extend artifact cache with non-key-included generations, to allow gracefully decaying certain computations

src/artifact_cache/artifact_cache.c

@@ -21,7 +21,7 @@ ac_init(void)
 //~ rjf: Cache Lookups
 
 internal void *
-ac_artifact_from_key(Access *access, String8 key, AC_CreateFunctionType *create, AC_DestroyFunctionType *destroy, U64 slots_count)
+ac_artifact_from_key(Access *access, String8 key, U64 gen, AC_CreateFunctionType *create, AC_DestroyFunctionType *destroy, U64 slots_count)
 {
   //- rjf: create function -> cache
   AC_Cache *cache = 0;
@@ -69,8 +69,10 @@ ac_artifact_from_key(Access *access, String8 key, AC_CreateFunctionType *create,
     for(B32 write_mode = 0; write_mode <= 1; write_mode += 1)
     {
       B32 found = 0;
+      B32 need_request = 0;
       RWMutexScope(stripe->rw_mutex, write_mode)
       {
+        // rjf: look up node
         for(AC_Node *n = slot->first; n != 0; n = n->next)
         {
           if(str8_match(n->key, key, 0))
@@ -78,11 +80,19 @@ ac_artifact_from_key(Access *access, String8 key, AC_CreateFunctionType *create,
             found = 1;
             artifact = n->val;
             access_touch(access, &n->access_pt, stripe->cv);
+            if(n->gen != gen)
+            {
+              B32 got_task = (ins_atomic_u64_eval_cond_assign(&n->working_count, 1, 0) == 0);
+              need_request = got_task;
+            }
             break;
           }
         }
+        
+        // rjf: no node? -> create
         if(write_mode && !found)
         {
+          need_request = 1;
           AC_Node *node = stripe->free;
           if(node)
           {
@@ -99,11 +109,9 @@ ac_artifact_from_key(Access *access, String8 key, AC_CreateFunctionType *create,
           node->working_count = 1;
         }
       }
-      if(found)
-      {
-        break;
-      }
-      else if(write_mode)
+      
+      // rjf: need request -> push
+      if(need_request)
       {
         MutexScope(ac_shared->req_mutex)
         {
@@ -111,10 +119,17 @@ ac_artifact_from_key(Access *access, String8 key, AC_CreateFunctionType *create,
           SLLQueuePush(ac_shared->first_req, ac_shared->last_req, n);
           ac_shared->req_count += 1;
           n->v.key = str8_copy(ac_shared->req_arena, key);
+          n->v.gen = gen;
           n->v.create = create;
         }
         cond_var_broadcast(async_tick_start_cond_var);
       }
+      
+      // rjf: found node -> break
+      if(found)
+      {
+        break;
+      }
     }
   }
   
@@ -240,6 +255,7 @@ ac_tick(void)
         {
           if(str8_match(n->key, reqs[idx].key, 0))
           {
+            n->gen = reqs[idx].gen;
             n->val = val;
             ins_atomic_u64_dec_eval(&n->working_count);
           }

src/artifact_cache/artifact_cache.h

@@ -17,6 +17,7 @@ typedef struct AC_Request AC_Request;
 struct AC_Request
 {
   String8 key;
+  U64 gen;
   AC_CreateFunctionType *create;
 };
 
@@ -33,8 +34,9 @@ struct AC_Node
   AC_Node *next;
   AC_Node *prev;
   
-  // rjf: key/value
+  // rjf: key/gen/value
   String8 key;
+  U64 gen;
   void *val;
   
   // rjf: metadata
@@ -94,7 +96,7 @@ internal void ac_init(void);
 ////////////////////////////////
 //~ rjf: Cache Lookups
 
-internal void *ac_artifact_from_key(Access *access, String8 key, AC_CreateFunctionType *create, AC_DestroyFunctionType *destroy, U64 slots_count);
+internal void *ac_artifact_from_key(Access *access, String8 key, U64 gen, AC_CreateFunctionType *create, AC_DestroyFunctionType *destroy, U64 slots_count);
 
 ////////////////////////////////
 //~ rjf: Tick

src/text_cache/text_cache.c

@@ -2252,7 +2252,7 @@ txt_text_info_from_hash_lang(Access *access, U128 hash, TXT_LangKind lang)
     TXT_LangKind lang;
   } key = {hash, lang};
   String8 key_string = str8_struct(&key);
-  TXT_Artifact *artifact = ac_artifact_from_key(access, key_string, txt_artifact_create, txt_artifact_destroy, 1024);
+  TXT_Artifact *artifact = ac_artifact_from_key(access, key_string, 0, txt_artifact_create, txt_artifact_destroy, 1024);
   TXT_TextInfo info = {0};
   if(artifact != 0)
   {

src/text_cache/text_cache.h

@@ -155,84 +155,6 @@ TXT_LangKind;
 
 typedef TXT_TokenArray TXT_LangLexFunctionType(Arena *arena, U64 *bytes_processed_counter, String8 string);
 
-////////////////////////////////
-//~ rjf: Cache Types
-
-typedef struct TXT_Request TXT_Request;
-struct TXT_Request
-{
-  U128 hash;
-  TXT_LangKind lang;
-};
-
-typedef struct TXT_RequestNode TXT_RequestNode;
-struct TXT_RequestNode
-{
-  TXT_RequestNode *next;
-  TXT_Request v;
-};
-
-typedef struct TXT_Node TXT_Node;
-struct TXT_Node
-{
-  // rjf: links
-  TXT_Node *next;
-  TXT_Node *prev;
-  
-  // rjf: key
-  U128 hash;
-  TXT_LangKind lang;
-  
-  // rjf: artifacts
-  Arena *arena;
-  TXT_TextInfo info;
-  
-  // rjf: metadata
-  AccessPt access_pt;
-  B32 is_working;
-  U64 load_count;
-};
-
-typedef struct TXT_Slot TXT_Slot;
-struct TXT_Slot
-{
-  TXT_Node *first;
-  TXT_Node *last;
-};
-
-////////////////////////////////
-//~ rjf: Shared State
-
-typedef struct TXT_Shared TXT_Shared;
-struct TXT_Shared
-{
-  Arena *arena;
-  
-  // rjf: cache
-  U64 slots_count;
-  TXT_Slot *slots;
-  StripeArray stripes;
-  TXT_Node **stripes_free_nodes;
-  
-  // rjf: requests
-  Mutex req_mutex;
-  Arena *req_arena;
-  TXT_RequestNode *first_req;
-  TXT_RequestNode *last_req;
-  U64 req_count;
-  
-  // rjf: user -> parse thread
-  U64 u2p_ring_size;
-  U8 *u2p_ring_base;
-  U64 u2p_ring_write_pos;
-  U64 u2p_ring_read_pos;
-  CondVar u2p_ring_cv;
-  Mutex u2p_ring_mutex;
-  
-  // rjf: evictor thread
-  Thread evictor_thread;
-};
-
 ////////////////////////////////
 //~ rjf: Globals