Use mmap to read an extent from a datafile (#13834)

* Use MMAP to read an extent from the datafile. Fallback to uv_fs_read if that fails

* Schedule the fallback using uv_fs_read in the MMAP callback

* Check the return value of mmap correctly

* Add unlikely

1 files changed, 4 insertions, 0 deletions

diff --git a/database/engine/rrdengine.h b/database/engine/rrdengine.h
index 2bb70ddf53..fedadbe861 100644
--- a/database/engine/rrdengine.h
+++ b/database/engine/rrdengine.h
@@ -105,8 +105,12 @@ struct rrdeng_cmdqueue {
 
 struct extent_io_descriptor {
     uv_fs_t req;
+    uv_work_t req_worker;
     uv_buf_t iov;
+    uv_file file;
     void *buf;
+    void *map_base;
+    size_t map_length;
     uint64_t pos;
     unsigned bytes;
     struct completion *completion;