/
typecache.go
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/
typecache.go
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// Copyright 2015 The Vanadium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package rpc
import (
"fmt"
"sync"
"v.io/v23/context"
"v.io/v23/flow"
"v.io/v23/vom"
"v.io/x/lib/vlog"
)
type typeCacheEntry struct {
enc *vom.TypeEncoder
dec *vom.TypeDecoder
cancel context.CancelFunc
writer bool
ready chan struct{}
}
const typeCacheCollectInterval = 1000
type typeCache struct {
mu sync.Mutex
flows map[flow.ManagedConn]*typeCacheEntry
writes int
}
func newTypeCache() *typeCache {
return &typeCache{flows: make(map[flow.ManagedConn]*typeCacheEntry)}
}
func (tc *typeCache) writer(c flow.ManagedConn) (write func(flow.Flow, context.CancelFunc)) {
tc.mu.Lock()
tce := tc.flows[c]
if tce == nil {
tce = &typeCacheEntry{ready: make(chan struct{})}
tc.flows[c] = tce
}
if !tce.writer {
// TODO(mattr): This is a very course garbage collection policy.
// Every 1000 connections we clean out expired entries.
if tc.writes++; tc.writes%typeCacheCollectInterval == 0 {
go tc.collect()
}
tce.writer = true
write = func(f flow.Flow, c context.CancelFunc) {
if f != nil {
tce.cancel = c
tce.enc = vom.NewTypeEncoder(f)
tce.dec = vom.NewTypeDecoder(f)
tce.dec.Start() // Stopped in collect()
} else {
vlog.InfoStack(false)
vlog.Infof("closing ready chan for nil flow")
c()
}
close(tce.ready)
}
}
tc.mu.Unlock()
return
}
func (tc *typeCache) get(ctx *context.T, c flow.ManagedConn) (*vom.TypeEncoder, *vom.TypeDecoder, error) {
tc.mu.Lock()
tce := tc.flows[c]
if tce == nil {
tce = &typeCacheEntry{ready: make(chan struct{})}
tc.flows[c] = tce
}
tc.mu.Unlock()
select {
case <-c.Closed():
return nil, nil, errTypeFlowFailure.Errorf(ctx, "type flow could not be constructed: %v", fmt.Errorf("closed"))
case <-ctx.Done():
return nil, nil, ctx.Err()
case <-tce.ready:
if tce.enc == nil || tce.dec == nil {
var err error
if tce.enc == nil {
err = fmt.Errorf("nil encoder")
}
if tce.dec == nil {
err = fmt.Errorf("nil decoder")
}
if tce.enc == nil && tce.dec == nil {
err = fmt.Errorf("nil encoder & decoder")
}
return nil, nil, errTypeFlowFailure.Errorf(ctx, "type flow could not be constructed: %v", err)
}
}
return tce.enc, tce.dec, nil
}
func (tc *typeCache) collect() {
tc.mu.Lock()
conns := make([]flow.ManagedConn, len(tc.flows))
i := 0
for c := range tc.flows {
conns[i] = c
i++
}
tc.mu.Unlock()
last := 0
for _, c := range conns {
select {
case <-c.Closed():
conns[last] = c
last++
default:
}
}
if last > 0 {
tc.mu.Lock()
for idx := 0; idx < last; idx++ {
conn := conns[idx]
tce := tc.flows[conn]
if tce != nil {
if tce.cancel != nil {
tce.cancel()
}
if tce.dec != nil {
tce.dec.Stop()
}
delete(tc.flows, conn)
}
}
tc.mu.Unlock()
}
}
func (tc *typeCache) close() {
tc.mu.Lock()
for _, tce := range tc.flows {
if tce != nil {
if tce.cancel != nil {
tce.cancel()
}
if tce.dec != nil {
tce.dec.Stop()
}
}
}
tc.mu.Unlock()
}