From 08262fc3e943dab8c6faa112dc313c9a245fce03 Mon Sep 17 00:00:00 2001
From: Astro <astro@spaceboyz.net>
Date: Sat, 12 Dec 2020 01:07:24 +0100
Subject: [PATCH] write_value(): take value_buf for serialization from outside

the caller should know the required size of that.
---
 src/lib.rs  |  9 ++++++---
 src/test.rs | 16 ++++++++--------
 2 files changed, 14 insertions(+), 11 deletions(-)

diff --git a/src/lib.rs b/src/lib.rs
index ffddbf9..7161408 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -186,9 +186,12 @@ impl<B: StoreBackend> Store<B> {
 
     /// encode with `postcard`, write at `key`
     #[cfg(feature = "postcard-values")]
-    pub fn write_value<T: Serialize>(&mut self, key: &str, value: &T) -> Result<(), Error<B::Error>> {
-        let mut buf = [0; 64];
-        let data = postcard::to_slice(value, &mut buf)
+    pub fn write_value<T, V>(&mut self, key: &str, value: &T, mut value_buf: V) -> Result<(), Error<B::Error>>
+    where
+        T: Serialize,
+        V: AsMut<[u8]>,
+    {
+        let data = postcard::to_slice(value, value_buf.as_mut())
             .map_err(Error::Encode)?;
         self.write(key, data)
     }
diff --git a/src/test.rs b/src/test.rs
index 2dd8036..d2d07e5 100644
--- a/src/test.rs
+++ b/src/test.rs
@@ -83,7 +83,7 @@ fn write_read_str_utf8() {
 #[cfg(feature = "postcard-values")]
 fn write_read_value_str() {
     let mut store = make_store();
-    store.write_value("foo", &"bar").unwrap();
+    store.write_value("foo", &"bar", [0; 4]).unwrap();
     assert_eq!(store.read_value("foo"), Ok(Some("bar")));
 }
 
@@ -91,7 +91,7 @@ fn write_read_value_str() {
 #[cfg(feature = "postcard-values")]
 fn write_read_value_u32() {
     let mut store = make_store();
-    store.write_value("foo", &42005u32).unwrap();
+    store.write_value("foo", &42005u32, [0; 4]).unwrap();
     assert_eq!(store.read_value("foo"), Ok(Some(42005u32)));
 }
 
@@ -99,7 +99,7 @@ fn write_read_value_u32() {
 #[cfg(feature = "postcard-values")]
 fn write_read_value_i64() {
     let mut store = make_store();
-    store.write_value("foo", &-99999999i64).unwrap();
+    store.write_value("foo", &-99999999i64, &mut [0; 8]).unwrap();
     assert_eq!(store.read_value("foo"), Ok(Some(-99999999i64)));
 }
 
@@ -107,7 +107,7 @@ fn write_read_value_i64() {
 #[cfg(feature = "postcard-values")]
 fn write_read_value_f32() {
     let mut store = make_store();
-    store.write_value("foo", &3.75e17f32).unwrap();
+    store.write_value("foo", &3.75e17f32, &mut [0; 4]).unwrap();
     assert_eq!(store.read_value("foo"), Ok(Some(3.75e17f32)));
 }
 
@@ -115,7 +115,7 @@ fn write_read_value_f32() {
 #[cfg(feature = "postcard-values")]
 fn write_read_value_f64() {
     let mut store = make_store();
-    store.write_value("foo", &-1.999e-13f64).unwrap();
+    store.write_value("foo", &-1.999e-13f64, [0; 8]).unwrap();
     assert_eq!(store.read_value("foo"), Ok(Some(-1.999e-13f64)));
 }
 
@@ -134,11 +134,11 @@ fn write_many() {
 #[cfg(feature = "postcard-values")]
 fn write_value_many() {
     let mut store = make_store();
-    store.write_value("quux", &(false, 3u8, -42i16)).unwrap();
+    store.write_value("quux", &(false, 3u8, -42i16), [0; 4]).unwrap();
     for i in 0..1000u32 {
-        store.write_value("bar", &i).unwrap();
+        store.write_value("bar", &i, [0; 4]).unwrap();
         assert_eq!(store.read_value("bar"), Ok(Some(i)));
-        store.write_value("foo", &(i % 2 == 0)).unwrap();
+        store.write_value("foo", &(i % 2 == 0), [0]).unwrap();
         assert_eq!(store.read_value("foo"), Ok(Some(i % 2 == 0)));
     }
     assert_eq!(store.read_value("quux"), Ok(Some((false, 3u8, -42i16))));