sdk/fidl/fuchsia.developer.ffx/tracing.fidl

// Copyright 2021 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.developer.ffx;

using fuchsia.tracing.controller;

/// This covers erorr from using the `Tracing` protocol below (specifically
/// trace recording errors).
type RecordingError = strict enum {
    /// Error encountered when opening the proxy to the target.
    TARGET_PROXY_OPEN = 0;

    /// This is a general error when starting a trace.
    RECORDING_START = 1;

    /// An error encountered if a trace recording has already been started
    /// for a given Fuchsia target.
    RECORDING_ALREADY_STARTED = 2;

    /// An error encountered when attempting to stop a trace. This causes an
    /// immediate termination of the client channel, so the user should not
    /// attempt to run `StopRecording` again.
    RECORDING_STOP = 3;

    /// Error for when a trace file is already being written to by the tracing
    /// service.
    DUPLICATE_TRACE_FILE = 4;

    /// When attempting to stop a trace, there were no active traces found for
    /// the given lookup name.
    NO_SUCH_TRACE_FILE = 5;

    /// No targets were found matching the query.
    NO_SUCH_TARGET = 6;

    /// The query matched a target that is not connected to the Daemon's FIDL
    /// channels.
    DISCONNECTED_TARGET = 7;
};

/// An action to be preformed on this trace. Used as part of a Trigger.
type Action = strict enum {
    /// Terminates the active trace.
    TERMINATE = 1;
};

/// A trigger is an action that is done when a certain alert has been raised in the
/// fuchsia tracing system.
type Trigger = table {
    /// The name of the alert being watched.
    /// See fuchsia.tracing.controller.Controller.WatchAlert for more info.
    1: alert string:fuchsia.tracing.controller.MAX_ALERT_NAME_LENGTH;

    /// The action to run when this alert has been witnessed.
    2: action Action;
};

/// Covers how a trace will be run when invoking `StartRecording`.
type TraceOptions = table {
    /// Determines how long a trace recording will run before terminating in
    /// fractional seconds. This is an "at-least" duration, with the actual
    /// runtime terminating likely a few dozen milliseconds longer.
    ///
    /// If this is not set, a trace will run indefinitely and must be stopped
    /// using `StopRecording`. Or by cleanly shutting down the daemon via
    /// `ffx daemon stop` or by using the Deamon proxy itself.
    1: duration float64;

    /// The triggers to run against this trace.
    2: triggers vector<Trigger>:MAX;
};

@discoverable
protocol Tracing {
    /// Starts a trace recording. If the target behind the query is already
    /// running a trace, or some trace is actively writing to the output file,
    /// this will return a [RecordingAlreadyStarted] error.
    ///
    /// On success, returns the target on which the trace is running.
    StartRecording(struct {
        target_query TargetQuery;
        output_file string:255;
        options TraceOptions;
        target_config fuchsia.tracing.controller.TraceConfig;
    }) -> (struct {
        target TargetInfo;
    }) error RecordingError;

    /// Stops the trace recording, flushing the remaining contents to the output
    /// file.
    ///
    /// Parameters:
    /// - name: A string that is first used to look up a target under which the
    ///         trace is running. It is used the same way as
    ///         `TargetQuery.string_matcher`. If no target can be found
    ///         associated with a trace, this will fall back to being
    ///         interpreted as a file name.
    ///
    /// Returns:
    /// - the resolved target for which the trace was running.
    ///
    /// Examples:
    ///
    /// ```
    /// proxy.start_recording(
    ///     target_query: TargetQuery { string_matcher: "foo"},
    ///     output_file: "output_file.fxt",
    ///     ...
    /// );
    ///
    /// // Can be stopped via this invocation (preferred).
    /// proxy.stop_recording("foo");
    ///
    /// // Can also be stopped via this invocation.
    /// proxy.stop_recording("output_file.fxt");
    /// ```
    StopRecording(struct {
        name string:255;
    }) -> (struct {
        target TargetInfo;
    }) error RecordingError;

    /// Reports the current status of all running traces.
    Status(resource struct {
        iterator server_end:TracingStatusIterator;
    }) -> ();
};

type TraceInfo = table {
    /// The target on which the trace is running.
    1: target TargetInfo;

    /// Path to the output file.
    2: output_file string:255;

    /// The total duration of the command in fractional seconds. This will not
    /// be set if the command is supposed to run indefinitely.
    3: duration float64;

    /// The amount of time remaining before the trace terminates. This will not
    /// be set if the command is supposed to run indefinitely.
    4: remaining_runtime float64;

    /// The original config sent to the `StartRecording` command.
    5: config fuchsia.tracing.controller.TraceConfig;

    /// A list of triggers active for this trace. See [Trigger] for more info.
    6: triggers vector<Trigger>:MAX;
};

protocol TracingStatusIterator {
    /// Gets the next block of trace info entries.
    GetNext() -> (struct {
        entries vector<TraceInfo>:MAX;
    });
};