Added: Savepoint support

CHANGELOG.md

@@ -185,4 +185,7 @@ Version 3.1.0 - August 11 2020
 
 Version 3.1.1 - August 19 2020
 - #292 Fix compilation if using SQLITE_HAS_CODEC from sum01/fix_sqlcipher_compile
-- #293 Remove FindSQLiteCpp.cmake from sum01/fix_283
+- #293 Remove FindSQLiteCpp.cmake from sum01/fix_283
+
+Version 3.2.0 - September 10 2020
+- Added Savepoint support

CMakeLists.txt

@@ -103,6 +103,7 @@ set(SQLITECPP_SRC
  ${PROJECT_SOURCE_DIR}/src/Column.cpp
  ${PROJECT_SOURCE_DIR}/src/Database.cpp
  ${PROJECT_SOURCE_DIR}/src/Exception.cpp
+ ${PROJECT_SOURCE_DIR}/src/Savepoint.cpp
  ${PROJECT_SOURCE_DIR}/src/Statement.cpp
  ${PROJECT_SOURCE_DIR}/src/Transaction.cpp
 )
@@ -116,6 +117,7 @@ set(SQLITECPP_INC
  ${PROJECT_SOURCE_DIR}/include/SQLiteCpp/Column.h
  ${PROJECT_SOURCE_DIR}/include/SQLiteCpp/Database.h
  ${PROJECT_SOURCE_DIR}/include/SQLiteCpp/Exception.h
+ ${PROJECT_SOURCE_DIR}/include/SQLiteCpp/Savepoint.h
  ${PROJECT_SOURCE_DIR}/include/SQLiteCpp/Statement.h
  ${PROJECT_SOURCE_DIR}/include/SQLiteCpp/Transaction.h
  ${PROJECT_SOURCE_DIR}/include/SQLiteCpp/VariadicBind.h
@@ -127,6 +129,7 @@ source_group(include FILES ${SQLITECPP_INC})
 set(SQLITECPP_TESTS
  tests/Column_test.cpp
  tests/Database_test.cpp
+ tests/Savepoint_test.cpp
  tests/Statement_test.cpp
  tests/Backup_test.cpp
  tests/Transaction_test.cpp

include/SQLiteCpp/Savepoint.h

@@ -0,0 +1,94 @@
+/**
+ * @file    Savepoint.h
+ * @ingroup SQLiteCpp
+ * @brief   A Savepoint is a way to group multiple SQL statements into an atomic
+ * secured operation. Similar to a transaction while allowing child savepoints.
+ *
+ * Copyright (c) 2020 Kelvin Hammond ([email protected])
+ *
+ * Distributed under the MIT License (MIT) (See accompanying file LICENSE.txt or
+ * copy at http://opensource.org/licenses/MIT)
+ */
+#pragma once
+
+#include <SQLiteCpp/Exception.h>
+
+namespace SQLite {
+
+// Foward declaration
+class Database;
+
+/**
+ * @brief RAII encapsulation of a SQLite Savepoint.
+ *
+ * A Savepoint is a way to group multiple SQL statements into an atomic
+ * secureced operation; either it succeeds, with all the changes commited to the
+ * database file, or if it fails, all the changes are rolled back to the initial
+ * state at the start of the savepoint.
+ *
+ * This method also offers big performances improvements compared to
+ * individually executed statements.
+ *
+ * Caveats:
+ *
+ * 1) Calling COMMIT or commiting a parent transaction or RELEASE on a parent
+ * savepoint will cause this savepoint to be released.
+ *
+ * 2) Calling ROLLBACK or rolling back a parent savepoint will cause this
+ * savepoint to be rolled back.
+ *
+ * 3) This savepoint is not saved to the database until this and all savepoints
+ * or transaction in the savepoint stack have been released or commited.
+ *
+ * See also: https://sqlite.org/lang_savepoint.html
+ *
+ * Thread-safety: a Transaction object shall not be shared by multiple threads,
+ * because:
+ *
+ * 1) in the SQLite "Thread Safe" mode, "SQLite can be safely used by multiple
+ * threads provided that no single database connection is used simultaneously in
+ * two or more threads."
+ *
+ * 2) the SQLite "Serialized" mode is not supported by SQLiteC++, because of the
+ * way it shares the underling SQLite precompiled statement in a custom shared
+ * pointer (See the inner class "Statement::Ptr").
+ */
+
+class Savepoint {
+   public:
+    /**
+     * @brief Begins the SQLite savepoint
+     *
+     * @param[in] aDatabase the SQLite Database Connection
+     * @param[in] aName the name of the Savepoint
+     *
+     * Exception is thrown in case of error, then the Savepoint is NOT
+     * initiated.
+     */
+    Savepoint(Database& aDatabase, std::string name);
+
+    // Savepoint is non-copyable
+    Savepoint(const Savepoint&) = delete;
+    Savepoint& operator=(const Savepoint&) = delete;
+
+    /**
+     * @brief Safely rollback the savepoint if it has not been commited.
+     */
+    ~Savepoint();
+
+    /**
+     * @brief Commit and release the savepoint.
+     */
+    void release();
+
+    /**
+     * @brief Rollback the savepoint
+     */
+    void rollback();
+
+   private:
+    Database& mDatabase;  ///< Reference to the SQLite Database Connection
+    std::string msName;   ///< Name of the Savepoint
+    bool mbReleased;      ///< True when release has been called
+};
+}  // namespace SQLite

src/Savepoint.cpp

@@ -0,0 +1,65 @@
+/**
+ * @file    Savepoint.cpp
+ * @ingroup SQLiteCpp
+ * @brief   A Savepoint is a way to group multiple SQL statements into an atomic
+ * secured operation. Similar to a transaction while allowing child savepoints.
+ *
+ * Copyright (c) 2020 Kelvin Hammond ([email protected])
+ *
+ * Distributed under the MIT License (MIT) (See accompanying file LICENSE.txt or
+ * copy at http://opensource.org/licenses/MIT)
+ */
+
+#include <SQLiteCpp/Assertion.h>
+#include <SQLiteCpp/Database.h>
+#include <SQLiteCpp/Savepoint.h>
+#include <SQLiteCpp/Statement.h>
+
+namespace SQLite {
+
+// Begins the SQLite savepoint
+Savepoint::Savepoint(Database& aDatabase, std::string aName)
+    : mDatabase(aDatabase), msName(aName), mbReleased(false) {
+    // workaround because you cannot bind to SAVEPOINT
+    // escape name for use in query
+    Statement stmt(mDatabase, "SELECT quote(?)");
+    stmt.bind(1, msName);
+    stmt.executeStep();
+    msName = stmt.getColumn(0).getText();
+
+    mDatabase.exec(std::string("SAVEPOINT ") + msName);
+}
+
+// Safely rollback the savepoint if it has not been committed.
+Savepoint::~Savepoint() {
+    if (!mbReleased) {
+        try {
+            rollback();
+        } catch (SQLite::Exception&) {
+            // Never throw an exception in a destructor: error if already rolled
+            // back or released, but no harm is caused by this.
+        }
+    }
+}
+
+// Release the savepoint and commit
+void Savepoint::release() {
+    if (!mbReleased) {
+        mDatabase.exec(std::string("RELEASE SAVEPOINT ") + msName);
+        mbReleased = true;
+    } else {
+        throw SQLite::Exception("Savepoint already released or rolled back.");
+    }
+}
+
+// Rollback the savepoint
+void Savepoint::rollback() {
+    if (!mbReleased) {
+        mDatabase.exec(std::string("ROLLBACK TO SAVEPOINT ") + msName);
+        mbReleased = true;
+    } else {
+        throw SQLite::Exception("Savepoint already released or rolled back.");
+    }
+}
+
+}  // namespace SQLite

tests/Savepoint_test.cpp

@@ -0,0 +1,107 @@
+/**
+ * @file    Savepoint_test.cpp
+ * @ingroup tests
+ * @brief   Test of a SQLite Savepoint.
+ *
+ * Copyright (c) 2020 Kelvin Hammond ([email protected])
+ *
+ * Distributed under the MIT License (MIT) (See accompanying file LICENSE.txt or
+ * copy at http://opensource.org/licenses/MIT)
+ */
+
+#include <SQLiteCpp/Database.h>
+#include <SQLiteCpp/Exception.h>
+#include <SQLiteCpp/Savepoint.h>
+#include <SQLiteCpp/Statement.h>
+#include <SQLiteCpp/Transaction.h>
+#include <gtest/gtest.h>
+
+#include <cstdio>
+
+TEST(Savepoint, commitRollback) {
+    // Create a new database
+    SQLite::Database db(":memory:",
+                        SQLite::OPEN_READWRITE | SQLite::OPEN_CREATE);
+    EXPECT_EQ(SQLite::OK, db.getErrorCode());
+
+    {
+        // Begin savepoint
+        SQLite::Savepoint savepoint(db, "sp1");
+
+        EXPECT_EQ(
+            0,
+            db.exec("CREATE TABLE test (id INTEGER PRIMARY KEY, value TEXT)"));
+        EXPECT_EQ(SQLite::OK, db.getErrorCode());
+
+        // Insert a first valu
+        EXPECT_EQ(1, db.exec("INSERT INTO test VALUES (NULL, 'first')"));
+        EXPECT_EQ(1, db.getLastInsertRowid());
+
+        // release savepoint
+        savepoint.release();
+
+        // Commit again throw an exception
+        EXPECT_THROW(savepoint.release(), SQLite::Exception);
+    }
+
+    // Auto rollback if no release() before the end of scope
+    {
+        // Begin savepoint
+        SQLite::Savepoint savepoint(db, "sp2");
+
+        // Insert a second value (that will be rollbacked)
+        EXPECT_EQ(1, db.exec("INSERT INTO test VALUES (NULL, 'third')"));
+        EXPECT_EQ(2, db.getLastInsertRowid());
+
+        // end of scope: automatic rollback
+    }
+
+    // Auto rollback of a transaction on error / exception
+    try {
+        // Begin savepoint
+        SQLite::Savepoint savepoint(db, "sp3");
+
+        // Insert a second value (that will be rollbacked)
+        EXPECT_EQ(1, db.exec("INSERT INTO test VALUES (NULL, 'second')"));
+        EXPECT_EQ(2, db.getLastInsertRowid());
+
+        // Execute with an error => exception with auto-rollback
+        db.exec(
+            "DesiredSyntaxError to raise an exception to rollback the "
+            "transaction");
+
+        GTEST_FATAL_FAILURE_("we should never get there");
+        savepoint.release();  // We should never get there
+    } catch (std::exception& e) {
+        std::cout << "SQLite exception: " << e.what() << std::endl;
+        // expected error, see above
+    }
+
+    // Double rollback with a manual command before the end of scope
+    {
+        // Begin savepoint
+        SQLite::Savepoint savepoint(db, "sp4");
+
+        // Insert a second value (that will be rollbacked)
+        EXPECT_EQ(1, db.exec("INSERT INTO test VALUES (NULL, 'third')"));
+        EXPECT_EQ(2, db.getLastInsertRowid());
+
+        // Execute a manual rollback (no real use case I can think of, so no
+        // rollback() method)
+        db.exec("ROLLBACK");
+
+        // end of scope: the automatic rollback should not raise an error
+        // because it is harmless
+    }
+
+    // Check the results (expect only one row of result, as all other one have
+    // been rollbacked)
+    SQLite::Statement query(db, "SELECT * FROM test");
+    int nbRows = 0;
+    while (query.executeStep()) {
+        nbRows++;
+        EXPECT_EQ(1, query.getColumn(0).getInt());
+        EXPECT_STREQ("first", query.getColumn(1).getText());
+    }
+    EXPECT_EQ(1, nbRows);
+}