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-rw-r--r--src/store.cpp392
1 files changed, 392 insertions, 0 deletions
diff --git a/src/store.cpp b/src/store.cpp
new file mode 100644
index 0000000..f1f24cd
--- /dev/null
+++ b/src/store.cpp
@@ -0,0 +1,392 @@
+#include "store.h"
+
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <errno.h>
+#include <string.h>
+#include <assert.h>
+
+#define BLOCK_SIZE 512 // should be >8 and a multiple of 8
+#define BLOCK_POINTER_SIZE sizeof(off_t)
+
+
+#define ASSERTS_ENABLED
+
+#ifdef ASSERTS_ENABLED
+#define STORE_ASSERT(x) assert(x)
+#else
+#define STORE_ASSERT(x)
+#endif
+
+#ifdef _WIN32 // TODO: add 64bit support using _fseeki64 and _ftelli64 (studio 2003+ req)
+#define fseeko fseek
+#define ftello ftell
+#endif
+
+
+//------------------------------------------------------------------------------------
+
+Store::Store()
+{
+ m_file = 0;
+ m_front = 0;
+ m_head = 0;
+ m_state = Init;
+ m_reads = 0;
+ m_writes = 0;
+}
+
+Store::~Store()
+{
+ if (m_file) fclose(m_file);
+
+ // clean up free list
+ while (m_head)
+ {
+ Node *node = m_head;
+ m_head = node->next;
+ delete node;
+ }
+}
+
+int Store::open(const char *name)
+{
+ int i;
+ STORE_ASSERT(m_state==Init);
+ if (m_file) return 0; // already open
+ m_file = fopen(name,"w+b");
+ if (m_file==0) return -1;
+
+ // first block serves as header, so offset=0 can be used as the end of the list.
+ for (i=0;i<BLOCK_SIZE/8;i++)
+ {
+ fputc('D',m_file);
+ fputc('O',m_file);
+ fputc('X',m_file);
+ fputc('Y',m_file);
+ fputc('G',m_file);
+ fputc('E',m_file);
+ fputc('N',m_file);
+ fputc(0,m_file);
+ }
+ m_front = BLOCK_SIZE;
+ m_head = 0;
+ m_state = Reading;
+ return 0;
+}
+
+void Store::close()
+{
+ if (m_file) fclose(m_file);
+ m_file=0;
+ m_state = Init;
+}
+
+off_t Store::alloc()
+{
+ STORE_ASSERT(m_state==Reading);
+ m_state=Writing;
+ off_t pos;
+ if (m_head==0) // allocate new block
+ {
+ //printf("alloc: new block\n");
+ if (fseeko(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);
+ }
+ pos = ftello(m_file);
+ STORE_ASSERT( (pos & (BLOCK_SIZE-1))==0 );
+ m_front = pos + BLOCK_SIZE; // move front to end of this block
+ }
+ else // reuse freed block
+ {
+ //printf("alloc: reuse block: m_head=%d\n",(int)m_head);
+ 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 (fseeko(m_file,pos,SEEK_SET)==-1)
+ {
+ fprintf(stderr,"Store::alloc: Error seeking to position %d: %s\n",
+ (int)pos,strerror(errno));
+ exit(1);
+ }
+ STORE_ASSERT( (pos & (BLOCK_SIZE-1))==0 );
+ }
+ //printf("%x: Store::alloc\n",(int)pos);
+ return pos;
+}
+
+int Store::write(const char *buf,uint size)
+{
+ STORE_ASSERT(m_state==Writing);
+ //printf("%x: Store::write\n",(int)ftello(m_file));
+ do
+ {
+ off_t curPos = ftello(m_file);
+ int bytesInBlock = 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_writes++;
+ }
+ if (bytesLeft>0) // still more bytes to write
+ {
+ STORE_ASSERT(((ftello(m_file)+BLOCK_POINTER_SIZE)&(BLOCK_SIZE-1))==0);
+ // allocate new block
+ if (m_head==0) // no free blocks to reuse
+ {
+ //printf("%x: Store::write: new: pos=%x\n",(int)m_front,(int)ftello(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);
+ }
+ STORE_ASSERT(ftello(m_file)==(curPos&~(BLOCK_SIZE-1))+BLOCK_SIZE);
+
+ // move to next block
+ if (fseeko(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);
+ }
+ STORE_ASSERT(ftello(m_file)==m_front);
+ // 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;
+ off_t pos = node->pos;
+ // point head to next free item
+ m_head = node->next;
+ delete node;
+ // move to start of the block
+ if (fseeko(m_file,pos,SEEK_SET)==-1)
+ {
+ fprintf(stderr,"Store::write: Error seeking to position %d: %s\n",
+ (int)pos,strerror(errno));
+ exit(1);
+ }
+ //printf("%x: Store::write: reuse\n",(int)pos);
+ }
+ }
+ size-=numBytes;
+ buf+=numBytes;
+ }
+ while (size>0);
+ return size;
+}
+
+void Store::end()
+{
+ STORE_ASSERT(m_state==Writing);
+ off_t curPos = ftello(m_file);
+ int bytesInBlock = 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;
+}
+
+void Store::release(off_t pos)
+{
+ STORE_ASSERT(m_state==Reading);
+ //printf("%x: Store::release\n",(int)pos);
+ STORE_ASSERT(pos>0 && (pos & (BLOCK_SIZE-1))==0);
+ // goto end of the block
+ off_t cur = pos, next;
+ while (1)
+ {
+ // add new node to the free list
+ Node *node = new Node;
+ node->next = m_head;
+ node->pos = cur;
+
+ m_head = node;
+ // goto the end of cur block
+ if (fseeko(m_file,cur+BLOCK_SIZE-BLOCK_POINTER_SIZE,SEEK_SET)==-1)
+ {
+ fprintf(stderr,"Store::release: Error seeking to position %d: %s\n",
+ (int)(cur+BLOCK_SIZE-BLOCK_POINTER_SIZE),strerror(errno));
+ exit(1);
+ }
+ // read pointer to next block
+ if (fread(&next,BLOCK_POINTER_SIZE,1,m_file)!=1)
+ {
+ fprintf(stderr,"Store::release: Error reading from store: %s\n",strerror(errno));
+ exit(1);
+ }
+ if (next==0) break; // found end of list -> cur is last element
+ STORE_ASSERT((next & (BLOCK_SIZE-1))==0);
+ cur = next;
+ //printf("%x: Store::release\n",(int)cur);
+ }
+}
+
+void Store::seek(off_t pos)
+{
+ STORE_ASSERT(m_state==Reading);
+ //printf("%x: Store::seek\n",(int)pos);
+ if (fseeko(m_file,pos,SEEK_SET)==-1)
+ {
+ fprintf(stderr,"Store::seek: Error seeking to position %d: %s\n",
+ (int)pos,strerror(errno));
+ exit(1);
+ }
+ STORE_ASSERT((pos&(BLOCK_SIZE-1))==0);
+}
+
+int Store::read(char *buf,uint size)
+{
+ STORE_ASSERT(m_state==Reading);
+ //printf("%x: Store::read total=%d\n",(int)ftello(m_file),size);
+ do
+ {
+ off_t curPos = ftello(m_file);
+ int bytesInBlock = 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)ftello(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_reads++;
+ }
+ if (bytesLeft>0)
+ {
+ off_t newPos;
+ // read offset of the next block
+ STORE_ASSERT(((ftello(m_file)+BLOCK_POINTER_SIZE)&(BLOCK_SIZE-1))==0);
+ 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 (fseeko(m_file,curPos,SEEK_SET)==-1)
+ {
+ fprintf(stderr,"Store::read: Error seeking to position %d: %s\n",
+ (int)curPos,strerror(errno));
+ exit(1);
+ }
+ }
+
+ size-=numBytes;
+ buf+=numBytes;
+ }
+ while (size>0);
+ return size;
+}
+
+void Store::printFreeList()
+{
+ printf("FreeList: ");
+ off_t pos = m_head->pos;
+ while (pos)
+ {
+ printf("%x ",(int)pos);
+ m_head = m_head->next;
+ }
+ printf("\n");
+}
+
+void Store::printStats()
+{
+ printf("ObjStore: block size %d bytes, total size %ld blocks, wrote %d blocks, read %d blocks\n",
+ BLOCK_SIZE,(long)(m_front/BLOCK_SIZE),m_reads,m_writes);
+}
+
+#ifdef STORE_TEST
+
+int main()
+{
+ printf("sizeof(off_t)=%d\n",(int)sizeof(off_t));
+ Store s;
+ if (s.open("test.db")==0)
+ {
+ const char *str1 = "This is a test message... ";
+ const char *str2 = "Another message. ";
+
+ int i,j;
+ for (j=0;j<5;j++)
+ {
+ char buf[100];
+
+ off_t handle = s.alloc();
+ for (i=0;i<1000000000;i++)
+ {
+ s.write(str1,strlen(str1)+1);
+ }
+ s.end();
+ off_t handle2 = s.alloc();
+ for (i=0;i<10;i++)
+ {
+ s.write(str2,strlen(str2)+1);
+ }
+ s.end();
+
+ s.seek(handle);
+ for (i=0;i<3;i++)
+ {
+ s.read(buf,strlen(str1)+1);
+ printf("i=%d Read: %s\n",i,buf);
+ }
+
+ s.release(handle);
+
+ s.seek(handle2);
+ for (i=0;i<3;i++)
+ {
+ s.read(buf,strlen(str2)+1);
+ printf("i=%d Read: %s\n",i,buf);
+ }
+
+ s.release(handle2);
+ }
+
+ s.close();
+ }
+ else
+ {
+ printf("Open failed! %s\n",strerror(errno));
+ }
+}
+
+#endif
+
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