Enum git_odb::find::Header

source · 
pub enum Header {
    Loose {
        kind: Kind,
        size: u64,
    },
    Packed(Outcome),
}
Expand description

An object header informing about object properties, without it being fully decoded in the process.

Variants§

§

Loose

Fields

§kind: Kind

The kind of the object.

§size: u64

The size of the object’s data in bytes.

The object was not packed, but is currently located in the loose object portion of the database.

As packs are searched first, this means that in this very moment, the object whose header we retrieved is unique in the object database.

§

Packed(Outcome)

The object was present in a pack.

Note that this does not imply it is unique in the database, as it might be present in more than one pack and even as loose object.

Implementations§

Return the object kind of the object we represent.

Examples found in repository?
src/store_impls/dynamic/header.rs (line 141)
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175

    fn try_header_inner<'b>(
        &'b self,
        mut id: &'b git_hash::oid,
        snapshot: &mut load_index::Snapshot,
        recursion: Option<DeltaBaseRecursion<'_>>,
    ) -> Result<Option<Header>, Error> {
        if let Some(r) = recursion {
            if r.depth >= self.max_recursion_depth {
                return Err(Error::DeltaBaseRecursionLimit {
                    max_depth: self.max_recursion_depth,
                    id: r.original_id.to_owned(),
                });
            }
        } else if !self.ignore_replacements {
            if let Ok(pos) = self
                .store
                .replacements
                .binary_search_by(|(map_this, _)| map_this.as_ref().cmp(id))
            {
                id = self.store.replacements[pos].1.as_ref();
            }
        }

        'outer: loop {
            {
                let marker = snapshot.marker;
                for (idx, index) in snapshot.indices.iter_mut().enumerate() {
                    if let Some(handle::index_lookup::Outcome {
                        object_index: handle::IndexForObjectInPack { pack_id, pack_offset },
                        index_file,
                        pack: possibly_pack,
                    }) = index.lookup(id)
                    {
                        let pack = match possibly_pack {
                            Some(pack) => pack,
                            None => match self.store.load_pack(pack_id, marker)? {
                                Some(pack) => {
                                    *possibly_pack = Some(pack);
                                    possibly_pack.as_deref().expect("just put it in")
                                }
                                None => {
                                    // The pack wasn't available anymore so we are supposed to try another round with a fresh index
                                    match self.store.load_one_index(self.refresh, snapshot.marker)? {
                                        Some(new_snapshot) => {
                                            *snapshot = new_snapshot;
                                            self.clear_cache();
                                            continue 'outer;
                                        }
                                        None => {
                                            // nothing new in the index, kind of unexpected to not have a pack but to also
                                            // to have no new index yet. We set the new index before removing any slots, so
                                            // this should be observable.
                                            return Ok(None);
                                        }
                                    }
                                }
                            },
                        };
                        let entry = pack.entry(pack_offset);
                        let res = match pack.decode_header(entry, |id| {
                            index_file.pack_offset_by_id(id).map(|pack_offset| {
                                git_pack::data::decode::header::ResolvedBase::InPack(pack.entry(pack_offset))
                            })
                        }) {
                            Ok(header) => Ok(header.into()),
                            Err(git_pack::data::decode::Error::DeltaBaseUnresolved(base_id)) => {
                                // Only with multi-pack indices it's allowed to jump to refer to other packs within this
                                // multi-pack. Otherwise this would constitute a thin pack which is only allowed in transit.
                                // However, if we somehow end up with that, we will resolve it safely, even though we could
                                // avoid handling this case and error instead.
                                let hdr = self
                                    .try_header_inner(
                                        &base_id,
                                        snapshot,
                                        recursion
                                            .map(|r| r.inc_depth())
                                            .or_else(|| DeltaBaseRecursion::new(id).into()),
                                    )
                                    .map_err(|err| Error::DeltaBaseLookup {
                                        err: Box::new(err),
                                        base_id,
                                        id: id.to_owned(),
                                    })?
                                    .ok_or_else(|| Error::DeltaBaseMissing {
                                        base_id,
                                        id: id.to_owned(),
                                    })?;
                                let handle::index_lookup::Outcome {
                                    object_index:
                                        handle::IndexForObjectInPack {
                                            pack_id: _,
                                            pack_offset,
                                        },
                                    index_file,
                                    pack: possibly_pack,
                                } = match snapshot.indices[idx].lookup(id) {
                                    Some(res) => res,
                                    None => {
                                        let mut out = None;
                                        for index in snapshot.indices.iter_mut() {
                                            out = index.lookup(id);
                                            if out.is_some() {
                                                break;
                                            }
                                        }

                                        out.unwrap_or_else(|| {
                                            panic!("could not find object {} in any index after looking up one of its base objects {}", id, base_id)
                                        })
                                    }
                                };
                                let pack = possibly_pack
                                    .as_ref()
                                    .expect("pack to still be available like just now");
                                let entry = pack.entry(pack_offset);
                                pack.decode_header(entry, |id| {
                                    index_file
                                        .pack_offset_by_id(id)
                                        .map(|pack_offset| {
                                            git_pack::data::decode::header::ResolvedBase::InPack(
                                                pack.entry(pack_offset),
                                            )
                                        })
                                        .or_else(|| {
                                            (id == base_id).then(|| {
                                                git_pack::data::decode::header::ResolvedBase::OutOfPack {
                                                    kind: hdr.kind(),
                                                    num_deltas: hdr.num_deltas(),
                                                }
                                            })
                                        })
                                })
                                .map(Into::into)
                            }
                            Err(err) => Err(err),
                        }?;

                        if idx != 0 {
                            snapshot.indices.swap(0, idx);
                        }
                        return Ok(Some(res));
                    }
                }
            }

            for lodb in snapshot.loose_dbs.iter() {
                // TODO: remove this double-lookup once the borrow checker allows it.
                if lodb.contains(id) {
                    return lodb.try_header(id).map(|opt| opt.map(Into::into)).map_err(Into::into);
                }
            }

            match self.store.load_one_index(self.refresh, snapshot.marker)? {
                Some(new_snapshot) => {
                    *snapshot = new_snapshot;
                    self.clear_cache();
                }
                None => return Ok(None),
            }
        }
    }

Return the size of the object in bytes.

Return the amount of deltas decoded to obtain this header, if the object was packed.

Examples found in repository?
src/store_impls/dynamic/header.rs (line 142)
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175

    fn try_header_inner<'b>(
        &'b self,
        mut id: &'b git_hash::oid,
        snapshot: &mut load_index::Snapshot,
        recursion: Option<DeltaBaseRecursion<'_>>,
    ) -> Result<Option<Header>, Error> {
        if let Some(r) = recursion {
            if r.depth >= self.max_recursion_depth {
                return Err(Error::DeltaBaseRecursionLimit {
                    max_depth: self.max_recursion_depth,
                    id: r.original_id.to_owned(),
                });
            }
        } else if !self.ignore_replacements {
            if let Ok(pos) = self
                .store
                .replacements
                .binary_search_by(|(map_this, _)| map_this.as_ref().cmp(id))
            {
                id = self.store.replacements[pos].1.as_ref();
            }
        }

        'outer: loop {
            {
                let marker = snapshot.marker;
                for (idx, index) in snapshot.indices.iter_mut().enumerate() {
                    if let Some(handle::index_lookup::Outcome {
                        object_index: handle::IndexForObjectInPack { pack_id, pack_offset },
                        index_file,
                        pack: possibly_pack,
                    }) = index.lookup(id)
                    {
                        let pack = match possibly_pack {
                            Some(pack) => pack,
                            None => match self.store.load_pack(pack_id, marker)? {
                                Some(pack) => {
                                    *possibly_pack = Some(pack);
                                    possibly_pack.as_deref().expect("just put it in")
                                }
                                None => {
                                    // The pack wasn't available anymore so we are supposed to try another round with a fresh index
                                    match self.store.load_one_index(self.refresh, snapshot.marker)? {
                                        Some(new_snapshot) => {
                                            *snapshot = new_snapshot;
                                            self.clear_cache();
                                            continue 'outer;
                                        }
                                        None => {
                                            // nothing new in the index, kind of unexpected to not have a pack but to also
                                            // to have no new index yet. We set the new index before removing any slots, so
                                            // this should be observable.
                                            return Ok(None);
                                        }
                                    }
                                }
                            },
                        };
                        let entry = pack.entry(pack_offset);
                        let res = match pack.decode_header(entry, |id| {
                            index_file.pack_offset_by_id(id).map(|pack_offset| {
                                git_pack::data::decode::header::ResolvedBase::InPack(pack.entry(pack_offset))
                            })
                        }) {
                            Ok(header) => Ok(header.into()),
                            Err(git_pack::data::decode::Error::DeltaBaseUnresolved(base_id)) => {
                                // Only with multi-pack indices it's allowed to jump to refer to other packs within this
                                // multi-pack. Otherwise this would constitute a thin pack which is only allowed in transit.
                                // However, if we somehow end up with that, we will resolve it safely, even though we could
                                // avoid handling this case and error instead.
                                let hdr = self
                                    .try_header_inner(
                                        &base_id,
                                        snapshot,
                                        recursion
                                            .map(|r| r.inc_depth())
                                            .or_else(|| DeltaBaseRecursion::new(id).into()),
                                    )
                                    .map_err(|err| Error::DeltaBaseLookup {
                                        err: Box::new(err),
                                        base_id,
                                        id: id.to_owned(),
                                    })?
                                    .ok_or_else(|| Error::DeltaBaseMissing {
                                        base_id,
                                        id: id.to_owned(),
                                    })?;
                                let handle::index_lookup::Outcome {
                                    object_index:
                                        handle::IndexForObjectInPack {
                                            pack_id: _,
                                            pack_offset,
                                        },
                                    index_file,
                                    pack: possibly_pack,
                                } = match snapshot.indices[idx].lookup(id) {
                                    Some(res) => res,
                                    None => {
                                        let mut out = None;
                                        for index in snapshot.indices.iter_mut() {
                                            out = index.lookup(id);
                                            if out.is_some() {
                                                break;
                                            }
                                        }

                                        out.unwrap_or_else(|| {
                                            panic!("could not find object {} in any index after looking up one of its base objects {}", id, base_id)
                                        })
                                    }
                                };
                                let pack = possibly_pack
                                    .as_ref()
                                    .expect("pack to still be available like just now");
                                let entry = pack.entry(pack_offset);
                                pack.decode_header(entry, |id| {
                                    index_file
                                        .pack_offset_by_id(id)
                                        .map(|pack_offset| {
                                            git_pack::data::decode::header::ResolvedBase::InPack(
                                                pack.entry(pack_offset),
                                            )
                                        })
                                        .or_else(|| {
                                            (id == base_id).then(|| {
                                                git_pack::data::decode::header::ResolvedBase::OutOfPack {
                                                    kind: hdr.kind(),
                                                    num_deltas: hdr.num_deltas(),
                                                }
                                            })
                                        })
                                })
                                .map(Into::into)
                            }
                            Err(err) => Err(err),
                        }?;

                        if idx != 0 {
                            snapshot.indices.swap(0, idx);
                        }
                        return Ok(Some(res));
                    }
                }
            }

            for lodb in snapshot.loose_dbs.iter() {
                // TODO: remove this double-lookup once the borrow checker allows it.
                if lodb.contains(id) {
                    return lodb.try_header(id).map(|opt| opt.map(Into::into)).map_err(Into::into);
                }
            }

            match self.store.load_one_index(self.refresh, snapshot.marker)? {
                Some(new_snapshot) => {
                    *snapshot = new_snapshot;
                    self.clear_cache();
                }
                None => return Ok(None),
            }
        }
    }

Trait Implementations§

Returns a copy of the value. Read more
Performs copy-assignment from source. Read more
Formats the value using the given formatter. Read more
Converts to this type from the input type.
Converts to this type from the input type.
Feeds this value into the given Hasher. Read more
Feeds a slice of this type into the given Hasher. Read more
This method returns an Ordering between self and other. Read more
Compares and returns the maximum of two values. Read more
Compares and returns the minimum of two values. Read more
Restrict a value to a certain interval. Read more
This method tests for self and other values to be equal, and is used by ==.
This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.
This method returns an ordering between self and other values if one exists. Read more
This method tests less than (for self and other) and is used by the < operator. Read more
This method tests less than or equal to (for self and other) and is used by the <= operator. Read more
This method tests greater than (for self and other) and is used by the > operator. Read more
This method tests greater than or equal to (for self and other) and is used by the >= operator. Read more

Auto Trait Implementations§

Blanket Implementations§

Gets the TypeId of self. Read more
Immutably borrows from an owned value. Read more
Mutably borrows from an owned value. Read more
Checks if this value is equivalent to the given key. Read more

Returns the argument unchanged.

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

The resulting type after obtaining ownership.
Creates owned data from borrowed data, usually by cloning. Read more
Uses borrowed data to replace owned data, usually by cloning. Read more
The type returned in the event of a conversion error.
Performs the conversion.
The type returned in the event of a conversion error.
Performs the conversion.