code for file

temp.c

+#include<semaphore.h>
 #include<stdio.h>
-#include <string.h>
-#include <stdlib.h>
-#include "KVMessageFormat.h"
-struct message* get(char m,char *key)
-{
-    if(!m || key==NULL )
-    {
-        printf("Invalid parameters in get()");
-        return NULL;
-    }
-    struct message *request= malloc(sizeof(struct message));
-    request->status=m;
-    memcpy(request->key,key,256); //copied the complete key
-    if(strlen(request->key)<256)
-    {
-        request->key[strlen(request->key)]='\0';
+#include<stdlib.h>
+#include<unistd.h>
+#include<pthread.h>
+#include <stdint.h>
+#include <limits.h>
+#include<fcntl.h> 
+#include<unistd.h>
+#include<string.h>
+#include<sys/stat.h>
+#include <sys/types.h>
+
+int *fds;
+int setSize=2;
+int *readCounters;
+sem_t *mutex;
+sem_t *readerLocks;
+sem_t x,y;
+pthread_t tid;
+pthread_t writerthreads[100],readerthreads[100];
+int readercount = 0;
+int modulus(char *num, int size, int divisor) {
+  int rem = 0;
+ 
+  while (size-- > 0) {
+    rem = ((UCHAR_MAX + 1)*rem + *num) % divisor;
+    num++;
   }
-    request->value[0]='\0';
-    return request;
+  return rem;
 }
-struct message* put(char m,char *key,char *value)
+void file_del(char *key)
 {   
-    if(!m || (key==NULL && value==NULL))
+    int index=modulus(key,256,setSize);
+    sem_wait(&mutex[index]);
+    FILE * fp;
+    char * line = NULL;
+    size_t len = 0;
+    int read;
+
+    fp = fdopen(fds[index], "a+");
+    if (fp == NULL)
+       printf("\n[Invalid file]\n");
+    int position=0;
+    while ((read = getline(&line, &len, fp)) != -1)
     {
-        printf("Invalid parameters in put()");
-        return NULL;
-    }
         
-    struct message *request= malloc(sizeof(struct message));
-    request->status=m;
-    memcpy(request->key,key,256); //copied the complete key
-    if(strlen(request->key)<256)
+        if(strstr(line,key)!=NULL && strstr(strstr(line,key),":")!=NULL)
         {
-        request->key[strlen(request->key)]='\0';
+            
+            fseek(fp,position,SEEK_SET);
+           
+            
+            break;
+        }
+        else
+        {
+            position+=len;
         }
         
-    memcpy(request->value,value,256); //copied the complete value
-    if(strlen(request->key)<256) //to pad with \0
+    }
+   //fclose(fp);
+    if (line)
+        free(line);
+    sem_wait(&readerLocks[index]);
+    readercount--;
+    if(readercount==0)
     {
-        request->key[strlen(request->value)]='\0';
+        sem_post(&mutex[index]);
     }
+    sem_post(&readerLocks[index]);
+}
+void file_get(char *key,char *value)
+{   
     
-    return request;
+    int index=modulus(key,256,setSize);
+    sem_wait(&readerLocks[index]);
+    readCounters[index]++;
+    if(readCounters[index]==1)
+        sem_wait(&mutex[index]);
+    sem_post(&readerLocks[index]);
+    FILE * fp;
+    char * line = NULL;
+    size_t len = 0;
+    int read;
 
-}
-struct message *del(char m,char *key){
-    if(!m || key==NULL )
+    fp = fdopen(fds[index], "r");
+    if (fp == NULL)
+       printf("\n[Invalid file]\n");
+
+    while ((read = getline(&line, &len, fp)) != -1)
+    {
+        if(strstr(line,key)!=NULL && strstr(strstr(line,key),":")!=NULL)
         {
-        printf("Invalid parameters in del()");
-        return NULL;
+            snprintf(value,sizeof((strchr(line,':')+1)),"%s",(strchr(line,':')+1));
         }   
-    struct message *request= malloc(sizeof(struct message));
-    request->status=m;
-    memcpy(request->key,key,256); //copied the complete key
-    if(strlen(request->key)<256)
+    }
+    fclose(fp);
+    if (line)
+        free(line);
+    sem_wait(&readerLocks[index]);
+    readercount--;
+    if(readercount==0)
     {
-        request->key[strlen(request->key)]='\0';
+        sem_post(&mutex[index]);
     }
-    request->value[0]='\0';
-    return request;
+    sem_post(&readerLocks[index]);
 }
-
-struct message *request(char status,char* key,char* value)
+void file_put(char *key,char *value)
 {
-      if(!status ||(key==NULL && value==NULL) )
+    int index=modulus(key,256,setSize);
+    sem_wait(&mutex[index]);
+    printf("\n[Write to File: %d]\n",index);
+    char line[514];
+    int i=0;
+    for(i=0;i<256;i++)
     {
-        printf("Invalid parameters in request()");
-        return NULL;
+        if(key[i]!='\0')
+        {
+            line[i]=key[i];
         }
-    struct message *requestMessage= malloc(sizeof(struct message));
-    requestMessage->status=status;
-
-    memcpy(requestMessage->key,key,256); //copied the complete key
-
-    if(strlen(requestMessage->key)<256)
+        else
         {
-        requestMessage->key[strlen(requestMessage->key)]='\0';
+            break;
         }    
-    if(value!=NULL)
+    }
+    int k=0;
+    line[i++]=':';
+    for(;i<512;i++)
+    {
+       if(value[k]!='\0')
         {
-        memcpy(requestMessage->value,value,256); //copied the complete value
+            line[i]=value[k++];
         }
-   
-    if(strlen(requestMessage->value)<256) //to pad with \0
+        else
         {
-        requestMessage->value[strlen(requestMessage->value)]='\0';
+            break;
         }    
-    printf("[Message Generated at Client]\n[[Status:%c]\n[Key:%s]\n[Value:%s]]",requestMessage->status,requestMessage->key,requestMessage->value);
-    return requestMessage;
+    }
+    line[i]='\n';
+    if(write(fds[index],line,strlen(line))<0)
+    {
+        printf("\n[Unable to Write to File]\n");
+    }
+    
+    sem_post(&mutex[index]);
 }
-void main()
+
+
+int main()
 {
-    char message[256];
-    for(int i=0;i<30;i++)
+    /*
+        define the array of file descriptors  depending on the prefix 
+        define the array of readCount as well as the semaphore (read x and write y) for the same
+        PUT,DEL would use write lock 
+        GET would use read lock
+        each write should return the line number
+
+    */
+    int n2=0;
+    char key[256]="24";
+    char value[256]="value";
+    fds=(int *)malloc(sizeof(int)*setSize);
+    readCounters=(int *)malloc(sizeof(int)*setSize);
+    readerLocks=(sem_t *)malloc(sizeof(sem_t)*setSize);
+    mutex=(sem_t *)malloc(sizeof(sem_t)*setSize);
+    int i=0;
+    char fileName[setSize+20];
+    for(i=0;i<setSize;i++)
+    {
+        snprintf(fileName,sizeof(fileName),"File%d.txt",i);
+        fds[i]=open(fileName, O_CREAT|O_RDWR|O_APPEND,S_IRWXU);
+        if(fds[i]<0)
         {
-        message[i]='a';
+            printf("\n[Unable to Open File%d.txt]\n",i);
         }
-    message[sizeof(message)]='\0';
-    request('2',message,message);   
-    char c ='2';
-    int status=(int)c;
-    
-    printf("%d",status);
+        sem_init(&readerLocks[i],0,1);
+        sem_init(&mutex[i],0,1);
+        readCounters[i]=0;
+    }
+    //file_put(key,value);
+    value[0]='\0';
+   // file_get(key,value);
+   /*  for(i=0;i<setSize-1;i++)
+    {
+        close(fds[i]);
+    } */
+   // printf("main vala hai ye!!");
+  //  puts(value);
+   file_del(key);
+    /*
+    printf("%u",modulus(key,256,3));
+    //scanf("%d",&n2);
+    printf("\n");
+    int n1[n2];
+    sem_init(&x,0,1);
+    sem_init(&y,0,1);
+    for(i=0;i<n2;i++)
+    {
+        pthread_create(&writerthreads[i],NULL,reader,NULL);
+        pthread_create(&readerthreads[i],NULL,writer,NULL);
+    }
+    for(i=0;i<n2;i++)
+    {
+        pthread_join(writerthreads[i],NULL);
+        pthread_join(readerthreads[i],NULL);
+    }
+    */
 
-    //creating a message
 }