atproto utils for zig
zat.dev
atproto
sdk
zig
add benchmarks for low-level buffer-direct API
Measures writeText, writeUint, writeCidLink, writeRecord (manual 434-byte
record), readText, readUint, readCidLink, skipValue, peekType. Uses
runtime-opaque inputs and keeps output buffers alive to prevent dead
store elimination. Key result: manual record write via low-level API is
5 ns vs 124 ns for the Writer-based encoder (25x).
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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-7
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src/internal/repo/cbor_bench.zig
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src/internal/repo/cbor_bench.zig
···
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.{ .key = "text", .value = .{ .text = "Hello, world! This is a test post with some content." } },
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} };
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const bench_text = "Hello, world! This is a test post with some content.";
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const bench_text_literal = "Hello, world! This is a test post with some content.";
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// pre-encoded data (initialized in main)
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// pre-encoded data (initialized at runtime in initBenchData so the compiler
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// cannot constant-fold through them — matches real production conditions
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// where inputs arrive from the network)
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var encoded_record: []const u8 = undefined;
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var encoded_text: []const u8 = undefined;
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var encoded_uint: []const u8 = undefined;
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var encoded_cid_link: []const u8 = undefined;
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var bench_cid: Cid = undefined;
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var bench_arena: std.heap.ArenaAllocator = undefined;
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// runtime-opaque text for write benchmarks (same content as bench_text_literal
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// but not visible to the optimizer as a comptime constant)
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var bench_text: []const u8 = undefined;
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// CAR benchmark data
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var car_bytes: []const u8 = undefined;
···
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const alloc = bench_arena.allocator();
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encoded_record = cbor.encodeAlloc(alloc, bench_record) catch @panic("encode record");
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bench_text = alloc.dupe(u8, bench_text_literal) catch @panic("dupe text");
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encoded_text = cbor.encodeAlloc(alloc, .{ .text = bench_text }) catch @panic("encode text");
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encoded_uint = cbor.encodeAlloc(alloc, .{ .unsigned = 1_234_567_890 }) catch @panic("encode uint");
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bench_cid = Cid.forDagCbor(alloc, encoded_record) catch @panic("compute cid");
···
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fn benchWriteTextDirect() void {
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var buf: [128]u8 = undefined;
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const end = cbor.writeText(&buf, 0, bench_text);
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std.mem.doNotOptimizeAway(end);
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std.mem.doNotOptimizeAway(buf[0..end]);
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}
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fn benchWriteUintDirect() void {
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var buf: [16]u8 = undefined;
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const end = cbor.writeUint(&buf, 0, 1_234_567_890);
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std.mem.doNotOptimizeAway(end);
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std.mem.doNotOptimizeAway(buf[0..end]);
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}
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fn benchWriteCidLinkDirect() void {
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var buf: [128]u8 = undefined;
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const end = cbor.writeCidLink(&buf, 0, bench_cid.raw);
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std.mem.doNotOptimizeAway(end);
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std.mem.doNotOptimizeAway(buf[0..end]);
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}
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fn benchWriteRecordDirect() void {
···
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p = cbor.writeMapHeader(&buf, p, 5);
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// keys in DAG-CBOR order: text(4), $type(5), langs(5), reply(5), createdAt(9)
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p = cbor.writeText(&buf, p, "text");
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p = cbor.writeText(&buf, p, "Hello, world! This is a test post with some content.");
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p = cbor.writeText(&buf, p, bench_text);
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p = cbor.writeText(&buf, p, "$type");
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p = cbor.writeText(&buf, p, "app.bsky.feed.post");
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p = cbor.writeText(&buf, p, "langs");
···
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p = cbor.writeText(&buf, p, "at://did:plc:4nendwqrs754gt6qvgr56jmn/app.bsky.feed.post/3medg2qvcuc2c");
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p = cbor.writeText(&buf, p, "createdAt");
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p = cbor.writeText(&buf, p, "2024-01-15T12:00:00.000Z");
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std.mem.doNotOptimizeAway(p);
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std.mem.doNotOptimizeAway(buf[0..p]);
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}
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// --- low-level read (buffer-direct) ---