vec: rework part 1

crates/brk_vec/src/enums/error.rs

@@ -15,6 +15,7 @@ pub enum Error {
     IO(io::Error),
     ZeroCopyError,
     IndexTooHigh,
+    EmptyVec,
     IndexTooLow,
     ExpectFileToHaveIndex,
     ExpectVecToHaveIndex,
@@ -68,6 +69,7 @@ impl fmt::Display for Error {
             Error::ZeroCopyError => write!(f, "Zero copy convert error"),
             Error::RangeFromAfterTo(from, to) => write!(f, "Range, from {from} is after to {to}"),
             Error::DifferentCompressionMode => write!(f, "Different compression mode chosen"),
+            Error::EmptyVec => write!(f, "The Vec is empty, maybe wait for a bit"),
         }
     }
 }

crates/brk_vec/src/enums/values.rs

@@ -3,7 +3,10 @@ use std::ops::Range;
 use memmap2::Mmap;
 use zerocopy::{Immutable, IntoBytes, KnownLayout, TryFromBytes};
 
-use crate::MAX_PAGE_SIZE;
+const ONE_KIB: usize = 1024;
+pub const MAX_PAGE_SIZE: usize = 16 * ONE_KIB;
+const ONE_MIB: usize = ONE_KIB * ONE_KIB;
+pub const MAX_CACHE_SIZE: usize = 100 * ONE_MIB;
 
 use super::Result;