From f01eea07d36eab0cbbb4dce849c82f43fc83def1 Mon Sep 17 00:00:00 2001
From: Vitaliy Filippov <vitalif@yourcmc.ru>
Date: Sat, 13 Feb 2021 23:11:07 +0300
Subject: [PATCH] Add simplified interface to read blockstore bitmaps
 synchronously

---
 src/blockstore.cpp      |  5 +++++
 src/blockstore.h        |  3 +++
 src/blockstore_impl.h   |  3 +++
 src/blockstore_read.cpp | 47 +++++++++++++++++++++++++++++++++++++++++
 4 files changed, 58 insertions(+)

diff --git a/src/blockstore.cpp b/src/blockstore.cpp
index a73ed34b..e4a70f4c 100644
--- a/src/blockstore.cpp
+++ b/src/blockstore.cpp
@@ -38,6 +38,11 @@ void blockstore_t::enqueue_op(blockstore_op_t *op)
     impl->enqueue_op(op);
 }
 
+int blockstore_t::read_bitmap(object_id oid, uint64_t target_version, void *bitmap, uint64_t *result_version)
+{
+    return impl->read_bitmap(oid, target_version, bitmap, result_version);
+}
+
 std::unordered_map<object_id, uint64_t> & blockstore_t::get_unstable_writes()
 {
     return impl->unstable_writes;
diff --git a/src/blockstore.h b/src/blockstore.h
index 5acb73c8..8ce67097 100644
--- a/src/blockstore.h
+++ b/src/blockstore.h
@@ -179,6 +179,9 @@ public:
     // Submission
     void enqueue_op(blockstore_op_t *op);
 
+    // Simplified synchronous operation: get object bitmap & current version
+    int read_bitmap(object_id oid, uint64_t target_version, void *bitmap, uint64_t *result_version = NULL);
+
     // Unstable writes are added here (map of object_id -> version)
     std::unordered_map<object_id, uint64_t> & get_unstable_writes();
 
diff --git a/src/blockstore_impl.h b/src/blockstore_impl.h
index a9f39fb8..43b95f63 100644
--- a/src/blockstore_impl.h
+++ b/src/blockstore_impl.h
@@ -324,6 +324,9 @@ public:
     // Submission
     void enqueue_op(blockstore_op_t *op);
 
+    // Simplified synchronous operation: get object bitmap & current version
+    int read_bitmap(object_id oid, uint64_t target_version, void *bitmap, uint64_t *result_version = NULL);
+
     // Unstable writes are added here (map of object_id -> version)
     std::unordered_map<object_id, uint64_t> unstable_writes;
 
diff --git a/src/blockstore_read.cpp b/src/blockstore_read.cpp
index 78b4eb1c..ea599b0d 100644
--- a/src/blockstore_read.cpp
+++ b/src/blockstore_read.cpp
@@ -268,3 +268,50 @@ void blockstore_impl_t::handle_read_event(ring_data_t *data, blockstore_op_t *op
         FINISH_OP(op);
     }
 }
+
+int blockstore_impl_t::read_bitmap(object_id oid, uint64_t target_version, void *bitmap, uint64_t *result_version)
+{
+    auto dirty_it = dirty_db.upper_bound((obj_ver_id){
+        .oid = oid,
+        .version = UINT64_MAX,
+    });
+    if (dirty_it != dirty_db.begin())
+        dirty_it--;
+    if (dirty_it != dirty_db.end())
+    {
+        while (dirty_it->first.oid == oid)
+        {
+            if (target_version >= dirty_it->first.version)
+            {
+                if (result_version)
+                    *result_version = dirty_it->first.version;
+                if (bitmap)
+                {
+                    void *bmp_ptr = (clean_entry_bitmap_size > sizeof(void*) ? dirty_it->second.bitmap : &dirty_it->second.bitmap);
+                    memcpy(bitmap, bmp_ptr, clean_entry_bitmap_size);
+                }
+                return 0;
+            }
+            if (dirty_it == dirty_db.begin())
+                break;
+            dirty_it--;
+        }
+    }
+    auto clean_it = clean_db.find(oid);
+    if (clean_it != clean_db.end())
+    {
+        if (result_version)
+            *result_version = clean_it->second.version;
+        if (bitmap)
+        {
+            void *bmp_ptr = get_clean_entry_bitmap(clean_it->second.location, clean_entry_bitmap_size);
+            memcpy(bitmap, bmp_ptr, clean_entry_bitmap_size);
+        }
+        return 0;
+    }
+    if (result_version)
+        *result_version = 0;
+    if (bitmap)
+        memset(bitmap, 0, clean_entry_bitmap_size);
+    return -ENOENT;
+}