diff --git a/ChangeLog b/ChangeLog
index d0fcf446..f756a2ed 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2010-04-11  Tatsuhiro Tsujikawa  <t-tujikawa@users.sourceforge.net>
+
+	Use clock_gettime(CLOCK_MONOTONIC, ...) if it is available and
+	usable to prevent from aria2 from being affected by system time
+	change.
+
 2010-04-09  Tatsuhiro Tsujikawa  <t-tujikawa@users.sourceforge.net>
 
 	Added aria2.pause and aria2.unpause XML-RPC method.  aria2.pause
diff --git a/config.h.in b/config.h.in
index dbbd2b62..c248efbe 100644
--- a/config.h.in
+++ b/config.h.in
@@ -81,6 +81,9 @@
    the CoreFoundation framework. */
 #undef HAVE_CFPREFERENCESCOPYAPPVALUE
 
+/* Define to 1 if you have the `clock_gettime' function. */
+#undef HAVE_CLOCK_GETTIME
+
 /* Define to 1 if you have the `daemon' function. */
 #undef HAVE_DAEMON
 
@@ -418,6 +421,9 @@
 /* Define to 1 if you have the `strtoull' function. */
 #undef HAVE_STRTOULL
 
+/* Define to 1 if the system has the type `struct timespec'. */
+#undef HAVE_STRUCT_TIMESPEC
+
 /* Define to 1 if you have the <sys/ioctl.h> header file. */
 #undef HAVE_SYS_IOCTL_H
 
diff --git a/configure b/configure
index 0210dc8c..e5aa36ef 100755
--- a/configure
+++ b/configure
@@ -7431,6 +7431,63 @@ else
 fi
 
 
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for library containing clock_gettime" >&5
+$as_echo_n "checking for library containing clock_gettime... " >&6; }
+if test "${ac_cv_search_clock_gettime+set}" = set; then :
+  $as_echo_n "(cached) " >&6
+else
+  ac_func_search_save_LIBS=$LIBS
+cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+/* Override any GCC internal prototype to avoid an error.
+   Use char because int might match the return type of a GCC
+   builtin and then its argument prototype would still apply.  */
+#ifdef __cplusplus
+extern "C"
+#endif
+char clock_gettime ();
+int
+main ()
+{
+return clock_gettime ();
+  ;
+  return 0;
+}
+_ACEOF
+for ac_lib in '' rt; do
+  if test -z "$ac_lib"; then
+    ac_res="none required"
+  else
+    ac_res=-l$ac_lib
+    LIBS="-l$ac_lib  $ac_func_search_save_LIBS"
+  fi
+  if ac_fn_cxx_try_link "$LINENO"; then :
+  ac_cv_search_clock_gettime=$ac_res
+fi
+rm -f core conftest.err conftest.$ac_objext \
+    conftest$ac_exeext
+  if test "${ac_cv_search_clock_gettime+set}" = set; then :
+  break
+fi
+done
+if test "${ac_cv_search_clock_gettime+set}" = set; then :
+
+else
+  ac_cv_search_clock_gettime=no
+fi
+rm conftest.$ac_ext
+LIBS=$ac_func_search_save_LIBS
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_search_clock_gettime" >&5
+$as_echo "$ac_cv_search_clock_gettime" >&6; }
+ac_res=$ac_cv_search_clock_gettime
+if test "$ac_res" != no; then :
+  test "$ac_res" = "none required" || LIBS="$ac_res $LIBS"
+
+fi
+
+
 # Checks for header files.
 # The Ultrix 4.2 mips builtin alloca declared by alloca.h only works
 # for constant arguments.  Useless!
@@ -8295,6 +8352,15 @@ cat >>confdefs.h <<_ACEOF
 _ACEOF
 
 
+fi
+ac_fn_cxx_check_type "$LINENO" "struct timespec" "ac_cv_type_struct_timespec" "$ac_includes_default"
+if test "x$ac_cv_type_struct_timespec" = x""yes; then :
+
+cat >>confdefs.h <<_ACEOF
+#define HAVE_STRUCT_TIMESPEC 1
+_ACEOF
+
+
 fi
 
  { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether byte ordering is bigendian" >&5
@@ -14496,6 +14562,7 @@ for ac_func in __argz_count \
                 __argz_next \
                 __argz_stringify \
                 atexit \
+		clock_gettime \
                 ftruncate \
                 getcwd \
                 gethostbyaddr \
diff --git a/configure.ac b/configure.ac
index e2d3524f..f1ea59fc 100644
--- a/configure.ac
+++ b/configure.ac
@@ -208,6 +208,8 @@ AM_CONDITIONAL([HAVE_LIBZ], [test "x$have_libz" = "xyes"])
 # Set conditional for sqlite3
 AM_CONDITIONAL([HAVE_SQLITE3], [test "x$have_sqlite3" = "xyes"])
 
+AC_SEARCH_LIBS([clock_gettime], [rt])
+
 # Checks for header files.
 AC_FUNC_ALLOCA
 AC_HEADER_STDC
@@ -268,7 +270,7 @@ AC_TYPE_UINT64_T
 AC_TYPE_UINT8_T
 AC_TYPE_PID_T
 AC_C_VOLATILE
-AC_CHECK_TYPES([ptrdiff_t])
+AC_CHECK_TYPES([ptrdiff_t, struct timespec])
 AC_C_BIGENDIAN
 AC_SYS_LARGEFILE
 
@@ -291,6 +293,7 @@ AC_CHECK_FUNCS([__argz_count \
                 __argz_next \
                 __argz_stringify \
                 atexit \
+		clock_gettime \
                 ftruncate \
                 getcwd \
                 gethostbyaddr \
diff --git a/src/AbstractCommand.cc b/src/AbstractCommand.cc
index abe36b8b..5c84bbd9 100644
--- a/src/AbstractCommand.cc
+++ b/src/AbstractCommand.cc
@@ -75,7 +75,7 @@ AbstractCommand::AbstractCommand(cuid_t cuid,
                                  RequestGroup* requestGroup,
                                  DownloadEngine* e,
                                  const SocketHandle& s):
-  Command(cuid), _requestGroup(requestGroup),
+  Command(cuid), checkPoint(global::wallclock), _requestGroup(requestGroup),
   req(req), _fileEntry(fileEntry), e(e), socket(s),
   checkSocketIsReadable(false), checkSocketIsWritable(false),
   nameResolverCheck(false)
diff --git a/src/AbstractCommand.h b/src/AbstractCommand.h
index 8e7e6e98..fc793cee 100644
--- a/src/AbstractCommand.h
+++ b/src/AbstractCommand.h
@@ -37,7 +37,7 @@
 
 #include "Command.h"
 #include "SharedHandle.h"
-#include "TimeA2.h"
+#include "TimerA2.h"
 #include "FileEntry.h"
 #include "RequestGroup.h"
 
@@ -55,7 +55,7 @@ class AsyncNameResolver;
 
 class AbstractCommand : public Command {
 private:
-  Time checkPoint;
+  Timer checkPoint;
   time_t timeout;
 protected:
   RequestGroup* _requestGroup;
diff --git a/src/ActivePeerConnectionCommand.h b/src/ActivePeerConnectionCommand.h
index ff58b6ba..e4d081e4 100644
--- a/src/ActivePeerConnectionCommand.h
+++ b/src/ActivePeerConnectionCommand.h
@@ -37,7 +37,7 @@
 
 #include "Command.h"
 #include "SharedHandle.h"
-#include "TimeA2.h"
+#include "TimerA2.h"
 
 namespace aria2 {
 
@@ -59,7 +59,7 @@ private:
 
   time_t interval; // UNIT: sec
   DownloadEngine* e;
-  Time checkPoint;
+  Timer checkPoint;
   unsigned int _numNewConnection; // the number of the connection to establish.
 public:
   ActivePeerConnectionCommand(cuid_t cuid,
diff --git a/src/AdaptiveURISelector.cc b/src/AdaptiveURISelector.cc
index f1537429..fb0c83e6 100644
--- a/src/AdaptiveURISelector.cc
+++ b/src/AdaptiveURISelector.cc
@@ -51,7 +51,6 @@
 #include "SimpleRandomizer.h"
 #include "SocketCore.h"
 #include "FileEntry.h"
-#include "wallclock.h"
 
 namespace aria2 {
 
@@ -330,7 +329,7 @@ std::string AdaptiveURISelector::getFirstToTestUri
     power = (int)pow(2.0, (float)counter);
     /* We test the mirror another time if it has not been
      * tested since 2^counter days */
-    if(ss->getLastUpdated().difference(global::wallclock) > power*24*60*60) {
+    if(ss->getLastUpdated().difference() > power*24*60*60) {
       return *i;
     }
   }
diff --git a/src/BtLeecherStateChoke.cc b/src/BtLeecherStateChoke.cc
index 7fd6ca8c..266e5723 100644
--- a/src/BtLeecherStateChoke.cc
+++ b/src/BtLeecherStateChoke.cc
@@ -39,7 +39,6 @@
 #include "Peer.h"
 #include "Logger.h"
 #include "LogFactory.h"
-#include "a2time.h"
 #include "SimpleRandomizer.h"
 #include "wallclock.h"
 
@@ -216,7 +215,7 @@ BtLeecherStateChoke::executeChoke
   }
 }
 
-const Time& BtLeecherStateChoke::getLastRound() const
+const Timer& BtLeecherStateChoke::getLastRound() const
 {
   return _lastRound;
 }
diff --git a/src/BtLeecherStateChoke.h b/src/BtLeecherStateChoke.h
index 062342d1..89914bec 100644
--- a/src/BtLeecherStateChoke.h
+++ b/src/BtLeecherStateChoke.h
@@ -40,7 +40,7 @@
 #include <vector>
 
 #include "SharedHandle.h"
-#include "TimeA2.h"
+#include "TimerA2.h"
 
 namespace aria2 {
 
@@ -51,7 +51,7 @@ class BtLeecherStateChoke {
 private:
   int _round;
 
-  Time _lastRound;
+  Timer _lastRound;
 
   Logger* _logger;
 
@@ -95,7 +95,7 @@ public:
 
   void executeChoke(const std::vector<SharedHandle<Peer> >& peerSet);
 
-  const Time& getLastRound() const;
+  const Timer& getLastRound() const;
 };
 
 } // namespace aria2
diff --git a/src/BtSeederStateChoke.cc b/src/BtSeederStateChoke.cc
index 4d12fd37..48f28dfc 100644
--- a/src/BtSeederStateChoke.cc
+++ b/src/BtSeederStateChoke.cc
@@ -69,7 +69,7 @@ BtSeederStateChoke::PeerEntry::operator<(const PeerEntry& rhs) const
     return false;
   }
   if(this->_recentUnchoking &&
-     this->_lastAmUnchoking.isNewer(rhs._lastAmUnchoking)) {
+     (this->_lastAmUnchoking > rhs._lastAmUnchoking)) {
     return true;
   } else if(rhs._recentUnchoking) {
     return false;
diff --git a/src/BtSeederStateChoke.h b/src/BtSeederStateChoke.h
index eec74728..932bc3f5 100644
--- a/src/BtSeederStateChoke.h
+++ b/src/BtSeederStateChoke.h
@@ -40,7 +40,7 @@
 #include <vector>
 
 #include "SharedHandle.h"
-#include "TimeA2.h"
+#include "TimerA2.h"
 
 namespace aria2 {
 
@@ -51,7 +51,7 @@ class BtSeederStateChoke {
 private:
   int _round;
 
-  Time _lastRound;
+  Timer _lastRound;
 
   Logger* _logger;
 
@@ -59,7 +59,7 @@ private:
   private:
     SharedHandle<Peer> _peer;
     size_t _outstandingUpload;
-    Time _lastAmUnchoking;
+    Timer _lastAmUnchoking;
     bool _recentUnchoking;
     unsigned int _uploadSpeed;
     
@@ -87,7 +87,7 @@ public:
 
   void executeChoke(const std::vector<SharedHandle<Peer> >& peerSet);
 
-  const Time& getLastRound() const { return _lastRound; }
+  const Timer& getLastRound() const { return _lastRound; }
 };
 
 } // namespace aria2
diff --git a/src/BtStopDownloadCommand.h b/src/BtStopDownloadCommand.h
index 193b5439..715ccbcc 100644
--- a/src/BtStopDownloadCommand.h
+++ b/src/BtStopDownloadCommand.h
@@ -52,7 +52,7 @@ private:
   
   time_t _timeout;
 
-  Time _checkPoint;
+  Timer _checkPoint;
 
   SharedHandle<BtRuntime> _btRuntime;
 
diff --git a/src/CheckIntegrityCommand.h b/src/CheckIntegrityCommand.h
index b950a43b..7f48c725 100644
--- a/src/CheckIntegrityCommand.h
+++ b/src/CheckIntegrityCommand.h
@@ -37,7 +37,6 @@
 
 #include "RealtimeCommand.h"
 #include "SharedHandle.h"
-#include "TimeA2.h"
 
 namespace aria2 {
 
@@ -46,7 +45,6 @@ class CheckIntegrityEntry;
 class CheckIntegrityCommand : public RealtimeCommand {
 private:
   SharedHandle<CheckIntegrityEntry> _entry;
-  Time _timer;
 public:
   CheckIntegrityCommand(cuid_t cuid,
                         RequestGroup* requestGroup,
diff --git a/src/ConsoleStatCalc.h b/src/ConsoleStatCalc.h
index 0501c3c0..62db9fe2 100644
--- a/src/ConsoleStatCalc.h
+++ b/src/ConsoleStatCalc.h
@@ -36,7 +36,7 @@
 #define _D_CONSOLE_STAT_CALC_H_
 
 #include "StatCalc.h"
-#include "TimeA2.h"
+#include "TimerA2.h"
 #include "util.h"
 
 namespace aria2 {
@@ -72,9 +72,9 @@ protected:
 class ConsoleStatCalc:public StatCalc
 {
 private:
-  Time _cp;
+  Timer _cp;
 
-  Time _lastSummaryNotified;
+  Timer _lastSummaryNotified;
 
   time_t _summaryInterval;
 
diff --git a/src/DHTBucket.h b/src/DHTBucket.h
index 4b036862..4b55d490 100644
--- a/src/DHTBucket.h
+++ b/src/DHTBucket.h
@@ -43,7 +43,7 @@
 
 #include "SharedHandle.h"
 #include "DHTConstants.h"
-#include "TimeA2.h"
+#include "TimerA2.h"
 
 namespace aria2 {
 
@@ -68,7 +68,7 @@ private:
   // This is sorted by last time seen.
   std::deque<SharedHandle<DHTNode> > _cachedNodes;
 
-  Time _lastUpdated;
+  Timer _lastUpdated;
 
   Logger* _logger;
 
diff --git a/src/DHTGetPeersCommand.h b/src/DHTGetPeersCommand.h
index 7fbd7483..753dfda5 100644
--- a/src/DHTGetPeersCommand.h
+++ b/src/DHTGetPeersCommand.h
@@ -37,7 +37,7 @@
 
 #include "Command.h"
 #include "SharedHandle.h"
-#include "TimeA2.h"
+#include "TimerA2.h"
 
 namespace aria2 {
 
@@ -72,7 +72,7 @@ private:
 
   size_t _numRetry;
 
-  Time _lastGetPeerTime;
+  Timer _lastGetPeerTime;
 public:
   DHTGetPeersCommand(cuid_t cuid, RequestGroup* requestGroup,
                      DownloadEngine* e);
diff --git a/src/DHTMessageTrackerEntry.h b/src/DHTMessageTrackerEntry.h
index bdc2f8f0..1cf979be 100644
--- a/src/DHTMessageTrackerEntry.h
+++ b/src/DHTMessageTrackerEntry.h
@@ -38,7 +38,7 @@
 #include "common.h"
 #include "SharedHandle.h"
 #include "DHTConstants.h"
-#include "TimeA2.h"
+#include "TimerA2.h"
 #include <string>
 
 namespace aria2 {
@@ -57,7 +57,7 @@ private:
   
   SharedHandle<DHTMessageCallback> _callback;
 
-  Time _dispatchedTime;
+  Timer _dispatchedTime;
 
   time_t _timeout;
 public:
diff --git a/src/DHTNode.h b/src/DHTNode.h
index ed2f21e3..aa78f409 100644
--- a/src/DHTNode.h
+++ b/src/DHTNode.h
@@ -38,7 +38,7 @@
 #include "common.h"
 #include "SharedHandle.h"
 #include "DHTConstants.h"
-#include "TimeA2.h"
+#include "TimerA2.h"
 #include <string>
 
 namespace aria2 {
@@ -56,7 +56,7 @@ private:
 
   unsigned int _condition;
 
-  Time _lastContact;
+  Timer _lastContact;
 public:
   DHTNode();
   
diff --git a/src/DHTPeerAnnounceEntry.h b/src/DHTPeerAnnounceEntry.h
index f957ba59..0bd8e318 100644
--- a/src/DHTPeerAnnounceEntry.h
+++ b/src/DHTPeerAnnounceEntry.h
@@ -42,7 +42,7 @@
 #include "SharedHandle.h"
 #include "DHTConstants.h"
 #include "PeerAddrEntry.h"
-#include "TimeA2.h"
+#include "TimerA2.h"
 
 namespace aria2 {
 
@@ -54,7 +54,7 @@ private:
 
   std::vector<PeerAddrEntry> _peerAddrEntries;
 
-  Time _lastUpdated;
+  Timer _lastUpdated;
 public:
   DHTPeerAnnounceEntry(const unsigned char* infoHash);
 
@@ -75,7 +75,7 @@ public:
   
   bool empty() const;
 
-  const Time& getLastUpdated() const
+  const Timer& getLastUpdated() const
   {
     return _lastUpdated;
   }
diff --git a/src/DHTRoutingTableSerializer.cc b/src/DHTRoutingTableSerializer.cc
index dfdee303..8af78793 100644
--- a/src/DHTRoutingTableSerializer.cc
+++ b/src/DHTRoutingTableSerializer.cc
@@ -46,6 +46,7 @@
 #include "a2netcompat.h"
 #include "StringFormat.h"
 #include "util.h"
+#include "TimeA2.h"
 
 namespace aria2 {
 
diff --git a/src/DHTSetup.cc b/src/DHTSetup.cc
index f5df82c2..bf64a5dc 100644
--- a/src/DHTSetup.cc
+++ b/src/DHTSetup.cc
@@ -192,7 +192,7 @@ void DHTSetup::setup(std::vector<Command*>& commands, DownloadEngine* e)
     }
     if(!desnodes.empty() &&
        deserializer.getSerializedTime().
-       difference(global::wallclock) >= DHT_BUCKET_REFRESH_INTERVAL) {
+       difference() >= DHT_BUCKET_REFRESH_INTERVAL) {
       SharedHandle<DHTBucketRefreshTask> task
         (dynamic_pointer_cast<DHTBucketRefreshTask>(taskFactory->createBucketRefreshTask()));
       task->setForceRefresh(true);
diff --git a/src/DefaultBtAnnounce.cc b/src/DefaultBtAnnounce.cc
index cfecf3a2..09e7013b 100644
--- a/src/DefaultBtAnnounce.cc
+++ b/src/DefaultBtAnnounce.cc
@@ -61,6 +61,7 @@ DefaultBtAnnounce::DefaultBtAnnounce
  const Option* option):
   _downloadContext(downloadContext),
   trackers(0),
+  prevAnnounceTimer(0),
   interval(DEFAULT_ANNOUNCE_INTERVAL),
   minInterval(DEFAULT_ANNOUNCE_INTERVAL),
   _userDefinedInterval(0),
@@ -70,9 +71,7 @@ DefaultBtAnnounce::DefaultBtAnnounce
   option(option),
   logger(LogFactory::getInstance()),
   _randomizer(SimpleRandomizer::getInstance())
-{
-  prevAnnounceTime.setTimeInSec(0);
-}
+{}
 
 DefaultBtAnnounce::~DefaultBtAnnounce() {
 }
@@ -80,7 +79,7 @@ DefaultBtAnnounce::~DefaultBtAnnounce() {
 bool DefaultBtAnnounce::isDefaultAnnounceReady() {
   return
     (trackers == 0 &&
-     prevAnnounceTime.
+     prevAnnounceTimer.
      difference(global::wallclock) >= (_userDefinedInterval==0?
                                        minInterval:_userDefinedInterval) &&
      !announceList.allTiersFailed());
@@ -207,7 +206,7 @@ bool DefaultBtAnnounce::isAllAnnounceFailed() {
 }
 
 void DefaultBtAnnounce::resetAnnounce() {
-  prevAnnounceTime = global::wallclock;
+  prevAnnounceTimer = global::wallclock;
   announceList.resetTier();
 }
 
diff --git a/src/DefaultBtAnnounce.h b/src/DefaultBtAnnounce.h
index 78ccd2ac..35b2b045 100644
--- a/src/DefaultBtAnnounce.h
+++ b/src/DefaultBtAnnounce.h
@@ -36,7 +36,7 @@
 #define _D_DEFAULT_BT_ANNOUNCE_H_
 
 #include "BtAnnounce.h"
-#include "TimeA2.h"
+#include "TimerA2.h"
 #include "AnnounceList.h"
 
 namespace aria2 {
@@ -53,7 +53,7 @@ class DefaultBtAnnounce : public BtAnnounce {
 private:
   SharedHandle<DownloadContext> _downloadContext;
   unsigned int trackers;
-  Time prevAnnounceTime;
+  Timer prevAnnounceTimer;
   time_t interval;
   time_t minInterval;
   time_t _userDefinedInterval;
diff --git a/src/DefaultBtInteractive.cc b/src/DefaultBtInteractive.cc
index c38c7b74..a17e6dca 100644
--- a/src/DefaultBtInteractive.cc
+++ b/src/DefaultBtInteractive.cc
@@ -163,11 +163,11 @@ BtMessageHandle DefaultBtInteractive::receiveAndSendHandshake() {
 }
 
 void DefaultBtInteractive::doPostHandshakeProcessing() {
-  // Set time 0 to haveCheckPoint to cache http/ftp download piece completion
-  haveCheckPoint.setTimeInSec(0);
-  keepAliveCheckPoint = global::wallclock;
-  floodingCheckPoint = global::wallclock;
-  _pexCheckPoint.setTimeInSec(0);
+  // Set time 0 to haveTimer to cache http/ftp download piece completion
+  haveTimer.reset(0);
+  keepAliveTimer = global::wallclock;
+  floodingTimer = global::wallclock;
+  _pexTimer.reset(0);
   if(peer->isExtendedMessagingEnabled()) {
     addHandshakeExtendedMessageToQueue();
   }
@@ -249,8 +249,8 @@ void DefaultBtInteractive::decideChoking() {
 
 void DefaultBtInteractive::checkHave() {
   std::vector<size_t> indexes;
-  _pieceStorage->getAdvertisedPieceIndexes(indexes, cuid, haveCheckPoint);
-  haveCheckPoint = global::wallclock;
+  _pieceStorage->getAdvertisedPieceIndexes(indexes, cuid, haveTimer);
+  haveTimer = global::wallclock;
   if(indexes.size() >= 20) {
     if(peer->isFastExtensionEnabled() && _pieceStorage->allDownloadFinished()) {
       dispatcher->addMessageToQueue(messageFactory->createHaveAllMessage());
@@ -266,10 +266,10 @@ void DefaultBtInteractive::checkHave() {
 }
 
 void DefaultBtInteractive::sendKeepAlive() {
-  if(keepAliveCheckPoint.difference(global::wallclock) >= keepAliveInterval) {
+  if(keepAliveTimer.difference(global::wallclock) >= keepAliveInterval) {
     dispatcher->addMessageToQueue(messageFactory->createKeepAliveMessage());
     dispatcher->sendMessages();
-    keepAliveCheckPoint = global::wallclock;
+    keepAliveTimer = global::wallclock;
   }
 }
 
@@ -311,7 +311,7 @@ size_t DefaultBtInteractive::receiveMessages() {
       _peerStorage->updateTransferStatFor(peer);
       // pass through
     case BtRequestMessage::ID:
-      inactiveCheckPoint = global::wallclock;
+      inactiveTimer = global::wallclock;
       break;
     }
   }
@@ -422,7 +422,7 @@ void DefaultBtInteractive::sendPendingMessage() {
 }
 
 void DefaultBtInteractive::detectMessageFlooding() {
-  if(floodingCheckPoint.
+  if(floodingTimer.
      difference(global::wallclock) >= FLOODING_CHECK_INTERVAL) {
     if(floodingStat.getChokeUnchokeCount() >= 2 ||
        floodingStat.getKeepAliveCount() >= 2) {
@@ -430,13 +430,13 @@ void DefaultBtInteractive::detectMessageFlooding() {
     } else {
       floodingStat.reset();
     }
-    floodingCheckPoint = global::wallclock;
+    floodingTimer = global::wallclock;
   }
 }
 
 void DefaultBtInteractive::checkActiveInteraction()
 {
-  time_t inactiveTime = inactiveCheckPoint.difference(global::wallclock);
+  time_t inactiveTime = inactiveTimer.difference(global::wallclock);
   // To allow aria2 to accept mutially interested peer, disconnect unintersted
   // peer.
   {
@@ -463,7 +463,7 @@ void DefaultBtInteractive::checkActiveInteraction()
 
 void DefaultBtInteractive::addPeerExchangeMessage()
 {
-  if(_pexCheckPoint.
+  if(_pexTimer.
      difference(global::wallclock) >= UTPexExtensionMessage::DEFAULT_INTERVAL) {
     UTPexExtensionMessageHandle m
       (new UTPexExtensionMessage(peer->getExtensionMessageID("ut_pex")));
@@ -489,7 +489,7 @@ void DefaultBtInteractive::addPeerExchangeMessage()
     }
     BtMessageHandle msg = messageFactory->createBtExtendedMessage(m);
     dispatcher->addMessageToQueue(msg);
-    _pexCheckPoint = global::wallclock;
+    _pexTimer = global::wallclock;
   }
 }
 
@@ -510,8 +510,8 @@ void DefaultBtInteractive::doInteractionProcessing() {
         _utMetadataRequestFactory->create(requests, num, _pieceStorage);
         dispatcher->addMessageToQueue(requests);
       }
-      if(_perSecCheckPoint.difference(global::wallclock) >= 1) {
-        _perSecCheckPoint = global::wallclock;
+      if(_perSecTimer.difference(global::wallclock) >= 1) {
+        _perSecTimer = global::wallclock;
         // Drop timeout request after queuing message to give a chance
         // to other connection to request piece.
         std::vector<size_t> indexes =
@@ -533,8 +533,8 @@ void DefaultBtInteractive::doInteractionProcessing() {
 
     detectMessageFlooding();
 
-    if(_perSecCheckPoint.difference(global::wallclock) >= 1) {
-      _perSecCheckPoint = global::wallclock;
+    if(_perSecTimer.difference(global::wallclock) >= 1) {
+      _perSecTimer = global::wallclock;
       dispatcher->checkRequestSlotAndDoNecessaryThing();
     }
     checkHave();
diff --git a/src/DefaultBtInteractive.h b/src/DefaultBtInteractive.h
index 5b72f12d..4ec1a85d 100644
--- a/src/DefaultBtInteractive.h
+++ b/src/DefaultBtInteractive.h
@@ -39,7 +39,7 @@
 
 #include  <limits.h>
 
-#include "TimeA2.h"
+#include "TimerA2.h"
 #include "Command.h"
 
 namespace aria2 {
@@ -126,13 +126,13 @@ private:
 
   Logger* logger;
   size_t allowedFastSetSize;
-  Time haveCheckPoint;
-  Time keepAliveCheckPoint;
-  Time floodingCheckPoint;
+  Timer haveTimer;
+  Timer keepAliveTimer;
+  Timer floodingTimer;
   FloodingStat floodingStat;
-  Time inactiveCheckPoint;
-  Time _pexCheckPoint;
-  Time _perSecCheckPoint;
+  Timer inactiveTimer;
+  Timer _pexTimer;
+  Timer _perSecTimer;
   time_t keepAliveInterval;
   bool _utPexEnabled;
   bool _dhtEnabled;
diff --git a/src/DefaultPeerStorage.cc b/src/DefaultPeerStorage.cc
index 5f9053b7..59e92abd 100644
--- a/src/DefaultPeerStorage.cc
+++ b/src/DefaultPeerStorage.cc
@@ -39,7 +39,6 @@
 #include "LogFactory.h"
 #include "Logger.h"
 #include "message.h"
-#include "a2time.h"
 #include "Peer.h"
 #include "BtRuntime.h"
 #include "BtSeederStateChoke.h"
diff --git a/src/DefaultPeerStorage.h b/src/DefaultPeerStorage.h
index 62bb6ad5..afb1c0fe 100644
--- a/src/DefaultPeerStorage.h
+++ b/src/DefaultPeerStorage.h
@@ -39,7 +39,7 @@
 
 #include <map>
 
-#include "TimeA2.h"
+#include "TimerA2.h"
 
 namespace aria2 {
 
@@ -65,7 +65,7 @@ private:
 
   std::map<std::string, TransferStat> _peerTransferStatMap;
 
-  Time _lastTransferStatMapUpdated;
+  Timer _lastTransferStatMapUpdated;
 
   TransferStat _cachedTransferStat;
 
diff --git a/src/DefaultPieceStorage.cc b/src/DefaultPieceStorage.cc
index dd963201..2807373a 100644
--- a/src/DefaultPieceStorage.cc
+++ b/src/DefaultPieceStorage.cc
@@ -537,14 +537,14 @@ size_t DefaultPieceStorage::getPieceLength(size_t index)
 
 void DefaultPieceStorage::advertisePiece(cuid_t cuid, size_t index)
 {
-  HaveEntry entry(cuid, index);
+  HaveEntry entry(cuid, index, global::wallclock);
   haves.push_front(entry);
 }
 
 void
 DefaultPieceStorage::getAdvertisedPieceIndexes(std::vector<size_t>& indexes,
                                                cuid_t myCuid,
-                                               const Time& lastCheckTime)
+                                               const Timer& lastCheckTime)
 {
   for(std::deque<HaveEntry>::const_iterator itr = haves.begin(),
         eoi = haves.end(); itr != eoi; ++itr) {
@@ -552,7 +552,7 @@ DefaultPieceStorage::getAdvertisedPieceIndexes(std::vector<size_t>& indexes,
     if(have.getCuid() == myCuid) {
       continue;
     }
-    if(lastCheckTime.isNewer(have.getRegisteredTime())) {
+    if(lastCheckTime > have.getRegisteredTime()) {
       break;
     }
     indexes.push_back(have.getIndex());
diff --git a/src/DefaultPieceStorage.h b/src/DefaultPieceStorage.h
index 9e6f06e8..01ed976d 100644
--- a/src/DefaultPieceStorage.h
+++ b/src/DefaultPieceStorage.h
@@ -56,17 +56,18 @@ class HaveEntry {
 private:
   cuid_t cuid;
   size_t index;
-  Time registeredTime;
+  Timer registeredTime;
 public:
-  HaveEntry(cuid_t cuid, size_t index):
+  HaveEntry(cuid_t cuid, size_t index, const Timer& registeredTime):
     cuid(cuid),
-    index(index) {}
+    index(index),
+    registeredTime(registeredTime) {}
 
   cuid_t getCuid() const { return cuid; }
 
   size_t getIndex() const { return index; }
 
-  const Time& getRegisteredTime() const { return registeredTime; }
+  const Timer& getRegisteredTime() const { return registeredTime; }
 };
 
 class DefaultPieceStorage : public PieceStorage {
@@ -195,7 +196,7 @@ public:
 
   virtual void
   getAdvertisedPieceIndexes(std::vector<size_t>& indexes,
-                            cuid_t myCuid, const Time& lastCheckTime);
+                            cuid_t myCuid, const Timer& lastCheckTime);
 
   virtual void removeAdvertisedPiece(time_t elapsed);
 
diff --git a/src/DownloadContext.cc b/src/DownloadContext.cc
index 130f3795..3261bf3a 100644
--- a/src/DownloadContext.cc
+++ b/src/DownloadContext.cc
@@ -69,7 +69,7 @@ DownloadContext::DownloadContext(size_t pieceLength,
 void DownloadContext::resetDownloadStartTime()
 {
   _downloadStartTime = global::wallclock;
-  _downloadStopTime.setTimeInSec(0);
+  _downloadStopTime.reset(0);
 }
 
 void DownloadContext::resetDownloadStopTime()
@@ -79,9 +79,9 @@ void DownloadContext::resetDownloadStopTime()
 
 int64_t DownloadContext::calculateSessionTime() const
 {
-  if(_downloadStopTime.isNewer(_downloadStartTime)) {
+  if(_downloadStopTime > _downloadStartTime) {
     return
-      _downloadStopTime.getTimeInMillis()-_downloadStartTime.getTimeInMillis();
+      _downloadStartTime.differenceInMillis(_downloadStopTime);
   } else {
     return 0;
   }
diff --git a/src/DownloadContext.h b/src/DownloadContext.h
index adbe534b..4daa0e37 100644
--- a/src/DownloadContext.h
+++ b/src/DownloadContext.h
@@ -43,7 +43,7 @@
 
 #include "SharedHandle.h"
 #include "Signature.h"
-#include "TimeA2.h"
+#include "TimerA2.h"
 #include "A2STR.h"
 #include "BDE.h"
 #include "IntSequence.h"
@@ -78,9 +78,9 @@ private:
   
   BDE _attrs;
 
-  Time _downloadStartTime;
+  Timer _downloadStartTime;
 
-  Time _downloadStopTime;
+  Timer _downloadStopTime;
 
   SharedHandle<Signature> _signature;
 
@@ -233,7 +233,7 @@ public:
 
   void resetDownloadStopTime();
 
-  const Time& getDownloadStopTime() const
+  const Timer& getDownloadStopTime() const
   {
     return _downloadStopTime;
   }
diff --git a/src/DownloadEngine.cc b/src/DownloadEngine.cc
index 2d3b0489..8f7d6b7d 100644
--- a/src/DownloadEngine.cc
+++ b/src/DownloadEngine.cc
@@ -48,8 +48,6 @@
 #include "StatCalc.h"
 #include "LogFactory.h"
 #include "Logger.h"
-#include "TimeA2.h"
-#include "a2time.h"
 #include "Socket.h"
 #include "util.h"
 #include "a2functional.h"
@@ -80,7 +78,7 @@ namespace global {
 
 // Global clock, this clock is reseted before executeCommand() call to
 // reduce the call gettimeofday() system call.
-Time wallclock;
+Timer wallclock;
 
 // 0 ... running
 // 1 ... stop signal detected
@@ -141,8 +139,8 @@ static void executeCommand(std::deque<Command*>& commands,
 
 void DownloadEngine::run()
 {
-  Time cp;
-  cp.setTimeInSec(0);
+  Timer cp;
+  cp.reset(0);
   while(!commands.empty() || !_routineCommands.empty()) {
     global::wallclock.reset();
     if(cp.difference(global::wallclock) >= _refreshInterval) {
diff --git a/src/DownloadEngine.h b/src/DownloadEngine.h
index fff1c5fd..b29adca5 100644
--- a/src/DownloadEngine.h
+++ b/src/DownloadEngine.h
@@ -44,7 +44,7 @@
 
 #include "SharedHandle.h"
 #include "a2netcompat.h"
-#include "TimeA2.h"
+#include "TimerA2.h"
 #include "a2io.h"
 #ifdef ENABLE_ASYNC_DNS
 # include "AsyncNameResolver.h"
@@ -92,7 +92,7 @@ private:
 
     time_t _timeout;
 
-    Time _registeredTime;
+    Timer _registeredTime;
   public:
     SocketPoolEntry(const SharedHandle<SocketCore>& socket,
                     const std::map<std::string, std::string>& option,
@@ -116,7 +116,7 @@ private:
   // key = IP address:port, value = SocketPoolEntry
   std::multimap<std::string, SocketPoolEntry> _socketPool;
  
-  Time _lastSocketPoolScan;
+  Timer _lastSocketPoolScan;
 
   bool _noWait;
 
diff --git a/src/DownloadEngineFactory.cc b/src/DownloadEngineFactory.cc
index d855f5af..e3f93646 100644
--- a/src/DownloadEngineFactory.cc
+++ b/src/DownloadEngineFactory.cc
@@ -107,7 +107,7 @@ DownloadEngineFactory::newDownloadEngine
 #ifdef ENABLE_MESSAGE_DIGEST
   e->_checkIntegrityMan.reset(new CheckIntegrityMan());
 #endif // ENABLE_MESSAGE_DIGEST
-  e->addRoutineCommand(new FillRequestGroupCommand(e->newCUID(), e.get(), 1));
+  e->addRoutineCommand(new FillRequestGroupCommand(e->newCUID(), e.get()));
   e->addRoutineCommand(new FileAllocationDispatcherCommand
                        (e->newCUID(), e->_fileAllocationMan, e.get()));
 #ifdef ENABLE_MESSAGE_DIGEST
diff --git a/src/EventPoll.h b/src/EventPoll.h
index 431badc1..807f8886 100644
--- a/src/EventPoll.h
+++ b/src/EventPoll.h
@@ -37,7 +37,7 @@
 
 #include "common.h"
 #include "SharedHandle.h"
-#include "TimeA2.h"
+#include "a2time.h"
 #include "a2netcompat.h"
 
 namespace aria2 {
diff --git a/src/FileAllocationCommand.cc b/src/FileAllocationCommand.cc
index aa1029b8..f3ca426a 100644
--- a/src/FileAllocationCommand.cc
+++ b/src/FileAllocationCommand.cc
@@ -45,6 +45,7 @@
 #include "DownloadContext.h"
 #include "a2functional.h"
 #include "RecoverableException.h"
+#include "wallclock.h"
 
 namespace aria2 {
 
@@ -65,7 +66,7 @@ bool FileAllocationCommand::executeInternal()
   if(_fileAllocationEntry->finished()) {
     if(logger->debug()) {
       logger->debug(MSG_ALLOCATION_COMPLETED,
-                    _timer.difference(),
+                    _timer.difference(global::wallclock),
                     util::itos(_requestGroup->getTotalLength(), true).c_str());
     }
     _e->_fileAllocationMan->dropPickedEntry();
diff --git a/src/FileAllocationCommand.h b/src/FileAllocationCommand.h
index 42177fa9..4aaecf73 100644
--- a/src/FileAllocationCommand.h
+++ b/src/FileAllocationCommand.h
@@ -37,7 +37,7 @@
 
 #include "RealtimeCommand.h"
 #include "SharedHandle.h"
-#include "TimeA2.h"
+#include "TimerA2.h"
 
 namespace aria2 {
 
@@ -46,7 +46,7 @@ class FileAllocationEntry;
 class FileAllocationCommand : public RealtimeCommand {
 private:
   SharedHandle<FileAllocationEntry> _fileAllocationEntry;
-  Time _timer;
+  Timer _timer;
 public:
   FileAllocationCommand(cuid_t cuid, RequestGroup* requestGroup,
                         DownloadEngine* e,
diff --git a/src/FillRequestGroupCommand.cc b/src/FillRequestGroupCommand.cc
index b8e74db0..3c8e0120 100644
--- a/src/FillRequestGroupCommand.cc
+++ b/src/FillRequestGroupCommand.cc
@@ -45,11 +45,9 @@
 namespace aria2 {
 
 FillRequestGroupCommand::FillRequestGroupCommand(cuid_t cuid,
-                                                 DownloadEngine* e,
-                                                 time_t interval):
+                                                 DownloadEngine* e):
   Command(cuid),
-  _e(e),
-  _interval(interval)
+  _e(e)
 {
   setStatusRealtime();
 }
diff --git a/src/FillRequestGroupCommand.h b/src/FillRequestGroupCommand.h
index e6ba46ee..55cb115b 100644
--- a/src/FillRequestGroupCommand.h
+++ b/src/FillRequestGroupCommand.h
@@ -37,7 +37,7 @@
 
 #include "Command.h"
 #include "SharedHandle.h"
-#include "TimeA2.h"
+#include "a2time.h"
 
 namespace aria2 {
 
@@ -47,19 +47,12 @@ class DownloadEngine;
 class FillRequestGroupCommand : public Command {
 private:
   DownloadEngine* _e;
-  time_t _interval;
-  Time _checkPoint;
 public:
-  FillRequestGroupCommand(cuid_t cuid, DownloadEngine* e, time_t interval);
+  FillRequestGroupCommand(cuid_t cuid, DownloadEngine* e);
 
   virtual ~FillRequestGroupCommand();
 
   virtual bool execute();
-
-  void setInterval(time_t interval)
-  {
-    _interval = interval;
-  }
 };
 
 } // namespace aria2
diff --git a/src/HttpServerBodyCommand.cc b/src/HttpServerBodyCommand.cc
index 5c15a2b3..1fdbfe67 100644
--- a/src/HttpServerBodyCommand.cc
+++ b/src/HttpServerBodyCommand.cc
@@ -81,7 +81,7 @@ bool HttpServerBodyCommand::execute()
   }
   try {
     if(_socket->isReadable(0) || _httpServer->getContentLength() == 0) {
-      _timeout = global::wallclock;
+      _timeoutTimer = global::wallclock;
 
       if(_httpServer->receiveBody()) {
         // Do something for requestpath and body
@@ -108,7 +108,7 @@ bool HttpServerBodyCommand::execute()
         return false;
       } 
     } else {
-      if(_timeout.difference(global::wallclock) >= 30) {
+      if(_timeoutTimer.difference(global::wallclock) >= 30) {
         logger->info("HTTP request body timeout.");
         return true;
       } else {
diff --git a/src/HttpServerBodyCommand.h b/src/HttpServerBodyCommand.h
index 1e5c3834..b117dbc1 100644
--- a/src/HttpServerBodyCommand.h
+++ b/src/HttpServerBodyCommand.h
@@ -37,7 +37,7 @@
 
 #include "Command.h"
 #include "SharedHandle.h"
-#include "TimeA2.h"
+#include "TimerA2.h"
 
 namespace aria2 {
 
@@ -50,7 +50,7 @@ private:
   DownloadEngine* _e;
   SharedHandle<SocketCore> _socket;
   SharedHandle<HttpServer> _httpServer;
-  Time _timeout;
+  Timer _timeoutTimer;
 public:
   HttpServerBodyCommand(cuid_t cuid,
                         const SharedHandle<HttpServer>& httpServer,
diff --git a/src/HttpServerCommand.cc b/src/HttpServerCommand.cc
index 13ba4730..6a65c8b0 100644
--- a/src/HttpServerCommand.cc
+++ b/src/HttpServerCommand.cc
@@ -93,7 +93,7 @@ bool HttpServerCommand::execute()
   }
   try {
     if(_socket->isReadable(0)) {
-      _timeout = global::wallclock;
+      _timeoutTimer = global::wallclock;
       SharedHandle<HttpHeader> header;
 
       header = _httpServer->receiveRequest();
@@ -128,7 +128,7 @@ bool HttpServerCommand::execute()
       _e->setNoWait(true);
       return true;
     } else {
-      if(_timeout.difference(global::wallclock) >= 30) {
+      if(_timeoutTimer.difference(global::wallclock) >= 30) {
         logger->info("HTTP request timeout.");
         return true;
       } else {
diff --git a/src/HttpServerCommand.h b/src/HttpServerCommand.h
index 09181f80..d1d6de30 100644
--- a/src/HttpServerCommand.h
+++ b/src/HttpServerCommand.h
@@ -37,7 +37,7 @@
 
 #include "Command.h"
 #include "SharedHandle.h"
-#include "TimeA2.h"
+#include "TimerA2.h"
 
 namespace aria2 {
 
@@ -50,7 +50,7 @@ private:
   DownloadEngine* _e;
   SharedHandle<SocketCore> _socket;
   SharedHandle<HttpServer> _httpServer;
-  Time _timeout;
+  Timer _timeoutTimer;
 public:
   HttpServerCommand(cuid_t cuid, DownloadEngine* e,
                     const SharedHandle<SocketCore>& socket);
diff --git a/src/HttpServerResponseCommand.cc b/src/HttpServerResponseCommand.cc
index 06d724c7..e3a163f5 100644
--- a/src/HttpServerResponseCommand.cc
+++ b/src/HttpServerResponseCommand.cc
@@ -93,7 +93,7 @@ bool HttpServerResponseCommand::execute()
     }
     return true;
   } else {
-    if(_timeout.difference(global::wallclock) >= 10) {
+    if(_timeoutTimer.difference(global::wallclock) >= 10) {
       if(logger->info()) {
         logger->info("CUID#%s - HttpServer: Timeout while trasmitting"
                      " response.", util::itos(cuid).c_str());
diff --git a/src/HttpServerResponseCommand.h b/src/HttpServerResponseCommand.h
index 7fc0eaca..ad654ae3 100644
--- a/src/HttpServerResponseCommand.h
+++ b/src/HttpServerResponseCommand.h
@@ -37,7 +37,7 @@
 
 #include "Command.h"
 #include "SharedHandle.h"
-#include "TimeA2.h"
+#include "TimerA2.h"
 
 namespace aria2 {
 
@@ -50,7 +50,7 @@ private:
   DownloadEngine* _e;
   SharedHandle<SocketCore> _socket;
   SharedHandle<HttpServer> _httpServer;
-  Time _timeout;
+  Timer _timeoutTimer;
 public:
   HttpServerResponseCommand(cuid_t cuid,
                             const SharedHandle<HttpServer>& httpServer,
diff --git a/src/LpdMessageDispatcher.h b/src/LpdMessageDispatcher.h
index bb6bad52..3b35f99e 100644
--- a/src/LpdMessageDispatcher.h
+++ b/src/LpdMessageDispatcher.h
@@ -38,7 +38,7 @@
 #include <string>
 
 #include "SharedHandle.h"
-#include "TimeA2.h"
+#include "TimerA2.h"
 
 namespace aria2 {
 
@@ -52,7 +52,7 @@ private:
   uint16_t _port;
   std::string _multicastAddress;
   uint16_t _multicastPort;
-  Time _timer;
+  Timer _timer;
   time_t _interval;
   std::string _request;
   Logger* _logger;
diff --git a/src/Makefile.am b/src/Makefile.am
index bd527c6f..d1d89de4 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -51,6 +51,7 @@ SRCS =  Socket.h\
 	Base64.cc Base64.h\
 	base32.cc base32.h\
 	LogFactory.cc LogFactory.h\
+	TimerA2.cc TimerA2.h\
 	TimeA2.cc TimeA2.h\
 	SharedHandle.h\
 	HandleRegistry.h\
diff --git a/src/Makefile.in b/src/Makefile.in
index aca935f9..858c0658 100644
--- a/src/Makefile.in
+++ b/src/Makefile.in
@@ -341,9 +341,9 @@ am__libaria2c_a_SOURCES_DIST = Socket.h SocketCore.cc SocketCore.h \
 	DefaultDiskWriter.cc DefaultDiskWriter.h \
 	DefaultDiskWriterFactory.cc DefaultDiskWriterFactory.h File.cc \
 	File.h Option.cc Option.h Base64.cc Base64.h base32.cc \
-	base32.h LogFactory.cc LogFactory.h TimeA2.cc TimeA2.h \
-	SharedHandle.h HandleRegistry.h FeatureConfig.cc \
-	FeatureConfig.h DownloadEngineFactory.cc \
+	base32.h LogFactory.cc LogFactory.h TimerA2.cc TimerA2.h \
+	TimeA2.cc TimeA2.h SharedHandle.h HandleRegistry.h \
+	FeatureConfig.cc FeatureConfig.h DownloadEngineFactory.cc \
 	DownloadEngineFactory.h SpeedCalc.cc SpeedCalc.h PeerStat.h \
 	BitfieldMan.cc BitfieldMan.h Randomizer.h SimpleRandomizer.cc \
 	SimpleRandomizer.h HttpResponse.cc HttpResponse.h \
@@ -800,11 +800,12 @@ am__objects_27 = SocketCore.$(OBJEXT) Command.$(OBJEXT) \
 	SimpleLogger.$(OBJEXT) AbstractDiskWriter.$(OBJEXT) \
 	DefaultDiskWriter.$(OBJEXT) DefaultDiskWriterFactory.$(OBJEXT) \
 	File.$(OBJEXT) Option.$(OBJEXT) Base64.$(OBJEXT) \
-	base32.$(OBJEXT) LogFactory.$(OBJEXT) TimeA2.$(OBJEXT) \
-	FeatureConfig.$(OBJEXT) DownloadEngineFactory.$(OBJEXT) \
-	SpeedCalc.$(OBJEXT) BitfieldMan.$(OBJEXT) \
-	SimpleRandomizer.$(OBJEXT) HttpResponse.$(OBJEXT) \
-	HttpRequest.$(OBJEXT) AbstractProxyRequestCommand.$(OBJEXT) \
+	base32.$(OBJEXT) LogFactory.$(OBJEXT) TimerA2.$(OBJEXT) \
+	TimeA2.$(OBJEXT) FeatureConfig.$(OBJEXT) \
+	DownloadEngineFactory.$(OBJEXT) SpeedCalc.$(OBJEXT) \
+	BitfieldMan.$(OBJEXT) SimpleRandomizer.$(OBJEXT) \
+	HttpResponse.$(OBJEXT) HttpRequest.$(OBJEXT) \
+	AbstractProxyRequestCommand.$(OBJEXT) \
 	AbstractProxyResponseCommand.$(OBJEXT) Netrc.$(OBJEXT) \
 	AuthConfig.$(OBJEXT) AbstractAuthResolver.$(OBJEXT) \
 	DefaultAuthResolver.$(OBJEXT) NetrcAuthResolver.$(OBJEXT) \
@@ -1103,9 +1104,9 @@ SRCS = Socket.h SocketCore.cc SocketCore.h BinaryStream.h Command.cc \
 	DefaultDiskWriter.cc DefaultDiskWriter.h \
 	DefaultDiskWriterFactory.cc DefaultDiskWriterFactory.h File.cc \
 	File.h Option.cc Option.h Base64.cc Base64.h base32.cc \
-	base32.h LogFactory.cc LogFactory.h TimeA2.cc TimeA2.h \
-	SharedHandle.h HandleRegistry.h FeatureConfig.cc \
-	FeatureConfig.h DownloadEngineFactory.cc \
+	base32.h LogFactory.cc LogFactory.h TimerA2.cc TimerA2.h \
+	TimeA2.cc TimeA2.h SharedHandle.h HandleRegistry.h \
+	FeatureConfig.cc FeatureConfig.h DownloadEngineFactory.cc \
 	DownloadEngineFactory.h SpeedCalc.cc SpeedCalc.h PeerStat.h \
 	BitfieldMan.cc BitfieldMan.h Randomizer.h SimpleRandomizer.cc \
 	SimpleRandomizer.h HttpResponse.cc HttpResponse.h \
@@ -1573,6 +1574,7 @@ distclean-compile:
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/TimeA2.Po@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/TimeBasedCommand.Po@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/TimedHaltCommand.Po@am__quote@
+@AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/TimerA2.Po@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/TrackerWatcherCommand.Po@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/TransferStat.Po@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/URIResult.Po@am__quote@
diff --git a/src/Peer.cc b/src/Peer.cc
index ee2014a9..8913d254 100644
--- a/src/Peer.cc
+++ b/src/Peer.cc
@@ -370,13 +370,13 @@ bool Peer::isDHTEnabled() const
   return _res->dhtEnabled();
 }
 
-const Time& Peer::getLastDownloadUpdate() const
+const Timer& Peer::getLastDownloadUpdate() const
 {
   assert(_res);
   return _res->getLastDownloadUpdate();
 }
 
-const Time& Peer::getLastAmUnchoking() const
+const Timer& Peer::getLastAmUnchoking() const
 {
   assert(_res);
   return _res->getLastAmUnchoking();
@@ -393,7 +393,7 @@ void Peer::setIncomingPeer(bool incoming)
   _incoming = incoming;
 }
 
-void Peer::setFirstContactTime(const Time& time)
+void Peer::setFirstContactTime(const Timer& time)
 {
   _firstContactTime = time;
 }
diff --git a/src/Peer.h b/src/Peer.h
index 965f0b11..c32227a5 100644
--- a/src/Peer.h
+++ b/src/Peer.h
@@ -43,7 +43,7 @@
 #include <algorithm>
 
 #include "SharedHandle.h"
-#include "TimeA2.h"
+#include "TimerA2.h"
 #include "BtConstants.h"
 #include "PeerStat.h"
 #include "a2functional.h"
@@ -68,9 +68,9 @@ private:
 
   unsigned char _peerId[PEER_ID_LENGTH];
 
-  Time _firstContactTime;
+  Timer _firstContactTime;
 
-  Time _badConditionStartTime;
+  Timer _badConditionStartTime;
 
   bool _seeder;
 
@@ -146,14 +146,14 @@ public:
 
   void releaseSessionResource();
 
-  const Time& getFirstContactTime() const
+  const Timer& getFirstContactTime() const
   {
     return _firstContactTime;
   }
 
-  void setFirstContactTime(const Time& time);
+  void setFirstContactTime(const Timer& time);
 
-  const Time& getBadConditionStartTime() const
+  const Timer& getBadConditionStartTime() const
   {
     return _badConditionStartTime;
   }
@@ -269,9 +269,9 @@ public:
 
   void setExtension(const std::string& name, uint8_t id);
 
-  const Time& getLastDownloadUpdate() const;
+  const Timer& getLastDownloadUpdate() const;
 
-  const Time& getLastAmUnchoking() const;
+  const Timer& getLastAmUnchoking() const;
 
   uint64_t getCompletedLength() const;
 
diff --git a/src/PeerAbstractCommand.h b/src/PeerAbstractCommand.h
index f8618b7a..26098f72 100644
--- a/src/PeerAbstractCommand.h
+++ b/src/PeerAbstractCommand.h
@@ -37,7 +37,7 @@
 
 #include "Command.h"
 #include "SharedHandle.h"
-#include "TimeA2.h"
+#include "TimerA2.h"
 
 namespace aria2 {
 
@@ -48,7 +48,7 @@ class SocketCore;
 
 class PeerAbstractCommand : public Command {
 private:
-  Time checkPoint;
+  Timer checkPoint;
   time_t timeout;
 protected:
   DownloadEngine* e;
diff --git a/src/PeerAddrEntry.h b/src/PeerAddrEntry.h
index 9440a17e..8bc146e3 100644
--- a/src/PeerAddrEntry.h
+++ b/src/PeerAddrEntry.h
@@ -36,9 +36,11 @@
 #define _D_DHT_PEER_ADDR_ENTRY_H_
 
 #include "common.h"
-#include "TimeA2.h"
+
 #include <string>
 
+#include "TimerA2.h"
+
 namespace aria2 {
 
 class PeerAddrEntry {
@@ -47,9 +49,10 @@ private:
   
   uint16_t _port;
 
-  Time _lastUpdated;
+  Timer _lastUpdated;
 public:
-  PeerAddrEntry(const std::string& ipaddr, uint16_t port, Time updated = Time()):
+  PeerAddrEntry
+  (const std::string& ipaddr, uint16_t port, Timer updated = Timer()):
     _ipaddr(ipaddr), _port(port), _lastUpdated(updated) {}
 
   const std::string& getIPAddress() const
@@ -62,7 +65,7 @@ public:
     return _port;
   }
 
-  const Time& getLastUpdated() const
+  const Timer& getLastUpdated() const
   {
     return _lastUpdated;
   }
diff --git a/src/PeerSessionResource.h b/src/PeerSessionResource.h
index 7e191275..1cdf358e 100644
--- a/src/PeerSessionResource.h
+++ b/src/PeerSessionResource.h
@@ -42,7 +42,7 @@
 
 #include "BtConstants.h"
 #include "PeerStat.h"
-#include "TimeA2.h"
+#include "TimerA2.h"
 
 namespace aria2 {
 
@@ -77,9 +77,9 @@ private:
   bool _dhtEnabled;
   PeerStat _peerStat;
 
-  Time _lastDownloadUpdate;
+  Timer _lastDownloadUpdate;
 
-  Time _lastAmUnchoking;
+  Timer _lastAmUnchoking;
 
   WeakHandle<BtMessageDispatcher> _dispatcher;
 public:
@@ -216,12 +216,12 @@ public:
 
   void updateDownloadLength(size_t bytes);
 
-  const Time& getLastDownloadUpdate() const
+  const Timer& getLastDownloadUpdate() const
   {
     return _lastDownloadUpdate;
   }
 
-  const Time& getLastAmUnchoking() const
+  const Timer& getLastAmUnchoking() const
   {
     return _lastAmUnchoking;
   }
diff --git a/src/PeerStat.h b/src/PeerStat.h
index 11d2119d..087a4f17 100644
--- a/src/PeerStat.h
+++ b/src/PeerStat.h
@@ -57,7 +57,7 @@ private:
   std::string _protocol;
   SpeedCalc downloadSpeed;
   SpeedCalc uploadSpeed;
-  Time downloadStartTime;
+  Timer downloadStartTime;
   PeerStat::STATUS status;
   unsigned int _avgDownloadSpeed;
   unsigned int _avgUploadSpeed;
@@ -147,7 +147,7 @@ public:
     status = PeerStat::IDLE;
   }
 
-  const Time& getDownloadStartTime() const {
+  const Timer& getDownloadStartTime() const {
     return downloadStartTime;
   }
 
diff --git a/src/PieceStorage.h b/src/PieceStorage.h
index 0c30139d..62734dd0 100644
--- a/src/PieceStorage.h
+++ b/src/PieceStorage.h
@@ -41,7 +41,7 @@
 #include <vector>
 
 #include "SharedHandle.h"
-#include "TimeA2.h"
+#include "TimerA2.h"
 #include "Command.h"
 
 namespace aria2 {
@@ -207,7 +207,7 @@ public:
    */
   virtual void getAdvertisedPieceIndexes(std::vector<size_t>& indexes,
                                          cuid_t myCuid,
-                                         const Time& lastCheckTime) = 0;
+                                         const Timer& lastCheckTime) = 0;
 
   /**
    * Removes have entry if specified seconds have elapsed since its
diff --git a/src/RequestSlot.cc b/src/RequestSlot.cc
index d10f15cc..4bf9cda6 100644
--- a/src/RequestSlot.cc
+++ b/src/RequestSlot.cc
@@ -39,12 +39,8 @@ namespace aria2 {
 
 RequestSlot RequestSlot::nullSlot = RequestSlot();
 
-void RequestSlot::setDispatchedTime() {
-  dispatchedTime = global::wallclock;
-}
-
-void RequestSlot::setDispatchedTime(time_t secFromEpoch) {
-  dispatchedTime.setTimeInSec(secFromEpoch);
+void RequestSlot::setDispatchedTime(time_t sec) {
+  dispatchedTime.reset(sec);
 }
 
 bool RequestSlot::isTimeout(time_t timeoutSec) const {
diff --git a/src/RequestSlot.h b/src/RequestSlot.h
index 372b4641..6d3d75a8 100644
--- a/src/RequestSlot.h
+++ b/src/RequestSlot.h
@@ -36,14 +36,15 @@
 #define _D_REQUEST_SLOT_H_
 
 #include "common.h"
-#include "TimeA2.h"
+#include "TimerA2.h"
 #include "Piece.h"
+#include "wallclock.h"
 
 namespace aria2 {
 
 class RequestSlot {
 private:
-  Time dispatchedTime;
+  Timer dispatchedTime;
   size_t index;
   uint32_t begin;
   size_t length;
@@ -70,6 +71,7 @@ public:
   
   RequestSlot(size_t index, uint32_t begin, size_t length, size_t blockIndex,
               const SharedHandle<Piece>& piece = SharedHandle<Piece>()):
+    dispatchedTime(global::wallclock),
     index(index), begin(begin), length(length), blockIndex(blockIndex),
     _piece(piece) {}
 
@@ -113,7 +115,6 @@ public:
     }
   }
 
-  void setDispatchedTime();
   void setDispatchedTime(time_t secFromEpoch);
 
   bool isTimeout(time_t timeoutSec) const;
diff --git a/src/SegmentMan.h b/src/SegmentMan.h
index ccac611c..b9e8f694 100644
--- a/src/SegmentMan.h
+++ b/src/SegmentMan.h
@@ -42,7 +42,7 @@
 #include <map>
 
 #include "SharedHandle.h"
-#include "TimeA2.h"
+#include "TimerA2.h"
 #include "Command.h"
 #include "BitfieldMan.h"
 
@@ -98,7 +98,7 @@ private:
   // key: PeerStat's cuid, value: its download speed
   std::map<cuid_t, unsigned int> _peerStatDlspdMap;
 
-  Time _lastPeerStatDlspdMapUpdated;
+  Timer _lastPeerStatDlspdMapUpdated;
 
   unsigned int _cachedDlspd;
 
diff --git a/src/ServerStat.cc b/src/ServerStat.cc
index b5c9a0a5..2103ed7f 100644
--- a/src/ServerStat.cc
+++ b/src/ServerStat.cc
@@ -39,7 +39,6 @@
 
 #include "array_fun.h"
 #include "LogFactory.h"
-#include "wallclock.h"
 
 namespace aria2 {
 
@@ -78,7 +77,7 @@ void ServerStat::updateDownloadSpeed(unsigned int downloadSpeed)
   if(downloadSpeed > 0) {
     _status = OK;
   }
-  _lastUpdated = global::wallclock;
+  _lastUpdated.reset();
 }
 
 void ServerStat::setSingleConnectionAvgSpeed
@@ -183,7 +182,7 @@ void ServerStat::setStatusInternal(STATUS status)
                    _hostname.c_str(), _protocol.c_str());
   }
   _status = status;
-  _lastUpdated = global::wallclock;
+  _lastUpdated.reset();
 }
 
 void ServerStat::setOK()
diff --git a/src/ServerStatMan.cc b/src/ServerStatMan.cc
index 23af57d5..ca27eb58 100644
--- a/src/ServerStatMan.cc
+++ b/src/ServerStatMan.cc
@@ -43,7 +43,6 @@
 #include "ServerStat.h"
 #include "util.h"
 #include "RecoverableException.h"
-#include "wallclock.h"
 
 namespace aria2 {
 
@@ -144,12 +143,13 @@ bool ServerStatMan::load(std::istream& in)
 class FindStaleServerStat {
 private:
   time_t _timeout;
+  Time _time;
 public:
   FindStaleServerStat(time_t timeout):_timeout(timeout) {}
 
   bool operator()(const SharedHandle<ServerStat>& ss) const
   {
-    return ss->getLastUpdated().difference(global::wallclock) >= _timeout;
+    return ss->getLastUpdated().difference(_time) >= _timeout;
   }
 };
 
diff --git a/src/ServerStatMan.h b/src/ServerStatMan.h
index 8bd29a4f..4eb1fe06 100644
--- a/src/ServerStatMan.h
+++ b/src/ServerStatMan.h
@@ -35,11 +35,14 @@
 #ifndef _D_SERVER_STAT_MAN_H_
 #define _D_SERVER_STAT_MAN_H_
 #include "common.h"
-#include "SharedHandle.h"
+
 #include <string>
 #include <deque>
 #include <iosfwd>
 
+#include "SharedHandle.h"
+#include "a2time.h"
+
 namespace aria2 {
 
 class ServerStat;
diff --git a/src/SleepCommand.cc b/src/SleepCommand.cc
index 78811de1..e8a85ae5 100644
--- a/src/SleepCommand.cc
+++ b/src/SleepCommand.cc
@@ -44,7 +44,7 @@ SleepCommand::SleepCommand(cuid_t cuid, DownloadEngine* e,
                            RequestGroup* requestGroup,
                            Command* nextCommand, time_t wait):
   Command(cuid), engine(e), _requestGroup(requestGroup),
-  nextCommand(nextCommand), wait(wait) {}
+  nextCommand(nextCommand), wait(wait), checkPoint(global::wallclock) {}
 
 SleepCommand::~SleepCommand() {
   delete nextCommand;
diff --git a/src/SleepCommand.h b/src/SleepCommand.h
index 0bf80ef8..ccf34fe1 100644
--- a/src/SleepCommand.h
+++ b/src/SleepCommand.h
@@ -36,7 +36,7 @@
 #define _D_SLEEP_COMMAND_H_
 
 #include "Command.h"
-#include "TimeA2.h"
+#include "TimerA2.h"
 
 namespace aria2 {
 
@@ -49,7 +49,7 @@ private:
   RequestGroup* _requestGroup;
   Command* nextCommand;
   time_t wait;
-  Time checkPoint;
+  Timer checkPoint;
 public:
   SleepCommand(cuid_t cuid, DownloadEngine* e, RequestGroup* requestGroup,
                Command* nextCommand, time_t wait);
diff --git a/src/SpeedCalc.h b/src/SpeedCalc.h
index 40a18e2c..d8fcae1f 100644
--- a/src/SpeedCalc.h
+++ b/src/SpeedCalc.h
@@ -36,7 +36,7 @@
 #define _D_SPEED_CALC_H_
 
 #include "common.h"
-#include "TimeA2.h"
+#include "TimerA2.h"
 
 namespace aria2 {
 
@@ -44,10 +44,10 @@ class SpeedCalc {
 private:
   uint64_t lengthArray[2];
   int sw;
-  Time cpArray[2];
+  Timer cpArray[2];
   unsigned int maxSpeed;
   unsigned int prevSpeed;
-  Time start;
+  Timer start;
   uint64_t accumulatedLength;
   time_t nextInterval;
 
diff --git a/src/StreamCheckIntegrityEntry.h b/src/StreamCheckIntegrityEntry.h
index 81f48a7c..c231e4c6 100644
--- a/src/StreamCheckIntegrityEntry.h
+++ b/src/StreamCheckIntegrityEntry.h
@@ -36,14 +36,11 @@
 #define _D_STREAM_CHECK_INTEGRITY_ENTRY_H_
 
 #include "PieceHashCheckIntegrityEntry.h"
-#include "TimeA2.h"
 
 namespace aria2 {
 
 class StreamCheckIntegrityEntry:public PieceHashCheckIntegrityEntry
 {
-private:
-  Time _timer;
 public:
   StreamCheckIntegrityEntry(RequestGroup* requestGroup,
                             Command* nextCommand = 0);
diff --git a/src/StreamFileAllocationEntry.h b/src/StreamFileAllocationEntry.h
index e982d98f..e277705e 100644
--- a/src/StreamFileAllocationEntry.h
+++ b/src/StreamFileAllocationEntry.h
@@ -36,13 +36,10 @@
 #define _D_STREAM_FILE_ALLOCATION_ENTRY_H_
 
 #include "FileAllocationEntry.h"
-#include "TimeA2.h"
 
 namespace aria2 {
 
 class StreamFileAllocationEntry : public FileAllocationEntry {
-private:
-  Time _timer;
 public:
   StreamFileAllocationEntry(RequestGroup* requestGroup,
                             Command* nextCommand = 0);
diff --git a/src/TimeBasedCommand.h b/src/TimeBasedCommand.h
index f08a9af1..dc5f0c38 100644
--- a/src/TimeBasedCommand.h
+++ b/src/TimeBasedCommand.h
@@ -36,7 +36,7 @@
 #define _D_TIME_BASED_COMMAND_H_
 
 #include "Command.h"
-#include "TimeA2.h"
+#include "TimerA2.h"
 
 namespace aria2 {
 
@@ -60,7 +60,7 @@ protected:
 
   bool _routineCommand;
 private:
-  Time _checkPoint;
+  Timer _checkPoint;
 public:
   /**
    * preProcess() is called each time when excute() is called.
diff --git a/src/TimeSeedCriteria.h b/src/TimeSeedCriteria.h
index 1c74649e..53d56312 100644
--- a/src/TimeSeedCriteria.h
+++ b/src/TimeSeedCriteria.h
@@ -36,7 +36,7 @@
 #define _D_TIME_SEED_CRITERIA_H_
 
 #include "SeedCriteria.h"
-#include "TimeA2.h"
+#include "TimerA2.h"
 #include "wallclock.h"
 
 namespace aria2 {
@@ -45,7 +45,7 @@ class TimeSeedCriteria : public SeedCriteria {
 private:
   // How much time the client does seeding in seconds.
   time_t duration;
-  Time watch;
+  Timer watch;
 public:
   TimeSeedCriteria(time_t duration):duration(duration) {}
   virtual ~TimeSeedCriteria() {}
diff --git a/src/TimerA2.cc b/src/TimerA2.cc
new file mode 100644
index 00000000..4da4d6fc
--- /dev/null
+++ b/src/TimerA2.cc
@@ -0,0 +1,165 @@
+/* <!-- copyright */
+/*
+ * aria2 - The high speed download utility
+ *
+ * Copyright (C) 2010 Tatsuhiro Tsujikawa
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ *
+ * In addition, as a special exception, the copyright holders give
+ * permission to link the code of portions of this program with the
+ * OpenSSL library under certain conditions as described in each
+ * individual source file, and distribute linked combinations
+ * including the two.
+ * You must obey the GNU General Public License in all respects
+ * for all of the code used other than OpenSSL.  If you modify
+ * file(s) with this exception, you may extend this exception to your
+ * version of the file(s), but you are not obligated to do so.  If you
+ * do not wish to do so, delete this exception statement from your
+ * version.  If you delete this exception statement from all source
+ * files in the program, then also delete it here.
+ */
+/* copyright --> */
+
+#include "TimerA2.h"
+
+#include <cassert>
+
+#include "util.h"
+
+namespace aria2 {
+
+Timer::Timer()
+{
+  reset();
+}
+
+Timer::Timer(const Timer& timer):_tv(timer._tv) {}
+
+Timer::Timer(time_t sec)
+{
+  reset(sec);
+}
+
+Timer::Timer(const struct timeval& tv):_tv(tv) {}
+
+static bool useClockGettime()
+{
+  static timespec ts;
+  static int r = clock_gettime(CLOCK_MONOTONIC, &ts);
+  return r == 0;
+}
+
+Timer& Timer::operator=(const Timer& timer)
+{
+  if(this != &timer) {
+    _tv = timer._tv;
+  }
+  return *this;
+}
+
+bool Timer::operator<(const Timer& timer) const
+{
+  return util::difftv(timer._tv, _tv) > 0;
+}
+
+bool Timer::operator>(const Timer& timer) const
+{
+  return util::difftv(_tv, timer._tv) > 0;
+}
+
+static timeval getCurrentTime()
+{
+  timeval tv;
+  if(useClockGettime()) {
+    timespec ts;
+    int r = clock_gettime(CLOCK_MONOTONIC, &ts);
+    assert(r == 0);
+    tv.tv_sec = ts.tv_sec+2678400; // 1month offset(24*3600*31)
+    tv.tv_usec = ts.tv_nsec/1000;
+  } else {
+    gettimeofday(&tv, 0);
+  }
+  return tv;
+}
+
+void Timer::reset()
+{
+  _tv = getCurrentTime();
+}
+
+void Timer::reset(time_t sec)
+{
+  _tv.tv_sec = sec;
+  _tv.tv_usec = 0;
+}
+
+bool Timer::elapsed(time_t sec) const
+{
+  return
+    util::difftv(getCurrentTime(), _tv) >= static_cast<int64_t>(sec)*1000000;
+}
+
+bool Timer::elapsedInMillis(int64_t millis) const
+{
+  return util::difftv(getCurrentTime(), _tv)/1000 >= millis;
+}
+
+time_t Timer::difference() const
+{
+  return util::difftv(getCurrentTime(), _tv)/1000000;
+}
+
+time_t Timer::difference(const timeval& tv) const
+{
+  return util::difftv(tv, _tv)/1000000;
+}
+
+int64_t Timer::differenceInMillis() const
+{
+  return util::difftv(getCurrentTime(), _tv)/1000;
+}
+
+int64_t Timer::differenceInMillis(const timeval& tv) const
+{
+  return util::difftv(tv, _tv)/1000;
+}
+
+bool Timer::isZero() const
+{
+  return _tv.tv_sec == 0 && _tv.tv_usec == 0;
+}
+
+int64_t Timer::getTimeInMicros() const
+{
+  return (int64_t)_tv.tv_sec*1000*1000+_tv.tv_usec;
+}
+
+int64_t Timer::getTimeInMillis() const
+{
+  return (int64_t)_tv.tv_sec*1000+_tv.tv_usec/1000;
+}
+
+time_t Timer::getTime() const
+{
+  return _tv.tv_sec;
+}
+
+void Timer::advance(time_t sec)
+{
+  _tv.tv_sec += sec;
+}
+
+} // namespace aria2
diff --git a/src/TimerA2.h b/src/TimerA2.h
new file mode 100644
index 00000000..0091e57a
--- /dev/null
+++ b/src/TimerA2.h
@@ -0,0 +1,101 @@
+/* <!-- copyright */
+/*
+ * aria2 - The high speed download utility
+ *
+ * Copyright (C) 2010 Tatsuhiro Tsujikawa
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ *
+ * In addition, as a special exception, the copyright holders give
+ * permission to link the code of portions of this program with the
+ * OpenSSL library under certain conditions as described in each
+ * individual source file, and distribute linked combinations
+ * including the two.
+ * You must obey the GNU General Public License in all respects
+ * for all of the code used other than OpenSSL.  If you modify
+ * file(s) with this exception, you may extend this exception to your
+ * version of the file(s), but you are not obligated to do so.  If you
+ * do not wish to do so, delete this exception statement from your
+ * version.  If you delete this exception statement from all source
+ * files in the program, then also delete it here.
+ */
+/* copyright --> */
+#ifndef _D_TIMER_A2_H_
+#define _D_TIMER_A2_H_
+
+#include "common.h"
+#include "a2time.h"
+
+namespace aria2 {
+
+class Timer {
+private:
+  timeval _tv;
+
+  int64_t difference(const struct timeval& tv) const;
+
+  int64_t differenceInMillis(const struct timeval& tv) const;
+public:
+  // The time value is initialized so that it represents the time at which
+  // this object was created.
+  Timer();
+  Timer(const Timer& time);
+  Timer(time_t sec);
+  Timer(const struct timeval& tv);
+
+  Timer& operator=(const Timer& timer);
+
+  bool operator<(const Timer& timer) const;
+
+  bool operator>(const Timer& timer) const;
+
+  void reset();
+
+  void reset(time_t sec);
+
+  bool elapsed(time_t sec) const;
+
+  bool elapsedInMillis(int64_t millis) const;
+
+  time_t difference() const;
+
+  time_t difference(const Timer& timer) const
+  {
+    return difference(timer._tv);
+  }
+
+  int64_t differenceInMillis() const;
+
+  int64_t differenceInMillis(const Timer& timer) const
+  {
+    return differenceInMillis(timer._tv);
+  }
+
+  // Returns true if this object's time value is zero.
+  bool isZero() const;
+
+  void advance(time_t sec);
+
+  // Returns this object's time value in seconds.
+  time_t getTime() const;
+
+  int64_t getTimeInMicros() const;
+
+  int64_t getTimeInMillis() const;
+};
+
+} // namespace aria2
+
+#endif // _D_TIMER_A2_H_
diff --git a/src/UTMetadataRequestTracker.h b/src/UTMetadataRequestTracker.h
index 3b197d63..b7bd91a5 100644
--- a/src/UTMetadataRequestTracker.h
+++ b/src/UTMetadataRequestTracker.h
@@ -39,7 +39,7 @@
 
 #include <vector>
 
-#include "TimeA2.h"
+#include "TimerA2.h"
 #include "wallclock.h"
 
 namespace aria2 {
@@ -50,7 +50,7 @@ class UTMetadataRequestTracker {
 private:
   struct RequestEntry {
     size_t _index;
-    Time _dispatchedTime;
+    Timer _dispatchedTime;
 
     RequestEntry(size_t index):_index(index) {}
 
diff --git a/src/UnknownLengthPieceStorage.h b/src/UnknownLengthPieceStorage.h
index 9015689d..8a82e4c3 100644
--- a/src/UnknownLengthPieceStorage.h
+++ b/src/UnknownLengthPieceStorage.h
@@ -229,7 +229,7 @@ public:
    */
   virtual void
   getAdvertisedPieceIndexes(std::vector<size_t>& indexes,
-                            cuid_t myCuid, const Time& lastCheckTime)
+                            cuid_t myCuid, const Timer& lastCheckTime)
   {}
 
   /**
diff --git a/src/a2time.h b/src/a2time.h
index 04822803..bf9628d2 100644
--- a/src/a2time.h
+++ b/src/a2time.h
@@ -61,4 +61,14 @@
 # define suseconds_t uint64_t
 #endif
 
+#ifndef CLOCK_MONOTONIC
+# define CLOCK_MONOTONIC 0
+#endif // !CLOCK_MONOTONIC
+#ifndef HAVE_STRUCT_TIMESPEC
+# define timespec int
+#endif // !HAVE_STRUCT_TIMESPEC
+#ifndef HAVE_CLOCK_GETTIME
+# define clock_gettime(ID, TP) (-1)
+#endif // !HAVE_CLOCK_GETTIME
+
 #endif // _D_A2TIME_H_
diff --git a/src/wallclock.h b/src/wallclock.h
index 5eab97ee..759c2768 100644
--- a/src/wallclock.h
+++ b/src/wallclock.h
@@ -32,14 +32,14 @@
  * files in the program, then also delete it here.
  */
 /* copyright --> */
-#include "TimeA2.h"
+#include "TimerA2.h"
 
 namespace aria2 {
 
 namespace global {
 
 // wallclock is defined in DownloadEngine.cc
-extern Time wallclock;
+extern Timer wallclock;
 
 } // namespace global
 
diff --git a/test/DHTPeerAnnounceEntryTest.cc b/test/DHTPeerAnnounceEntryTest.cc
index fd53c35c..299af7df 100644
--- a/test/DHTPeerAnnounceEntryTest.cc
+++ b/test/DHTPeerAnnounceEntryTest.cc
@@ -36,9 +36,9 @@ void DHTPeerAnnounceEntryTest::testRemoveStalePeerAddrEntry()
   DHTPeerAnnounceEntry entry(infohash);
 
   entry.addPeerAddrEntry(PeerAddrEntry("192.168.0.1", 6881));
-  entry.addPeerAddrEntry(PeerAddrEntry("192.168.0.2", 6882, Time(0)));
+  entry.addPeerAddrEntry(PeerAddrEntry("192.168.0.2", 6882, Timer(0)));
   entry.addPeerAddrEntry(PeerAddrEntry("192.168.0.3", 6883));
-  entry.addPeerAddrEntry(PeerAddrEntry("192.168.0.4", 6884, Time(0)));
+  entry.addPeerAddrEntry(PeerAddrEntry("192.168.0.4", 6884, Timer(0)));
 
   entry.removeStalePeerAddrEntry(10);
 
@@ -72,7 +72,7 @@ void DHTPeerAnnounceEntryTest::testAddPeerAddrEntry()
   memset(infohash, 0xff, DHT_ID_LENGTH);
 
   DHTPeerAnnounceEntry entry(infohash);
-  entry.addPeerAddrEntry(PeerAddrEntry("192.168.0.1", 6881, Time(0)));
+  entry.addPeerAddrEntry(PeerAddrEntry("192.168.0.1", 6881, Timer(0)));
   entry.addPeerAddrEntry(PeerAddrEntry("192.168.0.1", 6882));
 
   CPPUNIT_ASSERT_EQUAL((size_t)2, entry.countPeerAddrEntry());
@@ -95,7 +95,7 @@ void DHTPeerAnnounceEntryTest::testGetPeers()
     CPPUNIT_ASSERT_EQUAL((size_t)0, peers.size());
   }
 
-  entry.addPeerAddrEntry(PeerAddrEntry("192.168.0.1", 6881, Time(0)));
+  entry.addPeerAddrEntry(PeerAddrEntry("192.168.0.1", 6881, Timer(0)));
   entry.addPeerAddrEntry(PeerAddrEntry("192.168.0.2", 6882));
 
   {
diff --git a/test/MockPieceStorage.h b/test/MockPieceStorage.h
index a6d09acf..00598455 100644
--- a/test/MockPieceStorage.h
+++ b/test/MockPieceStorage.h
@@ -214,7 +214,7 @@ public:
 
   virtual void getAdvertisedPieceIndexes(std::vector<size_t>& indexes,
                                          cuid_t myCuid,
-                                         const Time& lastCheckTime)
+                                         const Timer& lastCheckTime)
   {}
 
   virtual void removeAdvertisedPiece(time_t elapsed) {}
diff --git a/test/UTPexExtensionMessageTest.cc b/test/UTPexExtensionMessageTest.cc
index 13a38b62..f4d1f056 100644
--- a/test/UTPexExtensionMessageTest.cc
+++ b/test/UTPexExtensionMessageTest.cc
@@ -206,7 +206,7 @@ void UTPexExtensionMessageTest::testAddFreshPeer()
   SharedHandle<Peer> p1(new Peer("192.168.0.1", 6881));
   CPPUNIT_ASSERT(msg.addFreshPeer(p1));
   SharedHandle<Peer> p2(new Peer("10.1.1.2", 9999));
-  p2->setFirstContactTime(Time(Time().getTime()-61));
+  p2->setFirstContactTime(Timer(Timer().getTime()-61));
   CPPUNIT_ASSERT(!msg.addFreshPeer(p2));
   SharedHandle<Peer> p3(new Peer("10.1.1.3", 9999, true));
   CPPUNIT_ASSERT(!msg.addFreshPeer(p3));