ifcviewer: v16 zstd-compressed sidecars (~10x smaller over the wire)

The .ifcview data is hugely redundant (repeated double instance matrices, patterned indices) — measured 12x zstd whole-file. Server Content-Encoding can't be used (it breaks HTTP Range), so compress PER-CHUNK into the format. Format (v16): geometry becomes per-chunk zstd(vertices)+zstd(indices) frames — each independently Range-fetchable, so streaming is intact — and the critical + deferred metadata blocks are single zstd frames. SidecarChunk carries the compressed blob offsets/sizes; applyStreamedChunk (render/upload) is UNCHANGED — decompression slots into the fetch. Full readSidecar (test/tooling) reconstructs by decompress+scatter. zstd: desktop links libzstd (also compresses at bake); the web build (Emscripten has no zstd port) FetchContent's the pinned zstd source and compiles its decompress-only subset for wasm — no vendored blob, same version as desktop. New SidecarCompress wraps it (compress guarded off under Emscripten). Both stream paths — desktop StreamingThread worker + sync fallback (readChunkGeometryCompressed) and web beginWebChunkLoad — decompress; readSidecarMetadataOnly / the web bootstrap / loadDeferredMetadataWeb decompress the metadata blocks. streamingByteProgress reports COMPRESSED bytes. MEASURED: a 752 MB v15 federation → 75 MB v16 (10x; per-file 6.7-15.3x); PP-PLP 118→15 MB, loads 13/13 chunks on web, 0 errors. Three fixes found while testing big federations on a real server: - Web-streamed race: streaming_from_web was set in the deferred-header callback (a round-trip after the model+chunks exist), so driveStreamingLoads could take the sync fopen path meanwhile → "failed to read/decompress chunk 0". Now set immediately after applyCachedModel. - OOM abort on 18 models: the pool grew unbounded until an alloc failed, but on web that's an uncatchable bad_alloc abort. Cap total pool capacity (setMaxTotalCapacity, 3 GB) so it stops before the heap ceiling, and raise MAXIMUM_MEMORY 2→4 GB (wasm32 max) for headroom. - Web never evicted (grow-or-block only). At the hard budget, fall through to the LRU/priority evictor so a big federation stays navigable (highest-contribution chunks win) instead of freezing with holes. 113/113 desktop + 6/6 web smoke pass. No back-compat: regenerate sidecars (desktop bakes v16; scratch conv tool migrates v15→v16). Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
2026-08-19 19:54:07 +00:00 · 2026-07-02 10:24:59 +10:00
parent 5299f6c13c
commit 0b8c787ac0
19 changed files with 862 additions and 442 deletions
@@ -0,0 +1,46 @@
+/********************************************************************************
+ *                                                                              *
+ * This file is part of IfcOpenShell.                                           *
+ *                                                                              *
+ * IfcOpenShell is free software: you can redistribute it and/or modify         *
+ * it under the terms of the Lesser GNU General Public License as published by  *
+ * the Free Software Foundation, either version 3.0 of the License, or          *
+ * (at your option) any later version.                                          *
+ *                                                                              *
+ * IfcOpenShell is distributed in the hope that it will be useful,              *
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of               *
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the                 *
+ * Lesser GNU General Public License for more details.                          *
+ *                                                                              *
+ * You should have received a copy of the Lesser GNU General Public License     *
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.         *
+ *                                                                              *
+ ********************************************************************************/
+
+#include "SidecarCompress.h"
+
+#include <zstd.h>
+
+namespace SidecarCompress {
+
+bool decompress(const std::uint8_t* src, std::size_t src_size,
+                std::uint8_t* dst, std::size_t raw_size) {
+    if (raw_size == 0) return src_size == 0;  // empty in ↔ empty out
+    if (!src || !dst || src_size == 0) return false;
+    const size_t got = ZSTD_decompress(dst, raw_size, src, src_size);
+    return !ZSTD_isError(got) && got == raw_size;
+}
+
+#if !defined(__EMSCRIPTEN__)
+std::vector<std::uint8_t> compress(const std::uint8_t* src, std::size_t n,
+                                   int level) {
+    if (n == 0) return {};
+    std::vector<std::uint8_t> out(ZSTD_compressBound(n));
+    const size_t got = ZSTD_compress(out.data(), out.size(), src, n, level);
+    if (ZSTD_isError(got)) return {};
+    out.resize(got);
+    return out;
+}
+#endif
+
+}  // namespace SidecarCompress