source: Evidence/Evidence.cc@ 227

/********************************************************************\

  General code to start a server of the Evidence Control System
  
  - The server is started with the given name.
  - DIM exit and error handlers are implemented.
  - A Message service is published with severity encoding. It can be updated
    with the Message() method. The text will also be logged.
  - If the severity of a Message() call is FATAL, exit() will be called (with
    this severity, the call to Message() is guranteed not to return).
  - Configuration data can be requested by GetConfig(). 
  - Signal handlers to ignore common signals are installed.
    These signals will then cause pause() to return which can be used
        by the application to terminate gracefully.
  - The static method ToString() converts the contents of a
    DIMInfo service into text
  - A terminate-handler is installed for catching unhandled C++ exceptions.

  Memory allocated by the non-static methods will be freed by the
  class destructor.
  
  Oliver Grimm, June 2010
 
\********************************************************************/

#include "Evidence.h"
using namespace std;

//////////////////////////
// EvidenceServer Class //
//////////////////////////

EvidenceServer *ThisServer;

// Constructor starts server with given name
EvidenceServer::EvidenceServer(const char *Name) {

  // Initialize
  MessageService = NULL;
  MessageData = NULL;
  ExitRequest = false;
  ThisServer = this;
  ServerName = Name;

  // Catch some signals
  signal(SIGQUIT, &SignalHandler);  // CTRL-Backspace
  signal(SIGTERM, &SignalHandler);  // Termination signal
  signal(SIGINT, &SignalHandler);   // CTRL-C
  signal(SIGHUP, &SignalHandler);   // Terminal closed

  // Catch C++ unhandled exceptions
  set_terminate(Terminate);

  // Subscribe to modify service for keeping track of config file changes
  ModifyInfo = new class ConfigUpdate();

  // Message service and initial message
  MessageService = new DimService((ServerName+"/Message").c_str(), (char *) "I:1;C", NULL, 0);

  string Rev(EVIDENCE_REVISION); 
  Message(INFO, "Server started (%s, compiled %s %s)", (Rev.substr(1, Rev.size()-3)).c_str(),__DATE__, __TIME__);

  // Start server
  start(Name);
  addExitHandler(this);  
}

// Destructor: Free memory
EvidenceServer::~EvidenceServer() {

  Message(INFO, "Server stopped");
  
  for (unsigned int i=0; i<ConfigList.size(); i++) delete[] ConfigList[i].Value;
  delete ModifyInfo;
  delete MessageService;
  delete MessageData;
}

// DIM exit handler
void EvidenceServer::exitHandler(int Code) {

  Message(INFO, "Exit handler called (DIM exit code %d)", Code);
  exit(EXIT_SUCCESS);
}

// DIM error handler
void EvidenceServer::errorHandler(int Severity, int Code, char *Text) {   
  Message(ERROR, "%s (DIM error code %d, DIM severity %d)\n", Text, Code, Severity);
}

// Set server message (if Severity is FATAL, exit() will be invoked)
void EvidenceServer::Message(MessageType Severity, const char *Format, ...) {

  static const char* StateString[] = {"Info", "Warn", "Error", "Fatal"};
  static char ErrorString[] = "vasprintf() failed in Message()";
  char *Text;
  
  // Assemble message from application
  va_list ArgumentPointer;
  va_start(ArgumentPointer, Format);
  if (vasprintf(&Text, Format, ArgumentPointer) == -1) {
        Text = ErrorString;
        Severity = ERROR;
  }
  va_end(ArgumentPointer);

  // Generate new Message structure and free text
  struct Message *NewMsg = (struct Message *) new char [sizeof(struct Message)+strlen(Text)+1];
  NewMsg->Severity = Severity;
  strcpy(NewMsg->Text, Text);
  if (Text != ErrorString) free(Text);
  
  // Send message to console and log file
  printf("%s (%s): %s\n", MessageService->getName(), StateString[Severity], NewMsg->Text);
  SendToLog("%s (%s): %s", MessageService->getName(), StateString[Severity], NewMsg->Text);

  // Update DIM message service, then delete old message
  if (MessageService != NULL) {
        MessageService->updateService(NewMsg, sizeof(struct Message)+strlen(NewMsg->Text)+1);
  }
  delete MessageData;
  MessageData = NewMsg;

  // Terminate if severity if FATAL  
  if (Severity == FATAL) exit(EXIT_FAILURE);
}


// Set to central logging server with non-blocking command (may be used in DIM handler)
void EvidenceServer::SendToLog(const char *Format, ...) {

  char *Buffer;
  int Ret;

  // Evaluate variable argument list
  va_list ArgumentPointer;
  va_start(ArgumentPointer, Format);
  Ret = vasprintf(&Buffer, Format, ArgumentPointer);
  va_end(ArgumentPointer);

  // Send to logger
  if (Ret != -1) {
        DimClient::sendCommandNB("DColl/Log", Buffer);
        free (Buffer);
  }
  else Message(ERROR, "Could not create logging text in SendToLog(), vasprintf() failed");
}


// Get configuration data
//
// Program terminates if data is missing and no default given. Actual configuration
// request will be made only if config file has modification since last request.
// The memory allocated by all calls to this function will be freed by
// the destructor.
char* EvidenceServer::GetConfig(string Item, const char *Default) {
  
  int ItemNo = -1;
  
  // Check if configuration request already in list
  for (unsigned int i=0; i<ConfigList.size(); i++) if (ConfigList[i].Name == Item) {
        // Return original value if still up to date
        if (ConfigList[i].Time >= ModifyInfo->LastModifyTime) return ConfigList[i].Value;

        // Otherwise, free memory of old value
        delete[] ConfigList[i].Value;
        ItemNo = i;
        break;
  } 

  // Make configuration request
  DimRpcInfo Config((char *) "ConfigRequest", NO_LINK);
  Config.setData((char *) (ServerName + " " + Item).c_str());
  char *Result = Config.getString();

  // Terminate if not successful
  if (!EvidenceServer::ServiceOK(&Config)) {
    if (Default == NULL) Message(FATAL, "Configuration server unreachable, can't get '%s'", Item.c_str());
        Result = (char *) Default;
  }

  if (strlen(Result) == 0) {
    if (Default == NULL) Message(FATAL, "Missing configuration data '%s'", Item.c_str());
        Result = (char *) Default;
  }

  // Enlarge list if necessary
  if (ItemNo == -1) {
    struct ConfigItem New;
    ConfigList.push_back(New);
        ItemNo = ConfigList.size()-1;
  }

  // Create new entry in item list, allocate memory and copy data to this memory
  ConfigList[ItemNo].Name = Item;
  ConfigList[ItemNo].Value = new char [strlen(Result)+1];
  strcpy(ConfigList[ItemNo].Value, Result);
  ConfigList[ItemNo].Time = ModifyInfo->LastModifyTime;

  // Return address to configuration value  
  return ConfigList[ItemNo].Value;
}


// ====== Static methods ======

// Signal handler (causes pause() and other syscalls to return)
void EvidenceServer::SignalHandler(int Signal) {

  static bool Called = false;

  // At first invocation just request exit
  if (!Called) {
        Called = true;
        ThisServer->ExitRequest = true;
        return;
  }

  // If invoked twice, call exit()
  ThisServer->Message(ThisServer->WARN, "Signal handler called again, invoking exit() (signal %d)", Signal);
  exit(EXIT_FAILURE);
}

// C++ exception handler (derived from gcc __verbose_terminate_handler())
void EvidenceServer::Terminate() {

  static char Msg[STATUS_SIZE];
  static bool Terminating = false;

  if (Terminating) {
        snprintf(Msg, sizeof(Msg), "%s: Terminate() called recursively, calling abort()", ThisServer->MessageService->getName());
        printf("%s\n", Msg);
        DimClient::sendCommandNB("DColl/Log", Msg);
        abort();
  }

  Terminating = true;

  // Make sure there was an exception; terminate is also called for an
  // attempt to rethrow when there is no suitable exception.
  type_info *Type = abi::__cxa_current_exception_type();
  if (Type != NULL) {
        int Status = -1;
        char *Demangled = NULL;

        Demangled = abi::__cxa_demangle(Type->name(), 0, 0, &Status);
        snprintf(Msg, sizeof(Msg), "Terminate() called after throwing an instance of '%s'", Status==0 ? Demangled : Type->name());
        free(Demangled);

        // If exception derived from std::exception, more information.
        try { __throw_exception_again; }
        catch (exception &E) {
          snprintf(Msg+strlen(Msg), sizeof(Msg)-strlen(Msg), " (what(): %s)", E.what());          
        }
        catch (...) { }
  }
  else snprintf(Msg, sizeof(Msg), "Terminate() called without an active exception");

  ThisServer->Message(FATAL, Msg);
}


// Translates DIMInfo to string (memory has to be freed by caller)
// Static method, cannot report memory allocation errors via Message() but returns NULL
char *EvidenceServer::ToString(DimInfo *Item) {

  char *Text;

  // Safety check
  if (Item->getSize() < 1) return NULL;

  // Message structure format handled
  if (strcmp(Item->getFormat(), "I:1;C") == 0) {
        struct Message *Msg = (struct Message *) Item->getData();
        if (asprintf(&Text, "%d %s", Msg->Severity, Msg->Text) == -1) return NULL;
        else return Text;
  }
  
  // Structure: print hex representation (3 characters per byte)  
  if (strlen(Item->getFormat()) != 1) {
    int Size = 3*Item->getSize()+1, N;
    if ((Text = (char *) malloc(Size)) == NULL) return NULL;
        
        char *CurrPos = Text;
        for (int i=0; i<Item->getSize(); i++) {
          N = snprintf(CurrPos, Size, "%02x ", *((char *) Item->getData() + i));
          if (N<0 || N>=Size) {
            free(Text);
                if (asprintf(&Text, "Structure length %d bytes, buffer overflow in ToString()", Item->getSize()) == -1) return NULL;
                else return Text;
          }
          Size -= N;
          CurrPos += N;
        } 
        return Text;
  }

  // String: terminating \0 is enforced
  if (toupper(*(Item->getFormat())) == 'C') {  
    *(Item->getString() + Item->getSize() - 1) = '\0'; 
        if (asprintf(&Text, "%s", Item->getString()) == -1) return NULL;
        return Text;
  }

  // Number array
  int Size;
  switch (toupper(*(Item->getFormat()))) {
    case 'I':
    case 'L': Size = sizeof(int);               break;
    case 'S': Size = sizeof(short);             break;
    case 'F': Size = sizeof(float);             break;
    case 'D': Size = sizeof(double);    break;
    case 'X': Size = sizeof(long long); break;
    default: return NULL;
  }

  int Max, Mem = Item->getSize()*Size*4+1;
  char *Pos;

  if ((Text = (char *) malloc(Mem)) == NULL) return NULL;

  *Text = '\0';
  for (int i=0; i<Item->getSize()/Size; i++) {
        Pos = Text+strlen(Text);
        Max = Mem-strlen(Text);

        switch (toupper(*(Item->getFormat()))) {
      case 'I':
      case 'L': snprintf(Pos, Max, "%d ", *((int *) Item->getData() + i));
                                break;
      case 'S': snprintf(Pos, Max, "%hd ", *((short *) Item->getData() + i));
                                break;
      case 'F': snprintf(Pos, Max, "%.5f ", *((float *) Item->getData() + i));
                                break;
      case 'D': snprintf(Pos, Max, "%.5f ", *((double *) Item->getData() + i));
                                break;
      case 'X': snprintf(Pos, Max, "%lld ", *((long long *) Item->getData() + i));
                                break;
        }
  }
  
  return Text;
}

// Checks if service contents indicates not available
bool EvidenceServer::ServiceOK(DimInfo *Item) {

  return !((Item->getSize() == strlen(NO_LINK)+1) &&  
          (memcmp(Item->getData(), NO_LINK, Item->getSize()) == 0));
}

bool EvidenceServer::ServiceOK(DimRpcInfo *Item) {

  return !((Item->getSize() == strlen(NO_LINK)+1) &&  
          (memcmp(Item->getData(), NO_LINK, Item->getSize()) == 0));
}

///////////////////////////
// EvidenceHistory Class //
///////////////////////////

// Organisaztion of history buffer
// F | T S D | T S D | 0 0 ......  | T S D | T S D | 0 -1
//
// F: Offset of oldest entry  T: Time  S: Size  D: Data
// F, T, S: int

// Marker for history buffer
const struct EvidenceHistory::Item EvidenceHistory::WrapMark = {0, -1, {}};
const struct EvidenceHistory::Item EvidenceHistory::EndMark = {0, 0, {}};

// Constructor
EvidenceHistory::EvidenceHistory(std::string Name):     Name(Name) {

  Buffer = NULL;
}

// Destructor
EvidenceHistory::~EvidenceHistory() {

  delete[] Buffer;
}

// Requests service history (returns true if data received OK)
bool EvidenceHistory::GetHistory() {

  DimRpcInfo R((char *) "ServiceHistory", NO_LINK);
  R.setData((char *) Name.c_str());

  // Check if data OK
  if (!EvidenceServer::ServiceOK(&R)) return false;
  if (R.getSize() == 0) return false;
  
  // Copy data to buffer
  delete[] Buffer;
  BufferSize = R.getSize();
  Buffer = new char [BufferSize];

  memcpy(Buffer, R.getData(), BufferSize);
  DataStart = Buffer + strlen(Buffer) + 1;
  Rewind();
  
  return true;
}

// Returns next item in history buffer
const struct EvidenceHistory::Item *EvidenceHistory::Next() {

  if (Buffer == NULL) return NULL;

  // Check for wrap around
  if (memcmp(Pointer, &WrapMark, sizeof(WrapMark)) == 0) Pointer = (struct Item *) (DataStart + sizeof(int));
  // Check if at end of ring buffer
  if (memcmp(Pointer, &EndMark, sizeof(EndMark)) == 0) return NULL;

  const struct Item *Ret = Pointer;
  Pointer = (struct Item *) ((char *) (Ret + 1) + Ret->Size);

  return Ret;
}

// Reset to start of buffer
void EvidenceHistory::Rewind() {

  if (Buffer != NULL) Pointer = (struct Item *) (DataStart + (*(int *) DataStart));
}

// Return DIM format string of service (NULL if no data)
char *EvidenceHistory::GetFormat() {

  return Buffer;
}