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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
use crate::RemoteSettingsResponse;
use std::collections::HashSet;
/// Merge a cached RemoteSettingsResponse and a newly downloaded one to get a merged response
///
/// cached is a previously downloaded remote settings response (possibly run through merge_cache_and_response).
/// new is a newly downloaded remote settings response (with `_expected` set to the last_modified
/// time of the cached response).
///
/// This will merge the records from both responses, handle deletions/tombstones, and return a
/// response that has:
/// - The newest `last_modified_date`
/// - A record list containing the newest version of all live records. Deleted records will not
/// be present in this list.
///
/// If everything is working properly, the returned value will exactly match what the server would
/// have returned if there was no `_expected` param.
pub fn merge_cache_and_response(
cached: RemoteSettingsResponse,
new: RemoteSettingsResponse,
) -> RemoteSettingsResponse {
let new_record_ids = new
.records
.iter()
.map(|r| r.id.as_str())
.collect::<HashSet<&str>>();
// Start with any cached records that don't appear in new.
let mut records = cached
.records
.into_iter()
.filter(|r| !new_record_ids.contains(r.id.as_str()))
// deleted should always be false, check it just in case
.filter(|r| !r.deleted)
.collect::<Vec<_>>();
// Add all (non-deleted) records from new
records.extend(new.records.into_iter().filter(|r| !r.deleted));
RemoteSettingsResponse {
last_modified: new.last_modified,
records,
}
}
#[cfg(test)]
mod test {
use super::*;
use crate::{RemoteSettingsRecord, RsJsonObject};
// Quick way to generate the fields data for our mock records
fn fields(data: &str) -> RsJsonObject {
let mut map = serde_json::Map::new();
map.insert("data".into(), data.into());
map
}
#[test]
fn test_combine_cache_and_response() {
let cached_response = RemoteSettingsResponse {
last_modified: 1000,
records: vec![
RemoteSettingsRecord {
id: "a".into(),
last_modified: 100,
deleted: false,
attachment: None,
fields: fields("a"),
},
RemoteSettingsRecord {
id: "b".into(),
last_modified: 200,
deleted: false,
attachment: None,
fields: fields("b"),
},
RemoteSettingsRecord {
id: "c".into(),
last_modified: 300,
deleted: false,
attachment: None,
fields: fields("c"),
},
],
};
let new_response = RemoteSettingsResponse {
last_modified: 2000,
records: vec![
// d is new
RemoteSettingsRecord {
id: "d".into(),
last_modified: 1300,
deleted: false,
attachment: None,
fields: fields("d"),
},
// b was deleted
RemoteSettingsRecord {
id: "b".into(),
last_modified: 1200,
deleted: true,
attachment: None,
fields: RsJsonObject::new(),
},
// a was updated
RemoteSettingsRecord {
id: "a".into(),
last_modified: 1100,
deleted: false,
attachment: None,
fields: fields("a-with-new-data"),
},
// c was not modified, so it's not present in the new response
],
};
let mut merged = merge_cache_and_response(cached_response, new_response);
// Sort the records to make the assertion easier
merged.records.sort_by_key(|r| r.id.clone());
assert_eq!(
merged,
RemoteSettingsResponse {
last_modified: 2000,
records: vec![
// a was updated
RemoteSettingsRecord {
id: "a".into(),
last_modified: 1100,
deleted: false,
attachment: None,
fields: fields("a-with-new-data"),
},
RemoteSettingsRecord {
id: "c".into(),
last_modified: 300,
deleted: false,
attachment: None,
fields: fields("c"),
},
RemoteSettingsRecord {
id: "d".into(),
last_modified: 1300,
deleted: false,
attachment: None,
fields: fields("d"),
},
],
}
);
}
}