mirror of
https://github.com/mongodb/mongo.git
synced 2024-11-30 17:10:48 +01:00
105 lines
3.2 KiB
C++
105 lines
3.2 KiB
C++
// recstore.h
|
|
|
|
#pragma once
|
|
|
|
namespace mongo {
|
|
|
|
using boost::uint32_t;
|
|
using boost::uint64_t;
|
|
|
|
typedef uint64_t fileofs;
|
|
|
|
/* Current version supports only consistent record sizes within a store. */
|
|
|
|
class BasicRecStore {
|
|
struct RecStoreHeader {
|
|
uint32_t version;
|
|
uint32_t recsize;
|
|
uint64_t leof; // logical eof, actual file might be prealloc'd further
|
|
uint64_t firstDeleted; // 0 = no deleted recs
|
|
uint32_t cleanShutdown; // = clean
|
|
char reserved[8192-8-8-4-4-4]; // we want our records page-aligned in the file if they are a multiple of a page's size -- so we make this 8KB with that goal
|
|
RecStoreHeader() {
|
|
version = 65;
|
|
recsize = 0;
|
|
leof = sizeof(RecStoreHeader);
|
|
firstDeleted = 0;
|
|
cleanShutdown = 1;
|
|
memset(reserved, 0, sizeof(reserved));
|
|
}
|
|
};
|
|
|
|
public:
|
|
~BasicRecStore();
|
|
void init(const char *fn, unsigned recsize);
|
|
fileofs insert(const char *buf, unsigned len);
|
|
void update(fileofs o, const char *buf, unsigned len);
|
|
void remove(fileofs o, unsigned len);
|
|
void get(fileofs o, char *buf, unsigned len);
|
|
private:
|
|
|
|
void writeHeader();
|
|
fstream f;
|
|
fileofs len;
|
|
RecStoreHeader h; // h.reserved is wasteful here; fix later.
|
|
void write(fileofs ofs, const char *data, unsigned len) {
|
|
f.seekp((std::streamoff)ofs);
|
|
f.write(data, len);
|
|
massert("basicrecstore write io error", !f.bad());
|
|
}
|
|
public:
|
|
void flush() { f.flush(); }
|
|
};
|
|
|
|
/* --- implementation --- */
|
|
|
|
inline BasicRecStore::~BasicRecStore() {
|
|
h.cleanShutdown = 0;
|
|
if( f.is_open() )
|
|
writeHeader();
|
|
}
|
|
|
|
inline void BasicRecStore::writeHeader() {
|
|
write(0, (const char *) &h, 28); // update header in file for new leof
|
|
uassert("file io error in BasicRecStore [1]", !f.bad());
|
|
}
|
|
|
|
inline fileofs BasicRecStore::insert(const char *buf, unsigned reclen) {
|
|
if( h.firstDeleted ) {
|
|
uasserted("deleted not yet implemented recstoreinsert");
|
|
}
|
|
massert("bad len", reclen == h.recsize);
|
|
fileofs ofs = h.leof;
|
|
h.leof += reclen;
|
|
if( h.leof > len ) {
|
|
// grow the file. we grow quite a bit to avoid excessive file system fragmentations
|
|
len += (len / 8) + h.recsize;
|
|
uassert( "recstore file too big for 32 bit", len <= 0x7fffffff || sizeof(std::streamoff) > 4 );
|
|
write(len, "", 0);
|
|
}
|
|
writeHeader();
|
|
write(ofs, buf, reclen);
|
|
uassert("file io error in BasicRecStore [2]", !f.bad());
|
|
return ofs;
|
|
}
|
|
|
|
/* so far, it's ok to read or update a subset of a record */
|
|
|
|
inline void BasicRecStore::update(fileofs o, const char *buf, unsigned len) {
|
|
assert(o <= h.leof && o >= sizeof(RecStoreHeader));
|
|
write(o, buf, len);
|
|
}
|
|
|
|
inline void BasicRecStore::get(fileofs o, char *buf, unsigned len) {
|
|
assert(o <= h.leof && o >= sizeof(RecStoreHeader));
|
|
f.seekp((std::streamoff)o);
|
|
f.read(buf, len);
|
|
massert("basicrestore::get I/O error", !f.bad());
|
|
}
|
|
|
|
inline void BasicRecStore::remove(fileofs o, unsigned len) {
|
|
uasserted("not yet implemented recstoreremove");
|
|
}
|
|
|
|
}
|