PR11246 cont'd: Add options for cache control

--disable-cache : turn off all caching
--clean-cache   : clean up stale entries and then quit
--poison-cache  : force regeneration of items that would have hit the cache

These are undocumented for now, until we decide whether they are
generally useful.

* main.cxx (main): Parse the new options.
* session.h (systemtap_session): Add poison_cache; document the others.
* clean.cxx (clean_cache): No longer static.
  (get_stapconf_from_cache, get_script_from_cache): Respect poison.
* tapsets.cxx (tracepoint_builder::get_tracequery_module): Ditto.
  (dwarf_cast_expanding_visitor::filter_special_modules): Ditto.

1 files changed, 7 insertions, 6 deletions

diff --git a/session.h b/session.h
index ccf6c1da..1df94680 100644
--- a/session.h
+++ b/session.h
@@ -127,12 +127,13 @@ struct systemtap_session
   // and/or main.cxx(main).
 
   // Cache data
-  bool use_cache;
-  bool use_script_cache;
-  std::string cache_path;
-  std::string hash_path;
-  std::string stapconf_path;
-  hash *base_hash;
+  bool use_cache;               // control all caching
+  bool use_script_cache;        // control caching of pass-3/4 output
+  bool poison_cache;            // consider the cache to be write-only
+  std::string cache_path;       // usually ~/.systemtap/cache
+  std::string hash_path;        // path to the cached script module
+  std::string stapconf_path;    // path to the cached stapconf
+  hash *base_hash;              // hash common to all caching
 
   // dwarfless operation
   bool consult_symtab;