diff --git a/bitbake/lib/prserv/__init__.py b/bitbake/lib/prserv/__init__.py
new file mode 100644
index 0000000..c3cb73a
--- /dev/null
+++ b/bitbake/lib/prserv/__init__.py
@@ -0,0 +1,14 @@
+__version__ = "1.0.0"
+
+import os, time
+import sys,logging
+
+def init_logger(logfile, loglevel):
+    numeric_level = getattr(logging, loglevel.upper(), None)
+    if not isinstance(numeric_level, int):
+        raise ValueError('Invalid log level: %s' % loglevel)
+    FORMAT = '%(asctime)-15s %(message)s'
+    logging.basicConfig(level=numeric_level, filename=logfile, format=FORMAT)
+
+class NotFoundError(Exception):
+    pass
diff --git a/bitbake/lib/prserv/db.py b/bitbake/lib/prserv/db.py
new file mode 100644
index 0000000..4379580
--- /dev/null
+++ b/bitbake/lib/prserv/db.py
@@ -0,0 +1,268 @@
+import logging
+import os.path
+import errno
+import prserv
+import time
+
+try:
+    import sqlite3
+except ImportError:
+    from pysqlite2 import dbapi2 as sqlite3
+
+logger = logging.getLogger("BitBake.PRserv")
+
+sqlversion = sqlite3.sqlite_version_info
+if sqlversion[0] < 3 or (sqlversion[0] == 3 and sqlversion[1] < 3):
+    raise Exception("sqlite3 version 3.3.0 or later is required.")
+
+#
+# "No History" mode - for a given query tuple (version, pkgarch, checksum),
+# the returned value will be the largest among all the values of the same
+# (version, pkgarch). This means the PR value returned can NOT be decremented.
+#
+# "History" mode - Return a new higher value for previously unseen query
+# tuple (version, pkgarch, checksum), otherwise return historical value.
+# Value can decrement if returning to a previous build.
+#
+
+class PRTable(object):
+    def __init__(self, conn, table, nohist):
+        self.conn = conn
+        self.nohist = nohist
+        self.dirty = False
+        if nohist:
+            self.table = "%s_nohist" % table 
+        else:
+            self.table = "%s_hist" % table 
+
+        self._execute("CREATE TABLE IF NOT EXISTS %s \
+                    (version TEXT NOT NULL, \
+                    pkgarch TEXT NOT NULL,  \
+                    checksum TEXT NOT NULL, \
+                    value INTEGER, \
+                    PRIMARY KEY (version, pkgarch, checksum));" % self.table)
+
+    def _execute(self, *query):
+        """Execute a query, waiting to acquire a lock if necessary"""
+        start = time.time()
+        end = start + 20
+        while True:
+            try:
+                return self.conn.execute(*query)
+            except sqlite3.OperationalError as exc:
+                if 'is locked' in str(exc) and end > time.time():
+                    continue
+                raise exc
+
+    def sync(self):
+        self.conn.commit()
+        self._execute("BEGIN EXCLUSIVE TRANSACTION")
+
+    def sync_if_dirty(self):
+        if self.dirty:
+            self.sync()
+            self.dirty = False
+
+    def _getValueHist(self, version, pkgarch, checksum):
+        data=self._execute("SELECT value FROM %s WHERE version=? AND pkgarch=? AND checksum=?;" % self.table,
+                           (version, pkgarch, checksum))
+        row=data.fetchone()
+        if row != None:
+            return row[0]
+        else:
+            #no value found, try to insert
+            try:
+                self._execute("INSERT INTO %s VALUES (?, ?, ?, (select ifnull(max(value)+1,0) from %s where version=? AND pkgarch=?));"
+                           % (self.table,self.table),
+                           (version,pkgarch, checksum,version, pkgarch))
+            except sqlite3.IntegrityError as exc:
+                logger.error(str(exc))
+
+            self.dirty = True
+
+            data=self._execute("SELECT value FROM %s WHERE version=? AND pkgarch=? AND checksum=?;" % self.table,
+                               (version, pkgarch, checksum))
+            row=data.fetchone()
+            if row != None:
+                return row[0]
+            else:
+                raise prserv.NotFoundError
+
+    def _getValueNohist(self, version, pkgarch, checksum):
+        data=self._execute("SELECT value FROM %s \
+                            WHERE version=? AND pkgarch=? AND checksum=? AND \
+                            value >= (select max(value) from %s where version=? AND pkgarch=?);" 
+                            % (self.table, self.table),
+                            (version, pkgarch, checksum, version, pkgarch))
+        row=data.fetchone()
+        if row != None:
+            return row[0]
+        else:
+            #no value found, try to insert
+            try:
+                self._execute("INSERT OR REPLACE INTO %s VALUES (?, ?, ?, (select ifnull(max(value)+1,0) from %s where version=? AND pkgarch=?));"
+                               % (self.table,self.table),
+                               (version, pkgarch, checksum, version, pkgarch))
+            except sqlite3.IntegrityError as exc:
+                logger.error(str(exc))
+                self.conn.rollback()
+
+            self.dirty = True
+
+            data=self._execute("SELECT value FROM %s WHERE version=? AND pkgarch=? AND checksum=?;" % self.table,
+                               (version, pkgarch, checksum))
+            row=data.fetchone()
+            if row != None:
+                return row[0]
+            else:
+                raise prserv.NotFoundError
+
+    def getValue(self, version, pkgarch, checksum):
+        if self.nohist:
+            return self._getValueNohist(version, pkgarch, checksum)
+        else:
+            return self._getValueHist(version, pkgarch, checksum)
+
+    def _importHist(self, version, pkgarch, checksum, value):
+        val = None 
+        data = self._execute("SELECT value FROM %s WHERE version=? AND pkgarch=? AND checksum=?;" % self.table,
+                           (version, pkgarch, checksum))
+        row = data.fetchone()
+        if row != None:
+            val=row[0]
+        else:
+            #no value found, try to insert
+            try:
+                self._execute("INSERT INTO %s VALUES (?, ?, ?, ?);"  % (self.table),
+                           (version, pkgarch, checksum, value))
+            except sqlite3.IntegrityError as exc:
+                logger.error(str(exc))
+
+            self.dirty = True
+
+            data = self._execute("SELECT value FROM %s WHERE version=? AND pkgarch=? AND checksum=?;" % self.table,
+                           (version, pkgarch, checksum))
+            row = data.fetchone()
+            if row != None:
+                val = row[0]
+        return val
+
+    def _importNohist(self, version, pkgarch, checksum, value):
+        try:
+            #try to insert
+            self._execute("INSERT INTO %s VALUES (?, ?, ?, ?);"  % (self.table),
+                           (version, pkgarch, checksum,value))
+        except sqlite3.IntegrityError as exc:
+            #already have the record, try to update
+            try:
+                self._execute("UPDATE %s SET value=? WHERE version=? AND pkgarch=? AND checksum=? AND value<?"  
+                              % (self.table),
+                               (value,version,pkgarch,checksum,value))
+            except sqlite3.IntegrityError as exc:
+                logger.error(str(exc))
+
+        self.dirty = True
+
+        data = self._execute("SELECT value FROM %s WHERE version=? AND pkgarch=? AND checksum=? AND value>=?;" % self.table,
+                            (version,pkgarch,checksum,value))
+        row=data.fetchone()
+        if row != None:
+            return row[0]
+        else:
+            return None
+
+    def importone(self, version, pkgarch, checksum, value):
+        if self.nohist:
+            return self._importNohist(version, pkgarch, checksum, value)
+        else:
+            return self._importHist(version, pkgarch, checksum, value)
+
+    def export(self, version, pkgarch, checksum, colinfo):
+        metainfo = {}
+        #column info 
+        if colinfo:
+            metainfo['tbl_name'] = self.table
+            metainfo['core_ver'] = prserv.__version__
+            metainfo['col_info'] = []
+            data = self._execute("PRAGMA table_info(%s);" % self.table)
+            for row in data:
+                col = {}
+                col['name'] = row['name']
+                col['type'] = row['type']
+                col['notnull'] = row['notnull']
+                col['dflt_value'] = row['dflt_value']
+                col['pk'] = row['pk']
+                metainfo['col_info'].append(col)
+
+        #data info
+        datainfo = []
+
+        if self.nohist:
+            sqlstmt = "SELECT T1.version, T1.pkgarch, T1.checksum, T1.value FROM %s as T1, \
+                    (SELECT version,pkgarch,max(value) as maxvalue FROM %s GROUP BY version,pkgarch) as T2 \
+                    WHERE T1.version=T2.version AND T1.pkgarch=T2.pkgarch AND T1.value=T2.maxvalue " % (self.table, self.table)
+        else:
+            sqlstmt = "SELECT * FROM %s as T1 WHERE 1=1 " % self.table
+        sqlarg = []
+        where = ""
+        if version:
+            where += "AND T1.version=? "
+            sqlarg.append(str(version))
+        if pkgarch:
+            where += "AND T1.pkgarch=? "
+            sqlarg.append(str(pkgarch))
+        if checksum:
+            where += "AND T1.checksum=? "
+            sqlarg.append(str(checksum))
+
+        sqlstmt += where + ";"
+
+        if len(sqlarg):
+            data = self._execute(sqlstmt, tuple(sqlarg))
+        else:
+            data = self._execute(sqlstmt)
+        for row in data:
+            if row['version']:
+                col = {}
+                col['version'] = row['version']
+                col['pkgarch'] = row['pkgarch']
+                col['checksum'] = row['checksum']
+                col['value'] = row['value']
+                datainfo.append(col)
+        return (metainfo, datainfo)
+
+class PRData(object):
+    """Object representing the PR database"""
+    def __init__(self, filename, nohist=True):
+        self.filename=os.path.abspath(filename)
+        self.nohist=nohist
+        #build directory hierarchy
+        try:
+            os.makedirs(os.path.dirname(self.filename))
+        except OSError as e:
+            if e.errno != errno.EEXIST:
+                raise e
+        self.connection=sqlite3.connect(self.filename, isolation_level="EXCLUSIVE", check_same_thread = False)
+        self.connection.row_factory=sqlite3.Row
+        self.connection.execute("pragma synchronous = off;")
+        self.connection.execute("PRAGMA journal_mode = WAL;")
+        self._tables={}
+
+    def __del__(self):
+        self.connection.close()
+
+    def __getitem__(self,tblname):
+        if not isinstance(tblname, basestring):
+            raise TypeError("tblname argument must be a string, not '%s'" %
+                            type(tblname))
+        if tblname in self._tables:
+            return self._tables[tblname]
+        else:
+            tableobj = self._tables[tblname] = PRTable(self.connection, tblname, self.nohist)
+            return tableobj
+
+    def __delitem__(self, tblname):
+        if tblname in self._tables:
+            del self._tables[tblname]
+        logger.info("drop table %s" % (tblname))
+        self.connection.execute("DROP TABLE IF EXISTS %s;" % tblname) 
diff --git a/bitbake/lib/prserv/serv.py b/bitbake/lib/prserv/serv.py
new file mode 100644
index 0000000..5c0ffb9
--- /dev/null
+++ b/bitbake/lib/prserv/serv.py
@@ -0,0 +1,418 @@
+import os,sys,logging
+import signal, time
+from SimpleXMLRPCServer import SimpleXMLRPCServer, SimpleXMLRPCRequestHandler
+import threading
+import Queue
+
+try:
+    import sqlite3
+except ImportError:
+    from pysqlite2 import dbapi2 as sqlite3
+
+import bb.server.xmlrpc
+import prserv
+import prserv.db
+import errno
+
+logger = logging.getLogger("BitBake.PRserv")
+
+if sys.hexversion < 0x020600F0:
+    print("Sorry, python 2.6 or later is required.")
+    sys.exit(1)
+
+class Handler(SimpleXMLRPCRequestHandler):
+    def _dispatch(self,method,params):
+        try:
+            value=self.server.funcs[method](*params)
+        except:
+            import traceback
+            traceback.print_exc()
+            raise
+        return value
+
+PIDPREFIX = "/tmp/PRServer_%s_%s.pid"
+singleton = None
+
+
+class PRServer(SimpleXMLRPCServer):
+    def __init__(self, dbfile, logfile, interface, daemon=True):
+        ''' constructor '''
+        import socket
+        try:
+            SimpleXMLRPCServer.__init__(self, interface,
+                                        logRequests=False, allow_none=True)
+        except socket.error:
+            ip=socket.gethostbyname(interface[0])
+            port=interface[1]
+            msg="PR Server unable to bind to %s:%s\n" % (ip, port)
+            sys.stderr.write(msg)
+            raise PRServiceConfigError
+
+        self.dbfile=dbfile
+        self.daemon=daemon
+        self.logfile=logfile
+        self.working_thread=None
+        self.host, self.port = self.socket.getsockname()
+        self.pidfile=PIDPREFIX % (self.host, self.port)
+
+        self.register_function(self.getPR, "getPR")
+        self.register_function(self.quit, "quit")
+        self.register_function(self.ping, "ping")
+        self.register_function(self.export, "export")
+        self.register_function(self.importone, "importone")
+        self.register_introspection_functions()
+
+        self.db = prserv.db.PRData(self.dbfile)
+        self.table = self.db["PRMAIN"]
+
+        self.requestqueue = Queue.Queue()
+        self.handlerthread = threading.Thread(target = self.process_request_thread)
+        self.handlerthread.daemon = False
+
+    def process_request_thread(self):
+        """Same as in BaseServer but as a thread.
+
+        In addition, exception handling is done here.
+
+        """
+        iter_count = 1
+        # 60 iterations between syncs or sync if dirty every ~30 seconds
+        iterations_between_sync = 60
+
+        while not self.quit:
+            try:
+                (request, client_address) = self.requestqueue.get(True, 30)
+            except Queue.Empty:
+                self.table.sync_if_dirty()
+                continue
+            try:
+                self.finish_request(request, client_address)
+                self.shutdown_request(request)
+                iter_count = (iter_count + 1) % iterations_between_sync
+                if iter_count == 0:
+                    self.table.sync_if_dirty()
+            except:
+                self.handle_error(request, client_address)
+                self.shutdown_request(request)
+                self.table.sync()
+            self.table.sync_if_dirty()
+
+    def sigint_handler(self, signum, stack):
+        self.table.sync()
+
+    def sigterm_handler(self, signum, stack):
+        self.table.sync()
+        raise SystemExit
+
+    def process_request(self, request, client_address):
+        self.requestqueue.put((request, client_address))
+
+    def export(self, version=None, pkgarch=None, checksum=None, colinfo=True):
+        try:
+            return self.table.export(version, pkgarch, checksum, colinfo)
+        except sqlite3.Error as exc:
+            logger.error(str(exc))
+            return None
+
+    def importone(self, version, pkgarch, checksum, value):
+        return self.table.importone(version, pkgarch, checksum, value)
+
+    def ping(self):
+        return not self.quit
+
+    def getinfo(self):
+        return (self.host, self.port)
+
+    def getPR(self, version, pkgarch, checksum):
+        try:
+            return self.table.getValue(version, pkgarch, checksum)
+        except prserv.NotFoundError:
+            logger.error("can not find value for (%s, %s)",version, checksum)
+            return None
+        except sqlite3.Error as exc:
+            logger.error(str(exc))
+            return None
+
+    def quit(self):
+        self.quit=True
+        return
+
+    def work_forever(self,):
+        self.quit = False
+        self.timeout = 0.5
+
+        logger.info("Started PRServer with DBfile: %s, IP: %s, PORT: %s, PID: %s" %
+                     (self.dbfile, self.host, self.port, str(os.getpid())))
+
+        self.handlerthread.start()
+        while not self.quit:
+            self.handle_request()
+        self.handlerthread.join()
+        self.table.sync()
+        logger.info("PRServer: stopping...")
+        self.server_close()
+        return
+
+    def start(self):
+        if self.daemon:
+            pid = self.daemonize()
+        else:
+            pid = self.fork()
+
+        # Ensure both the parent sees this and the child from the work_forever log entry above
+        logger.info("Started PRServer with DBfile: %s, IP: %s, PORT: %s, PID: %s" %
+                     (self.dbfile, self.host, self.port, str(pid)))
+
+    def delpid(self):
+        os.remove(self.pidfile)
+
+    def daemonize(self):
+        """
+        See Advanced Programming in the UNIX, Sec 13.3
+        """
+        try:
+            pid = os.fork()
+            if pid > 0:
+                os.waitpid(pid, 0)
+                #parent return instead of exit to give control 
+                return pid
+        except OSError as e:
+            raise Exception("%s [%d]" % (e.strerror, e.errno))
+
+        os.setsid()
+        """
+        fork again to make sure the daemon is not session leader, 
+        which prevents it from acquiring controlling terminal
+        """
+        try:
+            pid = os.fork()
+            if pid > 0: #parent
+                os._exit(0)
+        except OSError as e:
+            raise Exception("%s [%d]" % (e.strerror, e.errno))
+
+        self.cleanup_handles()
+        os._exit(0)
+
+    def fork(self):
+        try:
+            pid = os.fork()
+            if pid > 0:
+                return pid
+        except OSError as e:
+            raise Exception("%s [%d]" % (e.strerror, e.errno))
+
+        bb.utils.signal_on_parent_exit("SIGTERM")
+        self.cleanup_handles()
+        os._exit(0)
+
+    def cleanup_handles(self):
+        signal.signal(signal.SIGINT, self.sigint_handler)
+        signal.signal(signal.SIGTERM, self.sigterm_handler)
+        os.umask(0)
+        os.chdir("/")
+
+        sys.stdout.flush()
+        sys.stderr.flush()
+        si = file('/dev/null', 'r')
+        so = file(self.logfile, 'a+')
+        se = so
+        os.dup2(si.fileno(),sys.stdin.fileno())
+        os.dup2(so.fileno(),sys.stdout.fileno())
+        os.dup2(se.fileno(),sys.stderr.fileno())
+
+        # Clear out all log handlers prior to the fork() to avoid calling
+        # event handlers not part of the PRserver
+        for logger_iter in logging.Logger.manager.loggerDict.keys():
+            logging.getLogger(logger_iter).handlers = []
+
+        # Ensure logging makes it to the logfile
+        streamhandler = logging.StreamHandler()
+        streamhandler.setLevel(logging.DEBUG)
+        formatter = bb.msg.BBLogFormatter("%(levelname)s: %(message)s")
+        streamhandler.setFormatter(formatter)
+        logger.addHandler(streamhandler)
+
+        # write pidfile
+        pid = str(os.getpid()) 
+        pf = file(self.pidfile, 'w')
+        pf.write("%s\n" % pid)
+        pf.close()
+
+        self.work_forever()
+        self.delpid()
+
+class PRServSingleton(object):
+    def __init__(self, dbfile, logfile, interface):
+        self.dbfile = dbfile
+        self.logfile = logfile
+        self.interface = interface
+        self.host = None
+        self.port = None
+
+    def start(self):
+        self.prserv = PRServer(self.dbfile, self.logfile, self.interface, daemon=False)
+        self.prserv.start()
+        self.host, self.port = self.prserv.getinfo()
+
+    def getinfo(self):
+        return (self.host, self.port)
+
+class PRServerConnection(object):
+    def __init__(self, host, port):
+        if is_local_special(host, port):
+            host, port = singleton.getinfo()
+        self.host = host
+        self.port = port
+        self.connection, self.transport = bb.server.xmlrpc._create_server(self.host, self.port)
+
+    def terminate(self):
+        try:
+            logger.info("Terminating PRServer...")
+            self.connection.quit()
+        except Exception as exc:
+            sys.stderr.write("%s\n" % str(exc))
+
+    def getPR(self, version, pkgarch, checksum):
+        return self.connection.getPR(version, pkgarch, checksum)
+
+    def ping(self):
+        return self.connection.ping()
+
+    def export(self,version=None, pkgarch=None, checksum=None, colinfo=True):
+        return self.connection.export(version, pkgarch, checksum, colinfo)
+
+    def importone(self, version, pkgarch, checksum, value):
+        return self.connection.importone(version, pkgarch, checksum, value)
+
+    def getinfo(self):
+        return self.host, self.port
+
+def start_daemon(dbfile, host, port, logfile):
+    pidfile = PIDPREFIX % (host, port)
+    try:
+        pf = file(pidfile,'r')
+        pid = int(pf.readline().strip())
+        pf.close()
+    except IOError:
+        pid = None
+
+    if pid:
+        sys.stderr.write("pidfile %s already exist. Daemon already running?\n"
+                            % pidfile)
+        return 1
+
+    server = PRServer(os.path.abspath(dbfile), os.path.abspath(logfile), (host,port))
+    server.start()
+    return 0
+
+def stop_daemon(host, port):
+    pidfile = PIDPREFIX % (host, port)
+    try:
+        pf = file(pidfile,'r')
+        pid = int(pf.readline().strip())
+        pf.close()
+    except IOError:
+        pid = None
+
+    if not pid:
+        sys.stderr.write("pidfile %s does not exist. Daemon not running?\n"
+                        % pidfile)
+
+    try:
+        PRServerConnection(host, port).terminate()
+    except:
+        logger.critical("Stop PRService %s:%d failed" % (host,port))
+
+    try:
+        if pid:
+            wait_timeout = 0
+            print("Waiting for pr-server to exit.")
+            while is_running(pid) and wait_timeout < 50:
+                time.sleep(0.1)
+                wait_timeout += 1
+
+            if is_running(pid):
+                print("Sending SIGTERM to pr-server.")
+                os.kill(pid,signal.SIGTERM)
+                time.sleep(0.1)
+
+            if os.path.exists(pidfile):
+                os.remove(pidfile)
+
+    except OSError as e:
+        err = str(e)
+        if err.find("No such process") <= 0:
+            raise e
+
+    return 0
+
+def is_running(pid):
+    try:
+        os.kill(pid, 0)
+    except OSError as err:
+        if err.errno == errno.ESRCH:
+            return False
+    return True
+
+def is_local_special(host, port):
+    if host.strip().upper() == 'localhost'.upper() and (not port):
+        return True
+    else:
+        return False
+
+class PRServiceConfigError(Exception):
+    pass
+
+def auto_start(d):
+    global singleton
+
+    host_params = filter(None, (d.getVar('PRSERV_HOST', True) or '').split(':'))
+    if not host_params:
+        return None
+
+    if len(host_params) != 2:
+        logger.critical('\n'.join(['PRSERV_HOST: incorrect format',
+                'Usage: PRSERV_HOST = "<hostname>:<port>"']))
+        raise PRServiceConfigError
+
+    if is_local_special(host_params[0], int(host_params[1])) and not singleton:
+        import bb.utils
+        cachedir = (d.getVar("PERSISTENT_DIR", True) or d.getVar("CACHE", True))
+        if not cachedir:
+            logger.critical("Please set the 'PERSISTENT_DIR' or 'CACHE' variable")
+            raise PRServiceConfigError
+        bb.utils.mkdirhier(cachedir)
+        dbfile = os.path.join(cachedir, "prserv.sqlite3")
+        logfile = os.path.join(cachedir, "prserv.log")
+        singleton = PRServSingleton(os.path.abspath(dbfile), os.path.abspath(logfile), ("localhost",0))
+        singleton.start()
+    if singleton:
+        host, port = singleton.getinfo()
+    else:
+        host = host_params[0]
+        port = int(host_params[1])
+
+    try:
+        connection = PRServerConnection(host,port)
+        connection.ping()
+        realhost, realport = connection.getinfo()
+        return str(realhost) + ":" + str(realport)
+        
+    except Exception:
+        logger.critical("PRservice %s:%d not available" % (host, port))
+        raise PRServiceConfigError
+
+def auto_shutdown(d=None):
+    global singleton
+    if singleton:
+        host, port = singleton.getinfo()
+        try:
+            PRServerConnection(host, port).terminate()
+        except:
+            logger.critical("Stop PRService %s:%d failed" % (host,port))
+        singleton = None
+
+def ping(host, port):
+    conn=PRServerConnection(host, port)
+    return conn.ping()