--- /dev/null
+// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
+// vim: ts=8 sw=2 smarttab
+
+#include "rgw_period_history.h"
+#include "rgw_rados.h"
+
+#include "include/assert.h"
+
+#define dout_subsys ceph_subsys_rgw
+
+#undef dout_prefix
+#define dout_prefix (*_dout << "rgw period history: ")
+
+/// an ordered history of consecutive periods
+class RGWPeriodHistory::History : public bi::avl_set_base_hook<> {
+ public:
+ std::deque<RGWPeriod> periods;
+
+ epoch_t get_oldest_epoch() const {
+ return periods.front().get_realm_epoch();
+ }
+ epoch_t get_newest_epoch() const {
+ return periods.back().get_realm_epoch();
+ }
+ bool contains(epoch_t epoch) const {
+ return get_oldest_epoch() <= epoch && epoch <= get_newest_epoch();
+ }
+ RGWPeriod& get(epoch_t epoch) {
+ return periods[epoch - get_oldest_epoch()];
+ }
+ const RGWPeriod& get(epoch_t epoch) const {
+ return periods[epoch - get_oldest_epoch()];
+ }
+ const std::string& get_predecessor_id() const {
+ return periods.front().get_predecessor();
+ }
+};
+
+/// value comparison for avl_set
+bool operator<(const RGWPeriodHistory::History& lhs,
+ const RGWPeriodHistory::History& rhs)
+{
+ return lhs.get_newest_epoch() < rhs.get_newest_epoch();
+}
+
+/// key-value comparison for avl_set
+struct NewestEpochLess {
+ bool operator()(const RGWPeriodHistory::History& value, epoch_t key) const {
+ return value.get_newest_epoch() < key;
+ }
+};
+
+
+using Cursor = RGWPeriodHistory::Cursor;
+
+const RGWPeriod& Cursor::get_period() const
+{
+ std::lock_guard<std::mutex> lock(*mutex);
+ return history->get(epoch);
+}
+bool Cursor::has_prev() const
+{
+ std::lock_guard<std::mutex> lock(*mutex);
+ return epoch > history->get_oldest_epoch();
+}
+bool Cursor::has_next() const
+{
+ std::lock_guard<std::mutex> lock(*mutex);
+ return epoch < history->get_newest_epoch();
+}
+
+bool operator==(const Cursor& lhs, const Cursor& rhs)
+{
+ return lhs.history == rhs.history && lhs.epoch == rhs.epoch;
+}
+
+bool operator!=(const Cursor& lhs, const Cursor& rhs)
+{
+ return !(lhs == rhs);
+}
+
+class RGWPeriodHistory::Impl final {
+ public:
+ Impl(CephContext* cct, Puller* puller, const RGWPeriod& current_period);
+ ~Impl();
+
+ Cursor get_current() const { return current_cursor; }
+ Cursor attach(RGWPeriod&& period);
+ Cursor insert(RGWPeriod&& period);
+ Cursor lookup(epoch_t realm_epoch);
+
+ private:
+ /// an intrusive set of histories, ordered by their newest epoch. although
+ /// the newest epoch of each history is mutable, the ordering cannot change
+ /// because we prevent the histories from overlapping
+ using Set = bi::avl_set<RGWPeriodHistory::History>;
+
+ /// insert the given period into the period history, creating new unconnected
+ /// histories or merging existing histories as necessary. expects the caller
+ /// to hold a lock on mutex. returns a valid cursor regardless of whether it
+ /// ends up in current_history, though cursors in other histories are only
+ /// valid within the context of the lock
+ Cursor insert_locked(RGWPeriod&& period);
+
+ /// merge the periods from the src history onto the end of the dst history,
+ /// and return an iterator to the merged history
+ Set::iterator merge(Set::iterator dst, Set::iterator src);
+
+ /// construct a Cursor object using Cursor's private constuctor
+ Cursor make_cursor(Set::const_iterator history, epoch_t epoch);
+
+ CephContext *const cct;
+ Puller *const puller; //< interface for pulling missing periods
+ Cursor current_cursor; //< Cursor to realm's current period
+
+ mutable std::mutex mutex; //< protects the histories
+
+ /// set of disjoint histories that are missing intermediate periods needed to
+ /// connect them together
+ Set histories;
+
+ /// iterator to the history that contains the realm's current period
+ Set::const_iterator current_history;
+};
+
+RGWPeriodHistory::Impl::Impl(CephContext* cct, Puller* puller,
+ const RGWPeriod& current_period)
+ : cct(cct), puller(puller)
+{
+ if (!current_period.get_id().empty()) {
+ // copy the current period into a new history
+ auto history = new History;
+ history->periods.push_back(current_period);
+
+ // insert as our current history
+ current_history = histories.insert(*history).first;
+
+ // get a cursor to the current period
+ current_cursor = make_cursor(current_history, current_period.get_realm_epoch());
+ }
+}
+
+RGWPeriodHistory::Impl::~Impl()
+{
+ // clear the histories and delete each entry
+ histories.clear_and_dispose(std::default_delete<History>{});
+}
+
+Cursor RGWPeriodHistory::Impl::attach(RGWPeriod&& period)
+{
+ if (current_history == histories.end()) {
+ return Cursor{-EINVAL};
+ }
+
+ const auto epoch = period.get_realm_epoch();
+
+ std::string predecessor_id;
+ for (;;) {
+ {
+ // hold the lock over insert, and while accessing the unsafe cursor
+ std::lock_guard<std::mutex> lock(mutex);
+
+ auto cursor = insert_locked(std::move(period));
+ if (!cursor) {
+ return cursor;
+ }
+ if (current_history->contains(epoch)) {
+ break; // the history is complete
+ }
+
+ // take the predecessor id of the most recent history
+ if (cursor.get_epoch() > current_cursor.get_epoch()) {
+ predecessor_id = cursor.history->get_predecessor_id();
+ } else {
+ predecessor_id = current_history->get_predecessor_id();
+ }
+ }
+
+ if (predecessor_id.empty()) {
+ lderr(cct) << "reached a period with an empty predecessor id" << dendl;
+ return Cursor{-EINVAL};
+ }
+
+ // pull the period outside of the lock
+ int r = puller->pull(predecessor_id, period);
+ if (r < 0) {
+ return Cursor{r};
+ }
+ }
+
+ // return a cursor to the requested period
+ return make_cursor(current_history, epoch);
+}
+
+Cursor RGWPeriodHistory::Impl::insert(RGWPeriod&& period)
+{
+ if (current_history == histories.end()) {
+ return Cursor{-EINVAL};
+ }
+
+ std::lock_guard<std::mutex> lock(mutex);
+
+ auto cursor = insert_locked(std::move(period));
+
+ if (cursor.get_error()) {
+ return cursor;
+ }
+ // we can only provide cursors that are safe to use outside of the mutex if
+ // they're within the current_history, because other histories can disappear
+ // in a merge. see merge() for the special handling of current_history
+ if (cursor.history == &*current_history) {
+ return cursor;
+ }
+ return Cursor{};
+}
+
+Cursor RGWPeriodHistory::Impl::lookup(epoch_t realm_epoch)
+{
+ if (current_history != histories.end() &&
+ current_history->contains(realm_epoch)) {
+ return make_cursor(current_history, realm_epoch);
+ }
+ return Cursor{};
+}
+
+Cursor RGWPeriodHistory::Impl::insert_locked(RGWPeriod&& period)
+{
+ auto epoch = period.get_realm_epoch();
+
+ // find the first history whose newest epoch comes at or after this period
+ auto i = histories.lower_bound(epoch, NewestEpochLess{});
+
+ if (i == histories.end()) {
+ // epoch is past the end of our newest history
+ auto last = --Set::iterator{i}; // last = i - 1
+
+ if (epoch == last->get_newest_epoch() + 1) {
+ // insert at the back of the last history
+ last->periods.emplace_back(std::move(period));
+ return make_cursor(last, epoch);
+ }
+
+ // create a new history for this period
+ auto history = new History;
+ history->periods.emplace_back(std::move(period));
+ histories.insert(last, *history);
+
+ i = Set::s_iterator_to(*history);
+ return make_cursor(i, epoch);
+ }
+
+ if (i->contains(epoch)) {
+ // already resident in this history
+ auto& existing = i->get(epoch);
+ // verify that the period ids match; otherwise we've forked the history
+ if (period.get_id() != existing.get_id()) {
+ lderr(cct) << "Got two different periods, " << period.get_id()
+ << " and " << existing.get_id() << ", with the same realm epoch "
+ << epoch << "! This indicates a fork in the period history." << dendl;
+ return Cursor{-EEXIST};
+ }
+ // update the existing period if we got a newer period epoch
+ if (period.get_epoch() > existing.get_epoch()) {
+ existing = std::move(period);
+ }
+ return make_cursor(i, epoch);
+ }
+
+ if (epoch + 1 == i->get_oldest_epoch()) {
+ // insert at the front of this history
+ i->periods.emplace_front(std::move(period));
+
+ // try to merge with the previous history
+ if (i != histories.begin()) {
+ auto prev = --Set::iterator{i};
+ if (epoch == prev->get_newest_epoch() + 1) {
+ i = merge(prev, i);
+ }
+ }
+ return make_cursor(i, epoch);
+ }
+
+ if (i != histories.begin()) {
+ auto prev = --Set::iterator{i};
+ if (epoch == prev->get_newest_epoch() + 1) {
+ // insert at the back of the previous history
+ prev->periods.emplace_back(std::move(period));
+ return make_cursor(prev, epoch);
+ }
+ }
+
+ // create a new history for this period
+ auto history = new History;
+ history->periods.emplace_back(std::move(period));
+ histories.insert(i, *history);
+
+ i = Set::s_iterator_to(*history);
+ return make_cursor(i, epoch);
+}
+
+RGWPeriodHistory::Impl::Set::iterator
+RGWPeriodHistory::Impl::merge(Set::iterator dst, Set::iterator src)
+{
+ assert(dst->get_newest_epoch() + 1 == src->get_oldest_epoch());
+
+ // always merge into current_history
+ if (src == current_history) {
+ // move the periods from dst onto the front of src
+ src->periods.insert(src->periods.begin(),
+ std::make_move_iterator(dst->periods.begin()),
+ std::make_move_iterator(dst->periods.end()));
+ histories.erase_and_dispose(dst, std::default_delete<History>{});
+ return src;
+ }
+
+ // move the periods from src onto the end of dst
+ dst->periods.insert(dst->periods.end(),
+ std::make_move_iterator(src->periods.begin()),
+ std::make_move_iterator(src->periods.end()));
+ histories.erase_and_dispose(src, std::default_delete<History>{});
+ return dst;
+}
+
+Cursor RGWPeriodHistory::Impl::make_cursor(Set::const_iterator history,
+ epoch_t epoch) {
+ return Cursor{&*history, &mutex, epoch};
+}
+
+
+RGWPeriodHistory::RGWPeriodHistory(CephContext* cct, Puller* puller,
+ const RGWPeriod& current_period)
+ : impl(new Impl(cct, puller, current_period)) {}
+
+RGWPeriodHistory::~RGWPeriodHistory() = default;
+
+Cursor RGWPeriodHistory::get_current() const
+{
+ return impl->get_current();
+}
+Cursor RGWPeriodHistory::attach(RGWPeriod&& period)
+{
+ return impl->attach(std::move(period));
+}
+Cursor RGWPeriodHistory::insert(RGWPeriod&& period)
+{
+ return impl->insert(std::move(period));
+}
+Cursor RGWPeriodHistory::lookup(epoch_t realm_epoch)
+{
+ return impl->lookup(realm_epoch);
+}
Code Review / stor4nfv.git / blobdiff