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Implement create_snapshot interface for ImageFile #392

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Merged
BigVan merged 1 commit into from
Feb 2, 2026
Merged

Implement create_snapshot interface for ImageFile #392

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54 changes: 51 additions & 3 deletions src/image_file.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -334,12 +334,12 @@ LSMT::IFileRO *ImageFile::open_lowers(std::vector<ImageConfigNS::LayerConfig> &l
return NULL;

photon::join_handle *ths[PARALLEL_LOAD_INDEX];
std::vector<IFile *> files;
std::vector<IFile *> files; // layer0 ... layerN-1
files.resize(lowers.size(), nullptr);
auto n = std::min(PARALLEL_LOAD_INDEX, (int)lowers.size());
LOG_DEBUG("create ` photon threads to open lowers", n);

ParallelOpenTask tm(files, lowers.size(), lowers);
ParallelOpenTask tm(files, lowers.size(), lowers); // layer0 ... layerN-1
for (auto i = 0; i < n; ++i) {
ths[i] =
photon::thread_enable_join(photon::thread_create11(&do_parallel_open_files, this, tm));
Expand Down Expand Up @@ -443,7 +443,7 @@ int ImageFile::init_image_file() {
ImageConfigNS::UpperConfig upper;
bool record_no_download = false;
bool has_error = false;
auto lowers = conf.lowers();
auto lowers = conf.lowers(); // layer0 ... layerN-1
auto concurrency = image_service.global_conf.prefetchConfig().concurrency();

if (conf.accelerationLayer() && !conf.recordTracePath().empty()) {
Expand Down Expand Up @@ -554,3 +554,51 @@ void ImageFile::set_failed(const Ts &...xs) {
m_exception = estring().appends(xs...);
}
}

int ImageFile::create_snapshot(const char *config_path) {
// load new config file to get the snapshot layer path
// open new upper layer
// restack() current RW layer as snapshot layer
if(!m_lower_file || !m_upper_file)
LOG_ERROR_RETURN(0, -1, "Lower or upper layer is NULL.");

ImageConfigNS::ImageConfig new_cfg;
LSMT::IFileRW *upper_file = nullptr;

LOG_INFO("Load new config `.", config_path);
if (!new_cfg.ParseJSON(config_path)) {
LOG_ERROR_RETURN(0, -1, "Error parse new config json: `.", config_path);
}

auto upper = new_cfg.upper();
auto lowers = new_cfg.lowers();
// if(lowers[lowers.size()-1].file() != conf.upper().data())
// LOG_ERROR_RETURN(0, -1, "The last lower layer(`) should be the same as old upper layer(`) after restack.", lowers[lowers.size()-1].file(), conf.upper().data());
if(upper.index() == conf.upper().index() || upper.data() == conf.upper().data())
LOG_ERROR_RETURN(0, -1, "The new upper layer(`, `) should be different from the old upper layer(`, `).", upper.data(), upper.index(), conf.upper().data(), conf.upper().index());

upper_file = open_upper(upper);
if (!upper_file)
LOG_ERROR_RETURN(0, -1, "Open upper layer failed.");

if(((LSMT::IFileRW *)m_file)->restack(upper_file) != 0)
LOG_ERRNO_RETURN(0, -1, "Restack new rwlayer failed.");

if(m_upper_file) {
// transfer the sealed layer from m_upper_file to m_lower_file before m_upper_file is destructed
auto sealed = ((LSMT::IFileRW *)m_upper_file)->get_file(0);
((LSMT::IFileRO *)m_lower_file)->insert_file(sealed);
((LSMT::IFileRW *)m_upper_file)->clear_files();
delete m_upper_file;
}
// set m_lower_file->m_index = m_file->m_index->m_backing_index because m_file is not responsible for the destruction of m_backing_index
auto combo_index = (LSMT::IComboIndex *)((LSMT::IFileRW *)m_file)->index(); // m_file->m_index
((LSMT::IFileRO *)m_lower_file)->index(combo_index->backing_index());
// set m_file->m_index->m_index0 = upper_file->m_index
auto upper_file_index = (LSMT::IMemoryIndex0 *)((LSMT::IFileRW *)upper_file)->index(); // upper_file->m_index
combo_index->front_index(upper_file_index);

m_upper_file = upper_file;

return 0;
}
8 changes: 1 addition & 7 deletions src/image_file.h
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Original file line number Diff line number Diff line change
Expand Up @@ -119,13 +119,7 @@ class ImageFile : public photon::fs::ForwardFile {

int compact(IFile *as);

int create_snapshot(const char *config_path) {
// load new config file to get the snapshot layer path
// open new upper layer
// restack() current RW layer as snapshot layer
LOG_INFO("call create_snapshot, dev_id: `", m_dev_id);
return 0;
}
int create_snapshot(const char *config_path);

private:
Prefetcher *m_prefetcher = nullptr;
Expand Down
38 changes: 36 additions & 2 deletions src/overlaybd/lsmt/file.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -500,6 +500,20 @@ class LSMTReadOnlyFile : public IFileRW {
return (IMemoryIndex0 *)m_index;
}

virtual int index(const IMemoryIndex *index) override {
if(!index || !index->buffer()) {
errno = EINVAL;
LOG_ERROR("Invalid index!");
return -1;
}
if (m_index != nullptr) {
delete m_index;
m_index = nullptr;
}
m_index = (IMemoryIndex *)index;
return 0;
}

virtual int close() override {
safe_delete(m_index);
if (m_file_ownership) {
Expand All @@ -523,6 +537,23 @@ class LSMTReadOnlyFile : public IFileRW {
return m_files;
}

virtual IFile *get_file(size_t file_idx) const override {
if (file_idx >= m_files.size()) {
LOG_ERROR_RETURN(0, nullptr, "file_idx out of range.");
}
return m_files[file_idx];
}

virtual int insert_file(IFile * file) override {
m_files.insert(m_files.begin(), file);
return 0;
}

virtual int clear_files() override {
m_files.clear();
return 0;
}

template <typename T1, typename T2, typename T3>
inline void forward(void *&buffer, T1 &offset, T2 &count, T3 step) {
(char *&)buffer += step * ALIGNMENT;
Expand Down Expand Up @@ -1038,6 +1069,9 @@ class LSMTFile : public LSMTReadOnlyFile {
m_findex = u->m_findex;
m_vsize = u->m_vsize;
((IComboIndex *)m_index)->commit_index0();

delete fseal;
delete gc_layer;
return 0;
}

Expand Down Expand Up @@ -1333,7 +1367,7 @@ static SegmentMapping *do_load_index(IFile *file, HeaderTrailer *pheader_trailer
auto ret = file->fstat(&stat);
if (ret < 0)
LOG_ERRNO_RETURN(0, nullptr, "failed to stat file.");
assert(pht->is_sparse_rw() == false);
assert(trailer || pht->is_sparse_rw() == false);
uint64_t index_bytes;
if (trailer) {
if (!pht->is_data_file())
Expand Down Expand Up @@ -1738,7 +1772,7 @@ static IMemoryIndex *load_merge_index(vector<IFile *> &files, vector<UUID> &uuid
}
}

std::reverse(files.begin(), files.end());
std::reverse(files.begin(), files.end()); // reverse files: layerN-1 ... layer0
std::reverse(tm.indexes.begin(), tm.indexes.end());
std::reverse(uuid.begin(), uuid.end());
auto pmi = merge_memory_indexes((const IMemoryIndex **)&tm.indexes[0], tm.indexes.size());
Expand Down
8 changes: 8 additions & 0 deletions src/overlaybd/lsmt/file.h
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Original file line number Diff line number Diff line change
Expand Up @@ -46,11 +46,19 @@ class IFileRO : public photon::fs::VirtualReadOnlyFile {

virtual IMemoryIndex *index() const = 0;

virtual int index(const IMemoryIndex *index) = 0;

// return uuid of m_files[layer_idx];
virtual int get_uuid(UUID &out, size_t layer_idx = 0) const = 0;

virtual std::vector<IFile *> get_lower_files() const = 0;

virtual IFile *get_file(size_t file_idx) const = 0;

virtual int insert_file(IFile * file) = 0;

virtual int clear_files() = 0;

virtual ssize_t seek_data(off_t begin, off_t end, std::vector<Segment> &segs) = 0;

virtual int flatten(IFile *as) = 0;
Expand Down
18 changes: 17 additions & 1 deletion src/overlaybd/lsmt/index.cpp
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Expand Up @@ -617,6 +617,7 @@ class Index0 : public IComboIndex {
virtual const IMemoryIndex0 *front_index() const override {
return this;
}
UNIMPLEMENTED(int front_index(const IMemoryIndex0 *fi) override);
UNIMPLEMENTED(size_t vsize() const override);
UNIMPLEMENTED(int commit_index0() override);
};
Expand Down Expand Up @@ -649,6 +650,19 @@ class ComboIndex : public Index0 {
}
}

virtual int front_index(const IMemoryIndex0 *fi) override {
if (!fi) {
errno = EINVAL;
LOG_ERROR("Invalid index!");
return -1;
}
if (m_ownership && m_index0 != nullptr) { // !!!
delete m_index0;
m_index0 = nullptr;
}
m_index0 = (Index0 *)fi;
return 0;
}
virtual const IMemoryIndex0 *front_index() const override {
return this->m_index0;
}
Expand Down Expand Up @@ -759,7 +773,9 @@ class ComboIndex : public Index0 {
p.tag = 0;
merged_index->insert(p);
}
delete m_backing_index;
if(m_ownership) { // !!!
delete m_backing_index;
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@BigVan BigVan Jan 28, 2026

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need { }

}
m_backing_index = (Index*)(merged_index->make_read_only_index()); // set ownership=false
delete merged_index;
LOG_INFO("rebuild backing index done. {count: `}", m_backing_index->size());
Expand Down
1 change: 1 addition & 0 deletions src/overlaybd/lsmt/index.h
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Expand Up @@ -149,6 +149,7 @@ class IComboIndex : public IMemoryIndex0 {
// backing index must NOT be IMemoryIndex0!
virtual int backing_index(const IMemoryIndex *bi) = 0;
virtual const IMemoryIndex *backing_index() const = 0;
virtual int front_index(const IMemoryIndex0 *fi) = 0;
virtual const IMemoryIndex0 *front_index() const = 0;

// dump index0 which needs to compact
Expand Down
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