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Optimized block offset calculation for partimage and partclone from

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O(n²) to O(log n).
This commit is contained in:
Natalia Portillo
2017-09-21 19:09:27 +01:00
parent 90a39696ff
commit 180359e86b
2 changed files with 87 additions and 22 deletions
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58
DiscImageChef.DiscImages/Partimage.cs
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@@ -40,6 +40,7 @@ using DiscImageChef.CommonTypes;
using DiscImageChef.Console;
using DiscImageChef.Filters;
using System.Text;
using Extents;
namespace DiscImageChef.DiscImages
{
@@ -269,6 +270,9 @@ namespace DiscImageChef.DiscImages
const uint MaxCacheSize = 16777216;
uint maxCachedSectors = MaxCacheSize / 512;
ExtentsULong extents;
Dictionary<ulong, ulong> extentsOff;
public Partimage()
{
Name = "Partimage disk image";
@@ -475,6 +479,42 @@ namespace DiscImageChef.DiscImages
if(!magic.Equals(MAGIC_BEGIN_TAIL))
throw new ImageNotSupportedException("Cannot find tail. Multiple volumes are not supported or image is corrupt.");
DicConsole.DebugWriteLine("Partimage plugin", "Filling extents");
DateTime start = DateTime.Now;
extents = new ExtentsULong();
extentsOff = new Dictionary<ulong, ulong>();
bool current = (bitmap[0] & 1 << (int)(0 % 8)) != 0;
ulong blockOff = 0;
ulong extentStart = 0;
for(ulong i = 1; i <= localHeader.qwBlocksCount; i++)
{
bool next = (bitmap[i / 8] & 1 << (int)(i % 8)) != 0;
// Flux
if(next != current)
{
// Next is used
if(next)
{
extentStart = i;
extentsOff.Add(i, ++blockOff);
}
else
{
extents.Add(extentStart, i);
extentsOff.TryGetValue(extentStart, out ulong foo);
}
}
if(next && current)
blockOff++;
current = next;
}
DateTime end = DateTime.Now;
DicConsole.DebugWriteLine("Partimage plugin", "Took {0} seconds to fill extents", (end - start).TotalSeconds);
sectorCache = new Dictionary<ulong, byte[]>();
ImageInfo.imageCreationTime = dateCreate;
@@ -492,21 +532,11 @@ namespace DiscImageChef.DiscImages
return true;
}
bool IsEmpty(ulong sectorAddress)
{
return (bitmap[sectorAddress / 8] & 1 << (int)(sectorAddress % 8)) == 0;
}
// TODO: Find a way to optimize this, it's insanely slow!
ulong BlockOffset(ulong sectorAddress)
{
ulong blockOff = 0;
for(ulong i = 0; i < sectorAddress; i++)
{
if(!IsEmpty(i))
blockOff++;
}
return blockOff;
extents.GetStart(sectorAddress, out ulong extentStart);
extentsOff.TryGetValue(extentStart, out ulong extentStartingOffset);
return extentStartingOffset + (sectorAddress - extentStart);
}
public override byte[] ReadSector(ulong sectorAddress)
@@ -514,7 +544,7 @@ namespace DiscImageChef.DiscImages
if(sectorAddress > ImageInfo.sectors - 1)
throw new ArgumentOutOfRangeException(nameof(sectorAddress), string.Format("Sector address {0} not found", sectorAddress));
if(IsEmpty(sectorAddress))
if((bitmap[sectorAddress / 8] & 1 << (int)(sectorAddress % 8)) == 0)
return new byte[ImageInfo.sectorSize];
byte[] sector;