-/* LBS: An LFS-inspired filesystem backup system
- * Copyright (C) 2006 Michael Vrable
+/* Cumulus: Efficient Filesystem Backup to the Cloud
+ * Copyright (C) 2008-2009 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.
+ */
-#include <assert.h>
-#include <uuid/uuid.h>
+/* 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. */
+#include <assert.h>
+#include <errno.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <sys/resource.h>
+#include <sys/wait.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <time.h>
+
+#include <algorithm>
+#include <list>
+#include <map>
+#include <set>
+#include <string>
+#include <iostream>
+
+#include "hash.h"
+#include "localdb.h"
#include "store.h"
-
+#include "ref.h"
+#include "util.h"
+
+using std::max;
+using std::list;
+using std::map;
+using std::pair;
+using std::set;
using std::string;
-OutputStream::OutputStream()
- : bytes_written(0)
-{
-}
+/* Default filter program is bzip2 */
+const char *filter_program = "bzip2 -c";
+const char *filter_extension = ".bz2";
-void OutputStream::write(const void *data, size_t len)
+Tarfile::Tarfile(RemoteFile *file, const string &segment)
+ : size(0),
+ segment_name(segment)
{
- write_internal(data, len);
- bytes_written += len;
-}
+ assert(sizeof(struct tar_header) == TAR_BLOCK_SIZE);
-void OutputStream::write_u8(uint8_t val)
-{
- write(&val, 1);
+ this->file = file;
+ this->filter.reset(FileFilter::New(file->get_fd(), filter_program));
}
-void OutputStream::write_u16(uint16_t val)
+Tarfile::~Tarfile()
{
- unsigned char buf[2];
+ char buf[TAR_BLOCK_SIZE];
- buf[0] = val & 0xff;
- buf[1] = (val >> 8) & 0xff;
- write(buf, 2);
-}
+ /* Append the EOF marker: two blocks filled with nulls. */
+ memset(buf, 0, sizeof(buf));
+ tar_write(buf, TAR_BLOCK_SIZE);
+ tar_write(buf, TAR_BLOCK_SIZE);
-void OutputStream::write_u32(uint32_t val)
-{
- unsigned char buf[4];
+ if (close(filter->get_wrapped_fd()) != 0)
+ fatal("Error closing Tarfile");
- buf[0] = val & 0xff;
- buf[1] = (val >> 8) & 0xff;
- buf[2] = (val >> 16) & 0xff;
- buf[3] = (val >> 24) & 0xff;
- write(buf, 4);
+ /* ...and wait for filter process to finish. */
+ if (filter->wait() != 0) {
+ fatal("Filter process error");
+ }
}
-void OutputStream::write_u64(uint64_t val)
-{
- unsigned char buf[8];
-
- buf[0] = val & 0xff;
- buf[1] = (val >> 8) & 0xff;
- buf[2] = (val >> 16) & 0xff;
- buf[3] = (val >> 24) & 0xff;
- buf[4] = (val >> 32) & 0xff;
- buf[5] = (val >> 40) & 0xff;
- buf[6] = (val >> 48) & 0xff;
- buf[7] = (val >> 56) & 0xff;
- write(buf, 8);
-}
+FileFilter::FileFilter(int raw, int wrapped, pid_t pid)
+ : fd_raw(raw), fd_wrapped(wrapped), pid(pid) { }
-/* Writes an integer to an output stream using a variable-sized representation:
- * seven bits are written at a time (little-endian), and the eigth bit of each
- * byte is set if more data follows. */
-void OutputStream::write_varint(uint64_t val)
+FileFilter *FileFilter::New(int fd, const char *program)
{
- do {
- uint8_t remainder = (val & 0x7f);
- val >>= 7;
- if (val)
- remainder |= 0x80;
- write_u8(remainder);
- } while (val);
-}
+ if (program == NULL || strlen(program) == 0) {
+ return new FileFilter(fd, fd, -1);
+ }
-/* Write an arbitrary string by first writing out the length, followed by the
- * data itself. */
-void OutputStream::write_string(const string &s)
-{
- size_t len = s.length();
- write_varint(len);
- write(s.data(), len);
+ pid_t pid;
+ int wrapped_fd = spawn_filter(fd, program, &pid);
+ return new FileFilter(fd, wrapped_fd, pid);
}
-void OutputStream::write_dictionary(const dictionary &d)
+int FileFilter::wait()
{
- size_t size = d.size();
- size_t written = 0;
-
- write_varint(size);
+ // No filter program was launched implies no need to wait.
+ if (pid == -1)
+ return 0;
+
+ // The raw file descriptor was held open to track the output file size, but
+ // is not needed any longer.
+ close(fd_raw);
+
+ int status;
+ if (waitpid(pid, &status, 0) < 0) {
+ fprintf(stderr, "Error waiting for filter process: %m\n");
+ return -1;
+ }
- for (dictionary::const_iterator i = d.begin(); i != d.end(); ++i) {
- write_string(i->first);
- write_string(i->second);
- written++;
+ if (!WIFEXITED(status) || WEXITSTATUS(status) != 0) {
+ fprintf(stderr, "Filter process error: %d\n", WEXITSTATUS(status));
}
- assert(written == size);
+ return status;
}
-StringOutputStream::StringOutputStream()
- : buf(std::ios_base::out)
+/* Launch a child process which can act as a filter (compress, encrypt, etc.)
+ * on the TAR output. The file descriptor to which output should be written
+ * must be specified; the return value is the file descriptor which will be
+ * attached to the standard input of the filter program. */
+int FileFilter::spawn_filter(int fd_out, const char *program, pid_t *filter_pid)
{
-}
+ int fds[2];
+ pid_t pid;
-void StringOutputStream::write_internal(const void *data, size_t len)
-{
- buf.write((const char *)data, len);
- if (!buf.good())
- throw IOException("error writing to StringOutputStream");
-}
+ /* Create a pipe for communicating with the filter process. */
+ if (pipe(fds) < 0) {
+ fatal("Unable to create pipe for filter");
+ }
-FileOutputStream::FileOutputStream(FILE *file)
-{
- f = file;
-}
+ /* Create a child process which can exec() the filter program. */
+ pid = fork();
+ if (pid < 0)
+ fatal("Unable to fork filter process");
+
+ if (pid > 0) {
+ /* Parent process */
+ close(fds[0]);
+ cloexec(fds[1]);
+ if (filter_pid != NULL)
+ *filter_pid = pid;
+ } else {
+ /* Child process. Rearrange file descriptors. stdin is fds[0], stdout
+ * is fd_out, stderr is unchanged. */
+ close(fds[1]);
+
+ if (dup2(fds[0], 0) < 0)
+ exit(1);
+ close(fds[0]);
+
+ if (dup2(fd_out, 1) < 0)
+ exit(1);
+ close(fd_out);
+
+ /* Exec the filter program. */
+ execlp("/bin/sh", "/bin/sh", "-c", program, NULL);
+
+ /* Should not reach here except for error cases. */
+ fprintf(stderr, "Could not exec filter: %m\n");
+ exit(1);
+ }
-FileOutputStream::~FileOutputStream()
-{
- fclose(f);
+ return fds[1];
}
-void FileOutputStream::write_internal(const void *data, size_t len)
+void Tarfile::tar_write(const char *data, size_t len)
{
- size_t res;
+ size += len;
- res = fwrite(data, 1, len, f);
- if (res != len) {
- throw IOException("write error");
+ while (len > 0) {
+ int res = write(filter->get_wrapped_fd(), data, len);
+
+ if (res < 0) {
+ if (errno == EINTR)
+ continue;
+ fprintf(stderr, "Write error: %m\n");
+ fatal("Write error");
+ }
+
+ len -= res;
+ data += res;
}
}
-WrapperOutputStream::WrapperOutputStream(OutputStream &o)
- : real(o)
+void Tarfile::write_object(int id, const char *data, size_t len)
{
-}
+ struct tar_header header;
+ memset(&header, 0, sizeof(header));
+
+ char buf[64];
+ sprintf(buf, "%08x", id);
+ string path = segment_name + "/" + buf;
+
+ assert(path.size() < 100);
+ memcpy(header.name, path.data(), path.size());
+ sprintf(header.mode, "%07o", 0600);
+ sprintf(header.uid, "%07o", 0);
+ sprintf(header.gid, "%07o", 0);
+ sprintf(header.size, "%011o", (int)len);
+ sprintf(header.mtime, "%011o", (int)time(NULL));
+ header.typeflag = '0';
+ strcpy(header.magic, "ustar ");
+ strcpy(header.uname, "root");
+ strcpy(header.gname, "root");
+
+ memset(header.chksum, ' ', sizeof(header.chksum));
+ int checksum = 0;
+ for (int i = 0; i < TAR_BLOCK_SIZE; i++) {
+ checksum += ((uint8_t *)&header)[i];
+ }
+ sprintf(header.chksum, "%06o", checksum);
-void WrapperOutputStream::write_internal(const void *data, size_t len)
-{
- real.write(data, len);
-}
+ tar_write((const char *)&header, TAR_BLOCK_SIZE);
-/* Utility functions, for encoding data types to strings. */
-string encode_u16(uint16_t val)
-{
- StringOutputStream s;
- s.write_u16(val);
- return s.contents();
-}
+ if (len == 0)
+ return;
-string encode_u32(uint32_t val)
-{
- StringOutputStream s;
- s.write_u32(val);
- return s.contents();
-}
+ tar_write(data, len);
-string encode_u64(uint64_t val)
-{
- StringOutputStream s;
- s.write_u64(val);
- return s.contents();
+ char padbuf[TAR_BLOCK_SIZE];
+ size_t blocks = (len + TAR_BLOCK_SIZE - 1) / TAR_BLOCK_SIZE;
+ size_t padding = blocks * TAR_BLOCK_SIZE - len;
+ memset(padbuf, 0, padding);
+ tar_write(padbuf, padding);
}
-SegmentWriter::SegmentWriter(OutputStream *output, struct uuid u)
- : out(output),
- id(u),
- object_stream(NULL)
+/* Estimate the size based on the size of the actual output file on disk.
+ * However, it might be the case that the filter program is buffering all its
+ * data, and might potentially not write a single byte until we have closed
+ * our end of the pipe. If we don't do so until we see data written, we have
+ * a problem. So, arbitrarily pick an upper bound on the compression ratio
+ * that the filter will achieve (128:1), and return a size estimate which is
+ * the larger of a) bytes actually seen written to disk, and b) input
+ * bytes/128. */
+size_t Tarfile::size_estimate()
{
- /* Write out the segment header first. */
- static const char signature[] = "LBSSEG0\n";
- out->write(signature, strlen(signature));
- out->write(id.bytes, sizeof(struct uuid));
+ struct stat statbuf;
+
+ if (fstat(filter->get_raw_fd(), &statbuf) == 0)
+ return max((int64_t)statbuf.st_size, (int64_t)(size / 128));
+
+ /* Couldn't stat the file on disk, so just return the actual number of
+ * bytes, before compression. */
+ return size;
}
-SegmentWriter::~SegmentWriter()
+static const size_t SEGMENT_SIZE = 4 * 1024 * 1024;
+
+/* Backup size summary: segment type -> (uncompressed size, compressed size) */
+static map<string, pair<int64_t, int64_t> > group_sizes;
+
+ObjectReference TarSegmentStore::write_object(const char *data, size_t len,
+ const std::string &group,
+ const std::string &checksum,
+ double age)
{
- if (object_stream)
- finish_object();
-
- // Write out the object table which gives the sizes and locations of all
- // objects, and then add the trailing signature, which indicates the end of
- // the segment and gives the offset of the object table.
- int64_t index_offset = out->get_pos();
-
- for (object_table::const_iterator i = objects.begin();
- i != objects.end(); ++i) {
- out->write_s64(i->first);
- out->write_s64(i->second);
+ struct segment_info *segment;
+
+ // Find the segment into which the object should be written, looking up by
+ // group. If no segment exists yet, create one.
+ if (segments.find(group) == segments.end()) {
+ segment = new segment_info;
+
+ segment->name = generate_uuid();
+ segment->group = group;
+ segment->basename = segment->name + ".tar";
+ segment->basename += filter_extension;
+ segment->count = 0;
+ segment->data_size = 0;
+ segment->rf = remote->alloc_file(segment->basename,
+ group == "metadata" ? "segments0"
+ : "segments1");
+ segment->file = new Tarfile(segment->rf, segment->name);
+
+ segments[group] = segment;
+ } else {
+ segment = segments[group];
}
- static const char signature2[] = "LBSEND";
- out->write(signature2, strlen(signature2));
- out->write_s64(index_offset);
- out->write_u32(objects.size());
+ int id = segment->count;
+ char id_buf[64];
+ sprintf(id_buf, "%08x", id);
- /* The SegmentWriter takes ownership of the OutputStream it is writing to,
- * and destroys it automatically when done with the segment. */
- delete out;
-}
+ segment->file->write_object(id, data, len);
+ segment->count++;
+ segment->data_size += len;
-OutputStream *SegmentWriter::new_object()
-{
- if (object_stream)
- finish_object();
+ group_sizes[group].first += len;
+
+ ObjectReference ref(segment->name, id_buf);
+ ref.set_range(0, len, true);
+ if (checksum.size() > 0)
+ ref.set_checksum(checksum);
+ if (db != NULL)
+ db->StoreObject(ref, age);
- object_start_offset = out->get_pos();
- object_stream = new WrapperOutputStream(*out);
+ // If this segment meets or exceeds the size target, close it so that
+ // future objects will go into a new segment.
+ if (segment->file->size_estimate() >= SEGMENT_SIZE)
+ close_segment(group);
- return object_stream;
+ return ref;
}
-void SegmentWriter::finish_object()
+void TarSegmentStore::sync()
{
- assert(object_stream != NULL);
-
- // store (start, length) information for locating this object
- objects.push_back(std::make_pair(object_start_offset,
- object_stream->get_pos()));
+ while (!segments.empty())
+ close_segment(segments.begin()->first);
+}
- delete object_stream;
- object_stream = NULL;
+void TarSegmentStore::dump_stats()
+{
+ printf("Data written:\n");
+ for (map<string, pair<int64_t, int64_t> >::iterator i = group_sizes.begin();
+ i != group_sizes.end(); ++i) {
+ printf(" %s: %lld (%lld compressed)\n", i->first.c_str(),
+ (long long)i->second.first, (long long)i->second.second);
+ }
}
-struct uuid SegmentWriter::generate_uuid()
+void TarSegmentStore::close_segment(const string &group)
{
- struct uuid u;
+ struct segment_info *segment = segments[group];
- uuid_generate(u.bytes);
+ delete segment->file;
+
+ if (db != NULL) {
+ struct stat stat_buf;
+ int disk_size = 0;
+ if (stat(segment->rf->get_local_path().c_str(), &stat_buf) == 0) {
+ disk_size = stat_buf.st_size;
+ group_sizes[segment->group].second += disk_size;
+ }
+
+ string checksum
+ = Hash::hash_file(segment->rf->get_local_path().c_str());
+
+ db->SetSegmentMetadata(segment->name, segment->rf->get_remote_path(),
+ checksum, group, segment->data_size, disk_size);
+ }
- return u;
+ segment->rf->send();
+
+ segments.erase(segments.find(group));
+ delete segment;
}
-string SegmentWriter::format_uuid(const struct uuid u)
+string TarSegmentStore::object_reference_to_segment(const string &object)
{
- // A UUID only takes 36 bytes, plus the trailing '\0', so this is safe.
- char buf[40];
-
- uuid_unparse_lower(u.bytes, buf);
+ return object;
+}
- return string(buf);
+LbsObject::LbsObject()
+ : group(""), age(0.0), data(NULL), data_len(0), written(false)
+{
}
-SegmentStore::SegmentStore(const string &path)
- : directory(path)
+LbsObject::~LbsObject()
{
}
-SegmentWriter *SegmentStore::new_segment()
+void LbsObject::set_data(const char *d, size_t len, const char *checksum)
{
- struct uuid id = SegmentWriter::generate_uuid();
- string filename = directory + "/" + SegmentWriter::format_uuid(id);
+ data = d;
+ data_len = len;
+
+ if (checksum != NULL) {
+ this->checksum = checksum;
+ } else {
+ Hash *hash = Hash::New();
+ hash->update(data, data_len);
+ this->checksum = hash->digest_str();
+ delete hash;
+ }
+}
- FILE *f = fopen(filename.c_str(), "wb");
- if (f == NULL)
- throw IOException("Unable to open new segment");
+void LbsObject::write(TarSegmentStore *store)
+{
+ assert(data != NULL);
+ assert(!written);
- return new SegmentWriter(new FileOutputStream(f), id);
+ ref = store->write_object(data, data_len, group, checksum, age);
+ written = true;
}
projects / cumulus.git / blobdiff