Replace Database::backup() "C" implementation by calling the Backup class

CHANGELOG.md

@@ -161,4 +161,5 @@ Version 3.0.0 - January 1 2020
 - CMake 3.1 minimum
 - Visual Studio 2015 minimum
 - Googletest 1.10
-- Remove Statement::isOk() deprecated in 2.2.0 when renamed to Statement::hasRow()
+- Remove Statement::isOk() deprecated in 2.2.0 when renamed to Statement::hasRow()
+- Replace Database::backup() "C" implementation by calling the Backup class

include/SQLiteCpp/Backup.h

@@ -27,16 +27,8 @@ namespace SQLite
  * A Backup object is used to backup a source database file to a destination database file
  * in a safe and online way.
  *
- * Resource Acquisition Is Initialization (RAII) means that the Backup Resource
- * is allocated in the constructor and released in the destructor, so that there is
- * no need to worry about memory management or the validity of the underlying SQLite Backup.
- *
- * Thread-safety: a Backup 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").
+ * See also the a reference implementation of live backup taken from the official site:
+ * https://www.sqlite.org/backup.html
  */
 class Backup
 {

include/SQLiteCpp/Database.h

@@ -489,9 +489,9 @@ public:
      * into the "main" database of open database connection, or to save the current
      * contents of the database into a database file on disk.
      *
-     * @return SQLITE_OK on success or an error code from SQLite.
+     * @throw SQLite::Exception in case of error
      */
-    int backup(const char* zFilename, BackupType type);
+    void backup(const char* apFilename, BackupType aType);
 
     /**
      * @brief Check if aRet equal SQLITE_OK, else throw a SQLite::Exception with the SQLite error message

src/Database.cpp

@@ -11,6 +11,7 @@
 #include <SQLiteCpp/Database.h>
 
 #include <SQLiteCpp/Assertion.h>
+#include <SQLiteCpp/Backup.h>
 #include <SQLiteCpp/Exception.h>
 #include <SQLiteCpp/Statement.h>
 
@@ -405,49 +406,20 @@ Header Database::getHeaderInfo(const std::string& aFilename)
     return h;
 }
 
+void Database::backup(const char* apFilename, BackupType aType)
+{
+    // Open the database file identified by apFilename
+    Database otherDatabase(apFilename, SQLite::OPEN_READWRITE | SQLite::OPEN_CREATE);
 
-// This is a reference implementation of live backup taken from the official sit:
-// https://www.sqlite.org/backup.html
+    // For a 'Save' operation, data is copied from the current Database to the other. A 'Load' is the reverse.
+    Database& src = (aType == Save ? *this : otherDatabase);
+    Database& dest = (aType == Save ? otherDatabase : *this);
 
-int Database::backup(const char* zFilename, BackupType type) {
-    /* Open the database file identified by zFilename. Exit early if this fails. */
-    sqlite3* pFile;
-    int rc = sqlite3_open(zFilename, &pFile);
-    if (rc == SQLITE_OK)
-    {
-        /* If this is a 'load' operation (isSave==0), then data is copied
-        ** from the database file just opened to database mpSQLite.
-        ** Otherwise, if this is a 'save' operation (isSave==1), then data
-        ** is copied from mpSQLite to pFile.  Set the variables pFrom and
-        ** pTo accordingly. */
-        sqlite3* pFrom = (type == Save ? getHandle() : pFile);
-        sqlite3* pTo = (type == Save ? pFile : getHandle());
+    // Set up the backup procedure to copy between the "main" databases of each connection
+    Backup bkp(dest, src);
+    bkp.executeStep(); // Execute all steps at once
 
-        /* Set up the backup procedure to copy from the "main" database of
-        ** connection pFile to the main database of connection mpSQLite.
-        ** If something goes wrong, pBackup will be set to NULL and an error
-        ** code and message left in connection pTo.
-        **
-        ** If the backup object is successfully created, call backup_step()
-        ** to copy data from pFile to mpSQLite. Then call backup_finish()
-        ** to release resources associated with the pBackup object.  If an
-        ** error occurred, then an error code and message will be left in
-        ** connection pTo. If no error occurred, then the error code belonging
-        ** to pTo is set to SQLITE_OK.
-        */
-        sqlite3_backup *pBackup = sqlite3_backup_init(pTo, "main", pFrom, "main");
-        if (pBackup)
-        {
-            sqlite3_backup_step(pBackup, -1);
-            sqlite3_backup_finish(pBackup);
-        }
-        rc = sqlite3_errcode(pTo);
-    }
-
-    /* Close the database connection opened on database file zFilename
-    ** and return the result of this function. */
-    sqlite3_close(pFile);
-    return rc;
+    // RAII Finish Backup an Close the other Database
 }
 
 }  // namespace SQLite

tests/Database_test.cpp

@@ -131,7 +131,7 @@ TEST(Database, inMemory)
     } // Close an destroy DB
 }
 
-TEST(Database, import_export)
+TEST(Database, backup)
 {
     // Create a new in-memory database
     SQLite::Database db(":memory:", SQLite::OPEN_READWRITE);
@@ -141,14 +141,14 @@ TEST(Database, import_export)
 
     // Export the data into a file
     remove("backup");
-    EXPECT_EQ(db.backup("backup", SQLite::Database::Save), SQLITE_OK);
+    EXPECT_NO_THROW(db.backup("backup", SQLite::Database::Save));
 
     // Trash the table
     db.exec("DROP TABLE test;");
     EXPECT_FALSE(db.tableExists("test"));
 
     // Import the data back from the file
-    EXPECT_EQ(db.backup("backup", SQLite::Database::Load), SQLITE_OK);
+    EXPECT_NO_THROW(db.backup("backup", SQLite::Database::Load));
 
     EXPECT_TRUE(db.tableExists("test"));
 }