Make read_i64_from private and merge read_str_from to its caller

Also remove duplicated read_i64_from.

Signed-off-by: Tim Zhang <tim@hyper.sh>

src/memory.rs

@@ -17,6 +17,7 @@ use std::sync::mpsc::Receiver;
 use crate::error::ErrorKind::*;
 use crate::error::*;
 use crate::events;
+use crate::read_i64_from;
 
 use crate::flat_keyed_to_hashmap;
 
@@ -880,17 +881,6 @@ fn read_u64_from(mut file: File) -> Result<u64> {
     }
 }
 
-fn read_i64_from(mut file: File) -> Result<i64> {
-    let mut string = String::new();
-    match file.read_to_string(&mut string) {
-        Ok(_) => string
-            .trim()
-            .parse()
-            .map_err(|e| Error::with_cause(ParseError, e)),
-        Err(e) => Err(Error::with_cause(ReadFailed, e)),
-    }
-}
-
 fn read_string_from(mut file: File) -> Result<String> {
     let mut string = String::new();
     match file.read_to_string(&mut string) {