SHAMap.h

//------------------------------------------------------------------------------
/*
    This file is part of rippled: https://github.com/ripple/rippled
    Copyright (c) 2012, 2013 Ripple Labs Inc.
 
    Permission to use, copy, modify, and/or distribute this software for any
    purpose  with  or without fee is hereby granted, provided that the above
    copyright notice and this permission notice appear in all copies.
 
    THE  SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
    WITH  REGARD  TO  THIS  SOFTWARE  INCLUDING  ALL  IMPLIED  WARRANTIES  OF
    MERCHANTABILITY  AND  FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
    ANY  SPECIAL ,  DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
    WHATSOEVER  RESULTING  FROM  LOSS  OF USE, DATA OR PROFITS, WHETHER IN AN
    ACTION  OF  CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
    OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
//==============================================================================
 
#ifndef RIPPLE_SHAMAP_SHAMAP_H_INCLUDED
#define RIPPLE_SHAMAP_SHAMAP_H_INCLUDED
 
#include <ripple/basics/UnorderedContainers.h>
#include <ripple/beast/utility/Journal.h>
#include <ripple/nodestore/Database.h>
#include <ripple/nodestore/NodeObject.h>
#include <ripple/shamap/Family.h>
#include <ripple/shamap/FullBelowCache.h>
#include <ripple/shamap/SHAMapAddNode.h>
#include <ripple/shamap/SHAMapInnerNode.h>
#include <ripple/shamap/SHAMapItem.h>
#include <ripple/shamap/SHAMapLeafNode.h>
#include <ripple/shamap/SHAMapMissingNode.h>
#include <ripple/shamap/SHAMapTreeNode.h>
#include <ripple/shamap/TreeNodeCache.h>
#include <cassert>
#include <stack>
#include <vector>
 
namespace ripple {
 
class SHAMapNodeID;
class SHAMapSyncFilter;
 
enum class SHAMapState {
    Modifying = 0,
 
    Immutable = 1,
 
    Synching = 2,
 
    Invalid = 3,
};
 
class SHAMap
{
private:
    Family& f_;
    beast::Journal journal_;
 
    std::uint32_t cowid_ = 1;
 
    std::uint32_t ledgerSeq_ = 0;
 
    std::shared_ptr<SHAMapTreeNode> root_;
    mutable SHAMapState state_;
    SHAMapType const type_;
    bool backed_ = true;         // Map is backed by the database
    mutable bool full_ = false;  // Map is believed complete in database
 
public:
    static inline constexpr unsigned int branchFactor =
        SHAMapInnerNode::branchFactor;
 
    static inline constexpr unsigned int leafDepth = 64;
 
    using DeltaItem = std::pair<
        std::shared_ptr<SHAMapItem const>,
        std::shared_ptr<SHAMapItem const>>;
    using Delta = std::map<uint256, DeltaItem>;
 
    SHAMap(SHAMap const&) = delete;
    SHAMap&
    operator=(SHAMap const&) = delete;
 
    // build new map
    SHAMap(SHAMapType t, Family& f);
 
    SHAMap(SHAMapType t, uint256 const& hash, Family& f);
 
    ~SHAMap() = default;
 
    Family const&
    family() const
    {
        return f_;
    }
 
    Family&
    family()
    {
        return f_;
    }
 
    //--------------------------------------------------------------------------
 
    class const_iterator;
 
    const_iterator
    begin() const;
    const_iterator
    end() const;
 
    //--------------------------------------------------------------------------
 
    // Returns a new map that's a snapshot of this one.
    // Handles copy on write for mutable snapshots.
    std::shared_ptr<SHAMap>
    snapShot(bool isMutable) const;
 
    /*  Mark this SHAMap as "should be full", indicating
        that the local server wants all the corresponding nodes
        in durable storage.
    */
    void
    setFull();
 
    void
    setLedgerSeq(std::uint32_t lseq);
 
    bool
    fetchRoot(SHAMapHash const& hash, SHAMapSyncFilter* filter);
 
    // normal hash access functions
 
    bool
    hasItem(uint256 const& id) const;
 
    bool
    delItem(uint256 const& id);
 
    bool
    addItem(SHAMapNodeType type, SHAMapItem&& i);
 
    SHAMapHash
    getHash() const;
 
    // save a copy if you have a temporary anyway
    bool
    updateGiveItem(SHAMapNodeType type, std::shared_ptr<SHAMapItem const>);
 
    bool
    addGiveItem(SHAMapNodeType type, std::shared_ptr<SHAMapItem const> item);
 
    // Save a copy if you need to extend the life
    // of the SHAMapItem beyond this SHAMap
    std::shared_ptr<SHAMapItem const> const&
    peekItem(uint256 const& id) const;
    std::shared_ptr<SHAMapItem const> const&
    peekItem(uint256 const& id, SHAMapHash& hash) const;
 
    // traverse functions
    const_iterator
    upper_bound(uint256 const& id) const;
 
    void
    visitNodes(std::function<bool(SHAMapTreeNode&)> const& function) const;
 
    void
    visitDifferences(
        SHAMap const* have,
        std::function<bool(SHAMapTreeNode const&)>) const;
 
    void
    visitLeaves(
        std::function<void(std::shared_ptr<SHAMapItem const> const&)> const&)
        const;
 
    // comparison/sync functions
 
    std::vector<std::pair<SHAMapNodeID, uint256>>
    getMissingNodes(int maxNodes, SHAMapSyncFilter* filter);
 
    bool
    getNodeFat(
        SHAMapNodeID const& wanted,
        std::vector<SHAMapNodeID>& nodeIDs,
        std::vector<Blob>& rawNodes,
        bool fatLeaves,
        std::uint32_t depth) const;
 
    void
    serializeRoot(Serializer& s) const;
 
    SHAMapAddNode
    addRootNode(
        SHAMapHash const& hash,
        Slice const& rootNode,
        SHAMapSyncFilter* filter);
    SHAMapAddNode
    addKnownNode(
        SHAMapNodeID const& nodeID,
        Slice const& rawNode,
        SHAMapSyncFilter* filter);
 
    // status functions
    void
    setImmutable();
    bool
    isSynching() const;
    void
    setSynching();
    void
    clearSynching();
    bool
    isValid() const;
 
    // caution: otherMap must be accessed only by this function
    // return value: true=successfully completed, false=too different
    bool
    compare(SHAMap const& otherMap, Delta& differences, int maxCount) const;
 
    int
    unshare();
 
    int
    flushDirty(NodeObjectType t);
 
    void
    walkMap(std::vector<SHAMapMissingNode>& missingNodes, int maxMissing) const;
    bool
    deepCompare(SHAMap& other) const;  // Intended for debug/test only
 
    void
    setUnbacked();
 
    void
    dump(bool withHashes = false) const;
    void
    invariants() const;
 
private:
    using SharedPtrNodeStack =
        std::stack<std::pair<std::shared_ptr<SHAMapTreeNode>, SHAMapNodeID>>;
    using DeltaRef = std::pair<
        std::shared_ptr<SHAMapItem const> const&,
        std::shared_ptr<SHAMapItem const> const&>;
 
    // tree node cache operations
    std::shared_ptr<SHAMapTreeNode>
    cacheLookup(SHAMapHash const& hash) const;
    void
    canonicalize(SHAMapHash const& hash, std::shared_ptr<SHAMapTreeNode>&)
        const;
 
    // database operations
    std::shared_ptr<SHAMapTreeNode>
    fetchNodeFromDB(SHAMapHash const& hash) const;
    std::shared_ptr<SHAMapTreeNode>
    fetchNodeNT(SHAMapHash const& hash) const;
    std::shared_ptr<SHAMapTreeNode>
    fetchNodeNT(SHAMapHash const& hash, SHAMapSyncFilter* filter) const;
    std::shared_ptr<SHAMapTreeNode>
    fetchNode(SHAMapHash const& hash) const;
    std::shared_ptr<SHAMapTreeNode>
    checkFilter(SHAMapHash const& hash, SHAMapSyncFilter* filter) const;
 
    void
    dirtyUp(
        SharedPtrNodeStack& stack,
        uint256 const& target,
        std::shared_ptr<SHAMapTreeNode> terminal);
 
    SHAMapLeafNode*
    walkTowardsKey(uint256 const& id, SharedPtrNodeStack* stack = nullptr)
        const;
    SHAMapLeafNode*
    findKey(uint256 const& id) const;
 
    template <class Node>
    std::shared_ptr<Node>
    unshareNode(std::shared_ptr<Node>, SHAMapNodeID const& nodeID);
 
    template <class Node>
    std::shared_ptr<Node>
    preFlushNode(std::shared_ptr<Node> node) const;
 
    std::shared_ptr<SHAMapTreeNode>
    writeNode(NodeObjectType t, std::shared_ptr<SHAMapTreeNode> node) const;
 
    SHAMapLeafNode*
    firstBelow(
        std::shared_ptr<SHAMapTreeNode>,
        SharedPtrNodeStack& stack,
        int branch = 0) const;
 
    // Simple descent
    // Get a child of the specified node
    SHAMapTreeNode*
    descend(SHAMapInnerNode*, int branch) const;
    SHAMapTreeNode*
    descendThrow(SHAMapInnerNode*, int branch) const;
    std::shared_ptr<SHAMapTreeNode>
    descend(std::shared_ptr<SHAMapInnerNode> const&, int branch) const;
    std::shared_ptr<SHAMapTreeNode>
    descendThrow(std::shared_ptr<SHAMapInnerNode> const&, int branch) const;
 
    // Descend with filter
    // If pending, callback is called as if it called fetchNodeNT
    using descendCallback =
        std::function<void(std::shared_ptr<SHAMapTreeNode>, SHAMapHash const&)>;
    SHAMapTreeNode*
    descendAsync(
        SHAMapInnerNode* parent,
        int branch,
        SHAMapSyncFilter* filter,
        bool& pending,
        descendCallback&&) const;
 
    std::pair<SHAMapTreeNode*, SHAMapNodeID>
    descend(
        SHAMapInnerNode* parent,
        SHAMapNodeID const& parentID,
        int branch,
        SHAMapSyncFilter* filter) const;
 
    // Non-storing
    // Does not hook the returned node to its parent
    std::shared_ptr<SHAMapTreeNode>
    descendNoStore(std::shared_ptr<SHAMapInnerNode> const&, int branch) const;
 
    std::shared_ptr<SHAMapItem const> const&
    onlyBelow(SHAMapTreeNode*) const;
 
    bool
    hasInnerNode(SHAMapNodeID const& nodeID, SHAMapHash const& hash) const;
    bool
    hasLeafNode(uint256 const& tag, SHAMapHash const& hash) const;
 
    SHAMapLeafNode const*
    peekFirstItem(SharedPtrNodeStack& stack) const;
    SHAMapLeafNode const*
    peekNextItem(uint256 const& id, SharedPtrNodeStack& stack) const;
    bool
    walkBranch(
        SHAMapTreeNode* node,
        std::shared_ptr<SHAMapItem const> const& otherMapItem,
        bool isFirstMap,
        Delta& differences,
        int& maxCount) const;
    int
    walkSubTree(bool doWrite, NodeObjectType t);
 
    // Structure to track information about call to
    // getMissingNodes while it's in progress
    struct MissingNodes
    {
        MissingNodes() = delete;
        MissingNodes(const MissingNodes&) = delete;
        MissingNodes&
        operator=(const MissingNodes&) = delete;
 
        // basic parameters
        int max_;
        SHAMapSyncFilter* filter_;
        int const maxDefer_;
        std::uint32_t generation_;
 
        // nodes we have discovered to be missing
        std::vector<std::pair<SHAMapNodeID, uint256>> missingNodes_;
        std::set<SHAMapHash> missingHashes_;
 
        // nodes we are in the process of traversing
        using StackEntry = std::tuple<
            SHAMapInnerNode*,  // pointer to the node
            SHAMapNodeID,      // the node's ID
            int,               // while child we check first
            int,               // which child we check next
            bool>;             // whether we've found any missing children yet
 
        // We explicitly choose to specify the use of std::deque here, because
        // we need to ensure that pointers and/or references to existing
        // elements will not be invalidated during the course of element
        // insertion and removal. Containers that do not offer this guarantee,
        // such as std::vector, can't be used here.
        std::stack<StackEntry, std::deque<StackEntry>> stack_;
 
        // nodes we may have acquired from deferred reads
        using DeferredNode = std::tuple<
            SHAMapInnerNode*,                  // parent node
            SHAMapNodeID,                      // parent node ID
            int,                               // branch
            std::shared_ptr<SHAMapTreeNode>>;  // node
 
        int deferred_;
        std::mutex deferLock_;
        std::condition_variable deferCondVar_;
        std::vector<DeferredNode> finishedReads_;
 
        // nodes we need to resume after we get their children from deferred
        // reads
        std::map<SHAMapInnerNode*, SHAMapNodeID> resumes_;
 
        MissingNodes(
            int max,
            SHAMapSyncFilter* filter,
            int maxDefer,
            std::uint32_t generation)
            : max_(max)
            , filter_(filter)
            , maxDefer_(maxDefer)
            , generation_(generation)
            , deferred_(0)
        {
            missingNodes_.reserve(max);
            finishedReads_.reserve(maxDefer);
        }
    };
 
    // getMissingNodes helper functions
    void
    gmn_ProcessNodes(MissingNodes&, MissingNodes::StackEntry& node);
    void
    gmn_ProcessDeferredReads(MissingNodes&);
 
    // fetch from DB helper function
    std::shared_ptr<SHAMapTreeNode>
    finishFetch(
        SHAMapHash const& hash,
        std::shared_ptr<NodeObject> const& object) const;
};
 
inline void
SHAMap::setFull()
{
    full_ = true;
}
 
inline void
SHAMap::setLedgerSeq(std::uint32_t lseq)
{
    ledgerSeq_ = lseq;
}
 
inline void
SHAMap::setImmutable()
{
    assert(state_ != SHAMapState::Invalid);
    state_ = SHAMapState::Immutable;
}
 
inline bool
SHAMap::isSynching() const
{
    return state_ == SHAMapState::Synching;
}
 
inline void
SHAMap::setSynching()
{
    state_ = SHAMapState::Synching;
}
 
inline void
SHAMap::clearSynching()
{
    state_ = SHAMapState::Modifying;
}
 
inline bool
SHAMap::isValid() const
{
    return state_ != SHAMapState::Invalid;
}
 
inline void
SHAMap::setUnbacked()
{
    backed_ = false;
}
 
//------------------------------------------------------------------------------
 
class SHAMap::const_iterator
{
public:
    using iterator_category = std::forward_iterator_tag;
    using difference_type = std::ptrdiff_t;
    using value_type = SHAMapItem;
    using reference = value_type const&;
    using pointer = value_type const*;
 
private:
    SharedPtrNodeStack stack_;
    SHAMap const* map_ = nullptr;
    pointer item_ = nullptr;
 
public:
    const_iterator() = delete;
 
    const_iterator(const_iterator const& other) = default;
    const_iterator&
    operator=(const_iterator const& other) = default;
 
    ~const_iterator() = default;
 
    reference
    operator*() const;
    pointer
    operator->() const;
 
    const_iterator&
    operator++();
    const_iterator
    operator++(int);
 
private:
    explicit const_iterator(SHAMap const* map);
    const_iterator(SHAMap const* map, std::nullptr_t);
    const_iterator(SHAMap const* map, pointer item, SharedPtrNodeStack&& stack);
 
    friend bool
    operator==(const_iterator const& x, const_iterator const& y);
    friend class SHAMap;
};
 
inline SHAMap::const_iterator::const_iterator(SHAMap const* map) : map_(map)
{
    assert(map_ != nullptr);
 
    if (auto temp = map_->peekFirstItem(stack_))
        item_ = temp->peekItem().get();
}
 
inline SHAMap::const_iterator::const_iterator(SHAMap const* map, std::nullptr_t)
    : map_(map)
{
}
 
inline SHAMap::const_iterator::const_iterator(
    SHAMap const* map,
    pointer item,
    SharedPtrNodeStack&& stack)
    : stack_(std::move(stack)), map_(map), item_(item)
{
}
 
inline SHAMap::const_iterator::reference
SHAMap::const_iterator::operator*() const
{
    return *item_;
}
 
inline SHAMap::const_iterator::pointer
SHAMap::const_iterator::operator->() const
{
    return item_;
}
 
inline SHAMap::const_iterator&
SHAMap::const_iterator::operator++()
{
    if (auto temp = map_->peekNextItem(item_->key(), stack_))
        item_ = temp->peekItem().get();
    else
        item_ = nullptr;
    return *this;
}
 
inline SHAMap::const_iterator
SHAMap::const_iterator::operator++(int)
{
    auto tmp = *this;
    ++(*this);
    return tmp;
}
 
inline bool
operator==(SHAMap::const_iterator const& x, SHAMap::const_iterator const& y)
{
    assert(x.map_ == y.map_);
    return x.item_ == y.item_;
}
 
inline bool
operator!=(SHAMap::const_iterator const& x, SHAMap::const_iterator const& y)
{
    return !(x == y);
}
 
inline SHAMap::const_iterator
SHAMap::begin() const
{
    return const_iterator(this);
}
 
inline SHAMap::const_iterator
SHAMap::end() const
{
    return const_iterator(this, nullptr);
}
 
}  // namespace ripple
 
#endif