Remove DB_MIN_CACHE because that's dumb.

You should be able to totally disable the cache if you so please. This
should ensure Telodendria uses less memory on constrained systems.

TODO.txt

@@ -13,9 +13,9 @@ Milestone: v0.2.0
 
 [ ] Abstract /email/requestToken and /msidsn/requestToken
 
-[~] Db API
+[x] Db API
     [x] If object is in cache, but doesn't exist on disk, delete from cache
-    [ ] Allow cache to be totally disabled (no MIN_CACHE_SIZE)
+    [x] Allow cache to be totally disabled (no MIN_CACHE_SIZE)
     [x] List keys under a path (DbList() using POSIX opendir())
 [~] User login
     [x] User manipulation functions (so we don't use the DB directly)

src/Db.c

@@ -328,7 +328,7 @@ DbOpen(char *dir, size_t cache)
 {
     Db *db;
 
-    if (!dir || cache < DB_MIN_CACHE)
+    if (!dir)
     {
         return NULL;
     }
@@ -344,14 +344,21 @@ DbOpen(char *dir, size_t cache)
 
     pthread_mutex_init(&db->lock, NULL);
 
-    db->cache = HashMapCreate();
-    if (!db->cache)
+    if (db->maxCache)
     {
-        return NULL;
-    }
+        db->cache = HashMapCreate();
+        if (!db->cache)
+        {
+            return NULL;
+        }
 
-    db->mostRecent = NULL;
-    db->leastRecent = NULL;
+        db->mostRecent = NULL;
+        db->leastRecent = NULL;
+    }
+    else
+    {
+        db->cache = NULL;
+    }
 
     return db;
 }
@@ -537,8 +544,6 @@ DbLockFromArr(Db * db, Array * args)
         pthread_mutex_init(&ref->lock, NULL);
         pthread_mutex_lock(&ref->lock);
 
-        ref->ts = UtilServerTs();
-        ref->size = DbComputeSize(ref->json);
 
         for (i = 0; i < ArraySize(args); i++)
         {
@@ -546,16 +551,21 @@ DbLockFromArr(Db * db, Array * args)
         }
         ref->name = name;
 
-        HashMapSet(db->cache, hash, ref);
-        db->cacheSize += ref->size;
+        if (db->cache)
+        {
+            ref->ts = UtilServerTs();
+            ref->size = DbComputeSize(ref->json);
+            HashMapSet(db->cache, hash, ref);
+            db->cacheSize += ref->size;
 
-        ref->next = NULL;
-        ref->prev = db->mostRecent;
-        db->mostRecent = ref;
+            ref->next = NULL;
+            ref->prev = db->mostRecent;
+            db->mostRecent = ref;
 
-        /* Adding this item to the cache may case it to grow too large,
-         * requiring some items to be evicted */
-        DbCacheEvict(db);
+            /* Adding this item to the cache may case it to grow too
+             * large, requiring some items to be evicted */
+            DbCacheEvict(db);
+        }
     }
 
 finish:
@@ -747,16 +757,28 @@ DbUnlock(Db * db, DbRef * ref)
     fflush(ref->fp);
     fclose(ref->fp);
 
-    db->cacheSize -= ref->size;
-    ref->size = DbComputeSize(ref->json);
-    db->cacheSize += ref->size;
+    if (db->cache)
+    {
+        db->cacheSize -= ref->size;
+        ref->size = DbComputeSize(ref->json);
+        db->cacheSize += ref->size;
 
-    pthread_mutex_unlock(&ref->lock);
+        /* If this ref has grown significantly since we last computed
+         * its size, it may have filled the cache and require some
+         * items to be evicted. */
+        DbCacheEvict(db);
+        pthread_mutex_unlock(&ref->lock);
+    }
+    else
+    {
+        JsonFree(ref->json);
+        StringArrayFree(ref->name);
 
-    /* If this ref has grown significantly since we last computed its
-     * size, it may have filled the cache and require some items to be
-     * evicted. */
-    DbCacheEvict(db);
+        pthread_mutex_unlock(&ref->lock);
+        pthread_mutex_destroy(&ref->lock);
+
+        Free(ref);
+    }
 
     pthread_mutex_unlock(&db->lock);
     return 1;

src/Telodendria.c

@@ -523,20 +523,11 @@ main(int argc, char **argv)
 
     if (!tConfig->maxCache)
     {
-        Log(lc, LOG_WARNING, "Max-cache is set to zero.");
+        Log(lc, LOG_WARNING, "Database caching is disabled.");
         Log(lc, LOG_WARNING,
             "If this is not what you intended, check the config file");
         Log(lc, LOG_WARNING,
-            "and ensure that max-cache is a valid number of bytes.");
-    }
-
-    if (tConfig->maxCache < DB_MIN_CACHE)
-    {
-        Log(lc, LOG_WARNING,
-            "Specified max cache size is less than the minimum of %d bytes.",
-            DB_MIN_CACHE);
-        Log(lc, LOG_WARNING, "Using a max-cache of %d bytes.", DB_MIN_CACHE);
-        tConfig->maxCache = DB_MIN_CACHE;
+            "and ensure that maxCache is a valid number of bytes.");
     }
 
     matrixArgs.db = DbOpen(".", tConfig->maxCache);

src/TelodendriaConfig.c

@@ -258,7 +258,7 @@ TelodendriaConfigParse(HashMap * config, LogConfig * lc)
 
     CONFIG_OPTIONAL_INTEGER(tConfig->threads, "threads", 1);
     CONFIG_OPTIONAL_INTEGER(tConfig->maxConnections, "maxConnections", 32);
-    CONFIG_OPTIONAL_INTEGER(tConfig->maxCache, "maxCache", DB_MIN_CACHE);
+    CONFIG_OPTIONAL_INTEGER(tConfig->maxCache, "maxCache", 0);
 
     CONFIG_REQUIRE("federation", JSON_BOOLEAN);
     if (JsonValueAsBoolean(value))

src/include/Db.h

@@ -24,10 +24,6 @@
 #ifndef TELODENDRIA_DB_H
 #define TELODENDRIA_DB_H
 
-#ifndef DB_MIN_CACHE
-#define DB_MIN_CACHE 1024
-#endif
-
 #include <stddef.h>
 
 #include <HashMap.h>