system/fidl/logger/logger.fidl

// Copyright 2018 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.logger;

enum LogLevelFilter: int8 {
  NONE = -1;
  INFO = 0;
  WARN = 1;
  ERROR = 2;
  FATAL = 3;
};

// Max tags that can be passed to filter by listener.
const uint8 kMaxTags = 5;

// Max tag length that can be passed to filter by listener.
const uint8 kMaxTagLen = 63;

struct LogFilterOptions {
  bool filter_by_pid;
  uint64 pid;

  bool filter_by_tid;
  uint64 tid;

  // If more than zero, logs would be filtered based on verbosity and
  // |min_severity| would be ignored.
  uint8 verbosity;

  LogLevelFilter min_severity;

  // If non-empty, return all messages which contain at least one specified tag.
  // If empty, messages will not be filtered by tag.
  // Passed tags should not be more than |kMaxTagLen| bytes in length and max
  // tags can be |kMaxTags|.
  // Listener would be discarded if the limit is not followed.
  vector<string>:kMaxTags tags;
};

struct LogMessage {
  uint64 pid;
  uint64 tid;
  // Nanoseconds since the system was powered on, aka ZX_CLOCK_MONOTONIC.
  // https://fuchsia.googlesource.com/zircon/+/master/docs/syscalls/clock_get.md#supported-clock-ids
  uint64 time;
  int32 severity;

  // See //zircon/system/ulib/syslog/include/syslog/wire_format.h. As messages
  // can be served out of order, this should only be logged if more than last
  // count.
  uint32 dropped_logs;
  vector<string>:5 tags;
  string msg;
};

// Interface for LogListener to listen to.
[Discoverable]
interface Log {
  // Listener listens for logs
  1: Listen(LogListener log_listener, LogFilterOptions? options);

  // Dump all cached logs and then call |Done| function of |LogListener|.
  2: DumpLogs(LogListener log_listener, LogFilterOptions? options);
};

// Interface to get and listen to socket from syslogger
[Discoverable]
interface LogSink {
  // Client connects to send logs over socket
  1: Connect(handle<socket> socket);
};

const uint64 kMaxLogManySize = 16384;

interface LogListener {
  // Called for single messages.
  1: Log(LogMessage log);

  // Called when |Log| service is serving cached logs.
  // Max logs size per call is |kMaxLogManySize| bytes.
  2: LogMany(vector<LogMessage> Log);

  // Would be only called if |DumpLogs| function of |Log| service is called.
  3: Done();
};