Add transaction support, last-insert-rowid, changes; fix open leak

sqlite3.carp

@@ -170,17 +170,15 @@ primitive Carp types can be casted to appropriate SQLite types by using the
     "SQLite3_exec_c")
   (private error-)
   (hidden error-)
-  (register error- (Fn [SQLite] (Ptr CChar)) "SQLite3_error")
+  (register error- (Fn [SQLite] String) "SQLite3_error_and_close")
 
   (doc open "opens a database with the filename `s`.
 
 If it fails, we return an error message using `Result.Error`.")
   (defn open [s]
     (let [db (SQLite3.init)
           res (open- &db (cstr s))]
-      (if (= res sql_ok)
-        (Result.Success db)
-        (Result.Error (from-cstr (error- db))))))
+      (if (= res sql_ok) (Result.Success db) (Result.Error (error- db)))))
 
   (doc query "queries the database `db` using the query `s` and the parameters
 `p`.
@@ -195,7 +193,71 @@ If it fails, we return an error message using `Result.Error`.")
         (Result.Error (from-cstr (SQLiteRes.error r))))))
 
   (doc close "closes a database.")
-  (register close (Fn [SQLite] ()) "SQLite3_close_c"))
+  (register close (Fn [SQLite] ()) "SQLite3_close_c")
+
+  (doc last-insert-rowid "returns the row ID of the last successful INSERT.")
+  (register last-insert-rowid (Fn [&SQLite] Long) "SQLite3_last_insert_rowid")
+
+  (doc changes "returns the number of rows modified by the last INSERT, UPDATE,
+or DELETE.")
+  (register changes (Fn [&SQLite] Int) "SQLite3_changes")
+
+  (doc begin "begins a transaction.")
+  (defn begin [db]
+    (match (query db "BEGIN TRANSACTION;" &[])
+      (Result.Success _) (Result.Success ())
+      (Result.Error e) (Result.Error e)))
+
+  (doc commit "commits the current transaction.")
+  (defn commit [db]
+    (match (query db "COMMIT;" &[])
+      (Result.Success _) (Result.Success ())
+      (Result.Error e) (Result.Error e)))
+
+  (doc rollback "rolls back the current transaction.")
+  (defn rollback [db]
+    (match (query db "ROLLBACK;" &[])
+      (Result.Success _) (Result.Success ())
+      (Result.Error e) (Result.Error e)))
+
+  (doc with-transaction "executes `body` inside a transaction. If `body`
+evaluates to a `Result.Error`, the transaction is rolled back; otherwise it is
+committed. Returns the result of `body`, or the error from `begin`/`commit`
+if those fail.
+
+Example:
+```
+(SQLite3.with-transaction &db
+  (do
+    (ignore (SQLite3.query &db \"INSERT INTO t VALUES (1);\" &[]))
+    (SQLite3.query &db \"SELECT * FROM t;\" &[])))
+```")
+  (defmacro with-transaction [db body]
+    (list 'let
+          (array '__wtx_begin (list 'SQLite3.begin db))
+          (list 'match
+                '__wtx_begin
+                (list 'Result.Error '__wtx_err)
+                (list 'Result.Error '__wtx_err)
+                (list 'Result.Success '_)
+                (list 'let
+                      (array '__wtx_result body)
+                      (list 'match
+                            '__wtx_result
+                            (list 'Result.Error '__wtx_berr)
+                            (list 'do
+                                  (list 'ignore (list 'SQLite3.rollback db))
+                                  (list 'Result.Error '__wtx_berr))
+                            (list 'Result.Success '__wtx_val)
+                            (list 'match
+                                  (list 'SQLite3.commit db)
+                                  (list 'Result.Error '__wtx_cerr)
+                                  (list 'do
+                                        (list 'ignore
+                                              (list 'SQLite3.rollback db))
+                                        (list 'Result.Error '__wtx_cerr))
+                                  (list 'Result.Success '_)
+                                  (list 'Result.Success '__wtx_val))))))))
 
 (definterface to-sqlite3 (Fn [a] SQLite3.Type))
 

sqlite3_helper.h

@@ -293,6 +293,19 @@ void SQLite3_close_c(SQLite db) {
   sqlite3_close_v2(db.handle);
 }
 
-char* SQLite3_error(SQLite db) {
-  return (char*)sqlite3_errmsg(db.handle);
+int64_t SQLite3_last_insert_rowid(SQLite* db) {
+  return (int64_t)sqlite3_last_insert_rowid(db->handle);
+}
+
+int SQLite3_changes(SQLite* db) {
+  return sqlite3_changes(db->handle);
+}
+
+char* SQLite3_error_and_close(SQLite db) {
+  const char* msg = sqlite3_errmsg(db.handle);
+  size_t len = strlen(msg);
+  char* copy = CARP_MALLOC(len + 1);
+  memcpy(copy, msg, len + 1);
+  sqlite3_close_v2(db.handle);
+  return copy;
 }

test/sqlite3.carp

@@ -6,7 +6,9 @@
 ; Helpers
 ; ---------------------------------------------------------------------------
 
-(defn open-memory [] (Result.unsafe-from-success (SQLite3.open ":memory:")))
+(defn open-memory []
+  (Result.expect (SQLite3.open ":memory:")
+                 "test setup failed: could not open :memory: db"))
 
 ; ---------------------------------------------------------------------------
 ; Tests
@@ -245,4 +247,122 @@
     &(str &(SQLite3.Type.Floating 1.5))
     "Type.Floating str")
 
-  (assert-equal test "(Null)" &(str &(SQLite3.Type.Null)) "Type.Null str"))
+  (assert-equal test "(Null)" &(str &(SQLite3.Type.Null)) "Type.Null str")
+
+  ; =========================================================================
+  ; last-insert-rowid
+  ; =========================================================================
+
+  (assert-equal test
+    1l
+    (let-do [db (open-memory)]
+      (ignore (SQLite3.query &db "CREATE TABLE t (id INTEGER PRIMARY KEY);" &[]))
+      (ignore (SQLite3.query &db "INSERT INTO t VALUES (NULL);" &[]))
+      (let-do [r (SQLite3.last-insert-rowid &db)] (SQLite3.close db) r))
+    "last-insert-rowid returns 1 after first insert")
+
+  (assert-equal test
+    2l
+    (let-do [db (open-memory)]
+      (ignore (SQLite3.query &db "CREATE TABLE t (id INTEGER PRIMARY KEY);" &[]))
+      (ignore (SQLite3.query &db "INSERT INTO t VALUES (NULL);" &[]))
+      (ignore (SQLite3.query &db "INSERT INTO t VALUES (NULL);" &[]))
+      (let-do [r (SQLite3.last-insert-rowid &db)] (SQLite3.close db) r))
+    "last-insert-rowid returns 2 after second insert")
+
+  ; =========================================================================
+  ; changes
+  ; =========================================================================
+
+  (assert-equal test
+    3
+    (let-do [db (open-memory)]
+      (ignore (SQLite3.query &db "CREATE TABLE t (x INT);" &[]))
+      (ignore (SQLite3.query &db "INSERT INTO t VALUES (1);" &[]))
+      (ignore (SQLite3.query &db "INSERT INTO t VALUES (2);" &[]))
+      (ignore (SQLite3.query &db "INSERT INTO t VALUES (3);" &[]))
+      (ignore (SQLite3.query &db "DELETE FROM t;" &[]))
+      (let-do [r (SQLite3.changes &db)] (SQLite3.close db) r))
+    "changes returns 3 after deleting 3 rows")
+
+  ; =========================================================================
+  ; Transactions - begin / commit
+  ; =========================================================================
+
+  (assert-true test
+    (let-do [db (open-memory)]
+      (let-do [r (SQLite3.begin &db)]
+        (ignore (SQLite3.commit &db))
+        (SQLite3.close db)
+        (Result.success? &r)))
+    "begin succeeds")
+
+  (assert-equal test
+    &(Result.Success [[(SQLite3.Type.Integer 1l)]])
+    &(let-do [db (open-memory)]
+      (ignore (SQLite3.query &db "CREATE TABLE t (x INT);" &[]))
+      (ignore (SQLite3.begin &db))
+      (ignore (SQLite3.query &db "INSERT INTO t VALUES (1);" &[]))
+      (ignore (SQLite3.commit &db))
+      (let-do [r (SQLite3.query &db "SELECT * FROM t;" &[])]
+        (SQLite3.close db)
+        r))
+    "committed data persists")
+
+  ; =========================================================================
+  ; Transactions - rollback
+  ; =========================================================================
+
+  (assert-equal test
+    &(Result.Success (the (Array (Array SQLite3.Type)) []))
+    &(let-do [db (open-memory)]
+      (ignore (SQLite3.query &db "CREATE TABLE t (x INT);" &[]))
+      (ignore (SQLite3.begin &db))
+      (ignore (SQLite3.query &db "INSERT INTO t VALUES (1);" &[]))
+      (ignore (SQLite3.rollback &db))
+      (let-do [r (SQLite3.query &db "SELECT * FROM t;" &[])]
+        (SQLite3.close db)
+        r))
+    "rolled-back data is gone")
+
+  ; =========================================================================
+  ; with-transaction macro - success path
+  ; =========================================================================
+
+  (assert-equal test
+    &(Result.Success [[(SQLite3.Type.Integer 1l)]])
+    &(let-do [db (open-memory)]
+      (ignore (SQLite3.query &db "CREATE TABLE t (x INT);" &[]))
+      (let-do [r (SQLite3.with-transaction &db
+                                           (do
+                                             (ignore
+                                               (SQLite3.query &db
+                                                              "INSERT INTO t VALUES (1);"
+                                                              &[]))
+                                             (SQLite3.query &db
+                                                            "SELECT * FROM t;"
+                                                            &[])))]
+        (SQLite3.close db)
+        r))
+    "with-transaction commits on success")
+
+  ; =========================================================================
+  ; with-transaction macro - error path (rollback)
+  ; =========================================================================
+
+  (assert-equal test
+    &(Result.Success (the (Array (Array SQLite3.Type)) []))
+    &(let-do [db (open-memory)]
+      (ignore (SQLite3.query &db "CREATE TABLE t (x INT);" &[]))
+      (ignore
+        (SQLite3.with-transaction &db
+                                  (do
+                                    (ignore
+                                      (SQLite3.query &db
+                                                     "INSERT INTO t VALUES (1);"
+                                                     &[]))
+                                    (SQLite3.query &db "NOT VALID SQL;" &[]))))
+      (let-do [r (SQLite3.query &db "SELECT * FROM t;" &[])]
+        (SQLite3.close db)
+        r))
+    "with-transaction rolls back on error"))