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cuberite-2a/src/OSSupport/SocketThreads.cpp

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// cSocketThreads.cpp
// Implements the cSocketThreads class representing the heart of MCS's client networking.
// This object takes care of network communication, groups sockets into threads and uses as little threads as possible for full read / write support
// For more detail, see http://forum.mc-server.org/showthread.php?tid=327
#include "Globals.h"
#include "SocketThreads.h"
#include "Errors.h"
///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// cSocketThreads:
cSocketThreads::cSocketThreads(void)
{
}
cSocketThreads::~cSocketThreads()
{
for (cSocketThreadList::iterator itr = m_Threads.begin(); itr != m_Threads.end(); ++itr)
{
delete *itr;
} // for itr - m_Threads[]
m_Threads.clear();
}
bool cSocketThreads::AddClient(const cSocket & a_Socket, cCallback * a_Client)
{
// Add a (socket, client) pair for processing, data from a_Socket is to be sent to a_Client
// Try to add to existing threads:
cCSLock Lock(m_CS);
for (cSocketThreadList::iterator itr = m_Threads.begin(); itr != m_Threads.end(); ++itr)
{
if ((*itr)->IsValid() && (*itr)->HasEmptySlot())
{
(*itr)->AddClient(a_Socket, a_Client);
return true;
}
}
// No thread has free space, create a new one:
LOGD("Creating a new cSocketThread (currently have " SIZE_T_FMT ")", m_Threads.size());
cSocketThread * Thread = new cSocketThread(this);
if (!Thread->Start())
{
// There was an error launching the thread (but it was already logged along with the reason)
LOGERROR("A new cSocketThread failed to start");
delete Thread;
return false;
}
Thread->AddClient(a_Socket, a_Client);
m_Threads.push_back(Thread);
return true;
}
void cSocketThreads::RemoveClient(const cCallback * a_Client)
{
// Remove the associated socket and the client from processing
cCSLock Lock(m_CS);
for (cSocketThreadList::iterator itr = m_Threads.begin(); itr != m_Threads.end(); ++itr)
{
if ((*itr)->RemoveClient(a_Client))
{
return;
}
} // for itr - m_Threads[]
ASSERT(!"Removing an unknown client");
}
void cSocketThreads::NotifyWrite(const cCallback * a_Client)
{
// Notifies the thread responsible for a_Client that the client has something to write
cCSLock Lock(m_CS);
for (cSocketThreadList::iterator itr = m_Threads.begin(); itr != m_Threads.end(); ++itr)
{
if ((*itr)->NotifyWrite(a_Client))
{
return;
}
} // for itr - m_Threads[]
// Cannot assert - this normally happens if a client disconnects and has pending packets, the cServer::cNotifyWriteThread will call this on invalid clients too
// ASSERT(!"Notifying write to an unknown client");
}
void cSocketThreads::Write(const cCallback * a_Client, const AString & a_Data)
{
// Puts a_Data into outgoing data queue for a_Client
cCSLock Lock(m_CS);
for (cSocketThreadList::iterator itr = m_Threads.begin(); itr != m_Threads.end(); ++itr)
{
if ((*itr)->Write(a_Client, a_Data))
{
return;
}
} // for itr - m_Threads[]
// This may be perfectly legal, if the socket has been destroyed and the client is finishing up
// ASSERT(!"Writing to an unknown socket");
}
////////////////////////////////////////////////////////////////////////////////
// cSocketThreads::cSocketThread:
cSocketThreads::cSocketThread::cSocketThread(cSocketThreads * a_Parent) :
cIsThread("cSocketThread"),
m_Parent(a_Parent),
m_NumSlots(0)
{
// Nothing needed yet
}
cSocketThreads::cSocketThread::~cSocketThread()
{
m_ShouldTerminate = true;
// Notify the thread:
ASSERT(m_ControlSocket2.IsValid());
m_ControlSocket2.Send("a", 1);
// Wait for the thread to finish:
Wait();
// Close the control sockets:
m_ControlSocket1.CloseSocket();
m_ControlSocket2.CloseSocket();
}
void cSocketThreads::cSocketThread::AddClient(const cSocket & a_Socket, cCallback * a_Client)
{
ASSERT(m_Parent->m_CS.IsLockedByCurrentThread());
ASSERT(m_NumSlots < MAX_SLOTS); // Use HasEmptySlot() to check before adding
m_Slots[m_NumSlots].m_Client = a_Client;
m_Slots[m_NumSlots].m_Socket = a_Socket;
m_Slots[m_NumSlots].m_Socket.SetNonBlocking();
m_Slots[m_NumSlots].m_Outgoing.clear();
m_Slots[m_NumSlots].m_State = sSlot::ssNormal;
m_NumSlots++;
// Notify the thread of the change:
ASSERT(m_ControlSocket2.IsValid());
m_ControlSocket2.Send("a", 1);
}
bool cSocketThreads::cSocketThread::RemoveClient(const cCallback * a_Client)
{
ASSERT(m_Parent->m_CS.IsLockedByCurrentThread());
if (m_NumSlots == 0)
{
return false;
}
for (int i = m_NumSlots - 1; i >= 0 ; --i)
{
if (m_Slots[i].m_Client != a_Client)
{
continue;
}
// Found the slot:
if (m_Slots[i].m_State == sSlot::ssRemoteClosed)
{
// The remote has already closed the socket, remove the slot altogether:
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if (m_Slots[i].m_Socket.IsValid())
{
m_Slots[i].m_Socket.CloseSocket();
}
m_Slots[i] = m_Slots[--m_NumSlots];
}
else
{
// Query and queue the last batch of outgoing data:
AString Data;
m_Slots[i].m_Client->GetOutgoingData(Data);
m_Slots[i].m_Outgoing.append(Data);
if (m_Slots[i].m_Outgoing.empty())
{
// No more outgoing data, shut the socket down immediately:
m_Slots[i].m_Socket.ShutdownReadWrite();
m_Slots[i].m_State = sSlot::ssShuttingDown;
}
else
{
// More data to send, shut down reading and wait for the rest to get sent:
m_Slots[i].m_State = sSlot::ssWritingRestOut;
}
m_Slots[i].m_Client = NULL;
}
// Notify the thread of the change:
ASSERT(m_ControlSocket2.IsValid());
m_ControlSocket2.Send("r", 1);
return true;
} // for i - m_Slots[]
// Not found
return false;
}
bool cSocketThreads::cSocketThread::HasClient(const cCallback * a_Client) const
{
ASSERT(m_Parent->m_CS.IsLockedByCurrentThread());
for (int i = m_NumSlots - 1; i >= 0; --i)
{
if (m_Slots[i].m_Client == a_Client)
{
return true;
}
} // for i - m_Slots[]
return false;
}
bool cSocketThreads::cSocketThread::HasSocket(const cSocket * a_Socket) const
{
for (int i = m_NumSlots - 1; i >= 0; --i)
{
if (m_Slots[i].m_Socket == *a_Socket)
{
return true;
}
} // for i - m_Slots[]
return false;
}
bool cSocketThreads::cSocketThread::NotifyWrite(const cCallback * a_Client)
{
ASSERT(m_Parent->m_CS.IsLockedByCurrentThread());
if (HasClient(a_Client))
{
// Notify the thread that there's another packet in the queue:
ASSERT(m_ControlSocket2.IsValid());
m_ControlSocket2.Send("q", 1);
return true;
}
return false;
}
bool cSocketThreads::cSocketThread::Write(const cCallback * a_Client, const AString & a_Data)
{
ASSERT(m_Parent->m_CS.IsLockedByCurrentThread());
for (int i = m_NumSlots - 1; i >= 0; --i)
{
if (m_Slots[i].m_Client == a_Client)
{
m_Slots[i].m_Outgoing.append(a_Data);
// Notify the thread that there's data in the queue:
ASSERT(m_ControlSocket2.IsValid());
m_ControlSocket2.Send("q", 1);
return true;
}
} // for i - m_Slots[]
return false;
}
bool cSocketThreads::cSocketThread::Start(void)
{
// Create the control socket listener
m_ControlSocket2 = cSocket::CreateSocket(cSocket::IPv4);
if (!m_ControlSocket2.IsValid())
{
LOGERROR("Cannot create a Control socket for a cSocketThread (\"%s\"); continuing, but server may be unreachable from now on.", cSocket::GetLastErrorString().c_str());
return false;
}
if (!m_ControlSocket2.BindToLocalhostIPv4(cSocket::ANY_PORT))
{
LOGERROR("Cannot bind a Control socket for a cSocketThread (\"%s\"); continuing, but server may be unreachable from now on.", cSocket::GetLastErrorString().c_str());
m_ControlSocket2.CloseSocket();
return false;
}
if (!m_ControlSocket2.Listen(1))
{
LOGERROR("Cannot listen on a Control socket for a cSocketThread (\"%s\"); continuing, but server may be unreachable from now on.", cSocket::GetLastErrorString().c_str());
m_ControlSocket2.CloseSocket();
return false;
}
if (m_ControlSocket2.GetPort() == 0)
{
LOGERROR("Cannot determine Control socket port (\"%s\"); conitnuing, but the server may be unreachable from now on.", cSocket::GetLastErrorString().c_str());
m_ControlSocket2.CloseSocket();
return false;
}
// Start the thread
if (!super::Start())
{
LOGERROR("Cannot start new cSocketThread");
m_ControlSocket2.CloseSocket();
return false;
}
// Finish connecting the control socket by accepting connection from the thread's socket
cSocket tmp = m_ControlSocket2.AcceptIPv4();
if (!tmp.IsValid())
{
LOGERROR("Cannot link Control sockets for a cSocketThread (\"%s\"); continuing, but server may be unreachable from now on.", cSocket::GetLastErrorString().c_str());
m_ControlSocket2.CloseSocket();
return false;
}
m_ControlSocket2.CloseSocket();
m_ControlSocket2 = tmp;
return true;
}
void cSocketThreads::cSocketThread::Execute(void)
{
// Connect the "client" part of the Control socket:
m_ControlSocket1 = cSocket::CreateSocket(cSocket::IPv4);
ASSERT(m_ControlSocket2.GetPort() != 0); // We checked in the Start() method, but let's be sure
if (!m_ControlSocket1.ConnectToLocalhostIPv4(m_ControlSocket2.GetPort()))
{
LOGERROR("Cannot connect Control sockets for a cSocketThread (\"%s\"); continuing, but the server may be unreachable from now on.", cSocket::GetLastErrorString().c_str());
m_ControlSocket2.CloseSocket();
return;
}
// The main thread loop:
while (!m_ShouldTerminate)
{
// Read outgoing data from the clients:
QueueOutgoingData();
// Put sockets into the sets
fd_set fdRead;
fd_set fdWrite;
cSocket::xSocket Highest = m_ControlSocket1.GetSocket();
PrepareSets(&fdRead, &fdWrite, Highest);
// Wait for the sockets:
timeval Timeout;
Timeout.tv_sec = 5;
Timeout.tv_usec = 0;
if (select(Highest + 1, &fdRead, &fdWrite, NULL, &Timeout) == -1)
{
LOG("select() call failed in cSocketThread: \"%s\"", cSocket::GetLastErrorString().c_str());
continue;
}
// Perform the IO:
ReadFromSockets(&fdRead);
WriteToSockets(&fdWrite);
CleanUpShutSockets();
} // while (!mShouldTerminate)
}
void cSocketThreads::cSocketThread::PrepareSets(fd_set * a_Read, fd_set * a_Write, cSocket::xSocket & a_Highest)
{
FD_ZERO(a_Read);
FD_ZERO(a_Write);
FD_SET(m_ControlSocket1.GetSocket(), a_Read);
cCSLock Lock(m_Parent->m_CS);
for (int i = m_NumSlots - 1; i >= 0; --i)
{
if (!m_Slots[i].m_Socket.IsValid())
{
continue;
}
if (m_Slots[i].m_State == sSlot::ssRemoteClosed)
{
// This socket won't provide nor consume any data anymore, don't put it in the Set
continue;
}
cSocket::xSocket s = m_Slots[i].m_Socket.GetSocket();
FD_SET(s, a_Read);
if (s > a_Highest)
{
a_Highest = s;
}
if (!m_Slots[i].m_Outgoing.empty())
{
// There's outgoing data for the socket, put it in the Write set
FD_SET(s, a_Write);
}
} // for i - m_Slots[]
}
void cSocketThreads::cSocketThread::ReadFromSockets(fd_set * a_Read)
{
// Read on available sockets:
// Reset Control socket state:
if (FD_ISSET(m_ControlSocket1.GetSocket(), a_Read))
{
char Dummy[128];
m_ControlSocket1.Receive(Dummy, sizeof(Dummy), 0);
}
// Read from clients:
cCSLock Lock(m_Parent->m_CS);
for (int i = m_NumSlots - 1; i >= 0; --i)
{
cSocket::xSocket Socket = m_Slots[i].m_Socket.GetSocket();
if (!cSocket::IsValidSocket(Socket) || !FD_ISSET(Socket, a_Read))
{
continue;
}
char Buffer[1024];
int Received = m_Slots[i].m_Socket.Receive(Buffer, ARRAYCOUNT(Buffer), 0);
if (Received <= 0)
{
if (cSocket::GetLastError() != cSocket::ErrWouldBlock)
{
// The socket has been closed by the remote party
switch (m_Slots[i].m_State)
{
case sSlot::ssNormal:
{
// Notify the callback that the remote has closed the socket; keep the slot
m_Slots[i].m_Client->SocketClosed();
m_Slots[i].m_State = sSlot::ssRemoteClosed;
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m_Slots[i].m_Socket.CloseSocket();
break;
}
case sSlot::ssWritingRestOut:
case sSlot::ssShuttingDown:
case sSlot::ssShuttingDown2:
{
// Force-close the socket and remove the slot:
m_Slots[i].m_Socket.CloseSocket();
m_Slots[i] = m_Slots[--m_NumSlots];
break;
}
default:
{
LOG("%s: Unexpected socket state: %d (%s)",
__FUNCTION__, m_Slots[i].m_Socket.GetSocket(), m_Slots[i].m_Socket.GetIPString().c_str()
);
ASSERT(!"Unexpected socket state");
break;
}
} // switch (m_Slots[i].m_State)
}
}
else
{
if (m_Slots[i].m_Client != NULL)
{
m_Slots[i].m_Client->DataReceived(Buffer, Received);
}
}
} // for i - m_Slots[]
}
void cSocketThreads::cSocketThread::WriteToSockets(fd_set * a_Write)
{
// Write to available client sockets:
cCSLock Lock(m_Parent->m_CS);
for (int i = m_NumSlots - 1; i >= 0; --i)
{
cSocket::xSocket Socket = m_Slots[i].m_Socket.GetSocket();
if (!cSocket::IsValidSocket(Socket) || !FD_ISSET(Socket, a_Write))
{
continue;
}
if (m_Slots[i].m_Outgoing.empty())
{
// Request another chunk of outgoing data:
if (m_Slots[i].m_Client != NULL)
{
AString Data;
m_Slots[i].m_Client->GetOutgoingData(Data);
m_Slots[i].m_Outgoing.append(Data);
}
if (m_Slots[i].m_Outgoing.empty())
{
// No outgoing data is ready
if (m_Slots[i].m_State == sSlot::ssWritingRestOut)
{
m_Slots[i].m_State = sSlot::ssShuttingDown;
m_Slots[i].m_Socket.ShutdownReadWrite();
}
continue;
}
} // if (outgoing data is empty)
if (m_Slots[i].m_State == sSlot::ssRemoteClosed)
{
continue;
}
if (!SendDataThroughSocket(m_Slots[i].m_Socket, m_Slots[i].m_Outgoing))
{
int Err = cSocket::GetLastError();
LOGWARNING("Error %d while writing to client \"%s\", disconnecting. \"%s\"", Err, m_Slots[i].m_Socket.GetIPString().c_str(), GetOSErrorString(Err).c_str());
m_Slots[i].m_Socket.CloseSocket();
if (m_Slots[i].m_Client != NULL)
{
m_Slots[i].m_Client->SocketClosed();
}
continue;
}
if (m_Slots[i].m_Outgoing.empty() && (m_Slots[i].m_State == sSlot::ssWritingRestOut))
{
m_Slots[i].m_State = sSlot::ssShuttingDown;
m_Slots[i].m_Socket.ShutdownReadWrite();
}
// _X: If there's data left, it means the client is not reading fast enough, the server would unnecessarily spin in the main loop with zero actions taken; so signalling is disabled
// This means that if there's data left, it will be sent only when there's incoming data or someone queues another packet (for any socket handled by this thread)
/*
// If there's any data left, signalize the Control socket:
if (!m_Slots[i].m_Outgoing.empty())
{
ASSERT(m_ControlSocket2.IsValid());
m_ControlSocket2.Send("q", 1);
}
*/
} // for i - m_Slots[i]
}
bool cSocketThreads::cSocketThread::SendDataThroughSocket(cSocket & a_Socket, AString & a_Data)
{
// Send data in smaller chunks, so that the OS send buffers aren't overflown easily
while (!a_Data.empty())
{
size_t NumToSend = std::min(a_Data.size(), (size_t)1024);
int Sent = a_Socket.Send(a_Data.data(), NumToSend);
if (Sent < 0)
{
int Err = cSocket::GetLastError();
if (Err == cSocket::ErrWouldBlock)
{
// The OS send buffer is full, leave the outgoing data for the next time
return true;
}
// An error has occured
return false;
}
if (Sent == 0)
{
a_Socket.CloseSocket();
return true;
}
a_Data.erase(0, Sent);
}
return true;
}
void cSocketThreads::cSocketThread::CleanUpShutSockets(void)
{
cCSLock Lock(m_Parent->m_CS);
for (int i = m_NumSlots - 1; i >= 0; i--)
{
switch (m_Slots[i].m_State)
{
case sSlot::ssShuttingDown2:
{
// The socket has reached the shutdown timeout, close it and clear its slot:
m_Slots[i].m_Socket.CloseSocket();
m_Slots[i] = m_Slots[--m_NumSlots];
break;
}
case sSlot::ssShuttingDown:
{
// The socket has been shut down for a single thread loop, let it loop once more before closing:
m_Slots[i].m_State = sSlot::ssShuttingDown2;
break;
}
default: break;
}
} // for i - m_Slots[]
}
void cSocketThreads::cSocketThread::QueueOutgoingData(void)
{
cCSLock Lock(m_Parent->m_CS);
for (int i = 0; i < m_NumSlots; i++)
{
if (m_Slots[i].m_Client != NULL)
{
AString Data;
m_Slots[i].m_Client->GetOutgoingData(Data);
m_Slots[i].m_Outgoing.append(Data);
}
if (m_Slots[i].m_Outgoing.empty())
{
// No outgoing data is ready
if (m_Slots[i].m_State == sSlot::ssWritingRestOut)
{
// The socket doesn't want to be kept alive anymore, and doesn't have any remaining data to send.
// Shut it down and then close it after a timeout, or when the other side agrees
m_Slots[i].m_State = sSlot::ssShuttingDown;
m_Slots[i].m_Socket.ShutdownReadWrite();
}
continue;
}
}
}