hydracache-server 0.70.0

Standalone production server daemon for HydraCache.
Documentation
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#[path = "support/daemon_cluster.rs"]
mod daemon_cluster;

use std::collections::BTreeMap;
use std::time::{Duration, Instant};

use daemon_cluster::{skip_unless_daemon_process_e2e, DaemonCluster, DaemonStatus, TestResult};
use hydracache::{
    ClusterEpoch, ClusterGeneration, ClusterNodeId, ClusterRole, RaftMetadataCommand,
};
use hydracache_cluster_raft::RaftMetadataCommandEnvelope;
use hydracache_cluster_testkit::reference_model::ReferenceMetadataModel;
use serde_json::Value;

const WIDE_SEED: u64 = 0x0660_0008_0001;

#[test]
fn process_committed_metadata_matches_reference_model_wide() -> TestResult {
    if !skip_unless_daemon_process_e2e("process_committed_metadata_matches_reference_model_wide") {
        return Ok(());
    }

    let mut cluster =
        DaemonCluster::start_bootstrap_with_raft_compaction(3, "process-differential-reference")?;
    cluster.wait_for_shape(3, 3)?;
    let initial = external_view(&mut cluster)?;
    let mut model = model_from_initial_view(&initial)?;
    assert_external_matches_model(&initial, &model, "initial bootstrap")?;

    let mut state = WIDE_SEED;
    for step in 0..6 {
        let statuses = cluster.wait_for_shape(3, 3)?;
        let current_leader_index = leader_index(&cluster, &statuses)?;
        let followers = (0..cluster.node_ids().len())
            .filter(|index| *index != current_leader_index)
            .collect::<Vec<_>>();
        state = next_seed(state);
        let restart_index = followers[(state as usize) % followers.len()];
        let restarting_node = ClusterNodeId::from(cluster.node_ids()[restart_index].clone());
        let before_generation = model
            .view()
            .members
            .get(&restarting_node)
            .copied()
            .ok_or_else(|| format!("model lost scheduled node {restarting_node}"))?;

        cluster.kill(restart_index)?;
        cluster.wait_for_responsive_shape(2, 3, 3)?;
        let during_fault = external_view(&mut cluster)?;
        assert_external_matches_model(
            &during_fault,
            &model,
            &format!("step {step} follower stopped"),
        )?;

        if step % 2 == 0 {
            let live_statuses = cluster.wait_for_responsive_shape(2, 3, 3)?;
            let live_leader = leader_index(&cluster, &live_statuses)?;
            let _ = cluster.compact_raft_log(live_leader)?;
            let after_compaction = external_view(&mut cluster)?;
            assert_external_matches_model(
                &after_compaction,
                &model,
                &format!("step {step} compaction"),
            )?;
        }

        cluster.restart(restart_index)?;
        cluster.wait_for_shape(3, 3)?;
        let predicted_epoch = ClusterEpoch::new(model.view().epoch.value().saturating_add(1));
        let predicted_generation =
            ClusterGeneration::new(before_generation.value().saturating_add(1));
        apply_member_upsert(
            &mut model,
            restarting_node,
            predicted_generation,
            predicted_epoch,
        )?;
        let recovered = external_view(&mut cluster)?;
        assert_external_matches_model(
            &recovered,
            &model,
            &format!("step {step} follower restarted"),
        )?;
    }

    let statuses = cluster.wait_for_shape(3, 3)?;
    let current_leader_index = leader_index(&cluster, &statuses)?;
    let drain_index = (0..cluster.node_ids().len())
        .find(|index| *index != current_leader_index)
        .ok_or("wide differential schedule needs a follower to drain")?;
    let drained_node = ClusterNodeId::from(cluster.node_ids()[drain_index].clone());
    let _ = cluster.drain(drain_index)?;
    cluster.wait_for_non_draining_shape("differential drain commits", 2, 2)?;
    let drain_epoch = ClusterEpoch::new(model.view().epoch.value().saturating_add(1));
    apply_node_left(&mut model, drained_node, drain_epoch)?;
    let after_drain = external_view(&mut cluster)?;
    assert_external_matches_model(&after_drain, &model, "committed follower drain")?;

    cluster.kill(drain_index)?;
    cluster.restart(drain_index)?;
    cluster.wait_for_shape(2, 2)?;
    let after_removed_restart = external_view(&mut cluster)?;
    assert_external_matches_model(
        &after_removed_restart,
        &model,
        "removed process restart cannot resurrect membership",
    )?;
    Ok(())
}

#[derive(Debug, Clone, PartialEq, Eq)]
struct ExternalMetadataView {
    epoch: ClusterEpoch,
    members: BTreeMap<ClusterNodeId, ClusterGeneration>,
    leader: ClusterNodeId,
    term: u64,
}

#[derive(Debug, Clone, PartialEq, Eq)]
struct ParsedOverview {
    members: BTreeMap<ClusterNodeId, ClusterGeneration>,
    leader: Option<ParsedLeader>,
}

#[derive(Debug, Clone, PartialEq, Eq)]
struct ParsedLeader {
    node_id: ClusterNodeId,
    term: u64,
    epoch: ClusterEpoch,
}

fn model_from_initial_view(view: &ExternalMetadataView) -> TestResult<ReferenceMetadataModel> {
    let mut model = ReferenceMetadataModel::new();
    for (node_id, generation) in &view.members {
        apply_member_upsert(&mut model, node_id.clone(), *generation, view.epoch)?;
    }
    Ok(model)
}

fn apply_member_upsert(
    model: &mut ReferenceMetadataModel,
    node_id: ClusterNodeId,
    generation: ClusterGeneration,
    epoch: ClusterEpoch,
) -> TestResult {
    let envelope = RaftMetadataCommandEnvelope {
        command_id: format!("member-upsert:{node_id}:{}", generation.value()),
        command: RaftMetadataCommand::MemberUpsert {
            node_id,
            generation,
            epoch,
        },
    };
    model.apply(&envelope).map(|_| ()).map_err(Into::into)
}

fn apply_node_left(
    model: &mut ReferenceMetadataModel,
    node_id: ClusterNodeId,
    epoch: ClusterEpoch,
) -> TestResult {
    let envelope = RaftMetadataCommandEnvelope {
        command_id: format!("node-left:{node_id}:{}", epoch.value()),
        command: RaftMetadataCommand::NodeLeft {
            node_id,
            role: ClusterRole::Member,
            epoch,
        },
    };
    model.apply(&envelope).map(|_| ()).map_err(Into::into)
}

fn assert_external_matches_model(
    external: &ExternalMetadataView,
    model: &ReferenceMetadataModel,
    stage: &str,
) -> TestResult {
    let expected = model.view();
    if external.epoch != expected.epoch || external.members != expected.members {
        return Err(format!(
            "process/reference disagreement at {stage}: external={external:?} model={expected:?}"
        )
        .into());
    }
    if !expected.clients.is_empty() {
        return Err(
            format!("process member schedule unexpectedly modeled clients at {stage}").into(),
        );
    }
    Ok(())
}

fn external_view(cluster: &mut DaemonCluster) -> TestResult<ExternalMetadataView> {
    let deadline = Instant::now() + Duration::from_secs(10);
    let mut latest_error = None;
    while Instant::now() < deadline {
        match try_external_view(cluster) {
            Ok(view) => return Ok(view),
            Err(error) => latest_error = Some(error.to_string()),
        }
        std::thread::sleep(Duration::from_millis(50));
    }
    Err(format!(
        "all responsive daemon views did not converge before {deadline:?}; latest_error={latest_error:?}"
    )
    .into())
}

fn try_external_view(cluster: &mut DaemonCluster) -> TestResult<ExternalMetadataView> {
    let running = cluster.running_indices();
    if running.is_empty() {
        return Err("no running daemon exposed committed metadata".into());
    }

    let mut authoritative = Vec::with_capacity(running.len());
    let mut all_memberships = Vec::with_capacity(running.len());
    for index in running {
        let status = cluster
            .admin_status(index)
            .map_err(|error| format!("daemon {index} admin status failed: {error}"))?;
        let overview = cluster
            .cluster_overview(index)
            .map_err(|error| format!("daemon {index} cluster overview failed: {error}"))?;
        let parsed = parse_external_overview(&overview).map_err(|error| {
            format!(
                "daemon {index} cluster overview is invalid: {error}; status={status:?}; overview={overview}"
            )
        })?;
        if status.members as usize != parsed.members.len() || status.voters != status.members {
            return Err(format!(
                "daemon {index} exposes inconsistent committed shape: status members={} voters={}, overview members={}",
                status.members,
                status.voters,
                parsed.members.len()
            )
            .into());
        }
        all_memberships.push(parsed.members.clone());

        if status.draining {
            if status.quorum_ok || status.leader.is_some() || parsed.leader.is_some() {
                return Err(format!(
                    "draining daemon {index} exposed an authoritative leader: status={status:?}, overview={overview}"
                )
                .into());
            }
            continue;
        }
        if !status.quorum_ok {
            return Err(format!(
                "non-draining daemon {index} reported a non-authoritative view despite being responsive"
            )
            .into());
        }
        let leader = parsed
            .leader
            .ok_or_else(|| format!("authoritative daemon {index} overview has no leader"))?;
        if status.leader.as_deref() != Some(leader.node_id.as_str()) {
            return Err(format!(
                "daemon {index} disagrees across public surfaces: status leader={:?}, overview leader={}",
                status.leader, leader.node_id
            )
            .into());
        }
        if status.term != leader.term {
            return Err(format!(
                "daemon {index} disagrees across public surfaces: status term={}, overview term={}",
                status.term, leader.term
            )
            .into());
        }
        authoritative.push(ExternalMetadataView {
            epoch: leader.epoch,
            members: parsed.members,
            leader: leader.node_id,
            term: leader.term,
        });
    }

    let expected = authoritative
        .first()
        .cloned()
        .ok_or("no responsive daemon exposed an authoritative committed view")?;
    if let Some((index, divergent)) = authoritative
        .iter()
        .enumerate()
        .find(|(_, view)| **view != expected)
    {
        return Err(format!(
            "responsive daemons disagree on committed metadata: first={expected:?}, observation[{index}]={divergent:?}"
        )
        .into());
    }
    if let Some((index, divergent)) = all_memberships
        .iter()
        .enumerate()
        .find(|(_, members)| **members != expected.members)
    {
        return Err(format!(
            "responsive daemon membership disagrees with the authoritative view: authoritative={:?}, membership[{index}]={divergent:?}",
            expected.members
        )
        .into());
    }
    Ok(expected)
}

fn parse_external_overview(overview: &Value) -> TestResult<ParsedOverview> {
    if overview.get("source").and_then(Value::as_str) != Some("live") {
        return Err("cluster overview is not live".into());
    }
    let raw_members = overview
        .get("members")
        .and_then(Value::as_array)
        .ok_or("cluster overview has no members")?;
    let mut members = BTreeMap::new();
    for member in raw_members {
        let node_id = member
            .get("node_id")
            .and_then(Value::as_str)
            .ok_or("cluster overview member has no node_id")?;
        let generation = member
            .get("generation")
            .and_then(Value::as_u64)
            .ok_or("cluster overview member has no generation")?;
        let node_id = ClusterNodeId::from(node_id);
        if members
            .insert(node_id.clone(), ClusterGeneration::new(generation))
            .is_some()
        {
            return Err(format!("cluster overview contains duplicate member {node_id}").into());
        }
    }
    let leader = overview
        .get("leader")
        .filter(|leader| !leader.is_null())
        .map(|leader| -> TestResult<ParsedLeader> {
            let node_id = leader
                .get("node_id")
                .and_then(Value::as_str)
                .ok_or("cluster overview leader has no node_id")?;
            let term = leader
                .get("term")
                .and_then(Value::as_u64)
                .ok_or("cluster overview leader has no term")?;
            let epoch = leader
                .get("epoch")
                .and_then(Value::as_u64)
                .ok_or("cluster overview leader has no epoch")?;
            let node_id = ClusterNodeId::from(node_id);
            if !members.contains_key(&node_id) {
                return Err(
                    format!("cluster overview leader {node_id} is absent from membership").into(),
                );
            }
            Ok(ParsedLeader {
                node_id,
                term,
                epoch: ClusterEpoch::new(epoch),
            })
        })
        .transpose()?;
    Ok(ParsedOverview { members, leader })
}

#[test]
fn process_oracle_rejects_duplicate_or_non_member_leaders() {
    let base = serde_json::json!({
        "source": "live",
        "leader": {"node_id": "member-a", "term": 7, "epoch": 3},
        "members": [
            {"node_id": "member-a", "generation": 1},
            {"node_id": "member-b", "generation": 1}
        ]
    });
    let parsed = parse_external_overview(&base).expect("valid public view");
    let leader = parsed.leader.expect("valid leader");
    assert_eq!(leader.node_id, ClusterNodeId::from("member-a"));
    assert_eq!(leader.term, 7);

    let mut duplicate = base.clone();
    duplicate["members"] = serde_json::json!([
        {"node_id": "member-a", "generation": 1},
        {"node_id": "member-a", "generation": 2}
    ]);
    assert!(parse_external_overview(&duplicate)
        .unwrap_err()
        .to_string()
        .contains("duplicate member"));

    let mut ghost_leader = base;
    ghost_leader["leader"]["node_id"] = Value::String("ghost".to_owned());
    assert!(parse_external_overview(&ghost_leader)
        .unwrap_err()
        .to_string()
        .contains("absent from membership"));
}

fn leader_index(cluster: &DaemonCluster, statuses: &[DaemonStatus]) -> TestResult<usize> {
    let leader = statuses
        .iter()
        .find_map(|status| status.leader.as_deref())
        .ok_or("cluster status did not expose a leader")?;
    cluster
        .node_ids()
        .iter()
        .position(|node_id| node_id == leader)
        .ok_or_else(|| format!("leader {leader} is not a spawned daemon").into())
}

fn next_seed(state: u64) -> u64 {
    state
        .wrapping_mul(6_364_136_223_846_793_005)
        .wrapping_add(1_442_695_040_888_963_407)
}