source: Evidence/Evidence.cc @ 142

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

  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.
  - The Status service is published (special format, see below).
    It can be updated with the State() method. The text will also be logged.
  - If the severity of a State() call is FATAL, exit() will be called (with
    this severity, the call to State() 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
        
  All memory allocated by the non-static methods will be freed by the
  class destructor.
  
  Oliver Grimm, December 2009
 
\********************************************************************/

#include "Evidence.h"

bool EvidenceServer::ExitRequest = false;

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

  // Initialize
  Status = NULL;
  ConfigList = NULL;
  ConfigNum = 0;
  
  // Catch some signals
  signal(SIGQUIT, &SignalHandler);  // CTRL-Backspace
  signal(SIGTERM, &SignalHandler);  // Termination signal
  signal(SIGINT, &SignalHandler);   // CTRL-C
  signal(SIGHUP, &SignalHandler);   // Terminal closed
  
  // Create server name
  if (MakeString(&StatusName, "%s/Status", Name) == -1) {
    State(FATAL, "Could not generate service name, asprintf() failed");
  }
  
  // Start server
  Status = new DimService(StatusName, (char *) "Server started");

  start(Name);
  addExitHandler(this);
}

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

  free(StatusName);
  
  for (unsigned int i=0; i<ConfigNum; i++) {
        delete[] ConfigList[i].Name;
        delete[] ConfigList[i].Value;
  }
  free(ConfigList);
}

// DIM exit handler
void EvidenceServer::exitHandler(int Code) {
  State(INFO, "Server stopped (DIM exit code %d)", Code);
  exit(EXIT_SUCCESS);
}

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

// Set status of server
//
// The message format is special: after the string-terminating '\0' the Severity 
// is given, terminated by another '\0'  The buffer for the DIM service must have
// the same lifetime as the DIM service. If Severity is FATAL, exit() will be invoked.
void EvidenceServer::State(StateType Severity, const char *Format, ...) {

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

  snprintf(TBuf, sizeof(TBuf), "%s (%s): %s", StatusName, StateString[Severity], Tmp);
  snprintf(SBuf, sizeof(SBuf), "%s\0%d", Tmp);

  if (Tmp != ErrorString) free(Tmp);
  
  // Send message to console and log file
  printf("%s\n", TBuf);
  if (Severity != INFO) DimClient::sendCommand("DColl/Log", TBuf);

  // Update DIM status service (including severity encoding)
  if (Status != NULL) Status->updateService(SBuf, strlen(SBuf)+2);

  // Terminate if message type is fatal
  if (Severity == FATAL) exit(EXIT_FAILURE);
}

// Get configuration data (program terminates if data is missing)
//
// The memory allocated by all calls to this function will be freed by
// the destructor.
char* EvidenceServer::GetConfig(const char *Item) {
  
  // Determine configuration file update time
  DimCurrentInfo ModifyTime("Config/ModifyTime", 0);
  int Time = ModifyTime.getInt(), ItemNo = -1;
  
  // Check if configuration request already in list
  for (int i=0; i<ConfigNum; i++) {
    if (strcmp(ConfigList[i].Name, Item) == 0) {
          // Return original value if still up to date
          if (ConfigList[i].Time >= Time) return ConfigList[i].Value;

          // Otherwise, free memory of old value
          delete[] ConfigList[i].Name;
          delete[] ConfigList[i].Value;   
          ItemNo = i;
          break;
        }
  } 
  
  // Make configuration request
  DimRpcInfo Config((char *) "ConfigRequest", (char *) "");
  Config.setData((char *) Item);

  // Terminate if not successful
  if (strlen(Config.getString()) == 0) {
    State(FATAL, "Missing configuration data '%s'", Item);
  }

  // Enlarge memory to hold new pointer if necessary
  if (ItemNo == -1) {
        void *N = realloc(ConfigList, sizeof(struct ConfigItem)*(++ConfigNum));
        if (N == NULL) {
          State(WARN, "Could not realloc() memory for configuration, will lose memory (%s)", strerror(errno));
          ConfigNum--;  
        }
        else ConfigList = (struct ConfigItem *) N;
        
        ItemNo = ConfigNum-1;
  }
  
  // Allocate memory for strings, and copy data to this memory
  ConfigList[ItemNo].Value = new char [strlen(Config.getString())+1];
  ConfigList[ItemNo].Name = new char [strlen(Item)+1];
  strcpy(ConfigList[ItemNo].Name, Item);
  strcpy(ConfigList[ItemNo].Value, Config.getString());

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


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

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

  EvidenceServer::ExitRequest = true;
}

// Translates DIMInfo to string (memory has to be freed by caller)
// No DIM structures are supported (only a single number or string is converted)
char *EvidenceServer::ToString(DimInfo *Item) {

  char *Text;
  
  if (strlen(Item->getFormat()) != 1) return NULL;
  
  switch (*(Item->getFormat())) {
    case 'I':  MakeString(&Text, "%d", Item->getInt());   break;
    case 'C':  MakeString(&Text, "%s", Item->getString());   break;
    case 'S':  MakeString(&Text, "%hd", Item->getShort());   break;
    case 'F':  MakeString(&Text, "%.5f", Item->getFloat());   break;
    case 'D':  MakeString(&Text, "%.5f", Item->getDouble());   break;
    case 'X':  MakeString(&Text, "%lld", Item->getLonglong());   break;
    default: return NULL;
  }

  return Text;
}

//
// Generate string with vasprintf()
//
// The pointer will be set to NULL in case of error, so can always safely passed to free().
// In case vasprintf() is not available on a particular system, the functionality can
// be manually implemented in this routine. 
//
int EvidenceServer::MakeString(char **Pointer, const char *Format, ...) {

  int Ret;
  va_list ArgumentPointer;  

  va_start(ArgumentPointer, Format);  
  if ((Ret = vasprintf(Pointer, Format, ArgumentPointer)) == -1) Pointer = NULL;
  va_end(ArgumentPointer);
  
  return Ret;
}