We have some use cases where plugins modifies cache keys, making it difficult
to see a unique identifier for a URL. Yes, you can log the full cache-key URL
as well, but often just getting the actual cache key hash is just as good. And
definitely more efficient.
I’m proposing a simple API to access this out of the HttpSM. The PR also has a
new log field to make logging this easy.
https://github.com/apache/trafficserver/pull/13134
— Leif
/**
Gets the effective cache key digest (cryptographic hash) that was
used for cache lookup or storage on this transaction. The digest
is returned as raw bytes — 16 bytes for MD5 (default) or 32 bytes
for SHA-256 (FIPS mode). A buffer of at least 32 bytes is
recommended to accommodate either configuration.
@param[in] txnp the transaction.
@param[out] buffer caller-provided buffer to receive the raw hash
bytes. If @c nullptr, only @a length is set (size query).
@param[in,out] length capacity of @a buffer in bytes on input; actual
digest size in bytes on output.
@return @c TS_SUCCESS if a cache key was computed for this
transaction, @c TS_ERROR if no cache lookup was performed or if
@a buffer is non-null and too small.
*/
TSReturnCode TSHttpTxnCacheKeyDigestGet(TSHttpTxn txnp, char *buffer, int
*length);
