diff options
Diffstat (limited to 'src/test/osd/ErasureCodeExample.h')
| -rw-r--r-- | src/test/osd/ErasureCodeExample.h | 96 |
1 files changed, 71 insertions, 25 deletions
diff --git a/src/test/osd/ErasureCodeExample.h b/src/test/osd/ErasureCodeExample.h index 896e614c6b5..0fd55187559 100644 --- a/src/test/osd/ErasureCodeExample.h +++ b/src/test/osd/ErasureCodeExample.h @@ -19,45 +19,63 @@ #include <unistd.h> #include <errno.h> +#include <algorithm> #include <sstream> #include "osd/ErasureCodeInterface.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 ErasureCodeInterface { public: - useconds_t delay; - ErasureCodeExample(const map<std::string,std::string> ¶meters) : - delay(0) - { - if (parameters.find("usleep") != parameters.end()) { - std::istringstream ss(parameters.find("usleep")->second); - ss >> delay; - usleep(delay); - } - } - virtual ~ErasureCodeExample() {} virtual int minimum_to_decode(const set<int> &want_to_read, const set<int> &available_chunks, set<int> *minimum) { - if (available_chunks.size() < DATA_CHUNKS) + 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; - set<int>::iterator i; - unsigned j; - for (i = available_chunks.begin(), j = 0; j < DATA_CHUNKS; i++, j++) - minimum->insert(*i); - return 0; + } } virtual int minimum_to_decode_with_cost(const set<int> &want_to_read, const map<int, int> &available, set<int> *minimum) { + // + // 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 = available.begin(); - i != available.end(); + 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); @@ -66,16 +84,28 @@ public: virtual int encode(const set<int> &want_to_encode, const bufferlist &in, map<int, bufferlist> *encoded) { + // + // make sure all data chunks have the same length, allocating + // padding if necessary. + // unsigned chunk_length = ( in.length() / DATA_CHUNKS ) + 1; unsigned length = chunk_length * ( DATA_CHUNKS + CODING_CHUNKS ); bufferlist out(in); bufferptr pad(length - in.length()); pad.zero(0, DATA_CHUNKS); 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 * DATA_CHUNKS; i++) - p[i + 2 * chunk_length] = - p[i + 0 * chunk_length] ^ p[i + 1 * chunk_length]; + 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.buffers().front(); for (set<int>::iterator j = want_to_encode.begin(); j != want_to_encode.end(); @@ -89,14 +119,30 @@ public: virtual int decode(const set<int> &want_to_read, const map<int, bufferlist> &chunks, map<int, bufferlist> *decoded) { - + // + // 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 (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 { + } 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. + // bufferptr chunk(chunk_length); map<int, bufferlist>::const_iterator k = chunks.begin(); const char *a = k->second.buffers().front().c_str(); |