From 920c4451883e3919930235a1d7fc8c05b80c281c Mon Sep 17 00:00:00 2001
From: Arjun Khandkar <khandkar.arjun@heb.com>
Date: Thu, 16 Oct 2025 19:06:17 +0530
Subject: [PATCH] Close statements after use

---
 src/Database/Oracle/Simple/Execute.hs  | 10 ++++++++--
 src/Database/Oracle/Simple/Internal.hs | 15 +++++++++++++--
 src/Database/Oracle/Simple/Query.hs    | 13 ++++++++++---
 3 files changed, 31 insertions(+), 7 deletions(-)

diff --git a/src/Database/Oracle/Simple/Execute.hs b/src/Database/Oracle/Simple/Execute.hs
index fd784a2..78b2ffd 100644
--- a/src/Database/Oracle/Simple/Execute.hs
+++ b/src/Database/Oracle/Simple/Execute.hs
@@ -16,6 +16,7 @@ import Database.Oracle.Simple.Internal
     Connection,
     DPIModeExec (DPI_MODE_EXEC_DEFAULT),
     dpiExecute,
+    closeStatement,
     getRowCount,
     prepareStmt,
   )
@@ -29,14 +30,18 @@ execute conn sql param = do
   stmt <- prepareStmt conn sql
   _ <- evalStateT (runRowWriter (toRow param) stmt) (Column 0)
   _ <- dpiExecute stmt DPI_MODE_EXEC_DEFAULT
-  getRowCount stmt
+  rowCount <- getRowCount stmt
+  closeStatement stmt
+  pure rowCount
 
 -- | A version of 'execute' that does not perform query substitution.
 execute_ :: Connection -> String -> IO Word64
 execute_ conn sql = do
   stmt <- prepareStmt conn sql
   _ <- dpiExecute stmt DPI_MODE_EXEC_DEFAULT
-  getRowCount stmt
+  rowCount <- getRowCount stmt
+  closeStatement stmt
+  pure rowCount
 
 {- | Execute a multi-row INSERT, UPDATE or other SQL query that is not expected to return results.
 Returns the number of rows affected. If the list of parameters is empty, the function will simply
@@ -52,4 +57,5 @@ executeMany conn sql params = do
       _ <- evalStateT (runRowWriter (toRow param) stmt) (Column 0)
       _ <- dpiExecute stmt DPI_MODE_EXEC_DEFAULT
       rowsAffected <- getRowCount stmt
+      closeStatement stmt
       pure (totalRowsAffected + rowsAffected)
diff --git a/src/Database/Oracle/Simple/Internal.hs b/src/Database/Oracle/Simple/Internal.hs
index 44a7589..1404e63 100644
--- a/src/Database/Oracle/Simple/Internal.hs
+++ b/src/Database/Oracle/Simple/Internal.hs
@@ -49,6 +49,7 @@ module Database.Oracle.Simple.Internal
     ping,
     fetch,
     close,
+    closeStatement,
     connect,
     withConnection,
     withConnCreateParams,
@@ -1908,6 +1909,18 @@ foreign import ccall unsafe "dpiConn_getIsHealthy"
     Ptr CInt ->
     IO CInt
 
+foreign import ccall "dpiStmt_close"
+  dpiStmt_close ::
+    DPIStmt ->
+    CString ->
+    CUInt ->
+    IO CInt
+
+-- | Close the statement and make it unusable for further work immediately.
+closeStatement :: DPIStmt -> IO ()
+closeStatement stmt =
+  throwOracleError =<< dpiStmt_close stmt nullPtr 0
+
 -- | A pointer to an integer defining whether the connection is healthy (1) or not (0), which will be populated upon successful completion of this function.
 isHealthy :: Connection -> IO Bool
 isHealthy (Connection fptr) =
@@ -1922,5 +1935,3 @@ Structurally equivalent to 'Data.Functor.Identity.Identity'.
 newtype Only a = Only {fromOnly :: a}
   deriving stock (Eq, Ord, Read, Show, Generic)
   deriving newtype (Enum)
-
-
diff --git a/src/Database/Oracle/Simple/Query.hs b/src/Database/Oracle/Simple/Query.hs
index 04f40d5..177aa86 100644
--- a/src/Database/Oracle/Simple/Query.hs
+++ b/src/Database/Oracle/Simple/Query.hs
@@ -13,6 +13,7 @@ import Database.Oracle.Simple.Internal
     Connection,
     DPIModeExec (DPI_MODE_EXEC_DEFAULT),
     dpiExecute,
+    closeStatement,
     fetch,
     prepareStmt,
   )
@@ -29,7 +30,9 @@ query conn sql param = do
   found <- fetch stmt
   loop stmt found
   where
-    loop _ n | n < 1 = pure []
+    loop _ n | n < 1 = do
+      closeStatement stmt
+      pure []
     loop stmt _ = do
       tsVal <- getRow stmt
       found <- fetch stmt
@@ -43,7 +46,9 @@ query_ conn sql = do
   found <- fetch stmt
   loop stmt found
   where
-    loop _ n | n < 1 = pure []
+    loop _ n | n < 1 = do
+      closeStatement stmt
+      pure []
     loop stmt _ = do
       tsVal <- getRow stmt
       found <- fetch stmt
@@ -57,7 +62,9 @@ forEach_ conn sql cont = do
   found <- fetch stmt
   loop stmt found
   where
-    loop _ n | n < 1 = pure ()
+    loop _ n | n < 1 = do
+      closeStatement stmt
+      pure ()
     loop stmt _ = do
       tsVal <- getRow stmt
       cont tsVal