Merge pull request #36 from iwongu/backup

Supports backup methods in database class.

Author: iwongu

README.md

@@ -118,6 +118,26 @@ sqlite3pp::query qry(
   "SELECT epi.* FROM episodes epi, test.contacts con WHERE epi.id = con.id");
 ```
 
+## backup
+
+```cpp
+sqlite3pp::database db("test.db");
+sqlite3pp::database backupdb("backup.db");
+
+db.backup(backupdb);
+```
+
+```cpp
+db.backup(
+  backupdb,
+  [](int pagecount, int remaining, int rc) {
+    cout << pagecount << "/" << remaining << endl;
+    if (rc == SQLITE_OK || rc == SQLITE_BUSY || rc == SQLITE_LOCKED) {
+      // sleep or do nothing.
+    }
+  });
+```
+
 ## callback
 
 ```cpp

headeronly_src/sqlite3pp.h

@@ -78,6 +78,7 @@ namespace sqlite3pp
     using rollback_handler = std::function<void ()>;
     using update_handler = std::function<void (int, char const*, char const*, long long int)>;
     using authorize_handler = std::function<int (int, char const*, char const*, char const*, char const*)>;
+    using backup_handler = std::function<void (int, int, int)>;
 
     explicit database(char const* dbname = nullptr, int flags = SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE, const char* vfs = nullptr);
 
@@ -92,6 +93,9 @@ namespace sqlite3pp
     int attach(char const* dbname, char const* name);
     int detach(char const* name);
 
+    int backup(database& destdb, backup_handler h = {});
+    int backup(char const* dbname, database& destdb, char const* destdbname, backup_handler h, int step_page = 5);
+
     long long int last_insert_rowid() const;
 
     int enable_foreign_keys(bool enable = true);

headeronly_src/sqlite3pp.ipp

@@ -132,6 +132,28 @@ namespace sqlite3pp
     return executef("DETACH '%q'", name);
   }
 
+  inline int database::backup(database& destdb, backup_handler h)
+  {
+    return backup("main", destdb, "main", h);
+  }
+
+  inline int database::backup(char const* dbname, database& destdb, char const* destdbname, backup_handler h, int step_page)
+  {
+    sqlite3_backup* bkup = sqlite3_backup_init(destdb.db_, destdbname, db_, dbname);
+    if (!bkup) {
+      return error_code();
+    }
+    auto rc = SQLITE_OK;
+    do {
+      rc = sqlite3_backup_step(bkup, step_page);
+      if (h) {
+	h(sqlite3_backup_remaining(bkup), sqlite3_backup_pagecount(bkup), rc);
+      }
+    } while (rc == SQLITE_OK || rc == SQLITE_BUSY || rc == SQLITE_LOCKED);
+    sqlite3_backup_finish(bkup);
+    return rc;
+  }
+
   inline void database::set_busy_handler(busy_handler h)
   {
     bh_ = h;

src/sqlite3pp.cpp

@@ -134,6 +134,28 @@ namespace sqlite3pp
     return executef("DETACH '%q'", name);
   }
 
+  int database::backup(database& destdb, backup_handler h)
+  {
+    return backup("main", destdb, "main", h);
+  }
+
+  int database::backup(char const* dbname, database& destdb, char const* destdbname, backup_handler h, int step_page)
+  {
+    sqlite3_backup* bkup = sqlite3_backup_init(destdb.db_, destdbname, db_, dbname);
+    if (!bkup) {
+      return error_code();
+    }
+    auto rc = SQLITE_OK;
+    do {
+      rc = sqlite3_backup_step(bkup, step_page);
+      if (h) {
+	h(sqlite3_backup_remaining(bkup), sqlite3_backup_pagecount(bkup), rc);
+      }
+    } while (rc == SQLITE_OK || rc == SQLITE_BUSY || rc == SQLITE_LOCKED);
+    sqlite3_backup_finish(bkup);
+    return rc;
+  }
+
   void database::set_busy_handler(busy_handler h)
   {
     bh_ = h;

src/sqlite3pp.h

@@ -79,6 +79,7 @@ namespace sqlite3pp
     using rollback_handler = std::function<void ()>;
     using update_handler = std::function<void (int, char const*, char const*, long long int)>;
     using authorize_handler = std::function<int (int, char const*, char const*, char const*, char const*)>;
+    using backup_handler = std::function<void (int, int, int)>;
 
     explicit database(char const* dbname = nullptr, int flags = SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE, const char* vfs = nullptr);
 
@@ -93,6 +94,9 @@ namespace sqlite3pp
     int attach(char const* dbname, char const* name);
     int detach(char const* name);
 
+    int backup(database& destdb, backup_handler h = {});
+    int backup(char const* dbname, database& destdb, char const* destdbname, backup_handler h, int step_page = 5);
+
     long long int last_insert_rowid() const;
 
     int enable_foreign_keys(bool enable = true);

test/testbackup.cpp

@@ -0,0 +1,25 @@
+#include <iostream>
+#include "sqlite3pp.h"
+
+using namespace std;
+
+int main()
+{
+  try {
+    sqlite3pp::database db("test.db");
+    sqlite3pp::database backupdb("backup.db");
+
+    db.backup(
+      backupdb,
+      [](int pagecount, int remaining, int rc) {
+        cout << pagecount << "/" << remaining << endl;
+        if (rc == SQLITE_OK || rc == SQLITE_BUSY || rc == SQLITE_LOCKED) {
+          // sleep(250);
+        }
+      });
+  }
+  catch (exception& ex) {
+    cout << ex.what() << endl;
+  }
+
+}