postmodern 0.5.0

Postgres-backed job queue with transaction-based locking.
Documentation 
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//! Error types for queue operations.

/// Queue connection errors.
#[derive(Debug, thiserror::Error)]
pub enum ConnectError {
    /// Database connection failed.
    #[error("database connection failed")]
    Database(#[source] sqlx::Error),
    /// Migration failed.
    #[error("migration failed")]
    Migration(#[source] sqlx::migrate::MigrateError),
}

/// Enqueue operation errors.
#[derive(Debug, thiserror::Error)]
pub enum EnqueueError {
    /// Payload serialization failed.
    #[error("failed to serialize payload")]
    Serialize(#[source] rmp_serde::encode::Error),
    /// Database operation failed.
    #[error("database error")]
    Database(#[source] sqlx::Error),
    /// Queue does not exist.
    #[error("queue not found")]
    QueueNotFound,
}

/// Job fetch errors.
#[derive(Debug, thiserror::Error)]
pub enum FetchError {
    /// Query execution failed.
    #[error("query failed")]
    Query(#[source] sqlx::Error),
    /// Payload deserialization failed.
    #[error("failed to deserialize payload for job {0}")]
    Deserialize(uuid::Uuid, #[source] rmp_serde::decode::Error),
}

/// Job listing errors.
#[derive(Debug, thiserror::Error)]
pub enum ListError {
    /// Query execution failed.
    #[error("query failed")]
    Query(#[source] sqlx::Error),
}

/// Job modification errors.
#[derive(Debug, thiserror::Error)]
pub enum ModifyError {
    /// Database operation failed.
    #[error("database error")]
    Database(#[source] sqlx::Error),
    /// Queue does not exist.
    #[error("queue not found")]
    QueueNotFound,
    /// Queue already exists.
    #[error("queue already exists")]
    QueueAlreadyExists,
    /// Transform function failed.
    #[error("transform failed")]
    Transform(#[source] anyhow::Error),
}

/// Job acknowledgment errors.
#[derive(Debug, thiserror::Error)]
pub enum AckError {
    /// Database operation failed.
    #[error("failed to update job")]
    Database(#[source] sqlx::Error),
    /// Lock was lost, likely due to timeout and reaping.
    #[error("lock lost")]
    LockLost,
}

/// Reaper errors.
#[derive(Debug, thiserror::Error)]
pub enum ReapError {
    /// Database operation failed.
    #[error("database error")]
    Database(#[source] sqlx::Error),
}

/// Job ID resolution errors.
#[derive(Debug, thiserror::Error)]
pub enum ResolveIdError {
    /// Query execution failed.
    #[error("query failed")]
    Query(#[source] sqlx::Error),
    /// No job matched the suffix.
    #[error("no job matched '{0}'")]
    NotFound(String),
    /// Multiple jobs matched the suffix.
    #[error("'{suffix}' is ambiguous, matches: {matches}")]
    Ambiguous {
        /// The ambiguous suffix.
        suffix: String,
        /// Comma-separated list of matching short IDs.
        matches: String,
    },
}

/// Errors from advancing to the next pipeline stage.
#[derive(Debug, thiserror::Error)]
pub enum AdvanceError {
    /// Database operation failed.
    #[error("database error")]
    Database(#[source] sqlx::Error),
    /// Advance failed because lock was lost or target queue not found.
    #[error("advance failed (lock lost or queue not found)")]
    Failed,
}

/// Checkpoint operation errors.
#[derive(Debug, thiserror::Error)]
pub enum CheckpointError<E> {
    /// Checkpoint name used more than once in single execution.
    #[error("duplicate checkpoint '{0}' in single execution")]
    DuplicateCheckpoint(String),

    /// Failed to serialize checkpoint value.
    #[error("failed to serialize checkpoint value")]
    Serialize(#[source] rmp_serde::encode::Error),

    /// Failed to deserialize stored checkpoint value.
    #[error("failed to deserialize stored checkpoint value")]
    Deserialize(#[source] rmp_serde::decode::Error),

    /// Database operation failed.
    #[error("database error")]
    Database(#[source] sqlx::Error),

    /// Lock was lost before checkpoint could be written.
    #[error("lock lost")]
    LockLost,

    /// Checkpoint closure returned an error.
    #[error("checkpoint closure failed")]
    Closure(E),
}