[#41] object: Support erasure codes

Signed-off-by: Evgenii Stratonikov <e.stratonikov@yadro.com>

object/service.proto

@@ -319,6 +319,9 @@ message GetResponse {
 
       // Meta information of split hierarchy for object assembly.
       SplitInfo split_info = 3;
+
+      // Meta information for EC object assembly.
+      ECInfo ec_info = 4;
     }
   }
   // Body of get object response message.
@@ -503,6 +506,9 @@ message HeadResponse {
 
       // Meta information of split hierarchy.
       SplitInfo split_info = 3;
+
+      // Meta information for EC object assembly.
+      ECInfo ec_info = 4;
     }
   }
   // Body of head object response message.
@@ -678,6 +684,9 @@ message GetRangeResponse {
 
       // Meta information of split hierarchy.
       SplitInfo split_info = 2;
+
+      // Meta information for EC object assembly.
+      ECInfo ec_info = 3;
     }
   }
 

object/types.proto

@@ -193,6 +193,24 @@ message Header {
   }
   // Position of the object in the split hierarchy
   Split split = 11 [ json_name = "split" ];
+
+  // Erasure code can be applied to any object.
+  // Information about encoded object structure is stored in `EC` header.
+  // All objects belonging to a single EC group have the same `parent` field.
+  message EC {
+    // Identifier of the origin object. Known to all chunks.
+    neo.fs.v2.refs.ObjectID parent = 1 [ json_name = "parent" ];
+    // Index of this chunk.
+    uint32 index = 2 [ json_name = "index" ];
+    // Total number of chunks in this split.
+    uint32 total = 3 [ json_name = "total" ];
+    // Total length of a parent header. Used to trim padding zeroes.
+    uint32 header_length = 4 [ json_name = "headerLength" ];
+    // Chunk of a parent header.
+    bytes header = 5 [ json_name = "header" ];
+  }
+  // Erasure code chunk information.
+  EC ec = 12 [ json_name = "ec" ];
 }
 
 // Object structure. Object is immutable and content-addressed. It means
@@ -232,3 +250,17 @@ message SplitInfo {
   // object parts.
   neo.fs.v2.refs.ObjectID link = 3;
 }
+
+// Meta information for the erasure-encoded object.
+message ECInfo {
+  message Chunk {
+    // Object ID of the chunk.
+    neo.fs.v2.refs.ObjectID id = 1;
+    // Index of the chunk.
+    uint32 index = 2;
+    // Total number of chunks in this split.
+    uint32 total = 3;
+  }
+  // Chunk stored on the node.
+  repeated Chunk chunks = 1;
+}