void
S_try_open_elements(void *context) {
struct try_open_elements_context *args
= (struct try_open_elements_context*)context;
PolyReader *self = args->self;
PolyReaderIVARS *const ivars = PolyReader_IVARS(self);
VArray *files = Snapshot_List(ivars->snapshot);
Folder *folder = PolyReader_Get_Folder(self);
uint32_t num_segs = 0;
uint64_t latest_schema_gen = 0;
CharBuf *schema_file = NULL;
// Find schema file, count segments.
for (uint32_t i = 0, max = VA_Get_Size(files); i < max; i++) {
CharBuf *entry = (CharBuf*)VA_Fetch(files, i);
if (Seg_valid_seg_name(entry)) {
num_segs++;
}
else if (CB_Starts_With_Str(entry, "schema_", 7)
&& CB_Ends_With_Str(entry, ".json", 5)
) {
uint64_t gen = IxFileNames_extract_gen(entry);
if (gen > latest_schema_gen) {
latest_schema_gen = gen;
if (!schema_file) { schema_file = CB_Clone(entry); }
else { CB_Mimic(schema_file, (Obj*)entry); }
}
}
}
// Read Schema.
if (!schema_file) {
DECREF(files);
THROW(ERR, "Can't find a schema file.");
}
else {
Hash *dump = (Hash*)Json_slurp_json(folder, schema_file);
if (dump) { // read file successfully
DECREF(ivars->schema);
ivars->schema = (Schema*)CERTIFY(
VTable_Load_Obj(SCHEMA, (Obj*)dump), SCHEMA);
DECREF(dump);
DECREF(schema_file);
schema_file = NULL;
}
else {
CharBuf *mess = MAKE_MESS("Failed to parse %o", schema_file);
DECREF(schema_file);
DECREF(files);
Err_throw_mess(ERR, mess);
}
}
VArray *segments = VA_new(num_segs);
for (uint32_t i = 0, max = VA_Get_Size(files); i < max; i++) {
CharBuf *entry = (CharBuf*)VA_Fetch(files, i);
// Create a Segment for each segmeta.
if (Seg_valid_seg_name(entry)) {
int64_t seg_num = IxFileNames_extract_gen(entry);
Segment *segment = Seg_new(seg_num);
// Bail if reading the file fails (probably because it's been
// deleted and a new snapshot file has been written so we need to
// retry).
if (Seg_Read_File(segment, folder)) {
VA_Push(segments, (Obj*)segment);
}
else {
CharBuf *mess = MAKE_MESS("Failed to read %o", entry);
DECREF(segment);
DECREF(segments);
DECREF(files);
Err_throw_mess(ERR, mess);
}
}
}
// Sort the segments by age.
VA_Sort(segments, NULL, NULL);
// Open individual SegReaders.
struct try_open_segreader_context seg_context;
seg_context.schema = PolyReader_Get_Schema(self);
seg_context.folder = folder;
seg_context.snapshot = PolyReader_Get_Snapshot(self);
seg_context.segments = segments;
seg_context.result = NULL;
args->seg_readers = VA_new(num_segs);
Err *error = NULL;
for (uint32_t seg_tick = 0; seg_tick < num_segs; seg_tick++) {
seg_context.seg_tick = seg_tick;
error = Err_trap(S_try_open_segreader, &seg_context);
if (error) {
break;
}
VA_Push(args->seg_readers, (Obj*)seg_context.result);
seg_context.result = NULL;
}
DECREF(segments);
DECREF(files);
if (error) {
DECREF(args->seg_readers);
args->seg_readers = NULL;
RETHROW(error);
}
}
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;
}
