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support partial rateless decode with re-NACK + enhance mock

pull/102/head
Joseph Calderon 2026-07-12 20:19:34 -07:00
parent c7d943aea8
commit 2d653628ce
6 changed files with 348 additions and 94 deletions
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233
examples/normRatelessTest.cpp
View File

@ -1,40 +1,128 @@
#include <normApi.h>
#include <normEncoder.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <time.h>
#include <sys/select.h>
#include <sys/time.h>
class MockRatelessEncoder : public NormEncoder {
// FEC ID for the (partially-specified) rateless code family.
static const UINT8 RATELESS_FEC_ID = 131;
// Deterministic permutation of [0, n) shared by encoder and decoder.
// The seed depends only on "n", so both sides produce the identical ordering.
static void BuildRatelessPermutation(unsigned int* perm, unsigned int n)
{
for (unsigned int i = 0; i < n; i++) perm[i] = i;
unsigned int state = 0x9e3779b9u ^ n;
for (unsigned int i = n; i > 1; i--)
{
state = state * 1103515245u + 12345u;
unsigned int j = (state >> 8) % i;
unsigned int t = perm[i - 1]; perm[i - 1] = perm[j]; perm[j] = t;
}
}
class MockRatelessEncoder : public NormEncoder
{
public:
virtual bool Init(unsigned int numData, unsigned int numParity, UINT16 vectorSize) {
MockRatelessEncoder() : ndata(0), vec_size(0), perm(NULL) {}
virtual ~MockRatelessEncoder() { Destroy(); }
virtual bool Init(unsigned int numData, unsigned int /*numParity*/, UINT16 vectorSize)
{
Destroy();
ndata = numData;
vec_size = vectorSize;
return true;
perm = new unsigned int[ndata ? ndata : 1];
return (NULL != perm);
}
virtual void Destroy() {}
virtual void Encode(unsigned int segmentId, const char* dataVector, char** parityVectorList) {}
virtual void Destroy() { delete[] perm; perm = NULL; }
// Block-oriented encode is unused by this rateless surrogate; repair
// symbols are synthesized on demand in EncodeParity() below.
virtual void Encode(unsigned int, const char*, char**) {}
// Generate the "parityId"-th repair symbol as a copy of a source symbol
// selected by the shared permutation.
virtual void EncodeParity(unsigned int parityId, const char** sourceVectorList,
unsigned int numData, char* parityVector)
{
if (0 == numData) return;
BuildRatelessPermutation(perm, numData);
unsigned int k = perm[parityId % numData];
if ((k < numData) && (NULL != sourceVectorList[k]))
memcpy(parityVector, sourceVectorList[k], vec_size);
}
virtual bool IsRateless() const { return true; }
private:
unsigned int ndata;
UINT16 vec_size;
unsigned int* perm; // scratch buffer sized to the block size
};
class MockRatelessDecoder : public NormDecoder {
class MockRatelessDecoder : public NormDecoder
{
public:
virtual bool Init(unsigned int numData, unsigned int numParity, UINT16 vectorSize) {
MockRatelessDecoder() : ndata(0), nparity(0), vec_size(0), perm(NULL) {}
virtual ~MockRatelessDecoder() { Destroy(); }
virtual bool Init(unsigned int numData, unsigned int numParity, UINT16 vectorSize)
{
Destroy();
ndata = numData;
nparity = numParity;
vec_size = vectorSize;
return true;
perm = new unsigned int[ndata ? ndata : 1];
return (NULL != perm);
}
virtual void Destroy() {}
virtual int Decode(char** vectorList, unsigned int numData, unsigned int erasureCount, unsigned int* erasureLocs) {
return erasureCount;
virtual void Destroy() { delete[] perm; perm = NULL; }
// Fill erased source symbols using received repair symbols. Returns the
// number of source erasures that could NOT be recovered (0 == success),
// which NORM uses to decide whether to NACK for more repair symbols.
virtual int Decode(char** vectorList, unsigned int numData,
unsigned int erasureCount, unsigned int* erasureLocs)
{
unsigned int total = numData + nparity;
bool* erased = new bool[total];
for (unsigned int i = 0; i < total; i++) erased[i] = false;
for (unsigned int i = 0; i < erasureCount; i++)
if (erasureLocs[i] < total) erased[erasureLocs[i]] = true;
unsigned int sourceErasures = 0;
for (unsigned int i = 0; i < numData; i++)
if (erased[i]) sourceErasures++;
BuildRatelessPermutation(perm, numData);
unsigned int recovered = 0;
for (unsigned int p = 0; (p < nparity) && (recovered < sourceErasures); p++)
{
unsigned int pos = numData + p;
if (erased[pos] || (NULL == vectorList[pos])) continue; // repair symbol not received
unsigned int k = perm[p % numData]; // source symbol this repair carries
if ((k < numData) && erased[k] && (NULL != vectorList[k]))
{
memcpy(vectorList[k], vectorList[pos], vec_size);
erased[k] = false;
recovered++;
}
}
unsigned int stillMissing = sourceErasures - recovered;
delete[] erased;
return (int)stillMissing;
}
private:
unsigned int ndata;
unsigned int nparity;
UINT16 vec_size;
unsigned int* perm;
};
extern "C" {
@ -42,47 +130,126 @@ extern "C" {
NormDecoder* CreateMockDecoder() { return new MockRatelessDecoder(); }
}
int main(int argc, char* argv[]) {
int main(int /*argc*/, char* /*argv*/[])
{
NormInstanceHandle instance = NormCreateInstance();
if (!instance) return -1;
if (NORM_INSTANCE_INVALID == instance) return -1;
NormSessionHandle session = NormCreateSession(instance, "127.0.0.1", 6003, 1);
if (getenv("NORM_DEBUG") != NULL) NormSetDebugLevel((unsigned int)atoi(getenv("NORM_DEBUG")));
srand((unsigned int)time(NULL));
// Register Rateless Coder (FEC ID 131)
if (!NormRegisterFecCoder(session, 131, CreateMockEncoder, CreateMockDecoder, true)) {
fprintf(stderr, "Failed to register custom FEC codec.\n");
// Use two sessions with DISTINCT node ids on the same multicast group so the
// receiver treats the sender as a genuine remote peer. (A single session
// acting as both sender and receiver would hear its own NACKs and suppress
// subsequent ones, stalling multi-round rateless repair.)
const char* groupAddr = "224.1.2.3";
const UINT16 groupPort = 6003;
NormSessionHandle txSession = NormCreateSession(instance, groupAddr, groupPort, 1);
NormSessionHandle rxSession = NormCreateSession(instance, groupAddr, groupPort, 2);
if ((NORM_SESSION_INVALID == txSession) || (NORM_SESSION_INVALID == rxSession)) return -1;
// Register the mock rateless codec on both the sender and receiver sessions.
if (!NormRegisterFecCoder(txSession, RATELESS_FEC_ID, CreateMockEncoder, CreateMockDecoder, true) ||
!NormRegisterFecCoder(rxSession, RATELESS_FEC_ID, CreateMockEncoder, CreateMockDecoder, true))
{
fprintf(stderr, "normRatelessTest error: failed to register rateless FEC codec\n");
return -1;
}
NormSetRxPortReuse(session, true);
NormSetMulticastLoopback(session, true);
NormSetRxPortReuse(txSession, true);
NormSetRxPortReuse(rxSession, true);
NormSetMulticastLoopback(txSession, true); // let our data reach the rx session on this host
NormSetMulticastLoopback(rxSession, true); // let our NACKs reach the tx session on this host
NormSetTxRate(txSession, 10.0e+06); // 10 Mbps for a quick loopback run
// Start Sender using FEC 131
if (!NormStartSender(session, 1, 1024*1024, 1024, 64, 0, 131)) {
fprintf(stderr, "Failed to start sender.\n");
// Induce loss on the receiver so it must repair via rateless parity.
double lossPct = (getenv("NORM_RX_LOSS") != NULL) ? atof(getenv("NORM_RX_LOSS")) : 10.0;
NormSetRxLoss(rxSession, lossPct);
if (!NormStartReceiver(rxSession, 1024 * 1024))
{
fprintf(stderr, "normRatelessTest error: NormStartReceiver() failed\n");
return -1;
}
printf("Sender started with mock rateless codec. Transmitting...\n");
// 16 source symbols/block, up to 64 repair symbols/block, 512-byte segments.
if (!NormStartSender(txSession, 1, 1024 * 1024, 512, 16, 64, RATELESS_FEC_ID))
{
fprintf(stderr, "normRatelessTest error: NormStartSender() failed\n");
return -1;
}
NormObjectHandle obj = NormDataEnqueue(session, "testdata", 8);
// Build a known payload spanning several blocks (incl. a short final block).
const UINT32 dataLen = 20000;
char* txData = new char[dataLen];
for (UINT32 i = 0; i < dataLen; i++)
txData[i] = (char)((i * 31 + 7) & 0xff);
if (obj) {
NormObjectHandle txObj = NormDataEnqueue(txSession, txData, dataLen);
if (NORM_OBJECT_INVALID == txObj)
{
fprintf(stderr, "normRatelessTest error: NormDataEnqueue() failed\n");
return -1;
}
printf("normRatelessTest: sending %u bytes via mock rateless codec (10%% loss)...\n", dataLen);
int result = -1;
// NormGetNextEvent() blocks, so drive it via select() on the NORM descriptor
// to enforce a wall-clock watchdog (the demo must never hang).
NormDescriptor normFd = NormGetDescriptor(instance);
time_t deadline = time(NULL) + 30;
bool running = true;
while (running) {
while (running && (time(NULL) <= deadline))
{
fd_set fdSet;
FD_ZERO(&fdSet);
FD_SET(normFd, &fdSet);
struct timeval timeout;
timeout.tv_sec = 1;
timeout.tv_usec = 0;
int n = select((int)normFd + 1, &fdSet, NULL, NULL, &timeout);
if (n <= 0) continue; // timeout tick (re-check deadline) or interrupted
NormEvent event;
if (NormGetNextEvent(instance, &event)) {
if (event.type == NORM_TX_FLUSH_COMPLETED) {
printf("Transmission flushed completely.\n");
while (running && NormGetNextEvent(instance, &event, false))
{
switch (event.type)
{
case NORM_RX_OBJECT_COMPLETED:
{
unsigned int rxLen = (unsigned int)NormObjectGetSize(event.object);
const char* rxData = NormDataAccessData(event.object);
if ((rxLen == dataLen) && (NULL != rxData) && (0 == memcmp(rxData, txData, dataLen)))
{
printf("normRatelessTest: received %u bytes, contents verified. PASS\n", rxLen);
result = 0;
}
else
{
fprintf(stderr, "normRatelessTest: received object mismatch (len %u vs %u). FAIL\n",
rxLen, dataLen);
}
running = false;
break;
}
case NORM_RX_OBJECT_ABORTED:
fprintf(stderr, "normRatelessTest error: NORM_RX_OBJECT_ABORTED\n");
running = false;
break;
default:
break;
}
}
}
}
if (running)
fprintf(stderr, "normRatelessTest error: timed out waiting for object reception\n");
NormStopSender(session);
NormStopSender(txSession);
NormStopReceiver(rxSession);
NormDestroyInstance(instance);
delete[] txData;
printf("Success.\n");
return 0;
printf("normRatelessTest: %s\n", (0 == result) ? "SUCCESS" : "FAILURE");
return result;
}

13
include/normEncoder.h
View File

@ -53,7 +53,12 @@ class NormEncoder
virtual bool Init(unsigned int numData, unsigned int numParity, UINT16 vectorSize) = 0;
virtual void Destroy() = 0;
virtual void Encode(unsigned int segmentId, const char *dataVector, char **parityVectorList) = 0;
virtual void EncodeParity(unsigned int parityId, char* parityVector) { (void)parityId; (void)parityVector; }
// Rateless codes generate parity symbols on demand. Unlike the block-oriented
// Encode() above, EncodeParity() is handed the block's source symbol vectors so a
// fountain/rateless encoder can synthesize the "parityId"-th (innovative) repair
// symbol without having to cache source state across calls.
virtual void EncodeParity(unsigned int parityId, const char** sourceVectorList, unsigned int numData, char* parityVector)
{ (void)parityId; (void)sourceVectorList; (void)numData; (void)parityVector; }
virtual bool IsRateless() const { return false; }
virtual UINT16 CalculateProactiveParity(unsigned int blockId, UINT16 numData, const NormTelemetryContext& context) { return 0; }
virtual UINT16 CalculateReactiveParity(unsigned int blockId, UINT16 requestedErasures, const NormTelemetryContext& context) { return requestedErasures; }
@ -65,6 +70,12 @@ class NormDecoder
virtual ~NormDecoder();
virtual bool Init(unsigned int numData, unsigned int numParity, UINT16 vectorSize) = 0;
virtual void Destroy() = 0;
// Decode in place, filling any erased source symbol vectors in "vectorList".
// For ideal (MDS) codes (e.g. Reed-Solomon) the return value is unused by the
// receiver, which assumes success whenever it holds >= erasureCount repair symbols.
// For rateless/non-ideal codes the return value MUST be the number of source
// symbol erasures that could NOT be recovered (0 == fully decoded); the receiver
// uses this to keep the block pending and NACK for additional repair symbols.
virtual int Decode(char** vectorList, unsigned int numData, unsigned int erasureCount, unsigned int* erasureLocs) = 0;
}; // end class NormDecoder

6
include/normSegment.h
View File

@ -163,6 +163,7 @@ class NormBlock
erasure_count = ndata;
parity_count = 0;
parity_offset = 0;
decode_overhead = 0;
flags = 0;
}
// Note: This invalidates the repair_mask state.
@ -172,6 +173,10 @@ class NormBlock
UINT16 ErasureCount() const {return erasure_count;}
void IncrementParityCount() {parity_count++;}
UINT16 ParityCount() const {return parity_count;}
// Extra repair symbols a (rateless) receiver needs beyond ErasureCount() because
// prior decode attempts were short of innovative symbols (0 for ideal MDS codes).
void IncrementDecodeOverhead() {decode_overhead++;}
UINT16 DecodeOverhead() const {return decode_overhead;}
bool GetFirstPending(NormSymbolId& symbolId) const
{
@ -279,6 +284,7 @@ class NormBlock
int flags;
UINT16 erasure_count;
UINT16 parity_count; // how many fresh parity we are currently planning to send
UINT16 decode_overhead; // extra repair symbols a rateless rcvr needs after a short decode
UINT16 parity_offset; // offset from where our fresh parity will be sent
UINT16 seg_size_max;

4
include/normSession.h
View File

@ -560,8 +560,8 @@ class NormSession : public NormTelemetryContext
void SenderEncode(unsigned int segmentId, const char* segment, char** parityVectorList)
{encoder->Encode(segmentId, segment, parityVectorList);}
void SenderEncodeParity(unsigned int parityId, char* parityVector)
{encoder->EncodeParity(parityId, parityVector);}
void SenderEncodeParity(unsigned int parityId, const char** sourceVectorList, unsigned int numData, char* parityVector)
{encoder->EncodeParity(parityId, sourceVectorList, numData, parityVector);}
NormBlock* SenderGetFreeBlock(NormObjectId objectId, NormBlockId blockId);

66
src/common/normObject.cpp
View File

@ -1609,9 +1609,18 @@ void NormObject::HandleObjectMessage(const NormObjectMsg& msg,
} // end if (nextErasure < numData)
} // end if (block->GetFirstPending(nextErasure))
bool ratelessDecodeIncomplete = false;
if (erasureCount)
{
sender->Decode(block->SegmentList(), numData, erasureCount);
// The decoder returns the number of source erasures it could NOT
// recover. Ideal (MDS) codes always fully decode here, so their
// return is effectively ignored; rateless/non-ideal codes may need
// more repair symbols than the "ParityCount >= ErasureCount" guard
// above assumes, so we must honor a partial-decode result.
UINT16 unrecovered = sender->Decode(block->SegmentList(), numData, erasureCount);
ratelessDecodeIncomplete = session.IsRatelessFec(fec_id) && (0 != unrecovered);
if (!ratelessDecodeIncomplete)
{
for (UINT16 i = 0; i < erasureCount; i++)
{
NormSegmentId sid = sender->GetErasureLoc(i);
@ -1638,13 +1647,28 @@ void NormObject::HandleObjectMessage(const NormObjectMsg& msg,
}
}
}
else
{
// Not enough innovative repair symbols yet. Note the shortfall so
// the receiver's next NACK requests additional parity, and leave the
// block pending (its missing source symbols are still marked pending).
block->IncrementDecodeOverhead();
PLOG(PL_DEBUG, "NormObject::HandleObjectMessage() node>%lu sender>%lu obj>%hu blk>%lu "
"rateless decode incomplete (%hu source symbol(s) short); awaiting more parity\n",
(unsigned long)LocalNodeId(), (unsigned long)sender->GetId(),
(UINT16)transport_id, (unsigned long)blockId.GetValue(), unrecovered);
}
}
// Clear any temporarily retrieved segments for the block
for (UINT16 i = 0; i < retrievalCount; i++)
block->DetachSegment(sender->GetRetrievalLoc(i));
if (!ratelessDecodeIncomplete)
{
// OK, we're done with this block
pending_mask.Unset(blockId.GetValue());
block_buffer.Remove(block);
sender->PutFreeBlock(block);
}
} // if erasureCount <= parityCount (i.e., block complete)
// Notify application of new data available
// (TBD) this could be improved for stream objects
@ -2070,6 +2094,25 @@ bool NormObject::NextSenderMsg(NormObjectMsg* msg)
block->UpdateSegSizeMax(payloadLength);
session.SenderEncode(segmentId, data->AccessPayload(), block->SegmentList(numData));
block->IncreaseParityReadiness();
// Rateless codecs synthesize repair symbols on demand from the block's
// source symbols, so retain each source vector in the block as it is sent.
// (This incremental path drives ParityReadiness to completion, after which
// CalculateBlockParity() is skipped, so caching must happen here too.)
if (session.GetEncoder() && session.GetEncoder()->IsRateless() &&
(NULL == block->GetSegment(segmentId)))
{
char* srcSeg = session.SenderGetFreeSegment(transport_id, block->GetId());
if (NULL != srcSeg)
{
memcpy(srcSeg, buffer, payloadMax);
block->AttachSegment(segmentId, srcSeg);
}
else
{
PLOG(PL_INFO, "NormObject::NextSenderMsg() node>%lu warning: no free segment to cache "
"rateless source symbol.\n", (unsigned long)LocalNodeId());
}
}
}
}
else
@ -2092,7 +2135,7 @@ bool NormObject::NextSenderMsg(NormObjectMsg* msg)
payloadMax = MIN(payloadMax, SIM_PAYLOAD_MAX);
#endif // SIMULATE
memset(segment, 0, payloadMax);
session.SenderEncodeParity(segmentId - numData, segment);
session.SenderEncodeParity(segmentId - numData, (const char**)block->SegmentList(), numData, segment);
block->AttachSegment(segmentId, segment);
}
else
@ -2260,6 +2303,25 @@ bool NormObject::CalculateBlockParity(NormBlock* block)
memset(buffer+payloadLength, 0, payloadMax-payloadLength+1);
block->UpdateSegSizeMax(payloadLength);
session.SenderEncode(i, buffer, block->SegmentList(numData));
// Rateless codecs synthesize repair symbols on demand (EncodeParity) from
// the block's source symbols, so cache the source vectors in the block.
// (Block codes like Reed-Solomon accumulate parity above and don't need this.)
if (session.GetEncoder() && session.GetEncoder()->IsRateless() &&
(NULL == block->GetSegment(i)))
{
char* srcSeg = session.SenderGetFreeSegment(transport_id, block->GetId());
if (NULL != srcSeg)
{
memcpy(srcSeg, buffer, payloadMax);
block->AttachSegment(i, srcSeg);
}
else
{
PLOG(PL_INFO, "NormObject::CalculateBlockParity() node>%lu warning: no free segment to cache "
"rateless source symbol.\n", (unsigned long)LocalNodeId());
return false;
}
}
}
else
{

12
src/common/normSegment.cpp
View File

@ -208,8 +208,14 @@ bool NormBlock::IsRepairPending(UINT16 numData, UINT16 numParity)
}
else
{
// We need "erasure_count" repair symbols, plus "decode_overhead" more for
// rateless codes whose earlier repair symbols weren't innovative enough to
// decode (decode_overhead is always 0 for ideal MDS codes, preserving the
// original behavior).
UINT16 parityNeed = erasure_count + decode_overhead;
if (parityNeed > numParity) parityNeed = numParity;
repair_mask.SetBits(0, numData);
repair_mask.SetBits(numData+erasure_count, numParity-erasure_count);
repair_mask.SetBits(numData+parityNeed, numParity-parityNeed);
}
// Calculate repair_mask = pending_mask - repair_mask
repair_mask.XCopy(pending_mask);
@ -535,7 +541,9 @@ bool NormBlock::AppendRepairRequest(NormNackMsg& nack,
{
if (isRateless)
{
int needed = (int)erasure_count - (int)parity_count + (int)fecOverhead;
// "decode_overhead" grows when a prior decode attempt fell short of innovative
// symbols, so the receiver keeps asking for more parity until the block decodes.
int needed = (int)erasure_count - (int)parity_count + (int)fecOverhead + (int)decode_overhead;
if (needed <= 0) return false;
UINT16 needed_clamped = (needed > 65535) ? 65535 : (UINT16)needed;