GDBMS_for_documentation/file_semaphore.cpp

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#include "maininclude.h"
#include "listi.h"
#include "settings.h"
#include "hash_table.h"
#include "tr_twin_ht.h"
#include "file_semaphore.h"
#include "some_functions.h"
#include "initial_mode_commands.h"
#include "session_mode_commands.h"
#include "transaction_mode_commands.h"
#include "transaction_mode_commands_types.h"
#include "transaction_mode_commands_nodes.h"
#include "transaction_mode_commands_edges.h"
#include "transaction_mode_commands_find.h"
#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/shm.h>
#define SHMSZ     2048
using namespace std;
file_semaphore::file_semaphore(char* path_to_file)
{
  
  this->filepath+=path_to_file;
  this->resid=0;
}
void file_semaphore::getResource()
{
  /*
  one_fs:
  srand ( time(NULL) );
  if(!FileExists(this->filepath)){
    //nyama takyv file. tryabva da syzdadem file-a
    char *buf33=new char[1000];
    buf33[0]=0;
    strcat(buf33, MAINFOLDER);
    strcat(buf33, filepath.c_str());
    two_fs:
    fp1=fopen(buf33, "w");
    
    if(!fp1){
      usleep(200000+ rand()%800000);
      goto two_fs;
    }
    
    
    int i1=rand()%400+1;
    this->resid=i1;
    fprintf(fp1, "%d", i1);
    fclose(fp1);
    delete buf33;
    
    
  }else{
      
      usleep(200000+ rand()%800000);
      goto one_fs;
    }
    
    
    */
    srand ( time(NULL) );
    char c;
    int shmid;
    key_t key;
    char *shm, *s;

    /*
     * We'll name our shared memory segment
     * "".
     */
    key = hshcode(this->filepath);

    /*
     * Create the segment or locate it.
     */
    if ((shmid = shmget(key, SHMSZ, IPC_CREAT | 0666)) < 0) {
        
        exit(1);
    }

    /*
     * Now we attach the segment to our data space.
     */
    if ((shm = shmat(shmid, NULL, 0)) == (char *) -1) {
        
        exit(1);
    }
    /* Inizializirane na shared memory, ako e syzdadena za 1 pyt*/
    if(*shm!='*'){
      *shm='*';
      *(shm+1)='1';
      s=shm+1;
      while(s-shm<SHMSZ){
        *s++=0;
        
        
      }
      *(shm+1)=0;
    }
    //4akane da se osvobodi pametta ako nqkoj pi6e v neq
    while(*(shm+1)=='1'){
      usleep(200000+ rand()%800000);
      
    }
    //zaemame si pametta
    *(shm+1)='1';
    int *t=shm;
    this->resid=getpid();
    
    
    //narejdame se na opa6ka
    t++;
    while(*t!=0&&(char *)t<shm+SHMSZ*sizeof(int)){
      t++;
      
    }
    *t=this->resid;
    *(shm+1)=0;
    //4akame si reda na opa6kata
    while(*(((int *)shm)+1)!=this->resid){
      usleep(200000+ rand()%800000);
    }
    
   
    
    return;
}
void file_semaphore::freeResource()
{
  /*
  char *buf33=new char[1000];
    buf33[0]=0;
    strcat(buf33, MAINFOLDER);
    strcat(buf33, filepath.c_str());
  fp1=fopen(buf33, "r");
  if(fp1){
    int t;
    fscanf(fp1, "%d", &t);
    fclose(fp1);
    if(t==this->resid)
      remove(filepath.c_str());
  }
  delete buf33;
  */
    srand ( time(NULL) );
    char c;
    int shmid;
    key_t key;
    char *shm, *s;

    /*
     * We'll name our shared memory segment
     * "".
     */
    key = hshcode(this->filepath);

    /*
     * Create the segment.
     */
    if ((shmid = shmget(key, SHMSZ, IPC_CREAT | 0666)) < 0) {
        
        exit(1);
    }

    /*
     * Now we attach the segment to our data space.
     */
    if ((shm = shmat(shmid, NULL, 0)) == (char *) -1) {
        
        exit(1);
    }
    //4akame nqkoj da se zapi6e na opa6kata, ako q e zael
    while(*(shm+1)=='1'){
      usleep(50000+ rand()%500000);
      
    }
    //zaemame si pametta
    *(shm+1)='1';
    int *t=shm;
    t++;
    int *t1=t+1;
    //osvobojdavame opa6kata
    while(*t1||*t){
      *t=*t1;
      t++;
      t1++;
      
    }
    
    //osvobojdavame si pametta
    *(shm+1)=0;
    return;
  
}
file_semaphore::~file_semaphore()
{
  /*
  if(fp1)
    fclose(fp1);
  */
}