portable_off_t Store::alloc()
{
STORE_ASSERT(m_state==Reading);
m_state=Writing;
portable_off_t pos;
if (m_head==0) // allocate new block
{
//printf("alloc: new block, pos=%lld\n",(long long)m_front);
if (portable_fseek(m_file,0,SEEK_END)==-1) // go to end of the file
{
fprintf(stderr,"Store::alloc: Error seeking to end of file: %s\n",strerror(errno));
exit(1);
}
#if USE_FTELL
pos = portable_ftell(m_file);
STORE_ASSERT( (pos & (BLOCK_SIZE-1))==0 );
m_front = pos + BLOCK_SIZE; // move front to end of this block
#else
m_cur = m_front;
pos = m_cur;
STORE_ASSERT( (pos & (BLOCK_SIZE-1))==0 );
m_front = pos + BLOCK_SIZE;
#endif
}
else // reuse freed block
{
//printf("alloc: reuse block: pos=%lld\n",(long long)m_head->pos);
Node *node = m_head;
pos = node->pos;
// point head to next free item
m_head = node->next;
delete node;
// move to start of the block
if (portable_fseek(m_file,pos,SEEK_SET)==-1)
{
fprintf(stderr,"Store::alloc: Error seeking to position %d: %s\n",
(int)pos,strerror(errno));
exit(1);
}
m_cur = pos;
STORE_ASSERT( (pos & (BLOCK_SIZE-1))==0 );
}
//printf("%x: Store::alloc\n",(int)pos);
return pos;
}
void Store::end()
{
STORE_ASSERT(m_state == Writing);
#if USE_FTELL
portable_off_t curPos = portable_ftell(m_file);
#else
portable_off_t curPos = m_cur;
#endif
int bytesInBlock = (int)(BLOCK_SIZE - (curPos & (BLOCK_SIZE - 1)));
//printf("%x: Store::end erasing %x bytes\n",(int)curPos&~(BLOCK_SIZE-1),bytesInBlock);
//printf("end: bytesInBlock=%x\n",bytesInBlock);
// zero out rest of the block
int i;
for (i = 0; i < bytesInBlock; i++) {
fputc(0, m_file);
}
m_state = Reading;
}
int Store::read(char *buf,uint size)
{
STORE_ASSERT(m_state==Reading);
//printf("%x: Store::read total=%d\n",(int)portable_ftell(m_file),size);
do
{
#if USE_FTELL
portable_off_t curPos = portable_ftell(m_file);
#else
portable_off_t curPos = m_cur;
#endif
int bytesInBlock = (int)(BLOCK_SIZE - BLOCK_POINTER_SIZE - (curPos & (BLOCK_SIZE-1)));
int bytesLeft = bytesInBlock<(int)size ? (int)size-bytesInBlock : 0;
int numBytes = size - bytesLeft;
//printf(" Store::read: pos=%x num=%d left=%d\n",(int)curPos,numBytes,bytesLeft);
if (numBytes>0)
{
//printf("%x: Store::read: %d out of %d bytes\n",(int)portable_ftell(m_file),numBytes,size);
if ((int)fread(buf,1,numBytes,m_file)!=numBytes)
{
fprintf(stderr,"Error reading from store: %s\n",strerror(errno));
exit(1);
}
m_cur+=numBytes;
m_reads++;
}
if (bytesLeft>0)
{
portable_off_t newPos;
// read offset of the next block
#if USE_FTELL
STORE_ASSERT(((portable_ftell(m_file)+BLOCK_POINTER_SIZE)&(BLOCK_SIZE-1))==0);
#else
STORE_ASSERT(((m_cur+BLOCK_POINTER_SIZE)&(BLOCK_SIZE-1))==0);
#endif
if (fread((char *)&newPos,BLOCK_POINTER_SIZE,1,m_file)!=1)
{
fprintf(stderr,"Error reading from store: %s\n",strerror(errno));
exit(1);
}
//printf("%x: Store::read: continue in next block, %d bytes to go\n",(int)newPos,bytesLeft);
//printf(" Store::read: next block=%x\n",(int)newPos);
STORE_ASSERT(newPos!=0);
STORE_ASSERT((newPos&(BLOCK_SIZE-1))==0);
curPos = newPos;
// move to next block
if (portable_fseek(m_file,curPos,SEEK_SET)==-1)
{
fprintf(stderr,"Store::read: Error seeking to position %d: %s\n",
(int)curPos,strerror(errno));
exit(1);
}
m_cur = curPos;
}
size-=numBytes;
buf+=numBytes;
}
while (size>0);
return size;
}
int Store::write(const char *buf,uint size)
{
STORE_ASSERT(m_state==Writing);
//printf("%x: Store::write\n",(int)portable_ftell(m_file));
do
{
#if USE_FTELL
portable_off_t curPos = portable_ftell(m_file);
#else
portable_off_t curPos = m_cur;
#endif
int bytesInBlock = (int)(BLOCK_SIZE - BLOCK_POINTER_SIZE - (curPos & (BLOCK_SIZE-1)));
int bytesLeft = bytesInBlock<(int)size ? (int)size-bytesInBlock : 0;
int numBytes = size - bytesLeft;
STORE_ASSERT(bytesInBlock>=0);
STORE_ASSERT(numBytes<=(int)(BLOCK_SIZE-BLOCK_POINTER_SIZE));
if (numBytes>0)
{
if ((int)fwrite(buf,1,numBytes,m_file)!=numBytes)
{
fprintf(stderr,"Error writing: %s\n",strerror(errno));
exit(1);
}
m_cur+=numBytes;
m_writes++;
}
if (bytesLeft>0) // still more bytes to write
{
#if USE_FTELL
STORE_ASSERT(((portable_ftell(m_file)+BLOCK_POINTER_SIZE)&(BLOCK_SIZE-1))==0);
#else
STORE_ASSERT(((m_cur+BLOCK_POINTER_SIZE)&(BLOCK_SIZE-1))==0);
#endif
// allocate new block
if (m_head==0) // no free blocks to reuse
{
//printf("%x: Store::write: new: pos=%x\n",(int)m_front,(int)portable_ftell(m_file));
// write pointer to next block
if (fwrite(&m_front,BLOCK_POINTER_SIZE,1,m_file)!=1)
{
fprintf(stderr,"Error writing to store: %s\n",strerror(errno));
exit(1);
}
m_cur+=BLOCK_POINTER_SIZE;
#if USE_FTELL
STORE_ASSERT(portable_ftell(m_file)==(curPos&~(BLOCK_SIZE-1))+BLOCK_SIZE);
#else
STORE_ASSERT(m_cur==(curPos&~(BLOCK_SIZE-1))+BLOCK_SIZE);
#endif
// move to next block
if (portable_fseek(m_file,0,SEEK_END)==-1) // go to end of the file
{
fprintf(stderr,"Store::alloc: Error seeking to end of file: %s\n",strerror(errno));
exit(1);
}
m_cur=m_front;
#if USE_FTELL
STORE_ASSERT(portable_ftell(m_file)==m_front);
#else
STORE_ASSERT(m_cur==m_front);
#endif
// move front to the next of the block
m_front+=BLOCK_SIZE;
}
else // reuse block from the free list
{
// write pointer to next block
if (fwrite(&m_head->pos,BLOCK_POINTER_SIZE,1,m_file)!=1)
{
fprintf(stderr,"Error writing to store: %s\n",strerror(errno));
exit(1);
}
Node *node = m_head;
portable_off_t pos = node->pos;
// point head to next free item
m_head = node->next;
delete node;
// move to start of the block
if (portable_fseek(m_file,pos,SEEK_SET)==-1)
{
fprintf(stderr,"Store::write: Error seeking to position %d: %s\n",
(int)pos,strerror(errno));
exit(1);
}
m_cur = pos;
//printf("%x: Store::write: reuse\n",(int)pos);
}
}
size-=numBytes;
buf+=numBytes;
}
while (size>0);
return size;
}
