Automatically dispose a database backup if either the src or dest dbs is disposed.

Author: bordoley

SQLitePCL.pretty.tests/ImplementationTests.cs

@@ -38,6 +38,8 @@ public void TestDispose()
                     db.Execute("INSERT INTO foo (x) VALUES (?);", i);
                 }
 
+                IDatabaseBackup notDisposedBackup;
+                
                 using (var db2 = SQLite3.Open(":memory:"))
                 {
                     var backup = db.BackupInit("main", db2, "main");
@@ -46,7 +48,15 @@ public void TestDispose()
                     Assert.Throws<ObjectDisposedException>(() => { var x = backup.PageCount; });
                     Assert.Throws<ObjectDisposedException>(() => { var x = backup.RemainingPages; });
                     Assert.Throws<ObjectDisposedException>(() => { backup.Step(1); });
+
+                    notDisposedBackup = db.BackupInit("main", db2, "main");
                 }
+
+                // Ensure diposing the database connection automatically disposes the backup as well.
+                Assert.Throws<ObjectDisposedException>(() => { var x = notDisposedBackup.PageCount; });
+
+                // Test double disposing doesn't result in exceptions.
+                notDisposedBackup.Dispose();
             }
         }
 

SQLitePCL.pretty/DatabaseConnection.cs

@@ -960,7 +960,7 @@ public IDatabaseBackup BackupInit(string dbName, SQLiteDatabaseConnection destCo
             if (disposed) { throw new ObjectDisposedException(this.GetType().FullName); }
 
             sqlite3_backup backup = raw.sqlite3_backup_init(destConn.db, destDbName, db, dbName);
-            var result = new DatabaseBackupImpl(backup, this);
+            var result = new DatabaseBackupImpl(backup, this, destConn);
             return result;
         }
 

SQLitePCL.pretty/Implementation.cs

@@ -26,18 +26,21 @@ namespace SQLitePCL.pretty
     internal sealed class DatabaseBackupImpl : IDatabaseBackup
     {
         private readonly sqlite3_backup backup;
-        private readonly SQLiteDatabaseConnection db;
+        private readonly SQLiteDatabaseConnection srcDb;
+        private readonly SQLiteDatabaseConnection destDb;
         private readonly EventHandler dbDisposing;
 
         private bool disposed = false;
 
-        internal DatabaseBackupImpl(sqlite3_backup backup, SQLiteDatabaseConnection db)
+        internal DatabaseBackupImpl(sqlite3_backup backup, SQLiteDatabaseConnection srcDb, SQLiteDatabaseConnection  destDb)
         {
             this.backup = backup;
-            this.db = db;
+            this.srcDb = srcDb;
+            this.destDb = destDb;
 
             this.dbDisposing = (o, e) => Dispose();
-            this.db.Disposing += dbDisposing;
+            this.srcDb.Disposing += dbDisposing;
+            this.destDb.Disposing += dbDisposing;
         }
 
         public int PageCount
@@ -68,7 +71,8 @@ public void Dispose()
             // FIXME: What to do about errors?
             raw.sqlite3_backup_finish(backup);
 
-            db.Disposing -= dbDisposing;
+            srcDb.Disposing -= dbDisposing;
+            destDb.Disposing -= dbDisposing;
         }
 
         public bool Step(int nPages)