CacheBuilder Tool

CacheBuilder Tool

DeviceDetector.NET.CacheBuilder is a standalone CLI tool that pre-parses a list of known User-Agent strings and writes the results into the persistent LiteDB parse cache ahead of time. Ship the resulting .db file with your application to avoid paying the regex-parsing cost for your most common/expected UAs on first request.

This is conceptually similar to warming a cache from an access-log-derived UA list, a technique documented for the upstream PHP project — you can reuse the same approach to build your input file:

zcat /path/to/access/logs* | awk -F'"' '{print $6}' | sort | uniq -c | sort -rn | head -n20000 > top-user-agents.txt

Usage

DeviceDetector.NET.CacheBuilder -i <input-file> [options]

Option	Short	Default	Description
--input	-i	(required)	Text file with one User-Agent string per line
--output	-o	DeviceDetector.db	Output cache database filename
--yaml		(bundled rules)	Directory of YAML regex rule files to use instead of the bundled ones
--append	-a	false	Append to an existing cache database instead of overwriting it
--cacheTimeoutDays		365	How many days entries stay valid before expiring
--skipBotDetection		false	Apply DeviceDetector.SkipBotDetection() while building the cache (must match how you configure DeviceDetector at runtime — the flag affects the cache key)

Example

dotnet DeviceDetector.NET.CacheBuilder.dll -i top-user-agents.txt -o DeviceDetector.db --cacheTimeoutDays 90

This produces DeviceDetector.db. At runtime, point your app at the same directory/filename via DeviceDetectorSettings and set a matching (or longer) expiration so the pre-built entries remain valid:

using DeviceDetectorNET;

DeviceDetectorSettings.ParseCacheDBDirectory = @"C:\app\cache\";
DeviceDetectorSettings.ParseCacheDBFilename = "DeviceDetector.db";
DeviceDetectorSettings.ParseCacheDBExpiration = TimeSpan.FromDays(90);

Important: keep settings consistent

Because the persistent cache key incorporates parsing settings (notably SkipBotDetection), the flags used when building the cache must match the flags your application uses when consuming it — otherwise cached entries are effectively invisible (a cache miss) at runtime, silently falling back to live parsing. If you change SkipBotDetection or the YAML rule set version, rebuild the cache.

See Caching for how this fits alongside the fragment cache and the in-memory LRU cache.