CDRIVER-4722 remove cursor support for legacy opcodes (#2112)

Author: connorsmacd

src/libmongoc/CMakeLists.txt

@@ -568,9 +568,6 @@ set (MONGOC_SOURCES
    ${PROJECT_SOURCE_DIR}/src/mongoc/mongoc-cursor-change-stream.c
    ${PROJECT_SOURCE_DIR}/src/mongoc/mongoc-cursor-cmd-deprecated.c
    ${PROJECT_SOURCE_DIR}/src/mongoc/mongoc-cursor-find.c
-   ${PROJECT_SOURCE_DIR}/src/mongoc/mongoc-cursor-find-cmd.c
-   ${PROJECT_SOURCE_DIR}/src/mongoc/mongoc-cursor-find-opquery.c
-   ${PROJECT_SOURCE_DIR}/src/mongoc/mongoc-cursor-legacy.c
    ${PROJECT_SOURCE_DIR}/src/mongoc/mongoc-cursor-array.c
    ${PROJECT_SOURCE_DIR}/src/mongoc/mongoc-database.c
    ${PROJECT_SOURCE_DIR}/src/mongoc/mongoc-error.c

src/libmongoc/src/mongoc/mongoc-cursor-cmd.c

@@ -19,52 +19,12 @@
 
 #include <mongoc/mongoc.h>
 
-typedef enum { NONE, CMD_RESPONSE, OP_GETMORE_RESPONSE } reading_from_t;
-typedef enum { UNKNOWN, GETMORE_CMD, OP_GETMORE } getmore_type_t;
 typedef struct _data_cmd_t {
-   /* Two paths:
-    * - Mongo 3.2+, sent "getMore" cmd, we're reading reply's "nextBatch" array
-    * - Mongo 2.6 to 3, after "aggregate" or similar command we sent OP_GETMORE,
-    *   we're reading the raw reply from a stream
-    */
    mongoc_cursor_response_t response;
-   mongoc_cursor_response_legacy_t response_legacy;
-   reading_from_t reading_from;
-   getmore_type_t getmore_type; /* cache after first getmore. */
    bson_t cmd;
 } data_cmd_t;
 
 
-static getmore_type_t
-_getmore_type(mongoc_cursor_t *cursor)
-{
-   mongoc_server_stream_t *server_stream;
-   int32_t wire_version;
-   data_cmd_t *data = (data_cmd_t *)cursor->impl.data;
-   if (data->getmore_type != UNKNOWN) {
-      return data->getmore_type;
-   }
-   const mongoc_ss_log_context_t ss_log_context = {
-      .operation = "getMore", .has_operation_id = true, .operation_id = cursor->operation_id};
-   server_stream = _mongoc_cursor_fetch_stream(cursor, &ss_log_context);
-   if (!server_stream) {
-      return UNKNOWN;
-   }
-   wire_version = server_stream->sd->max_wire_version;
-   mongoc_server_stream_cleanup(server_stream);
-
-   // CDRIVER-4722: always GETMORE_CMD once WIRE_VERSION_MIN >=
-   // WIRE_VERSION_4_2.
-   if (_mongoc_cursor_use_op_msg(cursor, wire_version)) {
-      data->getmore_type = GETMORE_CMD;
-   } else {
-      data->getmore_type = OP_GETMORE;
-   }
-
-   return data->getmore_type;
-}
-
-
 static mongoc_cursor_state_t
 _prime(mongoc_cursor_t *cursor)
 {
@@ -79,7 +39,6 @@ _prime(mongoc_cursor_t *cursor)
    /* server replies to aggregate/listIndexes/listCollections with:
     * {cursor: {id: N, firstBatch: []}} */
    _mongoc_cursor_response_refresh(cursor, &data->cmd, &copied_opts, &data->response);
-   data->reading_from = CMD_RESPONSE;
    bson_destroy(&copied_opts);
    return IN_BATCH;
 }
@@ -90,18 +49,8 @@ _pop_from_batch(mongoc_cursor_t *cursor)
 {
    data_cmd_t *data = (data_cmd_t *)cursor->impl.data;
 
-   switch (data->reading_from) {
-   case CMD_RESPONSE:
-      _mongoc_cursor_response_read(cursor, &data->response, &cursor->current);
-      break;
-   case OP_GETMORE_RESPONSE:
-      cursor->current = bson_reader_read(data->response_legacy.reader, NULL);
-      break;
-   case NONE:
-   default:
-      fprintf(stderr, "trying to pop from an uninitialized cursor reader.\n");
-      BSON_ASSERT(false);
-   }
+   _mongoc_cursor_response_read(cursor, &data->response, &cursor->current);
+
    if (cursor->current) {
       return IN_BATCH;
    } else {
@@ -115,23 +64,12 @@ _get_next_batch(mongoc_cursor_t *cursor)
 {
    data_cmd_t *data = (data_cmd_t *)cursor->impl.data;
    bson_t getmore_cmd;
-   getmore_type_t getmore_type = _getmore_type(cursor);
-
-   switch (getmore_type) {
-   case GETMORE_CMD:
-      _mongoc_cursor_prepare_getmore_command(cursor, &getmore_cmd);
-      _mongoc_cursor_response_refresh(cursor, &getmore_cmd, NULL /* opts */, &data->response);
-      bson_destroy(&getmore_cmd);
-      data->reading_from = CMD_RESPONSE;
-      return IN_BATCH;
-   case OP_GETMORE:
-      _mongoc_cursor_op_getmore(cursor, &data->response_legacy);
-      data->reading_from = OP_GETMORE_RESPONSE;
-      return IN_BATCH;
-   case UNKNOWN:
-   default:
-      return DONE;
-   }
+
+   _mongoc_cursor_prepare_getmore_command(cursor, &getmore_cmd);
+   _mongoc_cursor_response_refresh(cursor, &getmore_cmd, NULL /* opts */, &data->response);
+   bson_destroy(&getmore_cmd);
+
+   return IN_BATCH;
 }
 
 
@@ -141,7 +79,6 @@ _destroy(mongoc_cursor_impl_t *impl)
    data_cmd_t *data = (data_cmd_t *)impl->data;
    bson_destroy(&data->response.reply);
    bson_destroy(&data->cmd);
-   _mongoc_cursor_response_legacy_destroy(&data->response_legacy);
    bson_free(data);
 }
 
@@ -152,7 +89,6 @@ _clone(mongoc_cursor_impl_t *dst, const mongoc_cursor_impl_t *src)
    data_cmd_t *data_src = (data_cmd_t *)src->data;
    data_cmd_t *data_dst = BSON_ALIGNED_ALLOC0(data_cmd_t);
    bson_init(&data_dst->response.reply);
-   _mongoc_cursor_response_legacy_init(&data_dst->response_legacy);
    bson_copy_to(&data_src->cmd, &data_dst->cmd);
    dst->data = data_dst;
 }
@@ -173,7 +109,6 @@ _mongoc_cursor_cmd_new(mongoc_client_t *client,
    data_cmd_t *data = BSON_ALIGNED_ALLOC0(data_cmd_t);
 
    cursor = _mongoc_cursor_new_with_opts(client, db_and_coll, opts, user_prefs, default_prefs, read_concern);
-   _mongoc_cursor_response_legacy_init(&data->response_legacy);
    _mongoc_cursor_check_and_copy_to(cursor, "command", cmd, &data->cmd);
    bson_init(&data->response.reply);
    cursor->impl.prime = _prime;
@@ -194,7 +129,6 @@ _mongoc_cursor_cmd_new_from_reply(mongoc_client_t *client, const bson_t *cmd, co
    mongoc_cursor_t *cursor = _mongoc_cursor_cmd_new(client, NULL, cmd, opts, NULL, NULL, NULL);
    data_cmd_t *data = (data_cmd_t *)cursor->impl.data;
 
-   data->reading_from = CMD_RESPONSE;
    cursor->state = IN_BATCH;
 
    bson_destroy(&data->response.reply);