public void RemoveEmptyChanges()
{
int totalChanges = changes.Count;
Logger.LogInformation("Removing empty changes from {count} changes", totalChanges);
int number = 0;
for (int index = 0; index < changes.Count; index++)
{
number++;
if (number % 1000 == 0)
{
Logger.LogInformation("Checking if change {number} of {total} is empty", number, totalChanges);
}
var change = changes[index];
if (change.HasChanges())
{
continue;
}
for (int i = index - 1; 0 <= i; i--)
{
var previousChange = changes[i];
if (previousChange.Branch != change.Branch)
{
continue;
}
ChangeSet nextChange = null;
int indexNext = index;
while (true)
{
indexNext++;
if (changes.Count <= indexNext)
{
break;
}
var nextChangeCandidate = changes[indexNext];
if (nextChangeCandidate.Branch != change.Branch)
{
continue;
}
nextChange = nextChangeCandidate;
break;
}
ReplaceBranchedFrom(change, previousChange);
if (nextChange != null)
{
foreach (var br in change.GetBranchedFrom())
{
nextChange.AddBranchedFrom(br);
}
// Move over comments about dirs as otherwise they will be lost.
int dirIndex = 0;
foreach (var dirComment in change.Changes)
{
if (dirComment.Type != ChangeSet.ChangeType.DIRECTORY_COMMENT)
{
throw new Exception($"Tryng to move non-dir comment change {dirComment} for {change}");
}
nextChange.InsertDirectoryComment(dirIndex, dirComment.FileName, dirComment.Version as DirectoryElementBranchVersion);
dirIndex++;
}
}
changes.RemoveAt(index);
// force a check for the entry that replaced it
index--;
Logger.LogDebug("Removing {change} and replacing with {previousChange}", change, previousChange);
break;
}
}
RebuildForwardMerges();
RebuildIndexLookup();
Logger.LogInformation("After removing empty change we got {count} changes", changes.Count);
}
// Assuming A and C belongs to different branches, B is on the same
// branch as A and D is on the same branch as C we merge the following
// commit graph
// A
// /|
// C B
// |/
// D
// to create the graph
// A'
// /
// C'
// with A'=A+B and C'=C+D
public void SquashMergeDiamonds()
{
int totalChanges = changes.Count;
Logger.LogInformation("Checking if any merge diamonds could be squashed out of {count} changes", totalChanges);
bool changed;
int number = 0;
do
{
changed = false;
foreach (var changeA in changes.ToList())
{
if (changeA.GetBranchedFrom().Count != 1)
{
continue;
}
int indexA = indexLookup[changeA];
for (int indexB = indexA - 1; 0 <= indexB; indexB--)
{
var changeB = changes[indexB];
if (changeB.Branch != changeA.Branch)
{
continue;
}
if (!Squashable(changeB, changeA))
{
break;
}
if (forwardMerges.ContainsKey(changeB) || changeB.GetBranchedFrom().Count != 1)
{
break;
}
ChangeSet changeC = changeA.GetBranchedFrom().First();
if (forwardMerges[changeC].Count != 1)
{
break;
}
ChangeSet changeD = null;
int indexD = indexLookup[changeC];
while (true)
{
indexD--;
if (indexD < 0)
{
break;
}
var changeDCandidate = changes[indexD];
if (changeDCandidate.Branch != changeC.Branch)
{
continue;
}
if (!Squashable(changeDCandidate, changeC))
{
break;
}
if (changeB.GetBranchedFrom().First() != changeDCandidate || forwardMerges[changeDCandidate].Count != 1)
{
break;
}
changeD = changeDCandidate;
break;
}
if (changeD == null)
{
break;
}
ChangeSet aPrime = changeB.Plus(changeA);
ChangeSet cPrime = changeD.Plus(changeC);
// changeA is always last.
changes.RemoveAt(indexA);
changes.Insert(indexA, aPrime);
int indexC = indexLookup[changeC];
if (indexC < indexB)
{
changes.RemoveAt(indexB);
changes.RemoveAt(indexC);
changes.Insert(indexC, cPrime);
}
else
{
changes.RemoveAt(indexC);
changes.Insert(indexC, cPrime);
changes.RemoveAt(indexB);
}
// changeD is always first.
changes.RemoveAt(indexD);
aPrime.AddBranchedFrom(cPrime);
ReplaceBranchedFrom(changeA, aPrime);
ReplaceBranchedFrom(changeC, cPrime);
changed = true;
RebuildIndexLookup();
RebuildForwardMerges();
number++;
if (number % 500 == 0)
{
Logger.LogInformation("Squashed {number} merge diamonds so far ({total} maximum possible", number, totalChanges);
}
Logger.LogDebug("Squashing merge diamond {changeA} + {changeB} => {aPrime}; {changeC} + {changeD} => {cPrime}", changeA, changeB, aPrime, changeC, changeD, cPrime);
break;
}
if (changed)
{
break;
}
}
} while (changed);
Logger.LogInformation("After squashing merge diamonds we got {count} changes", changes.Count);
}
