diff options
Diffstat (limited to 'libccnx-transport-rta/ccnx/transport/transport_rta/components/Flowcontrol_Vegas/vegas_Session.c')
| -rw-r--r-- | libccnx-transport-rta/ccnx/transport/transport_rta/components/Flowcontrol_Vegas/vegas_Session.c | 1379 |
1 files changed, 1379 insertions, 0 deletions
diff --git a/libccnx-transport-rta/ccnx/transport/transport_rta/components/Flowcontrol_Vegas/vegas_Session.c b/libccnx-transport-rta/ccnx/transport/transport_rta/components/Flowcontrol_Vegas/vegas_Session.c new file mode 100644 index 00000000..a77adc34 --- /dev/null +++ b/libccnx-transport-rta/ccnx/transport/transport_rta/components/Flowcontrol_Vegas/vegas_Session.c @@ -0,0 +1,1379 @@ +/* + * Copyright (c) 2017 Cisco and/or its affiliates. + * Licensed under the Apache License, Version 2.0 (the "License"); + * you may not use this file except in compliance with the License. + * You may obtain a copy of the License at: + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ + +/** + * See additional comments in component_Vegas.c + * + * Flow Control Algorithm + * ========================= + * Based on TCP Vegas. Please read the Vegas paper. We use similar + * variable names to the paper. Code looks quite a bit like the linux + * tcp_vegas.c too. + * + * Here's the differences. In CCN, an Interest is like an ACK token, it + * gives the network permission to send. The node issuing Interests needs + * to pace them to not exceed the network capacity. This is done by + * observing the delay of Content Objects. If the delay grows too quickly, + * then we back off linearly. If the delay is not much above what we expected + * based on the minimum observed delay, we increase linearly. + * + * During slow start, the interest window (still called "cwnd") doubles + * every other RTT until we exceed the slow_start_threshold or the delay + * increases too much. + * + * The RTT is calculated every RTT based on the observed minimum RTT during + * the previous period. + * + * We use RFC6298 Retransmission Timeout (RTO) calculation methods per + * flow control session (object basename). + * + * Just to be clear, there are two timers working. The RTO timer is for + * retransmitting interests if the flow as stalled out. The Vegas RTT + * calculation is for congestion window calculations. + * + * We we receive an out-of-order content object, we'll check the earlier + * segments to see if they have passed the Vegas RTT. If so, we'll + * re-express the interests. + * + * Each time we re-express an Interest, we might decrese the congestion + * window. If the last time the interest was sent was more recent than + * the last time we decreased the congestion window, we'll decrease the + * congestion window. If the last expression of the interest was before + * the most recent window decrease, the window is left alone. This means + * we'll only decreae the window once per re-expression. + */ + +#include <config.h> +#include <stdio.h> +#include <string.h> +#include <unistd.h> +#include <fcntl.h> +#include <sys/socket.h> +#include <limits.h> +#include <sys/queue.h> + +#define __STDC_FORMAT_MACROS +#include <inttypes.h> + +#include <LongBow/runtime.h> + +#include <parc/algol/parc_Memory.h> +#include <parc/algol/parc_SafeMemory.h> + +#include <parc/algol/parc_EventTimer.h> + +#include <ccnx/common/ccnx_NameSegmentNumber.h> +#include <ccnx/common/ccnx_WireFormatMessage.h> + +#include <ccnx/transport/common/transport_Message.h> +#include <ccnx/transport/transport_rta/core/rta_Framework.h> +#include <ccnx/transport/transport_rta/core/rta_Framework_Services.h> +#include <ccnx/transport/transport_rta/core/rta_ProtocolStack.h> +#include <ccnx/transport/transport_rta/core/rta_Connection.h> +#include <ccnx/transport/transport_rta/core/rta_Component.h> +#include <ccnx/transport/transport_rta/components/component_Flowcontrol.h> +#include "vegas_private.h" + +#include <ccnx/transport/test_tools/traffic_tools.h> + +#include <ccnx/common/internal/ccnx_InterestDefault.h> + +#include <ccnx/common/codec/schema_v1/ccnxCodecSchemaV1_TlvDictionary.h> + + +#define USE_MIN_BASE_RTT 0 + + +// initial congestion window of 2 interests +#define FC_INIT_CWND 2 + +// maximum cwnd (at 8KB/object, makes this 128 MB) +#define FC_MAX_CWND 16384 + +#define FC_MAX_SSTHRESH FC_MAX_CWND + +// initial RTT in msec (100 msec) +#define FC_INIT_RTT_MSEC 100 + +// initial RTO in msec +#define FC_INIT_RTO_MSEC 1000 + +#define FC_MSS 8704 +#define min(a, b) ((a < b) ? a : b) +#define max(a, b) ((a > b) ? a : b) + +// =========================================================== +struct vegas_connection_state; + +struct fc_window_entry { + bool valid; + ticks t; + ticks t_first_request; + segnum_t segnum; + + // set to true on the first interest request for + // the segment, false on subsequent requests + // Needed for Karn's algorithm on RTT sampling for RTO + bool first_request; + + // Content Object read + TransportMessage *transport_msg; +}; + +struct vegas_session { + RtaConnection *parent_connection; + RtaFramework *parent_framework; + VegasConnectionState *parent_fc; + + // next sampling time + ticks next_rtt_sample; + + // minimum observed RTT + int64_t base_RTT; // absolute minimum observed + int64_t min_RTT; // minimum RTT in current sample + int cnt_RTT; // number of RTTs seen in current sample + int64_t sum_RTT; // sum of RTTs + int slow_start_threshold; + + // the currently observed RTT + ticks current_rtt; + + // we do one detailed sample per RTT + bool sample_in_progress; + ticks sample_start; + uint64_t sample_segnum; + uint64_t sample_bytes_recevied; + + // Only adjust the cwnd every 2 RTTs. This + // indicates if we should adjust the RTT at the + // end of this sampling period + int do_fc_this_rtt; + + // circular buffer for segments + // tail - head (mod FC_MAX_CWND) is how may outstanding interests + // are in-flight. If the cwnd has been reduced, it could be larger + // than current_cwnd. + uint64_t starting_segnum; // segnum of the head + int window_head; // window index to read from + int window_tail; // window index to insert at + + uint32_t current_cwnd; + ticks last_cwnd_adjust; + + uint64_t final_segnum; // if we know the final block ID + + struct fc_window_entry window[FC_MAX_CWND]; + + PARCEventTimer *tick_event; + + // we will generate Interests with the same version as was received to start the session. + // Will also use the same lifetime settings as the original Interest. + + CCNxInterestInterface *interestInterface; + uint32_t lifetime; + PARCBuffer *keyIdRestriction; + CCNxName *basename; + uint64_t name_hash; + + uint64_t cnt_old_segments; + uint64_t cnt_fast_reexpress; + + // These are for RTO calculation + ticks SRTT; + ticks RTTVAR; + ticks RTO; + ticks next_rto; // when the next timer expires + + PARCLogLevel logLevel; +}; + +// Control parameters, measured in segments (tcp) or objects (ccn) +static int alpha = 2; +static int beta = 32; +static int _gamma = 1; + +// =========================================================== + + + +static void vegasSession_ExpressInterests(VegasSession *session); +static int vegasSession_ExpressInterestForEntry(VegasSession *session, struct fc_window_entry *entry); + +static void vegasSession_FastReexpress(VegasSession *session, struct fc_window_entry *ack_entry); +static void vegasSession_ForwardObjectsInOrder(VegasSession *session); + +static int vegasSession_GetSegnumFromObject(CCNxTlvDictionary *contentObjectDictionary, uint64_t *segnum); +static struct fc_window_entry * +vegasSession_GetWindowEntry(VegasSession *session, TransportMessage *tm, uint64_t segnum); + +static void vegasSession_ReleaseWindowEntry(struct fc_window_entry *entry); +static void vegasSession_RunAlgorithmOnReceive(VegasSession *session, struct fc_window_entry *entry); + +static void vegasSession_SetTimer(VegasSession *session, ticks tick_delay); +static void vegasSession_SlowReexpress(VegasSession *session); + +// ======================================================================= + + +static struct fc_window_entry * +vegasSession_GetWindowEntry(VegasSession *session, TransportMessage *tm, uint64_t segnum) +{ + int offset; + struct fc_window_entry *entry; + + offset = ((segnum - session->starting_segnum) + session->window_head) % FC_MAX_CWND; + entry = &session->window[offset]; + + assertTrue(entry->valid, "Requesting window entry for invalid entry %p", (void *) entry); + assertTrue(segnum == entry->segnum, "Expected seqnum not equal to window entry, expected %" PRIu64 ", got %" PRIu64, segnum, entry->segnum); + + if (entry->transport_msg != NULL) { + if (rtaLogger_IsLoggable(rtaFramework_GetLogger(session->parent_framework), RtaLoggerFacility_Flowcontrol, PARCLogLevel_Info)) { + rtaLogger_Log(rtaFramework_GetLogger(session->parent_framework), RtaLoggerFacility_Flowcontrol, PARCLogLevel_Info, __func__, + "session %p duplicate segment %" PRIu64 "", (void *) session, entry->segnum); + } + + transportMessage_Destroy(&entry->transport_msg); + } + + // store the content object + entry->transport_msg = tm; + + return entry; +} + +static int +vegasSession_GetSegnumFromObject(CCNxTlvDictionary *contentObjectDictionary, uint64_t *segnum) +{ + CCNxName *name = ccnxContentObject_GetName(contentObjectDictionary); + assertNotNull(name, "Content Object has null name") + { + ccnxTlvDictionary_Display(contentObjectDictionary, 0); + } + + bool success = trafficTools_GetObjectSegmentFromName(name, segnum); + + if (success) { + return 0; + } + return -1; +} + +static void +vegasSession_ReduceCongestionWindow(VegasSession *session) +{ + if (session->current_cwnd <= session->slow_start_threshold) { + // 3/4 it + session->current_cwnd = session->current_cwnd / 2 + session->current_cwnd / 4; + } else { + // in linear mode + session->current_cwnd--; + } + + if (session->current_cwnd < 2) { + session->current_cwnd = 2; + } + + session->last_cwnd_adjust = rtaFramework_GetTicks(session->parent_framework); +} + +static void +vegasSession_RunAlgorithmOnReceive(VegasSession *session, struct fc_window_entry *entry) +{ + ticks now; + int64_t fc_rtt; + + now = rtaFramework_GetTicks(session->parent_framework); + + // perform statistics updates. + + // If the codec did not include the raw message, we cannot increment the bytes counter + PARCBuffer *wireFormat = ccnxWireFormatMessage_GetWireFormatBuffer(transportMessage_GetDictionary(entry->transport_msg)); + + if (wireFormat) { + session->sample_bytes_recevied += parcBuffer_Remaining(wireFormat); + } + + + /* add +1 so never have 0 RTT */ + fc_rtt = ((int64_t) now - (int64_t) entry->t_first_request) + 1; + if (fc_rtt <= 0) { + if (rtaLogger_IsLoggable(rtaFramework_GetLogger(session->parent_framework), RtaLoggerFacility_Flowcontrol, PARCLogLevel_Error)) { + rtaLogger_Log(rtaFramework_GetLogger(session->parent_framework), RtaLoggerFacility_Flowcontrol, PARCLogLevel_Error, __func__, + "session %p sock %3d : recv segment %" PRIu64 " with negative RTT, t = %" PRIu64 "", + (void *) session, + rtaConnection_GetConnectionId(session->parent_connection), + entry->segnum, + entry->t); + } + + return; + } + + /* record the absolute minimum RTT ever seen */ + if (fc_rtt < session->base_RTT) { + session->base_RTT = fc_rtt; + } + + /* find the minimum RTT for the sample period */ + session->min_RTT = min(session->min_RTT, fc_rtt); + session->cnt_RTT++; + session->sum_RTT += fc_rtt; + + // calculate RTO as per RFC6298 + if (entry->first_request) { + if (session->SRTT == 0) { + // this is the first one, so do 2.2 + session->SRTT = fc_rtt; + session->RTTVAR = fc_rtt >> 1; + session->RTO = session->SRTT + + max(rtaFramework_UsecToTicks(1000000), 4 * session->RTTVAR); + } else { + // RTTVAR <- (1 - beta) * RTTVAR + beta * |SRTT - R'| + // using beta = 1/4, so we want 3/4 * RTTVAR + int64_t abs = ((int64_t) session->SRTT - (int64_t) fc_rtt); + + if (abs < 0) { + abs = -1 * abs; + } + + session->RTTVAR = ((session->RTTVAR >> 1) + (session->RTTVAR >> 2)) + (abs >> 2); + + // SRTT <- (1 - alpha) * SRTT + alpha * R' + // using alpha = 1/8 and (1-alpha) = 1/2 + 1/4 + 1/8 = 7/8 + session->SRTT = (session->SRTT >> 1) + (session->SRTT >> 2) + (session->SRTT >> 3) + (abs >> 3); + + session->RTO = session->SRTT + + max(rtaFramework_UsecToTicks(1000000), 4 * session->RTTVAR); + } + } + + // we received a packet :) yay. + // we get to extend the RTO expiry + session->next_rto = now + session->RTO; +} + +/* + * called inside workq_mutex lock. + * After we deliver each segment, we increment session->starting_segnum. After we deliver the + * the terminal segement of a stream, session->starting_segnum will be 1 past the final block id. + */ +static void +vegasSession_ForwardObjectsInOrder(VegasSession *session) +{ + while (session->window_head != session->window_tail) { + struct fc_window_entry *entry = &session->window[ session->window_head ]; + + // sanity checks + assertTrue(entry->valid, "Window entry %p for window_head index %u", (void *) entry, session->window_head); + assertTrue(entry->segnum == session->starting_segnum, + "Expected seqnum not equal to window entry, expected %" PRIu64 ", got %" PRIu64, + session->starting_segnum, + entry->segnum); + + if (entry->transport_msg != NULL) { + PARCEventQueue *out = rtaComponent_GetOutputQueue(session->parent_connection, FC_VEGAS, RTA_UP); + RtaComponentStats *stats = rtaConnection_GetStats(session->parent_connection, FC_VEGAS); + + if (rtaLogger_IsLoggable(rtaFramework_GetLogger(session->parent_framework), RtaLoggerFacility_Flowcontrol, PARCLogLevel_Debug)) { + rtaLogger_Log(rtaFramework_GetLogger(session->parent_framework), RtaLoggerFacility_Flowcontrol, PARCLogLevel_Debug, __func__, + "session %p fd %d forward segment %" PRIu64 " up stack", + (void *) session, + rtaConnection_GetConnectionId(session->parent_connection), + entry->segnum); + } + + if (rtaComponent_PutMessage(out, entry->transport_msg)) { + // if we successfully put the message up the stack, null + // the entry so the transport message will not be destroyed + // when this window entry is released. + entry->transport_msg = NULL; + rtaComponentStats_Increment(stats, STATS_UPCALL_OUT); + } + + vegasSession_ReleaseWindowEntry(entry); + session->starting_segnum++; + session->window_head = (session->window_head + 1) % FC_MAX_CWND; + } else { + if (rtaLogger_IsLoggable(rtaFramework_GetLogger(session->parent_framework), RtaLoggerFacility_Flowcontrol, PARCLogLevel_Debug)) { + rtaLogger_Log(rtaFramework_GetLogger(session->parent_framework), RtaLoggerFacility_Flowcontrol, PARCLogLevel_Debug, __func__, + "session %p fd %d no message segment %" PRIu64 ", no more in order messages", + rtaConnection_GetConnectionId(session->parent_connection), + entry->segnum); + } + + return; + } + } +} + +static int +fc_ssthresh(VegasSession *session) +{ + return min(session->slow_start_threshold, session->current_cwnd - 1); +} + +/** + * Slow-start increase, double the cwnd + */ +static void +fc_slow_start(VegasSession *session) +{ + session->last_cwnd_adjust = rtaFramework_GetTicks(session->parent_framework); + session->current_cwnd = session->current_cwnd << 1; +} + +static +int +fc_in_cwnd_reduction(VegasSession *session) +{ + return 0; +} + +/* + * Similar to the tcp_current_ssthresh. If cwnd > ssthresh, then + * increase ssthres to 1/2 to cwnd, except if we're in a cwnd reduction + * period. + */ +static inline uint32_t +fc_current_ssthresh(VegasSession *session) +{ + if (fc_in_cwnd_reduction(session)) { + return session->slow_start_threshold; + } else { + return max(session->slow_start_threshold, + ((session->current_cwnd >> 1) + + (session->current_cwnd >> 2))); + } +} + +static void +vegasSession_CongestionAvoidanceDebug(VegasSession *session, ticks now) +{ + if (rtaLogger_IsLoggable(rtaFramework_GetLogger(session->parent_framework), RtaLoggerFacility_Flowcontrol, PARCLogLevel_Debug)) { + ticks diff = 0; + + if (session->min_RTT != INT_MAX) { + diff = session->current_cwnd * (session->min_RTT - session->base_RTT) / session->base_RTT; + } + + rtaLogger_Log(rtaFramework_GetLogger(session->parent_framework), RtaLoggerFacility_Flowcontrol, PARCLogLevel_Debug, __func__, + "session %p do_cong %d currentRTT %5" PRIu64 " cntRTT %3d minRTT %5" PRId64 " baseRTT %5" PRId64 " cwnd %3d next %8" PRIu64 " SRTT %" PRIu64 " RTO %" PRIu64 " oldsegs %" PRIu64 " fast %" PRIu64 " diff %" PRIu64 " allocs %u", + (void *) session, + session->do_fc_this_rtt, + session->current_rtt, + session->cnt_RTT, + session->min_RTT == INT_MAX ? 0 : session->min_RTT, + session->base_RTT == INT_MAX ? 0 : session->base_RTT, + session->current_cwnd, + session->next_rtt_sample, + session->SRTT, + session->RTO, + session->cnt_old_segments, + session->cnt_fast_reexpress, + diff, + parcMemory_Outstanding()); + } +} + +static void +vegasSession_LossBasedAvoidance(VegasSession *session) +{ + session->current_rtt = session->current_rtt * 2; + if (session->current_rtt > 4000) { + session->current_rtt = 4000; + } +} + +/** + * This is the Vegas algorithm + */ +static void +vegasSession_TimeBasedAvoidance(VegasSession *session) +{ + ticks rtt, diff; + uint64_t target_cwnd; + + rtt = session->min_RTT; + + /* + * calculate the target cwnd in segments + */ + target_cwnd = session->current_cwnd * session->base_RTT / rtt; + + diff = session->current_cwnd * (rtt - session->base_RTT) / session->base_RTT; + + if ((diff > _gamma && session->current_cwnd <= session->slow_start_threshold)) { + /* If we're in slow start and going too fast, slow down */ + session->current_cwnd = min(session->current_cwnd, (uint32_t) target_cwnd + 1); + session->slow_start_threshold = fc_ssthresh(session); + session->last_cwnd_adjust = rtaFramework_GetTicks(session->parent_framework); + } else if (session->current_cwnd <= session->slow_start_threshold) { + /* Slow start */ + fc_slow_start(session); + } else { + /* Congestion avoidance. */ + + // if (diff > beta || session->cnt_old_segments ) { + if (diff > beta) { + /* The old window was too fast, so + * we slow down. + */ + + session->current_cwnd--; + session->slow_start_threshold = fc_ssthresh(session); + session->last_cwnd_adjust = rtaFramework_GetTicks(session->parent_framework); + } else if (diff < alpha) { + /* room to grow */ + session->current_cwnd++; + session->last_cwnd_adjust = rtaFramework_GetTicks(session->parent_framework); + } else { + /* middle ground, no changes necessary */ + } + } + + if (session->current_cwnd < 2) { + session->current_cwnd = 2; + } else if (session->current_cwnd > FC_MAX_CWND) { + session->current_cwnd = FC_MAX_CWND; + } + + session->slow_start_threshold = fc_current_ssthresh(session); +} + +static void +vegasSession_CongestionAvoidance(VegasSession *session) +{ + ticks now = rtaFramework_GetTicks(session->parent_framework); + + vegasSession_CongestionAvoidanceDebug(session, now); + + if (session->do_fc_this_rtt) { + if (session->cnt_RTT <= 2) { + vegasSession_LossBasedAvoidance(session); + } else { + vegasSession_TimeBasedAvoidance(session); + } + + session->do_fc_this_rtt = 0; + } else { + session->do_fc_this_rtt = 1; + } + + // Now finish up the statistics and setup for next RTT interval + + session->next_rtt_sample = now + session->current_rtt; + + // low-pass filter the base_RTT from the min_RTT + // base_RTT = 15/16 base_RTT + 1/16 min_RTT = (240 * base_RTT + 16 * min_RTT ) / 256 + + if (!USE_MIN_BASE_RTT && (session->cnt_RTT > 0)) { + session->base_RTT = (240 * session->base_RTT + 16 * session->min_RTT) >> 8; + if (session->base_RTT == 0) { + session->base_RTT = 1; + } + } + + // Smooth the RTT for (3 * current + 1 * minimum) / 4 + + if (session->cnt_RTT > 0) { + session->current_rtt = (12 * session->current_rtt + 4 * session->min_RTT) >> 4; + } + + session->current_rtt = max(session->current_rtt, FC_INIT_RTT_MSEC); + + // reset stats + session->sample_bytes_recevied = 0; + session->min_RTT = INT_MAX; + session->cnt_RTT = 0; + session->cnt_old_segments = 0; + session->cnt_fast_reexpress = 0; + session->sum_RTT = 0; + + vegasSession_CongestionAvoidanceDebug(session, now); +} + +/** + * Slow (course grain) retransmission due to RTO expiry. + * Re-express the first segment of the window. + */ +static +void +vegasSession_SlowReexpress(VegasSession *session) +{ + struct fc_window_entry *entry = &session->window[ session->window_head ]; + + assertTrue(entry->valid, "entry %p segnum %" PRIu64 " invalid state, in window but not valid", + (void *) entry, entry->segnum); + + if (rtaLogger_IsLoggable(rtaFramework_GetLogger(session->parent_framework), RtaLoggerFacility_Flowcontrol, PARCLogLevel_Info)) { + rtaLogger_Log(rtaFramework_GetLogger(session->parent_framework), RtaLoggerFacility_Flowcontrol, PARCLogLevel_Info, __func__, + "Session %p conn %p RTO re-expression for segnum %" PRIu64 "", + (void *) session, (void *) session->parent_connection, entry->segnum); + } + + entry->first_request = false; + vegasSession_ExpressInterestForEntry(session, entry); +} + +/** + * Do fast retransmissions based on SRTT smoothed estimate. + * ack_entry is the entry for a content object we just received. Look earlier segments + * and if they were asked for more than SRTT ago, ask again. + */ +static void +vegasSession_FastReexpress(VegasSession *session, struct fc_window_entry *ack_entry) +{ + ticks now = rtaFramework_GetTicks(session->parent_framework); + int64_t delta; + uint64_t segnum; + uint64_t top_segnum; + + // This method is called after forward_in_order, so it's possible that + // ack_entry is no longer valid, meaning we've moved the window past it. + // In that case, we're done. + if (ack_entry->valid == false) { + return; + } + + // we don't retransmit beyond the current cwnd. ack_entry might be outside + // the cwnd. + + top_segnum = min(ack_entry->segnum, session->starting_segnum + session->current_cwnd); + + for (segnum = session->starting_segnum; segnum < top_segnum; segnum++) { + int index = (session->window_head + (segnum - session->starting_segnum)) % FC_MAX_CWND; + delta = (int64_t) now - ((int64_t) session->window[index].t + (int64_t) session->SRTT); + + // allow up to -1 slack, because the RunAlgorithm adds +1 to fc_rtt. + if (delta >= -1) { + // we have past the SRTT timeout + + // if we last re-transmitted him since the last cwnd adjustment, adjust again + if ((int64_t) session->window[index].t - (int64_t) session->last_cwnd_adjust >= 0) { + vegasSession_ReduceCongestionWindow(session); + } + + if (rtaLogger_IsLoggable(rtaFramework_GetLogger(session->parent_framework), RtaLoggerFacility_Flowcontrol, PARCLogLevel_Info)) { + rtaLogger_Log(rtaFramework_GetLogger(session->parent_framework), RtaLoggerFacility_Flowcontrol, PARCLogLevel_Info, __func__, + "session %p conn %p RTO re-expression for segnum %" PRIu64 "", + (void *) session, (void *) session->parent_connection, session->window[index].segnum); + } + + session->window[index].first_request = false; + session->cnt_fast_reexpress++; + vegasSession_ExpressInterestForEntry(session, &session->window[index]); + } + } +} + +/** + * Generates an Interest message for the window entry. + * + * No side effects, apart from putting on Interest on the down queue. + * If the down direction is blocked, this function will not put an interest in the down queue. It will + * look like a lost interest to the flow controller, which should cause the flow controller to slow down. + * + * @param [<#in out in,out#>] <#name#> <#description#> + * + * @return <#value#> <#explanation#> + * + * Example: + * @code + * <#example#> + * @endcode + */ +static int +vegasSession_ExpressInterestForEntry(VegasSession *session, struct fc_window_entry *entry) +{ + if (!rtaConnection_BlockedDown(session->parent_connection)) { + ticks now = rtaFramework_GetTicks(session->parent_framework); + PARCEventQueue *q_out; + TransportMessage *tm_out; + CCNxName *chunk_name; + + entry->t = now; + + chunk_name = ccnxName_Copy(session->basename); + + CCNxNameSegment *segment = ccnxNameSegmentNumber_Create(CCNxNameLabelType_CHUNK, entry->segnum); + ccnxName_Append(chunk_name, segment); + ccnxNameSegment_Release(&segment); + + assertNotNull(session->interestInterface, "Got a NULL interestInterface. Should not happen."); + + CCNxTlvDictionary *interestDictionary = + session->interestInterface->create(chunk_name, + session->lifetime, + NULL, // ppkid + NULL, // content object hash + CCNxInterestDefault_HopLimit); + + if (session->keyIdRestriction != NULL) { + session->interestInterface->setKeyIdRestriction(interestDictionary, session->keyIdRestriction); + } + + tm_out = transportMessage_CreateFromDictionary(interestDictionary); + transportMessage_SetInfo(tm_out, rtaConnection_Copy(session->parent_connection), rtaConnection_FreeFunc); + + q_out = rtaComponent_GetOutputQueue(session->parent_connection, FC_VEGAS, RTA_DOWN); + + if (rtaLogger_IsLoggable(rtaFramework_GetLogger(session->parent_framework), RtaLoggerFacility_Flowcontrol, PARCLogLevel_Debug)) { + char *string = ccnxName_ToString(chunk_name); + rtaLogger_Log(rtaFramework_GetLogger(session->parent_framework), RtaLoggerFacility_Flowcontrol, PARCLogLevel_Debug, __func__, + "session %p entry %p segname %p segnum %" PRIu64 " %s sent", + (void *) session, + (void *) entry, + (void *) chunk_name, + entry->segnum, + string); + parcMemory_Deallocate((void **) &string); + } + + ccnxTlvDictionary_Release(&interestDictionary); + ccnxName_Release(&chunk_name); + + if (rtaComponent_PutMessage(q_out, tm_out)) { + rtaComponentStats_Increment(rtaConnection_GetStats(session->parent_connection, FC_VEGAS), + STATS_DOWNCALL_OUT); + } + } else { + if (rtaLogger_IsLoggable(rtaFramework_GetLogger(session->parent_framework), RtaLoggerFacility_Flowcontrol, PARCLogLevel_Info)) { + CCNxName *segment_name = ccnxName_Copy(session->basename); + ccnxName_Append(segment_name, ccnxNameSegmentNumber_Create(CCNxNameLabelType_CHUNK, entry->segnum)); + char *string = ccnxName_ToString(segment_name); + rtaLogger_Log(rtaFramework_GetLogger(session->parent_framework), RtaLoggerFacility_Flowcontrol, PARCLogLevel_Info, __func__, + "session %p entry %p segname %p segnum %" PRIu64 " %s SUPPRESSED BLOCKED DOWN QUEUE", + (void *) session, + (void *) entry, + (void *) segment_name, + entry->segnum, + string); + parcMemory_Deallocate((void **) &string); + ccnxName_Release(&segment_name); + } + } + + return 0; +} + +/* + * Express interests out to the max allowed by the cwnd. This function will operate + * even if the down queue is blocked. Those interests will be treated as lost, which will cause + * the flow controller to slow down. + */ +static void +vegasSession_ExpressInterests(VegasSession *session) +{ + ticks now = rtaFramework_GetTicks(session->parent_framework); + + // how many interests are currently outstanding? + int wsize = session->window_tail - session->window_head; + if (wsize < 0) { + wsize += FC_MAX_CWND; + } + + // if we know the FBID, don't ask for anything beyond that + while (wsize < session->current_cwnd && (wsize + session->starting_segnum <= session->final_segnum)) { + // expreess them + struct fc_window_entry *entry = &session->window[session->window_tail]; + + assertFalse(entry->valid, + "Window entry %d marked as valid, but its outside the cwind!", + session->window_tail); + + session->window_tail = (session->window_tail + 1) % FC_MAX_CWND; + + memset(entry, 0, sizeof(struct fc_window_entry)); + + entry->valid = true; + entry->segnum = session->starting_segnum + wsize; + entry->first_request = true; + entry->t_first_request = now; + + if (session->sample_in_progress == 0) { + // make this interest the sample for the RTT + session->sample_in_progress = true; + session->sample_segnum = entry->segnum; + session->sample_start = now; + session->sample_bytes_recevied = 0; + } + + vegasSession_ExpressInterestForEntry(session, entry); + + wsize++; + } +} + +/* + * This is dispatched from the event loop, so its a loosely accurate time + */ +static void +vegasSession_TimerCallback(int fd, PARCEventType what, void *user_data) +{ + VegasSession *session = (VegasSession *) user_data; + int64_t delta; + ticks now; + + assertTrue(what & PARCEventType_Timeout, "%s got unknown signal %d", __func__, what); + + now = rtaFramework_GetTicks(session->parent_framework); + delta = ((int64_t) now - (int64_t) session->next_rtt_sample); + + if (delta >= 0) { + if (rtaLogger_IsLoggable(rtaFramework_GetLogger(session->parent_framework), RtaLoggerFacility_Flowcontrol, PARCLogLevel_Debug)) { + rtaLogger_Log(rtaFramework_GetLogger(session->parent_framework), RtaLoggerFacility_Flowcontrol, PARCLogLevel_Debug, __func__, + "Session %p processing timer, delta %" PRId64, + (void *) session, delta); + } + + // This entry is ready for processing + vegasSession_CongestionAvoidance(session); + + // set the next timer + vegasSession_SetTimer(session, session->current_rtt); + } else { + vegasSession_SetTimer(session, -1 * delta); + } + + // check for retransmission + delta = ((int64_t) now - (int64_t) session->next_rto); + if (delta >= 0) { + // Do this once per RTO + vegasSession_SlowReexpress(session); + + // we're now in a doubling regeme. Reset the + // moving average and double the RTO. + session->SRTT = 0; + session->RTTVAR = 0; + session->RTO = session->RTO * 2; + session->next_rto = now + session->RTO; + } +} + +/** + * precondition: the entry is valid + */ +static void +vegasSession_ReleaseWindowEntry(struct fc_window_entry *entry) +{ + assertTrue(entry->valid, "Called on invalid window entry"); + if (!entry->valid) { + return; + } + + if (entry->transport_msg != NULL) { + transportMessage_Destroy(&entry->transport_msg); + } + entry->valid = false; +} + +static void +vegasSession_SetTimer(VegasSession *session, ticks tick_delay) +{ + struct timeval timeout; + uint64_t usec = rtaFramework_TicksToUsec(tick_delay); + const unsigned usec_per_sec = 1000000; + + timeout.tv_sec = usec / usec_per_sec; + timeout.tv_usec = (int) (usec - timeout.tv_sec * usec_per_sec); + + // this replaces any prior events + parcEventTimer_Start(session->tick_event, &timeout); + + if (rtaLogger_IsLoggable(rtaFramework_GetLogger(session->parent_framework), RtaLoggerFacility_Flowcontrol, PARCLogLevel_Debug)) { + rtaLogger_Log(rtaFramework_GetLogger(session->parent_framework), RtaLoggerFacility_Flowcontrol, PARCLogLevel_Debug, __func__, + "session %p tick_delay %" PRIu64 " timeout %.6f", + (void *) session, + tick_delay, + timeout.tv_sec + 1E-6 * timeout.tv_usec); + } +} + +// ============================================= +// Private API + +/** + * Unsets the final segment number indicating we do not know the value + * + * Sets the final segment number to the maximum possible value, which effectively + * lets us run off to infinity. + * + * @param [in] session An allocated vegas session + * + * Example: + * @code + * <#example#> + * @endcode + */ +static void +_vegasSession_UnsetFinalSegnum(VegasSession *session) +{ + session->final_segnum = ULLONG_MAX; +} + +VegasSession * +vegasSession_Create(VegasConnectionState *fc, RtaConnection *conn, CCNxName *basename, segnum_t begin, + CCNxInterestInterface *interestInterface, uint32_t lifetime, PARCBuffer *keyIdRestriction) +{ + assertNotNull(conn, "Called with null connection"); + assertNotNull(basename, + "conn %p connid %u called with null basename", + (void *) conn, + rtaConnection_GetConnectionId(conn)); + + if (conn == NULL || basename == NULL) { + return NULL; + } + + VegasSession *session = parcMemory_AllocateAndClear(sizeof(VegasSession)); + assertNotNull(session, "parcMemory_AllocateAndClear(%zu) returned NULL", sizeof(VegasSession)); + session->parent_connection = conn; + session->parent_framework = rtaProtocolStack_GetFramework(rtaConnection_GetStack(conn)); + session->interestInterface = interestInterface; + session->lifetime = lifetime; + session->basename = basename; + if (keyIdRestriction != NULL) { + session->keyIdRestriction = parcBuffer_Acquire(keyIdRestriction); + } + session->parent_fc = fc; + + session->tick_event = parcEventTimer_Create(rtaFramework_GetEventScheduler(session->parent_framework), 0, vegasSession_TimerCallback, (void *) session); + + session->starting_segnum = 0; + session->current_cwnd = FC_INIT_CWND; + session->min_RTT = INT_MAX; + session->base_RTT = INT_MAX; + session->do_fc_this_rtt = 0; + session->current_rtt = rtaFramework_UsecToTicks(FC_INIT_RTT_MSEC * 1000); + session->slow_start_threshold = FC_MAX_SSTHRESH; + + session->SRTT = 0; + session->RTTVAR = 0; + session->RTO = rtaFramework_UsecToTicks(FC_INIT_RTO_MSEC * 1000); + session->next_rto = ULLONG_MAX; + session->cnt_old_segments = 0; + session->cnt_fast_reexpress = 0; + + _vegasSession_UnsetFinalSegnum(session); + + if (rtaLogger_IsLoggable(rtaFramework_GetLogger(session->parent_framework), RtaLoggerFacility_Flowcontrol, PARCLogLevel_Notice)) { + rtaLogger_Log(rtaFramework_GetLogger(session->parent_framework), RtaLoggerFacility_Flowcontrol, PARCLogLevel_Notice, __func__, + "session %p initialized connid %u ", + (void *) session, + rtaConnection_GetConnectionId(conn)); + } + return session; +} + +static void +vegasSession_Close(VegasSession *session) +{ + if (rtaLogger_IsLoggable(rtaFramework_GetLogger(session->parent_framework), RtaLoggerFacility_Flowcontrol, PARCLogLevel_Notice)) { + char *p = ccnxName_ToString(session->basename); + rtaLogger_Log(rtaFramework_GetLogger(session->parent_framework), RtaLoggerFacility_Flowcontrol, PARCLogLevel_Notice, __func__, + "session %p close starting segnum %" PRIu64 " final chunk ID %" PRIu64 " for name %s", + (void *) session, session->starting_segnum, session->final_segnum, p); + parcMemory_Deallocate((void **) &p); + } + + ccnxName_Release(&session->basename); + + while (session->window_head != session->window_tail) { + struct fc_window_entry *entry = &session->window[ session->window_head ]; + + // sanity checks + assertTrue(entry->valid, "connid %u session %p entry %d in window but not valid", + rtaConnection_GetConnectionId(session->parent_connection), + (void *) session, + session->window_head); + + if (entry->valid) { + if (rtaLogger_IsLoggable(rtaFramework_GetLogger(session->parent_framework), RtaLoggerFacility_Flowcontrol, PARCLogLevel_Debug)) { + char *p = ccnxName_ToString(session->basename); + rtaLogger_Log(rtaFramework_GetLogger(session->parent_framework), RtaLoggerFacility_Flowcontrol, PARCLogLevel_Debug, __func__, + "session %p releasing window entry %d", (void *) session, session->window_head); + parcMemory_Deallocate((void **) &p); + } + + vegasSession_ReleaseWindowEntry(entry); + } + + session->window_head = (session->window_head + 1) % FC_MAX_CWND; + } +} + +void +vegasSession_Destroy(VegasSession **sessionPtr) +{ + VegasSession *session; + + assertNotNull(sessionPtr, "Called with null double pointer"); + session = *sessionPtr; + + if (session->keyIdRestriction != NULL) { + parcBuffer_Release(&session->keyIdRestriction); + } + + vegasSession_Close(session); + + parcEventTimer_Destroy(&(session->tick_event)); + parcMemory_Deallocate((void **) &session); + sessionPtr = NULL; +} + +int +vegasSession_Start(VegasSession *session) +{ + ticks now = rtaFramework_GetTicks(session->parent_framework); + + // express the initial interests + vegasSession_ExpressInterests(session); + + session->next_rtt_sample = now - 1; + session->next_rto = now + session->RTO; + + // put it on the work queue for procesing + + vegasSession_SetTimer(session, session->current_rtt); + + if (rtaLogger_IsLoggable(rtaFramework_GetLogger(session->parent_framework), RtaLoggerFacility_Flowcontrol, PARCLogLevel_Info)) { + rtaLogger_Log(rtaFramework_GetLogger(session->parent_framework), RtaLoggerFacility_Flowcontrol, PARCLogLevel_Info, __func__, + "Session %p start", (void *) session); + } + + return 0; +} + +int +vegasSession_Pause(VegasSession *session) +{ + trapNotImplemented("vegasSession_Pause"); +} + +int +vegasSession_Resume(VegasSession *session) +{ + trapNotImplemented("vegasSession_Resume"); +} + +int +vegasSession_Seek(VegasSession *session, segnum_t absolutePosition) +{ + trapNotImplemented("vegasSession_See)"); +} + +/** + * Retrieves the final block ID from the content object + * + * Retreives the final block ID from the object, if it exists, and returns it in + * an output parameter. Returns true if found and returned, false otherwise. + * + * @param [in] obj The Content Object to get the FBID form + * @param [out] output Pointer to the seqnum ouptut + * + * @return true If the content object contained a FBID and the output set + * @return false If there is no FBID in the content object + * + * Example: + * @code + * <#example#> + * @endcode + */ +static bool +vegasSession_GetFinalBlockIdFromContentObject(CCNxTlvDictionary *obj, uint64_t *output) +{ + bool result = false; + if (ccnxContentObject_HasFinalChunkNumber(obj)) { + *output = ccnxContentObject_GetFinalChunkNumber(obj); + result = true; + } + return result; +} + +/** + * Sets the final block id in the session based on the signed info + * + * If the final block id exists in the signed info, set the session's FBID. + * + * Rules on FinalChunkNumber: + * + * 1) The “final chunk” of a stream is identified by a content object having a FinalChunkNumber + * set in its metadata that equals the chunk number in its name. + * + * 2) An application may set the FinalChunkNumber early to let a receiver know when the end is coming. These early advisories are not binding. + * + * 3) If the application has ever set the FinalChunkNumber it may not decrease it. If the actual end happens before a previous advisory, + * the application must publish no-payload content objects such that Rule #1 is satisfied + * + * + * @param [in,out] session The Vegas session + * @param [in] obj The signed content object to get the FBID from + * @param [in] nameChunkNumber is the chunk number in the name + * + * Example: + * @code + * <#example#> + * @endcode + */ +static void +vegasSession_SetFinalBlockId(VegasSession *session, CCNxTlvDictionary *contentObjectDictionary, uint64_t nameChunkNumber) +{ + // Get the FinalChunkNumber out of the metadata and update our notion of it + uint64_t finalChunkNumber; + if (vegasSession_GetFinalBlockIdFromContentObject(contentObjectDictionary, &finalChunkNumber)) { + session->final_segnum = finalChunkNumber; + + if (rtaLogger_IsLoggable(rtaFramework_GetLogger(session->parent_framework), RtaLoggerFacility_Flowcontrol, PARCLogLevel_Info)) { + rtaLogger_Log(rtaFramework_GetLogger(session->parent_framework), RtaLoggerFacility_Flowcontrol, PARCLogLevel_Info, __func__, + "Session %p finalChunkNumber %" PRIu64, (void *) session, session->final_segnum); + } + } else { + // There is no final chunk number in the metadata. If the nameChunkNumber == session->final_seqnum, then + // our idea of the final_seqnum is wrong and we should unset it as the producer did not actually close + // the stream when they said they would + + if (session->final_segnum == nameChunkNumber) { + if (rtaLogger_IsLoggable(rtaFramework_GetLogger(session->parent_framework), RtaLoggerFacility_Flowcontrol, PARCLogLevel_Warning)) { + rtaLogger_Log(rtaFramework_GetLogger(session->parent_framework), RtaLoggerFacility_Flowcontrol, PARCLogLevel_Warning, __func__, + "Session %p finalChunkNumber %" PRIu64 " not set in final chunk, resetting", + (void *) session, session->final_segnum); + } + + _vegasSession_UnsetFinalSegnum(session); + } + } +} + +/** + * We received a duplicate segment from before the start of the current congestion window + * + * + * If we receive a segment from before the start of the current congestion window, then it + * must be a duplicate (we don't have skip forward implemented). Reduce the congestion window size. + * We only reduce the window once per RTT interval no matter how many early duplicates we get. + * + * @param [in,out] session The Vegas session to reduce the window of. + * + * Example: + * @code + * <#example#> + * @endcode + */ +static void +vegasSession_ReceivedBeforeWindowStart(VegasSession *session, uint64_t segnum) +{ + // once per cwnd, reduce the window on out-of-order + if (session->cnt_old_segments == 0) { + vegasSession_ReduceCongestionWindow(session); + } + + session->cnt_old_segments++; + + if (rtaLogger_IsLoggable(rtaFramework_GetLogger(session->parent_framework), RtaLoggerFacility_Flowcontrol, PARCLogLevel_Debug)) { + rtaLogger_Log(rtaFramework_GetLogger(session->parent_framework), RtaLoggerFacility_Flowcontrol, PARCLogLevel_Debug, __func__, + "Session %p connid %3u : recv old segment %" PRIu64 ", starting is %" PRIu64 ", cnt %" PRIu64 "", + (void *) session, + rtaConnection_GetConnectionId(session->parent_connection), + segnum, + session->starting_segnum, + session->cnt_old_segments); + } +} + +static void +vegasSession_SendMoreInterests(VegasSession *session, struct fc_window_entry *entry) +{ + // This will check if there's any earlier segments whose + // RTT has expired and will re-ask for them. This is the + // out-of-order fast retransmit. + vegasSession_FastReexpress(session, entry); + + // have we finished? + if (session->starting_segnum < session->final_segnum) { + // express more interests if we have the window for it + vegasSession_ExpressInterests(session); + } else + if (session->starting_segnum > session->final_segnum) { + // if starting_segment > final_segnum it means that we have delivered the last + // segment up the stack. + + if (rtaLogger_IsLoggable(rtaFramework_GetLogger(session->parent_framework), RtaLoggerFacility_Flowcontrol, PARCLogLevel_Info)) { + rtaLogger_Log(rtaFramework_GetLogger(session->parent_framework), RtaLoggerFacility_Flowcontrol, PARCLogLevel_Info, __func__, + "Session %p connid %u starting_segnum %" PRIu64 ", final_segnum %" PRIu64 ", FINAL SEGMENT DELIVERED, CLOSING", + (void *) session, + rtaConnection_GetConnectionId(session->parent_connection), + session->starting_segnum, + session->final_segnum); + } + + parcEventTimer_Stop(session->tick_event); + vegas_EndSession(session->parent_fc, session); + } + // else session->starting_segnum == session->final_segnum, we're not done yet. +} + +static CCNxName * +vegasSession_GetNameFromTransportMessage(TransportMessage *tm) +{ + CCNxName *name = NULL; + CCNxTlvDictionary *dictionary = transportMessage_GetDictionary(tm); + switch (ccnxTlvDictionary_GetSchemaVersion(dictionary)) { + case CCNxTlvDictionary_SchemaVersion_V1: + name = ccnxTlvDictionary_GetName(dictionary, CCNxCodecSchemaV1TlvDictionary_MessageFastArray_NAME); + break; + + default: + break; + } + return name; +} + + + +int +vegasSession_ReceiveContentObject(VegasSession *session, TransportMessage *tm) +{ + assertTrue(transportMessage_IsContentObject(tm), + "Transport message is not a content object"); + + if (rtaLogger_IsLoggable(rtaFramework_GetLogger(session->parent_framework), RtaLoggerFacility_Flowcontrol, PARCLogLevel_Debug)) { + CCNxName *name = vegasSession_GetNameFromTransportMessage(tm); + char *nameString = NULL; + if (name) { + nameString = ccnxName_ToString(name); + } + rtaLogger_Log(rtaFramework_GetLogger(session->parent_framework), RtaLoggerFacility_Flowcontrol, PARCLogLevel_Debug, __func__, + "Session %p connid %3u receive tm %p: %s", + (void *) session, + rtaConnection_GetConnectionId(session->parent_connection), + (void *) tm, + nameString); + if (nameString) { + parcMemory_Deallocate((void **) &nameString); + } + } + + CCNxTlvDictionary *contentObjectDictionary = transportMessage_GetDictionary(tm); + + // get segment number + uint64_t segnum; + int res = vegasSession_GetSegnumFromObject(contentObjectDictionary, &segnum); + if (res != 0) { + if (rtaLogger_IsLoggable(rtaFramework_GetLogger(session->parent_framework), RtaLoggerFacility_Flowcontrol, PARCLogLevel_Warning)) { + CCNxName *name = vegasSession_GetNameFromTransportMessage(tm); + char *nameString = NULL; + if (name) { + nameString = ccnxName_ToString(name); + } + rtaLogger_Log(rtaFramework_GetLogger(session->parent_framework), RtaLoggerFacility_Flowcontrol, PARCLogLevel_Warning, __func__, + "Session %p connid %3u receive tm %p has no segment number: %s", + (void *) session, + rtaConnection_GetConnectionId(session->parent_connection), + (void *) tm, + nameString); + if (nameString) { + parcMemory_Deallocate((void **) &nameString); + } + } + + // couldn't figure it out + transportMessage_Destroy(&tm); + return -1; + } + + // drop out of order + if (segnum < session->starting_segnum) { + vegasSession_ReceivedBeforeWindowStart(session, segnum); + + if (rtaLogger_IsLoggable(rtaFramework_GetLogger(session->parent_framework), RtaLoggerFacility_Flowcontrol, PARCLogLevel_Debug)) { + rtaLogger_Log(rtaFramework_GetLogger(session->parent_framework), RtaLoggerFacility_Flowcontrol, PARCLogLevel_Debug, __func__, + "Session %p connid %3u : tm %p received segnum %" PRIu64 " before current head %" PRIu64 "", + (void *) session, + __func__, + rtaConnection_GetConnectionId(session->parent_connection), + (void *) tm, + segnum, + session->starting_segnum); + } + + transportMessage_Destroy(&tm); + return -1; + } + + // Update our idea of the final chunk number. This must be done + // before running the algorithm because session->final_segnum is used + // to decide if we're done. + vegasSession_SetFinalBlockId(session, contentObjectDictionary, segnum); + + + // now run the algorithm on the received object + + struct fc_window_entry *entry = vegasSession_GetWindowEntry(session, tm, segnum); + + if (rtaLogger_IsLoggable(rtaFramework_GetLogger(session->parent_framework), RtaLoggerFacility_Flowcontrol, PARCLogLevel_Debug)) { + CCNxName *name = vegasSession_GetNameFromTransportMessage(tm); + char *nameString = NULL; + if (name) { + nameString = ccnxName_ToString(name); + } + rtaLogger_Log(rtaFramework_GetLogger(session->parent_framework), RtaLoggerFacility_Flowcontrol, PARCLogLevel_Debug, __func__, + "Session %p connid %3u receive tm %p segment %" PRIu64 " receive: %s", + (void *) session, + rtaConnection_GetConnectionId(session->parent_connection), + (void *) tm, + segnum, + nameString); + if (nameString) { + parcMemory_Deallocate((void **) &nameString); + } + } + + vegasSession_RunAlgorithmOnReceive(session, entry); + + // forward in-order objects to the user fc + if (!rtaConnection_BlockedUp(session->parent_connection)) { + vegasSession_ForwardObjectsInOrder(session); + } + + vegasSession_SendMoreInterests(session, entry); + + return 0; +} + +unsigned +vegasSession_GetConnectionId(VegasSession *session) +{ + assertNotNull(session, "Parameter session must be non-null"); + return rtaConnection_GetConnectionId(session->parent_connection); +} + +void +vegasSession_StateChanged(VegasSession *session) +{ + if (rtaConnection_BlockedUp(session->parent_connection)) { + // if we're blocked in the up direction, don't do anything. We make this + // check every time we're about ti send stuff up the stack in vegasSession_ReceiveContentObject(). + } else { + // unblocked, forward packets + vegasSession_ForwardObjectsInOrder(session); + } + + if (rtaConnection_BlockedDown(session->parent_connection)) { + // stop generating interests + } else { + // restart interests + } +} |