plone.memoize helpers with support for plone.subrequest

memoize.py

# -*- coding: utf-8 -*-

# memoize support for plone.subrequest subrequests.
# usage:
# >>> import ./memoize
# >>> from ./memoize import instance_memoize
# >>> @memoize.parent_request_memoize
# >>> def _results(self):
# >>>     return "expensive calculation"
# >>>
# >>> @memoize.instance_memoize
# >>> def results(self):
# >>>     return "another expensive calculation"

from Products.CMFPlone.utils import get_top_request
from zope.annotation.interfaces import IAnnotations


parent_request_memo_key = "_parentrequest_memoizer"
instance_memo_pre = "__memoize__"
_marker = object()


def parent_request_memoize(func):
    def memogetter(*args, **kwargs):
        instance = args[0]
        context = getattr(instance, "context", None)
        request = getattr(instance, "request", None)

        request = get_top_request(request)

        annotations = IAnnotations(request)
        cache = annotations.get(parent_request_memo_key, _marker)

        if cache is _marker:
            cache = annotations[parent_request_memo_key] = dict()

        key = (
            context.getPhysicalPath(),
            instance.__class__.__name__,
            func.__name__,
            args[1:],
            frozenset(kwargs.items()),
        )
        value = cache.get(key, _marker)
        if value is _marker:
            value = cache[key] = func(*args, **kwargs)
        return value

    return memogetter


def parent_request_memoize_contextless(func):
    def memogetter(*args, **kwargs):
        instance = args[0]
        request = getattr(instance, "request", None)

        request = get_top_request(request)

        annotations = IAnnotations(request)
        cache = annotations.get(parent_request_memo_key, _marker)

        if cache is _marker:
            cache = annotations[parent_request_memo_key] = dict()

        key = (
            instance.__class__.__name__,
            func.__name__,
            args[1:],
            frozenset(kwargs.items()),
        )
        value = cache.get(key, _marker)
        if value is _marker:
            value = cache[key] = func(*args, **kwargs)
        return value

    return memogetter


def instance_memoize(func):
    # TODO: make sure, this isn't causing a transaction.commit() and DB write.
    def memogetter(*args, **kwargs):
        instance = args[0]
        key = instance_memo_pre + func.__name__
        if getattr(instance, key, _marker) == _marker:
            setattr(instance, key, func(*args, **kwargs))
        return getattr(instance, key)

    return memogetter