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193 lines
5.1 KiB
193 lines
5.1 KiB
package mempool
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import (
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"container/list"
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"sync"
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"sync/atomic"
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"github.com/tendermint/go-clist"
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. "github.com/tendermint/go-common"
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"github.com/tendermint/tendermint/proxy"
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"github.com/tendermint/tendermint/types"
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tmsp "github.com/tendermint/tmsp/types"
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)
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/*
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The mempool pushes new txs onto the proxyAppConn.
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It gets a stream of (req, res) tuples from the proxy.
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The memool stores good txs in a concurrent linked-list.
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Multiple concurrent go-routines can traverse this linked-list
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safely by calling .NextWait() on each element.
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So we have several go-routines:
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1. Consensus calling Update() and Reap() synchronously
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2. Many mempool reactor's peer routines calling CheckTx()
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3. Many mempool reactor's peer routines traversing the txs linked list
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4. Another goroutine calling GarbageCollectTxs() periodically
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To manage these goroutines, there are three methods of locking.
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1. Mutations to the linked-list is protected by an internal mtx (CList is goroutine-safe)
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2. Mutations to the linked-list elements are atomic
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3. CheckTx() calls can be paused upon Update() and Reap(), protected by .proxyMtx
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Garbage collection of old elements from mempool.txs is handlde via
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the DetachPrev() call, which makes old elements not reachable by
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peer broadcastTxRoutine() automatically garbage collected.
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*/
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const cacheSize = 100000
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type Mempool struct {
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proxyMtx sync.Mutex
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proxyAppConn proxy.AppConn
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txs *clist.CList // concurrent linked-list of good txs
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counter int64 // simple incrementing counter
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height int // the last block Update()'d to
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// Keep a cache of already-seen txs.
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// This reduces the pressure on the proxyApp.
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cacheMap map[string]struct{}
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cacheList *list.List
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}
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func NewMempool(proxyAppConn proxy.AppConn) *Mempool {
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mempool := &Mempool{
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proxyAppConn: proxyAppConn,
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txs: clist.New(),
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counter: 0,
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height: 0,
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cacheMap: make(map[string]struct{}, cacheSize),
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cacheList: list.New(),
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}
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proxyAppConn.SetResponseCallback(mempool.resCb)
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return mempool
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}
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// Return the first element of mem.txs for peer goroutines to call .NextWait() on.
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// Blocks until txs has elements.
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func (mem *Mempool) TxsFrontWait() *clist.CElement {
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return mem.txs.FrontWait()
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}
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// Try a new transaction in the mempool.
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// Potentially blocking if we're blocking on Update() or Reap().
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func (mem *Mempool) CheckTx(tx types.Tx) (err error) {
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mem.proxyMtx.Lock()
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defer mem.proxyMtx.Unlock()
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// CACHE
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if _, exists := mem.cacheMap[string(tx)]; exists {
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return nil
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}
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if mem.cacheList.Len() >= cacheSize {
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popped := mem.cacheList.Front()
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poppedTx := popped.Value.(types.Tx)
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delete(mem.cacheMap, string(poppedTx))
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mem.cacheList.Remove(popped)
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}
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mem.cacheMap[string(tx)] = struct{}{}
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mem.cacheList.PushBack(tx)
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// END CACHE
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if err = mem.proxyAppConn.Error(); err != nil {
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return err
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}
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mem.proxyAppConn.CheckTxAsync(tx)
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return nil
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}
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// TMSP callback function
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func (mem *Mempool) resCb(req tmsp.Request, res tmsp.Response) {
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switch res := res.(type) {
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case tmsp.ResponseCheckTx:
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reqCheckTx := req.(tmsp.RequestCheckTx)
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if res.RetCode == tmsp.RetCodeOK {
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mem.counter++
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memTx := &mempoolTx{
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counter: mem.counter,
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height: int64(mem.height),
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tx: reqCheckTx.TxBytes,
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}
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mem.txs.PushBack(memTx)
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} else {
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// ignore bad transaction
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// TODO: handle other retcodes
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}
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default:
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// ignore other messages
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}
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}
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// Get the valid transactions remaining
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func (mem *Mempool) Reap() ([]types.Tx, error) {
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mem.proxyMtx.Lock()
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defer mem.proxyMtx.Unlock()
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txs := mem.collectTxs()
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return txs, nil
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}
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func (mem *Mempool) collectTxs() []types.Tx {
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txs := make([]types.Tx, 0, mem.txs.Len())
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for e := mem.txs.Front(); e != nil; e = e.Next() {
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memTx := e.Value.(*mempoolTx)
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txs = append(txs, memTx.tx)
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}
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return txs
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}
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// Tell mempool that these txs were committed.
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// Mempool will discard these txs.
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// NOTE: this should be called *after* block is committed by consensus.
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func (mem *Mempool) Update(height int, txs []types.Tx) error {
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mem.proxyMtx.Lock()
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defer mem.proxyMtx.Unlock()
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// First, create a lookup map of txns in new txs.
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txsMap := make(map[string]struct{})
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for _, tx := range txs {
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txsMap[string(tx)] = struct{}{}
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}
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// Set height
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mem.height = height
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// Remove transactions that are already in txs.
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mem.filterTxs(txsMap)
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return nil
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}
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func (mem *Mempool) filterTxs(blockTxsMap map[string]struct{}) []types.Tx {
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goodTxs := make([]types.Tx, 0, mem.txs.Len())
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for e := mem.txs.Front(); e != nil; e = e.Next() {
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memTx := e.Value.(*mempoolTx)
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if _, ok := blockTxsMap[string(memTx.tx)]; ok {
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// Remove the tx since already in block.
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mem.txs.Remove(e)
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e.DetachPrev()
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continue
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}
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// Good tx!
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goodTxs = append(goodTxs, memTx.tx)
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}
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return goodTxs
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}
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//--------------------------------------------------------------------------------
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// A transaction that successfully ran
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type mempoolTx struct {
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counter int64 // a simple incrementing counter
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height int64 // height that this tx had been validated in
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tx types.Tx //
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}
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func (memTx *mempoolTx) Height() int {
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return int(atomic.LoadInt64(&memTx.height))
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}
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