Merge #384

384: Replace memmap with memmap2 r=Kerollmops a=palfrey

[memmap is unmaintained](https://rustsec.org/advisories/RUSTSEC-2020-0077.html) and needs replacing. memmap2 is a drop-in replacement fork that's well maintained. Note that the version numbers got reset on fork, hence the lower values.

Co-authored-by: Tom Parker-Shemilt <palfrey@tevp.net>

milli/Cargo.toml

@@ -23,7 +23,7 @@ human_format = "1.0.3"
 levenshtein_automata = { version = "0.2.0", features = ["fst_automaton"] }
 linked-hash-map = "0.5.4"
 meilisearch-tokenizer = { git = "https://github.com/meilisearch/tokenizer.git", tag = "v0.2.5" }
-memmap = "0.7.0"
+memmap2 = "0.5.0"
 obkv = "0.2.0"
 once_cell = "1.5.2"
 ordered-float = "2.1.1"

milli/src/update/index_documents/helpers/clonable_mmap.rs

@@ -1,6 +1,6 @@
 use std::sync::Arc;
 
-use memmap::Mmap;
+use memmap2::Mmap;
 
 /// Wrapper around Mmap allowing to virtualy clone grenad-chunks
 /// in a parallel process like the indexing.

milli/src/update/index_documents/helpers/grenad_helpers.rs

@@ -70,7 +70,7 @@ pub unsafe fn into_clonable_grenad(
     reader: grenad::Reader<File>,
 ) -> Result<grenad::Reader<CursorClonableMmap>> {
     let file = reader.into_inner();
-    let mmap = memmap::Mmap::map(&file)?;
+    let mmap = memmap2::Mmap::map(&file)?;
     let cursor = io::Cursor::new(ClonableMmap::from(mmap));
     let reader = grenad::Reader::new(cursor)?;
     Ok(reader)