lending_tx_list.go

// Copyright 2016 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.

package core

import (
	"container/heap"
	"sort"

	"github.com/XinFinOrg/XDC-Subnet/core/types"
)

// txSortedMap is a nonce->transaction hash map with a heap based index to allow
// iterating over the contents in a nonce-incrementing way.
type lendingtxSortedMap struct {
	items map[uint64]*types.LendingTransaction // Hash map storing the transaction data
	index *nonceHeap                           // Heap of nonces of all the stored transactions (non-strict mode)
	cache types.LendingTransactions            // Cache of the transactions already sorted
}

// newTxSortedMap creates a new nonce-sorted transaction map.
func newLendingTxSortedMap() *lendingtxSortedMap {
	return &lendingtxSortedMap{
		items: make(map[uint64]*types.LendingTransaction),
		index: new(nonceHeap),
	}
}

// Get retrieves the current transactions associated with the given nonce.
func (m *lendingtxSortedMap) Get(nonce uint64) *types.LendingTransaction {
	return m.items[nonce]
}

// Put inserts a new transaction into the map, also updating the map's nonce
// index. If a transaction already exists with the same nonce, it's overwritten.
func (m *lendingtxSortedMap) Put(tx *types.LendingTransaction) {
	nonce := tx.Nonce()
	if m.items[nonce] == nil {
		heap.Push(m.index, nonce)
	}
	m.items[nonce], m.cache = tx, nil
}

// Forward removes all transactions from the map with a nonce lower than the
// provided threshold. Every removed transaction is returned for any post-removal
// maintenance.
func (m *lendingtxSortedMap) Forward(threshold uint64) types.LendingTransactions {
	var removed types.LendingTransactions

	// Pop off heap items until the threshold is reached
	for m.index.Len() > 0 && (*m.index)[0] < threshold {
		nonce := heap.Pop(m.index).(uint64)
		removed = append(removed, m.items[nonce])
		delete(m.items, nonce)
	}
	// If we had a cached lending transaction, shift the front
	if m.cache != nil {
		m.cache = m.cache[len(removed):]
	}
	return removed
}

// Filter iterates over the list of transactions and removes all of them for which
// the specified function evaluates to true.
func (m *lendingtxSortedMap) Filter(filter func(*types.LendingTransaction) bool) types.LendingTransactions {
	var removed types.LendingTransactions

	// Collect all the transactions to filter out
	for nonce, tx := range m.items {
		if filter(tx) {
			removed = append(removed, tx)
			delete(m.items, nonce)
		}
	}
	// If transactions were removed, the heap and cache are ruined
	if len(removed) > 0 {
		*m.index = make([]uint64, 0, len(m.items))
		for nonce := range m.items {
			*m.index = append(*m.index, nonce)
		}
		heap.Init(m.index)

		m.cache = nil
	}
	return removed
}

// Cap places a hard limit on the number of items, returning all transactions
// exceeding that limit.
func (m *lendingtxSortedMap) Cap(threshold int) types.LendingTransactions {
	// Short circuit if the number of items is under the limit
	if len(m.items) <= threshold {
		return nil
	}
	// Otherwise gather and drop the highest nonce'd transactions
	var drops types.LendingTransactions

	sort.Sort(*m.index)
	for size := len(m.items); size > threshold; size-- {
		drops = append(drops, m.items[(*m.index)[size-1]])
		delete(m.items, (*m.index)[size-1])
	}
	*m.index = (*m.index)[:threshold]
	heap.Init(m.index)

	// If we had a cache, shift the back
	if m.cache != nil {
		m.cache = m.cache[:len(m.cache)-len(drops)]
	}
	return drops
}

// Remove deletes a transaction from the maintained map, returning whether the
// transaction was found.
func (m *lendingtxSortedMap) Remove(nonce uint64) bool {
	// Short circuit if no transaction is present
	_, ok := m.items[nonce]
	if !ok {
		return false
	}
	// Otherwise delete the transaction and fix the heap index
	for i := 0; i < m.index.Len(); i++ {
		if (*m.index)[i] == nonce {
			heap.Remove(m.index, i)
			break
		}
	}
	delete(m.items, nonce)
	m.cache = nil

	return true
}

// Ready retrieves a sequentially increasing list of transactions starting at the
// provided nonce that is ready for processing. The returned transactions will be
// removed from the list.
//
// Note, all transactions with nonces lower than start will also be returned to
// prevent getting into and invalid state. This is not something that should ever
// happen but better to be self correcting than failing!
func (m *lendingtxSortedMap) Ready(start uint64) types.LendingTransactions {
	// Short circuit if no transactions are available
	if m.index.Len() == 0 || (*m.index)[0] > start {
		return nil
	}
	// Otherwise start accumulating incremental transactions
	var ready types.LendingTransactions
	for next := (*m.index)[0]; m.index.Len() > 0 && (*m.index)[0] == next; next++ {
		ready = append(ready, m.items[next])
		delete(m.items, next)
		heap.Pop(m.index)
	}
	m.cache = nil

	return ready
}

// Len returns the length of the transaction map.
func (m *lendingtxSortedMap) Len() int {
	return len(m.items)
}

// Flatten creates a nonce-sorted slice of transactions based on the loosely
// sorted internal representation. The result of the sorting is cached in case
// it's requested again before any modifications are made to the contents.
func (m *lendingtxSortedMap) Flatten() types.LendingTransactions {
	// If the sorting was not cached yet, create and cache it
	if m.cache == nil {
		m.cache = make(types.LendingTransactions, 0, len(m.items))
		for _, tx := range m.items {
			m.cache = append(m.cache, tx)
		}
		sort.Sort(types.LendingTxByNonce(m.cache))
	}
	// Copy the cache to prevent accidental modifications
	txs := make(types.LendingTransactions, len(m.cache))
	copy(txs, m.cache)
	return txs
}

// txList is a "list" of transactions belonging to an account, sorted by account
// nonce. The same type can be used both for storing contiguous transactions for
// the executable/pending queue; and for storing gapped transactions for the non-
// executable/future queue, with minor behavioral changes.
type lendingtxList struct {
	strict bool                // Whether nonces are strictly continuous or not
	txs    *lendingtxSortedMap // Heap indexed sorted hash map of the transactions
}

// newTxList create a new transaction list for maintaining nonce-indexable fast,
// gapped, sortable transaction lists.
func newLendingTxList(strict bool) *lendingtxList {
	return &lendingtxList{
		strict: strict,
		txs:    newLendingTxSortedMap(),
	}
}

// Overlaps returns whether the transaction specified has the same nonce as one
// already contained within the list.
func (l *lendingtxList) Overlaps(tx *types.LendingTransaction) bool {
	return l.txs.Get(tx.Nonce()) != nil
}

// Add tries to insert a new transaction into the list, returning whether the
// transaction was accepted, and if yes, any previous transaction it replaced.
//
// If the new transaction is accepted into the list, the lists' cost and gas
// thresholds are also potentially updated.
func (l *lendingtxList) Add(tx *types.LendingTransaction) (bool, *types.LendingTransaction) {
	// If there's an older better transaction, abort
	old := l.txs.Get(tx.Nonce())
	if old != nil {
		l.txs.Put(tx)
		return true, old
	}
	l.txs.Put(tx)
	return true, nil
}

// Forward removes all transactions from the list with a nonce lower than the
// provided threshold. Every removed transaction is returned for any post-removal
// maintenance.
func (l *lendingtxList) Forward(threshold uint64) types.LendingTransactions {
	return l.txs.Forward(threshold)
}

// Cap places a hard limit on the number of items, returning all transactions
// exceeding that limit.
func (l *lendingtxList) Cap(threshold int) types.LendingTransactions {
	return l.txs.Cap(threshold)
}

// Remove deletes a transaction from the maintained list, returning whether the
// transaction was found, and also returning any transaction invalidated due to
// the deletion (strict mode only).
func (l *lendingtxList) Remove(tx *types.LendingTransaction) (bool, types.LendingTransactions) {
	// Remove the transaction from the set
	nonce := tx.Nonce()
	if removed := l.txs.Remove(nonce); !removed {
		return false, nil
	}
	// In strict mode, filter out non-executable transactions
	if l.strict {
		return true, l.txs.Filter(func(tx *types.LendingTransaction) bool { return tx.Nonce() > nonce })
	}
	return true, nil
}

// Ready retrieves a sequentially increasing list of transactions starting at the
// provided nonce that is ready for processing. The returned transactions will be
// removed from the list.
//
// Note, all transactions with nonces lower than start will also be returned to
// prevent getting into and invalid state. This is not something that should ever
// happen but better to be self correcting than failing!
func (l *lendingtxList) Ready(start uint64) types.LendingTransactions {
	return l.txs.Ready(start)
}

// Len returns the length of the transaction list.
func (l *lendingtxList) Len() int {
	return l.txs.Len()
}

// Empty returns whether the list of transactions is empty or not.
func (l *lendingtxList) Empty() bool {
	return l.Len() == 0
}

// Flatten creates a nonce-sorted slice of transactions based on the loosely
// sorted internal representation. The result of the sorting is cached in case
// it's requested again before any modifications are made to the contents.
func (l *lendingtxList) Flatten() types.LendingTransactions {
	return l.txs.Flatten()
}