sdk/fidl/fuchsia.diagnostics.stream/record.fidl

// Copyright 2019 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

library fuchsia.diagnostics.stream;
using fuchsia.diagnostics;
using zx;

/// Maximum number of arguments that can be encoded per record, as specified by the tracing format:
///
/// https://fuchsia.dev/fuchsia-src/development/tracing/trace-format#arguments
const uint32 MAX_ARGS = 15;

/// A small(ish) limit on the length of argument names is used because argument names are expected
/// to be used repeatedly, many times.
const uint32 MAX_ARG_NAME_LENGTH = 256;

/// The maximum string length which we can encode into the tracing format.
const uint32 MAX_TEXT_ARG_LENGTH = 32768;

/// A record in the diagnostic stream.
[MaxHandles = "0"]
struct Record {
    /// The monotonic time at which the record was generated.
    zx.time timestamp;
    /// Severity of the record.
    fuchsia.diagnostics.Severity severity;
    /// The key-value pairs which make up this record.
    vector<Argument>:MAX_ARGS arguments;
};

/// A named key-value pair in the diagnostic record.
[MaxHandles = "0"]
struct Argument {
    /// The name of the argument.
    string:MAX_ARG_NAME_LENGTH name;
    /// The value of the argument.
    Value value;
};

/// An argument value which can be one of several types.
[MaxHandles = "0"]
flexible union Value {
    /// A signed integral argument.
    1: int64 signed_int;
    /// An unsigned integral argument.
    2: uint64 unsigned_int;
    /// A double-precision floating-point argument.
    3: float64 floating;
    /// A UTF8 text argument.
    4: string:MAX_TEXT_ARG_LENGTH text;
};