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use crate::error::{SRes, StructsyError};
use crate::filter_builder::FilterBuilder;
use crate::id::raw_parse;
use crate::queries::SnapshotQuery;
use crate::record::Record;
use crate::structsy::StructsyImpl;
use crate::{Fetch, Persistent, RawAccess, RawIter, RawRead, Ref, StructsyIter};
use persy::PersyId;
use std::io::Cursor;
use std::marker::PhantomData;
use std::sync::Arc;
/// Read data from a snapshot freezed in a specific moment ignoring all
/// the subsequent committed transactions.
///
#[derive(Clone)]
pub struct Snapshot {
pub(crate) structsy_impl: Arc<StructsyImpl>,
pub(crate) ps: persy::Snapshot,
}
impl Snapshot {
/// Read a persistent instance.
///
/// # Example
/// ```
/// use structsy::{Structsy,StructsyTx};
/// use structsy_derive::Persistent;
/// #[derive(Persistent)]
/// struct Example {
/// value:u8,
/// }
/// # use structsy::SRes;
/// # fn example() -> SRes<()> {
/// # let structsy = Structsy::open("path/to/file.stry")?;
/// //.. open structsy etc.
/// let mut tx = structsy.begin()?;
/// let id = tx.insert(&Example{value:10})?;
/// tx.commit()?;
/// let snapshot = structsy.snapshot()?;
/// let read = snapshot.read(&id)?;
/// assert_eq!(10,read.unwrap().value);
/// # Ok(())
/// # }
/// ```
pub fn read<T: Persistent>(&self, sref: &Ref<T>) -> SRes<Option<T>> {
self.structsy_impl.read_snapshot(self, sref)
}
/// Scan records of a specific struct.
///
///
/// # Example
/// ```
/// use structsy::Structsy;
/// use structsy_derive::Persistent;
/// #[derive(Persistent)]
/// struct Simple {
/// name:String,
/// }
/// # use structsy::SRes;
/// # fn example() -> SRes<()> {
/// let stry = Structsy::open("path/to/file.stry")?;
/// stry.define::<Simple>()?;
/// let snapshot = stry.snapshot()?;
/// for (id, inst) in snapshot.scan::<Simple>()? {
/// // logic here
/// }
/// # Ok(())
/// # }
/// ```
pub fn scan<T: Persistent>(&self) -> SRes<SnapshotRecordIter<T>> {
self.structsy_impl.scan_snapshot::<T>(self)
}
/// Execute a filter query and return an iterator of results for the current snapshot
///
///
/// # Example
/// ```
/// use structsy::{ Structsy, StructsyTx, StructsyError, Filter};
/// use structsy_derive::{queries, embedded_queries, Persistent, PersistentEmbedded};
///
/// #[derive(Persistent)]
/// struct WithEmbedded {
/// embedded: Embedded,
/// }
///
/// #[derive(PersistentEmbedded)]
/// struct Embedded {
/// name: String,
/// }
/// impl WithEmbedded {
/// fn new(name: &str) -> WithEmbedded {
/// WithEmbedded {
/// embedded: Embedded { name: name.to_string() },
/// }
/// }
/// }
///
/// #[queries(WithEmbedded)]
/// trait WithEmbeddedQuery {
/// fn embedded(self, embedded: Filter<Embedded>) -> Self;
/// }
///
/// #[embedded_queries(Embedded)]
/// trait EmbeddedQuery {
/// fn by_name(self, name: String) -> Self;
/// }
///
/// fn embedded_query() -> Result<(), StructsyError> {
/// let structsy = Structsy::open("file.structsy")?;
/// structsy.define::<WithEmbedded>()?;
/// let mut tx = structsy.begin()?;
/// tx.insert(&WithEmbedded::new("aaa"))?;
/// tx.commit()?;
/// let snapshot = structsy.snapshot()?;
/// let embedded_filter = Filter::<Embedded>::new().by_name("aaa".to_string());
/// let filter = Filter::<WithEmbedded>::new().embedded(embedded_filter);
/// let count = snapshot.fetch(filter).count();
/// assert_eq!(count, 1);
/// Ok(())
/// }
/// ```
pub fn fetch<R: Fetch<T>, T>(&self, filter: R) -> StructsyIter<T> {
filter.fetch_snapshot(self)
}
///
/// Query for a persistent struct in the snapshot
///
/// # Example
/// ```
/// use structsy::{ Structsy, StructsyTx, StructsyError};
/// use structsy_derive::{queries, Persistent};
/// #[derive(Persistent)]
/// struct Basic {
/// name: String,
/// }
/// impl Basic {
/// fn new(name: &str) -> Basic {
/// Basic { name: name.to_string() }
/// }
/// }
///
/// #[queries(Basic)]
/// trait BasicQuery {
/// fn by_name(self, name: String) -> Self;
/// }
///
/// fn basic_query() -> Result<(), StructsyError> {
/// let structsy = Structsy::open("file.structsy")?;
/// structsy.define::<Basic>()?;
/// let mut tx = structsy.begin()?;
/// tx.insert(&Basic::new("aaa"))?;
/// tx.commit()?;
/// let snapshot = structsy.snapshot()?;
/// let count = snapshot.query::<Basic>().by_name("aaa".to_string()).fetch().count();
/// assert_eq!(count, 1);
/// Ok(())
/// }
/// ```
pub fn query<T: Persistent + 'static>(&self) -> SnapshotQuery<T> {
SnapshotQuery {
snapshot: self.clone(),
builder: FilterBuilder::new(),
}
}
pub fn list_defined(&self) -> SRes<impl std::iter::Iterator<Item = crate::desc::Description>> {
self.structsy_impl.list_defined()
}
}
impl RawRead for Snapshot {
fn raw_scan(&self, strct_name: &str) -> SRes<RawIter> {
let definition = self.structsy_impl.full_definition_by_name(strct_name)?;
Ok(RawIter::new(
self.structsy_impl.persy.scan(&definition.info().segment_name())?,
definition,
))
}
fn raw_read(&self, id: &str) -> SRes<Option<Record>> {
let (ty, pid) = raw_parse(id)?;
let definition = self.structsy_impl.full_definition_by_name(ty)?;
let rid: PersyId = pid.parse().or(Err(StructsyError::InvalidId))?;
let raw = self.structsy_impl.persy.read(&definition.info().segment_name(), &rid)?;
if let Some(data) = raw {
Ok(Some(Record::read(&mut Cursor::new(data), &definition.desc)?))
} else {
Ok(None)
}
}
}
impl RawAccess for Snapshot {
fn raw_begin(&self) -> SRes<crate::structsy::RawTransaction> {
unimplemented!()
}
fn raw_define(&self, _desc: crate::Description) -> SRes<bool> {
unimplemented!()
}
}
pub trait SnapshotIterator: Iterator {
fn snapshot(&self) -> &Snapshot;
}
/// Iterator for record instances
pub struct SnapshotRecordIter<T> {
iter: persy::SnapshotSegmentIter,
snapshot: Snapshot,
marker: PhantomData<T>,
}
impl<T> SnapshotRecordIter<T> {
pub(crate) fn new(iter: persy::SnapshotSegmentIter, snapshot: Snapshot) -> Self {
SnapshotRecordIter {
iter,
snapshot,
marker: PhantomData,
}
}
}
impl<T: Persistent> Iterator for SnapshotRecordIter<T> {
type Item = (Ref<T>, T);
fn next(&mut self) -> Option<Self::Item> {
if let Some((id, buff)) = self.iter.next() {
if let Ok(x) = T::read(&mut Cursor::new(buff)) {
Some((Ref::new(id), x))
} else {
None
}
} else {
None
}
}
}
impl<T: Persistent> SnapshotIterator for SnapshotRecordIter<T> {
fn snapshot(&self) -> &Snapshot {
&self.snapshot
}
}