-/* LBS: An LFS-inspired filesystem backup system
- * Copyright (C) 2006 Michael Vrable
+/* Cumulus: Efficient Filesystem Backup to the Cloud
+ * Copyright (C) 2006-2008 The Cumulus Developers
+ * See the AUTHORS file for a list of contributors.
*
- * Backup data is stored in a collection of objects, which are grouped together
- * into segments for storage purposes. This file provides interfaces for
- * reading and writing objects and segments. */
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+/* Backup data is stored in a collection of objects, which are grouped together
+ * into segments for storage purposes. This implementation of the object store
+ * represents segments as TAR files and objects as files within them. */
#ifndef _LBS_STORE_H
#define _LBS_STORE_H
#include <stdint.h>
-#include <exception>
+#include <list>
#include <map>
+#include <memory>
+#include <set>
#include <string>
+#include <iostream>
#include <sstream>
-#include <vector>
+
+#include "localdb.h"
+#include "remote.h"
+#include "ref.h"
+#include "third_party/sha1.h"
+
+class LbsObject;
/* In memory datatype to represent key/value pairs of information, such as file
* metadata. Currently implemented as map<string, string>. */
typedef std::map<std::string, std::string> dictionary;
-/* IOException will be thrown if an error occurs while reading or writing in
- * one of the I/O wrappers. Depending upon the context; this may be fatal or
- * not--typically, errors reading/writing the store will be serious, but errors
- * reading an individual file are less so. */
-class IOException : public std::exception {
-private:
- std::string error;
-public:
- explicit IOException(const std::string &err) { error = err; }
- virtual ~IOException() throw () { }
- 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];
};
-/* OutputStream is an abstract interface for writing data without seeking.
- * Output could be to a file, to an object within a segment, or even to a
- * memory buffer to help serialize data. */
-class OutputStream {
+class FileFilter {
public:
- OutputStream();
- virtual ~OutputStream() { }
-
- // Write the given data buffer
- void write(const void *data, size_t len);
-
- // Return the total number of bytes written so far
- int64_t get_pos() const { return bytes_written; }
+ // It is valid for program to be NULL or empty; if so, no filtering is
+ // done.
+ static FileFilter *New(int fd, const char *program);
- // Convenience functions for writing other data types. Values are always
- // written out in little-endian order.
- void write_u8(uint8_t val);
- void write_u16(uint16_t val);
- void write_u32(uint32_t val);
- void write_u64(uint64_t val);
+ // Wait for the filter process to terminate.
+ int wait();
- void write_s32(int32_t val) { write_u32((uint32_t)val); }
- void write_s64(int64_t val) { write_u64((uint64_t)val); }
-
- void write_varint(uint64_t val);
-
- void write_string(const std::string &s);
- void write_dictionary(const dictionary &d);
-
-protected:
- // Function which actually causes a write: must be overridden by
- // implementation.
- virtual void write_internal(const void *data, size_t len) = 0;
+ // Accessors for the file descriptors.
+ int get_raw_fd() const { return fd_raw; }
+ int get_wrapped_fd() const { return fd_wrapped; }
private:
- int64_t bytes_written;
+ FileFilter(int raw, int wrapped, pid_t pid);
+
+ // Launch a process to filter data written to a file descriptor. fd_out is
+ // the file descriptor where the filtered data should be written. program
+ // is the filter program to execute (a single string which will be
+ // interpreted by /bin/sh). The return value is a file descriptor to which
+ // the data to be filtered should be written. The process ID of the filter
+ // process is stored at address filter_pid if non-NULL.
+ static int spawn_filter(int fd_out, const char *program, pid_t *filter_pid);
+
+ // The original file descriptor passed when creating the FileFilter object.
+ int fd_raw;
+
+ // The wrapped file descriptor: writes here are piped through the filter
+ // program.
+ int fd_wrapped;
+
+ // The filter process if one was launched, or -1 if there is no filter
+ // program.
+ pid_t pid;
};
-/* An OutputStream implementation which writes data to memory and returns the
- * result as a string. */
-class StringOutputStream : public OutputStream {
+/* 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. */
+class Tarfile {
public:
- StringOutputStream();
- std::string contents() const { return buf.str(); }
+ Tarfile(RemoteFile *file, const std::string &segment);
+ ~Tarfile();
-protected:
- virtual void write_internal(const void *data, size_t len);
+ void write_object(int id, const char *data, size_t len);
-private:
- std::stringstream buf;
-};
+ // Return an estimate of the size of the file.
+ size_t size_estimate();
-/* An OutputStream implementation which writes data via the C stdio layer. */
-class FileOutputStream : public OutputStream {
-public:
- explicit FileOutputStream(FILE *file);
- virtual ~FileOutputStream();
+private:
+ size_t size;
+ std::string segment_name;
-protected:
- virtual void write_internal(const void *data, size_t len);
+ RemoteFile *file;
+ std::unique_ptr<FileFilter> filter;
-private:
- FILE *f;
+ // Write data to the tar file
+ void tar_write(const char *data, size_t size);
};
-/* An OutputStream which is simply sends writes to another OutputStream, but
- * does provide separate tracking of bytes written. */
-class WrapperOutputStream : public OutputStream {
+class TarSegmentStore {
public:
- explicit WrapperOutputStream(OutputStream &o);
- virtual ~WrapperOutputStream() { }
-
-protected:
- virtual void write_internal(const void *data, size_t len);
+ // New segments will be stored in the given directory.
+ TarSegmentStore(RemoteStore *remote,
+ LocalDb *db = NULL)
+ { this->remote = remote; this->db = db; }
+ ~TarSegmentStore() { sync(); }
+
+ // Writes an object to segment in the store, and returns the name
+ // (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.
+ ObjectReference write_object(const char *data, size_t len,
+ const std::string &group = "",
+ const std::string &checksum = "",
+ double age = 0.0);
+
+ // Ensure all segments have been fully written.
+ void sync();
+
+ // Dump statistics to stdout about how much data has been written
+ void dump_stats();
private:
- OutputStream ℜ
-};
-
-/* Simple wrappers that encode integers using a StringOutputStream and return
- * the encoded result. */
-std::string encode_u16(uint16_t val);
-std::string encode_u32(uint32_t val);
-std::string encode_u64(uint64_t val);
-
-struct uuid {
- uint8_t bytes[16];
+ struct segment_info {
+ Tarfile *file;
+ std::string group;
+ std::string name; // UUID
+ int count; // Objects written to this segment
+ int data_size; // Combined size of objects written
+ std::string basename; // Name of segment without directory
+ RemoteFile *rf;
+ };
+
+ RemoteStore *remote;
+ std::map<std::string, struct segment_info *> segments;
+ LocalDb *db;
+
+ // Ensure that all segments in the given group have been fully written.
+ void close_segment(const std::string &group);
+
+ // Parse an object reference string and return just the segment name
+ // portion.
+ std::string object_reference_to_segment(const std::string &object);
};
-/* A class which is used to pack multiple objects into a single segment, with a
- * lookup table to quickly locate each object. Call new_object() to get an
- * OutputStream to which a new object may be written, and optionally
- * finish_object() when finished writing the current object. Only one object
- * may be written to a segment at a time; if multiple objects must be written
- * concurrently, they must be to different segments. */
-class SegmentWriter {
+/* An in-memory representation of an object, which can be incrementally built
+ * before it is written out to a segment. */
+class LbsObject {
public:
- SegmentWriter(OutputStream *output, struct uuid u);
- ~SegmentWriter();
-
- struct uuid get_uuid() const { return id; }
-
- // Start writing out a new object to this segment.
- OutputStream *new_object();
- void finish_object();
-
- // Utility functions for generating and formatting UUIDs for display.
- static struct uuid generate_uuid();
- static std::string format_uuid(const struct uuid u);
+ LbsObject();
+ ~LbsObject();
+
+ // If an object is placed in a group, it will be written out to segments
+ // only containing other objects in the same group. A group name is simply
+ // a string.
+ //std::string get_group() const { return group; }
+ void set_group(const std::string &g) { group = g; }
+
+ // Data in an object must be written all at once, and cannot be generated
+ // 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. If checksum is non-NULL then it is assumed to contain a hash
+ // value for the data; this provides an optimization in case the caller has
+ // already checksummed the data. Otherwise the set_data will compute a
+ // hash of the data itself.
+ void set_data(const char *d, size_t len, const char *checksum);
+
+ // Explicitly sets the age of the data, for later garbage-collection or
+ // repacking purposes. If not set, the age defaults to the current time.
+ // The age is stored in the database as a floating point value, expressing
+ // the time in Julian days.
+ void set_age(double age) { this->age = age; }
+
+ // Write an object to a segment, thus making it permanent. This function
+ // can be called at most once.
+ void write(TarSegmentStore *store);
+
+ // An object is assigned a permanent name once it has been written to a
+ // segment. Until that time, its name cannot be determined.
+ ObjectReference get_ref() { return ref; }
private:
- typedef std::vector<std::pair<int64_t, int64_t> > object_table;
-
- OutputStream *out;
- struct uuid id;
-
- int64_t object_start_offset;
- OutputStream *object_stream;
-
- object_table objects;
+ std::string group;
+ double age;
+ const char *data;
+ size_t data_len;
+ std::string checksum;
+
+ bool written;
+ ObjectReference ref;
};
-/* A SegmentStore, as the name suggests, is used to store the contents of many
- * segments. The SegmentStore internally tracks where data should be placed
- * (such as a local directory or remote storage), and allows new segments to be
- * easily created as needed. */
-class SegmentStore {
-public:
- // New segments will be stored in the given directory.
- SegmentStore(const std::string &path);
-
- SegmentWriter *new_segment();
+/* Program through which segment data is piped before being written to file. */
+extern const char *filter_program;
-private:
- std::string directory;
-};
+/* 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