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+// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
+// vim: ts=8 sw=2 smarttab
+/*
+ * Ceph - scalable distributed file system
+ *
+ * Copyright (C) 2013 Inktank Storage, Inc.
+ *
+ * This is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License version 2.1, as published by the Free Software
+ * Foundation. See file COPYING.
+ *
+ */
+
+#ifndef SNAPMAPPER_H
+#define SNAPMAPPER_H
+
+#include <string>
+#include <set>
+#include <utility>
+#include <string.h>
+
+#include "common/map_cacher.hpp"
+#include "common/hobject.h"
+#include "include/buffer.h"
+#include "include/encoding.h"
+#include "include/object.h"
+#include "os/ObjectStore.h"
+
+class OSDriver : public MapCacher::StoreDriver<std::string, bufferlist> {
+ ObjectStore *os;
+ ObjectStore::CollectionHandle ch;
+ ghobject_t hoid;
+
+public:
+ class OSTransaction : public MapCacher::Transaction<std::string, bufferlist> {
+ friend class OSDriver;
+ coll_t cid;
+ ghobject_t hoid;
+ ObjectStore::Transaction *t;
+ OSTransaction(
+ const coll_t &cid,
+ const ghobject_t &hoid,
+ ObjectStore::Transaction *t)
+ : cid(cid), hoid(hoid), t(t) {}
+ public:
+ void set_keys(
+ const std::map<std::string, bufferlist> &to_set) override {
+ t->omap_setkeys(cid, hoid, to_set);
+ }
+ void remove_keys(
+ const std::set<std::string> &to_remove) override {
+ t->omap_rmkeys(cid, hoid, to_remove);
+ }
+ void add_callback(
+ Context *c) override {
+ t->register_on_applied(c);
+ }
+ };
+
+ OSTransaction get_transaction(
+ ObjectStore::Transaction *t) {
+ return OSTransaction(ch->cid, hoid, t);
+ }
+
+ OSDriver(ObjectStore *os, const coll_t& cid, const ghobject_t &hoid) :
+ os(os),
+ hoid(hoid) {
+ ch = os->open_collection(cid);
+ }
+ int get_keys(
+ const std::set<std::string> &keys,
+ std::map<std::string, bufferlist> *out) override;
+ int get_next(
+ const std::string &key,
+ pair<std::string, bufferlist> *next) override;
+};
+
+/**
+ * SnapMapper
+ *
+ * Manages two mappings:
+ * 1) hobject_t -> {snapid}
+ * 2) snapid -> {hobject_t}
+ *
+ * We accomplish this using two sets of keys:
+ * 1) OBJECT_PREFIX + obj.str() -> encoding of object_snaps
+ * 2) MAPPING_PREFIX + snapid_t + obj.str() -> encoding of pair<snapid_t, obj>
+ *
+ * The on disk strings and encodings are implemented in to_raw, to_raw_key,
+ * from_raw, to_object_key.
+ *
+ * The object -> {snapid} mapping is primarily included so that the
+ * SnapMapper state can be verified against the external PG state during
+ * scrub etc.
+ *
+ * The 2) mapping is arranged such that all objects in a particular
+ * snap will sort together, and so that all objects in a pg for a
+ * particular snap will group under up to 8 prefixes.
+ */
+class SnapMapper {
+public:
+ CephContext* cct;
+ struct object_snaps {
+ hobject_t oid;
+ std::set<snapid_t> snaps;
+ object_snaps(hobject_t oid, const std::set<snapid_t> &snaps)
+ : oid(oid), snaps(snaps) {}
+ object_snaps() {}
+ void encode(bufferlist &bl) const;
+ void decode(bufferlist::const_iterator &bp);
+ };
+
+private:
+ MapCacher::MapCacher<std::string, bufferlist> backend;
+
+ static const std::string MAPPING_PREFIX;
+ static const std::string OBJECT_PREFIX;
+
+ static std::string get_prefix(snapid_t snap);
+
+ std::string to_raw_key(
+ const std::pair<snapid_t, hobject_t> &to_map);
+
+ std::pair<std::string, bufferlist> to_raw(
+ const std::pair<snapid_t, hobject_t> &to_map);
+
+ static bool is_mapping(const std::string &to_test);
+
+ std::pair<snapid_t, hobject_t> from_raw(
+ const std::pair<std::string, bufferlist> &image);
+
+ std::string to_object_key(const hobject_t &hoid);
+
+ int get_snaps(const hobject_t &oid, object_snaps *out);
+
+ void set_snaps(
+ const hobject_t &oid,
+ const object_snaps &out,
+ MapCacher::Transaction<std::string, bufferlist> *t);
+
+ void clear_snaps(
+ const hobject_t &oid,
+ MapCacher::Transaction<std::string, bufferlist> *t);
+
+ // True if hoid belongs in this mapping based on mask_bits and match
+ bool check(const hobject_t &hoid) const;
+
+ int _remove_oid(
+ const hobject_t &oid, ///< [in] oid to remove
+ MapCacher::Transaction<std::string, bufferlist> *t ///< [out] transaction
+ );
+
+public:
+ static string make_shard_prefix(shard_id_t shard) {
+ if (shard == shard_id_t::NO_SHARD)
+ return string();
+ char buf[20];
+ int r = snprintf(buf, sizeof(buf), ".%x", (int)shard);
+ ceph_assert(r < (int)sizeof(buf));
+ return string(buf, r) + '_';
+ }
+ uint32_t mask_bits;
+ const uint32_t match;
+ string last_key_checked;
+ const int64_t pool;
+ const shard_id_t shard;
+ const string shard_prefix;
+ SnapMapper(
+ CephContext* cct,
+ MapCacher::StoreDriver<std::string, bufferlist> *driver,
+ uint32_t match, ///< [in] pgid
+ uint32_t bits, ///< [in] current split bits
+ int64_t pool, ///< [in] pool
+ shard_id_t shard ///< [in] shard
+ )
+ : cct(cct), backend(driver), mask_bits(bits), match(match), pool(pool),
+ shard(shard), shard_prefix(make_shard_prefix(shard)) {
+ update_bits(mask_bits);
+ }
+
+ set<string> prefixes;
+ /// Update bits in case of pg split or merge
+ void update_bits(
+ uint32_t new_bits ///< [in] new split bits
+ ) {
+ mask_bits = new_bits;
+ set<string> _prefixes = hobject_t::get_prefixes(
+ mask_bits,
+ match,
+ pool);
+ prefixes.clear();
+ for (set<string>::iterator i = _prefixes.begin();
+ i != _prefixes.end();
+ ++i) {
+ prefixes.insert(shard_prefix + *i);
+ }
+ }
+
+ /// Update snaps for oid, empty new_snaps removes the mapping
+ int update_snaps(
+ const hobject_t &oid, ///< [in] oid to update
+ const std::set<snapid_t> &new_snaps, ///< [in] new snap set
+ const std::set<snapid_t> *old_snaps, ///< [in] old snaps (for debugging)
+ MapCacher::Transaction<std::string, bufferlist> *t ///< [out] transaction
+ ); ///@ return error, 0 on success
+
+ /// Add mapping for oid, must not already be mapped
+ void add_oid(
+ const hobject_t &oid, ///< [in] oid to add
+ const std::set<snapid_t>& new_snaps, ///< [in] snaps
+ MapCacher::Transaction<std::string, bufferlist> *t ///< [out] transaction
+ );
+
+ /// Returns first object with snap as a snap
+ int get_next_objects_to_trim(
+ snapid_t snap, ///< [in] snap to check
+ unsigned max, ///< [in] max to get
+ vector<hobject_t> *out ///< [out] next objects to trim (must be empty)
+ ); ///< @return error, -ENOENT if no more objects
+
+ /// Remove mapping for oid
+ int remove_oid(
+ const hobject_t &oid, ///< [in] oid to remove
+ MapCacher::Transaction<std::string, bufferlist> *t ///< [out] transaction
+ ); ///< @return error, -ENOENT if the object is not mapped
+
+ /// Get snaps for oid
+ int get_snaps(
+ const hobject_t &oid, ///< [in] oid to get snaps for
+ std::set<snapid_t> *snaps ///< [out] snaps
+ ); ///< @return error, -ENOENT if oid is not recorded
+};
+WRITE_CLASS_ENCODER(SnapMapper::object_snaps)
+
+#endif
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