cpython/Modules/_sqlite/cache.c at master · python-emscripten/cpython · GitHub

Repository navigation

History

100

101

102

103

104

105

106

107

108

109

110

111

112

113

114

115

116

117

118

119

120

121

122

123

124

125

126

127

128

129

130

131

132

133

134

135

136

137

138

139

140

141

142

143

144

145

146

147

148

149

150

151

152

153

154

155

156

157

158

159

160

161

162

163

164

165

166

167

168

169

170

171

172

173

174

175

176

177

178

179

180

181

182

183

184

185

186

187

188

189

190

191

192

193

194

195

196

197

198

199

200

201

202

203

204

205

206

207

208

209

210

211

212

213

214

215

216

217

218

219

220

221

222

223

224

225

226

227

228

229

230

231

232

233

234

235

236

237

238

239

240

241

242

243

244

245

246

247

248

249

250

251

252

253

254

255

256

257

258

259

260

261

262

263

264

265

266

267

268

269

270

271

272

273

274

275

276

277

278

279

280

281

282

283

284

285

286

287

288

289

290

291

292

293

294

295

296

297

298

299

300

301

302

303

304

305

306

307

308

309

310

311

312

313

314

315

316

317

318

319

320

321

322

323

324

325

326

327

328

329

330

331

332

333

334

335

336

337

338

339

340

341

342

343

344

345

346

347

348

349

350

351

352

353

354

355

356

357

358

359

360

361

362

/* cache .c - a LRU cache

* This file is part of pysqlite.

* This software is provided 'as-is', without any express or implied

* warranty. In no event will the authors be held liable for any damages

* arising from the use of this software.

* Permission is granted to anyone to use this software for any purpose,

* including commercial applications, and to alter it and redistribute it

* freely, subject to the following restrictions:

* 1. The origin of this software must not be misrepresented; you must not

* claim that you wrote the original software. If you use this software

* in a product, an acknowledgment in the product documentation would be

* appreciated but is not required.

* 2. Altered source versions must be plainly marked as such, and must not be

* misrepresented as being the original software.

* 3. This notice may not be removed or altered from any source distribution.

#include "cache.h"

#include <limits.h>

/* only used internally */

pysqlite_Node* pysqlite_new_node(PyObject* key, PyObject* data)

{

pysqlite_Node* node;

node = (pysqlite_Node*) (pysqlite_NodeType.tp_alloc(&pysqlite_NodeType, 0));

if (!node) {

return NULL;

}

Py_INCREF(key);

node->key = key;

Py_INCREF(data);

node->data = data;

node->prev = NULL;

node->next = NULL;

return node;

}

void pysqlite_node_dealloc(pysqlite_Node* self)

{

Py_DECREF(self->key);

Py_DECREF(self->data);

Py_TYPE(self)->tp_free((PyObject*)self);

}

int pysqlite_cache_init(pysqlite_Cache* self, PyObject* args, PyObject* kwargs)

{

PyObject* factory;

int size = 10;

self->factory = NULL;

if (!PyArg_ParseTuple(args, "O|i", &factory, &size)) {

return -1;

}

/* minimum cache size is 5 entries */

if (size < 5) {

size = 5;

}

self->size = size;

self->first = NULL;

self->last = NULL;

self->mapping = PyDict_New();

if (!self->mapping) {

return -1;

}

Py_INCREF(factory);

self->factory = factory;

self->decref_factory = 1;

return 0;

}

void pysqlite_cache_dealloc(pysqlite_Cache* self)

{

pysqlite_Node* node;

pysqlite_Node* delete_node;

if (!self->factory) {

/* constructor failed, just get out of here */

return;

}

/* iterate over all nodes and deallocate them */

node = self->first;

while (node) {

delete_node = node;

node = node->next;

Py_DECREF(delete_node);

}

if (self->decref_factory) {

Py_DECREF(self->factory);

}

Py_DECREF(self->mapping);

Py_TYPE(self)->tp_free((PyObject*)self);

}

PyObject* pysqlite_cache_get(pysqlite_Cache* self, PyObject* key)

{

pysqlite_Node* node;

pysqlite_Node* ptr;

PyObject* data;

node = (pysqlite_Node*)PyDict_GetItemWithError(self->mapping, key);

if (node) {

/* an entry for this key already exists in the cache */

/* increase usage counter of the node found */

if (node->count < LONG_MAX) {

node->count++;

}

/* if necessary, reorder entries in the cache by swapping positions */

if (node->prev && node->count > node->prev->count) {

ptr = node->prev;

while (ptr->prev && node->count > ptr->prev->count) {

ptr = ptr->prev;

}

if (node->next) {

node->next->prev = node->prev;

} else {

self->last = node->prev;

}

if (node->prev) {

node->prev->next = node->next;

}

if (ptr->prev) {

ptr->prev->next = node;

} else {

self->first = node;

}

node->next = ptr;

node->prev = ptr->prev;

if (!node->prev) {

self->first = node;

}

ptr->prev = node;

}

else if (PyErr_Occurred()) {

return NULL;

}

else {

/* There is no entry for this key in the cache, yet. We'll insert a new

* entry in the cache, and make space if necessary by throwing the

* least used item out of the cache. */

if (PyDict_GET_SIZE(self->mapping) == self->size) {

if (self->last) {

node = self->last;

if (PyDict_DelItem(self->mapping, self->last->key) != 0) {

return NULL;

}

if (node->prev) {

node->prev->next = NULL;

}

self->last = node->prev;

node->prev = NULL;

Py_DECREF(node);

}

/* We cannot replace this by PyObject_CallOneArg() since

* PyObject_CallFunction() has a special case when using a

* single tuple as argument. */

data = PyObject_CallFunction(self->factory, "O", key);

if (!data) {

return NULL;

}

node = pysqlite_new_node(key, data);

if (!node) {

return NULL;

}

node->prev = self->last;

Py_DECREF(data);

if (PyDict_SetItem(self->mapping, key, (PyObject*)node) != 0) {

Py_DECREF(node);

return NULL;

}

if (self->last) {

self->last->next = node;

} else {

self->first = node;

}

self->last = node;

}

Py_INCREF(node->data);

return node->data;

}

PyObject* pysqlite_cache_display(pysqlite_Cache* self, PyObject* args)

{

pysqlite_Node* ptr;

PyObject* prevkey;

PyObject* nextkey;

PyObject* display_str;

ptr = self->first;

while (ptr) {

if (ptr->prev) {

prevkey = ptr->prev->key;

} else {

prevkey = Py_None;

}

if (ptr->next) {

nextkey = ptr->next->key;

} else {

nextkey = Py_None;

}

display_str = PyUnicode_FromFormat("%S <- %S -> %S\n",

prevkey, ptr->key, nextkey);

if (!display_str) {

return NULL;

}

PyObject_Print(display_str, stdout, Py_PRINT_RAW);

Py_DECREF(display_str);

ptr = ptr->next;

}

Py_RETURN_NONE;

}

static PyMethodDef cache_methods[] = {

{"get", (PyCFunction)pysqlite_cache_get, METH_O,

PyDoc_STR("Gets an entry from the cache or calls the factory function to produce one.")},

{"display", (PyCFunction)pysqlite_cache_display, METH_NOARGS,

PyDoc_STR("For debugging only.")},

{NULL, NULL}

};

PyTypeObject pysqlite_NodeType = {

PyVarObject_HEAD_INIT(NULL, 0)

MODULE_NAME "Node", /* tp_name */

sizeof(pysqlite_Node), /* tp_basicsize */

0, /* tp_itemsize */

(destructor)pysqlite_node_dealloc, /* tp_dealloc */

0, /* tp_vectorcall_offset */

0, /* tp_getattr */

0, /* tp_setattr */

0, /* tp_as_async */

0, /* tp_repr */

0, /* tp_as_number */

0, /* tp_as_sequence */

0, /* tp_as_mapping */

0, /* tp_hash */

0, /* tp_call */

0, /* tp_str */

0, /* tp_getattro */

0, /* tp_setattro */

0, /* tp_as_buffer */

Py_TPFLAGS_DEFAULT|Py_TPFLAGS_BASETYPE, /* tp_flags */

0, /* tp_doc */

0, /* tp_traverse */

0, /* tp_clear */

0, /* tp_richcompare */

0, /* tp_weaklistoffset */

0, /* tp_iter */

0, /* tp_iternext */

0, /* tp_methods */

0, /* tp_members */

0, /* tp_getset */

0, /* tp_base */

0, /* tp_dict */

0, /* tp_descr_get */

0, /* tp_descr_set */

0, /* tp_dictoffset */

(initproc)0, /* tp_init */

0, /* tp_alloc */

0, /* tp_new */

0 /* tp_free */

};

PyTypeObject pysqlite_CacheType = {

PyVarObject_HEAD_INIT(NULL, 0)

MODULE_NAME ".Cache", /* tp_name */

sizeof(pysqlite_Cache), /* tp_basicsize */

0, /* tp_itemsize */

(destructor)pysqlite_cache_dealloc, /* tp_dealloc */

0, /* tp_vectorcall_offset */

0, /* tp_getattr */

0, /* tp_setattr */

0, /* tp_as_async */

0, /* tp_repr */

0, /* tp_as_number */

0, /* tp_as_sequence */

0, /* tp_as_mapping */

0, /* tp_hash */

0, /* tp_call */

0, /* tp_str */

0, /* tp_getattro */

0, /* tp_setattro */

0, /* tp_as_buffer */

Py_TPFLAGS_DEFAULT|Py_TPFLAGS_BASETYPE, /* tp_flags */

0, /* tp_doc */

0, /* tp_traverse */

0, /* tp_clear */

0, /* tp_richcompare */

0, /* tp_weaklistoffset */

0, /* tp_iter */

0, /* tp_iternext */

cache_methods, /* tp_methods */

0, /* tp_members */

0, /* tp_getset */

0, /* tp_base */

0, /* tp_dict */

0, /* tp_descr_get */

0, /* tp_descr_set */

0, /* tp_dictoffset */

(initproc)pysqlite_cache_init, /* tp_init */

0, /* tp_alloc */

0, /* tp_new */

0 /* tp_free */

};

extern int pysqlite_cache_setup_types(void)

{

int rc;

pysqlite_NodeType.tp_new = PyType_GenericNew;

pysqlite_CacheType.tp_new = PyType_GenericNew;

rc = PyType_Ready(&pysqlite_NodeType);

if (rc < 0) {

return rc;

}

rc = PyType_Ready(&pysqlite_CacheType);

return rc;

}

cpython/Modules/_sqlite/cache.c at master · python-emscripten/cpython · GitHub

Repository navigation

Expand file tree

Breadcrumbs

cache.c

Latest commit

History

Breadcrumbs

cache.c

File metadata and controls