Adrian A. Baumann
020dff0871
- Implement content-based hashing for cache keys - POST diagram content to Kroki server instead of URL encoding - Store generated SVGs in local filesystem cache - Add cache clearing functionality
92 lines
3.0 KiB
Python
92 lines
3.0 KiB
Python
import hashlib
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import os
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import requests
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from pathlib import Path
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from django.conf import settings
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from django.core.files.storage import default_storage
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from django.core.files.base import ContentFile
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import logging
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logger = logging.getLogger(__name__)
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# Configure cache directory
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CACHE_DIR = getattr(settings, 'DIAGRAM_CACHE_DIR', 'diagram_cache')
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KROKI_UPSTREAM = "http://svckroki:8000"
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def get_cache_path(diagram_type, content_hash):
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"""Generate cache file path for a diagram."""
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return os.path.join(CACHE_DIR, diagram_type, f"{content_hash}.svg")
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def compute_hash(content):
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"""Compute SHA256 hash of diagram content."""
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return hashlib.sha256(content.encode('utf-8')).hexdigest()
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def get_cached_diagram(diagram_type, diagram_content):
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"""
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Retrieve diagram from cache or generate it via POST.
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Args:
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diagram_type: Type of diagram (e.g., 'plantuml', 'mermaid')
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diagram_content: Raw diagram content
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Returns:
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Path to cached diagram file (relative to MEDIA_ROOT)
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"""
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content_hash = compute_hash(diagram_content)
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cache_path = get_cache_path(diagram_type, content_hash)
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# Check if diagram exists in cache
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if default_storage.exists(cache_path):
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logger.debug(f"Cache hit for {diagram_type} diagram: {content_hash[:8]}")
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return cache_path
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# Generate diagram via POST request
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logger.info(f"Cache miss for {diagram_type} diagram: {content_hash[:8]}, generating...")
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try:
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url = f"{KROKI_UPSTREAM}/{diagram_type}/svg"
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response = requests.post(
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url,
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data=diagram_content.encode('utf-8'),
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headers={'Content-Type': 'text/plain'},
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timeout=30
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)
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response.raise_for_status()
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# Ensure cache directory exists
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cache_dir = os.path.dirname(default_storage.path(cache_path))
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os.makedirs(cache_dir, exist_ok=True)
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# Save to cache
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default_storage.save(cache_path, ContentFile(response.content))
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logger.info(f"Diagram cached successfully: {cache_path}")
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return cache_path
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except requests.RequestException as e:
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logger.error(f"Error generating diagram: {e}")
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raise
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def clear_cache(diagram_type=None):
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"""
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Clear cached diagrams.
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Args:
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diagram_type: If specified, only clear diagrams of this type
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"""
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if diagram_type:
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cache_path = os.path.join(CACHE_DIR, diagram_type)
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else:
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cache_path = CACHE_DIR
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if default_storage.exists(cache_path):
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full_path = default_storage.path(cache_path)
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# Walk through and delete files
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for root, dirs, files in os.walk(full_path):
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for file in files:
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file_path = os.path.join(root, file)
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try:
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os.remove(file_path)
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logger.info(f"Deleted cached diagram: {file_path}")
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except OSError as e:
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logger.error(f"Error deleting {file_path}: {e}")
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