int SLNSessionGetValueForField(SLNSessionRef const session, str_t value[], size_t const max, strarg_t const fileURI, strarg_t const field) {
if(!SLNSessionHasPermission(session, SLN_RDONLY)) return DB_EACCES;
if(!field) return DB_EINVAL;
if(max) value[0] = '\0';
int rc = 0;
DB_cursor *metafiles = NULL;
DB_cursor *values = NULL;
SLNRepoRef const repo = SLNSessionGetRepo(session);
DB_env *db = NULL;
SLNRepoDBOpen(repo, &db);
DB_txn *txn = NULL;
rc = db_txn_begin(db, NULL, DB_RDONLY, &txn);
if(rc < 0) goto done;
rc = db_cursor_open(txn, &metafiles);
if(rc < 0) goto done;
rc = db_cursor_open(txn, &values);
if(rc < 0) goto done;
DB_range metaFileIDs[1];
SLNTargetURIAndMetaFileIDRange1(metaFileIDs, txn, fileURI);
DB_val metaFileID_key[1];
rc = db_cursor_firstr(metafiles, metaFileIDs, metaFileID_key, NULL, +1);
if(rc < 0 && DB_NOTFOUND != rc) goto done;
for(; rc >= 0; rc = db_cursor_nextr(metafiles, metaFileIDs, metaFileID_key, NULL, +1)) {
strarg_t u;
uint64_t metaFileID;
SLNTargetURIAndMetaFileIDKeyUnpack(metaFileID_key, txn, &u, &metaFileID);
assert(0 == strcmp(fileURI, u));
DB_range vrange[1];
SLNMetaFileIDFieldAndValueRange2(vrange, txn, metaFileID, field);
DB_val value_val[1];
rc = db_cursor_firstr(values, vrange, value_val, NULL, +1);
if(rc < 0 && DB_NOTFOUND != rc) goto done;
for(; rc >= 0; rc = db_cursor_nextr(values, vrange, value_val, NULL, +1)) {
uint64_t m;
strarg_t f, v;
SLNMetaFileIDFieldAndValueKeyUnpack(value_val, txn, &m, &f, &v);
assert(metaFileID == m);
assert(0 == strcmp(field, f));
if(!v) continue;
if(0 == strcmp("", v)) continue;
size_t const len = strlen(v);
memcpy(value, v, MIN(len, max-1));
value[MIN(len, max-1)] = '\0';
goto done;
}
}
done:
db_cursor_close(values); values = NULL;
db_cursor_close(metafiles); metafiles = NULL;
db_txn_abort(txn); txn = NULL;
SLNRepoDBClose(repo, &db);
return rc;
}
int SLNSessionGetValueForField(SLNSessionRef const session, DB_txn *const txn, strarg_t const fileURI, strarg_t const field, str_t *out, size_t const max) {
int rc = 0;
DB_cursor *metafiles = NULL;
DB_cursor *values = NULL;
rc = db_cursor_open(txn, &metafiles);
if(rc < 0) goto done;
rc = db_cursor_open(txn, &values);
if(rc < 0) goto done;
DB_range metaFileIDs[1];
SLNTargetURIAndMetaFileIDRange1(metaFileIDs, txn, fileURI);
DB_val metaFileID_key[1];
rc = db_cursor_firstr(metafiles, metaFileIDs, metaFileID_key, NULL, +1);
if(rc < 0 && DB_NOTFOUND != rc) goto done;
for(; rc >= 0; rc = db_cursor_nextr(metafiles, metaFileIDs, metaFileID_key, NULL, +1)) {
strarg_t u;
uint64_t metaFileID;
SLNTargetURIAndMetaFileIDKeyUnpack(metaFileID_key, txn, &u, &metaFileID);
assert(0 == strcmp(fileURI, u));
DB_range vrange[1];
SLNMetaFileIDFieldAndValueRange2(vrange, txn, metaFileID, field);
DB_val value_val[1];
rc = db_cursor_firstr(values, vrange, value_val, NULL, +1);
if(rc < 0 && DB_NOTFOUND != rc) goto done;
for(; rc >= 0; rc = db_cursor_nextr(values, vrange, value_val, NULL, +1)) {
uint64_t m;
strarg_t f, v;
SLNMetaFileIDFieldAndValueKeyUnpack(value_val, txn, &m, &f, &v);
assert(metaFileID == m);
assert(0 == strcmp(field, f));
if(!v || '\0' == v[0]) continue;
strlcpy(out, v, max);
goto done;
}
}
done:
db_cursor_close(values); values = NULL;
db_cursor_close(metafiles); metafiles = NULL;
return rc;
}
static uint64_t add_metafile(DB_txn *const txn, uint64_t const fileID, strarg_t const targetURI) {
uint64_t const metaFileID = fileID;
uint64_t const latestMetaFileID = db_next_id(SLNMetaFileByID, txn);
if(metaFileID < latestMetaFileID) return 0;
// If it's not a new file, then it's not a new meta-file.
// Note that ordinary files can't be "promoted" to meta-files later
// because that would break the ordering.
DB_val null = { 0, NULL };
DB_cursor *cursor = NULL;
int rc = db_txn_cursor(txn, &cursor);
assert(rc >= 0);
DB_val metaFileID_key[1];
SLNMetaFileByIDKeyPack(metaFileID_key, txn, metaFileID);
DB_val metaFile_val[1];
SLNMetaFileByIDValPack(metaFile_val, txn, fileID, targetURI);
rc = db_put(txn, metaFileID_key, metaFile_val, DB_NOOVERWRITE_FAST);
assert(rc >= 0);
DB_range alts[1];
SLNTargetURIAndMetaFileIDRange1(alts, txn, targetURI);
rc = db_cursor_firstr(cursor, alts, NULL, NULL, +1);
assert(rc >= 0 || DB_NOTFOUND == rc);
if(DB_NOTFOUND == rc) {
DB_val unique[1];
SLNFirstUniqueMetaFileIDKeyPack(unique, txn, metaFileID);
rc = db_put(txn, unique, &null, DB_NOOVERWRITE_FAST);
assert(rc >= 0);
}
DB_val targetURI_key[1];
SLNTargetURIAndMetaFileIDKeyPack(targetURI_key, txn, targetURI, metaFileID);
rc = db_put(txn, targetURI_key, &null, DB_NOOVERWRITE_FAST);
assert(rc >= 0);
return metaFileID;
}
