data_blob: add TODO comment for zstd api

we currently use the behavior of zstd that is not part of the public
api, so this is at risk to be changed without notice.

There is a public api that we could use, but it's only available
with zstd_sys >= 2.0.9, which at this time, is not yet packaged for/by
us.

Add a comment that we can use the public api for this when the
new version of the crate gets available.

Signed-off-by: Dominik Csapak <d.csapak@proxmox.com>

diff --git a/pbs-datastore/src/data_blob.rs b/pbs-datastore/src/data_blob.rs
index fd84f4be95e98832162063c2c69eceda4379ee09..0fb4d44c2af5f3c37ee65b9c98f1fe1c250e86fa 100644 (file)
--- a/pbs-datastore/src/data_blob.rs
+++ b/pbs-datastore/src/data_blob.rs
@@ -556,6 +556,8 @@ impl<'a, 'b> DataChunkBuilder<'a, 'b> {
 ///
 /// There is a test below to ensure we catch any change in the interface or internal value.
 fn zstd_error_is_target_too_small(err: usize) -> bool {
+    // TODO: when zstd_sys >= 2.0.9 is available, we can use
+    // ZSTD_getErrorCode and the enum to use the public zstd API
     let (real_code, _) = 0usize.overflowing_sub(err);
     // see ZSTD_ErrorCode in https://github.com/facebook/zstd/blob/dev/lib/zstd_errors.h
     real_code == 70 // ZSTD_error_dstSize_tooSmall