Merge branch 'lmdbwerk' of https://git.telodendria.io/lda/Cytoplasm into lmdbwerk

Yeah, I was stupid for not doing that earlier.

include/Cytoplasm/Db.h

@@ -48,6 +48,17 @@
  */
 typedef struct Db Db;
 
+/**
+ * Some "hints" for the database backend for operations. 
+ * Hints are a way for the program to declare what to except of it
+ * (and the program MUST adhere to these hints, but the backend 
+ * MAY adhere).
+ */
+typedef enum DbHint {
+    DB_HINT_READONLY,   /* The database reference is treated as read-only */
+    DB_HINT_WRITE       /* The database reference is treated as read/write */
+} DbHint;
+
 /**
  * When an object is locked, a reference is returned. This reference
  * is owned by the current thread, and the database is inaccessible to
@@ -118,6 +129,15 @@ extern DbRef * DbCreate(Db *, size_t,...);
  */
 extern DbRef * DbLock(Db *, size_t,...);
 
+/**
+ * Behaves like
+ * .Fn DbLock ,
+ * but with hints on the reference itself, as 
+ * .Fn DbLock 
+ * itself is read/write.
+ */
+extern DbRef * DbLockIntent(Db *, DbHint, size_t,...);
+
 /**
  * Immediately and permanently remove an object from the database.
  * This function assumes the object is not locked, otherwise undefined

src/Db/Db.c

@@ -327,7 +327,30 @@ DbLock(Db * db, size_t nArgs,...)
         return NULL;
     }
 
-    ret = db->lockFunc(db, args);
+    ret = db->lockFunc(db, DB_HINT_WRITE, args);
+
+    ArrayFree(args);
+
+    return ret;
+}
+
+DbRef *
+DbLockIntent(Db * db, DbHint hint, size_t nArgs,...)
+{
+    va_list ap;
+    Array *args;
+    DbRef *ret;
+
+    va_start(ap, nArgs);
+    args = ArrayFromVarArgs(nArgs, ap);
+    va_end(ap);
+
+    if (!args || !db->lockFunc)
+    {
+        return NULL;
+    }
+
+    ret = db->lockFunc(db, hint, args);
 
     ArrayFree(args);
 

src/Db/Flat.c

@@ -101,7 +101,7 @@ DbFileName(FlatDb * db, Array * args)
 }
 
 static DbRef *
-FlatLock(Db *d, Array *dir)
+FlatLock(Db *d, DbHint hint, Array *dir)
 {
     FlatDb *db = (FlatDb *) d;
     FlatDbRef *ref = NULL;
@@ -146,6 +146,8 @@ FlatLock(Db *d, Array *dir)
 
         ref = Malloc(sizeof(*ref));
         DbRefInit(d, (DbRef *) ref);
+        /* TODO: Hints */
+        ref->base.hint = hint;
         ref->base.ts = UtilLastModified(path);
         ref->base.json = JsonDecode(stream);
         ref->stream = stream;
@@ -248,7 +250,7 @@ FlatCreate(Db *d, Array *dir)
 
     /* FlatLock() will lock again for us */
     pthread_mutex_unlock(&d->lock);
-    ret = FlatLock(d, dir);
+    ret = FlatLock(d, DB_HINT_WRITE, dir);
 
     return ret;
 }

src/Db/Internal.h

@@ -66,7 +66,7 @@ struct Db
 
     /* Functions for implementation-specific operations
      * (opening a ref, closing a db, removing an entry, ...) */
-    DbRef * (*lockFunc)(Db *, Array *);
+    DbRef * (*lockFunc)(Db *, DbHint, Array *);
     DbRef * (*create)(Db *, Array *);
     Array * (*list)(Db *, Array *);
     bool (*unlock)(Db *, DbRef *);
@@ -89,8 +89,7 @@ struct DbRef
     DbRef *prev;
     DbRef *next;
 
-    /* TODO: Functions for implementation-specific operations */
-
+    DbHint hint;
     /* Implementation-specific constructs */
 };
 

src/Db/LMDB.c

@@ -17,6 +17,7 @@ typedef struct LMDB {
     Db base; /* The base implementation required to pass */
 
     MDB_env *environ;
+    MDB_dbi dbi;
 } LMDB;
 typedef struct LMDBRef {
     DbRef base;
@@ -135,14 +136,13 @@ LMDBKeyHead(MDB_val key)
 }
 
 static DbRef *
-LMDBLock(Db *d, Array *k)
+LMDBLock(Db *d, DbHint hint, Array *k)
 {
     LMDB *db = (LMDB *) d;
     MDB_txn *transaction;
     LMDBRef *ret = NULL;
-    MDB_val key, empty_json;
-    MDB_dbi dbi;
-    int code;
+    MDB_val key, json_val;
+    int code, flags;
     if (!d || !k)
     {
         return NULL;
@@ -151,8 +151,11 @@ LMDBLock(Db *d, Array *k)
     pthread_mutex_lock(&d->lock);
     key = LMDBTranslateKey(k);
 
-    /* create a txn */
-    if ((code = mdb_txn_begin(db->environ, NULL, 0, &transaction)) != 0)
+    /* Create a transaction, honoring hints. */
+    /* TODO: Do we want to create a "main" transaction that everyone inherits 
+     * from? */
+    flags = hint == DB_HINT_READONLY ? MDB_RDONLY : 0;
+    if ((code = mdb_txn_begin(db->environ, NULL, flags, &transaction)) != 0)
     {
         /* Very bad! */
         Log(LOG_ERR,
@@ -161,25 +164,13 @@ LMDBLock(Db *d, Array *k)
         );
         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;
-    }
 
-    empty_json.mv_size = 0;
-    empty_json.mv_data = NULL;
-    /* get data from it */
-    code = mdb_get(transaction, dbi, &key, &empty_json);
+    json_val.mv_size = 0;
+    json_val.mv_data = NULL;
+    code = mdb_get(transaction, db->dbi, &key, &json_val);
     if (code == MDB_NOTFOUND)
     {
-        /* No use logging it, as that is just locking behaviour */
         mdb_txn_abort(transaction);
-        mdb_dbi_close(db->environ, dbi);
         goto end;
     }
     else if (code != 0)
@@ -189,7 +180,6 @@ LMDBLock(Db *d, Array *k)
             __func__, mdb_strerror(code)
         );
         mdb_txn_abort(transaction);
-        mdb_dbi_close(db->environ, dbi);
         goto end;
     }
 
@@ -205,11 +195,20 @@ LMDBLock(Db *d, Array *k)
             StringArrayAppend(ret->base.name, ent);
         }
     }
-    ret->base.json = LMDBDecode(empty_json);
-    ret->transaction = transaction;
-    ret->dbi = dbi;
+    ret->base.json = LMDBDecode(json_val);
+    ret->base.hint = hint;
+    ret->transaction = NULL;
+
+    if (hint == DB_HINT_WRITE)
+    {
+        ret->transaction = transaction;
+    }
+    else
+    {
+        mdb_txn_abort(transaction);
+    }
 end:
-    if (!ret)
+    if (!ret || hint == DB_HINT_READONLY)
     {
         pthread_mutex_unlock(&d->lock);
     }
@@ -222,7 +221,6 @@ 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)
@@ -243,21 +241,9 @@ LMDBExists(Db *d, Array *k)
         );
         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;
+    ret = mdb_get(transaction, db->dbi, &key, &empty) == 0;
     mdb_txn_abort(transaction);
-    mdb_dbi_close(db->environ, dbi);
-
 end:
     LMDBKillKey(key);
     pthread_mutex_unlock(&d->lock);
@@ -269,7 +255,6 @@ 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)
@@ -290,21 +275,9 @@ LMDBDelete(Db *d, Array *k)
         );
         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;
+    ret = mdb_del(transaction, db->dbi, &key, &empty) == 0;
     mdb_txn_commit(transaction);
-    mdb_dbi_close(db->environ, dbi);
-
 end:
     LMDBKillKey(key);
     pthread_mutex_unlock(&d->lock);
@@ -319,7 +292,7 @@ LMDBUnlock(Db *d, DbRef *r)
     FILE *fakestream;
     Stream *stream;
     MDB_val key, val;
-    bool ret;
+    bool ret = true;
 
     if (!d || !r)
     {
@@ -328,28 +301,30 @@ LMDBUnlock(Db *d, DbRef *r)
 
     val.mv_data = NULL;
     val.mv_size = 0;
-    key = LMDBTranslateKey(r->name);
+    if (ref->transaction && r->hint == DB_HINT_WRITE)
+    {
+        key = LMDBTranslateKey(r->name);
 
-    fakestream = open_memstream((char **) &val.mv_data, &val.mv_size);
-    stream = StreamFile(fakestream);
-    JsonEncode(r->json, stream, JSON_DEFAULT);
-    StreamFlush(stream);
-    StreamClose(stream);
+        fakestream = open_memstream((char **) &val.mv_data, &val.mv_size);
+        stream = StreamFile(fakestream);
+        JsonEncode(r->json, stream, JSON_DEFAULT);
+        StreamFlush(stream);
+        StreamClose(stream);
 
-    ret = mdb_put(ref->transaction, ref->dbi, &key, &val, 0) == 0;
+        ret = mdb_put(ref->transaction, db->dbi, &key, &val, 0) == 0;
 
-    mdb_txn_commit(ref->transaction);
-    mdb_dbi_close(db->environ, ref->dbi);
+        mdb_txn_commit(ref->transaction);
+        LMDBKillKey(key);
+    }
     StringArrayFree(ref->base.name);
     JsonFree(ref->base.json);
     Free(ref);
 
-    LMDBKillKey(key);
     if (val.mv_data)
     {
         free(val.mv_data);
     }
-    if (ret)
+    if (ret && r->hint == DB_HINT_WRITE)
     {
         pthread_mutex_unlock(&d->lock);
     }
@@ -362,7 +337,6 @@ LMDBCreate(Db *d, Array *k)
     MDB_txn *transaction;
     LMDBRef *ret = NULL;
     MDB_val key, empty_json;
-    MDB_dbi dbi;
     int code;
     if (!d || !k)
     {
@@ -382,38 +356,25 @@ LMDBCreate(Db *d, Array *k)
         );
         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;
-
-    }
 
     empty_json.mv_size = 2;
     empty_json.mv_data = "{}";
     /* put data in it */
-    code = mdb_put(transaction, dbi, &key, &empty_json, MDB_NOOVERWRITE);
+    code = mdb_put(transaction, db->dbi, &key, &empty_json, MDB_NOOVERWRITE);
     if (code == MDB_KEYEXIST)
     {
-        mdb_dbi_close(db->environ, dbi);
         mdb_txn_abort(transaction);
         goto end;
     }
     else if (code == MDB_MAP_FULL)
     {
         Log(LOG_ERR, "%s: db is full", __func__);
-        mdb_dbi_close(db->environ, dbi);
         mdb_txn_abort(transaction);
         goto end;
     }
     else if (code != 0)
     {
         Log(LOG_ERR, "%s: mdb_put failure: %s", __func__, mdb_strerror(code));
-        mdb_dbi_close(db->environ, dbi);
         mdb_txn_abort(transaction);
         goto end;
     }
@@ -430,9 +391,9 @@ LMDBCreate(Db *d, Array *k)
             StringArrayAppend(ret->base.name, ent);
         }
     }
+    ret->base.hint = DB_HINT_WRITE;
     ret->base.json = HashMapCreate();
     ret->transaction = transaction;
-    ret->dbi = dbi;
 end:
     if (!ret)
     {
@@ -454,7 +415,6 @@ LMDBList(Db *d, Array *k)
     MDB_cursor *cursor;
     MDB_cursor_op op = MDB_SET_RANGE;
     MDB_txn *txn;
-    MDB_dbi dbi;
     int code;
 
     if (!d || !k)
@@ -475,24 +435,13 @@ LMDBList(Db *d, Array *k)
         );
         goto end;
     }
-    /* apparently you need to give it a dbi */
-    if ((code = mdb_dbi_open(txn, "db", MDB_CREATE, &dbi)) != 0)
-    {
-        Log(LOG_ERR,
-            "%s: could not get transaction dbi: %s",
-            __func__, mdb_strerror(code)
-        );
-        mdb_txn_abort(txn);
-        goto end;
-    }
-    if ((code = mdb_cursor_open(txn, dbi, &cursor)) != 0)
+    if ((code = mdb_cursor_open(txn, db->dbi, &cursor)) != 0)
     {
         Log(LOG_ERR,
             "%s: could not get cursor: %s",
             __func__, mdb_strerror(code)
         );
         mdb_txn_abort(txn);
-        mdb_dbi_close(db->environ, dbi);
         goto end;
     }
 
@@ -520,7 +469,6 @@ LMDBList(Db *d, Array *k)
 
     mdb_cursor_close(cursor);
     mdb_txn_abort(txn);
-    mdb_dbi_close(db->environ, dbi);
 
 end:
     LMDBKillKey(key);
@@ -538,6 +486,7 @@ LMDBClose(Db *d)
         return;
     }
 
+    mdb_dbi_close(db->environ, db->dbi);
     mdb_env_close(db->environ);
 }
 
@@ -546,6 +495,8 @@ DbOpenLMDB(char *dir, size_t size)
 {
     /* TODO */
     MDB_env *env = NULL;
+    MDB_txn *txn;
+    MDB_dbi dbi;
     int code;
     LMDB *db;
     if (!dir || !size)
@@ -583,10 +534,35 @@ DbOpenLMDB(char *dir, size_t size)
         return NULL;
     }
 
+    /* Initialise a DBI */
+    {
+        if ((code = mdb_txn_begin(env, NULL, 0, &txn)) != 0)
+        {
+            Log(LOG_ERR,
+                "%s: could not begin transaction: %s",
+                __func__, mdb_strerror(code)
+            );
+            mdb_env_close(env);
+            return NULL;
+        }
+        if ((code = mdb_dbi_open(txn, "db", MDB_CREATE, &dbi)) != 0)
+        {
+            Log(LOG_ERR,
+                "%s: could not get transaction dbi: %s",
+                __func__, mdb_strerror(code)
+            );
+            mdb_txn_abort(txn);
+            mdb_env_close(env);
+            return NULL;
+        }
+        mdb_txn_commit(txn);
+    }
+
 
     db = Malloc(sizeof(*db));
     DbInit((Db *) db);
     db->environ = env;
+    db->dbi = dbi;
 
     db->base.lockFunc = LMDBLock;
     db->base.create = LMDBCreate;