[ADD/WIP] Most DB operations for LMDB

Somewhat untested. I want to go on a test run soon.

Next up: aargh... listing... The one thing LMDB may suck at.

src/Db/LMDB.c

@@ -68,6 +68,203 @@ LMDBKillKey(MDB_val key)
 
     Free(key.mv_data);
 }
+static HashMap *
+LMDBDecode(MDB_val val)
+{
+    FILE *fakefile;
+    Stream *fakestream;
+    HashMap *ret;
+    if (!val.mv_data || !val.mv_size)
+    {
+        return NULL;
+    }
+
+    fakefile = fmemopen(val.mv_data, val.mv_size, "r");
+    fakestream = StreamFile(fakefile);
+    ret = JsonDecode(fakestream);
+    StreamClose(fakestream);
+
+    return ret;
+}
+
+static DbRef *
+LMDBLock(Db *d, Array *k)
+{
+    LMDB *db = (LMDB *) d;
+    MDB_txn *transaction;
+    LMDBRef *ret = NULL;
+    MDB_val key, empty_json;
+    MDB_dbi dbi;
+    int code;
+    if (!d || !k)
+    {
+        return NULL;
+    }
+
+    pthread_mutex_lock(&d->lock);
+    key = LMDBTranslateKey(k);
+
+    /* create a txn */
+    if ((code = mdb_txn_begin(db->environ, NULL, 0, &transaction)) != 0)
+    {
+        /* Very bad! */
+        Log(LOG_ERR,
+            "%s: could not begin transaction: %s",
+            __func__, mdb_strerror(code)
+        );
+        pthread_mutex_unlock(&d->lock);
+        goto end;
+    }
+    /* apparently you need to give it a dbi */
+    if ((code = mdb_dbi_open(transaction, "db", MDB_CREATE, &dbi)) != 0)
+    {
+        Log(LOG_ERR,
+            "%s: could not get transaction dbi: %s",
+            __func__, mdb_strerror(code)
+        );
+        pthread_mutex_unlock(&d->lock);
+        goto end;
+
+    }
+
+    empty_json.mv_size = 0;
+    empty_json.mv_data = NULL;
+    /* get data from it */
+    code = mdb_get(transaction, dbi, &key, &empty_json);
+    if (code == MDB_NOTFOUND)
+    {
+        Log(LOG_ERR, 
+            "%s: mdb_get failure: %s", 
+            __func__, mdb_strerror(code)
+        );
+        mdb_txn_abort(transaction);
+        mdb_dbi_close(db->environ, dbi);
+        goto end;
+    }
+    else if (code != 0)
+    {
+        Log(LOG_ERR, 
+            "%s: mdb_get failure: %s", 
+            __func__, mdb_strerror(code)
+        );
+        mdb_txn_abort(transaction);
+        mdb_dbi_close(db->environ, dbi);
+        goto end;
+    }
+
+    ret = Malloc(sizeof(*ret));
+    DbRefInit(d, (DbRef *) ret);
+    /* TODO: Timestamp */
+    {
+        size_t i;
+        ret->base.name = ArrayCreate();
+        for (i = 0; i < ArraySize(k); i++)
+        {
+            char *ent = ArrayGet(k, i);
+            StringArrayAppend(ret->base.name, ent);
+        }
+    }
+    ret->base.json = LMDBDecode(empty_json);
+    ret->transaction = transaction;
+    ret->dbi = dbi;
+end:
+    LMDBKillKey(key);
+    return (DbRef *) ret;
+}
+static bool
+LMDBExists(Db *d, Array *k)
+{
+    MDB_val key, empty;
+    LMDB *db = (LMDB *) d;
+    MDB_txn *transaction;
+    MDB_dbi dbi;
+    int code;
+    bool ret = false;
+    if (!d || !k)
+    {
+        return false;
+    }
+
+    pthread_mutex_lock(&d->lock);
+    key = LMDBTranslateKey(k);
+
+    /* create a txn */
+    if ((code = mdb_txn_begin(db->environ, NULL, 0, &transaction)) != 0)
+    {
+        /* Very bad! */
+        Log(LOG_ERR,
+            "%s: could not begin transaction: %s",
+            __func__, mdb_strerror(code)
+        );
+        goto end;
+    }
+    /* apparently you need to give it a dbi */
+    if ((code = mdb_dbi_open(transaction, "db", MDB_CREATE, &dbi)) != 0)
+    {
+        Log(LOG_ERR,
+            "%s: could not get transaction dbi: %s",
+            __func__, mdb_strerror(code)
+        );
+        goto end;
+
+    }
+
+    ret = mdb_get(transaction, dbi, &key, &empty) == 0;
+    mdb_txn_abort(transaction);
+    mdb_dbi_close(db->environ, dbi);
+
+end:
+    LMDBKillKey(key);
+    pthread_mutex_unlock(&d->lock);
+    return ret;
+}
+static bool
+LMDBDelete(Db *d, Array *k)
+{
+    MDB_val key, empty;
+    LMDB *db = (LMDB *) d;
+    MDB_txn *transaction;
+    MDB_dbi dbi;
+    int code;
+    bool ret = false;
+    if (!d || !k)
+    {
+        return false;
+    }
+
+    pthread_mutex_lock(&d->lock);
+    key = LMDBTranslateKey(k);
+
+    /* create a txn */
+    if ((code = mdb_txn_begin(db->environ, NULL, 0, &transaction)) != 0)
+    {
+        /* Very bad! */
+        Log(LOG_ERR,
+            "%s: could not begin transaction: %s",
+            __func__, mdb_strerror(code)
+        );
+        goto end;
+    }
+    /* apparently you need to give it a dbi */
+    if ((code = mdb_dbi_open(transaction, "db", MDB_CREATE, &dbi)) != 0)
+    {
+        Log(LOG_ERR,
+            "%s: could not get transaction dbi: %s",
+            __func__, mdb_strerror(code)
+        );
+        goto end;
+
+    }
+
+    ret = mdb_del(transaction, dbi, &key, &empty) == 0;
+    mdb_txn_commit(transaction);
+    mdb_dbi_close(db->environ, dbi);
+
+end:
+    LMDBKillKey(key);
+    pthread_mutex_unlock(&d->lock);
+    return ret;
+}
 
 static bool
 LMDBUnlock(Db *d, DbRef *r)
@@ -256,13 +453,13 @@ DbOpenLMDB(char *dir, size_t size)
     DbInit((Db *) db);
     db->environ = env;
 
-    db->base.lockFunc = NULL;
+    db->base.lockFunc = LMDBLock;
     db->base.create = LMDBCreate;
     db->base.unlock = LMDBUnlock;
-    db->base.delete = NULL;
+    db->base.delete = LMDBDelete;
-    db->base.exists = NULL;
+    db->base.exists = LMDBExists;
     db->base.close = LMDBClose;
-    db->base.list = NULL;
+    db->base.list = NULL; /* TODO: This one is gonna be Fun. */
     
     return (Db *) db;
 }