test(file_store): last_write_is_short
This test simulates a situation where the last write to the db is short. Aggregating the changeset after reopening the file should return an error (which includes a partially-aggregated changeset) containing an aggregation of changesets that were fully written. At this point, the test re-writes the final changeset (and this time it successfully writes in full). The file should be recoverable with all changesets, including the last one.
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@ -219,6 +219,7 @@ mod test {
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use bincode::DefaultOptions;
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use std::{
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collections::BTreeSet,
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io::{Read, Write},
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vec::Vec,
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};
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@ -228,7 +229,7 @@ mod test {
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const TEST_MAGIC_BYTES: [u8; TEST_MAGIC_BYTES_LEN] =
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[98, 100, 107, 102, 115, 49, 49, 49, 49, 49, 49, 49];
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type TestChangeSet = Vec<String>;
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type TestChangeSet = BTreeSet<String>;
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#[derive(Debug)]
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struct TestTracker;
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@ -253,7 +254,7 @@ mod test {
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fn open_or_create_new() {
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let temp_dir = tempfile::tempdir().unwrap();
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let file_path = temp_dir.path().join("db_file");
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let changeset = vec!["hello".to_string(), "world".to_string()];
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let changeset = BTreeSet::from(["hello".to_string(), "world".to_string()]);
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{
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let mut db = Store::<TestChangeSet>::open_or_create_new(&TEST_MAGIC_BYTES, &file_path)
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@ -304,7 +305,7 @@ mod test {
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let mut data = [255_u8; 2000];
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data[..TEST_MAGIC_BYTES_LEN].copy_from_slice(&TEST_MAGIC_BYTES);
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let changeset = vec!["one".into(), "two".into(), "three!".into()];
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let changeset = TestChangeSet::from(["one".into(), "two".into(), "three!".into()]);
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let mut file = NamedTempFile::new().unwrap();
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file.write_all(&data).expect("should write");
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@ -340,4 +341,73 @@ mod test {
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assert_eq!(got_bytes, expected_bytes);
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}
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#[test]
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fn last_write_is_short() {
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let temp_dir = tempfile::tempdir().unwrap();
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let changesets = [
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TestChangeSet::from(["1".into()]),
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TestChangeSet::from(["2".into(), "3".into()]),
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TestChangeSet::from(["4".into(), "5".into(), "6".into()]),
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];
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let last_changeset = TestChangeSet::from(["7".into(), "8".into(), "9".into()]);
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let last_changeset_bytes = bincode_options().serialize(&last_changeset).unwrap();
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for short_write_len in 1..last_changeset_bytes.len() - 1 {
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let file_path = temp_dir.path().join(format!("{}.dat", short_write_len));
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println!("Test file: {:?}", file_path);
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// simulate creating a file, writing data where the last write is incomplete
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{
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let mut db =
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Store::<TestChangeSet>::create_new(&TEST_MAGIC_BYTES, &file_path).unwrap();
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for changeset in &changesets {
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db.append_changeset(changeset).unwrap();
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}
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// this is the incomplete write
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db.db_file
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.write_all(&last_changeset_bytes[..short_write_len])
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.unwrap();
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}
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// load file again and aggregate changesets
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// write the last changeset again (this time it succeeds)
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{
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let mut db = Store::<TestChangeSet>::open(&TEST_MAGIC_BYTES, &file_path).unwrap();
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let err = db
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.aggregate_changesets()
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.expect_err("should return error as last read is short");
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assert_eq!(
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err.changeset,
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changesets.iter().cloned().reduce(|mut acc, cs| {
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Append::append(&mut acc, cs);
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acc
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}),
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"should recover all changesets that are written in full",
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);
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db.db_file.write_all(&last_changeset_bytes).unwrap();
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}
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// load file again - this time we should successfully aggregate all changesets
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{
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let mut db = Store::<TestChangeSet>::open(&TEST_MAGIC_BYTES, &file_path).unwrap();
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let aggregated_changesets = db
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.aggregate_changesets()
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.expect("aggregating all changesets should succeed");
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assert_eq!(
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aggregated_changesets,
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changesets
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.iter()
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.cloned()
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.chain(core::iter::once(last_changeset.clone()))
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.reduce(|mut acc, cs| {
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Append::append(&mut acc, cs);
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acc
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}),
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"should recover all changesets",
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);
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}
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}
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}
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}
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