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GPT on behalf of DHH
25 lines
1.2 KiB
Ruby
25 lines
1.2 KiB
Ruby
# Rebuild request-local models from bounded, immutable database snapshots.
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# The observer must still see the captured epoch after lookup and admission.
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class RecordCache
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def self.fetch(key, version)
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return yield unless version && ResponseCache.instance.budget.positive? && !ActiveRecord::Base.connection_pool.active_connection?&.transaction_open?
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key = ActiveSupport::Cache.expand_cache_key([ "record-snapshot-v1", version, key ])
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return yield if key.bytesize > ResponseCache::MAX_KEY_BYTES
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if snapshot = FragmentCache.store.read(key)
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if ResponseCache.instance.version == version
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return ActiveSupport::JSON.decode(snapshot).map { |name, attributes| name.constantize.instantiate(attributes) }
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end
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end
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records = yield
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if records.all? { |record| record&.persisted? && !record.changed? } && ResponseCache.instance.version == version
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# Raw database values retain timestamp precision and native enum binding.
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snapshot = ActiveSupport::JSON.encode(records.map { |record| [ record.class.name, record.attributes_before_type_cast ] })
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FragmentCache.store.write(key, snapshot) if snapshot.bytesize <= ResponseCache::MAX_ENTRY_BYTES
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end
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records
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end
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end
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