refactor: Modularize shamap and nodestore (#5668)

This change moves the shamap and nodestore from `xrpld` to `libxrpl`.

include/xrpl/shamap/FullBelowCache.h

@@ -0,0 +1,153 @@
+//------------------------------------------------------------------------------
+/*
+    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_FULLBELOWCACHE_H_INCLUDED
+#define RIPPLE_SHAMAP_FULLBELOWCACHE_H_INCLUDED
+
+#include <xrpl/basics/KeyCache.h>
+#include <xrpl/basics/TaggedCache.h>
+#include <xrpl/basics/base_uint.h>
+#include <xrpl/beast/insight/Collector.h>
+#include <xrpl/beast/utility/Journal.h>
+
+#include <atomic>
+#include <string>
+
+namespace ripple {
+
+namespace detail {
+
+/** Remembers which tree keys have all descendants resident.
+    This optimizes the process of acquiring a complete tree.
+*/
+class BasicFullBelowCache
+{
+private:
+    using CacheType = KeyCache;
+
+public:
+    enum { defaultCacheTargetSize = 0 };
+
+    using key_type = uint256;
+    using clock_type = typename CacheType::clock_type;
+
+    /** Construct the cache.
+
+        @param name A label for diagnostics and stats reporting.
+        @param collector The collector to use for reporting stats.
+        @param targetSize The cache target size.
+        @param targetExpirationSeconds The expiration time for items.
+    */
+    BasicFullBelowCache(
+        std::string const& name,
+        clock_type& clock,
+        beast::Journal j,
+        beast::insight::Collector::ptr const& collector =
+            beast::insight::NullCollector::New(),
+        std::size_t target_size = defaultCacheTargetSize,
+        std::chrono::seconds expiration = std::chrono::minutes{2})
+        : m_cache(name, target_size, expiration, clock, j, collector), m_gen(1)
+    {
+    }
+
+    /** Return the clock associated with the cache. */
+    clock_type&
+    clock()
+    {
+        return m_cache.clock();
+    }
+
+    /** Return the number of elements in the cache.
+        Thread safety:
+            Safe to call from any thread.
+    */
+    std::size_t
+    size() const
+    {
+        return m_cache.size();
+    }
+
+    /** Remove expired cache items.
+        Thread safety:
+            Safe to call from any thread.
+    */
+    void
+    sweep()
+    {
+        m_cache.sweep();
+    }
+
+    /** Refresh the last access time of an item, if it exists.
+        Thread safety:
+            Safe to call from any thread.
+        @param key The key to refresh.
+        @return `true` If the key exists.
+    */
+    bool
+    touch_if_exists(key_type const& key)
+    {
+        return m_cache.touch_if_exists(key);
+    }
+
+    /** Insert a key into the cache.
+        If the key already exists, the last access time will still
+        be refreshed.
+        Thread safety:
+            Safe to call from any thread.
+        @param key The key to insert.
+    */
+    void
+    insert(key_type const& key)
+    {
+        m_cache.insert(key);
+    }
+
+    /** generation determines whether cached entry is valid */
+    std::uint32_t
+    getGeneration(void) const
+    {
+        return m_gen;
+    }
+
+    void
+    clear()
+    {
+        m_cache.clear();
+        ++m_gen;
+    }
+
+    void
+    reset()
+    {
+        m_cache.clear();
+        m_gen = 1;
+    }
+
+private:
+    CacheType m_cache;
+    std::atomic<std::uint32_t> m_gen;
+};
+
+}  // namespace detail
+
+using FullBelowCache = detail::BasicFullBelowCache;
+
+}  // namespace ripple
+
+#endif