X-Git-Url: http://git.vrable.net/?p=cumulus.git;a=blobdiff_plain;f=store.h;h=b58ea3468a0782daefab1f784c73e1c4ce2c360f;hp=8344dda39fce062fe42088f30b80ea529c3ab839;hb=HEAD;hpb=08721c894385b530ed501498a02d824b8eba7228 diff --git a/store.h b/store.h index 8344dda..b58ea34 100644 --- a/store.h +++ b/store.h @@ -1,152 +1,232 @@ -/* 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 -#include +#include #include +#include +#include #include +#include #include -#include + +#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; -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() { } + // It is valid for program to be NULL or empty; if so, no filtering is + // done. + static FileFilter *New(int fd, const char *program); - // Write the given data buffer - void write(const void *data, size_t len); + // Wait for the filter process to terminate. + int wait(); - // Return the total number of bytes written so far - int64_t get_pos() const { return bytes_written; } - - // 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); - - 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 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 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); }; -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 > object_table; - - OutputStream &out; - struct uuid id; + std::string group; + double age; + const char *data; + size_t data_len; + std::string checksum; + + bool written; + ObjectReference ref; +}; - int64_t object_start_offset; - OutputStream *object_stream; +/* Program through which segment data is piped before being written to file. */ +extern const char *filter_program; - object_table objects; -}; +/* 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