CDRIVER-2418 send readConcern only with read cmds

Author: ajdavis

src/mongoc/mongoc-client.c

@@ -1729,6 +1729,7 @@ _mongoc_client_command_with_opts (mongoc_client_t *client,
    BSON_ASSERT (command);
 
    mongoc_cmd_parts_init (&parts, client, db_name, flags, command);
+   parts.is_read_command = (mode & MONGOC_CMD_READ);
    parts.is_write_command = (mode & MONGOC_CMD_WRITE);
 
    reply_ptr = reply ? reply : &reply_local;

src/mongoc/mongoc-cmd-private.h

@@ -66,6 +66,7 @@ typedef struct _mongoc_cmd_parts_t {
    bson_t extra;
    const mongoc_read_prefs_t *read_prefs;
    bson_t assembled_body;
+   bool is_read_command;
    bool is_write_command;
    bool prohibit_lsid;
    mongoc_cmd_parts_allow_txn_number_t allow_txn_number;

src/mongoc/mongoc-cmd.c

@@ -34,6 +34,7 @@ mongoc_cmd_parts_init (mongoc_cmd_parts_t *parts,
    parts->body = command_body;
    parts->user_query_flags = user_query_flags;
    parts->read_prefs = NULL;
+   parts->is_read_command = false;
    parts->is_write_command = false;
    parts->prohibit_lsid = false;
    parts->allow_txn_number = MONGOC_CMD_PARTS_ALLOW_TXN_NUMBER_UNKNOWN;
@@ -654,7 +655,7 @@ mongoc_cmd_parts_assemble (mongoc_cmd_parts_t *parts,
             &parts->assembled_body, "$clusterTime", 12, cluster_time);
       }
 
-      if (!is_get_more) {
+      if (parts->is_read_command && !is_get_more) {
          /* This condition should never trigger for an implicit client session.
           * Even though the causal consistency option may default to true, an
           * implicit client session will have no previous operation time. */

src/mongoc/mongoc-collection.c

@@ -2949,6 +2949,7 @@ mongoc_collection_find_and_modify_with_opts (
 
    mongoc_cmd_parts_init (
       &parts, collection->client, collection->db, MONGOC_QUERY_NONE, &command);
+   parts.is_read_command = true;
    parts.is_write_command = true;
 
    if (bson_iter_init (&iter, &opts->extra)) {
@@ -2989,8 +2990,9 @@ mongoc_collection_find_and_modify_with_opts (
     * a new writable stream and retry. If server selection fails or the selected
     * server does not support retryable writes, fall through and allow the
     * original error to be reported. */
-   if (!ret && is_retryable && (error->domain == MONGOC_ERROR_STREAM ||
-                                mongoc_cluster_is_not_master_error (error))) {
+   if (!ret && is_retryable &&
+       (error->domain == MONGOC_ERROR_STREAM ||
+        mongoc_cluster_is_not_master_error (error))) {
       bson_error_t ignored_error;
 
       /* each write command may be retried at most once */
@@ -3003,9 +3005,8 @@ mongoc_collection_find_and_modify_with_opts (
       retry_server_stream =
          mongoc_cluster_stream_for_writes (cluster, &ignored_error);
 
-      if (retry_server_stream &&
-          retry_server_stream->sd->max_wire_version >=
-             WIRE_VERSION_RETRY_WRITES) {
+      if (retry_server_stream && retry_server_stream->sd->max_wire_version >=
+                                    WIRE_VERSION_RETRY_WRITES) {
          parts.assembled.server_stream = retry_server_stream;
          GOTO (retry);
       }

src/mongoc/mongoc-cursor.c

@@ -1313,6 +1313,7 @@ _mongoc_cursor_run_command (mongoc_cursor_t *cursor,
    cluster = &cursor->client->cluster;
    mongoc_cmd_parts_init (
       &parts, cursor->client, db, MONGOC_QUERY_NONE, command);
+   parts.is_read_command = true;
    parts.read_prefs = cursor->read_prefs;
    parts.assembled.operation_id = cursor->operation_id;
    server_stream = _mongoc_cursor_fetch_stream (cursor);