From c3a4cb2796c18b9bc89af0789c167a9d237dcea5 Mon Sep 17 00:00:00 2001
From: Kovid Goyal <kovid@kovidgoyal.net>
Date: Tue, 17 Sep 2024 10:19:59 +0530
Subject: [PATCH] A faster deepcopy that specializes to C code for builtin
 types

---
 src/calibre/utils/speedup.c | 125 +++++++++++++++++++++++++++++++++++-
 1 file changed, 123 insertions(+), 2 deletions(-)

diff --git a/src/calibre/utils/speedup.c b/src/calibre/utils/speedup.c
index fc3a209f6e..f89f4cb9b6 100644
--- a/src/calibre/utils/speedup.c
+++ b/src/calibre/utils/speedup.c
@@ -520,8 +520,9 @@ get_element_char_length(PyObject *self, PyObject *args) {
 	int is_ignored_tag = 0;
 	size_t ans = 0;
 #define EQ(x) memcmp(ltagname, #x, sizeof(#x) - 1) == 0
-	if (EQ(script) || EQ(noscript) || EQ(style) || EQ(title)) is_ignored_tag = 1;
-	if (EQ(img) || EQ(svg)) ans += 1000;
+	if (EQ(script) || EQ(noscript) || EQ(style) || EQ(title)) {
+        is_ignored_tag = 1;
+    } else if (EQ(img) || EQ(svg)) ans += 1000;
 #undef EQ
 	if (tail != Py_None) ans += count_chars_in(tail);
 	if (text != Py_None && !is_ignored_tag) ans += count_chars_in(text);
@@ -529,7 +530,127 @@ get_element_char_length(PyObject *self, PyObject *args) {
 }
 
 
+typedef struct deepcopy_data {
+    PyObject *python_deepcopy, *memo;
+} deepcopy_data;
+
+static PyObject* deepcopy_object(PyObject *, deepcopy_data *);
+
+static PyObject*
+insert_into_cache(PyObject *o, deepcopy_data *d) {
+    if (!o) return NULL;
+    PyObject *key = PyLong_FromVoidPtr(o);
+    if (!key) { Py_DECREF(o); return NULL; }
+    if (PyDict_SetItem(d->memo, key, o) != 0) { Py_DECREF(key); Py_DECREF(o); return NULL; }
+    return o;
+}
+
+static PyObject*
+deepcopy_list(PyObject *o, deepcopy_data *d) {
+    PyObject *ans = insert_into_cache(PyList_New(PyList_GET_SIZE(o)), d);
+    if (!ans) return NULL;
+    for (Py_ssize_t i = 0; i < PyList_GET_SIZE(o); i++) {
+        PyObject *t = deepcopy_object(PyList_GET_ITEM(o, i), d);
+        if (!t) { Py_CLEAR(t); return NULL; }
+        PyList_SET_ITEM(ans, i, t);
+    }
+    return ans;
+}
+
+static PyObject*
+deepcopy_tuple(PyObject *o, deepcopy_data *d) {
+    PyObject *ans = insert_into_cache(PyTuple_New(PyTuple_GET_SIZE(o)), d);
+    if (!ans) return NULL;
+    for (Py_ssize_t i = 0; i < PyTuple_GET_SIZE(o); i++) {
+        PyObject *t = deepcopy_object(PyTuple_GET_ITEM(o, i), d);
+        if (!t) { Py_CLEAR(ans); return NULL; }
+        PyTuple_SET_ITEM(ans, i, t);
+    }
+    return ans;
+}
+
+
+static PyObject*
+deepcopy_dict(PyObject *o, deepcopy_data *d) {
+    PyObject *key, *value;
+    Py_ssize_t pos = 0;
+    PyObject *ans = insert_into_cache(PyDict_New(), d);
+    if (!ans) return NULL;
+
+    while (PyDict_Next(o, &pos, &key, &value)) {
+        PyObject *tk = deepcopy_object(key, d);
+        if (!tk) break;
+        PyObject *tv = deepcopy_object(value, d);
+        if (!tv) { Py_DECREF(tk); break; }
+        int ok = PyDict_SetItem(ans, tk, tv) == 0;
+        Py_DECREF(tk); Py_DECREF(tv);
+        if (!ok) break;
+    }
+    if (PyErr_Occurred()) { Py_DECREF(ans); return NULL; }
+    return ans;
+}
+
+static PyObject*
+deepcopy_set(PyObject *o, deepcopy_data *d, int is_frozen) {
+    PyObject *ans = insert_into_cache(is_frozen ? PyFrozenSet_New(NULL) : PySet_New(NULL), d);
+    if (!ans) return NULL;
+    PyObject *iter = PyObject_GetIter(o);
+    if (!iter) { Py_DECREF(ans); return NULL; }
+    PyObject *key;
+    while ((key = PyIter_Next(iter)) != NULL) {
+        PyObject *t = deepcopy_object(key, d);
+        if (!t) break;
+        if (PySet_Add(ans, t) != 0) { Py_DECREF(t); break; }
+    }
+    Py_DECREF(iter);
+    if (PyErr_Occurred()) { Py_DECREF(ans); return NULL; }
+    return ans;
+}
+
+static PyObject*
+deepcopy_object(PyObject *o, deepcopy_data *d) {
+    PyObject *key = PyLong_FromVoidPtr(o);
+    if (!key) return NULL;
+    PyObject *cached = PyDict_GetItem(d->memo, key);
+    Py_DECREF(key);
+    if (cached) return Py_NewRef(cached);
+    PyTypeObject *type;
+    // Fast case for builtin immutable types
+    if (
+        o == Py_None || o == Py_True || o == Py_False || (type = Py_TYPE(o)) == &PyUnicode_Type ||
+        type == &PyBytes_Type || type == &PyLong_Type || type == &PyFloat_Type || type == &PyMemoryView_Type ||
+        type == &PyComplex_Type || type == &PyType_Type || type == &PyFunction_Type || type == &PyCode_Type ||
+        o == Py_Ellipsis || o == Py_NotImplemented
+    ) return Py_NewRef(o);
+    if (type == &PyList_Type) return deepcopy_list(o, d);
+    if (type == &PyTuple_Type) return deepcopy_tuple(o, d);
+    if (type == &PyDict_Type) return deepcopy_dict(o, d);
+    if (type == &PySet_Type) return deepcopy_set(o, d, 0);
+    if (type == &PyFrozenSet_Type) return deepcopy_set(o, d, 1);
+    if (PyWeakref_Check(o)) return Py_NewRef(o);
+    return PyObject_CallFunctionObjArgs(d->python_deepcopy, o, d->memo);
+}
+
+static PyObject*
+deepcopy(PyObject *self, PyObject *o) {
+    PyObject *memo = PyDict_New();
+    if (!memo) return NULL;
+    PyObject *copy_module = PyImport_ImportModule("copy");
+    if (!copy_module) { Py_DECREF(memo); return NULL; }
+    PyObject *python_deepcopy = PyObject_GetAttrString(copy_module, "deepcopy");
+    Py_DECREF(copy_module);
+    if (!python_deepcopy) { Py_DECREF(memo); return NULL; }
+    deepcopy_data d = {.python_deepcopy = python_deepcopy, .memo = memo};
+    PyObject *ans = deepcopy_object(o, &d);
+    Py_DECREF(python_deepcopy); Py_DECREF(memo);
+    return ans;
+}
+
 static PyMethodDef speedup_methods[] = {
+    {"deepcopy", deepcopy, METH_O,
+        "deepcopy(object)\n\nFast implementation of deepcopy()"
+    },
+
     {"parse_date", speedup_parse_date, METH_VARARGS,
         "parse_date()\n\nParse ISO dates faster (specialized for dates stored in the calibre db)."
     },