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Bug 2019091 - Reset Nimbus databases that are on v1 #7243

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Bug 2019091 - Reset Nimbus databases that are on v1 #7243

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101 changes: 9 additions & 92 deletions components/nimbus/src/stateful/persistence.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -25,7 +25,15 @@ use crate::error::{NimbusError, Result, debug, info, warn};
//
// ⚠️ Warning : Altering the type of `DB_VERSION` would itself require a DB migration. ⚠️
pub(crate) const DB_KEY_DB_VERSION: &str = "db_version";

/// The current database version.
pub(crate) const DB_VERSION: u16 = 3;

/// The minimum database version that will be migrated.
///
/// If the version is below this threshold, the database will be reset.
pub(crate) const DB_MIN_VERSION: u16 = 2;

const RKV_MAX_DBS: u32 = 6;

pub(crate) const DB_KEY_EXPERIMENT_PARTICIPATION: &str = "user-opt-in-experiments";
Expand Down Expand Up @@ -355,7 +363,7 @@ impl Database {
return Ok(());
}

if current_version == 0 || current_version > DB_VERSION {
if current_version == 0 || current_version > DB_VERSION || current_version < DB_MIN_VERSION {
info!(
"maybe_upgrade: current_version: {}, DB_VERSION: {}; wiping most stores",
current_version, DB_VERSION
Expand All @@ -368,18 +376,6 @@ impl Database {
return Ok(());
}

if current_version == 1 {
info!("Migrating database from v1 to v2");
if let Err(e) = self.migrate_v1_to_v2(&mut writer) {
error_support::report_error!(
"nimbus-database-migration",
"Error migrating database v1 to v2: {:?}. Wiping experiments and enrollments",
e
);
self.clear_experiments_and_enrollments(&mut writer)?;
}
}

if current_version == 2 {
info!("Migrating database from v2 to v3");
if let Err(e) = self.migrate_v2_to_v3(&mut writer) {
Expand Down Expand Up @@ -418,85 +414,6 @@ impl Database {
Ok(())
}

/// Migrates a v1 database to v2
///
/// Note that any Err returns from this function (including stuff
/// propagated up via the ? operator) will cause maybe_update (our caller)
/// to assume that this is unrecoverable and wipe the database, removing
/// people from any existing enrollments and blowing away their experiment
/// history, so that they don't get left in an inconsistent state.
fn migrate_v1_to_v2(&self, writer: &mut Writer) -> Result<()> {
info!("Upgrading from version 1 to version 2");

// use try_collect_all to read everything except records that serde
// returns deserialization errors on. Some logging of those errors
// happens, but it's not ideal.
let reader = self.read()?;

// XXX write a test to verify that we don't need to gc any
// enrollments that don't have experiments because the experiments
// were discarded either during try_collect_all (these wouldn't have been
// detected during the filtering phase) or during the filtering phase
// itself. The test needs to run evolve_experiments, as that should
// correctly drop any orphans, even if the migrators aren't perfect.

let enrollments: Vec<ExperimentEnrollment> =
self.enrollment_store.try_collect_all(&reader)?;
let experiments: Vec<Experiment> = self.experiment_store.try_collect_all(&reader)?;

// figure out which experiments have records that need to be dropped
// and log that we're going to drop them and why
let empty_string = "".to_string();
let slugs_with_experiment_issues: HashSet<String> = experiments
.iter()
.filter_map(
|e| {
let branch_with_empty_feature_ids =
e.branches.iter().find(|b| b.feature.is_none() || b.feature.as_ref().unwrap().feature_id.is_empty());
if branch_with_empty_feature_ids.is_some() {
warn!("{:?} experiment has branch missing a feature prop; experiment & enrollment will be discarded", &e.slug);
Some(e.slug.to_owned())
} else if e.feature_ids.is_empty() || e.feature_ids.contains(&empty_string) {
warn!("{:?} experiment has invalid feature_ids array; experiment & enrollment will be discarded", &e.slug);
Some(e.slug.to_owned())
} else {
None
}
})
.collect();
let slugs_to_discard: HashSet<_> = slugs_with_experiment_issues;

// filter out experiments to be dropped
let updated_experiments: Vec<Experiment> = experiments
.into_iter()
.filter(|e| !slugs_to_discard.contains(&e.slug))
.collect();
debug!("updated experiments = {:?}", updated_experiments);

// filter out enrollments to be dropped
let updated_enrollments: Vec<ExperimentEnrollment> = enrollments
.into_iter()
.filter(|e| !slugs_to_discard.contains(&e.slug))
.collect();
debug!("updated enrollments = {:?}", updated_enrollments);

// rewrite both stores
self.experiment_store.clear(writer)?;
for experiment in updated_experiments {
self.experiment_store
.put(writer, &experiment.slug, &experiment)?;
}

self.enrollment_store.clear(writer)?;
for enrollment in updated_enrollments {
self.enrollment_store
.put(writer, &enrollment.slug, &enrollment)?;
}
debug!("exiting migrate_v1_to_v2");

Ok(())
}

/// Migrates a v2 database to v3
///
/// Separates global user participation into experiments and rollouts participation.
Expand Down