server: use etag for vecs instead of date modified

crates/brk_vec/src/traits/any.rs

@@ -1,6 +1,4 @@
-use std::time::Duration;
-
-use brk_core::{Result, Version};
+use brk_core::Version;
 
 use super::{BoxedVecIterator, StoredIndex, StoredType};
 
@@ -11,9 +9,23 @@ pub trait AnyVec: Send + Sync {
     fn is_empty(&self) -> bool {
         self.len() == 0
     }
-    fn modified_time(&self) -> Result<Duration>;
     fn index_type_to_string(&self) -> &'static str;
     fn value_type_to_size_of(&self) -> usize;
+    fn etag(&self, to: Option<i64>) -> String {
+        let len = self.len();
+        format!(
+            "{}-{:?}",
+            to.map_or(len, |to| {
+                if to.is_negative() {
+                    len.checked_sub(to.unsigned_abs() as usize)
+                        .unwrap_or_default()
+                } else {
+                    to as usize
+                }
+            }),
+            self.version()
+        )
+    }
 }
 
 pub trait AnyIterableVec<I, T>: AnyVec {

crates/brk_vec/src/traits/generic.rs

@@ -3,7 +3,6 @@ use std::{
     io::{self, Seek, SeekFrom, Write},
     path::{Path, PathBuf},
     sync::Arc,
-    time::{self, Duration},
 };
 
 use arc_swap::ArcSwap;
@@ -168,12 +167,4 @@ where
     fn flush(&mut self) -> Result<()>;
 
     fn truncate_if_needed(&mut self, index: I) -> Result<()>;
-
-    fn modified_time_(&self) -> Result<Duration> {
-        Ok(self
-            .file()
-            .metadata()?
-            .modified()?
-            .duration_since(time::UNIX_EPOCH)?)
-    }
 }

crates/brk_vec/src/variants/compressed.rs

@@ -3,7 +3,6 @@ use std::{
     mem,
     path::{Path, PathBuf},
     sync::Arc,
-    time::Duration,
 };
 
 use arc_swap::{ArcSwap, Guard};
@@ -381,11 +380,6 @@ where
         self.len_()
     }
 
-    #[inline]
-    fn modified_time(&self) -> Result<Duration> {
-        self.modified_time_()
-    }
-
     #[inline]
     fn index_type_to_string(&self) -> &'static str {
         I::to_string()

crates/brk_vec/src/variants/computed.rs

@@ -1,4 +1,4 @@
-use std::{fs, path::Path, time::Duration};
+use std::{fs, path::Path};
 
 use brk_exit::Exit;
 use clap_derive::ValueEnum;
@@ -245,15 +245,6 @@ where
         }
     }
 
-    fn modified_time(&self) -> Result<Duration> {
-        match self {
-            ComputedVec::Eager { vec, .. } => vec.modified_time(),
-            ComputedVec::LazyFrom1(v) => v.modified_time(),
-            ComputedVec::LazyFrom2(v) => v.modified_time(),
-            ComputedVec::LazyFrom3(v) => v.modified_time(),
-        }
-    }
-
     #[inline]
     fn value_type_to_size_of(&self) -> usize {
         size_of::<T>()

crates/brk_vec/src/variants/eager.rs

@@ -5,7 +5,6 @@ use std::{
     fmt::Debug,
     ops::{Add, Div, Mul},
     path::{Path, PathBuf},
-    time::Duration,
 };
 
 use arc_swap::ArcSwap;
@@ -1304,11 +1303,6 @@ where
         self.0.len()
     }
 
-    #[inline]
-    fn modified_time(&self) -> Result<Duration> {
-        self.0.modified_time()
-    }
-
     #[inline]
     fn index_type_to_string(&self) -> &'static str {
         I::to_string()

crates/brk_vec/src/variants/indexed.rs

@@ -1,4 +1,4 @@
-use std::{cmp::Ordering, fmt::Debug, path::Path, time::Duration};
+use std::{cmp::Ordering, fmt::Debug, path::Path};
 
 use arc_swap::ArcSwap;
 use brk_core::{Error, Height, Result, Value, Version};
@@ -103,11 +103,6 @@ where
         self.0.len()
     }
 
-    #[inline]
-    fn modified_time(&self) -> Result<Duration> {
-        self.0.modified_time()
-    }
-
     #[inline]
     fn index_type_to_string(&self) -> &'static str {
         I::to_string()

crates/brk_vec/src/variants/lazy1.rs

@@ -143,10 +143,6 @@ where
         self.source.len()
     }
 
-    fn modified_time(&self) -> Result<std::time::Duration> {
-        self.source.modified_time()
-    }
-
     #[inline]
     fn value_type_to_size_of(&self) -> usize {
         size_of::<T>()

crates/brk_vec/src/variants/lazy2.rs

@@ -188,13 +188,6 @@ where
         len1.min(len2)
     }
 
-    fn modified_time(&self) -> Result<std::time::Duration> {
-        Ok(self
-            .source1
-            .modified_time()?
-            .min(self.source2.modified_time()?))
-    }
-
     #[inline]
     fn value_type_to_size_of(&self) -> usize {
         size_of::<T>()

crates/brk_vec/src/variants/lazy3.rs

@@ -222,14 +222,6 @@ where
         len1.min(len2).min(len3)
     }
 
-    fn modified_time(&self) -> Result<std::time::Duration> {
-        Ok(self
-            .source1
-            .modified_time()?
-            .min(self.source2.modified_time()?)
-            .min(self.source3.modified_time()?))
-    }
-
     #[inline]
     fn value_type_to_size_of(&self) -> usize {
         size_of::<T>()

crates/brk_vec/src/variants/raw.rs

@@ -5,7 +5,6 @@ use std::{
     mem,
     path::{Path, PathBuf},
     sync::Arc,
-    time::Duration,
 };
 
 use arc_swap::{ArcSwap, Guard};
@@ -250,11 +249,6 @@ where
         self.len_()
     }
 
-    #[inline]
-    fn modified_time(&self) -> Result<Duration> {
-        self.modified_time_()
-    }
-
     #[inline]
     fn index_type_to_string(&self) -> &'static str {
         I::to_string()

crates/brk_vec/src/variants/stored.rs

@@ -1,7 +1,6 @@
 use std::{
     fs::File,
     path::{Path, PathBuf},
-    time::Duration,
 };
 
 use arc_swap::ArcSwap;
@@ -191,14 +190,6 @@ where
         self.pushed_len() + self.stored_len()
     }
 
-    #[inline]
-    fn modified_time(&self) -> Result<Duration> {
-        match self {
-            StoredVec::Raw(v) => v.modified_time(),
-            StoredVec::Compressed(v) => v.modified_time(),
-        }
-    }
-
     fn name(&self) -> &str {
         match self {
             StoredVec::Raw(v) => v.name(),