Autres/audacity
1
0
Fork 0
mirror of https://github.com/cookiengineer/audacity synced 2025-10-26 00:03:52 +02:00
Code Issues Releases Wiki Activity

Sequence::Delete gives strong guarantee

Browse Source
This commit is contained in:
Paul Licameli
2016-11-28 21:49:00 -05:00
parent 06f6953c91
commit 63cf80d244
3 changed files with 80 additions and 76 deletions
Download Patch File Download Diff File Expand all files Collapse all files

47
src/Sequence.cpp
View File

@@ -1622,12 +1622,15 @@ void Sequence::Blockify
}
}
bool Sequence::Delete(sampleCount start, sampleCount len)
void Sequence::Delete(sampleCount start, sampleCount len)
// STRONG-GUARANTEE
{
if (len == 0)
return true;
return;
if (len < 0 || start < 0 || start >= mNumSamples)
return false;
//THROW_INCONSISTENCY_EXCEPTION
;
//TODO: add a ref-deref mechanism to SeqBlock/BlockArray so we don't have to make this a critical section.
//On-demand threads iterate over the mBlocks and the GUI thread deletes them, so for now put a mutex here over
@@ -1641,9 +1644,6 @@ bool Sequence::Delete(sampleCount start, sampleCount len)
auto sampleSize = SAMPLE_SIZE(mSampleFormat);
// Special case: if the samples to DELETE are all within a single
// block and the resulting length is not too small, perform the
// deletion within this block:
SeqBlock *pBlock;
decltype(pBlock->f->GetLength()) length;
@@ -1652,7 +1652,11 @@ bool Sequence::Delete(sampleCount start, sampleCount len)
// The maximum size that will ever be needed
const auto scratchSize = mMaxSamples + mMinSamples;
if (b0 == b1 && (length = (pBlock = &mBlock[b0])->f->GetLength()) - len >= mMinSamples) {
// Special case: if the samples to DELETE are all within a single
// block and the resulting length is not too small, perform the
// deletion within this block:
if (b0 == b1 &&
(length = (pBlock = &mBlock[b0])->f->GetLength()) - len >= mMinSamples) {
SeqBlock &b = *pBlock;
// start is within block
auto pos = ( start - b.start ).as_size_t();
@@ -1670,18 +1674,25 @@ bool Sequence::Delete(sampleCount start, sampleCount len)
// is not more than the length of the block
( pos + len ).as_size_t(), newLen - pos, true);
b = SeqBlock(
mDirManager->NewSimpleBlockFile(scratch.ptr(), newLen, mSampleFormat),
b.start
);
auto newFile =
mDirManager->NewSimpleBlockFile(scratch.ptr(), newLen, mSampleFormat);
// Don't make a duplicate array. We can still give STRONG-GUARANTEE
// if we modify only one block in place.
// use NOFAIL-GUARANTEE in remaining steps
b.f = newFile;
for (unsigned int j = b0 + 1; j < numBlocks; j++)
mBlock[j].start -= len;
mNumSamples -= len;
ConsistencyCheck(wxT("Delete - branch one"));
return true;
// This consistency check won't throw, it asserts.
// Proof that we kept consistency is not hard.
ConsistencyCheck(wxT("Delete - branch one"), false);
return;
}
// Create a NEW array of blocks
@@ -1782,14 +1793,8 @@ bool Sequence::Delete(sampleCount start, sampleCount len)
for (i = b1 + 1; i < numBlocks; i++)
newBlock.push_back(mBlock[i].Plus(-len));
// Substitute our NEW array for the old one
mBlock.swap(newBlock);
// Update total number of samples and do a consistency check.
mNumSamples -= len;
ConsistencyCheck(wxT("Delete - branch two"));
return true;
CommitChangesIfConsistent
(newBlock, mNumSamples - len, wxT("Delete - branch two"));
}
void Sequence::ConsistencyCheck(const wxChar *whereStr, bool mayThrow) const