/*
 * =====================================================================================
 *
 *       Filename:  shm_msg_queue.cpp
 *
 *    Description:  
 *
 *        Version:  1.0
 *        Created:  2021年04月26日 16时25分05秒
 *       Revision:  none
 *       Compiler:  gcc
 *
 *         Author:  Li Chao (), lichao@aiotlink.com
 *   Organization:  
 *
 * =====================================================================================
 */
#include "shm_msg_queue.h"

using namespace bhome_msg;
using namespace boost::interprocess;

namespace
{
std::string MsgQIdToName(const ShmMsgQueue::MQId id)
{
	char buf[40] = "mqOx";
	int n = sprintf(buf + 4, "%lx", id);
	return std::string(buf, n + 4);
}

} // namespace

ShmMsgQueue::MQId ShmMsgQueue::NewId()
{
	static auto &id = GetData();
	return (++id) * 10;
}
// ShmMsgQueue memory usage: (320 + 16*length) bytes, length >= 2
ShmMsgQueue::ShmMsgQueue(const MQId id, ShmType &segment, const int len) :
    id_(id),
    queue_(segment, MsgQIdToName(id_)) //, AdjustMQLength(len), segment.get_segment_manager())
{
}

ShmMsgQueue::ShmMsgQueue(ShmType &segment, const int len) :
    id_(NewId()),
    queue_(segment, true, MsgQIdToName(id_)) //, AdjustMQLength(len), segment.get_segment_manager())
{
	if (!queue_.IsOk()) {
		throw("error create msgq " + std::to_string(id_));
	}
}

ShmMsgQueue::~ShmMsgQueue() {}

bool ShmMsgQueue::Remove(SharedMemory &shm, const MQId id)
{
	Queue *q = Find(shm, id);
	if (q) {
		MsgI msg;
		while (q->TryRead(msg.OffsetRef())) {
			msg.Release();
		}
	}
	return Shmq::Remove(shm, MsgQIdToName(id));
}

ShmMsgQueue::Queue *ShmMsgQueue::Find(SharedMemory &shm, const MQId remote_id)
{
	return Shmq::Find(shm, MsgQIdToName(remote_id));
}

bool ShmMsgQueue::TrySend(SharedMemory &shm, const MQId remote_id, MsgI msg)
{
	Queue *remote = Find(shm, remote_id);
	bool r = false;
	if (remote) {
		msg.AddRef();
		r = remote->TryWrite(msg.Offset());
		if (!r) {
			msg.Release();
		}
	}
	return r;
}

// Test shows that in the 2 cases:
// 1) build msg first, then find remote queue;
// 2) find remote queue first, then build msg;
// 1 is about 50% faster than 2, maybe cache related.