mojo/core/handle_signals_state.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_CORE_HANDLE_SIGNALS_STATE_H_
#define MOJO_CORE_HANDLE_SIGNALS_STATE_H_

#include "mojo/core/system_impl_export.h"
#include "mojo/public/c/system/types.h"

namespace mojo {
namespace core {

// A convenience wrapper around the MojoHandleSignalsState struct.
//
// NOTE: This is duplicated in the public C++ SDK to avoid circular
// dependencies between the EDK and the public SDK.
struct MOJO_SYSTEM_IMPL_EXPORT HandleSignalsState final
    : public MojoHandleSignalsState {
  HandleSignalsState() {
    satisfied_signals = MOJO_HANDLE_SIGNAL_NONE;
    satisfiable_signals = MOJO_HANDLE_SIGNAL_NONE;
  }

  HandleSignalsState(MojoHandleSignals satisfied,
                     MojoHandleSignals satisfiable) {
    satisfied_signals = satisfied;
    satisfiable_signals = satisfiable;
  }

  bool operator==(const HandleSignalsState& other) const {
    return satisfied_signals == other.satisfied_signals &&
           satisfiable_signals == other.satisfiable_signals;
  }

  // TODO(rockot): Remove this in favor of operator==.
  bool equals(const HandleSignalsState& other) const {
    return satisfied_signals == other.satisfied_signals &&
           satisfiable_signals == other.satisfiable_signals;
  }

  bool satisfies_any(MojoHandleSignals signals) const {
    return !!(satisfied_signals & signals);
  }

  bool satisfies_all(MojoHandleSignals signals) const {
    return (satisfied_signals & signals) == signals;
  }

  bool can_satisfy_any(MojoHandleSignals signals) const {
    return !!(satisfiable_signals & signals);
  }

  // The handle is currently readable. May apply to a message pipe handle or
  // data pipe consumer handle.
  bool readable() const { return satisfies_any(MOJO_HANDLE_SIGNAL_READABLE); }

  // The handle is currently writable. May apply to a message pipe handle or
  // data pipe producer handle.
  bool writable() const { return satisfies_any(MOJO_HANDLE_SIGNAL_WRITABLE); }

  // The handle's peer is closed. May apply to any message pipe or data pipe
  // handle.
  bool peer_closed() const {
    return satisfies_any(MOJO_HANDLE_SIGNAL_PEER_CLOSED);
  }

  // The handle's peer exists in a remote execution context (e.g. in another
  // process.)
  bool peer_remote() const {
    return satisfies_any(MOJO_HANDLE_SIGNAL_PEER_REMOTE);
  }

  // Indicates whether the handle has exceeded some quota limit.
  bool quota_exceeded() const {
    return satisfies_any(MOJO_HANDLE_SIGNAL_QUOTA_EXCEEDED);
  }

  // The handle will never be |readable()| again.
  bool never_readable() const {
    return !can_satisfy_any(MOJO_HANDLE_SIGNAL_READABLE);
  }

  // The handle will never be |writable()| again.
  bool never_writable() const {
    return !can_satisfy_any(MOJO_HANDLE_SIGNAL_WRITABLE);
  }

  // The handle can never indicate |peer_closed()|. Never true for message pipe
  // or data pipe handles (they can always signal peer closure), but always true
  // for other types of handles (they have no peer.)
  bool never_peer_closed() const {
    return !can_satisfy_any(MOJO_HANDLE_SIGNAL_PEER_CLOSED);
  }

  // The handle will never indicate |peer_remote()| again. True iff the peer is
  // known to be closed.
  bool never_peer_remote() const {
    return !can_satisfy_any(MOJO_HANDLE_SIGNAL_PEER_REMOTE);
  }

  // (Copy and assignment allowed.)
};

static_assert(sizeof(HandleSignalsState) == sizeof(MojoHandleSignalsState),
              "HandleSignalsState should add no overhead");

}  // namespace core
}  // namespace mojo

#endif  // MOJO_CORE_HANDLE_SIGNALS_STATE_H_