Add span overloads to API

src/LightningDB.Tests/CursorTests.cs

@@ -70,8 +70,8 @@ public void CursorShouldMoveToLast()
             {
                 Assert.True(cur.MoveToLast());
 
-                var lastKey = UTF8.GetString(cur.Current.Key.Span.ToArray());
-                var lastValue = UTF8.GetString(cur.Current.Value.Span.ToArray());
+                var lastKey = UTF8.GetString(cur.Current.Key.CopyToNewArray());
+                var lastValue = UTF8.GetString(cur.Current.Value.CopyToNewArray());
 
                 Assert.Equal("key5", lastKey);
                 Assert.Equal("key5", lastValue);
@@ -88,8 +88,8 @@ public void CursorShouldMoveToFirst()
             {
                 cur.MoveToFirst();
 
-                var lastKey = UTF8.GetString(cur.Current.Key.Span.ToArray());
-                var lastValue = UTF8.GetString(cur.Current.Value.Span.ToArray());
+                var lastKey = UTF8.GetString(cur.Current.Key.CopyToNewArray());
+                var lastValue = UTF8.GetString(cur.Current.Value.CopyToNewArray());
 
                 Assert.Equal("key1", lastKey);
                 Assert.Equal("key1", lastValue);
@@ -108,8 +108,8 @@ public void ShouldIterateThroughCursor()
 
                 while (cur.MoveNext())
                 {
-                    var key = UTF8.GetString(cur.Current.Key.Span.ToArray());
-                    var value = UTF8.GetString(cur.Current.Value.Span.ToArray());
+                    var key = UTF8.GetString(cur.Current.Key.CopyToNewArray());
+                    var value = UTF8.GetString(cur.Current.Value.CopyToNewArray());
 
                     var name = "key" + ++i;
 
@@ -136,7 +136,7 @@ public void CursorShouldDeleteElements()
             }
             using(var cursor = _txn.CreateCursor(_db))
             {
-                var foundDeleted = cursor.Select(x => UTF8.GetString(x.Key.Span.ToArray()))
+                var foundDeleted = cursor.Select(x => UTF8.GetString(x.Key.CopyToNewArray()))
                     .Any(x => x == "key1" || x == "key2");
                 Assert.False(foundDeleted);
             }
@@ -154,8 +154,8 @@ public void ShouldIterateThroughCursorByEnumerator()
                 foreach (var pair in cursor)
                 {
                     var name = "key" + ++i;
-                    Assert.Equal(name, UTF8.GetString(pair.Key.Span.ToArray()));
-                    Assert.Equal(name, UTF8.GetString(pair.Value.Span.ToArray()));
+                    Assert.Equal(name, UTF8.GetString(pair.Key.CopyToNewArray()));
+                    Assert.Equal(name, UTF8.GetString(pair.Value.CopyToNewArray()));
                 }
             }
         }
@@ -180,7 +180,7 @@ public void ShouldPutMultiple()
                 }
             }
 
-            Assert.Equal(values, pairs.Select(x => x.Value.Span.ToArray()).ToArray());
+            Assert.Equal(values, pairs.Select(x => x.Value.CopyToNewArray()).ToArray());
         }
 
         [Fact]
@@ -198,8 +198,8 @@ public void ShouldGetMultiple()
                 cur.MoveNext();
                 cur.GetMultiple();
                 var resultPair = cur.Current;
-                Assert.Equal("TestKey", UTF8.GetString(resultPair.Key.Span.ToArray()));
-                var result = resultPair.Value.Span.ToArray().Split(sizeof(int))
+                Assert.Equal("TestKey", UTF8.GetString(resultPair.Key.CopyToNewArray()));
+                var result = resultPair.Value.CopyToNewArray().Split(sizeof(int))
                     .Select(x => BitConverter.ToInt32(x.ToArray(), 0)).ToArray();
                 Assert.Equal(original, result);
             }
@@ -219,8 +219,8 @@ public void ShouldMoveNextMultiple()
             {
                 cur.MoveNextMultiple();
                 var resultPair = cur.Current;
-                Assert.Equal("TestKey", UTF8.GetString(resultPair.Key.Span.ToArray()));
-                var result = resultPair.Value.Span.ToArray().Split(sizeof(int))
+                Assert.Equal("TestKey", UTF8.GetString(resultPair.Key.CopyToNewArray()));
+                var result = resultPair.Value.CopyToNewArray().Split(sizeof(int))
                     .Select(x => BitConverter.ToInt32(x.ToArray(), 0)).ToArray();
                 Assert.Equal(original, result);
             }

src/LightningDB.Tests/DatabaseTests.cs

@@ -89,7 +89,7 @@ public void NamedDatabaseNameExistsInMaster()
                 using (var cursor = tx.CreateCursor(db))
                 {
                     cursor.MoveNext();
-                    Assert.Equal("customdb", UTF8.GetString(cursor.Current.Key.Span.ToArray()));
+                    Assert.Equal("customdb", UTF8.GetString(cursor.Current.Key.CopyToNewArray()));
                 }
             }
         }

src/LightningDB.Tests/TransactionTests.cs

@@ -3,10 +3,57 @@
 using System.Collections.Generic;
 using LightningDB.Native;
 using Xunit;
+using System.Runtime.InteropServices;
 
 namespace LightningDB.Tests
 {
     [Collection("SharedFileSystem")]
+    public class TransactionDupFixedTests : IDisposable
+    {
+        private LightningEnvironment _env;
+
+        public TransactionDupFixedTests(SharedFileSystem fileSystem)
+        {
+            var path = fileSystem.CreateNewDirectoryForTest();
+            _env = new LightningEnvironment(path);
+            _env.Open();
+        }
+
+        public void Dispose()
+        {
+            _env.Dispose();
+        }
+
+
+        [Fact]
+        public void CanCountTransactionEntries()
+        {
+            LightningDatabase db;
+
+            using (var openDbTxn = _env.BeginTransaction())
+            {
+                db = openDbTxn.OpenDatabase();
+            }
+
+            var key = MemoryMarshal.Cast<char, byte>("abcd");
+
+            using(var writeTxn = _env.BeginTransaction())
+            {
+                writeTxn.Put(db, key, MemoryMarshal.Cast<char,byte>("Value1"));
+                writeTxn.Put(db, key, MemoryMarshal.Cast<char, byte>("Value2"));
+                writeTxn.Commit();
+            }
+
+            using (var delTxn = _env.BeginTransaction())
+            {
+                delTxn.Delete(db, key, null);//should not throw
+                delTxn.Commit();
+            }
+        }
+    }
+
+
+        [Collection("SharedFileSystem")]
     public class TransactionTests : IDisposable
     {
         private LightningEnvironment _env;
@@ -145,7 +192,7 @@ public void TransactionShouldSupportCustomComparer()
             Func<int, int, int> comparison = (l, r) => l.CompareTo(r);
             var options = new DatabaseConfiguration {Flags = DatabaseOpenFlags.Create};
             Func<MDBValue, MDBValue, int> compareWith =
-                (l, r) => comparison(BitConverter.ToInt32(l.Span.ToArray(), 0), BitConverter.ToInt32(r.Span.ToArray(), 0));
+                (l, r) => comparison(BitConverter.ToInt32(l.CopyToNewArray(), 0), BitConverter.ToInt32(r.CopyToNewArray(), 0));
             options.CompareWith(Comparer<MDBValue>.Create(new Comparison<MDBValue>(compareWith)));
 
             using (var txnT = _env.BeginTransaction())
@@ -170,7 +217,7 @@ public void TransactionShouldSupportCustomComparer()
             {
                 int order = 0;
                 while (c.MoveNext())
-                    Assert.Equal(keysSorted[order++], BitConverter.ToInt32(c.Current.Key.Span.ToArray(), 0));
+                    Assert.Equal(keysSorted[order++], BitConverter.ToInt32(c.Current.Key.CopyToNewArray(), 0));
             }
         }
 
@@ -181,7 +228,7 @@ public void TransactionShouldSupportCustomDupSorter()
 
             var txn = _env.BeginTransaction();
             var options = new DatabaseConfiguration {Flags = DatabaseOpenFlags.Create | DatabaseOpenFlags.DuplicatesFixed};
-            Func<MDBValue, MDBValue, int> compareWith = (l, r) => comparison(BitConverter.ToInt32(l.Span.ToArray(), 0), BitConverter.ToInt32(r.Span.ToArray(), 0));
+            Func<MDBValue, MDBValue, int> compareWith = (l, r) => comparison(BitConverter.ToInt32(l.CopyToNewArray(), 0), BitConverter.ToInt32(r.CopyToNewArray(), 0));
             options.FindDuplicatesWith(Comparer<MDBValue>.Create(new Comparison<MDBValue>(compareWith)));
             var db = txn.OpenDatabase(configuration: options);
 
@@ -197,7 +244,7 @@ public void TransactionShouldSupportCustomDupSorter()
                 int order = 0;
 
                 while (c.MoveNext())
-                    Assert.Equal(valuesSorted[order++], BitConverter.ToInt32(c.Current.Value.Span.ToArray(), 0));
+                    Assert.Equal(valuesSorted[order++], BitConverter.ToInt32(c.Current.Value.CopyToNewArray(), 0));
             }
         }
     }

src/LightningDB/EnvironmentInfo.cs

@@ -1,9 +1,23 @@
 namespace LightningDB
 {
+    /// <summary>
+    /// Information about the environment. 
+    /// </summary>
     public class EnvironmentInfo
     {
+        /// <summary>
+        /// ID of the last used page 
+        /// </summary>
         public int LastPageNumber { get; set; }
+
+        /// <summary>
+        /// ID of the last committed transaction  
+        /// </summary>
         public int LastTransactionId { get; set; }
+
+        /// <summary>
+        /// Size of the data memory map 
+        /// </summary>
         public int MapSize { get; set; }
     }
 }

src/LightningDB/GetResult.cs

@@ -0,0 +1,70 @@
+namespace LightningDB
+{
+    /// <summary>
+    /// A struct describing the result of a TryGet operation
+    /// </summary>
+    public readonly struct GetResult
+    {
+        public GetResult(GetResultCode resultCode, int valueLength)
+        {
+            ResultCode = resultCode;
+            ValueLength = valueLength;
+        }
+
+        /// <summary>
+        /// A success/error code for the Get operation
+        /// </summary>
+        public GetResultCode ResultCode { get; }
+
+        /// <summary>
+        /// If the key was found, this represents the length of the value
+        /// in the database.
+        /// 
+        /// <para>
+        ///     If the key was not found, this value is 0 and has no meaning.
+        /// </para>
+        /// </summary>
+        public int ValueLength { get; }
+    }
+
+    /// <summary>
+    /// An enumeration describing the result of a TryGet operation
+    /// </summary>
+    public enum GetResultCode
+    {
+        /// <summary>
+        /// Success! The requested key was found and the value was copied to 
+        /// the provided buffer.
+        /// <para>
+        ///     GetResult.Length represents the length of the value found in
+        ///     the database. (This is also the length of data copied into
+        ///     the provided buffer.)
+        /// </para>
+        /// </summary>
+        Success,
+
+        /// <summary>
+        /// Failure. The requested key was found, but the provided buffer was
+        /// too small to contain the full value. No data has been retrived.
+        /// The Get operation should be retried with a buffer at least the 
+        /// length represented in GetResult.Length
+        /// <para>
+        ///     GetResult.Length represents the length of the value found in
+        ///     the database. (This is the minimum buffer length needed for 
+        ///     the operation to succeed)
+        /// </para>
+        /// </summary>
+        DestinationTooSmall,
+
+        /// <summary>
+        /// Failure. The requested key was not found in the database. No data has 
+        /// been retrived.
+        /// <para>
+        ///     GetResult.Length has no meaning for this result. It's value
+        ///     is set to zero.
+        /// </para>
+        /// </summary>
+        KeyNotFound
+    }
+
+}