X-Git-Url: http://git.vrable.net/?p=cumulus.git;a=blobdiff_plain;f=store.h;h=b58ea3468a0782daefab1f784c73e1c4ce2c360f;hp=c358770fae31da977ebc02bdf2650ef6c79ecd01;hb=HEAD;hpb=013636b17f3e44f5ac4837750a3888999d35d2f8 diff --git a/store.h b/store.h index c358770..b58ea34 100644 --- a/store.h +++ b/store.h @@ -1,7 +1,23 @@ -/* LBS: An LFS-inspired filesystem backup system - * Copyright (C) 2006-2008 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 * represents segments as TAR files and objects as files within them. */ @@ -12,6 +28,7 @@ #include #include +#include #include #include #include @@ -19,8 +36,8 @@ #include "localdb.h" #include "remote.h" -#include "sha1.h" #include "ref.h" +#include "third_party/sha1.h" class LbsObject; @@ -28,19 +45,6 @@ class LbsObject; * 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; @@ -65,6 +69,42 @@ struct tar_header char padding[12]; }; +class FileFilter { +public: + // 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 * may only be written out all at once, since the tar header must be written * first; incremental writing is not supported. */ @@ -83,10 +123,7 @@ private: std::string segment_name; RemoteFile *file; - - /* Filter support. */ - int real_fd, filter_fd; - pid_t filter_pid; + std::unique_ptr filter; // Write data to the tar file void tar_write(const char *data, size_t size); @@ -105,7 +142,9 @@ public: // 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 &group = "", + const std::string &checksum = "", + double age = 0.0); // Ensure all segments have been fully written. void sync(); @@ -116,9 +155,10 @@ public: private: struct segment_info { Tarfile *file; + std::string group; std::string name; // UUID int count; // Objects written to this segment - int size; // Combined size of objects written + int data_size; // Combined size of objects written std::string basename; // Name of segment without directory RemoteFile *rf; }; @@ -151,27 +191,32 @@ public: // 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. - void set_data(const char *d, size_t len) { data = d; data_len = len; } + // 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); - // 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 ref.to_string(); } 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; @@ -184,12 +229,4 @@ extern const char *filter_program; * included; this adds to it) */ extern const char *filter_extension; -/* 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. */ -int spawn_filter(int fd_out, const char *program, pid_t *filter_pid); - #endif // _LBS_STORE_H