Python Interest.setChildSelector方法代码示例

# 需要导入模块: from pyndn import Interest [as 别名]
# 或者: from pyndn.Interest import setChildSelector [as 别名]
def main():
    interest = Interest()
    interest.wireDecode(TlvInterest)
    dump("Interest:")
    dumpInterest(interest)
    
    encoding = interest.wireEncode()
    dump("")
    dump("Re-encoded interest", encoding.toHex())
    
    reDecodedInterest = Interest()
    reDecodedInterest.wireDecode(encoding)
    dump("Re-decoded Interest:")
    dumpInterest(reDecodedInterest)

    freshInterest = Interest(Name("/ndn/abc"))
    freshInterest.setMustBeFresh(False)
    dump(freshInterest.toUri())
    freshInterest.setMinSuffixComponents(4)
    freshInterest.setMaxSuffixComponents(6)
    freshInterest.getKeyLocator().setType(KeyLocatorType.KEY_LOCATOR_DIGEST)
    freshInterest.getKeyLocator().setKeyData(bytearray(
      [0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0A, 0x0B, 0x0C, 0x0D, 0x0E, 0x0F, 
       0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1A, 0x1B, 0x1C, 0x1D, 0x1E, 0x1F]))
    freshInterest.getExclude().appendComponent(Name("abc")[0]).appendAny()
    freshInterest.setInterestLifetimeMilliseconds(30000)
    freshInterest.setChildSelector(1)
    freshInterest.setMustBeFresh(True);
    freshInterest.setScope(2)

    reDecodedFreshInterest = Interest()
    reDecodedFreshInterest.wireDecode(freshInterest.wireEncode())
    dump("")
    dump("Re-decoded fresh Interest:")
    dumpInterest(reDecodedFreshInterest)

# 需要导入模块: from pyndn import Interest [as 别名]
# 或者: from pyndn.Interest import setChildSelector [as 别名]
def main():
    # The default Face will connect using a Unix socket, or to "localhost".
    face = Face()
    keyChain = KeyChain()
    face.setCommandSigningInfo(keyChain, keyChain.getDefaultCertificateName())

    dataPrefix = "/home/test1/data"
    repoDataPrefix = "/home/test1/data"
    # Set up repo-ng, register prefix for repo-ng's fetch prefix
    # Per configuration file in /usr/local/etc/ndn/repo-ng.conf
    # memCache is not used for now; repo is hoping that the piece of data in question is still being held at nfd
    #memCache = MemoryContentCache(face, 100000)
    #memCache.registerPrefix(Name(repoDataPrefix), onRegisterFailed, onDataNotFound)

    counter = Counter(face, repoDataPrefix)

    interest = Interest(Name(dataPrefix))
    interest.setChildSelector(1)
    interest.setInterestLifetimeMilliseconds(defaultInterestLifetime)
    face.expressInterest(interest, counter.onData, counter.onTimeout)
    
    while True:
        face.processEvents()
        # We need to sleep for a few milliseconds so we don't use 100% of the CPU.
        time.sleep(1)
    face.shutdown()

# 需要导入模块: from pyndn import Interest [as 别名]
# 或者: from pyndn.Interest import setChildSelector [as 别名]
 def reissueInterest(self):
     BACKOFF_THRESHOLD = 10
     if self.backoffCounter > BACKOFF_THRESHOLD:
         self.TIMEOUT += 50
         self.backoffCounter = 0
         self.logger.debug('Backing off interval to ' + str(self.TIMEOUT))
     if self.backoffCounter < -BACKOFF_THRESHOLD:
         self.TIMEOUT -= 50
         self.backoffCounter = 0
         self.logger.debug('Reducing backoff interval to ' + str(self.TIMEOUT))
     if self.nextIssue is not None:
         now = time.clock()
         if self.nextIssue > now:
             pass
            # time.sleep(self.nextIssue-now)
     interest = Interest(Name(self.prefix))
     interest.setInterestLifetimeMilliseconds(self.interestLifetime)
     interest.setMustBeFresh(False)
     if self.lastVersion is not None:
         e = Exclude()
         e.appendAny()
         e.appendComponent(self.lastVersion)
         interest.setExclude(e)
     interest.setChildSelector(1) #rightmost == freshest
     self.face.expressInterest(interest, self.onData, self.onTimeout)
     self.nextIssue = time.clock()+self.TIMEOUT/2000

# 需要导入模块: from pyndn import Interest [as 别名]
# 或者: from pyndn.Interest import setChildSelector [as 别名]
    def startTrustSchemaUpdate(self, appPrefix, onUpdateSuccess = None, onUpdateFailed = None):
        """
        Starts trust schema update for under an application prefix: initial 
        interest asks for the rightMostChild, and later interests are sent 
        with previous version excluded. Each verified trust schema will trigger
        onUpdateSuccess and update the ConfigPolicyManager for the keyChain
        in this instance, and unverified ones will trigger onUpdateFailed.

        The keyChain and trust anchor should be set up using setupDefaultIdentityAndRoot
        before calling this method. 

        :param appPrefix: the prefix to ask trust schema for. (interest name: /<prefix>/_schema)
        :type appPrefix: Name
        :param onUpdateSuccess: (optional) onUpdateSuccess(trustSchemaStr, isInitial) is 
          called when update succeeds
        :type onUpdateSuccess: function object
        :param onUpdateFailed: (optional) onUpdateFailed(msg) is called when update fails
        :type onUpdateFailed: function object
        """
        namespace = appPrefix.toUri()
        if namespace in self._trustSchemas:
            if self._trustSchemas[namespace]["following"] == True:
                print "Already following trust schema under this namespace!"
                return
            self._trustSchemas[namespace]["following"] = True
        else:
            self._trustSchemas[namespace] = {"following": True, "version": 0, "is-initial": True}

        initialInterest = Interest(Name(namespace).append("_schema"))
        initialInterest.setChildSelector(1)
        self._face.expressInterest(initialInterest, 
          lambda interest, data: self.onTrustSchemaData(interest, data, onUpdateSuccess, onUpdateFailed), 
          lambda interest: self.onTrustSchemaTimeout(interest, onUpdateSuccess, onUpdateFailed))
        return

# 需要导入模块: from pyndn import Interest [as 别名]
# 或者: from pyndn.Interest import setChildSelector [as 别名]
    def startPublishingAggregation(self, params, childrenList, dataType, aggregationType):
        if __debug__:
            print('Start publishing for ' + dataType + '-' + aggregationType)
        
        # aggregation calculating and publishing mechanism
        publishingPrefix = Name(self._identityName).append(DATA_COMPONENT).append(dataType).append(AGGREGATION_COMPONENT).append(aggregationType)
        self._dataQueue[dataType + aggregationType] = DataQueue(params, childrenList, publishingPrefix)

        if len(childrenList.keys()) == 0:
            # TODO: make start_time optional for leaf nodes
            self._loop.call_later(int(params['producer_interval']), self.calculateAggregation, dataType, aggregationType, childrenList, int(params['start_time']), int(params['producer_interval']), publishingPrefix, True)
        else:
            # express interest for children who produce the same data and aggregation type
            for childName in childrenList.keys():
                name = Name(self._identityName).append(childName).append(DATA_COMPONENT).append(dataType).append(AGGREGATION_COMPONENT).append(aggregationType)
                interest = Interest(name)
                # if start_time is specified, we ask for data starting at start_time; 
                # if not, we ask for the right most child and go from there
                if ('start_time' in childrenList[childName]):
                    endTime = int(childrenList[childName]['start_time']) + int(childrenList[childName]['producer_interval'])
                    interest.getName().append(str(childrenList[childName]['start_time'])).append(str(endTime))
                else:
                    # TODO: For now we are playing with historical data, for each run we don't want to miss any data, thus we start with leftMost
                    interest.setChildSelector(0)
                    interest.setMustBeFresh(True)
                interest.setInterestLifetimeMilliseconds(DEFAULT_INTEREST_LIFETIME)
                if __debug__:
                    print('  Issue interest: ' + interest.getName().toUri())
                self._face.expressInterest(interest, self.onData, self.onTimeout)

        return

# 需要导入模块: from pyndn import Interest [as 别名]
# 或者: from pyndn.Interest import setChildSelector [as 别名]
def main():
    interest = Interest()
    interest.wireDecode(TlvInterest)
    dump("Interest:")
    dumpInterest(interest)

    # Set the name again to clear the cached encoding so we encode again.
    interest.setName(interest.getName())
    encoding = interest.wireEncode()
    dump("")
    dump("Re-encoded interest", encoding.toHex())

    reDecodedInterest = Interest()
    reDecodedInterest.wireDecode(encoding)
    dump("Re-decoded Interest:")
    dumpInterest(reDecodedInterest)

    freshInterest = Interest(Name("/ndn/abc"))
    freshInterest.setMustBeFresh(False)
    dump(freshInterest.toUri())
    freshInterest.setMinSuffixComponents(4)
    freshInterest.setMaxSuffixComponents(6)
    freshInterest.getKeyLocator().setType(KeyLocatorType.KEY_LOCATOR_DIGEST)
    freshInterest.getKeyLocator().setKeyData(bytearray(
      [0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0A, 0x0B, 0x0C, 0x0D, 0x0E, 0x0F,
       0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1A, 0x1B, 0x1C, 0x1D, 0x1E, 0x1F]))
    freshInterest.getExclude().appendComponent(Name("abc")[0]).appendAny()
    freshInterest.setInterestLifetimeMilliseconds(30000)
    freshInterest.setChildSelector(1)
    freshInterest.setMustBeFresh(True);
    freshInterest.setScope(2)

    identityStorage = MemoryIdentityStorage()
    privateKeyStorage = MemoryPrivateKeyStorage()
    keyChain = KeyChain(IdentityManager(identityStorage, privateKeyStorage),
                        SelfVerifyPolicyManager(identityStorage))

    # Initialize the storage.
    keyName = Name("/testname/DSK-123")
    certificateName = keyName.getSubName(0, keyName.size() - 1).append(
      "KEY").append(keyName[-1]).append("ID-CERT").append("0")
    identityStorage.addKey(keyName, KeyType.RSA, Blob(DEFAULT_RSA_PUBLIC_KEY_DER))
    privateKeyStorage.setKeyPairForKeyName(
      keyName, KeyType.RSA, DEFAULT_RSA_PUBLIC_KEY_DER, DEFAULT_RSA_PRIVATE_KEY_DER)

    # Make a Face just so that we can sign the interest.
    face = Face("localhost")
    face.setCommandSigningInfo(keyChain, certificateName)
    face.makeCommandInterest(freshInterest)

    reDecodedFreshInterest = Interest()
    reDecodedFreshInterest.wireDecode(freshInterest.wireEncode())
    dump("")
    dump("Re-decoded fresh Interest:")
    dumpInterest(reDecodedFreshInterest)

    keyChain.verifyInterest(
      reDecodedFreshInterest, makeOnVerified("Freshly-signed Interest"),
      makeOnVerifyFailed("Freshly-signed Interest"))

# 需要导入模块: from pyndn import Interest [as 别名]
# 或者: from pyndn.Interest import setChildSelector [as 别名]
def createFreshInterest():
    freshInterest = Interest(Name("/ndn/abc"))
    freshInterest.setMustBeFresh(False)
    freshInterest.setMinSuffixComponents(4)
    freshInterest.setMaxSuffixComponents(6)
    freshInterest.getKeyLocator().setType(KeyLocatorType.KEY_LOCATOR_DIGEST)
    freshInterest.getKeyLocator().setKeyData(bytearray(
      [0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0A, 0x0B, 0x0C, 0x0D, 0x0E, 0x0F, 
       0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1A, 0x1B, 0x1C, 0x1D, 0x1E, 0x1F]))
    freshInterest.getExclude().appendComponent(Name("abc")[0]).appendAny()
    freshInterest.setInterestLifetimeMilliseconds(30000)
    freshInterest.setChildSelector(1)
    freshInterest.setMustBeFresh(True);
    freshInterest.setScope(2)

    return freshInterest

# 需要导入模块: from pyndn import Interest [as 别名]
# 或者: from pyndn.Interest import setChildSelector [as 别名]
    def onData(self, interest, data):
        self._keyChain.verifyData(data, self.onVerified, self.onVerifyFailed)

        dataName = data.getName()
        dataQueue = None

        if __debug__:
            print("Got data: " + dataName.toUri() + "; " + data.getContent().toRawStr())
        for i in range(0, len(dataName)):
            if dataName.get(i).toEscapedString() == AGGREGATION_COMPONENT:
                dataType = dataName.get(i - 1).toEscapedString()
                aggregationType = dataName.get(i + 1).toEscapedString()
                
                startTime = int(dataName.get(i + 2).toEscapedString())
                endTime = int(dataName.get(i + 3).toEscapedString())
                childName = dataName.get(i - 3).toEscapedString()

                dataAndAggregationType = dataType + aggregationType
                
                dataDictKey = self.getDataDictKey(startTime, endTime, childName)
                dataQueue = self._dataQueue[dataAndAggregationType]
                dataQueue._dataDict[dataDictKey] = data
                break

        # TODO: check what if interval/starttime is misconfigured
        if dataQueue:
            self.calculateAggregation(dataType, aggregationType, dataQueue._childrenList, startTime, endTime - startTime, dataQueue._publishingPrefix)

        # Always ask for the next piece of data when we receive this one; assumes interval does not change; this also assumes there are no more components after endTime
        #newInterestName = dataName.getPrefix(i + 2).append(str(endTime)).append(str(endTime + (endTime - startTime)))
        
        # We don't expect aggregated data name to be continuous within our given time window, so we ask with exclusion instead
        newInterestName = dataName.getPrefix(i + 2)
        newInterest = Interest(interest)
        newInterest.setName(newInterestName)
        newInterest.setChildSelector(0)

        exclude = Exclude()
        exclude.appendAny()
        exclude.appendComponent(dataName.get(i + 2))
        newInterest.setExclude(exclude)

        self._face.expressInterest(newInterest, self.onData, self.onTimeout)
        if __debug__:
            print("  issue interest: " + interest.getName().toUri())

        return

# 需要导入模块: from pyndn import Interest [as 别名]
# 或者: from pyndn.Interest import setChildSelector [as 别名]
 def expressInterest(self):
     try:
         interestName = input('Interest name: ')
         if len(interestName):
             toSign = input('Signed? (y/N): ').upper().startswith('Y')
             interest = Interest(Name(interestName))
             interest.setInterestLifetimeMilliseconds(5000)
             interest.setChildSelector(1)
             if (toSign):
                 self.face.makeCommandInterest(interest) 
             self.face.expressInterest(interest, self.onDataReceived, self.onInterestTimeout)
         else:
             print("Aborted")
     except KeyboardInterrupt:
             print("Aborted")
     finally:
             self.loop.call_soon(self.displayMenu)

# 需要导入模块: from pyndn import Interest [as 别名]
# 或者: from pyndn.Interest import setChildSelector [as 别名]
    def onSchemaVerified(self, data, onUpdateSuccess, onUpdateFailed):
        print "trust schema verified: " + data.getName().toUri()
        version = data.getName().get(-1)
        namespace = data.getName().getPrefix(-2).toUri()
        if not (namespace in self._trustSchemas):
            print "unexpected: received trust schema for application namespace that's not being followed; malformed data name?"
            return

        if version.toVersion() <= self._trustSchemas[namespace]["version"]:
            msg = "Got out-of-date trust schema"
            print msg
            if onUpdateFailed:
                onUpdateFailed(msg)
            return

        self._trustSchemas[namespace]["version"] = version.toVersion()
        
        if "pending-schema" in self._trustSchemas[namespace] and self._trustSchemas[namespace]["pending-schema"].getName().toUri() == data.getName().toUri():
            # we verified a pending trust schema, don't need to keep that any more
            del self._trustSchemas[namespace]["pending-schema"]

        self._trustSchemas[namespace]["trust-schema"] = data.getContent().toRawStr()
        print self._trustSchemas[namespace]["trust-schema"]

        # TODO: what about trust schema for discovery, is discovery its own application?
        newInterest = Interest(Name(data.getName()).getPrefix(-1))
        newInterest.setChildSelector(1)
        exclude = Exclude()
        exclude.appendAny()
        exclude.appendComponent(version)
        newInterest.setExclude(exclude)
        self._face.expressInterest(newInterest, 
          lambda interest, data: self.onTrustSchemaData(interest, data, onUpdateSuccess, onUpdateFailed), 
          lambda interest: self.onTrustSchemaTimeout(interest, onUpdateSuccess, onUpdateFailed))

        # Note: this changes the verification rules for root cert, future trust schemas as well; ideally from the outside this doesn't have an impact, but do we want to avoid this?
        # Per reset function in ConfigPolicyManager; For now we don't call reset as we still want root cert in our certCache, instead of asking for it again (when we want to verify) each time we update the trust schema
        self._policyManager.config = BoostInfoParser()
        self._policyManager.config.read(self._trustSchemas[namespace]["trust-schema"], "updated-schema")
        
        if onUpdateSuccess:
            onUpdateSuccess(data.getContent().toRawStr(), self._trustSchemas[namespace]["is-initial"])
        self._trustSchemas[namespace]["is-initial"] = False
        return

# 需要导入模块: from pyndn import Interest [as 别名]
# 或者: from pyndn.Interest import setChildSelector [as 别名]
    def expressInterestPirAndRepeat(self):
        self.log.debug("callbackCountUniqueData: " + str(self._callbackCountUniqueData) + ", callbackCountTimeout: " + str(self._callbackCountTimeout))

        # Express interest for each pir we have discovered
        for pir in self.getPirs():
            interest = Interest(Name(pir.id))
            interest.setExclude(pir.status.getExclude())
            interest.setInterestLifetimeMilliseconds(1000.0)
            interest.setChildSelector(1)

            self.face.expressInterest(interest, self.onDataPir, self.onTimeoutPir)
            self._countExpressedInterests += 1
            debugStr = "Sent interest: " + interest.getName().toUri()
            debugStr += "\tExclude: " + interest.getExclude().toUri()
            debugStr += "\tLifetime: " + str(interest.getInterestLifetimeMilliseconds())
 
            self.log.debug(debugStr)
        # Reschedule again in 0.5 sec
        self.loop.call_later(1.0, self.expressInterestPirAndRepeat)

# 需要导入模块: from pyndn import Interest [as 别名]
# 或者: from pyndn.Interest import setChildSelector [as 别名]
 def onSchemaVerificationFailed(self, data, reason, onUpdateSuccess, onUpdateFailed):
     print "trust schema verification failed: " + reason
     namespace = data.getName().getPrefix(-2).toUri()
     if not (namespace in self._trustSchemas):
         print "unexpected: received trust schema for application namespace that's not being followed; malformed data name?"
         return
     
     newInterest = Interest(Name(data.getName()).getPrefix(-1))
     newInterest.setChildSelector(1)
     exclude = Exclude()
     exclude.appendAny()
     exclude.appendComponent(Name.Component.fromVersion(self._trustSchemas[namespace]["version"]))
     newInterest.setExclude(exclude)
     # Don't immediately ask for potentially the same content again if verification fails
     self._face.callLater(4000, lambda : 
       self._face.expressInterest(newInterest, 
         lambda interest, data: self.onTrustSchemaData(interest, data, onUpdateSuccess, onUpdateFailed), 
         lambda interest: self.onTrustSchemaTimeout(interest, onUpdateSuccess, onUpdateFailed)))
     return

# 需要导入模块: from pyndn import Interest [as 别名]
# 或者: from pyndn.Interest import setChildSelector [as 别名]
    def handleCommandInterests(self, prefix, interest, transport, prefixId):
        # TODO: verification
        interestName = interest.getName()
        if len(interestName) <= len(prefix)+4:
            self.log.info("Bad command interest")
        commandName = str(interestName[len(prefix)].getValue())
        responseMessage =  RepoCommandResponseMessage()
        if commandName == 'insert':
            commandParams = interestName[len(prefix)+1].getValue()
            commandMessage = RepoCommandParameterMessage()
            ProtobufTlv.decode(commandMessage, commandParams)
            dataName = Name()
            fullSchemaName = Name()
            for component in commandMessage.command.name.components:
                fullSchemaName.append(component)
                if component == '_':
                    continue
                dataName.append(component)
            self.log.info("Insert request for {}".format(dataName))
            responseMessage.response.status_code = 100
            processId = self.currentProcessId
            self.currentProcessId += 1
            responseMessage.response.process_id = processId
        else:
            responseMessage.response.status_code = 403
        responseData = Data(interestName)
        responseData.setContent(ProtobufTlv.encode(responseMessage))
        transport.send(responseData.wireEncode().buf())

        # now send the interest out to the publisher
        # TODO: pendingProcesses becomes list of all processes as objects
        i = Interest(dataName)
        i.setChildSelector(1)
        i.setInterestLifetimeMilliseconds(4000)
        try:
            self.pendingProcesses[processId] = (dataName, 100)
        except NameError:
            pass # wasn't valid insert request
        else:
            self._insertFace.expressInterest(i, 
                    self._onInsertionDataReceived,
                    self._onInsertionDataTimeout)

# 需要导入模块: from pyndn import Interest [as 别名]
# 或者: from pyndn.Interest import setChildSelector [as 别名]
 def _expressCustomInterest(self, interestName):
     # TODO: make this a form, add timeout field
     try:
         handled = False
         (returnCode, returnStr) = self.ui.prompt(
             "Send interest",
             interestName,
             preExtra=["--extra-button", "--extra-label", "Signed", "--ok-label", "Unsigned"],
         )
         if returnCode == Dialog.DIALOG_ESC or returnCode == Dialog.DIALOG_CANCEL:
             self.loop.call_soon(self.expressInterest)
         else:
             interestName = Name(returnStr)
             doSigned = returnCode == Dialog.DIALOG_EXTRA
             interest = Interest(interestName)
             interest.setInterestLifetimeMilliseconds(5000)
             interest.setChildSelector(1)
             interest.setMustBeFresh(True)
             if doSigned:
                 self.face.makeCommandInterest(interest)
             self.ui.alert("Waiting for response to {}".format(interestName.toUri()), False)
             self.face.expressInterest(interest, self.onDataReceived, self.onInterestTimeout)
     except:
         self.loop.call_soon(self.expressInterest)

# 需要导入模块: from pyndn import Interest [as 别名]
# 或者: from pyndn.Interest import setChildSelector [as 别名]
    def _onContentSet(self, namespace, contentNamespace, callbackId):
        if not (len(contentNamespace.name) >= len(self._namespace.name) + 1 and
                contentNamespace.name[len(self._namespace.name)].isSegment()):
            # Not a segment, ignore.
            # Debug: If this is the first call, we still need to request segments.
            return

        # TODO: Use the Namspace mechanism to validate the Data packet.

        metaInfo = contentNamespace.data.metaInfo
        if (metaInfo.getFinalBlockId().getValue().size() > 0 and
             metaInfo.getFinalBlockId().isSegment()):
            self._finalSegmentNumber = metaInfo.getFinalBlockId().toSegment()

        # Retrieve as many segments as possible from the store.
        while True:
            nextSegmentNumber = self._maxRetrievedSegmentNumber + 1
            nextSegment = self.debugGetRightmostLeaf(
              self._namespace[Name.Component.fromSegment(nextSegmentNumber)])
            if nextSegment.content == None:
                break

            self._maxRetrievedSegmentNumber = nextSegmentNumber
            self._fireOnSegment(nextSegment)

            if (self._finalSegmentNumber != None and
                nextSegmentNumber == self._finalSegmentNumber):
                # Finished.
                self._fireOnSegment(None)
                return

        if self._finalSegmentNumber == None and not self._didRequestFinalSegment:
            self._didRequestFinalSegment = True
            # Try to determine the final segment now.
            interestTemplate = Interest()
            interestTemplate.setInterestLifetimeMilliseconds(4000)
            interestTemplate.setChildSelector(1)
            self._namespace.expressInterest(interestTemplate)

        # Request new segments.
        childComponents = self._namespace.getChildComponents()
        # First, count how many are already requested and not received.
        nRequestedSegments = 0
        for component in childComponents:
            if not component.isSegment():
                # The namespace contains a child other than a segment. Ignore.
                continue

            child = self._namespace[component]
            # Debug: Check the leaf for content, but use the immediate child
            # for _debugSegmentStreamDidExpressInterest.
            if (self.debugGetRightmostLeaf(child).content == None and
                  hasattr(child, '_debugSegmentStreamDidExpressInterest') and
                  child._debugSegmentStreamDidExpressInterest):
                nRequestedSegments += 1
                if nRequestedSegments >= self._interestPipelineSize:
                    # Already maxed out on requests.
                    break

        # Now find unrequested segment numbers and request.
        segmentNumber = self._maxRetrievedSegmentNumber
        while nRequestedSegments < self._interestPipelineSize:
            segmentNumber += 1
            if (self._finalSegmentNumber != None and
                segmentNumber > self._finalSegmentNumber):
                break

            segment = self._namespace[Name.Component.fromSegment(segmentNumber)]
            if (self.debugGetRightmostLeaf(segment).content != None or
                (hasattr(segment, '_debugSegmentStreamDidExpressInterest') and
                  segment._debugSegmentStreamDidExpressInterest)):
                # Already got the data packet or already requested.
                continue

            nRequestedSegments += 1
            segment._debugSegmentStreamDidExpressInterest = True
            segment.expressInterest()