Added LightningTransaction.GetEntriesCount

Author: ilyalukyanov

src/LightningDB.Tests/TransactionTests.cs

@@ -169,5 +169,23 @@ public void DefaultDatabaseShouldBeDropped()
             //assert
             Assert.AreEqual(false, db.IsOpened);
         }
+
+        [Test]
+        public void CanCountEntries()
+        {
+            //arrange
+            _txn = _env.BeginTransaction();
+            var db = _txn.OpenDatabase(null, DatabaseOpenFlags.None);
+
+            const int entriesCount = 10;
+            for (var i = 0; i < entriesCount; i++)
+                _txn.Put(db, i.ToString(), i.ToString());
+
+            //act
+            var count = _txn.GetEntriesCount(db);
+
+            //assert;
+            Assert.AreEqual(entriesCount, count);
+        }
     }
 }

src/LightningDB/LightningDB.csproj

@@ -109,6 +109,7 @@
     <Compile Include="LightningTransaction.cs" />
     <Compile Include="LightningVersionInfo.cs" />
     <Compile Include="Native\MarshalValueStructure.cs" />
+    <Compile Include="Native\MDBStat.cs" />
     <Compile Include="Native\Native.cs" />
     <Compile Include="Native\NativeLibraryFacades.cs">
       <AutoGen>True</AutoGen>

src/LightningDB/LightningTransaction.cs

@@ -328,6 +328,14 @@ public void Abort()
             });
         }
 
+        public long GetEntriesCount(LightningDatabase db)
+        {
+            var stat = new MDBStat();
+            NativeMethods.Execute(lib => lib.mdb_stat(_handle, db._handle, out stat));
+
+            return stat.ms_entries.ToInt64();
+        }
+
         /// <summary>
         /// Environment in which the transaction was opened.
         /// </summary>

src/LightningDB/Native/INativeLibraryFacade.cs

@@ -284,6 +284,18 @@ interface INativeLibraryFacade
         /// <returns>The description of the error</returns>
         IntPtr mdb_strerror(int err); //OK
 
+        /// <summary>
+        /// Retrieve statistics for a database.
+        /// </summary>
+        /// <param name="txn">A transaction handle returned by mdb_txn_begin()</param>
+        /// <param name="dbi">A database handle returned by mdb_dbi_open()</param>
+        /// <param name="stat">The address of an MDB_stat structure where the statistics will be copied</param>
+        /// <returns>
+        /// A non-zero error value on failure and 0 on success. Some possible errors are:
+        /// EINVAL - an invalid parameter was specified.
+        /// </returns>
+        int mdb_stat(IntPtr txn, uint dbi, out MDBStat stat);
+
         /// <summary>
         /// Copy an MDB environment to the specified path.
         /// This function may be used to make a backup of an existing environment.

src/LightningDB/Native/MDBStat.cs

@@ -0,0 +1,19 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Runtime.InteropServices;
+using System.Text;
+
+namespace LightningDB.Native
+{
+    [StructLayout(LayoutKind.Sequential)]
+    struct MDBStat
+    {
+        public uint ms_psize;
+        public uint ms_depth;
+        public IntPtr ms_branch_pages;
+        public IntPtr ms_leaf_pages;
+        public IntPtr ms_overflow_pages;
+        public IntPtr ms_entries;
+    }
+}

src/LightningDB/Native/NativeLibraryFacades.cs

@@ -67,6 +67,9 @@ class Native32BitLibraryFacade : INativeLibraryFacade
         [DllImport(LibraryName, CallingConvention = CallingConvention.Cdecl)]
         private static extern IntPtr mdb_strerror(int err);
 
+        [DllImport(LibraryName, CallingConvention = CallingConvention.Cdecl)]
+        private static extern int mdb_stat(IntPtr txn, uint dbi, out MDBStat stat);
+
         [DllImport(LibraryName, CallingConvention = CallingConvention.Cdecl)]
         private static extern int mdb_env_copy(IntPtr env, string path);
 
@@ -207,6 +210,11 @@ IntPtr INativeLibraryFacade.mdb_strerror(int err)
             return Native32BitLibraryFacade.mdb_strerror(err);
         }
 
+        int INativeLibraryFacade.mdb_stat(IntPtr txn, uint dbi, out MDBStat stat)
+        {
+        return Native32BitLibraryFacade.mdb_stat(txn, dbi, out stat);
+        }
+
         int INativeLibraryFacade.mdb_env_copy(IntPtr env, string path)
         {
             return Native32BitLibraryFacade.mdb_env_copy(env, path);
@@ -328,6 +336,9 @@ class Native64BitLibraryFacade : INativeLibraryFacade
         [DllImport(LibraryName, CallingConvention = CallingConvention.Cdecl)]
         private static extern IntPtr mdb_strerror(int err);
 
+        [DllImport(LibraryName, CallingConvention = CallingConvention.Cdecl)]
+        private static extern int mdb_stat(IntPtr txn, uint dbi, out MDBStat stat);
+
         [DllImport(LibraryName, CallingConvention = CallingConvention.Cdecl)]
         private static extern int mdb_env_copy(IntPtr env, string path);
 
@@ -456,6 +467,11 @@ IntPtr INativeLibraryFacade.mdb_strerror(int err)
             return Native64BitLibraryFacade.mdb_strerror(err);
         }
 
+        int INativeLibraryFacade.mdb_stat(IntPtr txn, uint dbi, out MDBStat stat)
+        {
+        return Native64BitLibraryFacade.mdb_stat(txn, dbi, out stat);
+        }
+
         int INativeLibraryFacade.mdb_env_copy(IntPtr env, string path)
         {
             return Native64BitLibraryFacade.mdb_env_copy(env, path);
@@ -577,6 +593,9 @@ class FallbackLibraryFacade : INativeLibraryFacade
         [DllImport(LibraryName, CallingConvention = CallingConvention.Cdecl)]
         private static extern IntPtr mdb_strerror(int err);
 
+        [DllImport(LibraryName, CallingConvention = CallingConvention.Cdecl)]
+        private static extern int mdb_stat(IntPtr txn, uint dbi, out MDBStat stat);
+
         [DllImport(LibraryName, CallingConvention = CallingConvention.Cdecl)]
         private static extern int mdb_env_copy(IntPtr env, string path);
 
@@ -717,6 +736,11 @@ IntPtr INativeLibraryFacade.mdb_strerror(int err)
             return FallbackLibraryFacade.mdb_strerror(err);
         }
 
+        int INativeLibraryFacade.mdb_stat(IntPtr txn, uint dbi, out MDBStat stat)
+        {
+        return FallbackLibraryFacade.mdb_stat(txn, dbi, out stat);
+        }
+
         int INativeLibraryFacade.mdb_env_copy(IntPtr env, string path)
         {
             return FallbackLibraryFacade.mdb_env_copy(env, path);

src/LightningDB/Native/NativeLibraryFacades.tt

@@ -82,6 +82,9 @@ namespace LightningDB.Native
         [DllImport(LibraryName, CallingConvention = CallingConvention.Cdecl)]
         private static extern IntPtr mdb_strerror(int err);
 
+        [DllImport(LibraryName, CallingConvention = CallingConvention.Cdecl)]
+        private static extern int mdb_stat(IntPtr txn, uint dbi, out MDBStat stat);
+
         [DllImport(LibraryName, CallingConvention = CallingConvention.Cdecl)]
         private static extern int mdb_env_copy(IntPtr env, string path);
 
@@ -226,6 +229,11 @@ namespace LightningDB.Native
             return <#= pair.Value #>LibraryFacade.mdb_strerror(err);
         }
 
+        int INativeLibraryFacade.mdb_stat(IntPtr txn, uint dbi, out MDBStat stat)
+        {
+        return <#= pair.Value #>LibraryFacade.mdb_stat(txn, dbi, out stat);
+        }
+
         int INativeLibraryFacade.mdb_env_copy(IntPtr env, string path)
         {
             return <#= pair.Value #>LibraryFacade.mdb_env_copy(env, path);