Reduce delay in tracker request

We eliminated 1 second delay between completion of name resolution for
tracker request and time when it is actually issued.  We also elimited
1 second delay after last torrent download exists and it is told to
DHTInteractionCommand.

src/DHTInteractionCommand.cc

@@ -54,6 +54,7 @@
 #include "UDPTrackerRequest.h"
 #include "fmt.h"
 #include "wallclock.h"
+#include "TrackerWatcherCommand.h"
 
 namespace aria2 {
 
@@ -66,6 +67,7 @@ DHTInteractionCommand::DHTInteractionCommand(cuid_t cuid, DownloadEngine* e)
       receiver_{nullptr},
       taskQueue_{nullptr}
 {
+  setStatusRealtime();
 }
 
 DHTInteractionCommand::~DHTInteractionCommand()
@@ -96,10 +98,12 @@ bool DHTInteractionCommand::execute()
   // needs this.
   if (e_->getRequestGroupMan()->downloadFinished() ||
       (e_->isHaltRequested() && udpTrackerClient_->getNumWatchers() == 0)) {
+    A2_LOG_DEBUG("DHTInteractionCommand exiting");
     return true;
   }
   else if (e_->isForceHaltRequested()) {
     udpTrackerClient_->failAll();
+    A2_LOG_DEBUG("DHTInteractionCommand exiting");
     return true;
   }
 
@@ -122,8 +126,18 @@ bool DHTInteractionCommand::execute()
       }
       else {
         // this may be udp tracker response. nothrow.
-        udpTrackerClient_->receiveReply(data.data(), length, remoteAddr,
-                                        remotePort, global::wallclock());
+        std::shared_ptr<UDPTrackerRequest> req;
+        if (udpTrackerClient_->receiveReply(req, data.data(), length,
+                                            remoteAddr, remotePort,
+                                            global::wallclock()) == 0) {
+          if (req->action == UDPT_ACT_ANNOUNCE) {
+            auto c = static_cast<TrackerWatcherCommand*>(req->user_data);
+            if (c) {
+              c->setStatus(Command::STATUS_ONESHOT_REALTIME);
+              e_->setNoWait(true);
+            }
+          }
+        }
       }
     }
   }
@@ -150,7 +164,7 @@ bool DHTInteractionCommand::execute()
       udpTrackerClient_->requestFail(UDPT_ERR_NETWORK);
     }
   }
-  e_->addCommand(std::unique_ptr<Command>(this));
+  e_->addRoutineCommand(std::unique_ptr<Command>(this));
   return false;
 }
 

src/DHTSetup.cc

@@ -80,14 +80,16 @@ DHTSetup::DHTSetup() {}
 
 DHTSetup::~DHTSetup() {}
 
-std::vector<std::unique_ptr<Command>> DHTSetup::setup(DownloadEngine* e,
-                                                      int family)
+std::pair<std::vector<std::unique_ptr<Command>>,
+          std::vector<std::unique_ptr<Command>>>
+DHTSetup::setup(DownloadEngine* e, int family)
 {
   std::vector<std::unique_ptr<Command>> tempCommands;
+  std::vector<std::unique_ptr<Command>> tempRoutineCommands;
   if ((family != AF_INET && family != AF_INET6) ||
       (family == AF_INET && DHTRegistry::isInitialized()) ||
       (family == AF_INET6 && DHTRegistry::isInitialized6())) {
-    return tempCommands;
+    return {};
   }
   try {
     // load routing table and localnode id here
@@ -212,7 +214,7 @@ std::vector<std::unique_ptr<Command>> DHTSetup::setup(DownloadEngine* e,
       command->setReadCheckSocket(connection->getSocket());
       command->setConnection(std::move(connection));
       command->setUDPTrackerClient(udpTrackerClient);
-      tempCommands.push_back(std::move(command));
+      tempRoutineCommands.push_back(std::move(command));
     }
     {
       auto command = make_unique<DHTTokenUpdateCommand>(
@@ -290,6 +292,7 @@ std::vector<std::unique_ptr<Command>> DHTSetup::setup(DownloadEngine* e,
                         " DHT is disabled."),
                     ex);
     tempCommands.clear();
+    tempRoutineCommands.clear();
     if (family == AF_INET) {
       DHTRegistry::clearData();
       e->getBtRegistry()->setUDPTrackerClient(
@@ -299,7 +302,8 @@ std::vector<std::unique_ptr<Command>> DHTSetup::setup(DownloadEngine* e,
       DHTRegistry::clearData6();
     }
   }
-  return tempCommands;
+  return std::make_pair(std::move(tempCommands),
+                        std::move(tempRoutineCommands));
 }
 
 } // namespace aria2

src/DHTSetup.h

@@ -51,7 +51,12 @@ public:
 
   ~DHTSetup();
 
-  std::vector<std::unique_ptr<Command>> setup(DownloadEngine* e, int family);
+  // Returns two vector of Commands.  First one contains regular
+  // commands.  Secod one contains so called routine commands, which
+  // executed once per event poll returns.
+  std::pair<std::vector<std::unique_ptr<Command>>,
+            std::vector<std::unique_ptr<Command>>>
+  setup(DownloadEngine* e, int family);
 };
 
 } // namespace aria2

src/RequestGroup.cc

@@ -349,12 +349,24 @@ void RequestGroup::createInitialCommand(
          option_->getAsBool(PREF_ENABLE_DHT6))) {
 
       if (option_->getAsBool(PREF_ENABLE_DHT)) {
-        e->addCommand(DHTSetup().setup(e, AF_INET));
+        std::vector<std::unique_ptr<Command>> c, rc;
+        std::tie(c, rc) = DHTSetup().setup(e, AF_INET);
+
+        e->addCommand(std::move(c));
+        for (auto& a : rc) {
+          e->addRoutineCommand(std::move(a));
+        }
       }
 
       if (!e->getOption()->getAsBool(PREF_DISABLE_IPV6) &&
           option_->getAsBool(PREF_ENABLE_DHT6)) {
-        e->addCommand(DHTSetup().setup(e, AF_INET6));
+        std::vector<std::unique_ptr<Command>> c, rc;
+        std::tie(c, rc) = DHTSetup().setup(e, AF_INET6);
+
+        e->addCommand(std::move(c));
+        for (auto& a : rc) {
+          e->addRoutineCommand(std::move(a));
+        }
       }
       const auto& nodes = torrentAttrs->nodes;
       // TODO Are nodes in torrent IPv4 only?

src/TrackerWatcherCommand.cc

@@ -229,6 +229,7 @@ bool TrackerWatcherCommand::execute()
     trackerRequest_ = createAnnounce(e_);
     if (trackerRequest_) {
       trackerRequest_->issue(e_);
+      A2_LOG_DEBUG("tracker request created");
     }
   }
   else if (trackerRequest_->stopped()) {
@@ -259,6 +260,12 @@ bool TrackerWatcherCommand::execute()
       }
     }
   }
+
+  if (!trackerRequest_ && btAnnounce_->noMoreAnnounce()) {
+    A2_LOG_DEBUG("no more announce");
+    return true;
+  }
+
   e_->addCommand(std::unique_ptr<Command>(this));
   return false;
 }
@@ -325,8 +332,10 @@ std::unique_ptr<AnnRequest>
 TrackerWatcherCommand::createUDPAnnRequest(const std::string& host,
                                            uint16_t port, uint16_t localPort)
 {
-  return make_unique<UDPAnnRequest>(
-      btAnnounce_->createUDPTrackerRequest(host, port, localPort));
+  auto req = btAnnounce_->createUDPTrackerRequest(host, port, localPort);
+  req->user_data = this;
+
+  return make_unique<UDPAnnRequest>(std::move(req));
 }
 
 namespace {

src/UDPTrackerClient.cc

@@ -132,7 +132,8 @@ struct CollectAddrPortMatch {
 };
 } // namespace
 
-int UDPTrackerClient::receiveReply(const unsigned char* data, size_t length,
+int UDPTrackerClient::receiveReply(std::shared_ptr<UDPTrackerRequest>& recvReq,
+                                   const unsigned char* data, size_t length,
                                    const std::string& remoteAddr,
                                    uint16_t remotePort, const Timer& now)
 {
@@ -167,6 +168,9 @@ int UDPTrackerClient::receiveReply(const unsigned char* data, size_t length,
                        CollectAddrPortMatch(reqs, remoteAddr, remotePort)),
         connectRequests_.end());
     pendingRequests_.insert(pendingRequests_.begin(), reqs.begin(), reqs.end());
+
+    recvReq = std::move(req);
+
     break;
   }
   case UDPT_ACT_ANNOUNCE: {
@@ -209,6 +213,9 @@ int UDPTrackerClient::receiveReply(const unsigned char* data, size_t length,
             getUDPTrackerEventStr(req->event),
             util::toHex(req->infohash).c_str(), req->reply->interval,
             req->reply->leechers, req->reply->seeders, numPeers));
+
+    recvReq = std::move(req);
+
     break;
   }
   case UDPT_ACT_ERROR: {
@@ -236,6 +243,9 @@ int UDPTrackerClient::receiveReply(const unsigned char* data, size_t length,
     if (req->action == UDPT_ACT_CONNECT) {
       failConnect(req->remoteAddr, req->remotePort, UDPT_ERR_TRACKER);
     }
+
+    recvReq = std::move(req);
+
     break;
   }
   case UDPT_ACT_SCRAPE:

src/UDPTrackerClient.h

@@ -74,7 +74,8 @@ public:
   UDPTrackerClient();
   ~UDPTrackerClient();
 
-  int receiveReply(const unsigned char* data, size_t length,
+  int receiveReply(std::shared_ptr<UDPTrackerRequest>& req,
+                   const unsigned char* data, size_t length,
                    const std::string& remoteAddr, uint16_t remotePort,
                    const Timer& now);
 

src/UDPTrackerRequest.cc

@@ -58,7 +58,8 @@ UDPTrackerRequest::UDPTrackerRequest()
       state(UDPT_STA_PENDING),
       error(UDPT_ERR_SUCCESS),
       dispatched(Timer::zero()),
-      failCount(0)
+      failCount(0),
+      user_data(nullptr)
 {
 }
 

src/UDPTrackerRequest.h

@@ -101,6 +101,7 @@ struct UDPTrackerRequest {
   Timer dispatched;
   int failCount;
   std::shared_ptr<UDPTrackerReply> reply;
+  void *user_data;
   UDPTrackerRequest();
 };
 

test/UDPTrackerClientTest.cc

@@ -156,6 +156,7 @@ void UDPTrackerClientTest::testConnectFollowedByAnnounce()
   std::string remoteAddr;
   uint16_t remotePort;
   Timer now;
+  std::shared_ptr<UDPTrackerRequest> recvReq;
 
   std::shared_ptr<UDPTrackerRequest> req1(
       createAnnounce("192.168.0.1", 6991, 0));
@@ -190,8 +191,12 @@ void UDPTrackerClientTest::testConnectFollowedByAnnounce()
 
   uint64_t connectionId = 12345;
   rv = createConnectReply(data, sizeof(data), connectionId, transactionId);
-  rv = tr.receiveReply(data, rv, req1->remoteAddr, req1->remotePort, now);
+  rv = tr.receiveReply(recvReq, data, rv, req1->remoteAddr, req1->remotePort,
+                       now);
   CPPUNIT_ASSERT_EQUAL(0, (int)rv);
+  if (rv == 0) {
+    CPPUNIT_ASSERT_EQUAL((int32_t)UDPT_ACT_CONNECT, recvReq->action);
+  }
   // Now 2 requests get back to pending
   CPPUNIT_ASSERT_EQUAL((size_t)2, tr.getPendingRequests().size());
 
@@ -229,15 +234,23 @@ void UDPTrackerClientTest::testConnectFollowedByAnnounce()
 
   // Reply for req2
   rv = createAnnounceReply(data, sizeof(data), transactionId2);
-  rv = tr.receiveReply(data, rv, req2->remoteAddr, req2->remotePort, now);
+  rv = tr.receiveReply(recvReq, data, rv, req2->remoteAddr, req2->remotePort,
+                       now);
   CPPUNIT_ASSERT_EQUAL(0, (int)rv);
+  if (rv == 0) {
+    CPPUNIT_ASSERT_EQUAL((int32_t)UDPT_ACT_ANNOUNCE, recvReq->action);
+  }
   CPPUNIT_ASSERT_EQUAL((int)UDPT_STA_COMPLETE, req2->state);
   CPPUNIT_ASSERT_EQUAL((int)UDPT_ERR_SUCCESS, req2->error);
 
   // Reply for req1
   rv = createAnnounceReply(data, sizeof(data), transactionId1, 2);
-  rv = tr.receiveReply(data, rv, req1->remoteAddr, req1->remotePort, now);
+  rv = tr.receiveReply(recvReq, data, rv, req1->remoteAddr, req1->remotePort,
+                       now);
   CPPUNIT_ASSERT_EQUAL(0, (int)rv);
+  if (rv == 0) {
+    CPPUNIT_ASSERT_EQUAL((int32_t)UDPT_ACT_ANNOUNCE, recvReq->action);
+  }
   CPPUNIT_ASSERT_EQUAL((int)UDPT_STA_COMPLETE, req1->state);
   CPPUNIT_ASSERT_EQUAL((int)UDPT_ERR_SUCCESS, req1->error);
   CPPUNIT_ASSERT_EQUAL((size_t)2, req1->reply->peers.size());
@@ -280,6 +293,8 @@ void UDPTrackerClientTest::testRequestFailure()
   std::string remoteAddr;
   uint16_t remotePort;
   Timer now;
+  std::shared_ptr<UDPTrackerRequest> recvReq;
+
   {
     std::shared_ptr<UDPTrackerRequest> req1(
         createAnnounce("192.168.0.1", 6991, 0));
@@ -315,7 +330,12 @@ void UDPTrackerClientTest::testRequestFailure()
     tr.requestSent(now);
 
     rv = createErrorReply(data, sizeof(data), transactionId, "error");
-    rv = tr.receiveReply(data, rv, req1->remoteAddr, req1->remotePort, now);
+    rv = tr.receiveReply(recvReq, data, rv, req1->remoteAddr, req1->remotePort,
+                         now);
+    CPPUNIT_ASSERT_EQUAL((ssize_t)0, rv);
+    if (rv == 0) {
+      CPPUNIT_ASSERT_EQUAL((int32_t)UDPT_ACT_CONNECT, recvReq->action);
+    }
     CPPUNIT_ASSERT_EQUAL((int)UDPT_STA_COMPLETE, req1->state);
     CPPUNIT_ASSERT_EQUAL((int)UDPT_ERR_TRACKER, req1->error);
     CPPUNIT_ASSERT_EQUAL((int)UDPT_STA_COMPLETE, req2->state);
@@ -338,7 +358,8 @@ void UDPTrackerClientTest::testRequestFailure()
 
     uint64_t connectionId = 12345;
     rv = createConnectReply(data, sizeof(data), connectionId, transactionId);
-    rv = tr.receiveReply(data, rv, req1->remoteAddr, req1->remotePort, now);
+    rv = tr.receiveReply(recvReq, data, rv, req1->remoteAddr, req1->remotePort,
+                         now);
     CPPUNIT_ASSERT_EQUAL(0, (int)rv);
 
     rv = tr.createRequest(data, sizeof(data), remoteAddr, remotePort, now);
@@ -348,7 +369,8 @@ void UDPTrackerClientTest::testRequestFailure()
     tr.requestSent(now);
 
     rv = createErrorReply(data, sizeof(data), transactionId, "announce error");
-    rv = tr.receiveReply(data, rv, req1->remoteAddr, req1->remotePort, now);
+    rv = tr.receiveReply(recvReq, data, rv, req1->remoteAddr, req1->remotePort,
+                         now);
     CPPUNIT_ASSERT_EQUAL((int)UDPT_STA_COMPLETE, req1->state);
     CPPUNIT_ASSERT_EQUAL((int)UDPT_ERR_TRACKER, req1->error);
     CPPUNIT_ASSERT(tr.getConnectRequests().empty());
@@ -365,6 +387,8 @@ void UDPTrackerClientTest::testTimeout()
   uint16_t remotePort;
   Timer now;
   UDPTrackerClient tr;
+  std::shared_ptr<UDPTrackerRequest> recvReq;
+
   {
     std::shared_ptr<UDPTrackerRequest> req1(
         createAnnounce("192.168.0.1", 6991, 0));
@@ -414,7 +438,8 @@ void UDPTrackerClientTest::testTimeout()
 
     uint64_t connectionId = 12345;
     rv = createConnectReply(data, sizeof(data), connectionId, transactionId);
-    rv = tr.receiveReply(data, rv, req1->remoteAddr, req1->remotePort, now);
+    rv = tr.receiveReply(recvReq, data, rv, req1->remoteAddr, req1->remotePort,
+                         now);
     CPPUNIT_ASSERT_EQUAL(0, (int)rv);
 
     rv = tr.createRequest(data, sizeof(data), remoteAddr, remotePort, now);