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Migrate jsonpull to unique_ptr ownership

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Replaces the shared_ptr-based json_object_ptr with a unique_ptr that
has a stateless custom deleter dispatching on json_object::type before
calling the right subclass destructor. Eliminates per-node atomic
reference-counting and the control-block allocation that shared_ptr
required for every node in the tree.

API now distinguishes owning and borrowing pointers explicitly:
- json_read / json_read_separators / json_hash_get return raw
  json_object * (borrowed from the parser-owned tree).
- json_read_tree / json_disconnect return json_object_ptr (caller
  takes ownership; back-pointers are cleared so the subtree can
  outlive the parser).
- json_free / json_context / json_stringify take raw pointers.
- The parser's container_stack holds raw pointers; jp->root keeps
  unique_ptr ownership of the most recent top-level value.

Internally, take_from_owner moves the unique_ptr out of whichever
parent vector / hash entry / parser root owned it, which both
json_free and json_disconnect rely on.

In the streaming parsers (parse_feature, parse_layers, the
geojson-loop callback), we are careful to free `j` only after we
have processed a complete Feature: json_read returns each token
as the tree is being built up, and freeing an intermediate node
would splice it out of the surrounding hash and corrupt the
in-progress feature.

Benchmark (tl_2022_us_county.json, -z0 --extend-zooms-if-still-dropping,
median of 5 runs on macOS arm64): 8.5s, vs 10.6s with shared_ptr
and 8.7s on the pre-refactor C baseline.

Co-authored-by: Cursor <cursoragent@cursor.com>
This commit is contained in:
Erica Fischer
2026-05-30 20:44:25 -07:00
co-authored by Cursor
parent 1a7075e3ab
commit 65beb3f0d7
23 changed files with 408 additions and 289 deletions
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pmtiles_file.cpp
+4 -4
View File
@@ -422,21 +422,21 @@ sqlite3 *pmtilesmeta2tmp(const char *fname, const char *pmtiles_map) {
state.nospace = true;
state.json_write_string("vector_layers");
state.nospace = true;
state.json_write_json(json_stringify(e.value));
state.json_write_json(json_stringify(e.value.get()));
} else if (key == "tilestats" && e.value->type == JSON_HASH) {
has_json = true;
state.nospace = true;
state.json_write_string("tilestats");
state.nospace = true;
state.json_write_json(json_stringify(e.value));
state.json_write_json(json_stringify(e.value.get()));
} else if (key == "strategies" && e.value->type == JSON_ARRAY) {
sql = sqlite3_mprintf("INSERT INTO metadata (name, value) VALUES ('strategies', %Q);", json_stringify(e.value).c_str());
sql = sqlite3_mprintf("INSERT INTO metadata (name, value) VALUES ('strategies', %Q);", json_stringify(e.value.get()).c_str());
if (sqlite3_exec(db, sql, NULL, NULL, &err) != SQLITE_OK) {
fprintf(stderr, "set %s in metadata: %s\n", key.c_str(), err);
}
sqlite3_free(sql);
} else if (key == "tippecanoe_decisions" && e.value->type == JSON_HASH) {
sql = sqlite3_mprintf("INSERT INTO metadata (name, value) VALUES ('tippecanoe_decisions', %Q);", json_stringify(e.value).c_str());
sql = sqlite3_mprintf("INSERT INTO metadata (name, value) VALUES ('tippecanoe_decisions', %Q);", json_stringify(e.value.get()).c_str());
if (sqlite3_exec(db, sql, NULL, NULL, &err) != SQLITE_OK) {
fprintf(stderr, "set %s in metadata: %s\n", key.c_str(), err);
}