| public TryAllocate ( long length, IMemoryBlock &allocatedBlock ) : bool | ||
| length | long | Length, in bytes, of memory block |
| allocatedBlock | IMemoryBlock | Allocated memory block |
| return | bool | |
/// <summary>
/// Creates a buffer of the specified size, filled with the contents of a specified byte array
/// </summary>
/// <param name="size">Buffer size, in bytes</param>
/// <param name="filledWith">Byte array to copy to buffer</param>
/// <returns>IBuffer object of requested size</returns>
public IBuffer GetBuffer(long size, byte[] filledWith)
{
if (size < 0) throw new ArgumentException("size must be greater than 0");
//TODO: If size is larger than 16 * SlabSize (or MaxNumberOfSegments * SlabSize) then throw exception saying you can't have a buffer greater than 16 times Slab size
//Write test for this
//Make sure filledWith can fit into the requested buffer, so that we do not allocate a buffer and then
//an exception is thrown (when IBuffer.FillWith() is called) before the buffer is returned.
if (filledWith != null)
{
if (filledWith.LongLength > size) throw new ArgumentException("Length of filledWith array cannot be larger than desired buffer size");
if (filledWith.LongLength == 0) filledWith = null;
//TODO: Write test that will test that IBuffer.FillWith() doesn't throw an exception (and that buffers aren't allocated) in this method
}
if (size == 0)
{
//Return an empty buffer
return new ManagedBuffer(firstSlab);
}
List<IMemoryBlock> allocatedBlocks = new List<IMemoryBlock>();
//TODO: Consider the performance penalty involved in making the try-catch below a constrained region
//RuntimeHelpers.PrepareConstrainedRegions();
try
{
IMemorySlab[] slabArr;
long allocdLengthTally = 0;
if (GetSingleSlabPool())
{
//Optimization: Chances are that there'll be just one slab in a pool, so access it directly
//and avoid the lock statement involved while creating an array of slabs.
//Note that even if singleSlabPool is inaccurate, this method will still work properly.
//The optimization is effective because singleSlabPool will be accurate majority of the time.
slabArr = new IMemorySlab[] { firstSlab };
allocdLengthTally = TryAllocateBlocksInSlabs(size, MAX_SEGMENTS_PER_BUFFER, slabArr, ref allocatedBlocks);
if (allocdLengthTally == size)
{
//We got the entire length we are looking for, so leave
return GetFilledBuffer(allocatedBlocks, filledWith);
}
SetSingleSlabPool(false); // Slab count will soon be incremented
}
else
{
lock (syncSlabList)
{
slabArr = slabs.ToArray();
}
allocdLengthTally = TryAllocateBlocksInSlabs(size, MAX_SEGMENTS_PER_BUFFER, slabArr, ref allocatedBlocks);
if (allocdLengthTally == size)
{
//We got the entire length we are looking for, so leave
return GetFilledBuffer(allocatedBlocks, filledWith);
}
}
//Try to create new slab
lock (syncNewSlab)
{
//Look again for free block
lock (syncSlabList)
{
slabArr = slabs.ToArray();
}
allocdLengthTally += TryAllocateBlocksInSlabs(size - allocdLengthTally, MAX_SEGMENTS_PER_BUFFER - allocatedBlocks.Count, slabArr, ref allocatedBlocks);
if (allocdLengthTally == size)
{
//found it -- leave
return GetFilledBuffer(allocatedBlocks, filledWith);
}
List<IMemorySlab> newSlabList = new List<IMemorySlab>();
do
{
//Unable to find available free space, so create new slab
MemorySlab newSlab = new MemorySlab(slabSize, this);
IMemoryBlock allocdBlk;
if (slabSize > size - allocdLengthTally)
{
//Allocate remnant
newSlab.TryAllocate(size - allocdLengthTally, out allocdBlk);
}
else
{
//Allocate entire slab
newSlab.TryAllocate(slabSize, out allocdBlk);
}
newSlabList.Add(newSlab);
allocatedBlocks.Add(allocdBlk);
allocdLengthTally += allocdBlk.Length;
}
while (allocdLengthTally < size);
lock (syncSlabList)
{
//Add new slabs to collection
slabs.AddRange(newSlabList);
//Add extra slabs as requested in object properties
for (int i = 0; i < subsequentSlabs - 1; i++)
{
slabs.Add(new MemorySlab(slabSize, this));
}
}
}
return GetFilledBuffer(allocatedBlocks, filledWith);
}
catch
{
//OOM, Thread abort exceptions and other ugly things can happen so roll back any allocated blocks.
//This will prevent a limbo situation where those blocks are allocated but caller is unaware and can't deallocate them.
//NOTE: This try-catch block should not be within a lock as it calls MemorySlab.Free which takes locks,
//and in turn calls BufferPool.TryFreeSlabs which takes other locks and can lead to a dead-lock/race condition.
//TODO: Write rollback test.
for (int b = 0; b < allocatedBlocks.Count; b++)
{
allocatedBlocks[b].Slab.Free(allocatedBlocks[b]);
}
throw;
}
}
/// <summary>
/// Creates a buffer of the specified size
/// </summary>
/// <param name="size">Buffer size, in bytes</param>
/// <returns>IBuffer object of requested size</returns>
public IBuffer GetBuffer(long size)
{
if (size < 0) throw new ArgumentException("Length must be greater than 0");
if (size == 0) return new ManagedBuffer(firstSlab); //Return an empty buffer
IMemoryBlock allocatedBlock;
IMemorySlab[] slabArr;
if (singleSlabPool == -1)
{
//Optimization: Chances are that there'll be just one slab in a pool, so access it directly
//and avoid the lock statement involved while creating an array of slabs.
//Note that even if singleSlabPool is inaccurate, this method will still work properly.
//The optimization is effective because singleSlabPool will be accurate majority of the time.
slabArr = new IMemorySlab[] { firstSlab };
if (TryAllocateBlockInSlabs(size, slabArr, out allocatedBlock))
{
return new ManagedBuffer(allocatedBlock);
}
Interlocked.Exchange(ref singleSlabPool, 0); // Slab count will soon be incremented
}
else
{
lock (sync_slabList)
{
slabArr = slabs.ToArray();
}
if (TryAllocateBlockInSlabs(size, slabArr, out allocatedBlock))
{
return new ManagedBuffer(allocatedBlock);
}
}
lock (sync_newSlab)
{
//Look again for free block
lock (sync_slabList)
{
slabArr = slabs.ToArray();
}
if (TryAllocateBlockInSlabs(size, slabArr, out allocatedBlock))
{
//found it -- leave
return new ManagedBuffer(allocatedBlock);
}
//Unable to find available free space, so create new slab
MemorySlab newSlab = new MemorySlab(slabSize, this);
newSlab.TryAllocate(size, out allocatedBlock);
lock (sync_slabList)
{
//Add new Slab to collection
slabs.Add(newSlab);
//Add extra slabs as requested in object properties
for (int i = 0; i < subsequentSlabs - 1; i++)
{
slabs.Add(new MemorySlab(slabSize, this));
}
}
}
return new ManagedBuffer(allocatedBlock);
}
/// <summary>
/// Creates a buffer of the specified size
/// </summary>
/// <param name="size">Buffer size, in bytes</param>
/// <returns>IBuffer object of requested size</returns>
public IBuffer GetBuffer(long size)
{
if (size < 0)
{
throw new ArgumentException("Length must be greater than 0");
}
if (size == 0)
{
return(new ManagedBuffer(firstSlab)); //Return an empty buffer
}
IMemoryBlock allocatedBlock;
IMemorySlab[] slabArr;
if (singleSlabPool == -1)
{
//Optimization: Chances are that there'll be just one slab in a pool, so access it directly
//and avoid the lock statement involved while creating an array of slabs.
//Note that even if singleSlabPool is inaccurate, this method will still work properly.
//The optimization is effective because singleSlabPool will be accurate majority of the time.
slabArr = new IMemorySlab[] { firstSlab };
if (TryAllocateBlockInSlabs(size, slabArr, out allocatedBlock))
{
return(new ManagedBuffer(allocatedBlock));
}
Interlocked.Exchange(ref singleSlabPool, 0); // Slab count will soon be incremented
}
else
{
lock (sync_slabList)
{
slabArr = slabs.ToArray();
}
if (TryAllocateBlockInSlabs(size, slabArr, out allocatedBlock))
{
return(new ManagedBuffer(allocatedBlock));
}
}
lock (sync_newSlab)
{
//Look again for free block
lock (sync_slabList)
{
slabArr = slabs.ToArray();
}
if (TryAllocateBlockInSlabs(size, slabArr, out allocatedBlock))
{
//found it -- leave
return(new ManagedBuffer(allocatedBlock));
}
//Unable to find available free space, so create new slab
MemorySlab newSlab = new MemorySlab(slabSize, this);
newSlab.TryAllocate(size, out allocatedBlock);
lock (sync_slabList)
{
//Add new Slab to collection
slabs.Add(newSlab);
//Add extra slabs as requested in object properties
for (int i = 0; i < subsequentSlabs - 1; i++)
{
slabs.Add(new MemorySlab(slabSize, this));
}
}
}
return(new ManagedBuffer(allocatedBlock));
}
/// <summary>
/// Creates a buffer of the specified size, filled with the contents of a specified byte array
/// </summary>
/// <param name="size">Buffer size, in bytes</param>
/// <param name="filledWith">Byte array to copy to buffer</param>
/// <returns>IBuffer object of requested size</returns>
public IBuffer GetBuffer(long size, byte[] filledWith)
{
if (size < 0)
{
throw new ArgumentException("size must be greater than 0");
}
//TODO: If size is larger than 16 * SlabSize (or MaxNumberOfSegments * SlabSize) then throw exception saying you can't have a buffer greater than 16 times Slab size
//Write test for this
//Make sure filledWith can fit into the requested buffer, so that we do not allocate a buffer and then
//an exception is thrown (when IBuffer.FillWith() is called) before the buffer is returned.
if (filledWith != null)
{
if (filledWith.LongLength > size)
{
throw new ArgumentException("Length of filledWith array cannot be larger than desired buffer size");
}
if (filledWith.LongLength == 0)
{
filledWith = null;
}
//TODO: Write test that will test that IBuffer.FillWith() doesn't throw an exception (and that buffers aren't allocated) in this method
}
if (size == 0)
{
//Return an empty buffer
return(new ManagedBuffer(firstSlab));
}
List <IMemoryBlock> allocatedBlocks = new List <IMemoryBlock>();
//TODO: Consider the performance penalty involved in making the try-catch below a constrained region
//RuntimeHelpers.PrepareConstrainedRegions();
try
{
IMemorySlab[] slabArr;
long allocdLengthTally = 0;
if (GetSingleSlabPool())
{
//Optimization: Chances are that there'll be just one slab in a pool, so access it directly
//and avoid the lock statement involved while creating an array of slabs.
//Note that even if singleSlabPool is inaccurate, this method will still work properly.
//The optimization is effective because singleSlabPool will be accurate majority of the time.
slabArr = new IMemorySlab[] { firstSlab };
allocdLengthTally = TryAllocateBlocksInSlabs(size, MAX_SEGMENTS_PER_BUFFER, slabArr, ref allocatedBlocks);
if (allocdLengthTally == size)
{
//We got the entire length we are looking for, so leave
return(GetFilledBuffer(allocatedBlocks, filledWith));
}
SetSingleSlabPool(false); // Slab count will soon be incremented
}
else
{
lock (syncSlabList)
{
slabArr = slabs.ToArray();
}
allocdLengthTally = TryAllocateBlocksInSlabs(size, MAX_SEGMENTS_PER_BUFFER, slabArr, ref allocatedBlocks);
if (allocdLengthTally == size)
{
//We got the entire length we are looking for, so leave
return(GetFilledBuffer(allocatedBlocks, filledWith));
}
}
//Try to create new slab
lock (syncNewSlab)
{
//Look again for free block
lock (syncSlabList)
{
slabArr = slabs.ToArray();
}
allocdLengthTally += TryAllocateBlocksInSlabs(size - allocdLengthTally, MAX_SEGMENTS_PER_BUFFER - allocatedBlocks.Count, slabArr, ref allocatedBlocks);
if (allocdLengthTally == size)
{
//found it -- leave
return(GetFilledBuffer(allocatedBlocks, filledWith));
}
List <IMemorySlab> newSlabList = new List <IMemorySlab>();
do
{
//Unable to find available free space, so create new slab
MemorySlab newSlab = new MemorySlab(slabSize, this);
IMemoryBlock allocdBlk;
if (slabSize > size - allocdLengthTally)
{
//Allocate remnant
newSlab.TryAllocate(size - allocdLengthTally, out allocdBlk);
}
else
{
//Allocate entire slab
newSlab.TryAllocate(slabSize, out allocdBlk);
}
newSlabList.Add(newSlab);
allocatedBlocks.Add(allocdBlk);
allocdLengthTally += allocdBlk.Length;
}while (allocdLengthTally < size);
lock (syncSlabList)
{
//Add new slabs to collection
slabs.AddRange(newSlabList);
//Add extra slabs as requested in object properties
for (int i = 0; i < subsequentSlabs - 1; i++)
{
slabs.Add(new MemorySlab(slabSize, this));
}
}
}
return(GetFilledBuffer(allocatedBlocks, filledWith));
}
catch
{
//OOM, Thread abort exceptions and other ugly things can happen so roll back any allocated blocks.
//This will prevent a limbo situation where those blocks are allocated but caller is unaware and can't deallocate them.
//NOTE: This try-catch block should not be within a lock as it calls MemorySlab.Free which takes locks,
//and in turn calls BufferPool.TryFreeSlabs which takes other locks and can lead to a dead-lock/race condition.
//TODO: Write rollback test.
for (int b = 0; b < allocatedBlocks.Count; b++)
{
allocatedBlocks[b].Slab.Free(allocatedBlocks[b]);
}
throw;
}
}
