complete persistensce storage

temp.c

@@ -21,41 +21,51 @@ pthread_t tid;
 pthread_t writerthreads[100],readerthreads[100];
 int readercount = 0;
 
-int modulus(char *num, int size, int divisor) {
-  int rem = 0;
+unsigned modulus( unsigned char *num, size_t size, unsigned divisor) {
+  unsigned rem = 0;
   
   while (size-- > 0) {
-    rem = ((UCHAR_MAX + 1)*rem + *num) % divisor;
+    rem = ((UCHAR_MAX + 1ULL)*rem + *num) % divisor;
     num++;
   }
   return rem;
 }
-void file_del(off_t offset, char *key)
+void file_del( char *key)
 {   
     int index=modulus(key,256,setSize);
     fflush(stdout);
     int length=0;
     sem_wait(&mutex[index]);
     char blankspace[512];
-     char ch;
-    int k=-1;
-    lseek(fds[index], offset, SEEK_SET);
-    while(read(fds[index], &ch,sizeof(ch))!=-1 && ch!='\n')
+    memset(blankspace,0,512);
+     char *line;
+     char temp[514];
+    size_t len=0;
+    off_t position=0;
+    FILE *fp=fdopen(fds[index],"rb+");
+    while ((getline(&line, &len, fp)) != -1)
     {
-        length++;
+        memcpy(temp,line,strlen(line)-1);
+        char *fkey=strtok(line,":");
+        char *fvalue=strtok(NULL,":");
+        
+        if(strcmp(key,fkey)==0){
+            lseek(fds[index],position,SEEK_SET);
+            write(fds[index],blankspace,strlen(temp));
+            puts(temp);
+            break;
+        }
+        position=ftell(fp);
+        
     }
-    printf("length %d",length);
-    memset(blankspace, 0, length);
-    lseek(fds[index], offset, SEEK_SET);
-    write(fds[index], blankspace, length);
     sem_post(&mutex[index]);
     
 }
-void file_get(char *key, char *value)
+int file_get(char *key, char *value)
 {   
     /* Gets the value stored at offset */
     /* Does not depend on key argument */
-
+    int found =0;
     int index=modulus(key,256,setSize);
     sem_wait(&readerLocks[index]);
     readCounters[index]+=1;
@@ -63,20 +73,15 @@ void file_get(char *key, char *value)
         sem_wait(&mutex[index]);
     sem_post(&readerLocks[index]);
     char *line;
-    //FILE *fp =fdopen(fds[index],"r+");
-   // fseek(fp, offset,SEEK_SET);
     size_t len=0;
-    
-    char ch;
-    int k=-1;
-   
-    FILE *fp=fdopen(fds[index],"r+");
+    FILE *fp=fdopen(fds[index],"rb+");
     while ((getline(&line, &len, fp)) != -1)
     {
         char *fkey=strtok(line,":");
         char *fvalue=strtok(NULL,":");
         if(strcmp(key,fkey)==0){
-            memcpy(value,fvalue,strlen(fvalue));
+            memcpy(value,fvalue,strlen(fvalue)-1);
+            found=1;
             break;
         }
         
@@ -88,31 +93,57 @@ void file_get(char *key, char *value)
         sem_post(&mutex[index]);
     }
     sem_post(&readerLocks[index]);
+    return found;
 }
 
-off_t file_put(char *key,char *value) {
-
-    int index=modulus(key,256,setSize);
-    int bytes, rembytes, i;
+off_t file_put(char *key,char *value)
+ {
+     /*
+        if found then ask the offset where it is present and if the value noy matches with the present value ,update the given line
+        if not present then search for empty line and insert there!
+     */
+    unsigned int index=modulus(key,256,setSize);
     off_t position;
-
-    sem_wait(&mutex[index]);
+    //sem_wait(&mutex[index]);
     printf("[Write to File: %d]\n",index);
-    position = lseek(fds[index], 0, SEEK_END);
-    char line [514];
-    snprintf(line, sizeof(line),"%s:%s\n",key,value);
-    if(write(fds[index], line, strlen(line))<0)
+    char *line;
+    char lin[514];
+    size_t len=0;
+    FILE *fp=fdopen(fds[index],"rb+");
+    position=ftell(fp);
+    while ((getline(&line, &len, fp)) != -1)
+    {
+        char *fkey=strtok(line,":"); 
+        char *fvalue=strtok(NULL,":");
+        if(strcmp(key,fkey)==0){
+            if(strcmp(value,strtok(fvalue,"\n"))==0)
+            {
+                printf("(%s)(%s)\n",fkey,key);
+               ///everything same then why insert?
+               return 0;
+            }
+            else
+            {
+                printf("key:(%s)(%s)\n",fkey,key);
+                printf("value:(%s)(%s)\n",fvalue,value);
+                fflush(stdout);
+                fseek(fp,position,SEEK_SET);
+                snprintf(lin, sizeof(lin),"%s:%s\n",key,value);
+                if(fputs(lin,fp)<0)
+                    printf("\n[unable to perform file_put]\n");
+                return 0;
+            }
+        }
+        position=ftell(fp); 
+    }     
+    snprintf(lin, sizeof(lin),"%s:%s\n",key,value);
+    if(write(fds[index], lin, strlen(lin))<0)
         printf("\n[unable to perform file_put]\n");
-    sem_post(&mutex[index]);
-
-    return position;
-}
-void file_search(char *key,char *value)
-{
-    int index=modulus(key,256,setSize);
     
 
+   // sem_post(&mutex[index]);
 
+    return position;
 }
 int main()
 {
@@ -125,7 +156,7 @@ int main()
     */
     int n2=0;
     char prevkey[256]="24";
-    char key[256]="24sadasdasdasdasdsad";
+    char key[256]="25";
     char value[256]="value2";
     off_t offset;
     bzero(key+strlen(key),sizeof(key)-strlen(key));
@@ -148,12 +179,10 @@ int main()
         sem_init(&mutex[i],0,1);
         readCounters[i]=0;
     }
-    
-
-    offset = file_put(prevkey, "value1");
-    offset = file_put(key, value);
-    file_get(prevkey, value);   // Doesnot depend on key arg, returns key and value at offset 0
-    printf("%s\n", value);
-    //file_del(offset, prevkey);
+    //offset = file_put("24", "value245");
+    //offset = file_put("40", "value28");
+    //file_get(prevkey, value);   // Doesnot depend on key arg, returns key and value at offset 0
+    //printf("(%s)", value);
+    file_del("29");
 
 }