+++ /dev/null
-// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
-// vim: ts=8 sw=2 smarttab
-/*
- * Ceph distributed storage system
- *
- * Copyright (C) 2013 Cloudwatt <libre.licensing@cloudwatt.com>
- *
- * Author: Loic Dachary <loic@dachary.org>
- *
- * This library is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Lesser General Public
- * License as published by the Free Software Foundation; either
- * version 2.1 of the License, or (at your option) any later version.
- *
- */
-
-#ifndef CEPH_ERASURE_CODE_EXAMPLE_H
-#define CEPH_ERASURE_CODE_EXAMPLE_H
-
-#include <unistd.h>
-#include <errno.h>
-#include <algorithm>
-#include <sstream>
-
-#include "crush/CrushWrapper.h"
-#include "osd/osd_types.h"
-#include "erasure-code/ErasureCode.h"
-
-#define FIRST_DATA_CHUNK 0
-#define SECOND_DATA_CHUNK 1
-#define DATA_CHUNKS 2u
-
-#define CODING_CHUNK 2
-#define CODING_CHUNKS 1u
-
-#define MINIMUM_TO_RECOVER 2u
-
-class ErasureCodeExample : public ErasureCode {
-public:
- ~ErasureCodeExample() override {}
-
- int create_rule(const string &name,
- CrushWrapper &crush,
- ostream *ss) const override {
- return crush.add_simple_rule(name, "default", "host", "",
- "indep", pg_pool_t::TYPE_ERASURE, ss);
- }
-
- int minimum_to_decode(const set<int> &want_to_read,
- const set<int> &available_chunks,
- set<int> *minimum) override {
- if (includes(available_chunks.begin(), available_chunks.end(),
- want_to_read.begin(), want_to_read.end())) {
- *minimum = want_to_read;
- return 0;
- } else if (available_chunks.size() >= MINIMUM_TO_RECOVER) {
- *minimum = available_chunks;
- return 0;
- } else {
- return -EIO;
- }
- }
-
- int minimum_to_decode_with_cost(const set<int> &want_to_read,
- const map<int, int> &available,
- set<int> *minimum) override {
- //
- // If one chunk is more expensive to fetch than the others,
- // recover it instead. For instance, if the cost reflects the
- // time it takes for a chunk to be retrieved from a remote
- // OSD and if CPU is cheap, it could make sense to recover
- // instead of fetching the chunk.
- //
- map<int, int> c2c(available);
- if (c2c.size() > DATA_CHUNKS) {
- if (c2c[FIRST_DATA_CHUNK] > c2c[SECOND_DATA_CHUNK] &&
- c2c[FIRST_DATA_CHUNK] > c2c[CODING_CHUNK])
- c2c.erase(FIRST_DATA_CHUNK);
- else if(c2c[SECOND_DATA_CHUNK] > c2c[FIRST_DATA_CHUNK] &&
- c2c[SECOND_DATA_CHUNK] > c2c[CODING_CHUNK])
- c2c.erase(SECOND_DATA_CHUNK);
- else if(c2c[CODING_CHUNK] > c2c[FIRST_DATA_CHUNK] &&
- c2c[CODING_CHUNK] > c2c[SECOND_DATA_CHUNK])
- c2c.erase(CODING_CHUNK);
- }
- set <int> available_chunks;
- for (map<int, int>::const_iterator i = c2c.begin();
- i != c2c.end();
- ++i)
- available_chunks.insert(i->first);
- return minimum_to_decode(want_to_read, available_chunks, minimum);
- }
-
- unsigned int get_chunk_count() const override {
- return DATA_CHUNKS + CODING_CHUNKS;
- }
-
- unsigned int get_data_chunk_count() const override {
- return DATA_CHUNKS;
- }
-
- unsigned int get_chunk_size(unsigned int object_size) const override {
- return ( object_size / DATA_CHUNKS ) + 1;
- }
-
- int encode(const set<int> &want_to_encode,
- const bufferlist &in,
- map<int, bufferlist> *encoded) override {
- //
- // make sure all data chunks have the same length, allocating
- // padding if necessary.
- //
- unsigned int chunk_length = get_chunk_size(in.length());
- bufferlist out(in);
- unsigned int width = get_chunk_count() * get_chunk_size(in.length());
- bufferptr pad(width - in.length());
- pad.zero(0, get_data_chunk_count());
- out.push_back(pad);
- //
- // compute the coding chunk with first chunk ^ second chunk
- //
- char *p = out.c_str();
- for (unsigned i = 0; i < chunk_length; i++)
- p[i + CODING_CHUNK * chunk_length] =
- p[i + FIRST_DATA_CHUNK * chunk_length] ^
- p[i + SECOND_DATA_CHUNK * chunk_length];
- //
- // populate the bufferlist with bufferptr pointing
- // to chunk boundaries
- //
- const bufferptr &ptr = out.front();
- for (set<int>::iterator j = want_to_encode.begin();
- j != want_to_encode.end();
- ++j) {
- bufferptr chunk(ptr, (*j) * chunk_length, chunk_length);
- (*encoded)[*j].push_front(chunk);
- }
- return 0;
- }
-
- int encode_chunks(const set<int> &want_to_encode,
- map<int, bufferlist> *encoded) override {
- ceph_abort();
- return 0;
- }
-
- int decode(const set<int> &want_to_read,
- const map<int, bufferlist> &chunks,
- map<int, bufferlist> *decoded) override {
- //
- // All chunks have the same size
- //
- unsigned chunk_length = (*chunks.begin()).second.length();
- for (set<int>::iterator i = want_to_read.begin();
- i != want_to_read.end();
- ++i) {
- if (chunks.find(*i) != chunks.end()) {
- //
- // If the chunk is available, just copy the bufferptr pointer
- // to the decoded argument.
- //
- (*decoded)[*i] = chunks.find(*i)->second;
- } else if(chunks.size() != 2) {
- //
- // If a chunk is missing and there are not enough chunks
- // to recover, abort.
- //
- return -ERANGE;
- } else {
- //
- // No matter what the missing chunk is, XOR of the other
- // two recovers it.
- //
- map<int, bufferlist>::const_iterator k = chunks.begin();
- const char *a = k->second.front().c_str();
- ++k;
- const char *b = k->second.front().c_str();
- bufferptr chunk(chunk_length);
- char *c = chunk.c_str();
- for (unsigned j = 0; j < chunk_length; j++) {
- c[j] = a[j] ^ b[j];
- }
- (*decoded)[*i].push_front(chunk);
- }
- }
- return 0;
- }
-
- int decode_chunks(const set<int> &want_to_read,
- const map<int, bufferlist> &chunks,
- map<int, bufferlist> *decoded) override {
- ceph_abort();
- return 0;
- }
-
- const vector<int> &get_chunk_mapping() const override {
- static vector<int> mapping;
- return mapping;
- }
-
-};
-
-#endif
Code Review / stor4nfv.git / blobdiff