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 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 MAX_ARGS uint32 = 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 MAX_ARG_NAME_LENGTH uint32 = 256;

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

/// Type alias for logging severity.
alias RawSeverity = uint8;

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

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

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