From 19a117889c2db6b817af9458c04c04f324162e75 Mon Sep 17 00:00:00 2001
From: Stefan Boberg <stefan.boberg@epicgames.com>
Date: Mon, 9 Mar 2026 10:50:47 +0100
Subject: Eliminate spdlog dependency (#773)

Removes the vendored spdlog library (~12,000 lines) and replaces it with a purpose-built logging system in zencore (~1,800 lines). The new implementation provides the same functionality with fewer abstractions, no shared_ptr overhead, and full control over the logging pipeline.

### What changed

**New logging core in zencore/logging/:**
- LogMessage, Formatter, Sink, Logger, Registry - core abstractions matching spdlog's model but simplified
- AnsiColorStdoutSink - ANSI color console output (replaces spdlog stdout_color_sink)
- MsvcSink - OutputDebugString on Windows (replaces spdlog msvc_sink)
- AsyncSink - async logging via BlockingQueue worker thread (replaces spdlog async_logger)
- NullSink, MessageOnlyFormatter - utility types
- Thread-safe timestamp caching in formatters using RwLock

**Moved to zenutil/logging/:**
- FullFormatter - full log formatting with timestamp, logger name, level, source location, multiline alignment
- JsonFormatter - structured JSON log output
- RotatingFileSink - rotating file sink with atomic size tracking

**API changes:**
- Log levels are now an enum (LogLevel) instead of int, eliminating the zen::logging::level namespace
- LoggerRef no longer wraps shared_ptr - it holds a raw pointer with the registry owning lifetime
- Logger error handler is wired through Registry and propagated to all loggers on registration
- Logger::Log() now populates ThreadId on every message

**Cleanup:**
- Deleted thirdparty/spdlog/ entirely (110+ files)
- Deleted full_test_formatter (was ~80% duplicate of FullFormatter)
- Renamed snake_case classes to PascalCase (full_formatter -> FullFormatter, json_formatter -> JsonFormatter, sentry_sink -> SentrySink)
- Removed spdlog from xmake dependency graph

### Build / test impact

- zencore no longer depends on spdlog
- zenutil and zenvfs xmake.lua updated to drop spdlog dep
- zentelemetry xmake.lua updated to drop spdlog dep
- All existing tests pass, no test changes required beyond formatter class renames
---
 thirdparty/spdlog/tests/test_stopwatch.cpp | 42 ------------------------------
 1 file changed, 42 deletions(-)
 delete mode 100644 thirdparty/spdlog/tests/test_stopwatch.cpp

(limited to 'thirdparty/spdlog/tests/test_stopwatch.cpp')

diff --git a/thirdparty/spdlog/tests/test_stopwatch.cpp b/thirdparty/spdlog/tests/test_stopwatch.cpp
deleted file mode 100644
index b1b4b191c..000000000
--- a/thirdparty/spdlog/tests/test_stopwatch.cpp
+++ /dev/null
@@ -1,42 +0,0 @@
-#include "includes.h"
-#include "test_sink.h"
-#include "spdlog/stopwatch.h"
-
-TEST_CASE("stopwatch1", "[stopwatch]") {
-    using std::chrono::milliseconds;
-    using clock = std::chrono::steady_clock;
-    milliseconds wait_ms(500);
-    milliseconds tolerance_ms(250);
-    auto start = clock::now();
-    spdlog::stopwatch sw;
-    std::this_thread::sleep_for(wait_ms);
-    auto stop = clock::now();
-    auto diff_ms = std::chrono::duration_cast<milliseconds>(stop - start);
-    REQUIRE(sw.elapsed() >= diff_ms);
-    REQUIRE(sw.elapsed() <= diff_ms + tolerance_ms);
-}
-
-TEST_CASE("stopwatch2", "[stopwatch]") {
-    using spdlog::sinks::test_sink_st;
-    using std::chrono::duration_cast;
-    using std::chrono::milliseconds;
-    using clock = std::chrono::steady_clock;
-
-    clock::duration wait_duration(milliseconds(500));
-    clock::duration tolerance_duration(milliseconds(250));
-
-    auto test_sink = std::make_shared<test_sink_st>();
-
-    auto start = clock::now();
-    spdlog::stopwatch sw;
-    spdlog::logger logger("test-stopwatch", test_sink);
-    logger.set_pattern("%v");
-    std::this_thread::sleep_for(wait_duration);
-    auto stop = clock::now();
-    logger.info("{}", sw);
-    auto val = std::stod(test_sink->lines()[0]);
-    auto diff_duration = duration_cast<std::chrono::duration<double>>(stop - start);
-
-    REQUIRE(val >= (diff_duration).count() - 0.001);
-    REQUIRE(val <= (diff_duration + tolerance_duration).count());
-}
-- 
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