audacia/src/SqliteSampleBlock.cpp

/**********************************************************************

Audacity: A Digital Audio Editor

SqliteSampleBlock.cpp

Paul Licameli -- split from SampleBlock.cpp and SampleBlock.h

**********************************************************************/

#include <float.h>
#include <sqlite3.h>

#include "DBConnection.h"
#include "ProjectFileIO.h"
#include "SampleFormat.h"
#include "xml/XMLTagHandler.h"

#include "SampleBlock.h" // to inherit

class SqliteSampleBlockFactory;

///\brief Implementation of @ref SampleBlock using Sqlite database
class SqliteSampleBlock final : public SampleBlock
{
public:

   explicit SqliteSampleBlock(
      const std::shared_ptr<SqliteSampleBlockFactory> &pFactory);
   ~SqliteSampleBlock() override;

   void CloseLock() override;

   void SetSamples(samplePtr src, size_t numsamples, sampleFormat srcformat);

   //! Numbers of bytes needed for 256 and for 64k summaries
   using Sizes = std::pair< size_t, size_t >;
   void Commit(Sizes sizes);

   void Delete();

   SampleBlockID GetBlockID() const override;

   size_t DoGetSamples(samplePtr dest,
                       sampleFormat destformat,
                       size_t sampleoffset,
                       size_t numsamples) override;
   sampleFormat GetSampleFormat() const;
   size_t GetSampleCount() const override;

   bool GetSummary256(float *dest, size_t frameoffset, size_t numframes) override;
   bool GetSummary64k(float *dest, size_t frameoffset, size_t numframes) override;
   double GetSumMin() const;
   double GetSumMax() const;
   double GetSumRms() const;

   /// Gets extreme values for the specified region
   MinMaxRMS DoGetMinMaxRMS(size_t start, size_t len) override;

   /// Gets extreme values for the entire block
   MinMaxRMS DoGetMinMaxRMS() const override;

   size_t GetSpaceUsage() const override;
   void SaveXML(XMLWriter &xmlFile) override;

private:
   bool IsSilent() const { return mBlockID <= 0; }
   void Load(SampleBlockID sbid);
   bool GetSummary(float *dest,
                   size_t frameoffset,
                   size_t numframes,
                   DBConnection::StatementID id,
                   const char *sql);
   size_t GetBlob(void *dest,
                  sampleFormat destformat,
                  sqlite3_stmt *stmt,
                  sampleFormat srcformat,
                  size_t srcoffset,
                  size_t srcbytes);

   enum {
      fields = 3, /* min, max, rms */
      bytesPerFrame = fields * sizeof(float),
   };
   Sizes SetSizes( size_t numsamples, sampleFormat srcformat );
   void CalcSummary(Sizes sizes);

private:
   //! This must never be called for silent blocks
   DBConnection *Conn() const;
   sqlite3 *DB() const
   {
      return Conn()->DB();
   }

   friend SqliteSampleBlockFactory;

   const std::shared_ptr<SqliteSampleBlockFactory> mpFactory;
   bool mValid{ false };
   bool mLocked = false;

   SampleBlockID mBlockID{ 0 };

   ArrayOf<char> mSamples;
   size_t mSampleBytes;
   size_t mSampleCount;
   sampleFormat mSampleFormat;

   ArrayOf<char> mSummary256;
   ArrayOf<char> mSummary64k;
   double mSumMin;
   double mSumMax;
   double mSumRms;

#if defined(WORDS_BIGENDIAN)
#error All sample block data is little endian...big endian not yet supported
#endif
};

// Silent blocks use nonpositive id values to encode a length
// and don't occupy any rows in the database; share blocks for repeatedly
// used length values
static std::map< SampleBlockID, std::shared_ptr<SqliteSampleBlock> >
   sSilentBlocks;

///\brief Implementation of @ref SampleBlockFactory using Sqlite database
class SqliteSampleBlockFactory final
   : public SampleBlockFactory
   , public std::enable_shared_from_this<SqliteSampleBlockFactory>
{
public:
   explicit SqliteSampleBlockFactory( AudacityProject &project );

   ~SqliteSampleBlockFactory() override;

   SampleBlockIDs GetActiveBlockIDs() override;

   SampleBlockPtr DoCreate(samplePtr src,
      size_t numsamples,
      sampleFormat srcformat) override;

   SampleBlockPtr DoCreateSilent(
      size_t numsamples,
      sampleFormat srcformat) override;

   SampleBlockPtr DoCreateFromXML(
      sampleFormat srcformat,
      const wxChar **attrs) override;

   BlockDeletionCallback SetBlockDeletionCallback(
      BlockDeletionCallback callback ) override;

private:
   friend SqliteSampleBlock;

   const std::shared_ptr<ConnectionPtr> mppConnection;

   // Track all blocks that this factory has created, but don't control
   // their lifetimes (so use weak_ptr)
   // (Must also use weak pointers because the blocks have shared pointers
   // to the factory and we can't have a leaky cycle of shared pointers)
   using AllBlocksMap =
      std::map< SampleBlockID, std::weak_ptr< SqliteSampleBlock > >;
   AllBlocksMap mAllBlocks;

   BlockDeletionCallback mCallback;
};

SqliteSampleBlockFactory::SqliteSampleBlockFactory( AudacityProject &project )
   : mppConnection{ ConnectionPtr::Get(project).shared_from_this() }
{
   
}

SqliteSampleBlockFactory::~SqliteSampleBlockFactory() = default;

SampleBlockPtr SqliteSampleBlockFactory::DoCreate(
   samplePtr src, size_t numsamples, sampleFormat srcformat )
{
   auto sb = std::make_shared<SqliteSampleBlock>(shared_from_this());
   sb->SetSamples(src, numsamples, srcformat);
   // block id has now been assigned
   mAllBlocks[ sb->GetBlockID() ] = sb;
   return sb;
}

auto SqliteSampleBlockFactory::GetActiveBlockIDs() -> SampleBlockIDs
{
   SampleBlockIDs result;
   for (auto end = mAllBlocks.end(), it = mAllBlocks.begin(); it != end;) {
      if (it->second.expired())
         // Tighten up the map
         it = mAllBlocks.erase(it);
      else {
         result.insert( it->first );
         ++it;
      }
   }
   return result;
}

SampleBlockPtr SqliteSampleBlockFactory::DoCreateSilent(
   size_t numsamples, sampleFormat )
{
   auto id = -static_cast< SampleBlockID >(numsamples);
   auto &result = sSilentBlocks[ id ];
   if ( !result ) {
      result = std::make_shared<SqliteSampleBlock>(nullptr);
      result->mBlockID = id;

      // Ignore the supplied sample format
      result->SetSizes(numsamples, floatSample);
      result->mValid = true;
   }

   return result;
}


SampleBlockPtr SqliteSampleBlockFactory::DoCreateFromXML(
   sampleFormat srcformat, const wxChar **attrs )
{
   std::shared_ptr<SampleBlock> sb;

   int found = 0;

   // loop through attrs, which is a null-terminated list of attribute-value pairs
   while(*attrs)
   {
      const wxChar *attr = *attrs++;
      const wxChar *value = *attrs++;

      if (!value)
      {
         break;
      }

      const wxString strValue = value;   // promote string, we need this for all
      double dblValue;
      long long nValue;

      if (wxStrcmp(attr, wxT("blockid")) == 0 &&
         XMLValueChecker::IsGoodInt(strValue) && strValue.ToLongLong(&nValue))
      {
         if (nValue <= 0) {
            sb = DoCreateSilent( -nValue, floatSample );
         }
         else {
            // First see if this block id was previously loaded
            auto &wb = mAllBlocks[ nValue ];
            auto pb = wb.lock();
            if (pb)
               // Reuse the block
               sb = pb;
            else {
               // First sight of this id
               auto ssb =
                  std::make_shared<SqliteSampleBlock>(shared_from_this());
               wb = ssb;
               sb = ssb;
               ssb->mSampleFormat = srcformat;
               // This may throw database errors
               // It initializes the rest of the fields
               ssb->Load((SampleBlockID) nValue);
            }
         }
         found++;
      }
   }

  // Were all attributes found?
   if (found != 1)
   {
      return nullptr;
   }

   return sb;
}

auto SqliteSampleBlockFactory::SetBlockDeletionCallback(
   BlockDeletionCallback callback ) -> BlockDeletionCallback
{
   auto result = mCallback;
   mCallback = std::move( callback );
   return result;
}

SqliteSampleBlock::SqliteSampleBlock(
   const std::shared_ptr<SqliteSampleBlockFactory> &pFactory)
:  mpFactory(pFactory)
{
   mSampleFormat = floatSample;
   mSampleBytes = 0;
   mSampleCount = 0;

   mSumMin = 0.0;
   mSumMax = 0.0;
   mSumRms = 0.0;
}

SqliteSampleBlock::~SqliteSampleBlock()
{
   auto &callback = mpFactory->mCallback;
   if (callback)
      GuardedCall( [&]{ callback( *this ); } );

   if (IsSilent()) {
      // The block object was constructed but failed to Load() or Commit().
      // Or it's a silent block with no row in the database.
      // Just let the stack unwind.  Don't violate the assertion in
      // Delete(), which may do odd recursive things in debug builds when it
      // yields to the UI to put up a dialog, but then dispatches timer
      // events that try again to finish recording.
      return;
   }

   // See ProjectFileIO::Bypass() for a description of mIO.mBypass
   if (!mLocked && !Conn()->ShouldBypass())
   {
      // In case Delete throws, don't let an exception escape a destructor,
      // but we can still enqueue the delayed handler so that an error message
      // is presented to the user.
      // The failure in this case may be a less harmful waste of space in the
      // database, which should not cause aborting of the attempted edit.
      GuardedCall( [this]{ Delete(); } );
   }
}

DBConnection *SqliteSampleBlock::Conn() const
{
   auto &pConnection = mpFactory->mppConnection->mpConnection;
   if (!pConnection) {
      throw SimpleMessageBoxException
      {
         XO("Failed to open the project's database"),
         XO("Warning"),
         "Error:_Disk_full_or_not_writable"
      };
   }
   return pConnection.get();
}

void SqliteSampleBlock::CloseLock()
{
   mLocked = true;
}

SampleBlockID SqliteSampleBlock::GetBlockID() const
{
   return mBlockID;
}

sampleFormat SqliteSampleBlock::GetSampleFormat() const
{
   return mSampleFormat;
}

size_t SqliteSampleBlock::GetSampleCount() const
{
   return mSampleCount;
}

size_t SqliteSampleBlock::DoGetSamples(samplePtr dest,
                                     sampleFormat destformat,
                                     size_t sampleoffset,
                                     size_t numsamples)
{
   if (IsSilent()) {
      ClearSamples(dest, destformat, sampleoffset, numsamples);
      return numsamples;
   }

   // Prepare and cache statement...automatically finalized at DB close
   sqlite3_stmt *stmt = Conn()->Prepare(DBConnection::GetSamples,
      "SELECT samples FROM sampleblocks WHERE blockid = ?1;");

   return GetBlob(dest,
                  destformat,
                  stmt,
                  mSampleFormat,
                  sampleoffset * SAMPLE_SIZE(mSampleFormat),
                  numsamples * SAMPLE_SIZE(mSampleFormat)) / SAMPLE_SIZE(mSampleFormat);
}

void SqliteSampleBlock::SetSamples(samplePtr src,
                                   size_t numsamples,
                                   sampleFormat srcformat)
{
   auto sizes = SetSizes(numsamples, srcformat);
   mSamples.reinit(mSampleBytes);
   memcpy(mSamples.get(), src, mSampleBytes);

   CalcSummary( sizes );

   Commit( sizes );
}

bool SqliteSampleBlock::GetSummary256(float *dest,
                                      size_t frameoffset,
                                      size_t numframes)
{
   return GetSummary(dest, frameoffset, numframes, DBConnection::GetSummary256,
      "SELECT summary256 FROM sampleblocks WHERE blockid = ?1;");
}

bool SqliteSampleBlock::GetSummary64k(float *dest,
                                      size_t frameoffset,
                                      size_t numframes)
{
   return GetSummary(dest, frameoffset, numframes, DBConnection::GetSummary64k,
      "SELECT summary64k FROM sampleblocks WHERE blockid = ?1;");
}

bool SqliteSampleBlock::GetSummary(float *dest,
                                   size_t frameoffset,
                                   size_t numframes,
                                   DBConnection::StatementID id,
                                   const char *sql)
{
   // Non-throwing, it returns true for success
   bool silent = IsSilent();
   if (!silent) {
      // Not a silent block
      try {
         // Prepare and cache statement...automatically finalized at DB close
         auto stmt = Conn()->Prepare(id, sql);
         // Note GetBlob returns a size_t, not a bool
         GetBlob(dest,
                     floatSample,
                     stmt,
                     floatSample,
                     frameoffset * fields * SAMPLE_SIZE(floatSample),
                     numframes * fields * SAMPLE_SIZE(floatSample));
         return true;
      }
      catch ( const AudacityException & ) {
      }
   }
   memset(dest, 0, 3 * numframes * sizeof( float ));
   // Return true for success only if we didn't catch
   return silent;
}

double SqliteSampleBlock::GetSumMin() const
{
   return mSumMin;
}

double SqliteSampleBlock::GetSumMax() const
{
   return mSumMax;
}

double SqliteSampleBlock::GetSumRms() const
{
   return mSumRms;
}

/// Retrieves the minimum, maximum, and maximum RMS of the
/// specified sample data in this block.
///
/// @param start The offset in this block where the region should begin
/// @param len   The number of samples to include in the region
MinMaxRMS SqliteSampleBlock::DoGetMinMaxRMS(size_t start, size_t len)
{
   if (IsSilent())
      return {};

   float min = FLT_MAX;
   float max = -FLT_MAX;
   float sumsq = 0;

   if (!mValid)
   {
      Load(mBlockID);
   }

   if (start < mSampleCount)
   {
      len = std::min(len, mSampleCount - start);

      // TODO: actually use summaries
      SampleBuffer blockData(len, floatSample);
      float *samples = (float *) blockData.ptr();

      size_t copied = DoGetSamples((samplePtr) samples, floatSample, start, len);
      for (size_t i = 0; i < copied; ++i, ++samples)
      {
         float sample = *samples;

         if (sample > max)
         {
            max = sample;
         }

         if (sample < min)
         {
            min = sample;
         }

         sumsq += (sample * sample);
      }
   }

   return { min, max, (float) sqrt(sumsq / len) };
}

/// Retrieves the minimum, maximum, and maximum RMS of this entire
/// block.  This is faster than the other GetMinMax function since
/// these values are already computed.
MinMaxRMS SqliteSampleBlock::DoGetMinMaxRMS() const
{
   return { (float) mSumMin, (float) mSumMax, (float) mSumRms };
}

size_t SqliteSampleBlock::GetSpaceUsage() const
{
   if (IsSilent())
      return 0;
   else
      return ProjectFileIO::GetDiskUsage(Conn(), mBlockID);
}

size_t SqliteSampleBlock::GetBlob(void *dest,
                                  sampleFormat destformat,
                                  sqlite3_stmt *stmt,
                                  sampleFormat srcformat,
                                  size_t srcoffset,
                                  size_t srcbytes)
{
   auto db = DB();

   wxASSERT(!IsSilent());

   if (!mValid)
   {
      Load(mBlockID);
   }

   int rc;
   size_t minbytes = 0;

   // Bind statement parameters
   // Might return SQLITE_MISUSE which means it's our mistake that we violated
   // preconditions; should return SQL_OK which is 0
   if (sqlite3_bind_int64(stmt, 1, mBlockID))
   {
      wxASSERT_MSG(false, wxT("Binding failed...bug!!!"));
   }

   // Execute the statement
   rc = sqlite3_step(stmt);
   if (rc != SQLITE_ROW)
   {
      wxLogDebug(wxT("SqliteSampleBlock::GetBlob - SQLITE error %s"), sqlite3_errmsg(db));

      // Clear statement bindings and rewind statement
      sqlite3_clear_bindings(stmt);
      sqlite3_reset(stmt);

      // Just showing the user a simple message, not the library error too
      // which isn't internationalized
      Conn()->ThrowException( false );
   }

   // Retrieve returned data
   samplePtr src = (samplePtr) sqlite3_column_blob(stmt, 0);
   size_t blobbytes = (size_t) sqlite3_column_bytes(stmt, 0);

   srcoffset = std::min(srcoffset, blobbytes);
   minbytes = std::min(srcbytes, blobbytes - srcoffset);

   if (srcoffset != 0)
   {
      srcoffset += 0;
   }

   CopySamples(src + srcoffset,
               srcformat,
               (samplePtr) dest,
               destformat,
               minbytes / SAMPLE_SIZE(srcformat));

   dest = ((samplePtr) dest) + minbytes;

   if (srcbytes - minbytes)
   {
      memset(dest, 0, srcbytes - minbytes);
   }

   // Clear statement bindings and rewind statement
   sqlite3_clear_bindings(stmt);
   sqlite3_reset(stmt);

   return srcbytes;
}

void SqliteSampleBlock::Load(SampleBlockID sbid)
{
   auto db = DB();
   int rc;

   wxASSERT(sbid > 0);

   mValid = false;
   mSampleCount = 0;
   mSampleBytes = 0;
   mSumMin = FLT_MAX;
   mSumMax = -FLT_MAX;
   mSumMin = 0.0;

   // Prepare and cache statement...automatically finalized at DB close
   sqlite3_stmt *stmt = Conn()->Prepare(DBConnection::LoadSampleBlock,
      "SELECT sampleformat, summin, summax, sumrms,"
      "       length(samples)"
      "  FROM sampleblocks WHERE blockid = ?1;");

   // Bind statement parameters
   // Might return SQLITE_MISUSE which means it's our mistake that we violated
   // preconditions; should return SQL_OK which is 0
   if (sqlite3_bind_int64(stmt, 1, sbid))
   {
      wxASSERT_MSG(false, wxT("Binding failed...bug!!!"));
   }

   // Execute the statement
   rc = sqlite3_step(stmt);
   if (rc != SQLITE_ROW)
   {
      wxLogDebug(wxT("SqliteSampleBlock::Load - SQLITE error %s"), sqlite3_errmsg(db));

      // Clear statement bindings and rewind statement
      sqlite3_clear_bindings(stmt);
      sqlite3_reset(stmt);

      // Just showing the user a simple message, not the library error too
      // which isn't internationalized
      Conn()->ThrowException( false );
   }

   // Retrieve returned data
   mBlockID = sbid;
   mSampleFormat = (sampleFormat) sqlite3_column_int(stmt, 0);
   mSumMin = sqlite3_column_double(stmt, 1);
   mSumMax = sqlite3_column_double(stmt, 2);
   mSumRms = sqlite3_column_double(stmt, 3);
   mSampleBytes = sqlite3_column_int(stmt, 4);
   mSampleCount = mSampleBytes / SAMPLE_SIZE(mSampleFormat);

   // Clear statement bindings and rewind statement
   sqlite3_clear_bindings(stmt);
   sqlite3_reset(stmt);

   mValid = true;
}

void SqliteSampleBlock::Commit(Sizes sizes)
{
   const auto mSummary256Bytes = sizes.first;
   const auto mSummary64kBytes = sizes.second;

   auto db = DB();
   int rc;

   // Prepare and cache statement...automatically finalized at DB close
   sqlite3_stmt *stmt = Conn()->Prepare(DBConnection::InsertSampleBlock,
      "INSERT INTO sampleblocks (sampleformat, summin, summax, sumrms,"
      "                          summary256, summary64k, samples)"
      "                         VALUES(?1,?2,?3,?4,?5,?6,?7);");

   // Bind statement parameters
   // Might return SQLITE_MISUSE which means it's our mistake that we violated
   // preconditions; should return SQL_OK which is 0
   if (sqlite3_bind_int(stmt, 1, mSampleFormat) ||
       sqlite3_bind_double(stmt, 2, mSumMin) ||
       sqlite3_bind_double(stmt, 3, mSumMax) ||
       sqlite3_bind_double(stmt, 4, mSumRms) ||
       sqlite3_bind_blob(stmt, 5, mSummary256.get(), mSummary256Bytes, SQLITE_STATIC) ||
       sqlite3_bind_blob(stmt, 6, mSummary64k.get(), mSummary64kBytes, SQLITE_STATIC) ||
       sqlite3_bind_blob(stmt, 7, mSamples.get(), mSampleBytes, SQLITE_STATIC))
   {
      wxASSERT_MSG(false, wxT("Binding failed...bug!!!"));
   }
 
   // Execute the statement
   rc = sqlite3_step(stmt);
   if (rc != SQLITE_DONE)
   {
      wxLogDebug(wxT("SqliteSampleBlock::Commit - SQLITE error %s"), sqlite3_errmsg(db));

      // Clear statement bindings and rewind statement
      sqlite3_clear_bindings(stmt);
      sqlite3_reset(stmt);

      // Just showing the user a simple message, not the library error too
      // which isn't internationalized
      Conn()->ThrowException( true );
   }

   // Retrieve returned data
   mBlockID = sqlite3_last_insert_rowid(db);

   // Reset local arrays
   mSamples.reset();
   mSummary256.reset();
   mSummary64k.reset();

   // Clear statement bindings and rewind statement
   sqlite3_clear_bindings(stmt);
   sqlite3_reset(stmt);

   mValid = true;
}

void SqliteSampleBlock::Delete()
{
   auto db = DB();
   int rc;

   wxASSERT(!IsSilent());

   // Prepare and cache statement...automatically finalized at DB close
   sqlite3_stmt *stmt = Conn()->Prepare(DBConnection::DeleteSampleBlock,
      "DELETE FROM sampleblocks WHERE blockid = ?1;");

   // Bind statement parameters
   // Might return SQLITE_MISUSE which means it's our mistake that we violated
   // preconditions; should return SQL_OK which is 0
   if (sqlite3_bind_int64(stmt, 1, mBlockID))
   {
      wxASSERT_MSG(false, wxT("Binding failed...bug!!!"));
   }

   // Execute the statement
   rc = sqlite3_step(stmt);
   if (rc != SQLITE_DONE)
   {
      wxLogDebug(wxT("SqliteSampleBlock::Load - SQLITE error %s"), sqlite3_errmsg(db));

      // Clear statement bindings and rewind statement
      sqlite3_clear_bindings(stmt);
      sqlite3_reset(stmt);

      // Just showing the user a simple message, not the library error too
      // which isn't internationalized
      Conn()->ThrowException( true );
   }

   // Clear statement bindings and rewind statement
   sqlite3_clear_bindings(stmt);
   sqlite3_reset(stmt);
}

void SqliteSampleBlock::SaveXML(XMLWriter &xmlFile)
{
   xmlFile.WriteAttr(wxT("blockid"), mBlockID);
}

auto SqliteSampleBlock::SetSizes(
   size_t numsamples, sampleFormat srcformat ) -> Sizes
{
   mSampleFormat = srcformat;
   mSampleCount = numsamples;
   mSampleBytes = mSampleCount * SAMPLE_SIZE(mSampleFormat);

   int frames64k = (mSampleCount + 65535) / 65536;
   int frames256 = frames64k * 256;
   return { frames256 * bytesPerFrame, frames64k * bytesPerFrame };
}

/// Calculates summary block data describing this sample data.
///
/// This method also has the side effect of setting the mSumMin,
/// mSumMax, and mSumRms members of this class.
///
void SqliteSampleBlock::CalcSummary(Sizes sizes)
{
   const auto mSummary256Bytes = sizes.first;
   const auto mSummary64kBytes = sizes.second;

   Floats samplebuffer;
   float *samples;

   if (mSampleFormat == floatSample)
   {
      samples = (float *) mSamples.get();
   }
   else
   {
      samplebuffer.reinit((unsigned) mSampleCount);
      CopySamples(mSamples.get(),
                  mSampleFormat,
                  (samplePtr) samplebuffer.get(),
                  floatSample,
                  mSampleCount);
      samples = samplebuffer.get();
   }
   
   mSummary256.reinit(mSummary256Bytes);
   mSummary64k.reinit(mSummary64kBytes);

   float *summary256 = (float *) mSummary256.get();
   float *summary64k = (float *) mSummary64k.get();

   float min;
   float max;
   float sumsq;
   double totalSquares = 0.0;
   double fraction = 0.0;

   // Recalc 256 summaries
   int sumLen = (mSampleCount + 255) / 256;
   int summaries = 256;

   for (int i = 0; i < sumLen; ++i)
   {
      min = samples[i * 256];
      max = samples[i * 256];
      sumsq = min * min;

      int jcount = 256;
      if (jcount > mSampleCount - i * 256)
      {
         jcount = mSampleCount - i * 256;
         fraction = 1.0 - (jcount / 256.0);
      }

      for (int j = 1; j < jcount; ++j)
      {
         float f1 = samples[i * 256 + j];
         sumsq += f1 * f1;

         if (f1 < min)
         {
            min = f1;
         }
         else if (f1 > max)
         {
            max = f1;
         }
      }

      totalSquares += sumsq;

      summary256[i * fields] = min;
      summary256[i * fields + 1] = max;
      // The rms is correct, but this may be for less than 256 samples in last loop.
      summary256[i * fields + 2] = (float) sqrt(sumsq / jcount);
   }

   for (int i = sumLen, frames256 = mSummary256Bytes / bytesPerFrame;
        i < frames256; ++i)
   {
      // filling in the remaining bits with non-harming/contributing values
      // rms values are not "non-harming", so keep count of them:
      summaries--;
      summary256[i * fields] = FLT_MAX;        // min
      summary256[i * fields + 1] = -FLT_MAX;   // max
      summary256[i * fields + 2] = 0.0f;       // rms
   }

   // Calculate now while we can do it accurately
   mSumRms = sqrt(totalSquares / mSampleCount);

   // Recalc 64K summaries
   sumLen = (mSampleCount + 65535) / 65536;

   for (int i = 0; i < sumLen; ++i)
   {
      min = summary256[3 * i * 256];
      max = summary256[3 * i * 256 + 1];
      sumsq = summary256[3 * i * 256 + 2];
      sumsq *= sumsq;

      for (int j = 1; j < 256; ++j)
      {
         // we can overflow the useful summary256 values here, but have put
         // non-harmful values in them
         if (summary256[3 * (i * 256 + j)] < min)
         {
            min = summary256[3 * (i * 256 + j)];
         }

         if (summary256[3 * (i * 256 + j) + 1] > max)
         {
            max = summary256[3 * (i * 256 + j) + 1];
         }

         float r1 = summary256[3 * (i * 256 + j) + 2];
         sumsq += r1 * r1;
      }

      double denom = (i < sumLen - 1) ? 256.0 : summaries - fraction;
      float rms = (float) sqrt(sumsq / denom);

      summary64k[i * fields] = min;
      summary64k[i * fields + 1] = max;
      summary64k[i * fields + 2] = rms;
   }

   for (int i = sumLen, frames64k = mSummary64kBytes / bytesPerFrame;
        i < frames64k; ++i)
   {
      wxASSERT_MSG(false, wxT("Out of data for mSummaryInfo"));   // Do we ever get here?

      summary64k[i * fields] = 0.0f;     // probably should be FLT_MAX, need a test case
      summary64k[i * fields + 1] = 0.0f; // probably should be -FLT_MAX, need a test case
      summary64k[i * fields + 2] = 0.0f; // just padding
   }

   // Recalc block-level summary (mRMS already calculated)
   min = summary64k[0];
   max = summary64k[1];

   for (int i = 1; i < sumLen; ++i)
   {
      if (summary64k[i * fields] < min)
      {
         min = summary64k[i * fields];
      }

      if (summary64k[i * fields + 1] > max)
      {
         max = summary64k[i * fields + 1];
      }
   }

   mSumMin = min;
   mSumMax = max;
}

// Inject our database implementation at startup
static struct Injector
{
   Injector()
   {
      // Do this some time before the first project is created
      (void) SampleBlockFactory::RegisterFactoryFactory(
         []( AudacityProject &project )
         {
            return std::make_shared<SqliteSampleBlockFactory>( project );
         }
      );
   }
} injector;