Method ComputeRecoveryBlockCount

src/commandline.cpp:1348–1435

Determine how many recovery blocks to create based on the source block count and the requested level of redundancy.

// Determine how many recovery blocks to create based on the source block
// count and the requested level of redundancy.
bool CommandLine::ComputeRecoveryBlockCount(u32 *recoveryblockcount,
					    u32 sourceblockcount,
					    u64 blocksize,
					    u32 firstblock,
					    Scheme recoveryfilescheme,
					    u32 recoveryfilecount,
					    bool recoveryblockcountset,
					    u32 redundancy,
					    u64 redundancysize,
					    u64 largestfilesize)
{
  if (recoveryblockcountset) {
    // no need to assign value.
    // pass through, so that value can be checked below.
  }
  else if (redundancy > 0)
  {
    // count is the number of input blocks

    // Determine recoveryblockcount
    *recoveryblockcount = (sourceblockcount * redundancy + 50) / 100;
  }
  else if (redundancysize > 0)
  {
    const u64 overhead_per_recovery_file = sourceblockcount * (u64) 21;
    const u64 recovery_packet_size = blocksize + (u64) 70;
    if (recoveryfilecount == 0)
    {
      u32 estimatedFileCount = 15;
      u64 overhead = estimatedFileCount * overhead_per_recovery_file;
      u32 estimatedrecoveryblockcount;
      if (overhead > redundancysize)
      {
        estimatedrecoveryblockcount = 1;  // at least 1
      }
      else
      {
	estimatedrecoveryblockcount = (u32)((redundancysize - overhead) / recovery_packet_size);
      }

      // recoveryfilecount assigned below.
      bool success = ComputeRecoveryFileCount(std::cout,
					      std::cerr,
					      &recoveryfilecount,
					      recoveryfilescheme,
					      estimatedrecoveryblockcount,
					      largestfilesize,
					      blocksize);
      if (!success) {
	return false;
      }
    }

    const u64 overhead = recoveryfilecount * overhead_per_recovery_file;
    if (overhead > redundancysize)
    {
      *recoveryblockcount = 1;  // at least 1
    }