Fix MDnsClient's cache entry cleanup logic.

net/dns/mdns_client_impl.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "net/dns/mdns_client_impl.h"
 
+#include <algorithm>
 #include <queue>
 
 #include "base/bind.h"
 #include "base/message_loop/message_loop_proxy.h"
 #include "base/stl_util.h"
+#include "base/time/clock.h"
 #include "base/time/default_clock.h"
 #include "base/time/time.h"
+#include "base/timer/timer.h"
 #include "net/base/dns_util.h"
 #include "net/base/net_errors.h"
 #include "net/base/net_log.h"
 #include "net/base/rand_callback.h"
 #include "net/dns/dns_protocol.h"
 #include "net/dns/record_rdata.h"
 #include "net/udp/datagram_socket.h"
 
 // TODO(gene): Remove this temporary method of disabling NSEC support once it
 // becomes clear whether this feature should be
@@ skipping 164 matching lines @@
 
 void MDnsConnection::OnDatagramReceived(
     DnsResponse* response,
     const IPEndPoint& recv_addr,
     int bytes_read) {
   // TODO(noamsml): More sophisticated error handling.
   DCHECK_GT(bytes_read, 0);
   delegate_->HandlePacket(response, bytes_read);
 }
 
-MDnsClientImpl::Core::Core() : connection_(new MDnsConnection(this)) {
+MDnsClientImpl::Core::Core()
+    : clock_(new base::DefaultClock),
+      cleanup_timer_(new base::Timer(false, false)),
+      connection_(new MDnsConnection(this)) {
 }
 
 MDnsClientImpl::Core::~Core() {
   STLDeleteValues(&listeners_);
 }
 
 bool MDnsClientImpl::Core::Init(MDnsSocketFactory* socket_factory) {
   return connection_->Init(socket_factory);
 }
 
@@ skipping 25 matching lines @@
   // TODO(noamsml): duplicate query suppression.
   if (!(response->flags() & dns_protocol::kFlagResponse))
     return;  // Message is a query. ignore it.
 
   DnsRecordParser parser = response->Parser();
   unsigned answer_count = response->answer_count() +
       response->additional_answer_count();
 
   for (unsigned i = 0; i < answer_count; i++) {
     offset = parser.GetOffset();
-    scoped_ptr<const RecordParsed> record = RecordParsed::CreateFrom(
-        &parser, base::Time::Now());
+    scoped_ptr<const RecordParsed> record =
+        RecordParsed::CreateFrom(&parser, clock_->Now());
 
     if (!record) {
       DVLOG(1) << "Could not understand an mDNS record.";
 
       if (offset == parser.GetOffset()) {
         DVLOG(1) << "Abandoned parsing the rest of the packet.";
         return;  // The parser did not advance, abort reading the packet.
       } else {
         continue;  // We may be able to extract other records from the packet.
       }
@@ skipping 32 matching lines @@
 }
 
 void MDnsClientImpl::Core::NotifyNsecRecord(const RecordParsed* record) {
   DCHECK_EQ(dns_protocol::kTypeNSEC, record->type());
   const NsecRecordRdata* rdata = record->rdata<NsecRecordRdata>();
   DCHECK(rdata);
 
   // Remove all cached records matching the nonexistent RR types.
   std::vector<const RecordParsed*> records_to_remove;
 
-  cache_.FindDnsRecords(0, record->name(), &records_to_remove,
-                        base::Time::Now());
+  cache_.FindDnsRecords(0, record->name(), &records_to_remove, clock_->Now());
 
   for (std::vector<const RecordParsed*>::iterator i = records_to_remove.begin();
        i != records_to_remove.end(); i++) {
     if ((*i)->type() == dns_protocol::kTypeNSEC)
       continue;
     if (!rdata->GetBit((*i)->type())) {
       scoped_ptr<const RecordParsed> record_removed = cache_.RemoveRecord((*i));
       DCHECK(record_removed);
       OnRecordRemoved(record_removed.get());
     }
   }
 
   // Alert all listeners waiting for the nonexistent RR types.
   ListenerMap::iterator i =
       listeners_.upper_bound(ListenerKey(record->name(), 0));
   for (; i != listeners_.end() && i->first.first == record->name(); i++) {
     if (!rdata->GetBit(i->first.second)) {
       FOR_EACH_OBSERVER(MDnsListenerImpl, *i->second, AlertNsecRecord());
     }
   }
 }
 
 void MDnsClientImpl::Core::OnConnectionError(int error) {
   // TODO(noamsml): On connection error, recreate connection and flush cache.
 }
 
+void MDnsClientImpl::Core::set_cleanup_timer_for_test(
+    scoped_ptr<base::Timer> timer) {
+  cleanup_timer_ = timer.Pass();
+}
+
+void MDnsClientImpl::Core::set_clock_for_test(scoped_ptr<base::Clock> clock) {
+  clock_ = clock.Pass();
+}
+
 void MDnsClientImpl::Core::AlertListeners(
     MDnsCache::UpdateType update_type,
     const ListenerKey& key,
     const RecordParsed* record) {
   ListenerMap::iterator listener_map_iterator = listeners_.find(key);
   if (listener_map_iterator == listeners_.end()) return;
 
   FOR_EACH_OBSERVER(MDnsListenerImpl, *listener_map_iterator->second,
                     HandleRecordUpdate(update_type, record));
 }
@@ skipping 37 matching lines @@
 void MDnsClientImpl::Core::CleanupObserverList(const ListenerKey& key) {
   ListenerMap::iterator found = listeners_.find(key);
   if (found != listeners_.end() && !found->second->might_have_observers()) {
     delete found->second;
     listeners_.erase(found);
   }
 }
 
 void MDnsClientImpl::Core::ScheduleCleanup(base::Time cleanup) {
   // Cleanup is already scheduled, no need to do anything.
-  if (cleanup == scheduled_cleanup_) return;
+  if (cleanup == scheduled_cleanup_) {
+    return;
+  }
   scheduled_cleanup_ = cleanup;
 
   // This cancels the previously scheduled cleanup.
-  cleanup_callback_.Reset(base::Bind(
-      &MDnsClientImpl::Core::DoCleanup, base::Unretained(this)));
+  cleanup_timer_->Stop();
 
   // If |cleanup| is empty, then no cleanup necessary.
   if (cleanup != base::Time()) {
-    base::MessageLoop::current()->PostDelayedTask(
-        FROM_HERE,
-        cleanup_callback_.callback(),
-        cleanup - base::Time::Now());
+    cleanup_timer_->Start(
+        FROM_HERE, std::max(base::TimeDelta(), cleanup - clock_->Now()),
+        base::Bind(&MDnsClientImpl::Core::DoCleanup, base::Unretained(this)));
   }
 }
 
 void MDnsClientImpl::Core::DoCleanup() {
-  cache_.CleanupRecords(base::Time::Now(), base::Bind(
-      &MDnsClientImpl::Core::OnRecordRemoved, base::Unretained(this)));
+  cache_.CleanupRecords(clock_->Now(),
+                        base::Bind(&MDnsClientImpl::Core::OnRecordRemoved,

[mark a. foltz, 2015/02/25 21:44:07]

What cancels this callback when MDnsClientImpl is deleted?

[Kevin M, 2015/02/26 01:04:40]

DoCleanup() can't be called if the MdnsClientImpl is deleted, because
MDnsCleanup::cleanup_timer_ will be deleted and unable to execute the DoCleanup
callback.

[mark a. foltz, 2015/02/26 01:18:03]

Acknowledged.

+                                   base::Unretained(this)));
 
   ScheduleCleanup(cache_.next_expiration());
 }
 
 void MDnsClientImpl::Core::OnRecordRemoved(
     const RecordParsed* record) {
   AlertListeners(MDnsCache::RecordRemoved,
                  ListenerKey(record->name(), record->type()), record);
 }
 
 void MDnsClientImpl::Core::QueryCache(
     uint16 rrtype, const std::string& name,
     std::vector<const RecordParsed*>* records) const {
-  cache_.FindDnsRecords(rrtype, name, records, base::Time::Now());
+  cache_.FindDnsRecords(rrtype, name, records, clock_->Now());
 }
 
 MDnsClientImpl::MDnsClientImpl() {
 }
 
 MDnsClientImpl::~MDnsClientImpl() {
 }
 
 bool MDnsClientImpl::StartListening(MDnsSocketFactory* socket_factory) {
   DCHECK(!core_.get());
@@ skipping 140 matching lines @@
       static_cast<int>(base::Time::kMillisecondsPerSecond *
                        kListenerRefreshRatio1 * ttl_));
 
   base::Time next_refresh2 = last_update_ + base::TimeDelta::FromMilliseconds(
       static_cast<int>(base::Time::kMillisecondsPerSecond *
                        kListenerRefreshRatio2 * ttl_));
 
   base::MessageLoop::current()->PostDelayedTask(
       FROM_HERE,
       next_refresh_.callback(),
       next_refresh1 - base::Time::Now());

[mark a. foltz, 2015/02/25 21:44:06]

If we are converting this class to use base::Clock, we should do it everywhere.

[Kevin M, 2015/02/26 01:04:40]

This required a bit of plumbing to route the Clock objects through to child
objects, but done.

 
   base::MessageLoop::current()->PostDelayedTask(
       FROM_HERE,
       next_refresh_.callback(),
       next_refresh2 - base::Time::Now());

[mark a. foltz, 2015/02/25 21:44:07]

Ditto.

[Kevin M, 2015/02/26 01:04:40]

Done.

 }
 
 void MDnsListenerImpl::DoRefresh() {
   client_->core()->SendQuery(rrtype_, name_);
 }
 
 MDnsTransactionImpl::MDnsTransactionImpl(
     uint16 rrtype,
     const std::string& name,
     int flags,
@@ skipping 134 matching lines @@
 
 void MDnsTransactionImpl::OnNsecRecord(const std::string& name, unsigned type) {
   TriggerCallback(RESULT_NSEC, NULL);
 }
 
 void MDnsTransactionImpl::OnCachePurged() {
   // TODO(noamsml): Cache purge situations not yet implemented
 }
 
 }  // namespace net