| # -*- coding: utf-8 -*- |
| """ |
| jinja2.bccache |
| ~~~~~~~~~~~~~~ |
| |
| This module implements the bytecode cache system Jinja is optionally |
| using. This is useful if you have very complex template situations and |
| the compiliation of all those templates slow down your application too |
| much. |
| |
| Situations where this is useful are often forking web applications that |
| are initialized on the first request. |
| |
| :copyright: (c) 2010 by the Jinja Team. |
| :license: BSD. |
| """ |
| from os import path, listdir |
| import sys |
| import marshal |
| import tempfile |
| import fnmatch |
| from hashlib import sha1 |
| from jinja2.utils import open_if_exists |
| from jinja2._compat import BytesIO, pickle, PY2, text_type |
| |
| |
| # marshal works better on 3.x, one hack less required |
| if not PY2: |
| marshal_dump = marshal.dump |
| marshal_load = marshal.load |
| else: |
| |
| def marshal_dump(code, f): |
| if isinstance(f, file): |
| marshal.dump(code, f) |
| else: |
| f.write(marshal.dumps(code)) |
| |
| def marshal_load(f): |
| if isinstance(f, file): |
| return marshal.load(f) |
| return marshal.loads(f.read()) |
| |
| |
| bc_version = 2 |
| |
| # magic version used to only change with new jinja versions. With 2.6 |
| # we change this to also take Python version changes into account. The |
| # reason for this is that Python tends to segfault if fed earlier bytecode |
| # versions because someone thought it would be a good idea to reuse opcodes |
| # or make Python incompatible with earlier versions. |
| bc_magic = 'j2'.encode('ascii') + \ |
| pickle.dumps(bc_version, 2) + \ |
| pickle.dumps((sys.version_info[0] << 24) | sys.version_info[1]) |
| |
| |
| class Bucket(object): |
| """Buckets are used to store the bytecode for one template. It's created |
| and initialized by the bytecode cache and passed to the loading functions. |
| |
| The buckets get an internal checksum from the cache assigned and use this |
| to automatically reject outdated cache material. Individual bytecode |
| cache subclasses don't have to care about cache invalidation. |
| """ |
| |
| def __init__(self, environment, key, checksum): |
| self.environment = environment |
| self.key = key |
| self.checksum = checksum |
| self.reset() |
| |
| def reset(self): |
| """Resets the bucket (unloads the bytecode).""" |
| self.code = None |
| |
| def load_bytecode(self, f): |
| """Loads bytecode from a file or file like object.""" |
| # make sure the magic header is correct |
| magic = f.read(len(bc_magic)) |
| if magic != bc_magic: |
| self.reset() |
| return |
| # the source code of the file changed, we need to reload |
| checksum = pickle.load(f) |
| if self.checksum != checksum: |
| self.reset() |
| return |
| self.code = marshal_load(f) |
| |
| def write_bytecode(self, f): |
| """Dump the bytecode into the file or file like object passed.""" |
| if self.code is None: |
| raise TypeError('can\'t write empty bucket') |
| f.write(bc_magic) |
| pickle.dump(self.checksum, f, 2) |
| marshal_dump(self.code, f) |
| |
| def bytecode_from_string(self, string): |
| """Load bytecode from a string.""" |
| self.load_bytecode(BytesIO(string)) |
| |
| def bytecode_to_string(self): |
| """Return the bytecode as string.""" |
| out = BytesIO() |
| self.write_bytecode(out) |
| return out.getvalue() |
| |
| |
| class BytecodeCache(object): |
| """To implement your own bytecode cache you have to subclass this class |
| and override :meth:`load_bytecode` and :meth:`dump_bytecode`. Both of |
| these methods are passed a :class:`~jinja2.bccache.Bucket`. |
| |
| A very basic bytecode cache that saves the bytecode on the file system:: |
| |
| from os import path |
| |
| class MyCache(BytecodeCache): |
| |
| def __init__(self, directory): |
| self.directory = directory |
| |
| def load_bytecode(self, bucket): |
| filename = path.join(self.directory, bucket.key) |
| if path.exists(filename): |
| with open(filename, 'rb') as f: |
| bucket.load_bytecode(f) |
| |
| def dump_bytecode(self, bucket): |
| filename = path.join(self.directory, bucket.key) |
| with open(filename, 'wb') as f: |
| bucket.write_bytecode(f) |
| |
| A more advanced version of a filesystem based bytecode cache is part of |
| Jinja2. |
| """ |
| |
| def load_bytecode(self, bucket): |
| """Subclasses have to override this method to load bytecode into a |
| bucket. If they are not able to find code in the cache for the |
| bucket, it must not do anything. |
| """ |
| raise NotImplementedError() |
| |
| def dump_bytecode(self, bucket): |
| """Subclasses have to override this method to write the bytecode |
| from a bucket back to the cache. If it unable to do so it must not |
| fail silently but raise an exception. |
| """ |
| raise NotImplementedError() |
| |
| def clear(self): |
| """Clears the cache. This method is not used by Jinja2 but should be |
| implemented to allow applications to clear the bytecode cache used |
| by a particular environment. |
| """ |
| |
| def get_cache_key(self, name, filename=None): |
| """Returns the unique hash key for this template name.""" |
| hash = sha1(name.encode('utf-8')) |
| if filename is not None: |
| filename = '|' + filename |
| if isinstance(filename, text_type): |
| filename = filename.encode('utf-8') |
| hash.update(filename) |
| return hash.hexdigest() |
| |
| def get_source_checksum(self, source): |
| """Returns a checksum for the source.""" |
| return sha1(source.encode('utf-8')).hexdigest() |
| |
| def get_bucket(self, environment, name, filename, source): |
| """Return a cache bucket for the given template. All arguments are |
| mandatory but filename may be `None`. |
| """ |
| key = self.get_cache_key(name, filename) |
| checksum = self.get_source_checksum(source) |
| bucket = Bucket(environment, key, checksum) |
| self.load_bytecode(bucket) |
| return bucket |
| |
| def set_bucket(self, bucket): |
| """Put the bucket into the cache.""" |
| self.dump_bytecode(bucket) |
| |
| |
| class FileSystemBytecodeCache(BytecodeCache): |
| """A bytecode cache that stores bytecode on the filesystem. It accepts |
| two arguments: The directory where the cache items are stored and a |
| pattern string that is used to build the filename. |
| |
| If no directory is specified the system temporary items folder is used. |
| |
| The pattern can be used to have multiple separate caches operate on the |
| same directory. The default pattern is ``'__jinja2_%s.cache'``. ``%s`` |
| is replaced with the cache key. |
| |
| >>> bcc = FileSystemBytecodeCache('/tmp/jinja_cache', '%s.cache') |
| |
| This bytecode cache supports clearing of the cache using the clear method. |
| """ |
| |
| def __init__(self, directory=None, pattern='__jinja2_%s.cache'): |
| if directory is None: |
| directory = tempfile.gettempdir() |
| self.directory = directory |
| self.pattern = pattern |
| |
| def _get_cache_filename(self, bucket): |
| return path.join(self.directory, self.pattern % bucket.key) |
| |
| def load_bytecode(self, bucket): |
| f = open_if_exists(self._get_cache_filename(bucket), 'rb') |
| if f is not None: |
| try: |
| bucket.load_bytecode(f) |
| finally: |
| f.close() |
| |
| def dump_bytecode(self, bucket): |
| f = open(self._get_cache_filename(bucket), 'wb') |
| try: |
| bucket.write_bytecode(f) |
| finally: |
| f.close() |
| |
| def clear(self): |
| # imported lazily here because google app-engine doesn't support |
| # write access on the file system and the function does not exist |
| # normally. |
| from os import remove |
| files = fnmatch.filter(listdir(self.directory), self.pattern % '*') |
| for filename in files: |
| try: |
| remove(path.join(self.directory, filename)) |
| except OSError: |
| pass |
| |
| |
| class MemcachedBytecodeCache(BytecodeCache): |
| """This class implements a bytecode cache that uses a memcache cache for |
| storing the information. It does not enforce a specific memcache library |
| (tummy's memcache or cmemcache) but will accept any class that provides |
| the minimal interface required. |
| |
| Libraries compatible with this class: |
| |
| - `werkzeug <http://werkzeug.pocoo.org/>`_.contrib.cache |
| - `python-memcached <http://www.tummy.com/Community/software/python-memcached/>`_ |
| - `cmemcache <http://gijsbert.org/cmemcache/>`_ |
| |
| (Unfortunately the django cache interface is not compatible because it |
| does not support storing binary data, only unicode. You can however pass |
| the underlying cache client to the bytecode cache which is available |
| as `django.core.cache.cache._client`.) |
| |
| The minimal interface for the client passed to the constructor is this: |
| |
| .. class:: MinimalClientInterface |
| |
| .. method:: set(key, value[, timeout]) |
| |
| Stores the bytecode in the cache. `value` is a string and |
| `timeout` the timeout of the key. If timeout is not provided |
| a default timeout or no timeout should be assumed, if it's |
| provided it's an integer with the number of seconds the cache |
| item should exist. |
| |
| .. method:: get(key) |
| |
| Returns the value for the cache key. If the item does not |
| exist in the cache the return value must be `None`. |
| |
| The other arguments to the constructor are the prefix for all keys that |
| is added before the actual cache key and the timeout for the bytecode in |
| the cache system. We recommend a high (or no) timeout. |
| |
| This bytecode cache does not support clearing of used items in the cache. |
| The clear method is a no-operation function. |
| |
| .. versionadded:: 2.7 |
| Added support for ignoring memcache errors through the |
| `ignore_memcache_errors` parameter. |
| """ |
| |
| def __init__(self, client, prefix='jinja2/bytecode/', timeout=None, |
| ignore_memcache_errors=True): |
| self.client = client |
| self.prefix = prefix |
| self.timeout = timeout |
| self.ignore_memcache_errors = ignore_memcache_errors |
| |
| def load_bytecode(self, bucket): |
| try: |
| code = self.client.get(self.prefix + bucket.key) |
| except Exception: |
| if not self.ignore_memcache_errors: |
| raise |
| code = None |
| if code is not None: |
| bucket.bytecode_from_string(code) |
| |
| def dump_bytecode(self, bucket): |
| args = (self.prefix + bucket.key, bucket.bytecode_to_string()) |
| if self.timeout is not None: |
| args += (self.timeout,) |
| try: |
| self.client.set(*args) |
| except Exception: |
| if not self.ignore_memcache_errors: |
| raise |
