From e5caffb6acbe3436186ea348712c70d77181f7c1 Mon Sep 17 00:00:00 2001
From: Vitaliy Filippov <vitalif@yourcmc.ru>
Date: Sun, 10 Nov 2019 13:26:56 +0300
Subject: [PATCH] Allow to read specific versions

---
 blockstore.cpp      |  6 ++----
 blockstore.h        | 10 +++++-----
 blockstore_read.cpp |  3 +--
 3 files changed, 8 insertions(+), 11 deletions(-)

diff --git a/blockstore.cpp b/blockstore.cpp
index 6c301f0c..a99f1e3b 100644
--- a/blockstore.cpp
+++ b/blockstore.cpp
@@ -66,8 +66,7 @@ void blockstore::handle_event(ring_data_t *data)
     else
     {
         struct blockstore_operation* op = (struct blockstore_operation*)data->op;
-        if ((op->flags & OP_TYPE_MASK) == OP_READ_DIRTY ||
-            (op->flags & OP_TYPE_MASK) == OP_READ)
+        if ((op->flags & OP_TYPE_MASK) == OP_READ)
         {
             handle_read_event(data, op);
         }
@@ -145,8 +144,7 @@ void blockstore::loop()
             unsigned ring_space = io_uring_sq_space_left(ringloop->ring);
             unsigned prev_sqe_pos = ringloop->ring->sq.sqe_tail;
             int dequeue_op = 0;
-            if ((op->flags & OP_TYPE_MASK) == OP_READ_DIRTY ||
-                (op->flags & OP_TYPE_MASK) == OP_READ)
+            if ((op->flags & OP_TYPE_MASK) == OP_READ)
             {
                 dequeue_op = dequeue_read(op);
             }
diff --git a/blockstore.h b/blockstore.h
index 997b46c1..e8c59564 100644
--- a/blockstore.h
+++ b/blockstore.h
@@ -171,11 +171,10 @@ public:
 // In fact, adding a write operation must immediately result in dirty_db being populated
 
 #define OP_READ 1
-#define OP_READ_DIRTY 2
-#define OP_WRITE 3
-#define OP_SYNC 4
-#define OP_STABLE 5
-#define OP_DELETE 6
+#define OP_WRITE 2
+#define OP_SYNC 3
+#define OP_STABLE 4
+#define OP_DELETE 5
 #define OP_TYPE_MASK 0x7
 
 // Suspend operation until there are more free SQEs
@@ -192,6 +191,7 @@ struct blockstore_operation
     std::function<void (blockstore_operation*)> callback;
     uint32_t flags;
     object_id oid;
+    // For reads: version=0 -> last stable, version=UINT64_MAX -> last unstable, version=X -> specific version
     uint64_t version;
     uint32_t offset;
     uint32_t len;
diff --git a/blockstore_read.cpp b/blockstore_read.cpp
index 3552122a..124f5984 100644
--- a/blockstore_read.cpp
+++ b/blockstore_read.cpp
@@ -71,7 +71,6 @@ int blockstore::fulfill_read(blockstore_operation *read_op, uint32_t item_start,
 
 int blockstore::dequeue_read(blockstore_operation *read_op)
 {
-    // FIXME: allow to read specific version
     auto clean_it = object_db.find(read_op->oid);
     auto dirty_it = dirty_db.upper_bound((obj_ver_id){
         .oid = read_op->oid,
@@ -94,7 +93,7 @@ int blockstore::dequeue_read(blockstore_operation *read_op)
         while (dirty_it->first.oid == read_op->oid)
         {
             dirty_entry& dirty = dirty_it->second;
-            if ((read_op->flags & OP_TYPE_MASK) == OP_READ_DIRTY || IS_STABLE(dirty.state))
+            if (IS_STABLE(dirty.state) || read_op->version >= dirty_it->first.version)
             {
                 if (!fulfill_read(read_op, dirty.offset, dirty.offset + dirty.size,
                     dirty.state, dirty_it->first.version, dirty.location))