improvements in robustness, save output of iperf3 for later analysis

src/main.zig

@@ -155,7 +155,10 @@ pub fn main() !void {
     }
 
     while (true) {
-        iperf3_log.info("waiting for connection", .{});
+        iperf3_log.info("starting new iperf3", .{});
+
+        var arena = std.heap.ArenaAllocator.init(allocator);
+        defer arena.deinit();
 
         var c = std.process.Child.init(
             &[_][]const u8{
@@ -166,33 +169,61 @@ pub fn main() !void {
                 "--json",
                 "--one-off",
             },
-            allocator,
+            arena.child_allocator,
         );
         c.stdin_behavior = .Ignore;
         c.stdout_behavior = .Pipe;
-        c.stderr_behavior = .Ignore;
+        c.stderr_behavior = .Pipe;
         try c.spawn();
 
-        var reader = c.stdout.?.reader();
-        var token_reader = std.json.reader(allocator, reader);
+        var stdout = std.ArrayList(u8).init(arena.child_allocator);
+        var stderr = std.ArrayList(u8).init(arena.child_allocator);
 
-        var obj = try std.json.parseFromTokenSource(
+        iperf3_log.info("waiting for data", .{});
+
+        try c.collectOutput(&stdout, &stderr, 16384);
+
+        var filename_buf: [std.fs.MAX_PATH_BYTES]u8 = undefined;
+        var filename: []u8 = undefined;
+        var timestamp = std.time.nanoTimestamp();
+
+        filename = try std.fmt.bufPrint(&filename_buf, "/tmp/{d}-stdout.json", .{timestamp});
+        try std.fs.cwd().writeFile(filename, stdout.items);
+
+        filename = try std.fmt.bufPrint(&filename_buf, "/tmp/{d}-stderr.json", .{timestamp});
+        try std.fs.cwd().writeFile(filename, stderr.items);
+
+        // var token_reader = std.json.reader(allocator, reader);
+
+        var obj_or_err = std.json.parseFromSliceLeaky(
             iperf3.IPerfReturn,
-            allocator,
-            &token_reader,
+            arena.child_allocator,
+            stdout.items,
             .{},
         );
-        defer obj.deinit();
 
-        var line = std.ArrayList(u8).init(allocator);
-        try std.json.stringify(
-            obj.value,
-            .{
-                .emit_null_optional_fields = false,
-            },
-            line.writer(),
-        );
-        defer line.deinit();
+        var level = loki.LogLevel.info;
+        if (obj_or_err) |obj| {
+            iperf3_log.info("successfully parsed json {d}", .{timestamp});
+            if (obj.@"error") |err| {
+                iperf3_log.err("error from iperf3: {s}", .{err});
+                level = loki.LogLevel.@"error";
+            }
+        } else |err| switch (err) {
+            error.UnknownField => iperf3_log.err("unknown field parsing json {d}", .{timestamp}),
+            error.UnexpectedEndOfInput => iperf3_log.err("unexpected end of input parsing json {d}", .{timestamp}),
+            else => iperf3_log.err("other error while parsing json {} {d}", .{ err, timestamp }),
+        }
+
+        // var line = std.ArrayList(u8).init(allocator);
+        // try std.json.stringify(
+        //     obj.value,
+        //     .{
+        //         .emit_null_optional_fields = false,
+        //     },
+        //     line.writer(),
+        // );
+        // defer line.deinit();
 
         const streams = loki.LokiStreams{
             .streams = &[_]loki.LokiStream{
@@ -200,12 +231,12 @@ pub fn main() !void {
                     .stream = .{
                         .job = "iperf3",
                         .server = hostname,
-                        .level = if (obj.value.@"error" == null) .info else .@"error",
+                        .level = level,
                     },
                     .values = &[_]loki.LokiValue{
                         .{
-                            .ts = std.time.nanoTimestamp(),
-                            .line = line.items,
+                            .ts = timestamp,
+                            .line = stdout.items,
                         },
                     },
                 },
@@ -238,13 +269,31 @@ pub fn main() !void {
         var req = try client.request(.POST, uri, headers, .{});
         defer req.deinit();
 
+        iperf3_log.info("sending stream to loki", .{});
+
         try req.start();
         try req.writeAll(data.items);
         try req.finish();
         try req.wait();
 
-        iperf3_log.info("{}\n", .{req.response.status});
+        if (req.response.status == .no_content) {
+            iperf3_log.info("successfully sent stream to loki", .{});
+        } else {
+            iperf3_log.info("response from loki: {}\n", .{req.response.status});
+        }
+        const term = try c.wait();
 
-        _ = try c.wait();
+        switch (term) {
+            .Exited => |value| {
+                if (value == 0) {
+                    iperf3_log.info("iperf3 competed successfully", .{});
+                } else {
+                    iperf3_log.info("iperf3 exited with error {d}", .{value});
+                }
+            },
+            else => {
+                iperf3_log.info("iperf3 terminated: {}", .{term});
+            },
+        }
     }
 }