Begin implementation of the STABLE operation

blockstore_stable.cpp

@@ -0,0 +1,55 @@
+#include "blockstore.h"
+
+int blockstore::dequeue_stable(blockstore_operation *op)
+{
+    auto dirty_it = dirty_db.find((obj_ver_id){
+        .oid = op->oid,
+        .version = op->version,
+    });
+    if (dirty_it == dirty_db.end())
+    {
+        auto clean_it = object_db.find(op->oid);
+        if (clean_it == object_db.end() || clean_it->second.version < op->version)
+        {
+            // No such object version
+            op->retval = EINVAL;
+        }
+        else
+        {
+            // Already stable
+            op->retval = 0;
+        }
+        op->callback(op);
+        return 1;
+    }
+    else if (IS_UNSYNCED(dirty_it->second.state))
+    {
+        // Object not synced yet. Caller must sync it first
+        op->retval = EAGAIN;
+        op->callback(op);
+        return 1;
+    }
+    else if (IS_STABLE(dirty_it->second.state))
+    {
+        // Already stable
+        op->retval = 0;
+        op->callback(op);
+        return 1;
+    }
+    return 0;
+}
+
+void blockstore::handle_stable_event(ring_data_t *data, blockstore_operation *op)
+{
+    if (data->res < 0)
+    {
+        // sync error
+        // FIXME: our state becomes corrupted after a write error. maybe do something better than just die
+        throw new std::runtime_error("write operation failed. in-memory state is corrupted. AAAAAAAaaaaaaaaa!!!111");
+    }
+    op->pending_ops--;
+    if (op->pending_ops == 0)
+    {
+        
+    }
+}