blob: c1399e10540faea512d8e30cbcf2e879368df00c [file] [log] [blame]
#pragma once
* Copyright (C) 2017 The Android Open Source Project
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* See the License for the specific language governing permissions and
* limitations under the License.
#include <stdlib.h>
#include <atomic>
#include "common/vsoc/shm/base.h"
namespace vsoc {
* Interface that defines signaling and waiting for signal.
class RegionSignalingInterface {
virtual ~RegionSignalingInterface(){};
// Post a signal to the guest, the host, or both.
// See futex(2) FUTEX_WAKE for details.
// sides_to_signal: controls where the signal is sent
// signal_addr: the memory location to signal. Must be within the region.
virtual void SendSignal(layout::Sides sides_to_signal,
std::atomic<uint32_t>* signal_addr) = 0;
// This implements the following:
// if (*signal_addr == last_observed_value)
// wait_for_signal_at(signal_addr);
// Note: the caller still needs to check the value at signal_addr because
// this function may return early for reasons that are implementation-defined.
// See futex(2) FUTEX_WAIT for details.
// signal_addr: the memory that will be signaled. Must be within the region.
// last_observed_value: the value that motivated the calling code to wait.
// The return values are:
// -1 on failure
// 0 indicates success with no tuning information
// >0 indicates success. The number indicates how many times the thread
// woke before it could return.
// Large values indicate that the regions should be tuned.
virtual int WaitForSignal(std::atomic<uint32_t>* signal_addr,
uint32_t last_observed_value) = 0;
} // namespace vsoc