From b6d6fbbe8ccfd38fb9d0fab876802def9255930b Mon Sep 17 00:00:00 2001
From: Daniele Varrazzo <daniele.varrazzo@gmail.com>
Date: Thu, 17 Feb 2011 20:08:04 +0000
Subject: [PATCH] Use a global object for NULL

Small optimization as NULL is a frequent value to build.
---
 psycopg/adapter_asis.c  |  3 ++-
 psycopg/adapter_list.c  | 11 +++++++----
 psycopg/cursor_type.c   |  8 +++++---
 psycopg/psycopg.h       |  3 +++
 psycopg/psycopgmodule.c |  4 ++++
 5 files changed, 21 insertions(+), 8 deletions(-)

diff --git a/psycopg/adapter_asis.c b/psycopg/adapter_asis.c
index bc64aa74..f194e1d1 100644
--- a/psycopg/adapter_asis.c
+++ b/psycopg/adapter_asis.c
@@ -39,7 +39,8 @@ asis_getquoted(asisObject *self, PyObject *args)
 {
     PyObject *rv;
     if (self->wrapped == Py_None) {
-        rv = Bytes_FromString("NULL");
+        Py_INCREF(psyco_null);
+        rv = psyco_null;
     }
     else {
         rv = PyObject_Str(self->wrapped);
diff --git a/psycopg/adapter_list.c b/psycopg/adapter_list.c
index d5c5b4a3..cbb75422 100644
--- a/psycopg/adapter_list.c
+++ b/psycopg/adapter_list.c
@@ -52,12 +52,15 @@ list_quote(listObject *self)
     for (i=0; i<len; i++) {
         PyObject *quoted;
         PyObject *wrapped = PyList_GET_ITEM(self->wrapped, i);
-        if (wrapped == Py_None)
-            quoted = Bytes_FromString("NULL");
-        else
+        if (wrapped == Py_None) {
+            Py_INCREF(psyco_null);
+            quoted = psyco_null;
+        }
+        else {
             quoted = microprotocol_getquoted(wrapped,
                                        (connectionObject*)self->connection);
-        if (quoted == NULL) goto error;
+            if (quoted == NULL) goto error;
+        }
 
         /* here we don't loose a refcnt: SET_ITEM does not change the
            reference count and we are just transferring ownership of the tmp
diff --git a/psycopg/cursor_type.c b/psycopg/cursor_type.c
index 4330d77f..159b9de8 100644
--- a/psycopg/cursor_type.c
+++ b/psycopg/cursor_type.c
@@ -142,9 +142,10 @@ _mogrify(PyObject *var, PyObject *fmt, connectionObject *conn, PyObject **new)
 
                     /* None is always converted to NULL; this is an
                        optimization over the adapting code and can go away in
-                       the future if somebody finds a None adapter usefull. */
+                       the future if somebody finds a None adapter useful. */
                     if (value == Py_None) {
-                        t = Bytes_FromString("NULL");
+                        Py_INCREF(psyco_null);
+                        t = psyco_null;
                         PyDict_SetItem(n, key, t);
                         /* t is a new object, refcnt = 1, key is at 2 */
 
@@ -220,7 +221,8 @@ _mogrify(PyObject *var, PyObject *fmt, connectionObject *conn, PyObject **new)
             d = c+1;
 
             if (value == Py_None) {
-                PyTuple_SET_ITEM(n, index, Bytes_FromString("NULL"));
+                Py_INCREF(psyco_null);
+                PyTuple_SET_ITEM(n, index, psyco_null);
                 while (*d && !isalpha(*d)) d++;
                 if (*d) *d = 's';
                 Py_DECREF(value);
diff --git a/psycopg/psycopg.h b/psycopg/psycopg.h
index 8edc42ed..710a51bc 100644
--- a/psycopg/psycopg.h
+++ b/psycopg/psycopg.h
@@ -105,6 +105,9 @@ import_psycopg(void)
 /* postgresql<->python encoding map */
 extern HIDDEN PyObject *psycoEncodings;
 
+/* SQL NULL */
+extern HIDDEN PyObject *psyco_null;
+
 typedef struct {
     char *pgenc;
     char *pyenc;
diff --git a/psycopg/psycopgmodule.c b/psycopg/psycopgmodule.c
index 7b6a3346..59562e25 100644
--- a/psycopg/psycopgmodule.c
+++ b/psycopg/psycopgmodule.c
@@ -66,6 +66,9 @@ HIDDEN PyObject *psycoEncodings = NULL;
 HIDDEN int psycopg_debug_enabled = 0;
 #endif
 
+/* Python representation of SQL NULL */
+HIDDEN PyObject *psyco_null = NULL;
+
 /** connect module-level function **/
 #define psyco_connect_doc \
 "connect(dsn, ...) -- Create a new database connection.\n\n"               \
@@ -882,6 +885,7 @@ INIT_MODULE(_psycopg)(void)
     /* other mixed initializations of module-level variables */
     psycoEncodings = PyDict_New();
     psyco_encodings_fill(psycoEncodings);
+    psyco_null = Bytes_FromString("NULL");
 
     /* set some module's parameters */
     PyModule_AddStringConstant(module, "__version__", PSYCOPG_VERSION);