// The algorithm is as follows. We create M BWTs for subsets of
// the input reads. These are created independently and written
// to disk. They are then merged either sequentially or pairwise
// to create the final BWT
void buildBWTDisk(const BWTDiskParameters& parameters)
{
// Build the initial bwts for subsets of the data
MergeVector mergeVector;
if(parameters.bUseBCR)
mergeVector = computeInitialBCR(parameters);
else
mergeVector = computeInitialSAIS(parameters);
// Phase 2: Pairwise merge the BWTs
int groupID = mergeVector.size(); // Initial the name of the next intermediate bwt
int round = 1;
MergeVector nextMergeRound;
while(mergeVector.size() > 1)
{
std::cout << "Starting round " << round << "\n";
SeqReader* pReader = new SeqReader(parameters.inFile);
SeqRecord record;
for(size_t i = 0; i < mergeVector.size(); i+=2)
{
if(i + 1 != mergeVector.size())
{
std::string bwt_merged_name = makeTempName(parameters.outPrefix, groupID, parameters.bwtExtension);
std::string sai_merged_name = makeTempName(parameters.outPrefix, groupID, parameters.saiExtension);
MergeItem item1 = mergeVector[i];
MergeItem item2 = mergeVector[i+1];
// Perform the actual merge
int64_t curr_idx = merge(pReader, item1, item2,
bwt_merged_name, sai_merged_name,
parameters.bBuildReverse, parameters.numThreads, parameters.storageLevel);
// pReader now points to the end of item1's block of
// reads. Skip item2's reads
assert(curr_idx == item2.start_index);
while(curr_idx <= item2.end_index)
{
bool eof = !pReader->get(record);
assert(!eof);
(void)eof;
++curr_idx;
}
// Create the merged mergeItem to use in the next round
MergeItem merged;
merged.start_index = item1.start_index;
merged.end_index = item2.end_index;
merged.bwt_filename = bwt_merged_name;
merged.sai_filename = sai_merged_name;
nextMergeRound.push_back(merged);
// Done with the temp files, remove them
unlink(item1.bwt_filename.c_str());
unlink(item2.bwt_filename.c_str());
unlink(item1.sai_filename.c_str());
unlink(item2.sai_filename.c_str());
++groupID;
}
else
{
// Singleton, pass through to the next round
nextMergeRound.push_back(mergeVector[i]);
}
}
delete pReader;
mergeVector.clear();
mergeVector.swap(nextMergeRound);
++round;
}
assert(mergeVector.size() == 1);
// Done, rename the files to their final name
std::stringstream bwt_ss;
bwt_ss << parameters.outPrefix << parameters.bwtExtension << (USE_GZ ? ".gz" : "");
std::string bwt_final_filename = bwt_ss.str();
rename(mergeVector.front().bwt_filename.c_str(), bwt_final_filename.c_str());
std::stringstream sai_ss;
sai_ss << parameters.outPrefix << parameters.saiExtension << (USE_GZ ? ".gz" : "");
std::string sai_final_filename = sai_ss.str();
rename(mergeVector.front().sai_filename.c_str(), sai_final_filename.c_str());
}
// The algorithm is as follows. We create M BWTs for subsets of
// the input reads. These are created independently and written
// to disk. They are then merged either sequentially or pairwise
// to create the final BWT
void buildBWTDisk(const std::string& in_filename, const std::string& out_prefix,
const std::string& bwt_extension, const std::string& sai_extension,
bool doReverse, int numThreads, int numReadsPerBatch, int storageLevel)
{
size_t MAX_READS_PER_GROUP = numReadsPerBatch;
SeqReader* pReader = new SeqReader(in_filename);
SeqRecord record;
int groupID = 0;
size_t numReadTotal = 0;
MergeVector mergeVector;
MergeItem mergeItem;
mergeItem.start_index = 0;
// Phase 1: Compute the initial BWTs
ReadTable* pCurrRT = new ReadTable;
bool done = false;
while(!done)
{
done = !pReader->get(record);
if(!done)
{
// the read is valid
SeqItem item = record.toSeqItem();
if(doReverse)
item.seq.reverse();
pCurrRT->addRead(item);
++numReadTotal;
}
if(pCurrRT->getCount() >= MAX_READS_PER_GROUP || (done && pCurrRT->getCount() > 0))
{
// Compute the SA and BWT for this group
SuffixArray* pSA = new SuffixArray(pCurrRT, numThreads);
// Write the BWT to disk
std::string bwt_temp_filename = makeTempName(out_prefix, groupID, bwt_extension);
pSA->writeBWT(bwt_temp_filename, pCurrRT);
std::string sai_temp_filename = makeTempName(out_prefix, groupID, sai_extension);
pSA->writeIndex(sai_temp_filename);
// Push the merge info
mergeItem.end_index = numReadTotal - 1; // inclusive
mergeItem.reads_filename = in_filename;
mergeItem.bwt_filename = bwt_temp_filename;
mergeItem.sai_filename = sai_temp_filename;
mergeVector.push_back(mergeItem);
// Cleanup
delete pSA;
// Start the new group
mergeItem.start_index = numReadTotal;
++groupID;
pCurrRT->clear();
}
}
delete pCurrRT;
delete pReader;
// Phase 2: Pairwise merge the BWTs
int round = 1;
MergeVector nextMergeRound;
while(mergeVector.size() > 1)
{
std::cout << "Starting round " << round << "\n";
pReader = new SeqReader(in_filename);
for(size_t i = 0; i < mergeVector.size(); i+=2)
{
if(i + 1 != mergeVector.size())
{
std::string bwt_merged_name = makeTempName(out_prefix, groupID, bwt_extension);
std::string sai_merged_name = makeTempName(out_prefix, groupID, sai_extension);
MergeItem item1 = mergeVector[i];
MergeItem item2 = mergeVector[i+1];
// Perform the actual merge
int64_t curr_idx = merge(pReader, item1, item2,
bwt_merged_name, sai_merged_name,
doReverse, numThreads, storageLevel);
// pReader now points to the end of item1's block of
// reads. Skip item2's reads
assert(curr_idx == item2.start_index);
while(curr_idx <= item2.end_index)
{
bool eof = !pReader->get(record);
assert(!eof);
(void)eof;
++curr_idx;
}
// Create the merged mergeItem to use in the next round
MergeItem merged;
merged.start_index = item1.start_index;
merged.end_index = item2.end_index;
merged.bwt_filename = bwt_merged_name;
merged.sai_filename = sai_merged_name;
nextMergeRound.push_back(merged);
// Done with the temp files, remove them
unlink(item1.bwt_filename.c_str());
unlink(item2.bwt_filename.c_str());
unlink(item1.sai_filename.c_str());
unlink(item2.sai_filename.c_str());
++groupID;
}
else
{
// Singleton, pass through to the next round
nextMergeRound.push_back(mergeVector[i]);
}
}
delete pReader;
mergeVector.clear();
mergeVector.swap(nextMergeRound);
++round;
}
assert(mergeVector.size() == 1);
// Done, rename the files to their final name
std::stringstream bwt_ss;
bwt_ss << out_prefix << bwt_extension << (USE_GZ ? ".gz" : "");
std::string bwt_final_filename = bwt_ss.str();
rename(mergeVector.front().bwt_filename.c_str(), bwt_final_filename.c_str());
std::stringstream sai_ss;
sai_ss << out_prefix << sai_extension << (USE_GZ ? ".gz" : "");
std::string sai_final_filename = sai_ss.str();
rename(mergeVector.front().sai_filename.c_str(), sai_final_filename.c_str());
}