SVNetwork Class Reference

#include <svutil.h>

Public Member Functions
	SVNetwork (const char *hostname, int port)
	Set up a connection to hostname on port. More...
	~SVNetwork ()
	Destructor. More...
void	Send (const char *msg)
	Put a message in the messagebuffer to the server and try to send it. More...
char *	Receive ()
void	Close ()
	Close the connection to the server. More...
void	Flush ()
	Flush the buffer. More...

Detailed Description

The SVNetwork class takes care of the remote connection for ScrollView This means setting up and maintaining a remote connection, sending and receiving messages and closing the connection. It is designed to work on both Linux and Windows.

Definition at line 66 of file svutil.h.

Constructor & Destructor Documentation

SVNetwork()

SVNetwork::SVNetwork	(	const char *	hostname,
		int	port
	)

Set up a connection to hostname on port.

Definition at line 264 of file svutil.cpp.

                                                   {
  msg_buffer_in_ = new char[kMaxMsgSize + 1];
  msg_buffer_in_[0] = '\0';
 
  has_content = false;
  buffer_ptr_ = nullptr;
 
  struct addrinfo *addr_info = nullptr;
  char port_str[40];
  snprintf(port_str, 40, "%d", port);
#ifdef _WIN32
  // Initialize Winsock
  WSADATA wsaData;
  int iResult = WSAStartup(MAKEWORD(2, 2), &wsaData);
  if (iResult != 0) {
    std::cerr << "WSAStartup failed: " << iResult << std::endl;
  }
#endif  // _WIN32
 
  if (getaddrinfo(hostname, port_str, nullptr, &addr_info) != 0) {
    std::cerr << "Error resolving name for ScrollView host "
              << std::string(hostname) << ":" << port << std::endl;
#ifdef _WIN32
    WSACleanup();
#endif  // _WIN32
  }
 
  stream_ = socket(addr_info->ai_family, addr_info->ai_socktype,
                   addr_info->ai_protocol);
 
  if (stream_ < 0) {
    std::cerr << "Failed to open socket" << std::endl;
  } else if (connect(stream_, addr_info->ai_addr, addr_info->ai_addrlen) < 0) {
    // If server is not there, we will start a new server as local child process.
    const char* scrollview_path = getenv("SCROLLVIEW_PATH");
    if (scrollview_path == nullptr) {
#ifdef SCROLLVIEW_PATH
#define _STR(a) #a
#define _XSTR(a) _STR(a)
      scrollview_path = _XSTR(SCROLLVIEW_PATH);
#undef _XSTR
#undef _STR
#else
      scrollview_path = ".";
#endif
    }
    const char *prog = ScrollViewProg();
    std::string command = ScrollViewCommand(scrollview_path);
    SVSync::StartProcess(prog, command.c_str());
 
    // Wait for server to show up.
    // Note: There is no exception handling in case the server never turns up.
 
    Close();
    for (;;) {
      stream_ = socket(addr_info->ai_family, addr_info->ai_socktype,
                       addr_info->ai_protocol);
      if (stream_ >= 0) {
        if (connect(stream_, addr_info->ai_addr, addr_info->ai_addrlen) == 0) {
          break;
        }
 
        Close();
 
        std::cout << "ScrollView: Waiting for server...\n";
        std::this_thread::sleep_for(std::chrono::seconds(1));
      }
    }
  }
#ifdef _WIN32
  // WSACleanup();  // This cause ScrollView windows is not displayed
#endif  // _WIN32
  freeaddrinfo(addr_info);
}

~SVNetwork()

SVNetwork::~SVNetwork

(

)

Destructor.

Definition at line 339 of file svutil.cpp.

                      {
  Close();
  delete[] msg_buffer_in_;
}

Member Function Documentation

Close()

void SVNetwork::Close

(

)

Close the connection to the server.

Definition at line 213 of file svutil.cpp.

                      {
#ifdef _WIN32
  closesocket(stream_);
#else
  close(stream_);
#endif
  // Mark stream_ as invalid.
  stream_ = -1;
}

Flush()

void SVNetwork::Flush

(

)

Flush the buffer.

Definition at line 155 of file svutil.cpp.

                      {
  std::lock_guard<std::mutex> guard(mutex_send_);
  while (!msg_buffer_out_.empty()) {
    int i = send(stream_, msg_buffer_out_.c_str(), msg_buffer_out_.length(), 0);
    msg_buffer_out_.erase(0, i);
  }
}

Receive()

char * SVNetwork::Receive

(

)

Receive a message from the server. This will always return one line of char* (denoted by \n).

Definition at line 165 of file svutil.cpp.

                         {
  char* result = nullptr;
#if defined(_WIN32) || defined(__CYGWIN__)
  if (has_content) { result = strtok (nullptr, "\n"); }
#else
  if (buffer_ptr_ != nullptr) { result = strtok_r(nullptr, "\n", &buffer_ptr_); }
#endif
 
  // This means there is something left in the buffer and we return it.
  if (result != nullptr) { return result;
  // Otherwise, we read from the stream_.
  } else {
    buffer_ptr_ = nullptr;
    has_content = false;
 
    // The timeout length is not really important since we are looping anyway
    // until a new message is delivered.
    struct timeval tv;
    tv.tv_sec = 10;
    tv.tv_usec = 0;
 
    // Set the flags to return when the stream_ is ready to be read.
    fd_set readfds;
    FD_ZERO(&readfds);
    FD_SET(stream_, &readfds);
 
    int i = select(stream_+1, &readfds, nullptr, nullptr, &tv);
 
    // The stream_ died.
    if (i == 0) { return nullptr; }
 
    // Read the message buffer.
    i = recv(stream_, msg_buffer_in_, kMaxMsgSize, 0);
 
    // Server quit (0) or error (-1).
    if (i <= 0) { return nullptr; }
    msg_buffer_in_[i] = '\0';
    has_content = true;
#ifdef _WIN32
    return strtok(msg_buffer_in_, "\n");
#else
    // Setup a new string tokenizer.
    return strtok_r(msg_buffer_in_, "\n", &buffer_ptr_);
#endif
  }
}

Send()

void SVNetwork::Send

(

const char *

msg

)

Put a message in the messagebuffer to the server and try to send it.

Definition at line 149 of file svutil.cpp.

                                    {
  std::lock_guard<std::mutex> guard(mutex_send_);
  msg_buffer_out_.append(msg);
}

---

The documentation for this class was generated from the following files:

• /tesseract/src/viewer/svutil.h
• /tesseract/src/viewer/svutil.cpp