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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) 2016 Red Hat
+ *
+ * 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 PGTRANSACTION_H
+#define PGTRANSACTION_H
+
+#include <map>
+#include <memory>
+#include <boost/optional.hpp>
+
+#include "common/hobject.h"
+#include "osd/osd_types.h"
+#include "osd/osd_internal_types.h"
+#include "common/interval_map.h"
+#include "common/inline_variant.h"
+
+/**
+ * This class represents transactions which can be submitted to
+ * a PGBackend. For expediency, there are some constraints on
+ * the operations submitted:
+ * 1) Rename sources may only be referenced prior to the rename
+ * operation to the destination.
+ * 2) The graph formed by edges of source->destination for clones
+ * (Create) and Renames must be acyclic.
+ * 3) clone_range sources must not be modified by the same
+ * transaction
+ */
+class PGTransaction {
+public:
+ map<hobject_t, ObjectContextRef> obc_map;
+
+ class ObjectOperation {
+ public:
+ struct Init
+ {
+ struct None {};
+ struct Create {};
+ struct Clone {
+ hobject_t source;
+ };
+ struct Rename {
+ hobject_t source; // must be temp object
+ };
+ };
+ using InitType = boost::variant<
+ Init::None,
+ Init::Create,
+ Init::Clone,
+ Init::Rename>;
+
+ InitType init_type = Init::None();
+ bool delete_first = false;
+
+ /**
+ * is_none() && is_delete() indicates that we are deleting an
+ * object which already exists and not recreating it. delete_first means
+ * that the transaction logically removes the object.
+
+ * There are really 4 cases:
+
+ * 1) We are modifying an existing object (is_none() &&
+ * !is_delete())
+ * a) If it's an append, we just write into the log entry the old size
+ * b) If it's an actual overwrite, we save the old versions of the
+ * extents being overwritten and write those offsets into the log
+ * entry
+ * 2) We are removing and then recreating an object (!is_none() && is_delete())
+ * -- stash
+ * 3) We are removing an object (is_none() && is_delete()) -- stash
+ * 4) We are creating an object (!is_none() && !is_delete()) -- create (no
+ * stash)
+ *
+ * Create, Clone, Rename are the three ways we can recreate it.
+ * ECBackend transaction planning needs this context
+ * to figure out how to perform the transaction.
+ */
+ bool deletes_first() const {
+ return delete_first;
+ }
+ bool is_delete() const {
+ return boost::get<Init::None>(&init_type) != nullptr && delete_first;
+ }
+ bool is_none() const {
+ return boost::get<Init::None>(&init_type) != nullptr && !delete_first;
+ }
+ bool is_fresh_object() const {
+ return boost::get<Init::None>(&init_type) == nullptr;
+ }
+ bool is_rename() const {
+ return boost::get<Init::Rename>(&init_type) != nullptr;
+ }
+ bool has_source(hobject_t *source = nullptr) const {
+ return match(
+ init_type,
+ [&](const Init::Clone &op) -> bool {
+ if (source)
+ *source = op.source;
+ return true;
+ },
+ [&](const Init::Rename &op) -> bool {
+ if (source)
+ *source = op.source;
+ return true;
+ },
+ [&](const Init::None &) -> bool { return false; },
+ [&](const Init::Create &) -> bool { return false; });
+ }
+
+ bool clear_omap = false;
+
+ /**
+ * truncate
+ * <lowest, last> ?
+ *
+ * truncate is represented as a pair because in the event of
+ * multiple truncates within a single transaction we need to
+ * remember the lowest truncate and the final object size
+ * (the last truncate). We also adjust the buffers map
+ * to account for truncates overriding previous writes */
+ boost::optional<pair<uint64_t, uint64_t> > truncate = boost::none;
+
+ std::map<string, boost::optional<bufferlist> > attr_updates;
+
+ enum class OmapUpdateType {Remove, Insert};
+ std::vector<std::pair<OmapUpdateType, bufferlist> > omap_updates;
+
+ boost::optional<bufferlist> omap_header;
+
+ /// (old, new) -- only valid with no truncate or buffer updates
+ boost::optional<pair<set<snapid_t>, set<snapid_t> > > updated_snaps;
+
+ struct alloc_hint_t {
+ uint64_t expected_object_size;
+ uint64_t expected_write_size;
+ uint32_t flags;
+ };
+ boost::optional<alloc_hint_t> alloc_hint;
+
+ struct BufferUpdate {
+ struct Write {
+ bufferlist buffer;
+ uint32_t fadvise_flags;
+ };
+ struct Zero {
+ uint64_t len;
+ };
+ struct CloneRange {
+ hobject_t from;
+ uint64_t offset;
+ uint64_t len;
+ };
+ };
+ using BufferUpdateType = boost::variant<
+ BufferUpdate::Write,
+ BufferUpdate::Zero,
+ BufferUpdate::CloneRange>;
+
+ private:
+ struct SplitMerger {
+ BufferUpdateType split(
+ uint64_t offset,
+ uint64_t len,
+ const BufferUpdateType &bu) const {
+ return match(
+ bu,
+ [&](const BufferUpdate::Write &w) -> BufferUpdateType {
+ bufferlist bl;
+ bl.substr_of(w.buffer, offset, len);
+ return BufferUpdate::Write{bl, w.fadvise_flags};
+ },
+ [&](const BufferUpdate::Zero &) -> BufferUpdateType {
+ return BufferUpdate::Zero{len};
+ },
+ [&](const BufferUpdate::CloneRange &c) -> BufferUpdateType {
+ return BufferUpdate::CloneRange{c.from, c.offset + offset, len};
+ });
+ }
+ uint64_t length(
+ const BufferUpdateType &left) const {
+ return match(
+ left,
+ [&](const BufferUpdate::Write &w) -> uint64_t {
+ return w.buffer.length();
+ },
+ [&](const BufferUpdate::Zero &z) -> uint64_t {
+ return z.len;
+ },
+ [&](const BufferUpdate::CloneRange &c) -> uint64_t {
+ return c.len;
+ });
+ }
+ bool can_merge(
+ const BufferUpdateType &left,
+ const BufferUpdateType &right) const {
+ return match(
+ left,
+ [&](const BufferUpdate::Write &w) -> bool {
+ auto r = boost::get<BufferUpdate::Write>(&right);
+ return r != nullptr && (w.fadvise_flags == r->fadvise_flags);
+ },
+ [&](const BufferUpdate::Zero &) -> bool {
+ auto r = boost::get<BufferUpdate::Zero>(&right);
+ return r != nullptr;
+ },
+ [&](const BufferUpdate::CloneRange &c) -> bool {
+ return false;
+ });
+ }
+ BufferUpdateType merge(
+ BufferUpdateType &&left,
+ BufferUpdateType &&right) const {
+ return match(
+ left,
+ [&](const BufferUpdate::Write &w) -> BufferUpdateType {
+ auto r = boost::get<BufferUpdate::Write>(&right);
+ ceph_assert(r && w.fadvise_flags == r->fadvise_flags);
+ bufferlist bl = w.buffer;
+ bl.append(r->buffer);
+ return BufferUpdate::Write{bl, w.fadvise_flags};
+ },
+ [&](const BufferUpdate::Zero &z) -> BufferUpdateType {
+ auto r = boost::get<BufferUpdate::Zero>(&right);
+ ceph_assert(r);
+ return BufferUpdate::Zero{z.len + r->len};
+ },
+ [&](const BufferUpdate::CloneRange &c) -> BufferUpdateType {
+ ceph_abort_msg("violates can_merge condition");
+ return left;
+ });
+ }
+ };
+ public:
+ using buffer_update_type = interval_map<
+ uint64_t, BufferUpdateType, SplitMerger>;
+ buffer_update_type buffer_updates;
+
+ friend class PGTransaction;
+ };
+ map<hobject_t, ObjectOperation> op_map;
+private:
+ ObjectOperation &get_object_op_for_modify(const hobject_t &hoid) {
+ auto &op = op_map[hoid];
+ ceph_assert(!op.is_delete());
+ return op;
+ }
+ ObjectOperation &get_object_op(const hobject_t &hoid) {
+ return op_map[hoid];
+ }
+public:
+ void add_obc(
+ ObjectContextRef obc) {
+ ceph_assert(obc);
+ obc_map[obc->obs.oi.soid] = obc;
+ }
+ /// Sets up state for new object
+ void create(
+ const hobject_t &hoid
+ ) {
+ auto &op = op_map[hoid];
+ ceph_assert(op.is_none() || op.is_delete());
+ op.init_type = ObjectOperation::Init::Create();
+ }
+
+ /// Sets up state for target cloned from source
+ void clone(
+ const hobject_t &target, ///< [in] obj to clone to
+ const hobject_t &source ///< [in] obj to clone from
+ ) {
+ auto &op = op_map[target];
+ ceph_assert(op.is_none() || op.is_delete());
+ op.init_type = ObjectOperation::Init::Clone{source};
+ }
+
+ /// Sets up state for target renamed from source
+ void rename(
+ const hobject_t &target, ///< [in] to, must not exist, be non-temp
+ const hobject_t &source ///< [in] source (must be a temp object)
+ ) {
+ ceph_assert(source.is_temp());
+ ceph_assert(!target.is_temp());
+ auto &op = op_map[target];
+ ceph_assert(op.is_none() || op.is_delete());
+
+ bool del_first = op.is_delete();
+ auto iter = op_map.find(source);
+ if (iter != op_map.end()) {
+ op = iter->second;
+ op_map.erase(iter);
+ op.delete_first = del_first;
+ }
+
+ op.init_type = ObjectOperation::Init::Rename{source};
+ }
+
+ /// Remove -- must not be called on rename target
+ void remove(
+ const hobject_t &hoid ///< [in] obj to remove
+ ) {
+ auto &op = get_object_op_for_modify(hoid);
+ if (!op.is_fresh_object()) {
+ ceph_assert(!op.updated_snaps);
+ op = ObjectOperation();
+ op.delete_first = true;
+ } else {
+ ceph_assert(!op.is_rename());
+ op_map.erase(hoid); // make it a noop if it's a fresh object
+ }
+ }
+
+ void update_snaps(
+ const hobject_t &hoid, ///< [in] object for snaps
+ const set<snapid_t> &old_snaps,///< [in] old snaps value
+ const set<snapid_t> &new_snaps ///< [in] new snaps value
+ ) {
+ auto &op = get_object_op(hoid);
+ ceph_assert(!op.updated_snaps);
+ ceph_assert(op.buffer_updates.empty());
+ ceph_assert(!op.truncate);
+ op.updated_snaps = make_pair(
+ old_snaps,
+ new_snaps);
+ }
+
+ /// Clears, truncates
+ void omap_clear(
+ const hobject_t &hoid ///< [in] object to clear omap
+ ) {
+ auto &op = get_object_op_for_modify(hoid);
+ op.clear_omap = true;
+ op.omap_updates.clear();
+ op.omap_header = boost::none;
+ }
+ void truncate(
+ const hobject_t &hoid, ///< [in] object
+ uint64_t off ///< [in] offset to truncate to
+ ) {
+ auto &op = get_object_op_for_modify(hoid);
+ ceph_assert(!op.updated_snaps);
+ op.buffer_updates.erase(
+ off,
+ std::numeric_limits<uint64_t>::max() - off);
+ if (!op.truncate || off < op.truncate->first) {
+ op.truncate = std::pair<uint64_t, uint64_t>(off, off);
+ } else {
+ op.truncate->second = off;
+ }
+ }
+
+ /// Attr ops
+ void setattrs(
+ const hobject_t &hoid, ///< [in] object to write
+ map<string, bufferlist> &attrs ///< [in] attrs, may be cleared
+ ) {
+ auto &op = get_object_op_for_modify(hoid);
+ for (auto &&i: attrs) {
+ auto& d = op.attr_updates[i.first];
+ d = i.second;
+ d->rebuild();
+ }
+ }
+ void setattr(
+ const hobject_t &hoid, ///< [in] object to write
+ const string &attrname, ///< [in] attr to write
+ bufferlist &bl ///< [in] val to write, may be claimed
+ ) {
+ auto &op = get_object_op_for_modify(hoid);
+ auto& d = op.attr_updates[attrname];
+ d = bl;
+ d->rebuild();
+ }
+ void rmattr(
+ const hobject_t &hoid, ///< [in] object to write
+ const string &attrname ///< [in] attr to remove
+ ) {
+ auto &op = get_object_op_for_modify(hoid);
+ op.attr_updates[attrname] = boost::none;
+ }
+
+ /// set alloc hint
+ void set_alloc_hint(
+ const hobject_t &hoid, ///< [in] object (must exist)
+ uint64_t expected_object_size, ///< [in]
+ uint64_t expected_write_size,
+ uint32_t flags
+ ) {
+ auto &op = get_object_op_for_modify(hoid);
+ op.alloc_hint = ObjectOperation::alloc_hint_t{
+ expected_object_size, expected_write_size, flags};
+ }
+
+ /// Buffer updates
+ void write(
+ const hobject_t &hoid, ///< [in] object to write
+ uint64_t off, ///< [in] off at which to write
+ uint64_t len, ///< [in] len to write from bl
+ bufferlist &bl, ///< [in] bl to write will be claimed to len
+ uint32_t fadvise_flags = 0 ///< [in] fadvise hint
+ ) {
+ auto &op = get_object_op_for_modify(hoid);
+ ceph_assert(!op.updated_snaps);
+ ceph_assert(len > 0);
+ ceph_assert(len == bl.length());
+ op.buffer_updates.insert(
+ off,
+ len,
+ ObjectOperation::BufferUpdate::Write{bl, fadvise_flags});
+ }
+ void clone_range(
+ const hobject_t &from, ///< [in] from
+ const hobject_t &to, ///< [in] to
+ uint64_t fromoff, ///< [in] offset
+ uint64_t len, ///< [in] len
+ uint64_t tooff ///< [in] offset
+ ) {
+ auto &op = get_object_op_for_modify(to);
+ ceph_assert(!op.updated_snaps);
+ op.buffer_updates.insert(
+ tooff,
+ len,
+ ObjectOperation::BufferUpdate::CloneRange{from, fromoff, len});
+ }
+ void zero(
+ const hobject_t &hoid, ///< [in] object
+ uint64_t off, ///< [in] offset to start zeroing at
+ uint64_t len ///< [in] amount to zero
+ ) {
+ auto &op = get_object_op_for_modify(hoid);
+ ceph_assert(!op.updated_snaps);
+ op.buffer_updates.insert(
+ off,
+ len,
+ ObjectOperation::BufferUpdate::Zero{len});
+ }
+
+ /// Omap updates
+ void omap_setkeys(
+ const hobject_t &hoid, ///< [in] object to write
+ bufferlist &keys_bl ///< [in] encoded map<string, bufferlist>
+ ) {
+ auto &op = get_object_op_for_modify(hoid);
+ op.omap_updates.emplace_back(
+ make_pair(
+ ObjectOperation::OmapUpdateType::Insert,
+ keys_bl));
+ }
+ void omap_setkeys(
+ const hobject_t &hoid, ///< [in] object to write
+ map<string, bufferlist> &keys ///< [in] omap keys, may be cleared
+ ) {
+ bufferlist bl;
+ encode(keys, bl);
+ omap_setkeys(hoid, bl);
+ }
+ void omap_rmkeys(
+ const hobject_t &hoid, ///< [in] object to write
+ bufferlist &keys_bl ///< [in] encode set<string>
+ ) {
+ auto &op = get_object_op_for_modify(hoid);
+ op.omap_updates.emplace_back(
+ make_pair(
+ ObjectOperation::OmapUpdateType::Remove,
+ keys_bl));
+ }
+ void omap_rmkeys(
+ const hobject_t &hoid, ///< [in] object to write
+ set<string> &keys ///< [in] omap keys, may be cleared
+ ) {
+ bufferlist bl;
+ encode(keys, bl);
+ omap_rmkeys(hoid, bl);
+ }
+ void omap_setheader(
+ const hobject_t &hoid, ///< [in] object to write
+ bufferlist &header ///< [in] header
+ ) {
+ auto &op = get_object_op_for_modify(hoid);
+ op.omap_header = header;
+ }
+
+ bool empty() const {
+ return op_map.empty();
+ }
+
+ uint64_t get_bytes_written() const {
+ uint64_t ret = 0;
+ for (auto &&i: op_map) {
+ for (auto &&j: i.second.buffer_updates) {
+ ret += j.get_len();
+ }
+ }
+ return ret;
+ }
+
+ void nop(
+ const hobject_t &hoid ///< [in] obj to which we are doing nothing
+ ) {
+ get_object_op_for_modify(hoid);
+ }
+
+ /* Calls t() on all pair<hobject_t, ObjectOperation> & such that clone/rename
+ * sinks are always called before clone sources
+ *
+ * TODO: add a fast path for the single object case and possibly the single
+ * object clone from source case (make_writeable made a clone).
+ *
+ * This structure only requires that the source->sink graph be acyclic.
+ * This is much more general than is actually required by PrimaryLogPG.
+ * Only 4 flavors of multi-object transactions actually happen:
+ * 1) rename temp -> object for copyfrom
+ * 2) clone head -> clone, modify head for make_writeable on normal head write
+ * 3) clone clone -> head for rollback
+ * 4) 2 + 3
+ *
+ * We can bypass the below logic for single object transactions trivially
+ * (including case 1 above since temp doesn't show up again).
+ * For 2-3, we could add something ad-hoc to ensure that they happen in the
+ * right order, but it actually seems easier to just do the graph construction.
+ */
+ template <typename T>
+ void safe_create_traverse(T &&t) {
+ map<hobject_t, list<hobject_t>> dgraph;
+ list<hobject_t> stack;
+
+ // Populate stack with roots, dgraph with edges
+ for (auto &&opair: op_map) {
+ hobject_t source;
+ if (opair.second.has_source(&source)) {
+ auto &l = dgraph[source];
+ if (l.empty() && !op_map.count(source)) {
+ /* Source oids not in op_map need to be added as roots
+ * (but only once!) */
+ stack.push_back(source);
+ }
+ l.push_back(opair.first);
+ } else {
+ stack.push_back(opair.first);
+ }
+ }
+
+ /* Why don't we need to worry about accessing the same node
+ * twice? dgraph nodes always have in-degree at most 1 because
+ * the inverse graph nodes (source->dest) can have out-degree
+ * at most 1 (only one possible source). We do a post-order
+ * depth-first traversal here to ensure we call f on children
+ * before parents.
+ */
+ while (!stack.empty()) {
+ hobject_t &cur = stack.front();
+ auto diter = dgraph.find(cur);
+ if (diter == dgraph.end()) {
+ /* Leaf: pop and call t() */
+ auto opiter = op_map.find(cur);
+ if (opiter != op_map.end())
+ t(*opiter);
+ stack.pop_front();
+ } else {
+ /* Internal node: push children onto stack, remove edge,
+ * recurse. When this node is encountered again, it'll
+ * be a leaf */
+ ceph_assert(!diter->second.empty());
+ stack.splice(stack.begin(), diter->second);
+ dgraph.erase(diter);
+ }
+ }
+ }
+};
+using PGTransactionUPtr = std::unique_ptr<PGTransaction>;
+
+#endif
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-02 17:11:42 +0000