feat(log): structured logging with comptime dispatch, aligned with logforth

Author: GrapeBaBa

build.zig

@@ -149,6 +149,23 @@ pub fn build(b: *std.Build) void {
     module_bls.linkLibrary(dep_blst.artifact("blst"));
     b.modules.put(b.dupe("bls"), module_bls) catch @panic("OOM");
 
+    const module_ring_buffer = b.createModule(.{
+        .root_source_file = b.path("src/ring_buffer.zig"),
+        .target = target,
+        .optimize = optimize,
+    });
+    b.modules.put(b.dupe("ring_buffer"), module_ring_buffer) catch @panic("OOM");
+
+    const module_log = b.createModule(.{
+        .root_source_file = b.path("src/log/root.zig"),
+        .target = target,
+        .optimize = optimize,
+        .imports = &.{
+            .{ .name = "ring_buffer", .module = module_ring_buffer },
+        },
+    });
+    b.modules.put(b.dupe("log"), module_log) catch @panic("OOM");
+
     const module_state_transition = b.createModule(.{
         .root_source_file = b.path("src/state_transition/root.zig"),
         .target = target,
@@ -202,6 +219,29 @@ pub fn build(b: *std.Build) void {
     const tls_run_exe_metrics_stf = b.step("run:metrics_stf", "Run the metrics_stf executable");
     tls_run_exe_metrics_stf.dependOn(&run_exe_metrics_stf.step);
 
+    const module_log_smoke = b.createModule(.{
+        .root_source_file = b.path("examples/log_smoke.zig"),
+        .target = target,
+        .optimize = optimize,
+    });
+    b.modules.put(b.dupe("log_smoke"), module_log_smoke) catch @panic("OOM");
+
+    const exe_log_smoke = b.addExecutable(.{
+        .name = "log_smoke",
+        .root_module = module_log_smoke,
+    });
+
+    const install_exe_log_smoke = b.addInstallArtifact(exe_log_smoke, .{});
+
+    const tls_install_exe_log_smoke = b.step("build-exe:log_smoke", "Install the log_smoke executable");
+    tls_install_exe_log_smoke.dependOn(&install_exe_log_smoke.step);
+    b.getInstallStep().dependOn(&install_exe_log_smoke.step);
+
+    const run_exe_log_smoke = b.addRunArtifact(exe_log_smoke);
+    if (b.args) |args| run_exe_log_smoke.addArgs(args);
+    const tls_run_exe_log_smoke = b.step("run:log_smoke", "Run the log_smoke executable");
+    tls_run_exe_log_smoke.dependOn(&run_exe_log_smoke.step);
+
     const module_download_spec_tests = b.createModule(.{
         .root_source_file = b.path("test/spec/download_spec_tests.zig"),
         .target = target,
@@ -681,6 +721,20 @@ pub fn build(b: *std.Build) void {
     tls_run_test_bls.dependOn(&run_test_bls.step);
     tls_run_test.dependOn(&run_test_bls.step);
 
+    const test_log = b.addTest(.{
+        .name = "log",
+        .root_module = module_log,
+        .filters = b.option([][]const u8, "log.filters", "log test filters") orelse &[_][]const u8{},
+    });
+    const install_test_log = b.addInstallArtifact(test_log, .{});
+    const tls_install_test_log = b.step("build-test:log", "Install the log test");
+    tls_install_test_log.dependOn(&install_test_log.step);
+
+    const run_test_log = b.addRunArtifact(test_log);
+    const tls_run_test_log = b.step("test:log", "Run the log test");
+    tls_run_test_log.dependOn(&run_test_log.step);
+    tls_run_test.dependOn(&run_test_log.step);
+
     const test_state_transition = b.addTest(.{
         .name = "state_transition",
         .root_module = module_state_transition,
@@ -723,6 +777,20 @@ pub fn build(b: *std.Build) void {
     tls_run_test_metrics_stf.dependOn(&run_test_metrics_stf.step);
     tls_run_test.dependOn(&run_test_metrics_stf.step);
 
+    const test_log_smoke = b.addTest(.{
+        .name = "log_smoke",
+        .root_module = module_log_smoke,
+        .filters = b.option([][]const u8, "log_smoke.filters", "log_smoke test filters") orelse &[_][]const u8{},
+    });
+    const install_test_log_smoke = b.addInstallArtifact(test_log_smoke, .{});
+    const tls_install_test_log_smoke = b.step("build-test:log_smoke", "Install the log_smoke test");
+    tls_install_test_log_smoke.dependOn(&install_test_log_smoke.step);
+
+    const run_test_log_smoke = b.addRunArtifact(test_log_smoke);
+    const tls_run_test_log_smoke = b.step("test:log_smoke", "Run the log_smoke test");
+    tls_run_test_log_smoke.dependOn(&run_test_log_smoke.step);
+    tls_run_test.dependOn(&run_test_log_smoke.step);
+
     const test_download_spec_tests = b.addTest(.{
         .name = "download_spec_tests",
         .root_module = module_download_spec_tests,
@@ -1088,6 +1156,9 @@ pub fn build(b: *std.Build) void {
     module_metrics_stf.addImport("config", module_config);
     module_metrics_stf.addImport("preset", module_preset);
     module_metrics_stf.addImport("httpz", dep_httpz.module("httpz"));
+    module_metrics_stf.addImport("log", module_log);
+
+    module_log_smoke.addImport("log", module_log);
 
     module_download_spec_tests.addImport("spec_test_options", options_module_spec_test_options);
 

examples/log_smoke.zig

@@ -0,0 +1,153 @@
+//! Log integration smoke example.
+//!
+//! Demonstrates the V2 structured Logger API, std.log bridge,
+//! all three async builder configs, and all three layout formats.
+//!
+//! Run:
+//!   zig build run:log_smoke
+//!
+//! Expected output: structured log lines on stderr from each dispatcher/layout.
+
+const std = @import("std");
+const log_mod = @import("log");
+
+/// Re-export std_options so std.log calls route through the V2 pipeline.
+pub const std_options = log_mod.std_options;
+
+const Logger = log_mod.Logger;
+const Attr = log_mod.Attr;
+const Dispatch = log_mod.Dispatch;
+const Dispatcher = log_mod.Dispatcher;
+const LevelFilter = log_mod.LevelFilter;
+const FlushableWriter = log_mod.FlushableWriter;
+const WriterAppend = log_mod.WriterAppend;
+const TextLayout = log_mod.TextLayout;
+const JsonLayout = log_mod.JsonLayout;
+const LogfmtLayout = log_mod.LogfmtLayout;
+
+/// Helper: emit a standard set of log lines through `log`.
+fn emitSample(log: anytype) void {
+    log.err("error msg", .{ .code = @as(u64, 500) });
+    log.warn("warn msg", .{});
+    log.info("info msg", .{ .slot = @as(u64, 42) });
+    log.debug("debug msg", .{ .flag = true });
+}
+
+pub fn main() !void {
+    var gpa = std.heap.GeneralPurposeAllocator(.{}){};
+    defer _ = gpa.deinit();
+    const allocator = gpa.allocator();
+
+    // ── 1. Default (sync stderr, TextLayout) ─────────────────
+
+    std.debug.print("\n=== 1. Default (sync stderr, TextLayout) ===\n", .{});
+    {
+        const std_log = std.log.scoped(.smoke);
+        std_log.err("std.log bridge err", .{});
+        std_log.info("std.log bridge info", .{});
+
+        const log = Logger(4).init(.smoke, log_mod.getGlobalDispatcher());
+        emitSample(log);
+
+        const child = log.with(&[_]Attr{Attr.str("module", "fc")});
+        child.info("child log", .{ .epoch = @as(u64, 7) });
+    }
+
+    // ── 2. Console builder (async stderr, TextLayout) ────────
+
+    std.debug.print("\n=== 2. Console builder (async stderr, TextLayout) ===\n", .{});
+    {
+        try log_mod.initConsoleDispatcher(allocator, .{ .min_level = .debug });
+        defer log_mod.deinitGlobalDispatcher();
+
+        const log = Logger(4).init(.smoke, log_mod.getGlobalDispatcher());
+        emitSample(log);
+        log_mod.flushGlobalDispatcher();
+    }
+
+    // ── 3. File builder (async rolling file, TextLayout) ─────
+
+    std.debug.print("\n=== 3. File builder (async rolling file, TextLayout) ===\n", .{});
+    {
+        try log_mod.initFileDispatcher(allocator, .{
+            .min_level = .debug,
+            .dir = std.fs.cwd(),
+            .base_name = "smoke.log",
+            .rolling = .{ .rotation = .never, .max_bytes = 1024 * 1024 },
+        });
+        defer log_mod.deinitGlobalDispatcher();
+
+        const log = Logger(4).init(.smoke, log_mod.getGlobalDispatcher());
+        emitSample(log);
+        log_mod.flushGlobalDispatcher();
+        std.debug.print("  → wrote smoke.log\n", .{});
+    }
+
+    // ── 4. Combined builder (async stderr + file, TextLayout) ─
+
+    std.debug.print("\n=== 4. Combined builder (async stderr + file, TextLayout) ===\n", .{});
+    {
+        try log_mod.initCombinedDispatcher(allocator, .{
+            .min_level = .debug,
+            .dir = std.fs.cwd(),
+            .base_name = "smoke_combined.log",
+            .rolling = .{ .rotation = .never, .max_bytes = 1024 * 1024 },
+        });
+        defer log_mod.deinitGlobalDispatcher();
+
+        const log = Logger(4).init(.smoke, log_mod.getGlobalDispatcher());
+        emitSample(log);
+        log_mod.flushGlobalDispatcher();
+        std.debug.print("  → wrote smoke_combined.log\n", .{});
+    }
+
+    // ── 5. Custom pipeline — JsonLayout (sync stderr) ────────
+
+    std.debug.print("\n=== 5. JsonLayout (sync stderr) ===\n", .{});
+    {
+        const WA = WriterAppend(JsonLayout);
+        const D = Dispatch(struct { LevelFilter }, struct {}, struct { WA });
+        const Disp = Dispatcher(struct { D });
+
+        var dispatcher = Disp{
+            .dispatches = .{
+                D{
+                    .filters = .{LevelFilter.init(.debug)},
+                    .diagnostics = .{},
+                    .appenders = .{WA.init(allocator, JsonLayout{}, FlushableWriter.stderrWriter())},
+                },
+            },
+        };
+
+        const log = Logger(4).init(.smoke, dispatcher.any());
+        emitSample(log);
+    }
+
+    // ── 6. Custom pipeline — LogfmtLayout (sync stderr) ──────
+
+    std.debug.print("\n=== 6. LogfmtLayout (sync stderr) ===\n", .{});
+    {
+        const WA = WriterAppend(LogfmtLayout);
+        const D = Dispatch(struct { LevelFilter }, struct {}, struct { WA });
+        const Disp = Dispatcher(struct { D });
+
+        var dispatcher = Disp{
+            .dispatches = .{
+                D{
+                    .filters = .{LevelFilter.init(.debug)},
+                    .diagnostics = .{},
+                    .appenders = .{WA.init(allocator, LogfmtLayout{}, FlushableWriter.stderrWriter())},
+                },
+            },
+        };
+
+        const log = Logger(4).init(.smoke, dispatcher.any());
+        emitSample(log);
+    }
+
+    // cleanup generated files
+    std.fs.cwd().deleteFile("smoke.log") catch {};
+    std.fs.cwd().deleteFile("smoke_combined.log") catch {};
+
+    std.debug.print("\n=== All 6 configurations OK ===\n", .{});
+}