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|
//! Database schema versions.
use serde::Serialize;
/// The type of schema version components.
pub type VersionComponent = u32;
/// Schema version of the database storing the generation.
///
/// An Obnam client can restore a generation using schema version
/// (x,y), if the client supports a schema version (x,z). If z < y,
/// the client knows it may not be able to the generation faithfully,
/// and should warn the user about this. If z >= y, the client knows
/// it can restore the generation faithfully. If the client does not
/// support any schema version x, it knows it can't restore the backup
/// at all.
#[derive(Debug, Clone, Copy, Serialize)]
pub struct SchemaVersion {
/// Major version.
pub major: VersionComponent,
/// Minor version.
pub minor: VersionComponent,
}
impl SchemaVersion {
/// Create a new schema version object.
pub fn new(major: VersionComponent, minor: VersionComponent) -> Self {
Self { major, minor }
}
/// Return the major and minor version number component of a schema version.
pub fn version(&self) -> (VersionComponent, VersionComponent) {
(self.major, self.minor)
}
/// Is this schema version compatible with another schema version?
pub fn is_compatible_with(&self, other: &Self) -> bool {
self.major == other.major && self.minor >= other.minor
}
}
impl std::fmt::Display for SchemaVersion {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
write!(f, "{}.{}", self.major, self.minor)
}
}
impl std::str::FromStr for SchemaVersion {
type Err = SchemaVersionError;
fn from_str(s: &str) -> Result<Self, Self::Err> {
if let Some(pos) = s.find('.') {
let major = parse_int(&s[..pos])?;
let minor = parse_int(&s[pos + 1..])?;
Ok(SchemaVersion::new(major, minor))
} else {
Err(SchemaVersionError::Invalid(s.to_string()))
}
}
}
fn parse_int(s: &str) -> Result<VersionComponent, SchemaVersionError> {
if let Ok(i) = s.parse() {
Ok(i)
} else {
Err(SchemaVersionError::InvalidComponent(s.to_string()))
}
}
/// Possible errors from parsing schema versions.
#[derive(Debug, thiserror::Error, PartialEq, Eq)]
pub enum SchemaVersionError {
/// Failed to parse a string as a schema version.
#[error("Invalid schema version {0:?}")]
Invalid(String),
/// Failed to parse a string as a schema version component.
#[error("Invalid schema version component {0:?}")]
InvalidComponent(String),
}
#[cfg(test)]
mod test {
use super::*;
use std::str::FromStr;
#[test]
fn from_string() {
let v = SchemaVersion::from_str("1.2").unwrap();
assert_eq!(v.version(), (1, 2));
}
#[test]
fn from_string_fails_if_empty() {
match SchemaVersion::from_str("") {
Err(SchemaVersionError::Invalid(s)) => assert_eq!(s, ""),
_ => unreachable!(),
}
}
#[test]
fn from_string_fails_if_empty_major() {
match SchemaVersion::from_str(".2") {
Err(SchemaVersionError::InvalidComponent(s)) => assert_eq!(s, ""),
_ => unreachable!(),
}
}
#[test]
fn from_string_fails_if_empty_minor() {
match SchemaVersion::from_str("1.") {
Err(SchemaVersionError::InvalidComponent(s)) => assert_eq!(s, ""),
_ => unreachable!(),
}
}
#[test]
fn from_string_fails_if_just_major() {
match SchemaVersion::from_str("1") {
Err(SchemaVersionError::Invalid(s)) => assert_eq!(s, "1"),
_ => unreachable!(),
}
}
#[test]
fn from_string_fails_if_nonnumeric_major() {
match SchemaVersion::from_str("a.2") {
Err(SchemaVersionError::InvalidComponent(s)) => assert_eq!(s, "a"),
_ => unreachable!(),
}
}
#[test]
fn from_string_fails_if_nonnumeric_minor() {
match SchemaVersion::from_str("1.a") {
Err(SchemaVersionError::InvalidComponent(s)) => assert_eq!(s, "a"),
_ => unreachable!(),
}
}
#[test]
fn compatible_with_self() {
let v = SchemaVersion::new(1, 2);
assert!(v.is_compatible_with(&v));
}
#[test]
fn compatible_with_older_minor_version() {
let old = SchemaVersion::new(1, 2);
let new = SchemaVersion::new(1, 3);
assert!(new.is_compatible_with(&old));
}
#[test]
fn not_compatible_with_newer_minor_version() {
let old = SchemaVersion::new(1, 2);
let new = SchemaVersion::new(1, 3);
assert!(!old.is_compatible_with(&new));
}
#[test]
fn not_compatible_with_older_major_version() {
let old = SchemaVersion::new(1, 2);
let new = SchemaVersion::new(2, 0);
assert!(!new.is_compatible_with(&old));
}
#[test]
fn not_compatible_with_newer_major_version() {
let old = SchemaVersion::new(1, 2);
let new = SchemaVersion::new(2, 0);
assert!(!old.is_compatible_with(&new));
}
}
|
