Support "use/drop database"

Author: Banyc

MiniSQL.sln

@@ -19,6 +19,8 @@ Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "MiniSQL.RecordManager", "sr
 EndProject
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "MiniSQL.Library", "src\MiniSQL.Library\MiniSQL.Library.csproj", "{3EA08587-04EB-40CA-B025-5D02A9030178}"
 EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "MiniSQL.Startup", "src\MiniSQL.Startup\MiniSQL.Startup.csproj", "{B6695733-2C87-4D7B-B8A8-0BC444A23712}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -116,6 +118,18 @@ Global
 		{3EA08587-04EB-40CA-B025-5D02A9030178}.Release|x64.Build.0 = Release|Any CPU
 		{3EA08587-04EB-40CA-B025-5D02A9030178}.Release|x86.ActiveCfg = Release|Any CPU
 		{3EA08587-04EB-40CA-B025-5D02A9030178}.Release|x86.Build.0 = Release|Any CPU
+		{B6695733-2C87-4D7B-B8A8-0BC444A23712}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{B6695733-2C87-4D7B-B8A8-0BC444A23712}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{B6695733-2C87-4D7B-B8A8-0BC444A23712}.Debug|x64.ActiveCfg = Debug|Any CPU
+		{B6695733-2C87-4D7B-B8A8-0BC444A23712}.Debug|x64.Build.0 = Debug|Any CPU
+		{B6695733-2C87-4D7B-B8A8-0BC444A23712}.Debug|x86.ActiveCfg = Debug|Any CPU
+		{B6695733-2C87-4D7B-B8A8-0BC444A23712}.Debug|x86.Build.0 = Debug|Any CPU
+		{B6695733-2C87-4D7B-B8A8-0BC444A23712}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{B6695733-2C87-4D7B-B8A8-0BC444A23712}.Release|Any CPU.Build.0 = Release|Any CPU
+		{B6695733-2C87-4D7B-B8A8-0BC444A23712}.Release|x64.ActiveCfg = Release|Any CPU
+		{B6695733-2C87-4D7B-B8A8-0BC444A23712}.Release|x64.Build.0 = Release|Any CPU
+		{B6695733-2C87-4D7B-B8A8-0BC444A23712}.Release|x86.ActiveCfg = Release|Any CPU
+		{B6695733-2C87-4D7B-B8A8-0BC444A23712}.Release|x86.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(NestedProjects) = preSolution
 		{C40E4A7D-AFD1-45A0-8AA5-EE52EE583FF9} = {73A93E49-D1AE-4052-909C-AD8EED74D8D7}
@@ -125,5 +139,6 @@ Global
 		{05C292B3-4C6B-4470-9EDB-725DEF786183} = {73A93E49-D1AE-4052-909C-AD8EED74D8D7}
 		{511A214E-372C-4D27-8EE7-50CFAD5F8505} = {73A93E49-D1AE-4052-909C-AD8EED74D8D7}
 		{3EA08587-04EB-40CA-B025-5D02A9030178} = {73A93E49-D1AE-4052-909C-AD8EED74D8D7}
+		{B6695733-2C87-4D7B-B8A8-0BC444A23712} = {73A93E49-D1AE-4052-909C-AD8EED74D8D7}
 	EndGlobalSection
 EndGlobal

README.md

@@ -52,6 +52,12 @@ execfile "PATH_TO_SQL_FILE" ;
 
 -- ensure writing back all dirty pages
 exit
+
+-- write all pages back to disk
+flush
+
+use database DATABASE_NAME
+drop database DATABASE_NAME
 ```
 
 ## Spec

src/MiniSQL.Api/Api.cs renamed to src/MiniSQL.Api/Controllers/ApiController.cs

@@ -4,16 +4,16 @@
 using System;
 using System.Linq;
 
-namespace MiniSQL.Api
+namespace MiniSQL.Api.Controllers
 {
-    public class Api : IApi
+    public class ApiController : IApi
     {
 
         private readonly IInterpreter _interpreter;
         private readonly ICatalogManager _catalogManager;
         private readonly IRecordManager _recordManager;
 
-        public Api(IInterpreter interpreter, ICatalogManager catalogManager, IRecordManager recordManager)
+        public ApiController(IInterpreter interpreter, ICatalogManager catalogManager, IRecordManager recordManager)
         {
             _catalogManager = catalogManager;
             _interpreter = interpreter;

src/MiniSQL.Api/Program.cs

@@ -1,50 +1,12 @@
 using System;
-using System.Collections.Generic;
-using System.Diagnostics;
-using System.IO;
-using System.Text;
-using MiniSQL.Api.Controllers;
-using MiniSQL.BufferManager.Controllers;
-using MiniSQL.BufferManager.Models;
-using MiniSQL.CatalogManager;
-using MiniSQL.IndexManager.Controllers;
-using MiniSQL.IndexManager.Interfaces;
-using MiniSQL.Interpreter;
-using MiniSQL.Library.Interfaces;
-using MiniSQL.Library.Models;
-using MiniSQL.RecordManager;
 
 namespace MiniSQL.Api
 {
     class Program
     {
         static void Main(string[] args)
         {
-            UseDatabase("test");
-        }
-        
-        public static void UseDatabase(string databaseName)
-        {
-            // init
-            string dbPath = $"./{databaseName}.minidb";
-            Pager pager = new Pager(dbPath, 1024 * 8, 400);
-            FreeList freeList = new FreeList(pager);
-            IIndexManager bTreeController = new BTreeController(pager, freeList, 40);
-            IInterpreter interpreter = new Parsing();
-            ICatalogManager catalogManager = new Catalog(databaseName);
-            IRecordManager recordManager = new RecordContext(pager, bTreeController);
-            IApi api = new Api(interpreter, catalogManager, recordManager);
-
-            View view = new View(
-                bTreeController,
-                interpreter,
-                catalogManager,
-                recordManager,
-                api,
-                pager
-            );
-            view.Interactive();  
-            
+            Console.WriteLine("Hello world");
         }
     }
 }

src/MiniSQL.BufferManager/Controllers/Pager.cs

@@ -150,6 +150,8 @@ public void ReadPage(MemoryPage page)
                 // remove LRU if out of limit
                 if (this.Pages.Count >= this.InMemoryPageCountLimit)
                     RemoveLRUPage();
+                if (this.Pages.Count >= this.InMemoryPageCountLimit)
+                    throw new Exception("Race condition!");
 
                 page.Core = new MemoryPage.MemoryPageCore(this, page.PageNumber);
                 page.Core.data = new byte[this.PageSize];
@@ -187,6 +189,8 @@ public void Close()
             }
         }
 
+        // write back dirty pages without closing connection to the file system
+        // the changes will not immediately affect the file in secondary memory (the disk)
         public void CleanAllPagesFromMainMemory()
         {
             lock (this)

src/MiniSQL.Startup/Controllers/DatabaseController.cs

@@ -0,0 +1,30 @@
+
+using MiniSQL.Api.Controllers;
+using MiniSQL.BufferManager.Controllers;
+using MiniSQL.CatalogManager;
+using MiniSQL.IndexManager.Controllers;
+using MiniSQL.IndexManager.Interfaces;
+using MiniSQL.Interpreter;
+using MiniSQL.Library.Interfaces;
+using MiniSQL.RecordManager;
+
+namespace MiniSQL.Startup.Controllers
+{
+    public class DatabaseController
+    {
+        public (IApi, Pager) UseDatabase(string databaseName)
+        {
+            // init
+            string dbPath = $"./{databaseName}.minidb";
+            Pager pager = new Pager(dbPath, 1024 * 8, 400);
+            FreeList freeList = new FreeList(pager);
+            IIndexManager bTreeController = new BTreeController(pager, freeList, 40);
+            IInterpreter interpreter = new Parsing();
+            ICatalogManager catalogManager = new Catalog(databaseName);
+            IRecordManager recordManager = new RecordContext(pager, bTreeController);
+            IApi api = new ApiController(interpreter, catalogManager, recordManager);
+            
+            return (api, pager);
+        }
+    }
+}

src/MiniSQL.Api/Controllers/View.cs renamed to src/MiniSQL.Startup/Controllers/View.cs

@@ -1,25 +1,26 @@
 using System;
 using System.Collections.Generic;
 using System.Diagnostics;
+using System.IO;
 using System.Text;
+using System.Text.RegularExpressions;
 using MiniSQL.BufferManager.Controllers;
 using MiniSQL.IndexManager.Interfaces;
 using MiniSQL.Library.Interfaces;
 using MiniSQL.Library.Models;
 
-namespace MiniSQL.Api.Controllers
+namespace MiniSQL.Startup.Controllers
 {
     public class View
     {
-        private readonly IIndexManager _bTreeController;
-        private readonly IInterpreter _interpreter;
-        private readonly ICatalogManager _catalogManager;
-        private readonly IRecordManager _recordManager;
-        private readonly IApi _api;
-        private readonly Pager _pager;
+        private bool isUsingDatabase = false;
+        private string nameOfDatabaseInUse;
+        private IApi _api;
+        private Pager _pager;
+        private readonly DatabaseController _databaseController;
         private bool isCtrlC = false;
 
-        public View(IIndexManager bTreeController, IInterpreter interpreter, ICatalogManager catalogManager, IRecordManager recordManager, IApi api, Pager pager)
+        public View(DatabaseController databaseController)
         {
             // ensure writing back when ctrl-c
             Console.CancelKeyPress += OnExit;
@@ -28,14 +29,34 @@ public View(IIndexManager bTreeController, IInterpreter interpreter, ICatalogMan
             Console.WriteLine();
             Console.WriteLine("Hello MiniSQL!");
             Console.WriteLine();
-            
+
+            _databaseController = databaseController;
+        }
+
+        // TODO: wrap this to a class
+        private void ChangeContext(string newDatabaseName)
+        {
+            if (isUsingDatabase)
+            {
+                _pager.Close();
+            }
             // init
-            _pager = pager;
-            _bTreeController = bTreeController;
-            _interpreter = interpreter;
-            _catalogManager = catalogManager;
-            _recordManager = recordManager;
-            _api = api;
+            this.isUsingDatabase = true;
+            this.nameOfDatabaseInUse = newDatabaseName;
+            (_api, _pager) = _databaseController.UseDatabase(newDatabaseName);
+        }
+
+        // TODO: wrap this to a class
+        private void DropDatabase(string databaseName)
+        {
+            if (nameOfDatabaseInUse == databaseName)
+            {
+                _pager.Close();
+                isUsingDatabase = false;
+            }
+            File.Delete($"{databaseName}.minidb");
+            File.Delete($"{databaseName}.indices.txt");
+            File.Delete($"{databaseName}.tables.txt");
         }
 
         // interactive(blocking) view of the whole solution 
@@ -68,6 +89,26 @@ public void Interactive()
                     isExit = true;
                     continue;
                 }
+                // use database
+                if (Regex.IsMatch(line, @"(?i)\s*use\s*database\s*.*(?-i)"))
+                {
+                    string databaseName = line.Split(new string[] { " ", "\n" }, StringSplitOptions.RemoveEmptyEntries)[2].TrimEnd(';');
+                    ChangeContext(databaseName);
+                    continue;
+                }
+                // drop database
+                if (Regex.IsMatch(line, @"(?i)\s*drop\s*database\s*.*(?-i)"))
+                {
+                    string databaseName = line.Split(new string[] { " ", "\n" }, StringSplitOptions.RemoveEmptyEntries)[2].TrimEnd(';');
+                    DropDatabase(databaseName);
+                    continue;
+                }
+                if (!this.isUsingDatabase)
+                {
+                    // WORKAROUND
+                    Console.WriteLine("[Error] No database in use");
+                    continue;
+                }
                 // flush all the dirty pages back to secondary memory and clean the main memory out of any page
                 if (line == "flush")
                 {
@@ -137,7 +178,8 @@ public void Interactive()
                 input.Clear();
             }
             // save database file
-            _pager.Close();
+            if (this.isUsingDatabase)
+                _pager.Close();
         }
 
         // BUG: NOT WORKING
@@ -247,4 +289,4 @@ private static void Print(string toPrint, ConsoleColor color)
             Console.ForegroundColor = defaultColor;
         }
     }
-}
+}

src/MiniSQL.Startup/MiniSQL.Startup.csproj

@@ -0,0 +1,17 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <ItemGroup>
+    <ProjectReference Include="..\MiniSQL.Library\MiniSQL.Library.csproj" />
+    <ProjectReference Include="..\MiniSQL.Api\MiniSQL.Api.csproj" />
+    <ProjectReference Include="..\MiniSQL.Interpreter\MiniSQL.Interpreter.csproj" />
+    <ProjectReference Include="..\MiniSQL.CatalogManager\MiniSQL.CatalogManager.csproj" />
+    <ProjectReference Include="..\MiniSQL.IndexManager\MiniSQL.IndexManager.csproj" />
+    <ProjectReference Include="..\MiniSQL.RecordManager\MiniSQL.RecordManager.csproj" />
+  </ItemGroup>
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>netcoreapp3.1</TargetFramework>
+  </PropertyGroup>
+
+</Project>

src/MiniSQL.Startup/Program.cs

@@ -0,0 +1,14 @@
+using MiniSQL.Startup.Controllers;
+
+namespace MiniSQL.Startup
+{
+    class Program
+    {
+        static void Main(string[] args)
+        {
+            DatabaseController controller = new DatabaseController();
+            View view = new View(controller);
+            view.Interactive();
+        }
+    }
+}