diff options
Diffstat (limited to 'src/crimson/os/seastore/cache.h')
| -rw-r--r-- | src/crimson/os/seastore/cache.h | 516 |
1 files changed, 516 insertions, 0 deletions
diff --git a/src/crimson/os/seastore/cache.h b/src/crimson/os/seastore/cache.h new file mode 100644 index 000000000..624272162 --- /dev/null +++ b/src/crimson/os/seastore/cache.h @@ -0,0 +1,516 @@ +// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*- +// vim: ts=8 sw=2 smarttab + +#pragma once + +#include <iostream> + +#include "seastar/core/shared_future.hh" + +#include "include/buffer.h" +#include "crimson/os/seastore/seastore_types.h" +#include "crimson/os/seastore/transaction.h" +#include "crimson/os/seastore/segment_manager.h" +#include "crimson/common/errorator.h" +#include "crimson/os/seastore/cached_extent.h" +#include "crimson/os/seastore/root_block.h" +#include "crimson/os/seastore/segment_cleaner.h" + +namespace crimson::os::seastore { + +/** + * Cache + * + * This component is responsible for buffer management, including + * transaction lifecycle. + * + * Seastore transactions are expressed as an atomic combination of + * 1) newly written blocks + * 2) logical mutations to existing physical blocks + * + * See record_t + * + * As such, any transaction has 3 components: + * 1) read_set: references to extents read during the transaction + * See Transaction::read_set + * 2) write_set: references to extents to be written as: + * a) new physical blocks, see Transaction::fresh_block_list + * b) mutations to existing physical blocks, + * see Transaction::mutated_block_list + * 3) retired_set: extent refs to be retired either due to 2b or + * due to releasing the extent generally. + + * In the case of 2b, the CachedExtent will have been copied into + * a fresh CachedExtentRef such that the source extent ref is present + * in the read set and the newly allocated extent is present in the + * write_set. + * + * A transaction has 3 phases: + * 1) construction: user calls Cache::get_transaction() and populates + * the returned transaction by calling Cache methods + * 2) submission: user calls Cache::try_start_transaction(). If + * succcessful, the user may construct a record and submit the + * transaction to the journal. + * 3) completion: once the transaction is durable, the user must call + * Cache::complete_transaction() with the block offset to complete + * the transaction. + * + * Internally, in phase 1, the fields in Transaction are filled in. + * - reads may block if the referenced extent is being written + * - once a read obtains a particular CachedExtentRef for a paddr_t, + * it'll always get the same one until overwritten + * - once a paddr_t is overwritten or written, subsequent reads of + * that addr will get the new ref + * + * In phase 2, if all extents in the read set are valid (not expired), + * we can commit (otherwise, we fail and the user must retry). + * - Expire all extents in the retired_set (they must all be valid) + * - Remove all extents in the retired_set from Cache::extents + * - Mark all extents in the write_set wait_io(), add promises to + * transaction + * - Merge Transaction::write_set into Cache::extents + * + * After phase 2, the user will submit the record to the journal. + * Once complete, we perform phase 3: + * - For each CachedExtent in block_list, call + * CachedExtent::complete_initial_write(paddr_t) with the block's + * final offset (inferred from the extent's position in the block_list + * and extent lengths). + * - For each block in mutation_list, call + * CachedExtent::delta_written(paddr_t) with the address of the start + * of the record + * - Complete all promises with the final record start paddr_t + */ +class Cache { +public: + Cache(SegmentManager &segment_manager); + ~Cache(); + + /** + * drop_from_cache + * + * Drop extent from cache. Intended for use when + * ref refers to a logically dead extent as during + * replay. + */ + void drop_from_cache(CachedExtentRef ref) { + remove_extent(ref); + } + + /// Declare ref retired in t + void retire_extent(Transaction &t, CachedExtentRef ref) { + t.add_to_retired_set(ref); + } + + /// Declare paddr retired in t, noop if not cached + using retire_extent_ertr = crimson::errorator< + crimson::ct_error::input_output_error>; + using retire_extent_ret = retire_extent_ertr::future<>; + retire_extent_ret retire_extent_if_cached( + Transaction &t, paddr_t addr); + + /** + * get_root + * + * returns ref to current root or t.root if modified in t + */ + using get_root_ertr = crimson::errorator< + crimson::ct_error::input_output_error>; + using get_root_ret = get_root_ertr::future<RootBlockRef>; + get_root_ret get_root(Transaction &t); + + /** + * get_root_fast + * + * returns t.root and assume it is already present/read in t + */ + RootBlockRef get_root_fast(Transaction &t) { + assert(t.root); + return t.root; + } + + /** + * get_extent + * + * returns ref to extent at offset~length of type T either from + * - extent_set if already in cache + * - disk + */ + using get_extent_ertr = crimson::errorator< + crimson::ct_error::input_output_error>; + template <typename T> + get_extent_ertr::future<TCachedExtentRef<T>> get_extent( + paddr_t offset, ///< [in] starting addr + segment_off_t length ///< [in] length + ) { + if (auto iter = extents.find_offset(offset); + iter != extents.end()) { + auto ret = TCachedExtentRef<T>(static_cast<T*>(&*iter)); + return ret->wait_io().then([ret=std::move(ret)]() mutable { + return get_extent_ertr::make_ready_future<TCachedExtentRef<T>>( + std::move(ret)); + }); + } else { + auto ref = CachedExtent::make_cached_extent_ref<T>( + alloc_cache_buf(length)); + ref->set_io_wait(); + ref->set_paddr(offset); + ref->state = CachedExtent::extent_state_t::CLEAN; + + return segment_manager.read( + offset, + length, + ref->get_bptr()).safe_then( + [this, ref=std::move(ref)]() mutable { + /* TODO: crc should be checked against LBA manager */ + ref->last_committed_crc = ref->get_crc32c(); + + ref->on_clean_read(); + ref->complete_io(); + add_extent(ref); + return get_extent_ertr::make_ready_future<TCachedExtentRef<T>>( + std::move(ref)); + }, + get_extent_ertr::pass_further{}, + crimson::ct_error::discard_all{}); + } + } + + /** + * get_extent_if_cached + * + * Returns extent at offset if in cache + */ + Transaction::get_extent_ret get_extent_if_cached( + Transaction &t, + paddr_t offset, + CachedExtentRef *out) { + auto result = t.get_extent(offset, out); + if (result != Transaction::get_extent_ret::ABSENT) { + return result; + } else if (auto iter = extents.find_offset(offset); + iter != extents.end()) { + if (out) + *out = &*iter; + return Transaction::get_extent_ret::PRESENT; + } else { + return Transaction::get_extent_ret::ABSENT; + } + } + + /** + * get_extent + * + * returns ref to extent at offset~length of type T either from + * - t if modified by t + * - extent_set if already in cache + * - disk + * + * t *must not* have retired offset + */ + template <typename T> + get_extent_ertr::future<TCachedExtentRef<T>> get_extent( + Transaction &t, ///< [in,out] current transaction + paddr_t offset, ///< [in] starting addr + segment_off_t length ///< [in] length + ) { + CachedExtentRef ret; + auto result = t.get_extent(offset, &ret); + if (result != Transaction::get_extent_ret::ABSENT) { + assert(result != Transaction::get_extent_ret::RETIRED); + return get_extent_ertr::make_ready_future<TCachedExtentRef<T>>( + ret->cast<T>()); + } else { + return get_extent<T>(offset, length).safe_then( + [&t](auto ref) mutable { + t.add_to_read_set(ref); + return get_extent_ertr::make_ready_future<TCachedExtentRef<T>>( + std::move(ref)); + }); + } + } + + /** + * get_extent_by_type + * + * Based on type, instantiate the correct concrete type + * and read in the extent at location offset~length. + */ + get_extent_ertr::future<CachedExtentRef> get_extent_by_type( + extent_types_t type, ///< [in] type tag + paddr_t offset, ///< [in] starting addr + laddr_t laddr, ///< [in] logical address if logical + segment_off_t length ///< [in] length + ); + + get_extent_ertr::future<CachedExtentRef> get_extent_by_type( + Transaction &t, + extent_types_t type, + paddr_t offset, + laddr_t laddr, + segment_off_t length) { + CachedExtentRef ret; + auto status = get_extent_if_cached(t, offset, &ret); + if (status == Transaction::get_extent_ret::RETIRED) { + return get_extent_ertr::make_ready_future<CachedExtentRef>(); + } else if (status == Transaction::get_extent_ret::PRESENT) { + return get_extent_ertr::make_ready_future<CachedExtentRef>(ret); + } else { + return get_extent_by_type(type, offset, laddr, length + ).safe_then([=, &t](CachedExtentRef ret) { + t.add_to_read_set(ret); + return get_extent_ertr::make_ready_future<CachedExtentRef>( + std::move(ret)); + }); + } + } + + /** + * get_extents + * + * returns refs to extents in extents from: + * - t if modified by t + * - extent_set if already in cache + * - disk + */ + template<typename T> + get_extent_ertr::future<t_pextent_list_t<T>> get_extents( + Transaction &t, ///< [in, out] current transaction + paddr_list_t &&extents ///< [in] extent list for lookup + ) { + auto retref = std::make_unique<t_pextent_list_t<T>>(); + auto &ret = *retref; + auto ext = std::make_unique<paddr_list_t>(std::move(extents)); + return crimson::do_for_each( + ext->begin(), + ext->end(), + [this, &t, &ret](auto &p) { + auto &[offset, len] = p; + return get_extent(t, offset, len).safe_then([&ret](auto cext) { + ret.push_back(std::move(cext)); + }); + }).safe_then([retref=std::move(retref), ext=std::move(ext)]() mutable { + return get_extent_ertr::make_ready_future<t_pextent_list_t<T>>( + std::move(*retref)); + }); + } + + /** + * alloc_new_extent + * + * Allocates a fresh extent. addr will be relative until commit. + */ + template <typename T> + TCachedExtentRef<T> alloc_new_extent( + Transaction &t, ///< [in, out] current transaction + segment_off_t length ///< [in] length + ) { + auto ret = CachedExtent::make_cached_extent_ref<T>( + alloc_cache_buf(length)); + t.add_fresh_extent(ret); + ret->state = CachedExtent::extent_state_t::INITIAL_WRITE_PENDING; + return ret; + } + + /** + * alloc_new_extent + * + * Allocates a fresh extent. addr will be relative until commit. + */ + CachedExtentRef alloc_new_extent_by_type( + Transaction &t, ///< [in, out] current transaction + extent_types_t type, ///< [in] type tag + segment_off_t length ///< [in] length + ); + + /** + * Allocates mutable buffer from extent_set on offset~len + * + * TODO: Note, currently all implementations literally copy the + * buffer. This needn't be true, CachedExtent implementations could + * choose to refer to the same buffer unmodified until commit and just + * buffer the mutations in an ancillary data structure. + * + * @param current transaction + * @param extent to duplicate + * @return mutable extent + */ + CachedExtentRef duplicate_for_write( + Transaction &t, ///< [in, out] current transaction + CachedExtentRef i ///< [in] ref to existing extent + ); + + /** + * try_construct_record + * + * First checks for conflicts. If a racing write has mutated/retired + * an extent mutated by this transaction, nullopt will be returned. + * + * Otherwise, a record will be returned valid for use with Journal. + */ + std::optional<record_t> try_construct_record( + Transaction &t ///< [in, out] current transaction + ); + + /** + * complete_commit + * + * Must be called upon completion of write. Releases blocks on mutating + * extents, fills in addresses, and calls relevant callbacks on fresh + * and mutated exents. + */ + void complete_commit( + Transaction &t, ///< [in, out] current transaction + paddr_t final_block_start, ///< [in] offset of initial block + journal_seq_t seq, ///< [in] journal commit seq + SegmentCleaner *cleaner=nullptr ///< [out] optional segment stat listener + ); + + /** + * init + */ + void init(); + + /** + * mkfs + * + * Alloc initial root node and add to t. The intention is for other + * components to use t to adjust the resulting root ref prior to commit. + */ + using mkfs_ertr = crimson::errorator< + crimson::ct_error::input_output_error>; + mkfs_ertr::future<> mkfs(Transaction &t); + + /** + * close + * + * TODO: should flush dirty blocks + */ + using close_ertr = crimson::errorator< + crimson::ct_error::input_output_error>; + close_ertr::future<> close(); + + /** + * replay_delta + * + * Intended for use in Journal::delta. For each delta, should decode delta, + * read relevant block from disk or cache (using correct type), and call + * CachedExtent::apply_delta marking the extent dirty. + */ + using replay_delta_ertr = crimson::errorator< + crimson::ct_error::input_output_error>; + using replay_delta_ret = replay_delta_ertr::future<>; + replay_delta_ret replay_delta( + journal_seq_t seq, + paddr_t record_block_base, + const delta_info_t &delta); + + /** + * init_cached_extents + * + * Calls passed lambda for each dirty cached block. Intended for use + * after replay to allow lba_manager (or w/e) to read in any ancestor + * blocks. + */ + using init_cached_extents_ertr = crimson::errorator< + crimson::ct_error::input_output_error>; + using init_cached_extents_ret = replay_delta_ertr::future<>; + template <typename F> + init_cached_extents_ret init_cached_extents( + Transaction &t, + F &&f) + { + std::vector<CachedExtentRef> dirty; + for (auto &e : extents) { + dirty.push_back(CachedExtentRef(&e)); + } + return seastar::do_with( + std::forward<F>(f), + std::move(dirty), + [&t](auto &f, auto &refs) mutable { + return crimson::do_for_each( + refs, + [&t, &f](auto &e) { return f(t, e); }); + }); + } + + /** + * update_extent_from_transaction + * + * Updates passed extent based on t. If extent has been retired, + * a null result will be returned. + */ + CachedExtentRef update_extent_from_transaction( + Transaction &t, + CachedExtentRef extent) { + if (extent->get_type() == extent_types_t::ROOT) { + if (t.root) { + return t.root; + } else { + return extent; + } + } else { + auto result = t.get_extent(extent->get_paddr(), &extent); + if (result == Transaction::get_extent_ret::RETIRED) { + return CachedExtentRef(); + } else { + return extent; + } + } + } + + /** + * print + * + * Dump summary of contents (TODO) + */ + std::ostream &print( + std::ostream &out) const { + return out; + } + + /// returns extents with dirty_from < seq + using get_next_dirty_extents_ertr = crimson::errorator<>; + using get_next_dirty_extents_ret = get_next_dirty_extents_ertr::future< + std::vector<CachedExtentRef>>; + get_next_dirty_extents_ret get_next_dirty_extents( + journal_seq_t seq); + +private: + SegmentManager &segment_manager; ///< ref to segment_manager + RootBlockRef root; ///< ref to current root + ExtentIndex extents; ///< set of live extents + + /** + * dirty + * + * holds refs to dirty extents. Ordered by CachedExtent::dirty_from. + */ + CachedExtent::list dirty; + + /// alloc buffer for cached extent + bufferptr alloc_cache_buf(size_t size) { + // TODO: memory pooling etc + auto bp = ceph::bufferptr( + buffer::create_page_aligned(size)); + bp.zero(); + return bp; + } + + /// Add extent to extents handling dirty and refcounting + void add_extent(CachedExtentRef ref); + + /// Mark exising extent ref dirty -- mainly for replay + void mark_dirty(CachedExtentRef ref); + + /// Add dirty extent to dirty list + void add_to_dirty(CachedExtentRef ref); + + /// Remove extent from extents handling dirty and refcounting + void remove_extent(CachedExtentRef ref); + + /// Replace prev with next + void replace_extent(CachedExtentRef next, CachedExtentRef prev); +}; + +} |