*
* Backup data is stored in a collection of objects, which are grouped together
* into segments for storage purposes. This implementation of the object store
- * is built on top of libtar, and represents segments as TAR files and objects
- * as files within them. */
+ * represents segments as TAR files and objects as files within them. */
#ifndef _LBS_STORE_H
#define _LBS_STORE_H
#include <stdint.h>
-#include <libtar.h>
#include <list>
#include <map>
#include <sstream>
#include "sha1.h"
+#include "ref.h"
class LbsObject;
std::string getError() const { return error; }
};
+/* Simplified TAR header--we only need to store regular files, don't need to
+ * handle long filenames, etc. */
+static const int TAR_BLOCK_SIZE = 512;
+
+struct tar_header
+{
+ char name[100];
+ char mode[8];
+ char uid[8];
+ char gid[8];
+ char size[12];
+ char mtime[12];
+ char chksum[8];
+ char typeflag;
+ char linkname[100];
+ char magic[8];
+ char uname[32];
+ char gname[32];
+ char devmajor[8];
+ char devminor[8];
+ char prefix[155];
+ char padding[12];
+};
+
/* A simple wrapper around a single TAR file to represent a segment. Objects
* may only be written out all at once, since the tar header must be written
* first; incremental writing is not supported. */
Tarfile(const std::string &path, const std::string &segment);
~Tarfile();
+ int spawn_filter(int fd_out);
void write_object(int id, const char *data, size_t len);
// Return an estimate of the size of the file.
- size_t size_estimate() { return size; }
+ size_t size_estimate();
void internal_write_object(const std::string &path,
const char *data, size_t len);
private:
size_t size;
std::string segment_name;
- std::ostringstream checksums;
- TAR *t;
+
+ /* Filter support. */
+ int real_fd, filter_fd;
+ pid_t filter_pid;
+
+ // Write data to the tar file
+ void tar_write(const char *data, size_t size);
};
class TarSegmentStore {
// (segment/object) to refer to it. The optional parameter group can be
// used to control object placement; objects with different group
// parameters are kept in separate segments.
- std::string write_object(const char *data, size_t len,
- const std::string &group = "",
- const std::list<std::string> &refs = norefs);
+ ObjectReference write_object(const char *data, size_t len,
+ const std::string &group = "");
// Ensure all segments have been fully written.
void sync();
+ // Dump statistics to stdout about how much data has been written
+ void dump_stats();
+
private:
struct segment_info {
Tarfile *file;
std::string name; // UUID
- std::set<std::string> refs; // Other segments this one refers to
int count; // Objects written to this segment
};
std::string path;
std::map<std::string, struct segment_info *> segments;
- // An empty list which can be used as an argument to write_object to
- // indicate that this object depends on no others.
- static std::list<std::string> norefs;
-
// Ensure that all segments in the given group have been fully written.
void close_segment(const std::string &group);
// incrementally. Data can be an arbitrary block of binary data of any
// size. The pointer to the data need only remain valid until write() is
// called.
- //const char *get_data() const { return data; }
- //size_t get_data_len() const { return data_len; }
void set_data(const char *d, size_t len) { data = d; data_len = len; }
// Write an object to a segment, thus making it permanent. This function
// can be called at most once.
void write(TarSegmentStore *store);
+ // Compute the checksum of an object, and include it in the object
+ // reference. This should be called after write(), and the data specified
+ // by set_data() must remain valid through the call to checksum().
+ void checksum();
+
// An object is assigned a permanent name once it has been written to a
// segment. Until that time, its name cannot be determined.
- std::string get_name() const { return name; }
-
- // Logically, one object may reference other objects (such as a metadata
- // listing referncing actual file data blocks). Such references should be
- // noted explicitly. It may eventually be used to build up a tree of
- // checksums for later verifying integrity.
- void add_reference(const LbsObject *o);
+ std::string get_name() const { return ref.to_string(); }
+ ObjectReference get_ref() { return ref; }
private:
std::string group;
size_t data_len;
bool written;
- std::string name;
-
- std::set<std::string> refs;
+ ObjectReference ref;
};
+/* Program through which segment data is piped before being written to file. */
+extern const char *filter_program;
+
+/* Extension which should be appended to segments written out (.tar is already
+ * included; this adds to it) */
+extern const char *filter_extension;
+
#endif // _LBS_STORE_H
projects / cumulus.git / blobdiff