fix(prometheus): remove httpz again and fix prometheus metrics (#555)

* Revert "fix(prometheus): prometheus cannot connect to sig's metrics (#531)"

This reverts commit 3e0043e.

* prometheus: use HTTP 1.1 instead of 1.0

build.zig

@@ -49,9 +49,6 @@ pub fn build(b: *Build) void {
     const zig_cli_dep = b.dependency("zig-cli", dep_opts);
     const zig_cli_mod = zig_cli_dep.module("zig-cli");
 
-    const httpz_dep = b.dependency("httpz", dep_opts);
-    const httpz_mod = httpz_dep.module("httpz");
-
     const zstd_dep = b.dependency("zstd", dep_opts);
     const zstd_mod = zstd_dep.module("zstd");
 
@@ -80,7 +77,6 @@ pub fn build(b: *Build) void {
     sig_mod.addImport("zig-network", zig_network_mod);
     sig_mod.addImport("base58", base58_mod);
     sig_mod.addImport("zig-cli", zig_cli_mod);
-    sig_mod.addImport("httpz", httpz_mod);
     sig_mod.addImport("zstd", zstd_mod);
     switch (blockstore_db) {
         .rocksdb => sig_mod.addImport("rocksdb", rocksdb_mod),
@@ -108,7 +104,6 @@ pub fn build(b: *Build) void {
 
     sig_exe.root_module.addImport("xev", xev_mod);
     sig_exe.root_module.addImport("base58", base58_mod);
-    sig_exe.root_module.addImport("httpz", httpz_mod);
     sig_exe.root_module.addImport("zig-cli", zig_cli_mod);
     sig_exe.root_module.addImport("zig-network", zig_network_mod);
     sig_exe.root_module.addImport("zstd", zstd_mod);
@@ -148,7 +143,6 @@ pub fn build(b: *Build) void {
 
     unit_tests_exe.root_module.addImport("xev", xev_mod);
     unit_tests_exe.root_module.addImport("base58", base58_mod);
-    unit_tests_exe.root_module.addImport("httpz", httpz_mod);
     unit_tests_exe.root_module.addImport("zig-network", zig_network_mod);
     unit_tests_exe.root_module.addImport("zstd", zstd_mod);
     switch (blockstore_db) {
@@ -184,7 +178,6 @@ pub fn build(b: *Build) void {
     fuzz_exe.root_module.addImport("xev", xev_mod);
     fuzz_exe.root_module.addImport("base58", base58_mod);
     fuzz_exe.root_module.addImport("zig-network", zig_network_mod);
-    fuzz_exe.root_module.addImport("httpz", httpz_mod);
     fuzz_exe.root_module.addImport("zstd", zstd_mod);
     switch (blockstore_db) {
         .rocksdb => fuzz_exe.root_module.addImport("rocksdb", rocksdb_mod),
@@ -220,7 +213,6 @@ pub fn build(b: *Build) void {
     benchmark_exe.root_module.addImport("xev", xev_mod);
     benchmark_exe.root_module.addImport("base58", base58_mod);
     benchmark_exe.root_module.addImport("zig-network", zig_network_mod);
-    benchmark_exe.root_module.addImport("httpz", httpz_mod);
     benchmark_exe.root_module.addImport("zstd", zstd_mod);
     benchmark_exe.root_module.addImport("prettytable", pretty_table_mod);
     switch (blockstore_db) {

build.zig.zon

@@ -15,10 +15,6 @@
             .url = "https://github.com/sam701/zig-cli/archive/8c7a798c0f7fa0358d7ab41106fc872fca4cd995.tar.gz",
             .hash = "1220c008492d9460c3be2b209600a948181e6efb3bf0d79a1633def499632e708f4b",
         },
-        .httpz = .{
-            .url = "https://github.com/karlseguin/http.zig/archive/79dad0f0cc652830cd8e49bf3e73aa77155ad4b2.tar.gz",
-            .hash = "1220b8a918dfcee4fc8326ec337776e2ffd3029511c35f6b96d10aa7be98ca2faf99",
-        },
         .zstd = .{
             .url = "git+https://github.com/Syndica/zstd.zig#5095f011c1183aa67d696172795440d6a33732c9",
             .hash = "122030ebe280b73693963a67ed656226a67b7f00a0a05665155da00c9fcdee90de88",

src/prometheus/http.zig

@@ -1,48 +1,77 @@
+const builtin = @import("builtin");
 const std = @import("std");
-const httpz = @import("httpz");
 
 const Registry = @import("registry.zig").Registry;
 const globalRegistry = @import("registry.zig").globalRegistry;
 const DEFAULT_BUCKETS = @import("histogram.zig").DEFAULT_BUCKETS;
 
+/// Initializes the global registry. Returns error if registry was already initialized.
+/// Spawns a thread to serve the metrics over http on the given port.
+pub fn spawnMetrics(
+    gpa_allocator: std.mem.Allocator,
+    port: u16,
+) !std.Thread {
+    const registry = globalRegistry();
+    return std.Thread.spawn(.{}, servePrometheus, .{ gpa_allocator, registry, port });
+}
+
 pub fn servePrometheus(
     allocator: std.mem.Allocator,
     registry: *Registry(.{}),
     port: u16,
 ) !void {
-    const endpoint = MetricsEndpoint{
-        .allocator = allocator,
-        .registry = registry,
-    };
-    var server = try httpz.ServerCtx(*const MetricsEndpoint, *const MetricsEndpoint).init(
-        allocator,
-        .{ .port = port, .address = "0.0.0.0" },
-        &endpoint,
-    );
-    var router = server.router();
-    router.get("/metrics", getMetrics);
-    return server.listen();
-}
+    const our_ip = std.net.Address.initIp4(.{ 0, 0, 0, 0 }, port);
+    var tcp = try our_ip.listen(.{
+        .force_nonblocking = true,
+        .reuse_address = true,
+    });
+    defer tcp.deinit();
 
-const MetricsEndpoint = struct {
-    allocator: std.mem.Allocator,
-    registry: *Registry(.{}),
-};
+    while (true) {
+        const conn = tcp.accept() catch |err| switch (err) {
+            error.WouldBlock => continue,
+            else => |e| return e,
+        };
 
-/// Initializes the global registry. Returns error if registry was already initialized.
-/// Spawns a thread to serve the metrics over http on the given port.
-pub fn spawnMetrics(gpa_allocator: std.mem.Allocator, port: u16) !std.Thread {
-    const registry = globalRegistry();
-    return std.Thread.spawn(.{}, servePrometheus, .{ gpa_allocator, registry, port });
-}
+        // TODO: unify this with the code for the RPC server
+        if (comptime builtin.target.isDarwin()) set_flags: {
+            const FlagsInt = @typeInfo(std.posix.O).Struct.backing_integer.?;
+            var flags_int: FlagsInt =
+                @intCast(try std.posix.fcntl(conn.stream.handle, std.posix.F.GETFL, 0));
+            const flags: *std.posix.O =
+                std.mem.bytesAsValue(std.posix.O, std.mem.asBytes(&flags_int));
+            if (flags.NONBLOCK == false and flags.CLOEXEC == true) break :set_flags;
+            flags.NONBLOCK = false;
+            flags.CLOEXEC = true;
+            _ = try std.posix.fcntl(conn.stream.handle, std.posix.F.SETFL, flags_int);
+        }
 
-pub fn getMetrics(
-    self: *const MetricsEndpoint,
-    _: *httpz.Request,
-    response: *httpz.Response,
-) !void {
-    response.content_type = .TEXT; // expected by prometheus
-    try self.registry.write(self.allocator, response.writer());
+        var read_buffer: [4096]u8 = undefined;
+        var http_server = std.http.Server.init(conn, &read_buffer);
+        var request = http_server.receiveHead() catch continue;
+
+        if (request.head.method != .GET or
+            !std.mem.eql(u8, request.head.target, "/metrics") //
+        ) {
+            try request.respond("", .{
+                .status = .not_found,
+                .keep_alive = false,
+            });
+            continue;
+        }
+
+        var send_buffer: [4096]u8 = undefined;
+        var response = request.respondStreaming(.{
+            .send_buffer = &send_buffer,
+            .respond_options = .{
+                .status = .ok,
+                .keep_alive = true,
+                .extra_headers = &.{.{ .name = "Content-Type", .value = "text/plain" }},
+            },
+        });
+        try registry.write(allocator, response.writer());
+        try response.end();
+    }
 }
 
 /// Runs a test prometheus endpoint with dummy data.