X-Git-Url: http://git.vrable.net/?p=cumulus.git;a=blobdiff_plain;f=store.h;h=b58ea3468a0782daefab1f784c73e1c4ce2c360f;hp=6acee7fb4b0fce8707eb3aa02a095a0cfabe9ead;hb=HEAD;hpb=d5afe2c08724b4b263a76f187e39861c1e6e0cf5 diff --git a/store.h b/store.h index 6acee7f..b58ea34 100644 --- a/store.h +++ b/store.h @@ -1,41 +1,108 @@ -/* 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 + * 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 - * 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_TARSTORE_H -#define _LBS_TARSTORE_H +#ifndef _LBS_STORE_H +#define _LBS_STORE_H #include -#include #include #include +#include #include #include #include #include -#include "sha1.h" +#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. */ typedef std::map 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; +/* 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]; +}; + +class FileFilter { public: - explicit IOException(const std::string &err) { error = err; } - virtual ~IOException() throw () { } - std::string getError() const { return error; } + // It is valid for program to be NULL or empty; if so, no filtering is + // done. + static FileFilter *New(int fd, const char *program); + + // Wait for the filter process to terminate. + int wait(); + + // Accessors for the file descriptors. + int get_raw_fd() const { return fd_raw; } + int get_wrapped_fd() const { return fd_wrapped; } + +private: + 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; }; /* A simple wrapper around a single TAR file to represent a segment. Objects @@ -43,55 +110,62 @@ public: * first; incremental writing is not supported. */ class Tarfile { public: - Tarfile(const std::string &path, const std::string &segment); + Tarfile(RemoteFile *file, const std::string &segment); ~Tarfile(); 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; } - - void internal_write_object(const std::string &path, - const char *data, size_t len); + size_t size_estimate(); private: size_t size; std::string segment_name; - std::ostringstream checksums; - TAR *t; + + RemoteFile *file; + std::unique_ptr filter; + + // Write data to the tar file + void tar_write(const char *data, size_t size); }; class TarSegmentStore { public: // New segments will be stored in the given directory. - TarSegmentStore(const std::string &path) { this->path = path; } + 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. - std::string write_object(const char *data, size_t len, - const std::string &group = "", - const std::list &refs = norefs); + 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: struct segment_info { Tarfile *file; + std::string group; std::string name; // UUID - std::set refs; // Other segments this one refers to 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; }; - std::string path; + RemoteStore *remote; std::map 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 norefs; + LocalDb *db; // Ensure that all segments in the given group have been fully written. void close_segment(const std::string &group); @@ -101,4 +175,58 @@ private: std::string object_reference_to_segment(const std::string &object); }; -#endif // _LBS_TARSTORE_H +/* An in-memory representation of an object, which can be incrementally built + * before it is written out to a segment. */ +class LbsObject { +public: + 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: + std::string group; + double age; + const char *data; + size_t data_len; + std::string checksum; + + bool written; + 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