holochain_sqlite 0.7.0-dev.15

Abstractions for persistence of Holochain state via SQLite
Documentation 
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use crate::prelude::*;
use holochain_util::timed;
use rusqlite::*;
use std::ops::{Deref, DerefMut};

pub(super) type PConnInner = r2d2::PooledConnection<r2d2_sqlite::SqliteConnectionManager>;

/// Singleton Connection
pub(super) struct PConn {
    inner: PConnInner,
}

impl Deref for PConn {
    type Target = PConnInner;

    fn deref(&self) -> &Self::Target {
        &self.inner
    }
}

impl DerefMut for PConn {
    fn deref_mut(&mut self) -> &mut Self::Target {
        &mut self.inner
    }
}

impl<'e> PConn {
    pub(super) fn new(inner: PConnInner) -> Self {
        Self { inner }
    }

    #[cfg_attr(feature = "instrument", tracing::instrument(skip_all))]
    pub(super) fn execute_in_read_txn<E, R, F>(&'e mut self, f: F) -> Result<R, E>
    where
        E: From<DatabaseError>,
        F: 'e + FnOnce(Transaction) -> Result<R, E>,
    {
        let txn = timed!(
            [1, 100, 1000],
            "acquiring read transaction",
            self.transaction().map_err(DatabaseError::from)?
        );

        // TODO It would be possible to prevent the transaction from calling commit here if we passed a reference instead of a move.
        timed!([10, 20, 50], "running closure", { f(txn) })
    }

    /// Run a closure, passing in a mutable reference to a read-write
    /// transaction, and commit the transaction after the closure has run.
    /// If there is a SQLite error, recover from it and re-run the closure.
    // FIXME: B-01566: implement write failure detection
    #[cfg_attr(feature = "instrument", tracing::instrument(skip_all))]
    pub(super) fn execute_in_exclusive_rw_txn<E, R, F>(&'e mut self, f: F) -> Result<R, E>
    where
        E: From<DatabaseError>,
        F: 'e + FnOnce(&mut Transaction) -> Result<R, E>,
    {
        tracing::trace!("entered execute_in_exclusive_rw_txn");

        let mut txn = timed!([10, 100, 1000], "getting exclusive r/w transaction", {
            self.transaction_with_behavior(TransactionBehavior::Exclusive)
                .map_err(DatabaseError::from)?
        });

        let result = timed!([10, 100, 1000], "running closure", f(&mut txn)?);

        timed!(
            [10, 100, 1000],
            "comitting transaction",
            txn.commit().map_err(DatabaseError::from)?
        );

        Ok(result)
    }
}