void
BGMerger_Prepare_Commit_IMP(BackgroundMerger *self) {
BackgroundMergerIVARS *const ivars = BGMerger_IVARS(self);
Vector *seg_readers = PolyReader_Get_Seg_Readers(ivars->polyreader);
uint32_t num_seg_readers = Vec_Get_Size(seg_readers);
uint32_t segs_merged = 0;
if (ivars->prepared) {
THROW(ERR, "Can't call Prepare_Commit() more than once");
}
// Maybe merge existing index data.
if (num_seg_readers) {
segs_merged = S_maybe_merge(self);
}
if (!segs_merged) {
// Nothing merged. Leave `needs_commit` false and bail out.
ivars->prepared = true;
return;
}
// Finish the segment and write a new snapshot file.
else {
Folder *folder = ivars->folder;
Snapshot *snapshot = ivars->snapshot;
// Write out new deletions.
if (DelWriter_Updated(ivars->del_writer)) {
// Only write out if they haven't all been applied.
if (segs_merged != num_seg_readers) {
DelWriter_Finish(ivars->del_writer);
}
}
// Finish the segment.
SegWriter_Finish(ivars->seg_writer);
// Grab the write lock.
S_obtain_write_lock(self);
if (!ivars->write_lock) {
RETHROW(INCREF(Err_get_error()));
}
// Write temporary snapshot file.
DECREF(ivars->snapfile);
String *snapfile = IxManager_Make_Snapshot_Filename(ivars->manager);
ivars->snapfile = Str_Cat_Trusted_Utf8(snapfile, ".temp", 5);
DECREF(snapfile);
Folder_Delete(folder, ivars->snapfile);
Snapshot_Write_File(snapshot, folder, ivars->snapfile);
// Determine whether the index has been updated while this background
// merge process was running.
String *start_snapfile
= Snapshot_Get_Path(PolyReader_Get_Snapshot(ivars->polyreader));
Snapshot *latest_snapshot
= Snapshot_Read_File(Snapshot_new(), ivars->folder, NULL);
String *latest_snapfile = Snapshot_Get_Path(latest_snapshot);
bool index_updated
= !Str_Equals(start_snapfile, (Obj*)latest_snapfile);
if (index_updated) {
/* See if new deletions have been applied since this
* background merge process started against any of the
* segments we just merged away. If that's true, we need to
* write another segment which applies the deletions against
* the new composite segment.
*/
S_merge_updated_deletions(self);
// Add the fresh content to our snapshot. (It's important to
// run this AFTER S_merge_updated_deletions, because otherwise
// we couldn't tell whether the deletion counts changed.)
Vector *files = Snapshot_List(latest_snapshot);
for (uint32_t i = 0, max = Vec_Get_Size(files); i < max; i++) {
String *file = (String*)Vec_Fetch(files, i);
if (Str_Starts_With_Utf8(file, "seg_", 4)) {
int64_t gen = (int64_t)IxFileNames_extract_gen(file);
if (gen > ivars->cutoff) {
Snapshot_Add_Entry(ivars->snapshot, file);
}
}
}
DECREF(files);
// Since the snapshot content has changed, we need to rewrite it.
Folder_Delete(folder, ivars->snapfile);
Snapshot_Write_File(snapshot, folder, ivars->snapfile);
}
DECREF(latest_snapshot);
ivars->needs_commit = true;
}
// Close reader, so that we can delete its files if appropriate.
PolyReader_Close(ivars->polyreader);
ivars->prepared = true;
}
static bool_t
S_maybe_merge(Indexer *self, VArray *seg_readers)
{
bool_t merge_happened = false;
uint32_t num_seg_readers = VA_Get_Size(seg_readers);
Lock *merge_lock = IxManager_Make_Merge_Lock(self->manager);
bool_t got_merge_lock = Lock_Obtain(merge_lock);
int64_t cutoff;
VArray *to_merge;
uint32_t i, max;
if (got_merge_lock) {
self->merge_lock = merge_lock;
cutoff = 0;
}
else {
// If something else holds the merge lock, don't interfere.
Hash *merge_data = IxManager_Read_Merge_Data(self->manager);
if (merge_data) {
Obj *cutoff_obj = Hash_Fetch_Str(merge_data, "cutoff", 6);
if (cutoff_obj) {
cutoff = Obj_To_I64(cutoff_obj);
}
else {
cutoff = I64_MAX;
}
DECREF(merge_data);
}
else {
cutoff = I64_MAX;
}
DECREF(merge_lock);
}
// Get a list of segments to recycle. Validate and confirm that there are
// no dupes in the list.
to_merge = IxManager_Recycle(self->manager, self->polyreader,
self->del_writer, cutoff, self->optimize);
{
Hash *seen = Hash_new(VA_Get_Size(to_merge));
for (i = 0, max = VA_Get_Size(to_merge); i < max; i++) {
SegReader *seg_reader = (SegReader*)CERTIFY(
VA_Fetch(to_merge, i), SEGREADER);
CharBuf *seg_name = SegReader_Get_Seg_Name(seg_reader);
if (Hash_Fetch(seen, (Obj*)seg_name)) {
DECREF(seen);
DECREF(to_merge);
THROW(ERR, "Recycle() tried to merge segment '%o' twice",
seg_name);
}
Hash_Store(seen, (Obj*)seg_name, INCREF(&EMPTY));
}
DECREF(seen);
}
// Consolidate segments if either sparse or optimizing forced.
for (i = 0, max = VA_Get_Size(to_merge); i < max; i++) {
SegReader *seg_reader = (SegReader*)VA_Fetch(to_merge, i);
int64_t seg_num = SegReader_Get_Seg_Num(seg_reader);
Matcher *deletions
= DelWriter_Seg_Deletions(self->del_writer, seg_reader);
I32Array *doc_map = DelWriter_Generate_Doc_Map(self->del_writer,
deletions, SegReader_Doc_Max(seg_reader),
(int32_t)Seg_Get_Count(self->segment)
);
if (seg_num <= cutoff) {
THROW(ERR, "Segment %o violates cutoff (%i64 <= %i64)",
SegReader_Get_Seg_Name(seg_reader), seg_num, cutoff);
}
SegWriter_Merge_Segment(self->seg_writer, seg_reader, doc_map);
merge_happened = true;
DECREF(deletions);
DECREF(doc_map);
}
// Write out new deletions.
if (DelWriter_Updated(self->del_writer)) {
// Only write out if they haven't all been applied.
if (VA_Get_Size(to_merge) != num_seg_readers) {
DelWriter_Finish(self->del_writer);
}
}
DECREF(to_merge);
return merge_happened;
}
static bool
S_merge_updated_deletions(BackgroundMerger *self) {
BackgroundMergerIVARS *const ivars = BGMerger_IVARS(self);
Hash *updated_deletions = NULL;
PolyReader *new_polyreader
= PolyReader_open((Obj*)ivars->folder, NULL, NULL);
Vector *new_seg_readers
= PolyReader_Get_Seg_Readers(new_polyreader);
Vector *old_seg_readers
= PolyReader_Get_Seg_Readers(ivars->polyreader);
Hash *new_segs = Hash_new(Vec_Get_Size(new_seg_readers));
for (uint32_t i = 0, max = Vec_Get_Size(new_seg_readers); i < max; i++) {
SegReader *seg_reader = (SegReader*)Vec_Fetch(new_seg_readers, i);
String *seg_name = SegReader_Get_Seg_Name(seg_reader);
Hash_Store(new_segs, seg_name, INCREF(seg_reader));
}
for (uint32_t i = 0, max = Vec_Get_Size(old_seg_readers); i < max; i++) {
SegReader *seg_reader = (SegReader*)Vec_Fetch(old_seg_readers, i);
String *seg_name = SegReader_Get_Seg_Name(seg_reader);
// If this segment was merged away...
if (Hash_Fetch(ivars->doc_maps, seg_name)) {
SegReader *new_seg_reader
= (SegReader*)CERTIFY(
Hash_Fetch(new_segs, seg_name),
SEGREADER);
int32_t old_del_count = SegReader_Del_Count(seg_reader);
int32_t new_del_count = SegReader_Del_Count(new_seg_reader);
// ... were any new deletions applied against it?
if (old_del_count != new_del_count) {
DeletionsReader *del_reader
= (DeletionsReader*)SegReader_Obtain(
new_seg_reader,
Class_Get_Name(DELETIONSREADER));
if (!updated_deletions) {
updated_deletions = Hash_new(max);
}
Hash_Store(updated_deletions, seg_name,
(Obj*)DelReader_Iterator(del_reader));
}
}
}
DECREF(new_polyreader);
DECREF(new_segs);
if (!updated_deletions) {
return false;
}
else {
PolyReader *merge_polyreader
= PolyReader_open((Obj*)ivars->folder, ivars->snapshot, NULL);
Vector *merge_seg_readers
= PolyReader_Get_Seg_Readers(merge_polyreader);
Snapshot *latest_snapshot
= Snapshot_Read_File(Snapshot_new(), ivars->folder, NULL);
int64_t new_seg_num
= IxManager_Highest_Seg_Num(ivars->manager, latest_snapshot) + 1;
Segment *new_segment = Seg_new(new_seg_num);
SegWriter *seg_writer = SegWriter_new(ivars->schema, ivars->snapshot,
new_segment, merge_polyreader);
DeletionsWriter *del_writer = SegWriter_Get_Del_Writer(seg_writer);
int64_t merge_seg_num = Seg_Get_Number(ivars->segment);
uint32_t seg_tick = INT32_MAX;
int32_t offset = INT32_MAX;
SegWriter_Prep_Seg_Dir(seg_writer);
for (uint32_t i = 0, max = Vec_Get_Size(merge_seg_readers); i < max; i++) {
SegReader *seg_reader
= (SegReader*)Vec_Fetch(merge_seg_readers, i);
if (SegReader_Get_Seg_Num(seg_reader) == merge_seg_num) {
I32Array *offsets = PolyReader_Offsets(merge_polyreader);
seg_tick = i;
offset = I32Arr_Get(offsets, seg_tick);
DECREF(offsets);
}
}
if (offset == INT32_MAX) { THROW(ERR, "Failed sanity check"); }
HashIterator *iter = HashIter_new(updated_deletions);
while (HashIter_Next(iter)) {
String *seg_name = HashIter_Get_Key(iter);
Matcher *deletions = (Matcher*)HashIter_Get_Value(iter);
I32Array *doc_map
= (I32Array*)CERTIFY(
Hash_Fetch(ivars->doc_maps, seg_name),
I32ARRAY);
int32_t del;
while (0 != (del = Matcher_Next(deletions))) {
// Find the slot where the deleted doc resides in the
// rewritten segment. If the doc was already deleted when we
// were merging, do nothing.
int32_t remapped = I32Arr_Get(doc_map, del);
if (remapped) {
// It's a new deletion, so carry it forward and zap it in
// the rewritten segment.
DelWriter_Delete_By_Doc_ID(del_writer, remapped + offset);
}
}
}
DECREF(iter);
// Finish the segment and clean up.
DelWriter_Finish(del_writer);
SegWriter_Finish(seg_writer);
DECREF(seg_writer);
DECREF(new_segment);
DECREF(latest_snapshot);
DECREF(merge_polyreader);
DECREF(updated_deletions);
}
return true;
}
