignals signals,
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const Watcher::WatchCallback& callback,
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uintptr_t context);
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virtual MojoResult CancelWatch(uintptr_t context);
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///////////// Message pipe API /////////////
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virtual MojoResult WriteMessage(std::unique_ptr<MessageForTransit> message,
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MojoWriteMessageFlags flags);
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virtual MojoResult ReadMessage(std::unique_ptr<MessageForTransit>* message,
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uint32_t* num_bytes,
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MojoHandle* handles,
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uint32_t* num_handles,
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MojoReadMessageFlags flags,
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bool read_any_size);
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///////////// Shared buffer API /////////////
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// |options| may be null. |new_dispatcher| must not be null, but
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// |*new_dispatcher| should be null (and will contain the dispatcher for the
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// new handle on success).
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virtual MojoResult DuplicateBufferHandle(
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const MojoDuplicateBufferHandleOptions* options,
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scoped_refptr<Dispatcher>* new_dispatcher);
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virtual MojoResult MapBuffer(
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uint64_t offset,
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uint64_t num_bytes,
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MojoMapBufferFlags flags,
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std::unique_ptr<PlatformSharedBufferMapping>* mapping);
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///////////// Data pipe consumer API /////////////
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virtual MojoResult ReadData(void* elements,
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uint32_t* num_bytes,
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MojoReadDataFlags flags);
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virtual MojoResult BeginReadData(const void** buffer,
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uint32_t* buffer_num_bytes,
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MojoReadDataFlags flags);
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virtual MojoResult EndReadData(uint32_t num_bytes_read);
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///////////// Data pipe producer API /////////////
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virtual MojoResult WriteData(const void* elements,
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uint32_t* num_bytes,
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MojoWriteDataFlags flags);
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virtual MojoResult BeginWriteData(void** buffer,
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uint32_t* buffer_num_bytes,
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MojoWriteDataFlags flags);
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virtual MojoResult EndWriteData(uint32_t num_bytes_written);
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///////////// Wait set API /////////////
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// Adds a dispatcher to wait on. When the dispatcher satisfies |signals|, it
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// will be returned in the next call to |GetReadyDispatchers()|. If
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// |dispatcher| has been added, it must be removed before adding again,
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// otherwise |MOJO_RESULT_ALREADY_EXISTS| will be returned.
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virtual MojoResult AddWaitingDispatcher(
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const scoped_refptr<Dispatcher>& dispatcher,
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MojoHandleSignals signals,
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uintptr_t context);
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// Removes a dispatcher to wait on. If |dispatcher| has not been added,
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// |MOJO_RESULT_NOT_FOUND| will be returned.
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virtual MojoResult RemoveWaitingDispatcher(
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const scoped_refptr<Dispatcher>& dispatcher);
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// Returns a set of ready dispatchers. |*count| is the maximum number of
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// dispatchers to return, and will contain the number of dispatchers returned
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// in |dispatchers| on completion.
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virtual MojoResult GetReadyDispatchers(uint32_t* count,
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DispatcherVector* dispatchers,
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MojoResult* results,
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uintptr_t* contexts);
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///////////// General-purpose API for all handle types /////////
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// Gets the current handle signals state. (The default implementation simply
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// returns a default-constructed |HandleSignalsState|, i.e., no signals
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// satisfied or satisfiable.) Note: The state is subject to change from other
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// threads.
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virtual HandleSignalsState GetHandleSignalsState() const;
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// Adds an awakable to this dispatcher, which will be woken up when this
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// object changes state to satisfy |signals| with context |context|. It will
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// also be woken up when it becomes impossible for the object to ever satisfy
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// |signals| with a suitable error status.
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//
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// If |signals_state| is non-null, on *failure* |*signals_state| will be set
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// to the current handle signals state (on success, it is left untouched).
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//
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// Returns:
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// - |MOJO_RESULT_OK| if the awakable was added;
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// - |MOJO_RESULT_ALREADY_EXISTS| if |signals| is already satisfied;
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// - |MOJO_RESULT_INVALID_ARGUMENT| if the dispatcher has been closed; and
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// - |MOJO_RESULT_FAILED_PRECONDITION| if it is not (or no longer) possible
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// that |signals| will ever be satisfied.
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virtual MojoResult AddAwakable(Awakable* awakable,
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MojoHandleSignals signals,
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uintptr_t context,
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HandleSignalsState* signals_state);
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// Removes an awakable from this dispatcher. (It is valid to call this
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// multiple times for the same |awakable| on the same object, so long as
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// |AddAwakable()| was called at most once.) If |signals_state| is non-null,
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// |*signals_state| will be set to the current handle signals state.
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virtual void RemoveAwakable(Awakable* awakable,
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HandleSignalsState* signals_state);
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// Informs the caller of the total serialized size (in bytes) and the total
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// number of platform handles and ports needed to transfer this dispatcher
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// across a message pipe.
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//
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// Must eventually be followed by a call to EndSerializeAndClose(). Note that
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// StartSerialize() and EndSerialize() are always called in sequence, and
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// only between calls to BeginTransit() and either (but not both)
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// CompleteTransitAndClose() or CancelTransit().
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//
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// For this reason it is IMPERATIVE that the implementation ensure a
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// consistent serializable state between BeginTransit() and
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// CompleteTransitAndClose()/CancelTransit().
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virtual void StartSerialize(uint32_t* num_bytes,
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uint32_t* num_ports,
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uint32_t* num_platform_handles);
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// Serializes this dispatcher into |destination|, |ports|, and |handles|.
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// Returns true iff successful, false otherwise. In either case the dispatcher
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// will close.
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//
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// NOTE: Transit MAY still fail after this call returns. Implementations
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// should not assume PlatformHandle ownership has transferred until
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// CompleteTransitAndClose() is called. In other words, if CancelTransit() is
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// called, the implementation should retain its PlatformHandles in working
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// condition.
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virtual bool EndSerialize(void* destination,
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ports::PortName* ports,
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PlatformHandle* handles);
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// Does whatever is necessary to begin transit of the dispatcher. This
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// should return |true| if transit is OK, or false if the underlying resource
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// is deemed busy by the implementation.
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virtual bool BeginTransit();
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// Does whatever is necessary to complete transit of the dispatcher, including
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// closure. This is only called upon successfully transmitting an outgoing
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// message containing this serialized dispatcher.
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virtual void CompleteTransitAndClose();
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// Does whatever is necessary to cancel transit of the dispatcher. The
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// dispatcher should remain in a working state and resume normal operation.
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virtual void CancelTransit();
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// Deserializes a specific dispatcher type from an incoming message.
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static scoped_refptr<Dispatcher> Deserialize(
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Type type,
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const void* bytes,
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size_t num_bytes,
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const ports::PortName* ports,
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size_t num_ports,
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PlatformHandle* platform_handles,
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size_t num_platform_handles);
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protected:
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friend class base::RefCountedThreadSafe<Dispatcher>;
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Dispatcher();
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virtual ~Dispatcher();
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DISALLOW_COPY_AND_ASSIGN(Dispatcher);
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};
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// So logging macros and |DCHECK_EQ()|, etc. work.
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MOJO_SYSTEM_IMPL_EXPORT inline std::ostream& operator<<(std::ostream& out,
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Dispatcher::Type type) {
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return out << static_cast<int>(type);
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}
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} // namespace edk
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} // namespace mojo
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#endif // MOJO_EDK_SYSTEM_DISPATCHER_H_
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