Mojo Log service and a thread-safe client library.

mojo/services/log/interfaces/entry.mojom

+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+module mojo.log;
+
+// Log levels: Levels less than |kLogLevelVerbose| are valid and indicate
+// greater levels of verbosity. Levels greater than |kLogLevelFatal| are
+// invalid and should be taken to be equivalent to |kLogLevelFatal|.

[viettrungluu, 2015/11/20 23:21:51]

Then they're not invalid, are they?

Just say that they're equivalent to |kLogLevelFatal|.

[vardhan, 2015/12/02 00:06:13]

Done.

+

[viettrungluu, 2015/11/20 23:21:51]

nit: no blank line here

[vardhan, 2015/12/02 00:06:13]

Done.

+const int32 kLogLevelVerbose = -1;
+const int32 kLogLevelInfo = 0;
+const int32 kLogLevelWarning = 1;
+const int32 kLogLevelError = 2;
+const int32 kLogLevelFatal = 3;
+
+// Describes a log message and its origin in source code. It is used by the

[viettrungluu, 2015/11/20 23:21:51]

The origin in source code is entirely incidental; that's just one type of
metadata. (We may add more metadata as desired.)

Note that source_file is optional.

[vardhan, 2015/12/02 00:06:13]

I'll remove this bit then.

+// |mojo::log::Log| service (see log.mojom).
+struct Entry {
+  // Client-side timestamp.
+  int64 timestamp;
+  // Log level: one of |kLogLevel...|.

[viettrungluu, 2015/11/20 23:21:51]

Not necessarily, as indicated by the comment above |kLogLevel...|.

[vardhan, 2015/12/02 00:06:13]

Done.

+  int32 log_level;
+
+  // The client source location this log originated from.
+  string? source_file;
+  uint32 source_line = 0;

[viettrungluu, 2015/11/20 23:21:51]

Should comment that:
- This is a 1-based line number.
- 0 means invalid/ignored.
- The line number will be ignored if source_file is not present.

[vardhan, 2015/12/02 00:06:13]

Done.

+
+  string? message;

[viettrungluu, 2015/11/20 23:21:51]

|message| should come before source_file and source_line, being a more basic
thing.

(We'll nearly always want a messsage, even if source_file/source_line aren't
present or aren't applicable.)

[vardhan, 2015/12/02 00:06:13]

Done.

+};