use std::path::PathBuf; use crate::store_impl::{file, packed}; impl file::Store {    /// Return a packed transaction ready to receive updates. Use this to create or update `packed-refs`.    /// Note that if you already have a [`packed::Buffer`] then use its [`packed::Buffer::into_transaction()`] method instead.    pub(crate) fn packed_transaction(        &self,        lock_mode: git_lock::acquire::Fail,    ) -> Result<packed::Transaction, transaction::Error> {        let lock = git_lock::File::acquire_to_update_resource(self.packed_refs_path(), lock_mode, None)?;        // We 'steal' the possibly existing packed buffer which may safe time if it's already there and fresh.        // If nothing else is happening, nobody will get to see the soon stale buffer either, but if so, they will pay        // for reloading it. That seems preferred over always loading up a new one.        Ok(packed::Transaction::new_from_pack_and_lock(            self.assure_packed_refs_uptodate()?,            lock,        ))    }     /// Try to open a new packed buffer. It's not an error if it doesn't exist, but yields `Ok(None)`.    pub fn open_packed_buffer(&self) -> Result<Option<packed::Buffer>, packed::buffer::open::Error> {        let need_more_than_this_many_bytes_to_use_mmap = 32 * 1024;        match packed::Buffer::open(self.packed_refs_path(), need_more_than_this_many_bytes_to_use_mmap) {            Ok(buf) => Ok(Some(buf)),            Err(packed::buffer::open::Error::Io(err)) if err.kind() == std::io::ErrorKind::NotFound => Ok(None),            Err(err) => Err(err),        }    }     /// Return a possibly cached packed buffer with shared ownership. At retrieval it will assure it's up to date, but    /// after that it can be considered a snapshot as it cannot change anymore.    ///    /// Use this to make successive calls to [`file::Store::try_find_packed()`]    /// or obtain iterators using [`file::Store::iter_packed()`] in a way that assures the packed-refs content won't change.    pub fn cached_packed_buffer(        &self,    ) -> Result<Option<file::packed::SharedBufferSnapshot>, packed::buffer::open::Error> {        self.assure_packed_refs_uptodate()    }     /// Return the path at which packed-refs would usually be stored    pub fn packed_refs_path(&self) -> PathBuf {        self.common_dir_resolved().join("packed-refs")    }} ///pub mod transaction {    use quick_error::quick_error;     use crate::store_impl::packed;     quick_error! {        /// The error returned by [`file::Store::packed_transaction`][crate::file::Store::packed_transaction()].        #[derive(Debug)]        #[allow(missing_docs)]        pub enum Error {            BufferOpen(err: packed::buffer::open::Error) {                display("An existing pack couldn't be opened or read when preparing a transaction")                source(err)                from()            }            TransactionLock(err: git_lock::acquire::Error) {                display("The lock for a packed transaction could not be obtained")                source(err)                from()            }        }    }} /// An up-to-date snapshot of the packed refs buffer.pub type SharedBufferSnapshot = git_features::fs::SharedSnapshot<packed::Buffer>; pub(crate) mod modifiable {    use git_features::threading::OwnShared;     use crate::{file, packed};     pub(crate) type MutableSharedBuffer = OwnShared<git_features::fs::MutableSnapshot<packed::Buffer>>;     impl file::Store {        pub(crate) fn force_refresh_packed_buffer(&self) -> Result<(), packed::buffer::open::Error> {            self.packed.force_refresh(|| {                let modified = self.packed_refs_path().metadata()?.modified()?;                self.open_packed_buffer().map(|packed| Some(modified).zip(packed))            })        }        pub(crate) fn assure_packed_refs_uptodate(            &self,        ) -> Result<Option<super::SharedBufferSnapshot>, packed::buffer::open::Error> {            self.packed.recent_snapshot(                || self.packed_refs_path().metadata().and_then(|m| m.modified()).ok(),                || self.open_packed_buffer(),            )        }    }}