aconfig: sort items in cache by name
Introduce a builder pattern for constructing a cache from flag
declarations and flag values. Teach the builder to sort the flags by
name as the last step. This will ensure consistent dump output
regardless of the order flags are specified in the input files.
Bug: 279485059
Test: atest aconfig.test
Change-Id: Icdd62f51fa3761a469663f17581a83d9909e9ffe
diff --git a/tools/aconfig/src/cache.rs b/tools/aconfig/src/cache.rs
index c546f7b..30810fa 100644
--- a/tools/aconfig/src/cache.rs
+++ b/tools/aconfig/src/cache.rs
@@ -51,72 +51,42 @@
items: Vec<Item>,
}
-impl Cache {
- pub fn new(namespace: String) -> Result<Cache> {
- ensure!(!namespace.is_empty(), "empty namespace");
- Ok(Cache { namespace, items: vec![] })
+// TODO: replace this function with Iterator.is_sorted_by_key(...)) when that API becomes stable
+fn iter_is_sorted_by_key<'a, T: 'a, F, K>(iter: impl Iterator<Item = &'a T>, f: F) -> bool
+where
+ F: FnMut(&'a T) -> K,
+ K: PartialOrd<K>,
+{
+ let mut last: Option<K> = None;
+ for current in iter.map(f) {
+ if let Some(l) = last {
+ if l > current {
+ return false;
+ }
+ }
+ last = Some(current);
}
+ true
+}
+impl Cache {
pub fn read_from_reader(reader: impl Read) -> Result<Cache> {
- serde_json::from_reader(reader).map_err(|e| e.into())
+ let cache: Cache = serde_json::from_reader(reader)?;
+ ensure!(
+ iter_is_sorted_by_key(cache.iter(), |item| &item.name),
+ "internal error: flags in cache file not sorted"
+ );
+ Ok(cache)
}
pub fn write_to_writer(&self, writer: impl Write) -> Result<()> {
+ ensure!(
+ iter_is_sorted_by_key(self.iter(), |item| &item.name),
+ "internal error: flags in cache file not sorted"
+ );
serde_json::to_writer(writer, self).map_err(|e| e.into())
}
- pub fn add_flag_declaration(
- &mut self,
- source: Source,
- declaration: FlagDeclaration,
- ) -> Result<()> {
- ensure!(!declaration.name.is_empty(), "empty flag name");
- ensure!(!declaration.description.is_empty(), "empty flag description");
- ensure!(
- self.items.iter().all(|item| item.name != declaration.name),
- "failed to declare flag {} from {}: flag already declared",
- declaration.name,
- source
- );
- self.items.push(Item {
- namespace: self.namespace.clone(),
- name: declaration.name.clone(),
- description: declaration.description,
- state: DEFAULT_FLAG_STATE,
- permission: DEFAULT_FLAG_PERMISSION,
- trace: vec![Tracepoint {
- source,
- state: DEFAULT_FLAG_STATE,
- permission: DEFAULT_FLAG_PERMISSION,
- }],
- });
- Ok(())
- }
-
- pub fn add_flag_value(&mut self, source: Source, value: FlagValue) -> Result<()> {
- ensure!(!value.namespace.is_empty(), "empty flag namespace");
- ensure!(!value.name.is_empty(), "empty flag name");
- ensure!(
- value.namespace == self.namespace,
- "failed to set values for flag {}/{} from {}: expected namespace {}",
- value.namespace,
- value.name,
- source,
- self.namespace
- );
- let Some(existing_item) = self.items.iter_mut().find(|item| item.name == value.name) else {
- bail!("failed to set values for flag {}/{} from {}: flag not declared", value.namespace, value.name, source);
- };
- existing_item.state = value.state;
- existing_item.permission = value.permission;
- existing_item.trace.push(Tracepoint {
- source,
- state: value.state,
- permission: value.permission,
- });
- Ok(())
- }
-
pub fn iter(&self) -> impl Iterator<Item = &Item> {
self.items.iter()
}
@@ -131,6 +101,80 @@
}
}
+#[derive(Debug)]
+pub struct CacheBuilder {
+ cache: Cache,
+}
+
+impl CacheBuilder {
+ pub fn new(namespace: String) -> Result<CacheBuilder> {
+ ensure!(!namespace.is_empty(), "empty namespace");
+ let cache = Cache { namespace, items: vec![] };
+ Ok(CacheBuilder { cache })
+ }
+
+ pub fn add_flag_declaration(
+ &mut self,
+ source: Source,
+ declaration: FlagDeclaration,
+ ) -> Result<&mut CacheBuilder> {
+ ensure!(!declaration.name.is_empty(), "empty flag name");
+ ensure!(!declaration.description.is_empty(), "empty flag description");
+ ensure!(
+ self.cache.items.iter().all(|item| item.name != declaration.name),
+ "failed to declare flag {} from {}: flag already declared",
+ declaration.name,
+ source
+ );
+ self.cache.items.push(Item {
+ namespace: self.cache.namespace.clone(),
+ name: declaration.name.clone(),
+ description: declaration.description,
+ state: DEFAULT_FLAG_STATE,
+ permission: DEFAULT_FLAG_PERMISSION,
+ trace: vec![Tracepoint {
+ source,
+ state: DEFAULT_FLAG_STATE,
+ permission: DEFAULT_FLAG_PERMISSION,
+ }],
+ });
+ Ok(self)
+ }
+
+ pub fn add_flag_value(
+ &mut self,
+ source: Source,
+ value: FlagValue,
+ ) -> Result<&mut CacheBuilder> {
+ ensure!(!value.namespace.is_empty(), "empty flag namespace");
+ ensure!(!value.name.is_empty(), "empty flag name");
+ ensure!(
+ value.namespace == self.cache.namespace,
+ "failed to set values for flag {}/{} from {}: expected namespace {}",
+ value.namespace,
+ value.name,
+ source,
+ self.cache.namespace
+ );
+ let Some(existing_item) = self.cache.items.iter_mut().find(|item| item.name == value.name) else {
+ bail!("failed to set values for flag {}/{} from {}: flag not declared", value.namespace, value.name, source);
+ };
+ existing_item.state = value.state;
+ existing_item.permission = value.permission;
+ existing_item.trace.push(Tracepoint {
+ source,
+ state: value.state,
+ permission: value.permission,
+ });
+ Ok(self)
+ }
+
+ pub fn build(mut self) -> Cache {
+ self.cache.items.sort_by_cached_key(|item| item.name.clone());
+ self.cache
+ }
+}
+
#[cfg(test)]
mod tests {
use super::*;
@@ -138,14 +182,14 @@
#[test]
fn test_add_flag_declaration() {
- let mut cache = Cache::new("ns".to_string()).unwrap();
- cache
+ let mut builder = CacheBuilder::new("ns".to_string()).unwrap();
+ builder
.add_flag_declaration(
Source::File("first.txt".to_string()),
FlagDeclaration { name: "foo".to_string(), description: "desc".to_string() },
)
.unwrap();
- let error = cache
+ let error = builder
.add_flag_declaration(
Source::File("second.txt".to_string()),
FlagDeclaration { name: "foo".to_string(), description: "desc".to_string() },
@@ -155,17 +199,26 @@
&format!("{:?}", error),
"failed to declare flag foo from second.txt: flag already declared"
);
+ builder
+ .add_flag_declaration(
+ Source::File("first.txt".to_string()),
+ FlagDeclaration { name: "bar".to_string(), description: "desc".to_string() },
+ )
+ .unwrap();
+
+ let cache = builder.build();
+
+ // check flags are sorted by name
+ assert_eq!(
+ cache.into_iter().map(|item| item.name).collect::<Vec<_>>(),
+ vec!["bar".to_string(), "foo".to_string()]
+ );
}
#[test]
fn test_add_flag_value() {
- fn check(cache: &Cache, name: &str, expected: (FlagState, Permission)) -> bool {
- let item = cache.iter().find(|&item| item.name == name).unwrap();
- item.state == expected.0 && item.permission == expected.1
- }
-
- let mut cache = Cache::new("ns".to_string()).unwrap();
- let error = cache
+ let mut builder = CacheBuilder::new("ns".to_string()).unwrap();
+ let error = builder
.add_flag_value(
Source::Memory,
FlagValue {
@@ -181,15 +234,14 @@
"failed to set values for flag ns/foo from <memory>: flag not declared"
);
- cache
+ builder
.add_flag_declaration(
Source::File("first.txt".to_string()),
FlagDeclaration { name: "foo".to_string(), description: "desc".to_string() },
)
.unwrap();
- assert!(check(&cache, "foo", (DEFAULT_FLAG_STATE, DEFAULT_FLAG_PERMISSION)));
- cache
+ builder
.add_flag_value(
Source::Memory,
FlagValue {
@@ -200,9 +252,8 @@
},
)
.unwrap();
- assert!(check(&cache, "foo", (FlagState::Disabled, Permission::ReadOnly)));
- cache
+ builder
.add_flag_value(
Source::Memory,
FlagValue {
@@ -213,10 +264,9 @@
},
)
.unwrap();
- assert!(check(&cache, "foo", (FlagState::Enabled, Permission::ReadWrite)));
// different namespace -> no-op
- let error = cache
+ let error = builder
.add_flag_value(
Source::Memory,
FlagValue {
@@ -228,19 +278,23 @@
)
.unwrap_err();
assert_eq!(&format!("{:?}", error), "failed to set values for flag some-other-namespace/foo from <memory>: expected namespace ns");
- assert!(check(&cache, "foo", (FlagState::Enabled, Permission::ReadWrite)));
+
+ let cache = builder.build();
+ let item = cache.iter().find(|&item| item.name == "foo").unwrap();
+ assert_eq!(FlagState::Enabled, item.state);
+ assert_eq!(Permission::ReadWrite, item.permission);
}
#[test]
fn test_reject_empty_cache_namespace() {
- Cache::new("".to_string()).unwrap_err();
+ CacheBuilder::new("".to_string()).unwrap_err();
}
#[test]
fn test_reject_empty_flag_declaration_fields() {
- let mut cache = Cache::new("ns".to_string()).unwrap();
+ let mut builder = CacheBuilder::new("ns".to_string()).unwrap();
- let error = cache
+ let error = builder
.add_flag_declaration(
Source::Memory,
FlagDeclaration { name: "".to_string(), description: "Description".to_string() },
@@ -248,7 +302,7 @@
.unwrap_err();
assert_eq!(&format!("{:?}", error), "empty flag name");
- let error = cache
+ let error = builder
.add_flag_declaration(
Source::Memory,
FlagDeclaration { name: "foo".to_string(), description: "".to_string() },
@@ -259,15 +313,15 @@
#[test]
fn test_reject_empty_flag_value_files() {
- let mut cache = Cache::new("ns".to_string()).unwrap();
- cache
+ let mut builder = CacheBuilder::new("ns".to_string()).unwrap();
+ builder
.add_flag_declaration(
Source::Memory,
FlagDeclaration { name: "foo".to_string(), description: "desc".to_string() },
)
.unwrap();
- let error = cache
+ let error = builder
.add_flag_value(
Source::Memory,
FlagValue {
@@ -280,7 +334,7 @@
.unwrap_err();
assert_eq!(&format!("{:?}", error), "empty flag namespace");
- let error = cache
+ let error = builder
.add_flag_value(
Source::Memory,
FlagValue {
@@ -293,4 +347,11 @@
.unwrap_err();
assert_eq!(&format!("{:?}", error), "empty flag name");
}
+
+ #[test]
+ fn test_iter_is_sorted_by_key() {
+ assert!(iter_is_sorted_by_key(["a", "b", "c"].iter(), |s| s));
+ assert!(iter_is_sorted_by_key(Vec::<&str>::new().iter(), |s| s));
+ assert!(!iter_is_sorted_by_key(["a", "c", "b"].iter(), |s| s));
+ }
}