Mark for 0.19.2

* Use arraypool for transfer/skip

* Merge fixes

* Remove redundant constant

build.cake

@@ -54,13 +54,13 @@ Task("Test")
         DotNetCoreTest(file.ToString(), settings);
 
 
-            settings = new DotNetCoreTestSettings
-            {
-                Configuration = "Release",
-                Framework = "netcoreapp2.0"
-            };
+        settings = new DotNetCoreTestSettings
+        {
+            Configuration = "Release",
+            Framework = "netcoreapp1.1"
+        };
 
-            DotNetCoreTest(file.ToString(), settings);
+        DotNetCoreTest(file.ToString(), settings);
     }
 });
 

src/SharpCompress/Buffers/ArrayPool.cs

@@ -0,0 +1,119 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+#if NETCORE
+using System.Runtime.CompilerServices;
+using System.Threading;
+
+namespace SharpCompress.Buffers
+{
+    /// <summary>
+    /// Provides a resource pool that enables reusing instances of type <see cref="T:T[]"/>. 
+    /// </summary>
+    /// <remarks>
+    /// <para>
+    /// Renting and returning buffers with an <see cref="ArrayPool{T}"/> can increase performance
+    /// in situations where arrays are created and destroyed frequently, resulting in significant
+    /// memory pressure on the garbage collector.
+    /// </para>
+    /// <para>
+    /// This class is thread-safe.  All members may be used by multiple threads concurrently.
+    /// </para>
+    /// </remarks>
+    internal abstract class ArrayPool<T>
+    {
+        /// <summary>The lazily-initialized shared pool instance.</summary>
+        private static ArrayPool<T> s_sharedInstance = null;
+
+        /// <summary>
+        /// Retrieves a shared <see cref="ArrayPool{T}"/> instance.
+        /// </summary>
+        /// <remarks>
+        /// The shared pool provides a default implementation of <see cref="ArrayPool{T}"/>
+        /// that's intended for general applicability.  It maintains arrays of multiple sizes, and 
+        /// may hand back a larger array than was actually requested, but will never hand back a smaller 
+        /// array than was requested. Renting a buffer from it with <see cref="Rent"/> will result in an 
+        /// existing buffer being taken from the pool if an appropriate buffer is available or in a new 
+        /// buffer being allocated if one is not available.
+        /// </remarks>
+        public static ArrayPool<T> Shared
+        {
+            [MethodImpl(MethodImplOptions.AggressiveInlining)]
+            get { return Volatile.Read(ref s_sharedInstance) ?? EnsureSharedCreated(); }
+        }
+
+        /// <summary>Ensures that <see cref="s_sharedInstance"/> has been initialized to a pool and returns it.</summary>
+        [MethodImpl(MethodImplOptions.NoInlining)]
+        private static ArrayPool<T> EnsureSharedCreated()
+        {
+            Interlocked.CompareExchange(ref s_sharedInstance, Create(), null);
+            return s_sharedInstance;
+        }
+
+        /// <summary>
+        /// Creates a new <see cref="ArrayPool{T}"/> instance using default configuration options.
+        /// </summary>
+        /// <returns>A new <see cref="ArrayPool{T}"/> instance.</returns>
+        public static ArrayPool<T> Create()
+        {
+            return new DefaultArrayPool<T>();
+        }
+
+        /// <summary>
+        /// Creates a new <see cref="ArrayPool{T}"/> instance using custom configuration options.
+        /// </summary>
+        /// <param name="maxArrayLength">The maximum length of array instances that may be stored in the pool.</param>
+        /// <param name="maxArraysPerBucket">
+        /// The maximum number of array instances that may be stored in each bucket in the pool.  The pool
+        /// groups arrays of similar lengths into buckets for faster access.
+        /// </param>
+        /// <returns>A new <see cref="ArrayPool{T}"/> instance with the specified configuration options.</returns>
+        /// <remarks>
+        /// The created pool will group arrays into buckets, with no more than <paramref name="maxArraysPerBucket"/>
+        /// in each bucket and with those arrays not exceeding <paramref name="maxArrayLength"/> in length.
+        /// </remarks>
+        public static ArrayPool<T> Create(int maxArrayLength, int maxArraysPerBucket)
+        {
+            return new DefaultArrayPool<T>(maxArrayLength, maxArraysPerBucket);
+        }
+
+        /// <summary>
+        /// Retrieves a buffer that is at least the requested length.
+        /// </summary>
+        /// <param name="minimumLength">The minimum length of the array needed.</param>
+        /// <returns>
+        /// An <see cref="T:T[]"/> that is at least <paramref name="minimumLength"/> in length.
+        /// </returns>
+        /// <remarks>
+        /// This buffer is loaned to the caller and should be returned to the same pool via 
+        /// <see cref="Return"/> so that it may be reused in subsequent usage of <see cref="Rent"/>.  
+        /// It is not a fatal error to not return a rented buffer, but failure to do so may lead to 
+        /// decreased application performance, as the pool may need to create a new buffer to replace
+        /// the one lost.
+        /// </remarks>
+        public abstract T[] Rent(int minimumLength);
+
+        /// <summary>
+        /// Returns to the pool an array that was previously obtained via <see cref="Rent"/> on the same 
+        /// <see cref="ArrayPool{T}"/> instance.
+        /// </summary>
+        /// <param name="array">
+        /// The buffer previously obtained from <see cref="Rent"/> to return to the pool.
+        /// </param>
+        /// <param name="clearArray">
+        /// If <c>true</c> and if the pool will store the buffer to enable subsequent reuse, <see cref="Return"/>
+        /// will clear <paramref name="array"/> of its contents so that a subsequent consumer via <see cref="Rent"/> 
+        /// will not see the previous consumer's content.  If <c>false</c> or if the pool will release the buffer,
+        /// the array's contents are left unchanged.
+        /// </param>
+        /// <remarks>
+        /// Once a buffer has been returned to the pool, the caller gives up all ownership of the buffer 
+        /// and must not use it. The reference returned from a given call to <see cref="Rent"/> must only be
+        /// returned via <see cref="Return"/> once.  The default <see cref="ArrayPool{T}"/>
+        /// may hold onto the returned buffer in order to rent it again, or it may release the returned buffer
+        /// if it's determined that the pool already has enough buffers stored.
+        /// </remarks>
+        public abstract void Return(T[] array, bool clearArray = false);
+    }
+}
+#endif

src/SharpCompress/Buffers/DefaultArrayPool.cs

@@ -0,0 +1,144 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+#if NETCORE
+using System;
+
+namespace SharpCompress.Buffers
+{
+    internal sealed partial class DefaultArrayPool<T> : ArrayPool<T>
+    {
+        /// <summary>The default maximum length of each array in the pool (2^20).</summary>
+        private const int DefaultMaxArrayLength = 1024 * 1024;
+        /// <summary>The default maximum number of arrays per bucket that are available for rent.</summary>
+        private const int DefaultMaxNumberOfArraysPerBucket = 50;
+        /// <summary>Lazily-allocated empty array used when arrays of length 0 are requested.</summary>
+        private static T[] s_emptyArray; // we support contracts earlier than those with Array.Empty<T>()
+
+        private readonly Bucket[] _buckets;
+
+        internal DefaultArrayPool() : this(DefaultMaxArrayLength, DefaultMaxNumberOfArraysPerBucket)
+        {
+        }
+
+        internal DefaultArrayPool(int maxArrayLength, int maxArraysPerBucket)
+        {
+            if (maxArrayLength <= 0)
+            {
+                throw new ArgumentOutOfRangeException(nameof(maxArrayLength));
+            }
+            if (maxArraysPerBucket <= 0)
+            {
+                throw new ArgumentOutOfRangeException(nameof(maxArraysPerBucket));
+            }
+
+            // Our bucketing algorithm has a min length of 2^4 and a max length of 2^30.
+            // Constrain the actual max used to those values.
+            const int MinimumArrayLength = 0x10, MaximumArrayLength = 0x40000000;
+            if (maxArrayLength > MaximumArrayLength)
+            {
+                maxArrayLength = MaximumArrayLength;
+            }
+            else if (maxArrayLength < MinimumArrayLength)
+            {
+                maxArrayLength = MinimumArrayLength;
+            }
+
+            // Create the buckets.
+            int poolId = Id;
+            int maxBuckets = Utilities.SelectBucketIndex(maxArrayLength);
+            var buckets = new Bucket[maxBuckets + 1];
+            for (int i = 0; i < buckets.Length; i++)
+            {
+                buckets[i] = new Bucket(Utilities.GetMaxSizeForBucket(i), maxArraysPerBucket, poolId);
+            }
+            _buckets = buckets;
+        }
+
+        /// <summary>Gets an ID for the pool to use with events.</summary>
+        private int Id => GetHashCode();
+
+        public override T[] Rent(int minimumLength)
+        {
+            // Arrays can't be smaller than zero.  We allow requesting zero-length arrays (even though
+            // pooling such an array isn't valuable) as it's a valid length array, and we want the pool
+            // to be usable in general instead of using `new`, even for computed lengths.
+            if (minimumLength < 0)
+            {
+                throw new ArgumentOutOfRangeException(nameof(minimumLength));
+            }
+            else if (minimumLength == 0)
+            {
+                // No need for events with the empty array.  Our pool is effectively infinite
+                // and we'll never allocate for rents and never store for returns.
+                return s_emptyArray ?? (s_emptyArray = new T[0]);
+            }
+
+            T[] buffer = null;
+
+            int index = Utilities.SelectBucketIndex(minimumLength);
+            if (index < _buckets.Length)
+            {
+                // Search for an array starting at the 'index' bucket. If the bucket is empty, bump up to the
+                // next higher bucket and try that one, but only try at most a few buckets.
+                const int MaxBucketsToTry = 2;
+                int i = index;
+                do
+                {
+                    // Attempt to rent from the bucket.  If we get a buffer from it, return it.
+                    buffer = _buckets[i].Rent();
+                    if (buffer != null)
+                    {
+                        return buffer;
+                    }
+                }
+                while (++i < _buckets.Length && i != index + MaxBucketsToTry);
+
+                // The pool was exhausted for this buffer size.  Allocate a new buffer with a size corresponding
+                // to the appropriate bucket.
+                buffer = new T[_buckets[index]._bufferLength];
+            }
+            else
+            {
+                // The request was for a size too large for the pool.  Allocate an array of exactly the requested length.
+                // When it's returned to the pool, we'll simply throw it away.
+                buffer = new T[minimumLength];
+            }
+
+            return buffer;
+        }
+
+        public override void Return(T[] array, bool clearArray = false)
+        {
+            if (array == null)
+            {
+                throw new ArgumentNullException(nameof(array));
+            }
+            else if (array.Length == 0)
+            {
+                // Ignore empty arrays.  When a zero-length array is rented, we return a singleton
+                // rather than actually taking a buffer out of the lowest bucket.
+                return;
+            }
+
+            // Determine with what bucket this array length is associated
+            int bucket = Utilities.SelectBucketIndex(array.Length);
+
+            // If we can tell that the buffer was allocated, drop it. Otherwise, check if we have space in the pool
+            if (bucket < _buckets.Length)
+            {
+                // Clear the array if the user requests
+                if (clearArray)
+                {
+                    Array.Clear(array, 0, array.Length);
+                }
+
+                // Return the buffer to its bucket.  In the future, we might consider having Return return false
+                // instead of dropping a bucket, in which case we could try to return to a lower-sized bucket,
+                // just as how in Rent we allow renting from a higher-sized bucket.
+                _buckets[bucket].Return(array);
+            }
+        }
+    }
+}
+#endif

src/SharpCompress/Buffers/DefaultArrayPoolBucket.cs

@@ -0,0 +1,111 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+#if NETCORE
+using System;
+using System.Diagnostics;
+using System.Threading;
+
+namespace SharpCompress.Buffers
+{
+    internal sealed partial class DefaultArrayPool<T> : ArrayPool<T>
+    {
+        /// <summary>Provides a thread-safe bucket containing buffers that can be Rent'd and Return'd.</summary>
+        private sealed class Bucket
+        {
+            internal readonly int _bufferLength;
+            private readonly T[][] _buffers;
+            private readonly int _poolId;
+
+            private SpinLock _lock; // do not make this readonly; it's a mutable struct
+            private int _index;
+
+            /// <summary>
+            /// Creates the pool with numberOfBuffers arrays where each buffer is of bufferLength length.
+            /// </summary>
+            internal Bucket(int bufferLength, int numberOfBuffers, int poolId)
+            {
+                _lock = new SpinLock(Debugger.IsAttached); // only enable thread tracking if debugger is attached; it adds non-trivial overheads to Enter/Exit
+                _buffers = new T[numberOfBuffers][];
+                _bufferLength = bufferLength;
+                _poolId = poolId;
+            }
+
+            /// <summary>Gets an ID for the bucket to use with events.</summary>
+            internal int Id => GetHashCode();
+
+            /// <summary>Takes an array from the bucket.  If the bucket is empty, returns null.</summary>
+            internal T[] Rent()
+            {
+                T[][] buffers = _buffers;
+                T[] buffer = null;
+
+                // While holding the lock, grab whatever is at the next available index and
+                // update the index.  We do as little work as possible while holding the spin
+                // lock to minimize contention with other threads.  The try/finally is
+                // necessary to properly handle thread aborts on platforms which have them.
+                bool lockTaken = false, allocateBuffer = false;
+                try
+                {
+                    _lock.Enter(ref lockTaken);
+
+                    if (_index < buffers.Length)
+                    {
+                        buffer = buffers[_index];
+                        buffers[_index++] = null;
+                        allocateBuffer = buffer == null;
+                    }
+                }
+                finally
+                {
+                    if (lockTaken) _lock.Exit(false);
+                }
+
+                // While we were holding the lock, we grabbed whatever was at the next available index, if
+                // there was one.  If we tried and if we got back null, that means we hadn't yet allocated
+                // for that slot, in which case we should do so now.
+                if (allocateBuffer)
+                {
+                    buffer = new T[_bufferLength];
+                }
+
+                return buffer;
+            }
+
+            /// <summary>
+            /// Attempts to return the buffer to the bucket.  If successful, the buffer will be stored
+            /// in the bucket and true will be returned; otherwise, the buffer won't be stored, and false
+            /// will be returned.
+            /// </summary>
+            internal void Return(T[] array)
+            {
+                // Check to see if the buffer is the correct size for this bucket
+                if (array.Length != _bufferLength)
+                {
+                    throw new ArgumentException("Buffer not from pool", nameof(array));
+                }
+
+                // While holding the spin lock, if there's room available in the bucket,
+                // put the buffer into the next available slot.  Otherwise, we just drop it.
+                // The try/finally is necessary to properly handle thread aborts on platforms
+                // which have them.
+                bool lockTaken = false;
+                try
+                {
+                    _lock.Enter(ref lockTaken);
+
+                    if (_index != 0)
+                    {
+                        _buffers[--_index] = array;
+                    }
+                }
+                finally
+                {
+                    if (lockTaken) _lock.Exit(false);
+                }
+            }
+        }
+    }
+}
+#endif

src/SharpCompress/Buffers/Utilities.cs

@@ -0,0 +1,38 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+#if NETCORE
+using System.Diagnostics;
+using System.Runtime.CompilerServices;
+
+namespace SharpCompress.Buffers
+{
+    internal static class Utilities
+    {
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        internal static int SelectBucketIndex(int bufferSize)
+        {
+            Debug.Assert(bufferSize > 0);
+
+            uint bitsRemaining = ((uint)bufferSize - 1) >> 4;
+
+            int poolIndex = 0;
+            if (bitsRemaining > 0xFFFF) { bitsRemaining >>= 16; poolIndex = 16; }
+            if (bitsRemaining > 0xFF)   { bitsRemaining >>= 8;  poolIndex += 8; }
+            if (bitsRemaining > 0xF)    { bitsRemaining >>= 4;  poolIndex += 4; }
+            if (bitsRemaining > 0x3)    { bitsRemaining >>= 2;  poolIndex += 2; }
+            if (bitsRemaining > 0x1)    { bitsRemaining >>= 1;  poolIndex += 1; }
+
+            return poolIndex + (int)bitsRemaining;
+        }
+
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        internal static int GetMaxSizeForBucket(int binIndex)
+        {
+            int maxSize = 16 << binIndex;
+            Debug.Assert(maxSize >= 0);
+            return maxSize;
+        }
+    }
+}
+#endif

src/SharpCompress/SharpCompress.csproj

@@ -2,9 +2,9 @@
   <PropertyGroup>
     <AssemblyTitle>SharpCompress - Pure C# Decompression/Compression</AssemblyTitle>
     <NeutralLanguage>en-US</NeutralLanguage>
-    <VersionPrefix>0.18.2</VersionPrefix>
-    <AssemblyVersion>0.18.2.0</AssemblyVersion>
-    <FileVersion>0.18.2.0</FileVersion>
+    <VersionPrefix>0.19.2</VersionPrefix>
+    <AssemblyVersion>0.19.2.0</AssemblyVersion>
+    <FileVersion>0.19.2.0</FileVersion>
     <Authors>Adam Hathcock</Authors>
     <TargetFrameworks Condition="'$(LibraryFrameworks)'==''">net45;net35;netstandard1.0;netstandard1.3;netstandard2.0</TargetFrameworks>
     <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
@@ -24,4 +24,10 @@
   <PropertyGroup Condition=" '$(TargetFramework)' == 'netstandard1.0' ">
     <DefineConstants>$(DefineConstants);NO_FILE;NO_CRYPTO;SILVERLIGHT</DefineConstants>
   </PropertyGroup>
+  <PropertyGroup Condition=" '$(TargetFramework)' == 'netstandard1.3' ">
+    <DefineConstants>$(DefineConstants);NETCORE</DefineConstants>
+  </PropertyGroup>
+  <PropertyGroup Condition=" '$(TargetFramework)' == 'netstandard2.0' ">
+    <DefineConstants>$(DefineConstants);NETCORE</DefineConstants>
+  </PropertyGroup>
 </Project>

src/SharpCompress/Utility.cs

@@ -2,12 +2,15 @@ using System;
 using System.Collections.Generic;
 using System.IO;
 using System.Linq;
+#if NETCORE
+using SharpCompress.Buffers;
+#endif
 using SharpCompress.Readers;
 
 namespace SharpCompress
 {
     internal static class Utility
-    {   
+    {
         public static ReadOnlyCollection<T> ToReadOnly<T>(this IEnumerable<T> items)
         {
             return new ReadOnlyCollection<T>(items.ToList());
@@ -139,36 +142,54 @@ namespace SharpCompress
         public static void Skip(this Stream source, long advanceAmount)
         {
             byte[] buffer = GetTransferByteArray();
-            int read = 0;
-            int readCount = 0;
-            do
+            try
             {
-                readCount = buffer.Length;
-                if (readCount > advanceAmount)
+                int read = 0;
+                int readCount = 0;
+                do
                 {
-                    readCount = (int)advanceAmount;
-                }
-                read = source.Read(buffer, 0, readCount);
-                if (read <= 0)
-                {
-                    break;
-                }
-                advanceAmount -= read;
-                if (advanceAmount == 0)
-                {
-                    break;
+                    readCount = buffer.Length;
+                    if (readCount > advanceAmount)
+                    {
+                        readCount = (int)advanceAmount;
+                    }
+                    read = source.Read(buffer, 0, readCount);
+                    if (read <= 0)
+                    {
+                        break;
+                    }
+                    advanceAmount -= read;
+                    if (advanceAmount == 0)
+                    {
+                        break;
+                    }
                 }
+                while (true);
+            }
+            finally
+            {
+#if NETCORE
+                ArrayPool<byte>.Shared.Return(buffer);
+#endif
             }
-            while (true);
         }
 
         public static void Skip(this Stream source)
         {
             byte[] buffer = GetTransferByteArray();
-            do
+            try
             {
+                do
+                {
+                }
+                while (source.Read(buffer, 0, buffer.Length) == buffer.Length);
+            }
+            finally
+            {
+#if NETCORE
+                ArrayPool<byte>.Shared.Return(buffer);
+#endif
             }
-            while (source.Read(buffer, 0, buffer.Length) == buffer.Length);
         }
 
         public static DateTime DosDateToDateTime(UInt16 iDate, UInt16 iTime)
@@ -233,30 +254,48 @@ namespace SharpCompress
         public static long TransferTo(this Stream source, Stream destination)
         {
             byte[] array = GetTransferByteArray();
-            int count;
-            long total = 0;
-            while (ReadTransferBlock(source, array, out count))
+            try
             {
-                total += count;
-                destination.Write(array, 0, count);
+                int count;
+                long total = 0;
+                while (ReadTransferBlock(source, array, out count))
+                {
+                    total += count;
+                    destination.Write(array, 0, count);
+                }
+                return total;
+            }
+            finally
+            {
+#if NETCORE
+                ArrayPool<byte>.Shared.Return(array);
+#endif
             }
-            return total;
         }
 
         public static long TransferTo(this Stream source, Stream destination, Common.Entry entry, IReaderExtractionListener readerExtractionListener)
         {
             byte[] array = GetTransferByteArray();
-            int count;
-            var iterations = 0;
-            long total = 0;
-            while (ReadTransferBlock(source, array, out count))
+            try
             {
-                total += count;
-                destination.Write(array, 0, count);
-                iterations++;
-                readerExtractionListener.FireEntryExtractionProgress(entry, total, iterations);
+                int count;
+                var iterations = 0;
+                long total = 0;
+                while (ReadTransferBlock(source, array, out count))
+                {
+                    total += count;
+                    destination.Write(array, 0, count);
+                    iterations++;
+                    readerExtractionListener.FireEntryExtractionProgress(entry, total, iterations);
+                }
+                return total;
+            }
+            finally
+            {
+#if NETCORE
+                ArrayPool<byte>.Shared.Return(array);
+#endif
             }
-            return total;
         }
 
         private static bool ReadTransferBlock(Stream source, byte[] array, out int count)
@@ -266,7 +305,11 @@ namespace SharpCompress
 
         private static byte[] GetTransferByteArray()
         {
+#if NETCORE
+            return ArrayPool<byte>.Shared.Rent(81920);
+#else
             return new byte[81920];
+#endif
         }
 
         public static bool ReadFully(this Stream stream, byte[] buffer)

tests/SharpCompress.Test/SharpCompress.Test.csproj

@@ -1,6 +1,6 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
-    <TargetFrameworks>netcoreapp2.0</TargetFrameworks>
+    <TargetFrameworks>netcoreapp1.1;netcoreapp2.0</TargetFrameworks>
     <AssemblyName>SharpCompress.Test</AssemblyName>
     <AssemblyOriginatorKeyFile>../../SharpCompress.snk</AssemblyOriginatorKeyFile>
     <SignAssembly>true</SignAssembly>