Django nodes cache #40
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Co-authored-by: Patrick Cloke <clokep@users.noreply.github.com>
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Looks like this needs |
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Yes, I ran black and fixed the formatting. |
| @@ -99,7 +119,7 @@ def _render_template_block_nodelist(nodelist, block_name, context): | |||
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| # If the name matches, you're all set and we found the block! | |||
| if node.name == block_name: | |||
| return node.render(context) | |||
| return node, context.render_context | |||
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I'm having some trouble wrapping my brain around some of this change, it seems like _find_template_block_nodelist really only cares about the render_context after this change and not the context itself.
(This is also true of _find_template_block.)
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The Context/RequestContext has the data to be rendered. The context.render_context has only the template structure that can be reused, so I always need a new Context, but can reuse the render context.
| return _render_template_block(template, block_name, context_instance) | ||
| except BlockNotFound: | ||
| # The block wasn't found in the current template. | ||
| node, render_context = _NODES_CACHE[cache_key] |
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I'm slightly worried that a global cache might not be safe to use here, but it likely is OK in almost every case.
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I agree. Django has a cache per instance of template cached loader. https://github.com/django/django/blob/21d8ea4eb3e22d458515b5278c8cd3a15b069799/django/template/loaders/cached.py#L16
Django template loaders have to handle multiple loader instances and do things like template overriding, that are impossible with a global cache.
This lib is a lot simpler than Django template loaders, so the global cache would work fine.
| if not template.engine.debug: | ||
| _NODES_CACHE[cache_key] = node, render_context | ||
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| context_instance.render_context = render_context |
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There's a comment added in #25 that implies reusing render contexts might be unsafe. That does have a test though so hopefully it is OK.
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I think it is ok.
The issue #25 fixed Context object reuse, but we're just reusing the render_context inside a new Context. https://github.com/django/django/blob/main/django/template/loaders/cached.py#L72
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I added a commit here to support anonymous templates. It is a case where |
It is really slow to parse templates everytime you call
render_blockand it is a static information, so you can cache it in memory.I did some benchmarking here and this node cache improved performance ~20%.
Most part of the work was done by @walison17, I just wrote a test and did the benckmark.