Added Python codec name to the connection.

This allows dropping repeated dictionary lookups with unicode
query/parameters.

Author: dvarrazzo

ChangeLog

@@ -1,3 +1,8 @@
+2010-12-18  Daniele Varrazzo  <daniele.varrazzo@gmail.com>
+
+	* connection.h: added codec attribute to avoid repeated codec name
+	lookups during unicode query/params manipulations.
+
 2010-12-15  Daniele Varrazzo  <daniele.varrazzo@gmail.com>
 
 	* psycopg/utils.c: Added psycopg_strdup function.

NEWS-2.3

@@ -4,6 +4,7 @@ What's new in psycopg 2.3.2
   - Improved PostgreSQL-Python encodings mapping. Added a few
     missing encodings: EUC_CN, EUC_JIS_2004, ISO885910, ISO885916,
     LATIN10, SHIFT_JIS_2004.
+  - Dropped repeated dictionary lookups with unicode query/parameters.
 
 
 What's new in psycopg 2.3.1

psycopg/adapter_qstring.c

@@ -49,22 +49,9 @@ qstring_quote(qstringObject *self)
     Dprintf("qstring_quote: encoding to %s", self->encoding);
 
     if (PyUnicode_Check(self->wrapped) && self->encoding) {
-        PyObject *enc = PyDict_GetItemString(psycoEncodings, self->encoding);
-        /* note that enc is a borrowed reference */
-
-        if (enc) {
-            const char *s = PyString_AsString(enc);
-            Dprintf("qstring_quote: encoding unicode object to %s", s);
-            str = PyUnicode_AsEncodedString(self->wrapped, s, NULL);
-            Dprintf("qstring_quote: got encoded object at %p", str);
-            if (str == NULL) return NULL;
-        }
-        else {
-            /* can't find the right encoder, raise exception */
-            PyErr_Format(InterfaceError,
-                         "can't encode unicode string to %s", self->encoding);
-            return NULL;
-        }
+        str = PyUnicode_AsEncodedString(self->wrapped, self->encoding, NULL);
+        Dprintf("qstring_quote: got encoded object at %p", str);
+        if (str == NULL) return NULL;
     }
 
     /* if the wrapped object is a simple string, we don't know how to
@@ -144,8 +131,8 @@ qstring_prepare(qstringObject *self, PyObject *args)
        we don't need the encoding if that's not the case */
     if (PyUnicode_Check(self->wrapped)) {
         if (self->encoding) free(self->encoding);
-        self->encoding = strdup(conn->encoding);
-        Dprintf("qstring_prepare: set encoding to %s", conn->encoding);
+        self->encoding = strdup(conn->codec);
+        Dprintf("qstring_prepare: set encoding to %s", conn->codec);
     }
 
     Py_CLEAR(self->conn);

psycopg/adapter_qstring.h

@@ -37,6 +37,10 @@ typedef struct {
 
     PyObject *wrapped;
     PyObject *buffer;
+    /* NOTE: this used to be a PostgreSQL encoding: changed in 2.3.2 to be a
+     * Python codec name. I don't expect there has been any user for this
+     * object other than adapting str/unicode, so I don't expect client code
+     * broken for this reason. */
     char     *encoding;
 
     PyObject *conn;

psycopg/connection.h

@@ -83,6 +83,7 @@ typedef struct {
     char *dsn;              /* data source name */
     char *critical;         /* critical error on this connection */
     char *encoding;         /* current backend encoding */
+    char *codec;            /* python codec name for encoding */
 
     long int closed;          /* 1 means connection has been closed;
                                  2 that something horrible happened */

psycopg/connection_int.c

@@ -212,38 +212,89 @@ conn_get_standard_conforming_strings(PGconn *pgconn)
     return equote;
 }
 
-/* Return a string containing the client_encoding setting.
+/* Convert a PostgreSQL encoding to a Python codec.
  *
- * Return a new string allocated by malloc(): use free() to free it.
- * Return NULL in case of failure.
+ * Return a new copy of the codec name allocated on the Python heap,
+ * NULL with exception in case of error.
  */
 static char *
-conn_get_encoding(PGconn *pgconn)
+conn_encoding_to_codec(const char *enc)
 {
-    const char *tmp, *i;
-    char *encoding, *j;
+    char *tmp;
+    Py_ssize_t size;
+    PyObject *pyenc;
+    char *rv = NULL;
+
+    if (!(pyenc = PyDict_GetItemString(psycoEncodings, enc))) {
+        PyErr_Format(OperationalError,
+            "no Python codec for client encoding '%s'", enc);
+        goto exit;
+    }
+    if (-1 == PyString_AsStringAndSize(pyenc, &tmp, &size)) {
+        goto exit;
+    }
+
+    /* have our own copy of the python codec name */
+    rv = psycopg_strdup(tmp, size);
+
+exit:
+    /* pyenc is borrowed: no decref. */
+    return rv;
+}
+
+/* Read the client encoding from the connection.
+ *
+ * Store the encoding in the pgconn->encoding field and the name of the
+ * matching python codec in codec. The buffers are allocated on the Python
+ * heap.
+ *
+ * Return 0 on success, else nonzero.
+ */
+static int
+conn_read_encoding(connectionObject *self, PGconn *pgconn)
+{
+    char *enc = NULL, *codec = NULL, *j;
+    const char *tmp;
+    int rv = -1;
 
     tmp = PQparameterStatus(pgconn, "client_encoding");
     Dprintf("conn_connect: client encoding: %s", tmp ? tmp : "(none)");
     if (!tmp) {
         PyErr_SetString(OperationalError,
             "server didn't return client encoding");
-        return NULL;
+        goto exit;
     }
 
-    encoding = malloc(strlen(tmp)+1);
-    if (encoding == NULL) {
+    if (!(enc = PyMem_Malloc(strlen(tmp)+1))) {
         PyErr_NoMemory();
-        return NULL;
+        goto exit;
     }
 
-    /* return in uppercase */
-    i = tmp;
-    j = encoding;
-    while (*i) { *j++ = toupper(*i++); }
+    /* turn encoding in uppercase */
+    j = enc;
+    while (*tmp) { *j++ = toupper(*tmp++); }
     *j = '\0';
 
-    return encoding;
+    /* Look for this encoding in Python codecs. */
+    if (!(codec = conn_encoding_to_codec(enc))) {
+        goto exit;
+    }
+
+    /* Good, success: store the encoding/codec in the connection. */
+    PyMem_Free(self->encoding);
+    self->encoding = enc;
+    enc = NULL;
+
+    PyMem_Free(self->codec);
+    self->codec = codec;
+    codec = NULL;
+
+    rv = 0;
+
+exit:
+    PyMem_Free(enc);
+    PyMem_Free(codec);
+    return rv;
 }
 
 int
@@ -319,9 +370,8 @@ conn_setup(connectionObject *self, PGconn *pgconn)
         PyErr_SetString(InterfaceError, "only protocol 3 supported");
         return -1;
     }
-    /* conn_get_encoding returns a malloc'd string */
-    self->encoding = conn_get_encoding(pgconn);
-    if (self->encoding == NULL) {
+
+    if (conn_read_encoding(self, pgconn)) {
         return -1;
     }
 
@@ -651,9 +701,7 @@ _conn_poll_setup_async(connectionObject *self)
             PyErr_SetString(InterfaceError, "only protocol 3 supported");
             break;
         }
-        /* conn_get_encoding returns a malloc'd string */
-        self->encoding = conn_get_encoding(self->pgconn);
-        if (self->encoding == NULL) {
+        if (conn_read_encoding(self, self->pgconn)) {
             break;
         }
         self->cancel = conn_get_cancel(self->pgconn);
@@ -873,11 +921,15 @@ conn_set_client_encoding(connectionObject *self, const char *enc)
     char *error = NULL;
     char query[48];
     int res = 0;
+    char *codec;
 
     /* If the current encoding is equal to the requested one we don't
        issue any query to the backend */
     if (strcmp(self->encoding, enc) == 0) return 0;
 
+    /* We must know what python codec this encoding is. */
+    if (!(codec = conn_encoding_to_codec(enc))) { return -1; }
+
     Py_BEGIN_ALLOW_THREADS;
     pthread_mutex_lock(&self->lock);
 
@@ -886,19 +938,29 @@ conn_set_client_encoding(connectionObject *self, const char *enc)
 
     /* abort the current transaction, to set the encoding ouside of
        transactions */
-    res = pq_abort_locked(self, &pgres, &error, &_save);
-
-    if (res == 0) {
-        res = pq_execute_command_locked(self, query, &pgres, &error, &_save);
-        if (res == 0) {
-            /* no error, we can proceeed and store the new encoding */
-            if (self->encoding) free(self->encoding);
-            self->encoding = strdup(enc);
-            Dprintf("conn_set_client_encoding: set encoding to %s",
-                    self->encoding);
-        }
+    if ((res = pq_abort_locked(self, &pgres, &error, &_save))) {
+        goto endlock;
+    }
+
+    if ((res = pq_execute_command_locked(self, query, &pgres, &error, &_save))) {
+        goto endlock;
     }
 
+    /* no error, we can proceeed and store the new encoding */
+    PyMem_Free(self->encoding);
+    if (!(self->encoding = psycopg_strdup(enc, 0))) {
+        res = 1;  /* don't call pq_complete_error below */
+        goto endlock;
+    }
+
+    /* Store the python codec too. */
+    PyMem_Free(self->codec);
+    self->codec = codec;
+
+    Dprintf("conn_set_client_encoding: set encoding to %s (codec: %s)",
+            self->encoding, self->codec);
+
+endlock:
 
     pthread_mutex_unlock(&self->lock);
     Py_END_ALLOW_THREADS;

psycopg/connection_type.c

@@ -425,35 +425,38 @@ psyco_conn_set_isolation_level(connectionObject *self, PyObject *args)
 static PyObject *
 psyco_conn_set_client_encoding(connectionObject *self, PyObject *args)
 {
-    const char *enc = NULL;
-    char *buffer;
-    size_t i, j;
+    const char *enc;
+    char *buffer, *dest;
+    PyObject *rv = NULL;
+    Py_ssize_t len;
 
     EXC_IF_CONN_CLOSED(self);
     EXC_IF_CONN_ASYNC(self, set_client_encoding);
     EXC_IF_TPC_PREPARED(self, set_client_encoding);
 
-    if (!PyArg_ParseTuple(args, "s", &enc)) return NULL;
+    if (!PyArg_ParseTuple(args, "s#", &enc, &len)) return NULL;
 
     /* convert to upper case and remove '-' and '_' from string */
-    buffer = PyMem_Malloc(strlen(enc)+1);
-    for (i=j=0 ; i < strlen(enc) ; i++) {
-        if (enc[i] == '_' || enc[i] == '-')
-            continue;
-        else
-            buffer[j++] = toupper(enc[i]);
+    if (!(dest = buffer = PyMem_Malloc(len+1))) {
+        return PyErr_NoMemory();
+    }
+
+    while (*enc) {
+        if (*enc == '_' || *enc == '-') {
+            ++enc;
+        }
+        else {
+            *dest++ = toupper(*enc++);
+        }
     }
-    buffer[j] = '\0';
+    *dest = '\0';
 
     if (conn_set_client_encoding(self, buffer) == 0) {
-        PyMem_Free(buffer);
         Py_INCREF(Py_None);
-        return Py_None;
-    }
-    else {
-        PyMem_Free(buffer);
-        return NULL;
+        rv = Py_None;
     }
+    PyMem_Free(buffer);
+    return rv;
 }
 
 /* get_transaction_status method - Get backend transaction status */
@@ -892,7 +895,8 @@ connection_dealloc(PyObject* obj)
     conn_notice_clean(self);
 
     if (self->dsn) free(self->dsn);
-    if (self->encoding) free(self->encoding);
+    PyMem_Free(self->encoding);
+    PyMem_Free(self->codec);
     if (self->critical) free(self->critical);
 
     Py_CLEAR(self->async_cursor);

psycopg/cursor_type.c

@@ -272,21 +272,11 @@ static PyObject *_psyco_curs_validate_sql_basic(
         Py_INCREF(sql);
     }
     else if (PyUnicode_Check(sql)) {
-        PyObject *enc = PyDict_GetItemString(psycoEncodings,
-                                             self->conn->encoding);
-        /* enc is a borrowed reference; we won't decref it */
-
-        if (enc) {
-            sql = PyUnicode_AsEncodedString(sql, PyString_AsString(enc), NULL);
-            /* if there was an error during the encoding from unicode to the
-               target encoding, we just let the exception propagate */
-            if (sql == NULL) { goto fail; }
-        } else {
-            PyErr_Format(InterfaceError,
-                         "can't encode unicode SQL statement to %s",
-                         self->conn->encoding);
-            goto fail;
-        }
+        char *enc = self->conn->codec;
+        sql = PyUnicode_AsEncodedString(sql, enc, NULL);
+        /* if there was an error during the encoding from unicode to the
+           target encoding, we just let the exception propagate */
+        if (sql == NULL) { goto fail; }
     }
     else {
         /* the  is not unicode or string, raise an error */

psycopg/typecast_basic.c

@@ -82,21 +82,12 @@ typecast_STRING_cast(const char *s, Py_ssize_t len, PyObject *curs)
 static PyObject *
 typecast_UNICODE_cast(const char *s, Py_ssize_t len, PyObject *curs)
 {
-    PyObject *enc;
+    char *enc;
 
     if (s == NULL) {Py_INCREF(Py_None); return Py_None;}
 
-    enc = PyDict_GetItemString(psycoEncodings,
-                               ((cursorObject*)curs)->conn->encoding);
-    if (enc) {
-        return PyUnicode_Decode(s, len, PyString_AsString(enc), NULL);
-    }
-    else {
-       PyErr_Format(InterfaceError,
-                    "can't decode into unicode string from %s",
-                    ((cursorObject*)curs)->conn->encoding);
-       return NULL;
-    }
+    enc = ((cursorObject*)curs)->conn->codec;
+    return PyUnicode_Decode(s, len, enc, NULL);
 }
 
 /** BOOLEAN - cast boolean value into right python object **/